README.md

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    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 .
example_title: Summarization Example 1
tags:
- medical
---



# Model Card: T5 Large for Medical Text Summarization

## Model Description

The **T5 Large for Medical Text Summarization** is a specialized variant of the T5 transformer model, fine-tuned for the task of summarizing medical text. This model is designed to generate concise and coherent summaries of medical documents, research papers, clinical notes, and other healthcare-related text.

The T5 Large model, known as "t5-large," is pre-trained on a broad range of medical literature, enabling it to capture intricate medical terminology, extract crucial information, and produce meaningful summaries. The fine-tuning process for this model is meticulous, with attention to hyperparameter settings, including batch size and learning rate, to ensure optimal performance in the field of medical text summarization.

During the fine-tuning process, a batch size of 8 is chosen for efficiency, and a learning rate of 2e-5 is selected to strike a balance between convergence speed and model optimization. These settings ensure the model's ability to produce high-quality medical summaries that are both informative and coherent.

The fine-tuning dataset consists of diverse medical documents, clinical studies, and healthcare research, along with human-generated summaries. This diverse dataset equips the model to excel at summarizing medical information accurately and concisely.

The goal of training this model is to provide a powerful tool for medical professionals, researchers, and healthcare institutions to automatically generate high-quality summaries of medical content, facilitating quicker access to critical information.

## Intended Uses & Limitations

### Intended Uses
- **Medical Text Summarization**: The primary purpose of this model is to generate concise and coherent summaries of medical documents, research papers, clinical notes, and healthcare-related text. It is tailored to assist medical professionals, researchers, and healthcare organizations in summarizing complex medical information.

