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- text: "the need for magnetic resonance imaging ( mri ) in patients with an implanted pacemaker or implantable cardioverter - defibrillator ( icd ) is a growing clinical issue . it is estimated that as many as 75% of active cardiac device recipients will become indicated for mri . currently , the vast majority of such devices are contraindicated for use with an mri . in european heart rhythm association survey , published recently for non - mri - certified icds ( 0.51.5 t field strength ) , the totally subcutaneous icd ( s - icd ) system , an implantable defibrillator with no leads that touch the heart , has recently been demonstrated to be a safe and effective defibrillator option for patients at risk for sudden cardiac death . it provides shock therapy and post - shock pacing therapy , but no long - term bradycardia pacing . although it has been shown as an alternative to the standard transvenous icd , its compatibility with mri remains unclear . various types of clinical mri systems currently use a superconductive magnet that creates a static magnetic field strength , typically 1.5 or 3 t. the use of mri with most pacemakers and icds is considered a contraindication due to potential hazards , including heating of the electrode that resides in or on the heart , damage to myocardium , elevation of pacing thresholds , unintended induction of ventricular tachycardia ( vt ) or ventricular fibrillation ( vf ) , pacing inhibition , permanent device malfunction , and distortion of the mri scan . recently , mr - conditional. mr - conditional indicates a lack of known hazards in a specified mri environment with specified conditions of use . due to the variety of mri scanners and scanning protocols , it is not practical to test even a single device under all conditions . hence , mr - conditional labelling dictates that the device is safe for use under certain scanning conditions , as well as how the cardiac device should be programmed before an exposure to the magnetic field in a mri scanner . the literature , although limited , provides some guidance for imaging patients with implanted pacemakers or icds that do not have mr - conditional labelling . this single - centre prospective non - controlled study describes the first use of mri in patients with an implanted s - icd . patients with implanted s - icd systems ( boston scientific sqrx model 1010 and q - trak model 3010 ) were enrolled for mri testing over a period of 18 months . the s - icd system implanted in this patient cohort was composed of a can implanted in a left mid - lateral pocket and a para - sternal subcutaneous electrode . the s - icd is currently not certified for use with an mri ; therefore , the ethics committee of homolka hospital , prague , czech republic approved our clinical study . patients with newly implanted s - icd systems ( < 6 weeks ) were excluded , and none of the patients had any intravascular leads . the patients were randomized for either a cardiac , brain , cervical , or lumbar spinal scan . one of the subjects underwent an additional knee examination , due to reported chronic pain . a total of 15 patients were enrolled into this study ( 12 males and three females , aged 2283 years , mean 53 years . subjects in our cohort ( table 1 ) underwent a total of 22 mri scans between 6 june 2012 and 24 december 2013 . in total , five brain scans , three cardiac scans , 12 lumbar scans , one knee , and one cervical spine scan were conducted ( table 2 ) . however , in one patient a minor disc protrusion was found , in other mri revealed stenosis of intervertebral foramen which was causing radicular pain of the nerve root l4 and based on this examination the patient was referred to ct - navigated periradicular therapy . table 1summary of patient anatomical data and scan locations , along with noted clinical eventsidagesexbmidgef , % indication for s - icdheating0164f20.5hcmp / vfs85secondary preventionnone0283m30.0post - mi / smvts post - catheter ablation/35secondary prevention ( post - transvenous icd extraction)none0331m25.3arvc / d / smvts68secondary preventionin - tolerable re - scanned0458m23.6post - mi / post - cabg30primary preventionnone0577m25.5post - mi30primary preventionnone0663m27.0post - mi30primary preventionnone0768m23.7post - mi / vfs / vts60secondary prevention post - transvenous icd extraction / svc occlusiontolerable0822m29.4brugada sy / vfs68secondary preventionin - tolerable re - scanned0959m27.1dcmp / vfs / post - mitral valve surgery/60secondary prev./post - transvenous icd extractionnone1041f24.6arvc / d70primary preventionnone1123f21.5lqts / vf60secondary preventionnone1266m36.9post - mi / vf / post - cabg50secondary prevention / post - repeat transvenous icd extractiontolerable1348m22.9dcmp(non - compaction)/vfs35secondary preventionnone1470m29systolic dysfunction of lv35primary preventionnone1526m33brugada sy65primary preventionnonehcmp , hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts , long qt syndrom . table 2parmeters of s - icd and patient sensation during individual mri scansscan # idbody partheating sensationsshock zone ( b.p.m.)condit . shock zone ( b.p.m.)bat % episode num.101brainnone2302101001202brainnone240220861303l spinein - tolerable240220831403brainnone240220831504brainnone220190691605l spinenone220210541706l spinenone240220681807l spinetolerable240220582908l spinein - tolerablenananana1008brainnonenananana1108l spinenone2302108411209heartnone2402208911310l spinenone2301807911410heartnonenananana1511heartnone2301909711612l spinetolerable2001709721712l spinenone2001709421813c spinenone23019010041913l spinenone23019010042014l spinenone2301908612115kneenone25021010012215l spinenone2502101001s - icd parameters acquired prior- and post - mri were without any change , therefore only one value is presented.indices : na , not available ; l spine , lumbar spine ; c spine , cervical spine . summary of patient anatomical data and scan locations , along with noted clinical events hcmp , hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts , long qt syndrom . parmeters of s - icd and patient sensation during individual mri scans s - icd parameters acquired prior- and post - mri were without any change , therefore only one value is presented . indices : na , not available ; l spine , lumbar spine ; c spine , cervical spine . studies were performed using a siemens avanto 1.5 t mri scanner ( vb17 software , quantum gradient coils ) . all scans were run in normal operating mode , which is limited to 2 w / kg whole body averaged specific absorption rate ( sar ) . clinically relevant mri sequences were used for evaluation ( see table 3 ) . table 3types of pulse sequences typically used for imaging of respective anatomical areasscan locationscan sequencesflairdwiflashfsehastesestirtruefispbrainxxxxheartxxxxcervical spinexxkneexxxxlumbar spinexxflair , fluid attenuated inversion recovery ; dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast spin echo ; haste , half acquisition single - shot turbo spin echo ; se , spin echo ; stir , short tau inversion recovery ; truefisp , true fast imaging with steady - state precession.fse sequence caused heating in subjects with a thermistor probe during lumbar spine examination ( see the text for details ) . types of pulse sequences typically used for imaging of respective anatomical areas flair , fluid attenuated inversion recovery ; dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast spin echo ; haste , half acquisition single - shot turbo spin echo ; se , spin echo ; stir , short tau inversion recovery ; truefisp , true fast imaging with steady - state precession . fse sequence caused heating in subjects with a thermistor probe during lumbar spine examination ( see the text for details ) . patients were asked to report immediately any pain , torqueing movement , or heating sensation in the area of the pocket or the electrode by pressing an emergency bulb . furthermore , all patients were questioned immediately following the mri procedure to ascertain any discomfort in the vicinity of the can or electrode . pulse oximetry and standard lead electrocardiogram ( ecg ) if discomfort occurred , the patient was asked if the scan could be repeated at a later time using a revised scan sequence or the subject was again randomized for another anatomical area . since none of the components of the s - icd system are on or in the heart , heating near or around however , heating near the electrode or can with the s - icd system may still cause serious patient discomfort . therefore , along with education of subjects , each patient was instrumented by taping an oesophageal temperature probe ( beta - therm model g22k7mcd8 ) on the skin over the mid - lateral implant site to record any temperature excursions that might be correlated to patient symptoms of heating / discomfort near the pocket . to minimize the risk of inappropriate therapy , the s - icd system was programmed to therapy each s - icd system was evaluated prior to and immediately after the scan to verify proper functioning , including interrogation , sensing , and battery voltage . after the completion of the mri , long - term regular clinical follow - up and checking of the device were performed . patients with implanted s - icd systems ( boston scientific sqrx model 1010 and q - trak model 3010 ) were enrolled for mri testing over a period of 18 months . the s - icd system implanted in this patient cohort was composed of a can implanted in a left mid - lateral pocket and a para - sternal subcutaneous electrode . the s - icd is currently not certified for use with an mri ; therefore , the ethics committee of homolka hospital , prague , czech republic approved our clinical study . patients with newly implanted s - icd systems ( < 6 weeks ) were excluded , and none of the patients had any intravascular leads . the patients were randomized for either a cardiac , brain , cervical , or lumbar spinal scan . one of the subjects underwent an additional knee examination , due to reported chronic pain . a total of 15 patients were enrolled into this study ( 12 males and three females , aged 2283 years , mean 53 years . subjects in our cohort ( table 1 ) underwent a total of 22 mri scans between 6 june 2012 and 24 december 2013 . in total , five brain scans , three cardiac scans , 12 lumbar scans , one knee , and one cervical spine scan were conducted ( table 2 ) . however , in one patient