Delayed Contrast Enhancement Research Articles

Usefulness of Cardiac Computed Tomographic Delayed Contrast Enhancement of the Left Atrial Appendage Before Pulmonary Vein Ablation

Left atrial appendage (LAA) contrast filling defects are commonly found in patients undergoing multidetector cardiac computed tomography (CCT) before catheter ablation of atrial fibrillation. Delayed CCT allows quantification of the LAA delayed/initial attenuation ratio and improves accuracy for LAA thrombus detection, which may obviate routine transesophageal echocardiography (TEE) before ablation. CCT with contrast-enhanced scans (initial CCT) and with noncontrast-enhanced scans (delayed CCT) was performed in 176 patients. LAA was evaluated for filling defects. LAA apex, left atrial (LA) body, and ascending aorta (AA) attenuations (Hounsfield units) were measured on initial and delayed cardiac computed tomograms to calculate LAA, LA, LAA/LA, and LAA/AA attenuation ratios. LAA, initial LAA/LA, and initial LAA/AA attenuation ratios differed significantly in patients with versus without filling defects on cardiac computed tomogram, those with atrial fibrillation versus normal sinus rhythm, and those with abnormal left ventricular ejection fraction versus larger LA volumes (p <0.05). In 70 patients (40%) who underwent TEE, 13 LAA filling defects were seen on initial cardiac computed tomogram. Two defects persisted on delayed cardiac computed tomogram and thrombus was confirmed on transesophageal echocardiogram. Sensitivity, specificity, and positive and negative predictive values of initial CCT for LAA thrombi detection were 100%, 84%, 15%, and 100%, respectively. With delayed CCT these values increased to 100%. Intraobserver and interobserver reproducibilities for cardiac computed tomographic measurements were good (intraclass correlation 0.72 to 0.97, kappa coefficients 0.93 to 1.00). In conclusion, delayed CCT provided an increase in diagnostic accuracy of CCT for detection of LAA thrombus in patients with atrial fibrillation before ablation, which may decrease the need for routine TEE before the procedure.

Imaging Study of Ventricular Scar in Arrhythmogenic Right Ventricular Cardiomyopathy

Background— The hallmark lesion of arrhythmogenic right ventricular cardiomyopathy (ARVC) is fibrofatty scar replacement. We compared endocardial voltage mapping (EVM) and contrast-enhanced cardiac magnetic resonance (CE-CMR) for imaging scar lesions in ARVC patients. Methods and Results— We studied 23 consecutive ARVC patients (16 males; mean age, 38±12 years) who underwent RV EVM and CE-CMR and 37 control subjects. In 21 (91%) of 23 ARVC patients, RV EVM was abnormal, with a total of 45 electroanatomical scars (EAS): 17 (38%) in the inferobasal region, 12 (26.6%) in the anterolateral region, 8 (17.7%) in the RV outflow tract (RVOT), and 8 (17.7%) in the apex. RV delayed contrast enhancement (DCE) was found in 9 (39%) of 23 patients, with a total of 23 RV DCE scars: 4 (17.4%) in the inferobasal region, 9 (39.1%) in the anterolateral region, 4 (17.4%) in the RVOT, and 6 (26.1%) in the apex. There was a mismatch in 24 RV scars, with 22 EAS not confirmed by DCE and 2 DCE scars (both in the RVOT) undetected by EVM. In 9 (75%) of 12 patients with abnormal RV EVM/normal RV DCE, ≥1 DCEs were identified in the left ventricle (LV). Overall, ventricular DCE was detected in 78% of patients. No control subjects showed either EAS or DCE. Conclusions— EVM and CE-CMR allow identification of RV scar lesions in most ARVC patients. CE-CMR is less sensitive than EVM in identifying RV scar lesions. The high prevalence of LV DCE confirms the frequent biventricular involvement and indicates the diagnostic relevance of LV scar detection by CE-CMR.

