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license: apache-2.0 |
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language: |
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- en |
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pipeline_tag: summarization |
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widget: |
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- text: 'the need for magnetic resonance imaging ( mri ) in patients with an implanted |
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pacemaker or implantable cardioverter - defibrillator ( icd ) is a growing clinical |
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issue . it is estimated that as many as 75% of active cardiac device recipients |
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will become indicated for mri . currently , the vast majority of such devices |
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are contraindicated for use with an mri . in european heart rhythm association |
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survey , published recently for non - mri - certified icds ( 0.51.5 t field strength |
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) , the totally subcutaneous icd ( s - icd ) system , an implantable defibrillator |
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with no leads that touch the heart , has recently been demonstrated to be a safe |
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and effective defibrillator option for patients at risk for sudden cardiac death |
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. it provides shock therapy and post - shock pacing therapy , but no long - term |
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bradycardia pacing . although it has been shown as an alternative to the standard |
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transvenous icd , its compatibility with mri remains unclear . various types of |
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clinical mri systems currently use a superconductive magnet that creates a static |
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magnetic field strength , typically 1.5 or 3 t. the use of mri with most pacemakers |
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and icds is considered a contraindication due to potential hazards , including |
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heating of the electrode that resides in or on the heart , damage to myocardium |
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, elevation of pacing thresholds , unintended induction of ventricular tachycardia |
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( vt ) or ventricular fibrillation ( vf ) , pacing inhibition , permanent device |
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malfunction , and distortion of the mri scan . recently , mr - conditional. mr |
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- conditional indicates a lack of known hazards in a specified mri environment |
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with specified conditions of use . due to the variety of mri scanners and scanning |
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protocols , it is not practical to test even a single device under all conditions |
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. hence , mr - conditional labelling dictates that the device is safe for use |
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under certain scanning conditions , as well as how the cardiac device should be |
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programmed before an exposure to the magnetic field in a mri scanner . the literature |
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, although limited , provides some guidance for imaging patients with implanted |
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pacemakers or icds that do not have mr - conditional labelling . this single - |
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centre prospective non - controlled study describes the first use of mri in patients |
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with an implanted s - icd . patients with implanted s - icd systems ( boston scientific |
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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 |
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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 |
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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 |
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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 |
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/ 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 |
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- 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 .' |
|
example_title: Summarization Example 1 |
|
tags: |
|
- medical |
|
- llama-cpp |
|
- gguf-my-repo |
|
base_model: Falconsai/medical_summarization |
|
--- |
|
|
|
# fernandoruiz/medical_summarization-Q4_0-GGUF |
|
This model was converted to GGUF format from [`Falconsai/medical_summarization`](https://huggingface.co/Falconsai/medical_summarization) using llama.cpp via the ggml.ai's [GGUF-my-repo](https://huggingface.co/spaces/ggml-org/gguf-my-repo) space. |
|
Refer to the [original model card](https://huggingface.co/Falconsai/medical_summarization) for more details on the model. |
|
|
|
## Use with llama.cpp |
|
Install llama.cpp through brew (works on Mac and Linux) |
|
|
|
```bash |
|
brew install llama.cpp |
|
|
|
``` |
|
Invoke the llama.cpp server or the CLI. |
|
|
|
### CLI: |
|
```bash |
|
llama-cli --hf-repo fernandoruiz/medical_summarization-Q4_0-GGUF --hf-file medical_summarization-q4_0.gguf -p "The meaning to life and the universe is" |
|
``` |
|
|
|
### Server: |
|
```bash |
|
llama-server --hf-repo fernandoruiz/medical_summarization-Q4_0-GGUF --hf-file medical_summarization-q4_0.gguf -c 2048 |
|
``` |
|
|
|
Note: You can also use this checkpoint directly through the [usage steps](https://github.com/ggerganov/llama.cpp?tab=readme-ov-file#usage) listed in the Llama.cpp repo as well. |
|
|
|
Step 1: Clone llama.cpp from GitHub. |
|
``` |
|
git clone https://github.com/ggerganov/llama.cpp |
|
``` |
|
|
|
Step 2: Move into the llama.cpp folder and build it with `LLAMA_CURL=1` flag along with other hardware-specific flags (for ex: LLAMA_CUDA=1 for Nvidia GPUs on Linux). |
|
``` |
|
cd llama.cpp && LLAMA_CURL=1 make |
|
``` |
|
|
|
Step 3: Run inference through the main binary. |
|
``` |
|
./llama-cli --hf-repo fernandoruiz/medical_summarization-Q4_0-GGUF --hf-file medical_summarization-q4_0.gguf -p "The meaning to life and the universe is" |
|
``` |
|
or |
|
``` |
|
./llama-server --hf-repo fernandoruiz/medical_summarization-Q4_0-GGUF --hf-file medical_summarization-q4_0.gguf -c 2048 |
|
``` |
|
|