a minor disc protrusion was found , in other mri revealed stenosis of intervertebral foramen which was causing radicular pain of the nerve root l4 and based on this examination the patient was referred to ct - navigated periradicular therapy . table 1summary of patient anatomical data and scan locations , along with noted clinical eventsidagesexbmidgef , % indication for s - icdheating0164f20.5hcmp / vfs85secondary preventionnone0283m30.0post - mi / smvts post - catheter ablation/35secondary prevention ( post - transvenous icd extraction)none0331m25.3arvc / d / smvts68secondary preventionin - tolerable re - scanned0458m23.6post - mi / post - cabg30primary preventionnone0577m25.5post - mi30primary preventionnone0663m27.0post - mi30primary preventionnone0768m23.7post - mi / vfs / vts60secondary prevention post - transvenous icd extraction / svc occlusiontolerable0822m29.4brugada sy / vfs68secondary preventionin - tolerable re - scanned0959m27.1dcmp / vfs / post - mitral valve surgery/60secondary prev./post - transvenous icd extractionnone1041f24.6arvc / d70primary preventionnone1123f21.5lqts / vf60secondary preventionnone1266m36.9post - mi / vf / post - cabg50secondary prevention / post - repeat transvenous icd extractiontolerable1348m22.9dcmp(non - compaction)/vfs35secondary preventionnone1470m29systolic dysfunction of lv35primary preventionnone1526m33brugada sy65primary preventionnonehcmp , hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts , long qt syndrom . table 2parmeters of s - icd and patient sensation during individual mri scansscan # idbody partheating sensationsshock zone ( b.p.m.)condit . shock zone ( b.p.m.)bat % episode num.101brainnone2302101001202brainnone240220861303l spinein - tolerable240220831403brainnone240220831504brainnone220190691605l spinenone220210541706l spinenone240220681807l spinetolerable240220582908l spinein - tolerablenananana1008brainnonenananana1108l spinenone2302108411209heartnone2402208911310l spinenone2301807911410heartnonenananana1511heartnone2301909711612l spinetolerable2001709721712l spinenone2001709421813c spinenone23019010041913l spinenone23019010042014l spinenone2301908612115kneenone25021010012215l spinenone2502101001s - icd parameters acquired prior- and post - mri were without any change , therefore only one value is presented.indices : na , not available ; l spine , lumbar spine ; c spine , cervical spine . summary of patient anatomical data and scan locations , along with noted clinical events hcmp , hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts , long qt syndrom . parmeters of s - icd and patient sensation during individual mri scans s - icd parameters acquired prior- and post - mri were without any change , therefore only one value is presented . indices : na , not available ; l spine , lumbar spine ; c spine , cervical spine . studies were performed using a siemens avanto 1.5 t mri scanner ( vb17 software , quantum gradient coils ) . all scans were run in normal operating mode , which is limited to 2 w / kg whole body averaged specific absorption rate ( sar ) . clinically relevant mri sequences were used for evaluation ( see table 3 ) . table 3types of pulse sequences typically used for imaging of respective anatomical areasscan locationscan sequencesflairdwiflashfsehastesestirtruefispbrainxxxxheartxxxxcervical spinexxkneexxxxlumbar spinexxflair , fluid attenuated inversion recovery ; dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast spin echo ; haste , half acquisition single - shot turbo spin echo ; se , spin echo ; stir , short tau inversion recovery ; truefisp , true fast imaging with steady - state precession.fse sequence caused heating in subjects with a thermistor probe during lumbar spine examination ( see the text for details ) . types of pulse sequences typically used for imaging of respective anatomical areas flair , fluid attenuated inversion recovery ; dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast spin echo ; haste , half acquisition single - shot turbo spin echo ; se , spin echo ; stir , short tau inversion recovery ; truefisp , true fast imaging with steady - state precession . fse sequence caused heating in subjects with a thermistor probe during lumbar spine examination ( see the text for details ) . patients were asked to report immediately any pain , torqueing movement , or heating sensation in the area of the pocket or the electrode by pressing an emergency bulb . furthermore , all patients were questioned immediately following the mri procedure to ascertain any discomfort in the vicinity of the can or electrode . pulse oximetry and standard lead electrocardiogram ( ecg ) if discomfort occurred , the patient was asked if the scan could be repeated at a later time using a revised scan sequence or the subject was again randomized for another anatomical area . since none of the components of the s - icd system are on or in the heart , heating near or around the electrode can not harm the myocardium . however , heating near the electrode or can with the s - icd system may still cause serious patient discomfort . therefore , along with education of subjects , each patient was instrumented by taping an oesophageal temperature probe ( beta - therm model g22k7mcd8 ) on the skin over the mid - lateral implant site to record any temperature excursions that might be correlated to patient symptoms of heating / discomfort near the pocket . to minimize the risk of inappropriate therapy , the s - icd system was programmed to therapy each s - icd system was evaluated prior to and immediately after the scan to verify proper functioning , including interrogation , sensing , and battery voltage . after the completion of the mri , the s - icd system was reprogrammed to original settings . long - term regular clinical follow - up and checking of the device were performed . no anomalies were noted via pulse oximetry or ecg during the scans for any of the patients . eleven of 15 patients reported no sensation or pain from heating of the can , two of 15 patients reported feeling some heating , and two patients reported intolerable heating ( see table 2 ) . in patients with intolerable heating , the scan was halted within seconds and changed to a scan of the brain , which proceeded without incident . patient reports of heating in the vicinity of the can occurred only during lumbar scans with a thermistor probe ; no such reports occurred during scans of the brain , cardiac area , cervical spine , or without the probe . in two cases where heating in the vicinity of the can was reported by the patient , the scan sequence was altered to reduce the intensity of radiofrequency ( rf ) field exposure by reducing the turbo factor ( e.g. from 21 to 7 ) , increasing the repetition time ( e.g. to > 4000 ms ) , and reducing the flip angle ( e.g. from 170 to 120 ) . the target values were chosen arbitrarily to maintain image contrast ( flip angle ) and keep scan time at reasonable limits ( turbo factor and repetition time ) . less heating was noted by patients after these modifications to the scan parameters were made . 03 ) was observed to have a skin lesion , appearing to be a circular rash or ulcer on the surface of the skin over the can , approximately 35 mm in diameter . the cause of this skin anomaly is not known ; it was later noted to have fully healed at a follow - up 10 days after the scan . to ascertain the effect of heating due to the instrumented thermistor catheter , the two patients who experienced the heating ( examinations 9 and 16 , see table 2 ) were rescanned several weeks later without the thermistor catheter in place ( examinations 11 and 17 ) . first , modified sequence ( with even lower amount of energy deposited in the tissue ) was used , which caused no heating . as no sensation was reported by the subjects , they were asked to report even a minimal discomfort , and the lumbar scans were performed using the same settings that resulted in heating with the thermistor catheter in place in the first imaging session . the results of the rescans revealed that no heating was felt by the patients when the thermistor catheter was absent . there were no noted changes to battery voltage , ability to detect the qrs signal or stored diagnostic data . pacing thresholds can not be assessed by the s - icd system , so this was not evaluated . none of the patients reported any pulling or twisting of the can or pain from heating of the s - icd electrode . for scans of the brain , lumbar spine , knee , and cervical spine , no effect from image artefact was noted in the anatomical area of interest . however , for scans of the cardiac area , image artefact was noted to interfere with the ability to see parts of the left ventricle , though the right ventricle of the heart was unaffected and could be imaged usefully . this was due to the can and not the electrode ( see figure 1 ) , modifications to the protocol for the lumbar spine resulted in a lower signal - to - noise ratio ; however , the images remain in diagnostic quality ( see figure 2 ) . figure 1kinetic study in four - chamber view : the systolic ( a and c ) and diastolic ( b and d ) images of cine sequences , four - chamber view . the steady - state free precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp kinetic study , an inflow of dark blood from the left pulmonary veins was seen . it could be caused by s - icd but also by metallic ring in mitral annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better , but an artefact at the lateral wall is obvious . figure 2lumbar spine imaging with icd : low sar t2 fse sequence ( upper image ) compared with normal t2 fse in the same subject ( lower image , for the scanning parameters see the discussion section ) . kinetic study in four - chamber view : the systolic ( a and c ) and diastolic ( b and d ) images of cine sequences , four - chamber view . the steady - state free precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp kinetic study , an inflow of dark blood from the left pulmonary veins was seen . it could be caused by s - icd but also by metallic ring in mitral annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better , but an artefact at the lateral wall is obvious . lumbar spine imaging with icd : low sar t2 fse sequence ( upper image ) compared with normal t2 fse in the same subject ( lower image , for the scanning parameters see the discussion section ) . there were no noted changes to battery voltage , ability to detect the