Delayed contrast-enhanced cardiac MRI at an open 1.0T MR-system comparison of conventional segmented 3D gradient echo and phase-sensitive inversion recovery sequences: initial results

Background Delayed contrast enhanced (DE) cardiac MR imaging (cMRI) has become the gold standard for the in vivo detection and quantification of myocardial infarcts (MI). Up to now, cMRI had to be performed in a closed bore environment due to technical constraints of the existing open low-field MR scanners. The introduction of an open 1.0T MR-system with high gradient performance has paved the way for cardiac imaging, which may be beneficial in critically ill and claustrophobic patients as well as during stress examinations and MR-guided interventions. The aim of this study was to evaluate image quality, scar/myocardium-contrast and assess feasibility of delayed contrast enhanced cMRI using a 1) breath hold (BH) 3 dimensional (3D) Inversion Recovery (IR), 2) BH phase-sensitive IR (PSIR), and 3) a respiratory triggered (RT) PSIR sequence at an open MR-system. Methods 41 patients (11 female, 30 male; age 57+/-15 years) with known or suspected MI underwent viability imaging 10 min after i.v. application of Gd-DTPA (0.2 mmol/kg BW) at an open MRI system (Panorama HFO 1.0 Tesla, Philips Healthcare, Best, Netherlands). DE cMRI with complete coverage of the left-ventricular myocardium in short-axis (SA) slices was acquired using three different sequences and approaches: 1) A conventional k-space segmented 3D T1-weighted inversion-recovery-prepared gradient-echo sequence (in-plane resolution 1.33x1.33 mm2, slice thickness 5 mm) was performed. The inversion delay time TI was iteratively adjusted to null the signal from normal myocardium. Additionally, a fast multislice single-shot 3D PSIR sequence was performed in 2) BH technique (in-plane resolution 1.51x1.71 mm2, slice thickness 10 mm, SENSE factor 2 and 3) respiratory triggered (in-plane resolution 1.8x1.8 mm2, slice thickness 10 mm). Image quality of DE was rated on a 4-point grading scale. Contrast (C=SIscar/SImyo) was calculated and area of DE was assessed in % of LV mass. Results There was no statistical significant difference in image quality using BH 3D IR, BH PSIR and RT PSIR (3.71 +/-0.46; 3.27+/-0.61, 3.36+/-0.87, p<0.05), respectively. No infarcts were missed and agreement between the three approaches regarding infarct extent (BH 3D IR 5.47+/-9.08% vs. BH PSIR 5.26+/-8.89% vs. RT PSIR 5.59+/-8.85%, p< 0.05) was high. Contrast for 3D BH IR, BH PSIR and RT PSIR was 10.4+/-3.3 and 11.8+/-3.0, and 12.6+/-1.9, respectively. Conclusions Delayed contrast enhanced cMRI is feasible at an open 1.0T MRI system in a clinical setting and offers excellent image quality. Respiratory triggered PSIR findings correlate well with breath hold 3D IR and PSIR sequences for the detection and extent of myocardial infarcts.

Effect of age on exercise capacity and cardiac reserve in patients with pulmonary atresia with intact ventricular septum after biventricular repair

OBJECTIVESIn patients with pulmonary atresia with intact ventricular septum (PAIVS), biventricular repair is considered to be the optimal treatment option in the absence of significant right ventricular (RV) hypoplasia. However, long-term clinical outcome studies are limited. We evaluated exercise capacity and cardiac function during pharmacological stress in children and young adults with PAIVS after biventricular repair.METHODSTen PAIVS patients after biventricular repair, with a median age of 12 years (range 9-42 years), underwent a cardiopulmonary exercise test, dobutamine stress magnetic resonance imaging (DS-MRI) and delayed contrast enhancement (DCE) MRI.RESULTSThe patients' ages negatively correlated with exercise capacity (r = -0.72, P = 0.01) as well as left (LV) and RV stroke volume (SV) response to pharmacological stress (r = -0.72, P = 0.02; and r = -0.64, P = 0.04; respectively), Furthermore, older age was associated with decreased RV E/A volume ratio and increased pulmonary late diastolic forward flow percentage (r = 0-0.65, P = 0.04, r = 0.66, P = 0.03, respectively). RV E/A volume ratio positively correlated with RV-SV response to DS-MRI (r = 0.77, P = 0.009). and O(2)-pulse during physical stress correlated with biventricular SV response to DS-MRI. No RV or LV ventricular myocardial fibrosis was detected.CONCLUSIONSIn PAIVS patients after biventricular repair exercise capacity and cardiac reserve decrease with age. These findings appear to be related to impaired diastolic RV function and decreased RV filling, indicating that the function of the relatively small RV deteriorates with time

Prognostic Value of Myocardial Contrast Delayed Enhancement With 64-Slice Multidetector Computed Tomography After Acute Myocardial Infarction