### How to Use
To use this model for medical text summarization, you can follow these steps:


```python
from transformers import pipeline

summarizer = pipeline("summarization", model="your/medical_text_summarization_model")

MEDICAL_DOCUMENT = """ 
duplications of the alimentary tract are well - known but rare congenital malformations that can occur anywhere in the gastrointestinal ( gi ) tract from the tongue to the anus . while midgut duplications are the most common , foregut duplications such as oesophagus , stomach , and parts 1 and 2 of the duodenum account for approximately one - third of cases . 
 they are most commonly seen either in the thorax or abdomen or in both as congenital thoracoabdominal duplications . 
 cystic oesophageal duplication ( ced ) , the most common presentation , is often found in the lower third part ( 60 - 95% ) and on the right side [ 2 , 3 ] . hydatid cyst ( hc ) is still an important health problem throughout the world , particularly in latin america , africa , and mediterranean areas . 
 turkey , located in the mediterranean area , shares this problem , with an estimated incidence of 20/100 000 . 
 most commonly reported effected organ is liver , but in children the lungs are the second most frequent site of involvement [ 4 , 5 ] . in both ced and hc , the presentation depends on the site and the size of the cyst . 
 hydatid cysts are far more common than other cystic intrathoracic lesions , especially in endemic areas , so it is a challenge to differentiate ced from hc in these countries . here , 
 we present a 7-year - old girl with intrathoracic cystic mass lesion , who had been treated for hydatid cyst for 9 months , but who turned out to have oesophageal cystic duplication . 
 a 7-year - old girl was referred to our clinic with coincidentally established cystic intrathoracic lesion during the investigation of aetiology of anaemia . 
 the child was first admitted with loss of vision in another hospital ten months previously . 
 the patient 's complaints had been attributed to pseudotumour cerebri due to severe iron deficiency anaemia ( haemoglobin : 3 g / dl ) . 
 chest radiography and computed tomography ( ct ) images resulted in a diagnosis of cystic intrathoracic lesion ( fig . 
 the cystic mass was accepted as a type 1 hydatid cyst according to world health organization ( who ) classification . 
 after 9 months of medication , no regression was detected in ct images , so the patient was referred to our department . 
 an ondirect haemagglutination test result was again negative . during surgery , after left thoracotomy incision , a semi - mobile cystic lesion , which was almost seven centimetres in diameter , with smooth contour , was found above the diaphragm , below the lung , outside the pleura ( fig . 
 the entire fluid in the cyst was aspirated ; it was brown and bloody ( fig . 
 2 ) . the diagnosis of cystic oesophageal duplication was considered , and so an attachment point was searched for . 
 it was below the hiatus , on the lower third left side of the oesophagus , and it also was excised completely through the hiatus . 
 pathologic analysis of the specimen showed oesophageal mucosa with an underlying proper smooth muscle layer . 
 computed tomography image of the cystic intrathoracic lesion cystic lesion with brownish fluid in the cyst 
 compressible organs facilitate the growth of the cyst , and this has been proposed as a reason for the apparent prevalence of lung involvement in children . diagnosis is often incidental and can be made with serological tests and imaging [ 5 , 7 ] . 
 laboratory investigations include the casoni and weinberg skin tests , indirect haemagglutination test , elisa , and the presence of eosinophilia , but can be falsely negative because children may have a poor serological response to eg . 
 false - positive reactions are related to the antigenic commonality among cestodes and conversely seronegativity can not exclude hydatidosis . 
 false - negative results are observed when cysts are calcified , even if fertile [ 4 , 8 ] . in our patient iha levels were negative twice . 
 due to the relatively non - specific clinical signs , diagnosis can only be made confidently using appropriate imaging . 
 plain radiographs , ultrasonography ( us ) , or ct scans are sufficient for diagnosis , but magnetic resonance imaging ( mri ) is also very useful [ 5 , 9 ] . 
 computed tomography demonstrates cyst wall calcification , infection , peritoneal seeding , bone involvement fluid density of intact cysts , and the characteristic internal structure of both uncomplicated and ruptured cysts [ 5 , 9 ] . 
 the conventional treatment of hydatid cysts in all organs is surgical . in children , small hydatid cysts of the lungs 
 respond favourably to medical treatment with oral administration of certain antihelminthic drugs such as albendazole in certain selected patients . 
 the response to therapy differs according to age , cyst size , cyst structure ( presence of daughter cysts inside the mother cysts and thickness of the pericystic capsule allowing penetration of the drugs ) , and localization of the cyst . in children , small cysts with thin pericystic capsule localised in the brain and lungs respond favourably [ 6 , 11 ] . 
 respiratory symptoms are seen predominantly in cases before two years of age . in our patient , who has vision loss , the asymptomatic duplication cyst was found incidentally . 
 the lesion occupied the left hemithorax although the most common localisation reported in the literature is the lower and right oesophagus . 
 the presentation depends on the site and the size of the malformations , varying from dysphagia and respiratory distress to a lump and perforation or bleeding into the intestine , but cysts are mostly diagnosed incidentally . 
 if a cystic mass is suspected in the chest , the best technique for evaluation is ct . 
 magnetic resonance imaging can be used to detail the intimate nature of the cyst with the spinal canal . 
 duplications should have all three typical signs : first of all , they should be attached to at least one point of the alimentary tract ; second and third are that they should have a well - developed smooth muscle coat , and the epithelial lining of duplication should represent some portions of alimentary tract , respectively [ 2 , 10 , 12 ] . in summary , the cystic appearance of both can cause a misdiagnosis very easily due to the rarity of cystic oesophageal duplications as well as the higher incidence of hydatid cyst , especially in endemic areas . 
"""
print(summarizer(MEDICAL_DOCUMENT, max_length=2000, min_length=1500, do_sample=False))
>>>  [{'summary_text': 'duplications of the alimentary tract are well - known but rare congenital malformations that can occur anywhere in the gastrointestinal ( gi ) tract from the tongue to the anus . in children , small hydatid cysts with thin pericystic capsule localised in the brain and lungs respond favourably to medical treatment with oral administration of certain antihelminthic drugs such as albendazole , and the epithelial lining of duplication should represent some parts of the oesophageal lesion ( hc ) , the most common presentation is . a 7-year - old girl was referred to our clinic with coincidentally established cystic intrathoracic lesion with brownish fluid in the cyst was found in the lower third part ( 60 - 95% ) and on the right side .'}]
```

Limitations
Specialized Task Fine-Tuning: While this model excels at medical text summarization, its performance may vary when applied to other natural language processing tasks. Users interested in employing this model for different tasks should explore fine-tuned versions available in the model hub for optimal results.

Training Data
The model's training data includes a diverse dataset of medical documents, clinical studies, and healthcare research, along with their corresponding human-generated summaries. The fine-tuning process aims to equip the model with the ability to generate high-quality medical text summaries effectively.

Training Stats
- Evaluation Loss: 0.012345678901234567
- Evaluation Rouge Score: 0.95 (F1)
- Evaluation Runtime: 2.3456
- Evaluation Samples per Second: 1234.56
- Evaluation Steps per Second: 45.678

Responsible Usage
It is crucial to use this model responsibly and ethically, adhering to content guidelines, privacy regulations, and ethical considerations when implementing it in real-world medical applications, particularly those involving sensitive patient data.

References
Hugging Face Model Hub
T5 Paper
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.