qrs signal or stored diagnostic data . pacing thresholds can not be assessed by the s - icd system , so this was not evaluated . none of the patients reported any pulling or twisting of the can or pain from heating of the s - icd electrode . for scans of the brain , lumbar spine , knee , and cervical spine , no effect from image artefact was noted in the anatomical area of interest . however , for scans of the cardiac area , image artefact was noted to interfere with the ability to see parts of the left ventricle , though the right ventricle of the heart was unaffected and could be imaged usefully . this was due to the can and not the electrode ( see figure 1 ) , modifications to the protocol for the lumbar spine resulted in a lower signal - to - noise ratio ; however , the images remain in diagnostic quality ( see figure 2 ) . figure 1kinetic study in four - chamber view : the systolic ( a and c ) and diastolic ( b and d ) images of cine sequences , four - chamber view . the steady - state free precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp kinetic study , an inflow of dark blood from the left pulmonary veins was seen . it could be caused by s - icd but also by metallic ring in mitral annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better , but an artefact at the lateral wall is obvious . figure 2lumbar spine imaging with icd : low sar t2 fse sequence ( upper image ) compared with normal t2 fse in the same subject ( lower image , for the scanning parameters see the discussion section ) . kinetic study in four - chamber view : the systolic ( a and c ) and diastolic ( b and d ) images of cine sequences , four - chamber view . the steady - state free precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp kinetic study , an inflow of dark blood from the left pulmonary veins was seen . it could be caused by s - icd but also by metallic ring in mitral annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better , but an artefact at the lateral wall is obvious . lumbar spine imaging with icd : low sar t2 fse sequence ( upper image ) compared with normal t2 fse in the same subject ( lower image , there are several reports in the current literature about mr - conditional pacemakers from several companies , but very limited reports about mr - conditional icds . biotronik announced in late 2011 release of their first mr - compatible icd device and defibrillator leads pro mri , but in the conditions of use excluded scanning of the torso and focused more on the extremities examination . in european heart rhythm association survey , 60% of centres did not implant any mri - certified icds , 34.3% implanted < 10 icd devices , and only 5.6% implanted 10 and more icds ; one - fifth of responders stated that mri - certified icds should be implanted in all patients but lack of reimbursement was indicated as a possible obstacle to implant more mri - certified pacemakers / icds by 47.1% of responding centres . none of the components of the s - icd system are on or in the heart . the s - icd depends less upon being in direct contact with the myocardium to function and instead uses far - field sensing and stimulation to provide the shock and post - shock pacing therapy . as a consequence , unlike transvenous systems heating near or around the electrode can not harm the myocardium , which could present with possible safety consequences such as an elevation in pacing thresholds or scarring of the myocardium , but it may still cause serious patient discomfort . because the s - icd is larger than modern transvenous icd 's , there may be more potential for the can to experience heating due to the magnetic gradient or rf field . we report results from what we believe is the first experience of mri scanning in patients with an implanted s - icd and in various anatomical areas . overall , mri was performed safely in all patients , which is in contrast to the current literature with mri imaging in patients with electrical - active devices which are not mri - conditional . in our study , the primary clinically significant event attributable to the mri scan was the occurrence of heating in the area of the pocket in the four patients that underwent lumbar scans . it was not known if this was due to the s - icd can itself or an artefact of the thermistor catheter used to measure skin temperature over the pocket . this required a revision of our protocol , which was to re - scan two of the patients who complained of heating . re - scanning of these patients without the thermistor probe resulted in no complaints of heating , so it is assumed that the thermistor catheter itself heated during the lumbar scans and caused the discomfort . as further evidence , all the heating complaints occurred during rf - intensive scan sequences ( namely fast spin echo ) with the temperature probe located axially near the centre of the bore , where rf fields are the highest . the thermistor catheter is constructed of insulated conductive cables connected to electrodes and should couple to the rf fields efficiently , causing heating at the electrodes and pain or damage on the surface of the skin where the probe was placed over the s - icd can . if the heating was due to the s - icd can itself , it would more likely occur during gradient - intensive scan sequences ( which can generate eddy currents on can surfaces and internal components ) and at locations in the bore where there are high gradient fields , such as near the bore edges . however , when the patient was scanned with gradient - intensive scan sequences ( e.g. flair dwi ) and with the s - icd system in high gradient field locations in the bore ( e.g. such as during a brain scan ) , patients did not detect any heating or discomfort . in addition , the subcutaneous lead , which was not instrumented with a thermistor catheter , never resulted in any heating sensation noted by the patient , even when exactly the same sequence that resulted in heating in the first session was used . the use of mri - compatible temperature monitors such as fibre optic temperature probes would have provided better confirmation of possible skin temperature elevation and would not have been affected by the rf fields . for cardiac imaging , the main problem to solve is metallic artefact , especially on the gradient - echo sequences . like in research performed by nazarian et al . , several scan protocols were used to see if any yielded different effects or reduced the qualitative extent of artefact . gradient mode was changed from normal to whisper , resulting in slower ramping of the field and therefore diminishing the changes of the magnetic field in time . artefacts when present were limited to blurring of the left ventricle during cardiac scans and most yielded clinically useful information . standard interrogation of the s - icd revealed no adverse effects upon the functioning of the system . while no adverse effects upon the post - scan s - icd device function were noted , not all possible scanning protocols were tested . it should be noted that , four of the s - icd 's were exposed to repeat mri scans without adverse effects to device function . in addition , because the s - icd does not provide long - term bradycardia pacing , it is assumed that pacemaker - dependent patients would not be implanted with this system . the inhibition of the pacemaker function during the scanning sequence and possible pacing threshold changes are a unique concern in patients implanted with transvenous icds . this study included only 15 patients and 22 scans done on the same 1.5 t mri scanner . thus , even these preliminary results should only be applied to 1.5 t mri scanners ( similarly as reported in the present literature for other implantable devices ) . device functionality was tested immediately after the scan but not for long - term effects . in addition , not all device functions were tested although the s - icd system does have a beeper / interrogation warning if battery levels or memory irregularities occur . however , patients were scheduled for regular check - up and no defect of the device was observed in following 725 months ( mean observation time 18 months ) . delayed enhancement mri for determining cardiac scarring was also not tested . also , there are other anatomical areas that were not evaluated , such as shoulder and knees . this study included only 15 patients and 22 scans done on the same 1.5 t mri scanner . thus , even these preliminary results should only be applied to 1.5 t mri scanners ( similarly as reported in the present literature for other implantable devices ) . device functionality was tested immediately after the scan but not for long - term effects . in addition , not all device functions were tested although the s - icd system does have a beeper / interrogation warning if battery levels or memory irregularities occur . however , patients were scheduled for regular check - up and no defect of the device was observed in following 725 months ( mean observation time 18 months ) . delayed enhancement mri for determining cardiac scarring was also not tested . also , there are other anatomical areas that were not evaluated , such as shoulder and knees . while more data are required to support a claim of mri - conditional , this study is the study to demonstrate the feasibility of exposing s - icd patients to mri using the scanning and monitor protocol described , with some precautionary measures including : ( i ) programming the device therapy off ; ( ii ) limiting the sar to 2.0 w / kg ; ( iii ) continuous monitoring of the patients pulse oximetry and ecg by qualified personnel and especially for any feelings of heating ; ( iv ) evaluate device function post scan ; ( v ) availability of full resuscitation facilities at the mri site . given the variables of different mri scanners , the decision to perform mri on patients with an implanted s - icd system should be balanced against the potential risks . in our study , the only heating was very likely introduced by not fully mri - compatible thermometer probe ; subjects rescanned without the probe did not report any abnormalities during the scan of any body area listed ( brain , cervical and lumbar spine , heart , and knee ) . this study was supported by iga mz r nt12094/2011 , research project charles university in prague , prvouk p34 and unce 204010/2012 . funding to pay the open access publication charges for this article was provided by iga mz r nt12094/2011 ."