This study evaluated the clinical value of myocardial contrast delayed enhancement (DE) with multidetector computed tomography (MDCT) for predicting clinical outcome after acute myocardial infarction (AMI). Although some studies have described the use of MDCT for assessment of myocardial viability after AMI, clinical experience remains limited. In 102 patients with first AMI, 64-slice MDCT without iodine reinjection was performed immediately following successful percutaneous coronary intervention (PCI). We measured the size of myocardial contrast DE on MDCT and compared it with clinical outcome. Primary composite cardiac events were cardiac death or hospitalization for worsening heart failure. Among the 102 patients (24 ± 10 months follow-up), 19 patients experienced primary composite cardiac events (cardiac death, n = 7; heart failure, n = 12). Kaplan-Meier analysis showed higher risk of cardiac events for patients in the third tertile of myocardial contrast DE size (≥ 36 g) than for those in the other 2 tertiles (p < 0.0001). Multivariable Cox proportional hazards regression analysis indicated that myocardial contrast DE size (adjusted hazard ratio [HR] for tertile 3 vs. 1: 16.1, 95% confidence interval [CI]: 1.45 to 72.4, p = 0.022; HR for tertile 3 vs. 2: 5.06, 95% CI: 1.25 to 22.7, p = 0.039) was a significant independent predictor for cardiac events after adjustment for Thrombolysis In Myocardial Infarction risk score, left ventricular ejection fraction, total defect score on single-photon emission CT with technetium tetrofosmin, and transmural extent of myocardial contrast DE on MDCT. Myocardial contrast DE size on MDCT immediately after primary PCI may provide promising information for predicting clinical outcome in patients with AMI.

Effect of age on exercise capacity and cardiac reserve in patients with pulmonary atresia with intact ventricular septum after biventricular repair

In patients with pulmonary atresia with intact ventricular septum (PAIVS), biventricular repair is considered to be the optimal treatment option in the absence of significant right ventricular (RV) hypoplasia. However, long-term clinical outcome studies are limited. We evaluated exercise capacity and cardiac function during pharmacological stress in children and young adults with PAIVS after biventricular repair. Ten PAIVS patients after biventricular repair, with a median age of 12 years (range 9-42 years), underwent a cardiopulmonary exercise test, dobutamine stress magnetic resonance imaging (DS-MRI) and delayed contrast enhancement (DCE) MRI. The patients' ages negatively correlated with exercise capacity (r=-0.72, P=0.01) as well as left (LV) and RV stroke volume (SV) response to pharmacological stress (r=-0.72, P=0.02; and r=-0.64, P=0.04; respectively), Furthermore, older age was associated with decreased RV E/A volume ratio and increased pulmonary late diastolic forward flow percentage (r=0-0.65, P=0.04, r=0.66, P=0.03, respectively). RV E/A volume ratio positively correlated with RV-SV response to DS-MRI (r=0.77, P=0.009). and O2-pulse during physical stress correlated with biventricular SV response to DS-MRI. No RV or LV ventricular myocardial fibrosis was detected. In PAIVS patients after biventricular repair exercise capacity and cardiac reserve decrease with age. These findings appear to be related to impaired diastolic RV function and decreased RV filling, indicating that the function of the relatively small RV deteriorates with time.

Prediction of functional recovery after revascularization in patients with chronic ischemic myocardial dysfunction

In patients with chronic ischemic myocardial dysfunction, perfusable tissue index (PTI) obtained with positron emission tomography using oxygen-15-labeled water and carbon monoxide as tracers is inversely related to the extent of myocardial scar (nonperfusable tissue). Delayed contrast-enhanced (DCE) magnetic resonance imaging (MRI) accurately depicts the regional extent of myocardial fibrosis and predicts functional recovery after revascularization in patients with ischemic cardiomyopathy. Our aim was to compare PTI as a viability marker with DCE MRI. Fourteen patients with ischemic left ventricular dysfunction were studied with positron emission tomography, using oxygen-15-labeled water and carbon monoxide as tracers, and with contrast-enhanced MRI. Functional improvement occurred in 38 of initially dysfunctional, revascularized segments (56%). Mean PTI was 1.04 ± 0.20 in the improved segments versus 0.85 ± 0.21 in the group without functional improvement (P<0.001). The areas under the receiver operator characteristics curves of PTI and DCE MRI were 0.7 and 0.74, respectively (P=not significant). Cutoff value of 25% DCE allowed correct identification of 82% segments with reversible dysfunction and 64% segments without reversible dysfunction. A threshold of 0.89 for PTI yielded the best diagnostic accuracy with sensitivity and specificity values of 76 and 54%, respectively. PTI can identify viable myocardium and predict improvement in regional function after revascularization in patients with chronic ischemic left ventricular dysfunction. Its diagnostic accuracy is comparable with that of DCE MRI.

