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 .
 aimsour aim was to evaluate the potential for safely imaging patients with a new type of implantable cardioverter - defibrillator called the subcutaneous implantable cardioverter - defibrillator ( s - icd ) in a 1.5 t magnetic resonance imaging ( mri ) scanner . with the increasing number of patients with cardiac implantable devices who are indicated for mri 
 , there is a growing need for establishing mri compatibility of cardiac implantable devices.methods and resultspatients with implanted s - icd systems underwent one or more types of anatomical mri scans . 
 the s - icd was programmed off and patients were monitored throughout the imaging procedure . device function was evaluated pre- and post - scan . 
 patients were asked to report immediately any pain , torqueing movement , or heating sensation in the area of the pocket or electrode . 
 fifteen patients underwent a total of 22 examinations at 1.5 t. scans included brain , spine , knee , and heart . 
 two patients were re - scanned due to complaints of heating over the can during lumbar scans , which was caused by a thermistor probe placed on the skin to measure skin temperature . 
 all the remaining scans occurred without incident . 
 no evidence of device malfunction was observed.conclusionthis study is the first to domonstrate the feasibility of exposing s - icd patients to mri using the scanning and monitoring protocol described . 
 more data are required to support s - icd as a mri conditional device . 
Introduction
Methods
Patient selection
Magnetic resonance imaging
Device assessment
Results
Subcutaneous implantable cardioverter-defibrillator status
Image artefacts
Discussion
Limitations
Conclusions
Funding