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9 |
example_title: Summarization Example 1
|
10 |
---
|
11 |
|
@@ -99,4 +543,4 @@ It is crucial to use this model responsibly and ethically, adhering to content g
|
|
99 |
References
|
100 |
Hugging Face Model Hub
|
101 |
T5 Paper
|
102 |
-
Disclaimer: The model's performance may be influenced by the quality and representativeness of the data it was fine-tuned on. Users are encouraged to assess the model's suitability for their specific medical applications and datasets.
|
|
|
1 |
---
|
2 |
+
license: mit
|
3 |
language:
|
4 |
- en
|
5 |
pipeline_tag: summarization
|
|
|
6 |
widget:
|
7 |
+
- text: >-
|
8 |
+
the need for magnetic resonance imaging ( mri ) in patients with an
|
9 |
+
implanted pacemaker or implantable cardioverter - defibrillator ( icd ) is a
|
10 |
+
growing clinical issue . it is estimated that as many as 75% of active
|
11 |
+
cardiac device recipients will become indicated for mri . currently , the
|
12 |
+
vast majority of such devices are contraindicated for use with an mri . in
|
13 |
+
european heart rhythm association survey , published recently for non - mri
|
14 |
+
- certified icds ( 0.51.5 t field strength ) , the totally subcutaneous icd
|
15 |
+
( s - icd ) system , an implantable defibrillator with no leads that touch
|
16 |
+
the heart , has recently been demonstrated to be a safe and effective
|
17 |
+
defibrillator option for patients at risk for sudden cardiac death . it
|
18 |
+
provides shock therapy and post - shock pacing therapy , but no long - term
|
19 |
+
bradycardia pacing . although it has been shown as an alternative to the
|
20 |
+
standard transvenous icd , its compatibility with mri remains unclear .
|
21 |
+
various types of clinical mri systems currently use a superconductive magnet
|
22 |
+
that creates a static magnetic field strength , typically 1.5 or 3 t. the
|
23 |
+
use of mri with most pacemakers and icds is considered a contraindication
|
24 |
+
due to potential hazards , including heating of the electrode that resides
|
25 |
+
in or on the heart , damage to myocardium , elevation of pacing thresholds ,
|
26 |
+
unintended induction of ventricular tachycardia ( vt ) or ventricular
|
27 |
+
fibrillation ( vf ) , pacing inhibition , permanent device malfunction , and
|
28 |
+
distortion of the mri scan . recently , mr - conditional. mr - conditional
|
29 |
+
indicates a lack of known hazards in a specified mri environment with
|
30 |
+
specified conditions of use . due to the variety of mri scanners and
|
31 |
+
scanning protocols , it is not practical to test even a single device under
|
32 |
+
all conditions . hence , mr - conditional labelling dictates that the device
|
33 |
+
is safe for use under certain scanning conditions , as well as how the
|
34 |
+
cardiac device should be programmed before an exposure to the magnetic field
|
35 |
+
in a mri scanner . the literature , although limited , provides some
|
36 |
+
guidance for imaging patients with implanted pacemakers or icds that do not
|
37 |
+
have mr - conditional labelling . this single - centre prospective non -
|
38 |
+
controlled study describes the first use of mri in patients with an
|
39 |
+
implanted s - icd . patients with implanted s - icd systems ( boston
|
40 |
+
scientific sqrx model 1010 and q - trak model 3010 ) were enrolled for mri
|
41 |
+
testing over a period of 18 months . the s - icd system implanted in this
|
42 |
+
patient cohort was composed of a can implanted in a left mid - lateral
|
43 |
+
pocket and a para - sternal subcutaneous electrode . the s - icd is
|
44 |
+
currently not certified for use with an mri ; therefore , the ethics
|
45 |
+
committee of homolka hospital , prague , czech republic approved our
|
46 |
+
clinical study . patients with newly implanted s - icd systems ( < 6 weeks )
|
47 |
+
were excluded , and none of the patients had any intravascular leads . the
|
48 |
+
patients were randomized for either a cardiac , brain , cervical , or lumbar
|
49 |
+
spinal scan . one of the subjects underwent an additional knee examination ,
|
50 |
+
due to reported chronic pain . a total of 15 patients were enrolled into
|
51 |
+
this study ( 12 males and three females , aged 2283 years , mean 53 years .