Infarct detection with a comprehensive cardiac CT protocol

Cardiac CT has the potential to offer comprehensive infarct detection by assessing regional wall motion abnormalities (RWMAs), rest perfusion defects (RPDs), and delayed contrast enhancement (DCE). However, the diagnostic accuracy of these techniques for the detection of myocardial infarction (MI) is unknown. Forty-eight patients with intermediate-to-high probability for coronary artery disease after single-photon emitting CT myocardial perfusion imaging were prospectively enrolled for a research comprehensive 64-detector row dual-source cardiac CT protocol that included cine images for RWMA, first-pass images for RPD, and delayed images for DCE. Blinded readers independently assessed each technique. Subsequently, a final combined analysis (cine + rest + DCE) was performed. The universal definition for MI by the 2007 American Heart Association task force was used as the "gold standard." Twenty-four of 48 patients (50%) had infarct by the universal definition. The combined CT analysis was most accurate (90%) with the highest per-patient sensitivity (88%) and specificity (92%) versus individual assessments (RWMA, 79% and 88%; RPD, 67% and 92%; DCE, 79% and 88%). Similar findings were observed on a per-vessel basis analysis. A combination of DCE and cine showed a good accuracy (85%) and high sensitivity (92%). Infarct detection with CT is feasible with overall good diagnostic accuracy compared with the universal definition. A combined evaluation that included all techniques (cine, RPD, and DCE) had the highest diagnostic accuracy. These findings may have implications when designing future clinical and research CT protocols for optimal infarct detection.

Comparison of Real-Time Three-Dimensional Speckle Tracking to Magnetic Resonance Imaging in Patients With Coronary Heart Disease

This study compared strain values from 2-dimensional (2D) and real-time 3-dimensional (3D) speckle tracking with hyperenhancement transmural extent by magnetic resonance imaging (MRI). The study included 18 control subjects (mean age 51 ± 10 years) and 25 patients (20 men, mean age 62 ± 16 years) with ischemic left ventricular (LV) dysfunction (mean LV ejection fraction 41 ± 9%) referred for viability assessment using MRI. Longitudinal, radial, and circumferential strain values were computed using 2D speckle tracking. From analysis of 3D speckle tracking, conventional strain markers (longitudinal, radial, and circumferential) and 2 new 3D strain indexes (area and 3D strains) were obtained from apical view 3D datasets. A hyperenhancement transmural extent segment (16-segment model) was defined as delayed contrast enhancement >50%. Overall, 661 of 688 segments (96%) were analyzable by MRI and 3D speckle tracking. All 3D strain components in hyperenhancement transmural extent segments (n = 154) were lower than in nontransmural necrosis (n = 219) and control (n = 288) segments. Longitudinal strain by 3D, but not by 2D, differentiated nontransmural segments with scar <25%. All 3D global strain indexes correlated with LV ejection fraction (r(2) = 0.67 to 0.26, p <0.05 for all comparisons), whereas only area, longitudinal, and circumferential 3D strains correlated with global scar extent. The best reproducibility was provided by 3D longitudinal (6%) and area (8%) strains. In conclusion, longitudinal and area strains by 3D speckle tracking provide an accurate and reproducible measurement of myocardial deformation that correlate with infarct size in patients with ischemic LV dysfunction.

Cardiogenic shock following administration of propofol and fentanyl in a healthy woman: a case report

IntroductionCardiogenic shock is very uncommon in healthy people. The differential diagnosis for patients with acute heart failure in previously healthy hearts includes acute myocardial infarction and myocarditis. However, many drugs can also depress myocardial function. Propofol and fentanyl are frequently used during different medical procedures. The cardiovascular depressive effect of both drugs has been well established, but the development of cardiogenic shock is very rare when these agents are used.Case presentationAfter a minor surgical intervention, a 32-year-old Caucasian woman with no significant medical history went into sudden hemodynamic deterioration due to acute heart failure. An urgent echocardiogram showed severe biventricular dysfunction and an estimated left ventricular ejection fraction of 20%. Extracorporeal life support and mechanical ventilation were required. Five days later her ventricular function had fully recovered, which allowed the progressive withdrawal of medical treatment. Prior to her hospital discharge, cardiac MRI showed neither edema nor pathological deposits on the delayed contrast enhancement sequences. At her six-month follow-up examination, the patient was asymptomatic and did not require treatment.ConclusionAlthough there are many causes of cardiogenic shock, the presence of abrupt hemodynamic deterioration and the absence of a clear cause could be related to the use of propofol and fentanyl.

