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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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- 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.
 
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+ - text: >-
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+ the need for magnetic resonance imaging ( mri ) in patients with an
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+ implanted pacemaker or implantable cardioverter - defibrillator ( icd ) is a
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+ growing clinical issue . it is estimated that as many as 75% of active
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+ cardiac device recipients will become indicated for mri . currently , the
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+ vast majority of such devices are contraindicated for use with an mri . in
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+ european heart rhythm association survey , published recently for non - mri
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+ - certified icds ( 0.51.5 t field strength ) , the totally subcutaneous icd
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+ ( s - icd ) system , an implantable defibrillator with no leads that touch
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+ 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
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  ---
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  References
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  Hugging Face Model Hub
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  T5 Paper
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+ 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.