|
52 |
+
subjects in our cohort ( table 1 ) underwent a total of 22 mri scans between
|
53 |
+
6 june 2012 and 24 december 2013 . in total , five brain scans , three
|
54 |
+
cardiac scans , 12 lumbar scans , one knee , and one cervical spine scan
|
55 |
+
were conducted ( table 2 ) . however , in one patient a minor disc
|
56 |
+
protrusion was found , in other mri revealed stenosis of intervertebral
|
57 |
+
foramen which was causing radicular pain of the nerve root l4 and based on
|
58 |
+
this examination the patient was referred to ct - navigated periradicular
|
59 |
+
therapy . table 1summary of patient anatomical data and scan locations ,
|
60 |
+
along with noted clinical eventsidagesexbmidgef , % indication for s -
|
61 |
+
icdheating0164f20.5hcmp / vfs85secondary preventionnone0283m30.0post - mi /
|
62 |
+
smvts post - catheter ablation/35secondary prevention ( post - transvenous
|
63 |
+
icd extraction)none0331m25.3arvc / d / smvts68secondary preventionin -
|
64 |
+
tolerable re - scanned0458m23.6post - mi / post - cabg30primary
|
65 |
+
preventionnone0577m25.5post - mi30primary preventionnone0663m27.0post -
|
66 |
+
mi30primary preventionnone0768m23.7post - mi / vfs / vts60secondary
|
67 |
+
prevention post - transvenous icd extraction / svc
|
68 |
+
occlusiontolerable0822m29.4brugada sy / vfs68secondary preventionin -
|
69 |
+
tolerable re - scanned0959m27.1dcmp / vfs / post - mitral valve
|
70 |
+
surgery/60secondary prev./post - transvenous icd extractionnone1041f24.6arvc
|
71 |
+
/ d70primary preventionnone1123f21.5lqts / vf60secondary
|
72 |
+
preventionnone1266m36.9post - mi / vf / post - cabg50secondary prevention /
|
73 |
+
post - repeat transvenous icd extractiontolerable1348m22.9dcmp(non -
|
74 |
+
compaction)/vfs35secondary preventionnone1470m29systolic dysfunction of
|
75 |
+
lv35primary preventionnone1526m33brugada sy65primary preventionnonehcmp ,
|
76 |
+
hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular
|
77 |
+
tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right
|
78 |
+
ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts ,
|
79 |
+
long qt syndrom . table 2parmeters of s - icd and patient sensation during
|
80 |
+
individual mri scansscan # idbody partheating sensationsshock zone (
|
81 |
+
b.p.m.)condit . shock zone ( b.p.m.)bat % episode
|
82 |
+
num.101brainnone2302101001202brainnone240220861303l spinein -
|
83 |
+
tolerable240220831403brainnone240220831504brainnone220190691605l
|
84 |
+
spinenone220210541706l spinenone240220681807l spinetolerable240220582908l
|
85 |
+
spinein - tolerablenananana1008brainnonenananana1108l
|
86 |
+
spinenone2302108411209heartnone2402208911310l
|
87 |
+
spinenone2301807911410heartnonenananana1511heartnone2301909711612l
|
88 |
+
spinetolerable2001709721712l spinenone2001709421813c
|
89 |
+
spinenone23019010041913l spinenone23019010042014l
|
90 |
+
spinenone2301908612115kneenone25021010012215l spinenone2502101001s - icd
|
91 |
+
parameters acquired prior- and post - mri were without any change ,
|
92 |
+
therefore only one value is presented.indices : na , not available ; l spine
|
93 |
+
, lumbar spine ; c spine , cervical spine . summary of patient anatomical
|
94 |
+
data and scan locations , along with noted clinical events hcmp ,
|
95 |
+
hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular
|
96 |
+
tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right
|
97 |
+
ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts ,
|
98 |
+
long qt syndrom . parmeters of s - icd and patient sensation during
|
99 |
+
individual mri scans s - icd parameters acquired prior- and post - mri were
|
100 |
+
without any change , therefore only one value is presented . indices : na ,
|
101 |
+
not available ; l spine , lumbar spine ; c spine , cervical spine . studies
|
102 |
+
were performed using a siemens avanto 1.5 t mri scanner ( vb17 software ,
|
103 |
+
quantum gradient coils ) . all scans were run in normal operating mode ,
|
104 |
+
which is limited to 2 w / kg whole body averaged specific absorption rate (
|
105 |
+
sar ) . clinically relevant mri sequences were used for evaluation ( see
|
106 |
+
table 3 ) . table 3types of pulse sequences typically used for imaging of
|
107 |
+
respective anatomical areasscan locationscan
|
108 |
+
sequencesflairdwiflashfsehastesestirtruefispbrainxxxxheartxxxxcervical
|
109 |
+
spinexxkneexxxxlumbar spinexxflair , fluid attenuated inversion recovery ;
|
110 |
+
dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast
|
111 |
+
spin echo ; haste , half acquisition single - shot turbo spin echo ; se ,
|
112 |
+
spin echo ; stir , short tau inversion recovery ; truefisp , true fast
|
113 |
+
imaging with steady - state precession.fse sequence caused heating in
|
114 |
+
subjects with a thermistor probe during lumbar spine examination ( see the
|
115 |
+
text for details ) . types of pulse sequences typically used for imaging of
|
116 |
+
respective anatomical areas flair , fluid attenuated inversion recovery ;
|
117 |
+
dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast
|
118 |
+
spin echo ; haste , half acquisition single - shot turbo spin echo ; se ,
|
119 |
+
spin echo ; stir , short tau inversion recovery ; truefisp , true fast
|
120 |
+
imaging with steady - state precession . fse sequence caused heating in
|
121 |
+
subjects with a thermistor probe during lumbar spine examination ( see the
|
122 |
+
text for details ) . patients were asked to report immediately any pain ,
|
123 |
+
torqueing movement , or heating sensation in the area of the pocket or the
|
124 |
+
electrode by pressing an emergency bulb . furthermore , all patients were
|
125 |
+
questioned immediately following the mri procedure to ascertain any
|
126 |
+
discomfort in the vicinity of the can or electrode . pulse oximetry and
|
127 |
+
standard lead electrocardiogram ( ecg ) if discomfort occurred , the patient
|
128 |
+
was asked if the scan could be repeated at a later time using a revised scan
|
129 |
+
sequence or the subject was again randomized for another anatomical area .
|
130 |
+
since none of the components of the s - icd system are on or in the heart ,
|
131 |
+
heating near or around however , heating near the electrode or can with the
|
132 |
+
s - icd system may still cause serious patient discomfort . therefore ,
|
133 |
+
along with education of subjects , each patient was instrumented by taping
|
134 |
+
an oesophageal temperature probe ( beta - therm model g22k7mcd8 ) on the
|
135 |
+
skin over the mid - lateral implant site to record any temperature
|
136 |
+
excursions that might be correlated to patient symptoms of heating /
|
137 |
+
discomfort near the pocket . to minimize the risk of inappropriate therapy ,
|
138 |
+
the s - icd system was programmed to therapy each s - icd system was
|
139 |
+
evaluated prior to and immediately after the scan to verify proper
|
140 |
+
functioning , including interrogation , sensing , and battery voltage .
|
141 |
+
after the completion of the mri , long - term regular clinical follow - up
|
142 |
+
and checking of the device were performed . patients with implanted s - icd
|
143 |
+
systems ( boston scientific sqrx model 1010 and q - trak model 3010 ) were
|
144 |
+
enrolled for mri testing over a period of 18 months . the s - icd system
|
145 |
+
implanted in this patient cohort was composed of a can implanted in a left
|
146 |
+
mid - lateral pocket and a para - sternal subcutaneous electrode . the s -
|
147 |
+
icd is currently not certified for use with an mri ; therefore , the ethics
|
148 |
+
committee of homolka hospital , prague , czech republic approved our
|
149 |
+
clinical study . patients with newly implanted s - icd systems ( < 6 weeks )
|
150 |
+
were excluded , and none of the patients had any intravascular leads . the
|
151 |
+
patients were randomized for either a cardiac , brain , cervical , or lumbar
|
152 |
+
spinal scan . one of the subjects underwent an additional knee examination ,
|
153 |
+
due to reported chronic pain . a total of 15 patients were enrolled into
|
154 |
+
this study ( 12 males and three females , aged 2283 years , mean 53 years .