Computed tomography stress myocardial perfusion imaging in patients considered for revascularization: a comparison with fractional flow reserve

Adenosine stress computed tomography myocardial perfusion imaging (CTP) is an emerging non-invasive method for detecting myocardial ischaemia. Its value when compared with fractional flow reserve (FFR), a highly accurate index of ischaemia, is unknown. Our aim was to determine the diagnostic accuracy of CTP and its incremental value when used with computed tomography coronary angiography (CTA) for detecting ischaemia compared with FFR. Forty-two patients (126 vessel territories), who had at least one ≥50% angiographic stenosis on invasive angiography considered for non-urgent revascularization, were included and underwent FFR and CT assessment, including CTP, delayed contrast enhancement scan and CTA all acquired using 320-detector row CT, and prospective ECG gating. Fractional flow reserve was determined in 86 territories subtended by vessels with ≥50% stenosis upon visual assessment. Fractional flow reserve ≤0.8 was considered to indicate significant ischaemia. Computed tomography myocardial perfusion imaging correctly identified 31/41 (76%) ischaemic territories and 38/45 (84%) non-ischaemic territories. Per-vessel territory sensitivity, specificity, positive, and negative predictive values of CTP were 76, 84, 82, and 79%, respectively. The combination of a ≥50% stenosis on CTA and perfusion defect on CTP was 98% specific for ischaemia, while the presence of <50% stenosis on CTA and normal perfusion on CTP was 100% specific for exclusion of ischaemia. Mean radiation for CTP and combined CT was 5.3 and 11.3 mSv, respectively. Computed tomography myocardial perfusion imaging is moderately accurate in identifying perfusion defects associated with ischaemia as assessed by FFR in patients considered for revascularization. In territories, where CTA and CTP are concordant, CTA/CTP is highly accurate in the detection and exclusion of ischaemia. This is achievable with acceptable radiation exposure using 320-detector row CT and prospective ECG gating.

Relation of Coronary Microvascular Dysfunction in Hypertrophic Cardiomyopathy to Contractile Dysfunction Independent from Myocardial Injury

We studied the spatial relations among hyperemic myocardial blood flow (hMBF), contractile function, and morphologic tissue alterations in 19 patients with hypertrophic cardiomyopathy (HC). All patients were studied with oxygen-15 water positron emission tomography during rest and adenosine administration to assess myocardial perfusion. Cardiovascular magnetic resonance was performed to derive delayed contrast-enhanced images and to calculate contractile function (E(cc)) with tissue tagging. Eleven healthy subjects underwent similar positron emission tomographic and cardiovascular magnetic resonance scanning protocols and served as a control group. In the HC group, hMBF averaged 2.46 ± 0.91 ml/min/g and mean E(cc) was -14.7 ± 3.4%, which were decreased compared to the control group (3.97 ± 1.48 ml/min/g and -17.7 ± 3.2%, respectively, p <0.001 for the 2 comparisons). Delayed contrast enhancement (DCE) was present only in patients with HC, averaging 6.2 ± 10.3% of left ventricular mass. In the HC group, E(cc) and DCE in the septum (-13.7 ± 3.6% and 10.2 ± 13.6%) significantly differed from the lateral wall (-16.0 ± 2.8% and 2.4 ± 5.9%, p <0.001 for the 2 comparisons). In general, hMBF and E(cc) were decreased in segments displaying DCE compared to nonenhanced segments (p <0.001 for the comparisons). In the HC group, univariate analysis revealed relations of hMBF to E(cc) (r = -0.45, p <0.001) and DCE (r = -0.31, p <0.001). Multivariate analysis revealed that E(cc) was independently related to hMBF (beta -0.37, p <0.001) and DCE (beta 0.28, p <0.001). In conclusion, in HC hMBF is impaired and related to contractile function independent from presence of DCE. When present, DCE reflected a progressed disease state as characterized by an increased perfusion deficit and contractile dysfunction.

A novel method for quantitating delayed enhancement of the left atrium

Delayed contrast enhancement of the left atrium (DE-LA) in patients with atrial fibrillation (AF) has been reported to correlate well with outcomes after catheter ablation of AF. Currently utilized methods for DE-LA assessment require intensive post-processing and significant user-defined thresholding to obtain meaningful results.

Gene therapy with iNOS enhances regional contractility and reduces delayed contrast enhancement in a model of postischemic congestive heart failure

The purpose of this study was to evaluate the effect of transient local myocardial gene transfer of iNOS on cardiac function in a large mammal animal model of heart failure induced by chronic ischemia. Chronic myocardial ischemia was induced using a minimally invasive model in 16 landrace pigs. Upon demonstration of heart failure, eight animals were treated with liposome-mediated iNOS-gene-transfer by local intramyocardial injection; eight animals received a sham procedure to serve as control. The transmurality of late enhancement (control: 46.4%, iNOS: 35.9%; p < 0.05) was significantly decreased in the ischemic area in the iNOS-treated group. Wall thickness at end-systole (6.8 mm vs. 5.9 mm, p < 0.001) and at end-diastole (5.4 mm vs. 4.2 mm, p < 0.001) were significantly higher in the therapy group. Additionally, the regional wall motion at the level of the ischemic region was 3.5 mm in the therapy group while it was significantly less (3.0 mm, p < 0.001) in the control group. Our findings demonstrate that transient iNOS overexpression potentially leads to a significant decrease of regional late enhancement with a positive effect on regional cardiac function in the ischemic area in a large animal model of postischemic heart failure.

Documenting the location of systematic transrectal ultrasound-guided prostate biopsies: correlation with multi-parametric MRI.

During transrectal ultrasound (TRUS)-guided prostate biopsies, the actual location of the biopsy site is rarely documented. Here, we demonstrate the capability of TRUS-magnetic resonance imaging (MRI) image fusion to document the biopsy site and correlate biopsy results with multi-parametric MRI findings. Fifty consecutive patients (median age 61 years) with a median prostate-specific antigen (PSA) level of 5.8 ng/ml underwent 12-core TRUS-guided biopsy of the prostate. Pre-procedural T2-weighted magnetic resonance images were fused to TRUS. A disposable needle guide with miniature tracking sensors was attached to the TRUS probe to enable fusion with MRI. Real-time TRUS images during biopsy and the corresponding tracking information were recorded. Each biopsy site was superimposed onto the MRI. Each biopsy site was classified as positive or negative for cancer based on the results of each MRI sequence. Sensitivity, specificity, and receiver operating curve (ROC) area under the curve (AUC) values were calculated for multi-parametric MRI. Gleason scores for each multi-parametric MRI pattern were also evaluated. Six hundred and 5 systemic biopsy cores were analyzed in 50 patients, of whom 20 patients had 56 positive cores. MRI identified 34 of 56 positive cores. Overall, sensitivity, specificity, and ROC area values for multi-parametric MRI were 0.607, 0.727, 0.667, respectively. TRUS-MRI fusion after biopsy can be used to document the location of each biopsy site, which can then be correlated with MRI findings. Based on correlation with tracked biopsies, T2-weighted MRI and apparent diffusion coefficient maps derived from diffusion-weighted MRI are the most sensitive sequences, whereas the addition of delayed contrast enhancement MRI and three-dimensional magnetic resonance spectroscopy demonstrated higher specificity consistent with results obtained using radical prostatectomy specimens.

Interventional PFO Closure Using the Premere Device: Australian Experience

Introduction: PFO has been described in 25–30% of adults. Prevalence increases in cryptogenic stroke. Interventional closure is often used for prevention of recurrent paradoxical embolisation and stroke. Premere device is specifically designed for PFOclosure.Key features include limited material on left side, adjustable length tether and convenient placement control. Methods: Multicentre prospective observational registry. Twenty-five patients with PFO and history of at least one thromboembolic event (cryptogenic stroke, TIA or peripheral embolism) underwent percutaneous closure using 25mm device. Mean follow up with echocardiography was 13± 9.27 months. Outcomes evaluated included incidenceof stroke/TIA, closure successanddevice related adverse events. Results: Twenty-five patients (52% women, age 44.68± 12.10) underwent PFO closure. Mean PFO size ity post STEMI. We assessed the hypothesis that intracoronary-ECG (IC-ECG) is a valid surrogate of hyperaemic-blood-flow and the extent of myocardial injury by cardiac magnetic resonance (CMR) in STEMI. Methods: We performed ST-segment analysis on ICECG prior to and immediately after achieving successful patency of the infarct related artery (IRA) during primaryPCI. The IC-ECGs were acquired by connecting an ECG monitor to the angioplasty guidewire whilst situated distally within the IRA. CTFC measurements were analysed offline. Delayed contrast enhancement CMR was performed at 3 and 90 days post primary-PCI. Results: Fifty-three STEMI patients (age 60± 10 years; 81% male) were prospectively enrolled. Despite restoration of TIMI 3 flow in 96% of patients, only 53% achieved a CTFC of 1mm successfully predicted 70% of patients with hyperaemic blood flow (p= 0.028). Immediate IC-ECG resolution >1mm also correlated with smaller infarct size (p= 0.012), peak creatinine kinase (p= 0.021) and better ejection fraction at 90 days (p= 0.038). Conclusions: Intracoronary-ECG is a novel and imme-