|
155 |
+
subjects in our cohort ( table 1 ) underwent a total of 22 mri scans between
|
156 |
+
6 june 2012 and 24 december 2013 . in total , five brain scans , three
|
157 |
+
cardiac scans , 12 lumbar scans , one knee , and one cervical spine scan
|
158 |
+
were conducted ( table 2 ) . however , in one patient a minor disc
|
159 |
+
protrusion was found , in other mri revealed stenosis of intervertebral
|
160 |
+
foramen which was causing radicular pain of the nerve root l4 and based on
|
161 |
+
this examination the patient was referred to ct - navigated periradicular
|
162 |
+
therapy . table 1summary of patient anatomical data and scan locations ,
|
163 |
+
along with noted clinical eventsidagesexbmidgef , % indication for s -
|
164 |
+
icdheating0164f20.5hcmp / vfs85secondary preventionnone0283m30.0post - mi /
|
165 |
+
smvts post - catheter ablation/35secondary prevention ( post - transvenous
|
166 |
+
icd extraction)none0331m25.3arvc / d / smvts68secondary preventionin -
|
167 |
+
tolerable re - scanned0458m23.6post - mi / post - cabg30primary
|
168 |
+
preventionnone0577m25.5post - mi30primary preventionnone0663m27.0post -
|
169 |
+
mi30primary preventionnone0768m23.7post - mi / vfs / vts60secondary
|
170 |
+
prevention post - transvenous icd extraction / svc
|
171 |
+
occlusiontolerable0822m29.4brugada sy / vfs68secondary preventionin -
|
172 |
+
tolerable re - scanned0959m27.1dcmp / vfs / post - mitral valve
|
173 |
+
surgery/60secondary prev./post - transvenous icd extractionnone1041f24.6arvc
|
174 |
+
/ d70primary preventionnone1123f21.5lqts / vf60secondary
|
175 |
+
preventionnone1266m36.9post - mi / vf / post - cabg50secondary prevention /
|
176 |
+
post - repeat transvenous icd extractiontolerable1348m22.9dcmp(non -
|
177 |
+
compaction)/vfs35secondary preventionnone1470m29systolic dysfunction of
|
178 |
+
lv35primary preventionnone1526m33brugada sy65primary preventionnonehcmp ,
|
179 |
+
hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular
|
180 |
+
tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right
|
181 |
+
ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts ,
|
182 |
+
long qt syndrom . table 2parmeters of s - icd and patient sensation during
|
183 |
+
individual mri scansscan # idbody partheating sensationsshock zone (
|
184 |
+
b.p.m.)condit . shock zone ( b.p.m.)bat % episode
|
185 |
+
num.101brainnone2302101001202brainnone240220861303l spinein -
|
186 |
+
tolerable240220831403brainnone240220831504brainnone220190691605l
|
187 |
+
spinenone220210541706l spinenone240220681807l spinetolerable240220582908l
|
188 |
+
spinein - tolerablenananana1008brainnonenananana1108l
|
189 |
+
spinenone2302108411209heartnone2402208911310l
|
190 |
+
spinenone2301807911410heartnonenananana1511heartnone2301909711612l
|
191 |
+
spinetolerable2001709721712l spinenone2001709421813c
|
192 |
+
spinenone23019010041913l spinenone23019010042014l
|
193 |
+
spinenone2301908612115kneenone25021010012215l spinenone2502101001s - icd
|
194 |
+
parameters acquired prior- and post - mri were without any change ,
|
195 |
+
therefore only one value is presented.indices : na , not available ; l spine
|
196 |
+
, lumbar spine ; c spine , cervical spine . summary of patient anatomical
|
197 |
+
data and scan locations , along with noted clinical events hcmp ,
|
198 |
+
hypertrophic cardiomyopathy ; smvt , sustained monomorphic ventricular
|
199 |
+
tachycardia ; mi , myocardial infarction ; arvc , arrhythmogenic right
|
200 |
+
ventricular cardiomyopathy ; cabg , coronary artery by - pass graft ; lqts ,
|
201 |
+
long qt syndrom . parmeters of s - icd and patient sensation during
|
202 |
+
individual mri scans s - icd parameters acquired prior- and post - mri were
|
203 |
+
without any change , therefore only one value is presented . indices : na ,
|
204 |
+
not available ; l spine , lumbar spine ; c spine , cervical spine . studies
|
205 |
+
were performed using a siemens avanto 1.5 t mri scanner ( vb17 software ,
|
206 |
+
quantum gradient coils ) . all scans were run in normal operating mode ,
|
207 |
+
which is limited to 2 w / kg whole body averaged specific absorption rate (
|
208 |
+
sar ) . clinically relevant mri sequences were used for evaluation ( see
|
209 |
+
table 3 ) . table 3types of pulse sequences typically used for imaging of
|
210 |
+
respective anatomical areasscan locationscan
|
211 |
+
sequencesflairdwiflashfsehastesestirtruefispbrainxxxxheartxxxxcervical
|
212 |
+
spinexxkneexxxxlumbar spinexxflair , fluid attenuated inversion recovery ;
|
213 |
+
dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast
|
214 |
+
spin echo ; haste , half acquisition single - shot turbo spin echo ; se ,
|
215 |
+
spin echo ; stir , short tau inversion recovery ; truefisp , true fast
|
216 |
+
imaging with steady - state precession.fse sequence caused heating in
|
217 |
+
subjects with a thermistor probe during lumbar spine examination ( see the
|
218 |
+
text for details ) . types of pulse sequences typically used for imaging of
|
219 |
+
respective anatomical areas flair , fluid attenuated inversion recovery ;
|
220 |
+
dwi , diffusion weighted imaging ; flash , fast low angle shot ; fse , fast
|
221 |
+
spin echo ; haste , half acquisition single - shot turbo spin echo ; se ,
|
222 |
+
spin echo ; stir , short tau inversion recovery ; truefisp , true fast
|
223 |
+
imaging with steady - state precession . fse sequence caused heating in
|
224 |
+
subjects with a thermistor probe during lumbar spine examination ( see the
|
225 |
+
text for details ) . patients were asked to report immediately any pain ,
|
226 |
+
torqueing movement , or heating sensation in the area of the pocket or the
|
227 |
+
electrode by pressing an emergency bulb . furthermore , all patients were
|
228 |
+
questioned immediately following the mri procedure to ascertain any
|
229 |
+
discomfort in the vicinity of the can or electrode . pulse oximetry and
|
230 |
+
standard lead electrocardiogram ( ecg ) if discomfort occurred , the patient
|
231 |
+
was asked if the scan could be repeated at a later time using a revised scan
|
232 |
+
sequence or the subject was again randomized for another anatomical area .
|
233 |
+
since none of the components of the s - icd system are on or in the heart ,
|
234 |
+
heating near or around the electrode can not harm the myocardium . however ,
|
235 |
+
heating near the electrode or can with the s - icd system may still cause
|
236 |
+
serious patient discomfort . therefore , along with education of subjects ,
|
237 |
+
each patient was instrumented by taping an oesophageal temperature probe (
|
238 |
+
beta - therm model g22k7mcd8 ) on the skin over the mid - lateral implant
|
239 |
+
site to record any temperature excursions that might be correlated to
|
240 |
+
patient symptoms of heating / discomfort near the pocket . to minimize the
|
241 |
+
risk of inappropriate therapy , the s - icd system was programmed to therapy
|
242 |
+
each s - icd system was evaluated prior to and immediately after the scan to
|
243 |
+
verify proper functioning , including interrogation , sensing , and battery
|
244 |
+
voltage . after the completion of the mri , the s - icd system was
|
245 |
+
reprogrammed to original settings . long - term regular clinical follow - up
|
246 |
+
and checking of the device were performed . no anomalies were noted via
|
247 |
+
pulse oximetry or ecg during the scans for any of the patients . eleven of
|
248 |
+
15 patients reported no sensation or pain from heating of the can , two of
|
249 |
+
15 patients reported feeling some heating , and two patients reported
|
250 |
+
intolerable heating ( see table 2 ) . in patients with intolerable heating ,
|
251 |
+
the scan was halted within seconds and changed to a scan of the brain ,
|
252 |
+
which proceeded without incident . patient reports of heating in the
|
253 |
+
vicinity of the can occurred only during lumbar scans with a thermistor
|
254 |
+
probe ; no such reports occurred during scans of the brain , cardiac area ,
|
255 |
+
cervical spine , or without the probe . in two cases where heating in the
|
256 |
+
vicinity of the can was reported by the patient , the scan sequence was
|
257 |
+
altered to reduce the intensity of radiofrequency ( rf ) field exposure by
|
258 |
+
reducing the turbo factor ( e.g. from 21 to 7 ) , increasing the repetition
|
259 |
+
time ( e.g. to > 4000 ms ) , and reducing the flip angle ( e.g. from 170 to
|
260 |
+
120 ) . the target values were chosen arbitrarily to maintain image contrast
|
261 |
+
( flip angle ) and keep scan time at reasonable limits ( turbo factor and
|
262 |
+
repetition time ) . less heating was noted by patients after these
|
263 |
+
modifications to the scan parameters were made . 03 ) was observed to have a
|
264 |
+
skin lesion , appearing to be a circular rash or ulcer on the surface of the
|
265 |
+
skin over the can , approximately 35 mm in diameter . the cause of this skin
|
266 |
+
anomaly is not known ; it was later noted to have fully healed at a follow -
|
267 |
+
up 10 days after the scan . to ascertain the effect of heating due to the
|
268 |
+
instrumented thermistor catheter , the two patients who experienced the
|
269 |
+
heating ( examinations 9 and 16 , see table 2 ) were rescanned several weeks
|
270 |
+
later without the thermistor catheter in place ( examinations 11 and 17 ) .
|
271 |
+
first , modified sequence ( with even lower amount of energy deposited in
|
272 |
+
the tissue ) was used , which caused no heating . as no sensation was
|
273 |
+
reported by the subjects , they were asked to report even a minimal
|
274 |
+
discomfort , and the lumbar scans were performed using the same settings
|
275 |
+
that resulted in heating with the thermistor catheter in place in the first
|
276 |
+
imaging session . the results of the rescans revealed that no heating was
|
277 |
+
felt by the patients when the thermistor catheter was absent . there were no
|
278 |
+
noted changes to battery voltage , ability to detect the qrs signal or
|
279 |
+
stored diagnostic data . pacing thresholds can not be assessed by the s -
|
280 |
+
icd system , so this was not evaluated . none of the patients reported any
|
281 |
+
pulling or twisting of the can or pain from heating of the s - icd electrode
|
282 |
+
. for scans of the brain , lumbar spine , knee , and cervical spine , no
|
283 |
+
effect from image artefact was noted in the anatomical area of interest .
|
284 |
+
however , for scans of the cardiac area , image artefact was noted to
|
285 |
+
interfere with the ability to see parts of the left ventricle , though the
|
286 |
+
right ventricle of the heart was unaffected and could be imaged usefully .
|
287 |
+
this was due to the can and not the electrode ( see figure 1 ) ,
|
288 |
+
modifications to the protocol for the lumbar spine resulted in a lower
|
289 |
+
signal - to - noise ratio ; however , the images remain in diagnostic
|
290 |
+
quality ( see figure 2 ) . figure 1kinetic study in four - chamber view :
|
291 |
+
the systolic ( a and c ) and diastolic ( b and d ) images of cine sequences
|
292 |
+
, four - chamber view . the steady - state free precession ( ssfp ) sequence
|
293 |
+
( a and b ) shows more artefacts . in ssfp kinetic study , an inflow of dark
|
294 |
+
blood from the left pulmonary veins was seen . it could be caused by s - icd
|
295 |
+
but also by metallic ring in mitral annulus . the spoiled gradient echo (
|
296 |
+
gre ) sequence ( c and d ) is better , but an artefact at the lateral wall
|
297 |
+
is obvious . figure 2lumbar spine imaging with icd : low sar t2 fse sequence
|
298 |
+
( upper image ) compared with normal t2 fse in the same subject ( lower
|
299 |
+
image , for the scanning parameters see the discussion section ) . kinetic
|
300 |
+
study in four - chamber view : the systolic ( a and c ) and diastolic ( b
|
301 |
+
and d ) images of cine sequences , four - chamber view . the steady - state
|
302 |
+
free precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp
|
303 |
+
kinetic study , an inflow of dark blood from the left pulmonary veins was
|
304 |
+
seen . it could be caused by s - icd but also by metallic ring in mitral
|
305 |
+
annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better ,
|
306 |
+
but an artefact at the lateral wall is obvious . lumbar spine imaging with
|
307 |
+
icd : low sar t2 fse sequence ( upper image ) compared with normal t2 fse in
|
308 |
+
the same subject ( lower image , for the scanning parameters see the
|
309 |
+
discussion section ) . there were no noted changes to battery voltage ,
|
310 |
+
ability to detect the qrs signal or stored diagnostic data . pacing
|
311 |
+
thresholds can not be assessed by the s - icd system , so this was not
|
312 |
+
evaluated . none of the patients reported any pulling or twisting of the can
|
313 |
+
or pain from heating of the s - icd electrode . for scans of the brain ,
|
314 |
+
lumbar spine , knee , and cervical spine , no effect from image artefact was
|
315 |
+
noted in the anatomical area of interest . however , for scans of the
|
316 |
+
cardiac area , image artefact was noted to interfere with the ability to see
|
317 |
+
parts of the left ventricle , though the right ventricle of the heart was
|
318 |
+
unaffected and could be imaged usefully . this was due to the can and not
|
319 |
+
the electrode ( see figure 1 ) , modifications to the protocol for the
|
320 |
+
lumbar spine resulted in a lower signal - to - noise ratio ; however , the
|
321 |
+
images remain in diagnostic quality ( see figure 2 ) . figure 1kinetic study
|
322 |
+
in four - chamber view : the systolic ( a and c ) and diastolic ( b and d )
|
323 |
+
images of cine sequences , four - chamber view . the steady - state free
|
324 |
+
precession ( ssfp ) sequence ( a and b ) shows more artefacts . in ssfp
|
325 |
+
kinetic study , an inflow of dark blood from the left pulmonary veins was
|
326 |
+
seen . it could be caused by s - icd but also by metallic ring in mitral
|
327 |
+
annulus . the spoiled gradient echo ( gre ) sequence ( c and d ) is better ,
|
328 |
+
but an artefact at the lateral wall is obvious . figure 2lumbar spine
|
329 |
+
imaging with icd : low sar t2 fse sequence ( upper image ) compared with
|
330 |
+
normal t2 fse in the same subject ( lower image , for the scanning
|
331 |
+
parameters see the discussion section ) . kinetic study in four - chamber
|
332 |
+
view : the systolic ( a and c ) and diastolic ( b and d ) images of cine
|
333 |
+
sequences , four - chamber view . the steady - state free precession ( ssfp
|
334 |
+
) sequence ( a and b ) shows more artefacts . in ssfp kinetic study , an
|
335 |
+
inflow of dark blood from the left pulmonary veins was seen . it could be
|
336 |
+
caused by s - icd but also by metallic ring in mitral annulus . the spoiled
|
337 |
+
gradient echo ( gre ) sequence ( c and d ) is better , but an artefact at
|
338 |
+
the lateral wall is obvious . lumbar spine imaging with icd : low sar t2 fse
|
339 |
+
sequence ( upper image ) compared with normal t2 fse in the same subject (
|
340 |
+
lower image , there are several reports in the current literature about mr -
|
341 |
+
conditional pacemakers from several companies , but very limited reports
|
342 |
+
about mr - conditional icds . biotronik announced in late 2011 release of
|
343 |
+
their first mr - compatible icd device and defibrillator leads pro mri , but
|
344 |
+
in the conditions of use excluded scanning of the torso and focused more on
|
345 |
+
the extremities examination . in european heart rhythm association survey ,
|
346 |
+
60% of centres did not implant any mri - certified icds , 34.3% implanted <
|
347 |
+
10 icd devices , and only 5.6% implanted 10 and more icds ; one - fifth of
|
348 |
+
responders stated that mri - certified icds should be implanted in all
|
349 |
+
patients but lack of reimbursement was indicated as a possible obstacle to
|
350 |
+
implant more mri - certified pacemakers / icds by 47.1% of responding
|
351 |
+
centres . none of the components of the s - icd system are on or in the
|
352 |
+
heart . the s - icd depends less upon being in direct contact with the
|
353 |
+
myocardium to function and instead uses far - field sensing and stimulation
|
354 |
+
to provide the shock and post - shock pacing therapy . as a consequence ,
|
355 |
+
unlike transvenous systems heating near or around the electrode can not harm
|
356 |
+
the myocardium , which could present with possible safety consequences such
|
357 |
+
as an elevation in pacing thresholds or scarring of the myocardium , but it
|
358 |
+
may still cause serious patient discomfort . because the s - icd is larger
|
359 |
+
than modern transvenous icd 's , there may be more potential for the can to
|
360 |
+
experience heating due to the magnetic gradient or rf field . we report
|
361 |
+
results from what we believe is the first experience of mri scanning in
|
362 |
+
patients with an implanted s - icd and in various anatomical areas . overall
|
363 |
+
, mri was performed safely in all patients , which is in contrast to the
|
364 |
+
current literature with mri imaging in patients with electrical - active