MRI of Cardiac Involvement in Transthyretin Familial Amyloid Polyneuropathy

The purpose of this study was to evaluate cardiac MRI features in a group of patients with transthyretin familial amyloid polyneuropathy (FAP). Sixteen patients with transthyretin FAP underwent 2D echocardiography with Doppler examination, cardiac MRI, and (99m)Tc-diphosphonate (DPD) scintigraphy. Four patients had peripheral polyneuropathy, three had carpal tunnel syndrome, one patient had symptoms and signs of heart failure, and eight patients had no symptoms but had a family history of FAP. At MRI, cardiac function parameters and delayed contrast enhancement findings were evaluated. Six patients had cardiac radiotracer uptake at scintigraphy (FAP cardiac group), and 10 patients had no cardiac uptake (FAP noncardiac group). The FAP cardiac group included the four patients with peripheral neuropathy, one patient with carpal tunnel syndrome, and the only patient with heart failure. At MRI, abnormal contrast enhancement was found in all patients with positive scintigraphic findings and in no patient with negative scintigraphic findings. All patients had involvement of the left ventricle and other chambers or structures (atria, right ventricle, tricuspid valve leaflets). Left ventricular contrast enhancement was focal in four patients, subendocardial circumferential in one patient, and diffuse in one patient. The only patient with signs of heart failure had circumferential subendocardial enhancement. Cardiac contrast-enhanced MRI can be used to identify cardiac amyloidosis in patients with FAP who do not have clinical signs of heart involvement. In these patients, the typical subendocardial circumferential pattern of contrast enhancement is rare. We observed unusual enhancement patterns as focal or diffuse left ventricular enhancement accompanied by enhancement of the atria, tricuspid valve, or right ventricle.

Percent infarct mapping for delayed contrast enhancement magnetic resonance imaging to quantify myocardial viability by Gd(DTPA)

To demonstrate the advantages of signal intensity percent-infarct-mapping (SI-PIM) using the standard delayed enhancement (DE) acquisition in assessing viability following myocardial infarction (MI). SI-PIM quantifies MI density with a voxel-by-voxel resolution in clinically used DE images. In canines (n= 6), 96 hours after reperfused MI and administration of 0.2 mmol/kg Gd(DTPA), ex vivo DE images were acquired and SI-PIMs calculated. SI-PIM data were compared with data from DE images analyzed with several thresholding levels using SI(remote+2SD), SI(remote+6SD), SI full width half maximum (SI(FWHM)), and with triphenyl-tetrazolium-chloride (TTC) staining. SI-PIM was also compared to R1 percent infarct mapping (R1-PIM). Left ventricular infarct volumes (IV) in DE images, IV(SIremote+2SD) and IV(SIremote+6SD), overestimated (P < 0.05) TTC by medians of 13.21 mL [10.2; 15.2] and 6.2 mL [3.79; 8.23], respectively. SI(FWHM), SI-PIM, and R1-PIM, however, only nonsignificantly underestimated TTC, by medians of -0.10 mL [-0.12, -0.06], -0.86 mL [-1.04; 1.54], and -1.30 mL [-4.99; -0.29], respectively. The infarct-involved voxel volume (IIVV) of SI-PIM, 32.4 mL [21.2, 46.3] is higher (P < 0.01) than IIVVs of SI(FWHM) 8.3 mL [3.79, 19.0]. SI-PIM(FWHM), however, underestimates TTC (-5.74 mL [-11.89; -2.52] (P < 0.01)). Thus, SI-PIM outperforms SI(FWHM) because larger IIVVs are obtained, and thus PIs both in the rim and the core of the infarcted tissue are characterized, in contradistinction from DE-SI(FWHM), which shows mainly the infarct core. We have shown here, ex vivo, that SI-PIM has the same advantages as R1-PIM, but it is based on the scanning sequences of DE imaging, and thus it is obtainable within the same short scanning time as DE. This makes it a practical method for clinical studies.

Assessment of myocardial fibrosis by endoventricular electromechanical mapping in experimental nonischemic cardiomyopathy

Cardiac fibrosis plays an important prognostic role in nonischemic cardiomyopathy (NICM), making it a potential therapeutic target. Although electromechanical mapping has been used to identify myocardial scar and facilitate intramyocardial intervention in the setting of ischemic heart disease, its application has not been described in NICM. We assessed the detection of myocardial fibrosis by endoventricular electromechanical mapping in an experimental model of NICM. The NOGA® XP system was used to perform left ventricular mapping in twelve sheep that had undergone intracoronary doxorubicin dosing to induce NICM and in six healthy control animals. Results for endocardial voltage and mechanical shortening were evaluated against myocardial fibrosis burden, as determined by delayed-enhancement cardiac magnetic resonance and quantitative histomorphometry. Doxorubicin treatment resulted in dilated cardiomyopathy with moderate-severe impairment of left ventricular ejection fraction. Late gadolinium uptake was present in 9/12 doxorubicin animals, while histological fibrosis was approximately doubled compared to controls and was distributed multisegmentally throughout the left ventricle. Cardiomyopathy was associated with widespread reductions in unipolar and bipolar voltage amplitude and endocardial shortening. Each parameter showed an inverse relationship with the burden of fibrosis. Moreover, unipolar voltage and linear local shortening ratio displayed moderate accuracy for identifying myocardial segments with delayed contrast enhancement or increased fibrosis content, with optimal discriminatory thresholds of 7.5 mV and 11.5%, respectively. In this model of NICM, electromechanical mapping shows potential for delineating segmental differences in fibrosis. Pending clinical evaluation, it may therefore have applicability for directing targeted intramyocardial interventions in nonischemic heart disease.

Heterogeneous Microinfarcts Caused by Coronary Microemboli: Evaluation with Multidetector CT and MR Imaging in a Swine Model

To directly compare the sensitivity of 64-section multidetector computed tomography (CT) with that of 1.5-T magnetic resonance (MR) imaging in the depiction and measurement of heterogeneous 7-8-week-old microinfarcts and the quantification of regional left ventricular (LV) function and perfusion in the territory of coronary intervention in a swine model. Approval was obtained from the institutional animal committee. An x-ray/MR system was used to catheterize the left anterior descending (LAD) coronary artery with x-ray guidance and to delineate the perfusion territory. The vessel was selectively microembolized in six pigs with small-diameter embolic material (40-120 microm, 250000 count). At 7-8 weeks after microembolization, multidetector CT and MR imaging were used to assess LV function, first-pass perfusion, and delayed contrast enhancement in remote myocardium and microinfarct scars. Histochemical staining with triphenyltetrazolium chloride (TTC) was used to confirm and quantify heterogeneous microinfarct scars. The two-tailed Wilcoxon signed rank test was used to detect differences between modalities and myocardial regions. The LAD territory was 32.4% +/- 3.8(stadard error of the mean) of the LV mass. Multidetector CT and MR imaging have similar sensitivity in the detection of regional and global LV dysfunction and extent of microinfarct. The mean LV end-diastolic volume, end-systolic volume, and ejection fraction were 93 mL +/- 8, 46 mL +/- 4, and 50% +/- 3, respectively, on multidetector CT images and 92 mL +/- 8, 48 mL +/- 5, and 48% +/- 3, respectively, on MR images (P > or = .05). The extent of heterogeneous microinfarct was not significantly different between multidetector CT (6.3% +/- 0.8 of the LV mass), MR imaging (6.6% +/- 0.5 of the LV mass), and TTC staining (7.0% +/- 0.6 of the LV mass). First-pass multidetector CT and MR imaging demonstrated significant regional differences (P < .05) in time to peak between the heterogeneous microinfarct and remote myocardium (17.0 seconds +/- 0.3 and 12.4 seconds +/- 0.6, respectively, for multidetector CT and 17.2 seconds +/- 0.8 and 12.5 seconds +/- 1.0, respectively, for MR imaging). Modern multidetector CT and MR imaging are sensitive modalities with which to depict heterogeneous microinfarcts and determine regional LV dysfunction and decreased perfusion in the territory of intervention. (c) RSNA, 2010.