|
365 |
+
devices which are not mri - conditional . in our study , the primary
|
366 |
+
clinically significant event attributable to the mri scan was the occurrence
|
367 |
+
of heating in the area of the pocket in the four patients that underwent
|
368 |
+
lumbar scans . it was not known if this was due to the s - icd can itself or
|
369 |
+
an artefact of the thermistor catheter used to measure skin temperature over
|
370 |
+
the pocket . this required a revision of our protocol , which was to re -
|
371 |
+
scan two of the patients who complained of heating . re - scanning of these
|
372 |
+
patients without the thermistor probe resulted in no complaints of heating ,
|
373 |
+
so it is assumed that the thermistor catheter itself heated during the
|
374 |
+
lumbar scans and caused the discomfort . as further evidence , all the
|
375 |
+
heating complaints occurred during rf - intensive scan sequences ( namely
|
376 |
+
fast spin echo ) with the temperature probe located axially near the centre
|
377 |
+
of the bore , where rf fields are the highest . the thermistor catheter is
|
378 |
+
constructed of insulated conductive cables connected to electrodes and
|
379 |
+
should couple to the rf fields efficiently , causing heating at the
|
380 |
+
electrodes and pain or damage on the surface of the skin where the probe was
|
381 |
+
placed over the s - icd can . if the heating was due to the s - icd can
|
382 |
+
itself , it would more likely occur during gradient - intensive scan
|
383 |
+
sequences ( which can generate eddy currents on can surfaces and internal
|
384 |
+
components ) and at locations in the bore where there are high gradient
|
385 |
+
fields , such as near the bore edges . however , when the patient was
|
386 |
+
scanned with gradient - intensive scan sequences ( e.g. flair dwi ) and with
|
387 |
+
the s - icd system in high gradient field locations in the bore ( e.g. such
|
388 |
+
as during a brain scan ) , patients did not detect any heating or discomfort
|
389 |
+
. in addition , the subcutaneous lead , which was not instrumented with a
|
390 |
+
thermistor catheter , never resulted in any heating sensation noted by the
|
391 |
+
patient , even when exactly the same sequence that resulted in heating in
|
392 |
+
the first session was used . the use of mri - compatible temperature
|
393 |
+
monitors such as fibre optic temperature probes would have provided better
|
394 |
+
confirmation of possible skin temperature elevation and would not have been
|
395 |
+
affected by the rf fields . for cardiac imaging , the main problem to solve
|
396 |
+
is metallic artefact , especially on the gradient - echo sequences . like in
|
397 |
+
research performed by nazarian et al . , several scan protocols were used to
|
398 |
+
see if any yielded different effects or reduced the qualitative extent of
|
399 |
+
artefact . gradient mode was changed from normal to whisper , resulting in
|
400 |
+
slower ramping of the field and therefore diminishing the changes of the
|
401 |
+
magnetic field in time . artefacts when present were limited to blurring of
|
402 |
+
the left ventricle during cardiac scans and most yielded clinically useful
|
403 |
+
information . standard interrogation of the s - icd revealed no adverse
|
404 |
+
effects upon the functioning of the system . while no adverse effects upon
|
405 |
+
the post - scan s - icd device function were noted , not all possible
|
406 |
+
scanning protocols were tested . it should be noted that , four of the s -
|
407 |
+
icd 's were exposed to repeat mri scans without adverse effects to device
|
408 |
+
function . in addition , because the s - icd does not provide long - term
|
409 |
+
bradycardia pacing , it is assumed that pacemaker - dependent patients would
|
410 |
+
not be implanted with this system . the inhibition of the pacemaker function
|
411 |
+
during the scanning sequence and possible pacing threshold changes are a
|
412 |
+
unique concern in patients implanted with transvenous icds . this study
|
413 |
+
included only 15 patients and 22 scans done on the same 1.5 t mri scanner .
|
414 |
+
thus , even these preliminary results should only be applied to 1.5 t mri
|
415 |
+
scanners ( similarly as reported in the present literature for other
|
416 |
+
implantable devices ) . device functionality was tested immediately after
|
417 |
+
the scan but not for long - term effects . in addition , not all device
|
418 |
+
functions were tested although the s - icd system does have a beeper /
|
419 |
+
interrogation warning if battery levels or memory irregularities occur .
|
420 |
+
however , patients were scheduled for regular check - up and no defect of
|
421 |
+
the device was observed in following 725 months ( mean observation time 18
|
422 |
+
months ) . delayed enhancement mri for determining cardiac scarring was also
|
423 |
+
not tested . also , there are other anatomical areas that were not evaluated
|
424 |
+
, such as shoulder and knees . this study included only 15 patients and 22
|
425 |
+
scans done on the same 1.5 t mri scanner . thus , even these preliminary
|
426 |
+
results should only be applied to 1.5 t mri scanners ( similarly as reported
|
427 |
+
in the present literature for other implantable devices ) . device
|
428 |
+
functionality was tested immediately after the scan but not for long - term
|
429 |
+
effects . in addition , not all device functions were tested although the s
|
430 |
+
- icd system does have a beeper / interrogation warning if battery levels or
|
431 |
+
memory irregularities occur . however , patients were scheduled for regular
|
432 |
+
check - up and no defect of the device was observed in following 725 months
|
433 |
+
( mean observation time 18 months ) . delayed enhancement mri for
|
434 |
+
determining cardiac scarring was also not tested . also , there are other
|
435 |
+
anatomical areas that were not evaluated , such as shoulder and knees .
|
436 |
+
while more data are required to support a claim of mri - conditional , this
|
437 |
+
study is the study to demonstrate the feasibility of exposing s - icd
|
438 |
+
patients to mri using the scanning and monitor protocol described , with
|
439 |
+
some precautionary measures including : ( i ) programming the device therapy
|
440 |
+
off ; ( ii ) limiting the sar to 2.0 w / kg ; ( iii ) continuous monitoring
|
441 |
+
of the patients pulse oximetry and ecg by qualified personnel and especially
|
442 |
+
for any feelings of heating ; ( iv ) evaluate device function post scan ; (
|
443 |
+
v ) availability of full resuscitation facilities at the mri site . given
|
444 |
+
the variables of different mri scanners , the decision to perform mri on
|
445 |
+
patients with an implanted s - icd system should be balanced against the
|
446 |
+
potential risks . in our study , the only heating was very likely introduced
|
447 |
+
by not fully mri - compatible thermometer probe ; subjects rescanned without
|
448 |
+
the probe did not report any abnormalities during the scan of any body area
|
449 |
+
listed ( brain , cervical and lumbar spine , heart , and knee ) . this study
|
450 |
+
was supported by iga mz r nt12094/2011 , research project charles university
|
451 |
+
in prague , prvouk p34 and unce 204010/2012 . funding to pay the open access
|
452 |
+
publication charges for this article was provided by iga mz r nt12094/2011 .
|
453 |
example_title: Summarization Example 1
|
454 |
---
|
455 |
|
|
|
543 |
References
|
544 |
Hugging Face Model Hub
|
545 |
T5 Paper
|
546 |
+
Disclaimer: The model's performance may be influenced by the quality and representativeness of the data it was fine-tuned on. Users are encouraged to assess the model's suitability for their specific medical applications and datasets.
|