Akhlaque Uddin

MR Imaging of Cardiac Tumors and Masses: A Review of Methods and Clinical Applications

Cardiac masses are usually first detected at echocardiography. In their further evaluation, cardiac magnetic resonance (MR) imaging has become a highly valuable technique. MR imaging offers incremental value owing to its larger field of view, superior tissue contrast, versatility in image planes, and unique ability to enable discrimination of different tissue characteristics, such as water and fat content, which give rise to particular signal patterns with T1- and T2-weighted techniques. With contrast material-enhanced MR imaging, additional tissue properties such as vascularity and fibrosis can be demonstrated. MR imaging can therefore contribute to the diagnosis of a cardiac mass as well as be used to detail its relationship to other cardiac and extracardiac structures. These assessments are important to plan therapy, such as surgical intervention. In addition, serial MR studies can be used to monitor tumor regression after surgery or chemotherapy. Primary cardiac tumors are very rare; metastases and pseudotumors (eg, thrombus) are much more common. This article provides an overview of cardiac masses and reviews the optimal MR imaging techniques for their assessment.

Consequence of Cerebral Embolism After Transcatheter Aortic Valve Implantation Compared With Contemporary Surgical Aortic Valve Replacement Effect on Health-Related Quality of Life

Background—Incidence of cerebral microinfarcts is higher after transcatheter aortic valve implantation (TAVI) compared with surgical aortic valve replacement (SAVR). It is unknown whether these lesions persist and what direct impact they have on health-related quality of life. The objective was to identify predictors of cerebral microinfarction and measure their effect on health-related quality of life during 6 months after TAVI when compared with SAVR. Methods and Results—Cerebral MRI was conducted at baseline, post procedure, and 6 months using diffusion-weighted imaging. Health-related quality of life was measured at baseline, 30 days, and 6 months with short form-12 health outcomes and EuroQol 5 dimensions questionnaires. One hundred eleven patients (TAVI, n=71; SAVR, n=40) were studied. The incidence (54 [77%] versus 17 [43%]; P=0.001) and number (3.4±4.9 versus 1.2±1.8; P=0.001) of new microinfarcts were greater after TAVI than after SAVR. The total volume per microinfarct was smaller in TAVI than in SAVR (0.23±0.24 versus 0.76±1.8 mL; P=0.04). The strongest associations for microinfarction were: TAVI (arch atheroma grade: r=0.46; P=0.0001) and SAVR (concomitant coronary artery bypass grafting: r=−0.33; P=0.03). Physical component score in TAVI increased after 30 days (32.1±6.6 versus 38.9±7.0; P<0.0001) and 6 months (40.4±9.3; P<0.0001); the improvement occurred later in SAVR (baseline: 34.9±10.6; 30 days: 35.9±10.2; 6 months: 42.8±11.2; P<0.001). After TAVI, there were no differences in the short form-12 health outcome scores according to the presence or size of new cerebral infarction. Conclusions—Cerebral microinfarctions are more common after TAVI compared with SAVR but seem to have no negative effect on early (30 days) or medium term (6 months) health-related quality of life. Aortic atheroma (TAVI) and concomitant coronary artery bypass grafting (SAVR) are independent risk factors for cerebral microinfarction.

Rationale and design of the PRognostic Importance of MIcrovascular Dysfunction in asymptomatic patients with Aortic Stenosis (PRIMID-AS): a multicentre observational study with blinded investigations.

Introduction Aortic stenosis (AS) is the commonest valve disorder in the developed world requiring surgery. Surgery in patients with severe asymptomatic AS remains controversial. Exercise testing can identify asymptomatic patients at increased risk of death and symptom development, but with limited specificity, especially in older adults. Cardiac MRI (CMR), including myocardial perfusion reserve (MPR) may be a novel imaging biomarker in AS. Aims (1) To improve risk stratification in asymptomatic patients with AS and (2) to determine whether MPR is a better predictor of outcome than exercise testing and brain natriuretic peptide (BNP). Method/design Multicentre, prospective observational study in the UK, comparing MPR with exercise testing and BNP (with blinded CMR analysis) for predicting outcome. Population 170 asymptomatic patients with moderate-to-severe AS, who would be considered for aortic valve replacement (AVR). Primary outcome Composite of: typical symptoms necessitating referral for AVR and major adverse cardiovascular events. Follow-up: 12–30 months (minimum 12 months). Primary hypothesis MPR will be a better predictor of outcome than exercise testing and BNP. Ethics/dissemination The study has full ethical approval and is actively recruiting patients. Data collection will be completed in November 2014 and the study results will be submitted for publication within 6 months of completion. ClinicalTrials.gov identifier NCT01658345.

Sex-related differences in left ventricular remodeling in severe aortic stenosis and reverse remodeling after aortic valve replacement: A cardiovascular magnetic resonance study.

BACKGROUND Cardiac adaptation to aortic stenosis (AS) appears to differ according to sex, but reverse remodeling after aortic valve replacement has not been extensively described. The aim of the study was to determine using cardiac magnetic resonance imaging whether any sex-related differences exist in AS in terms of left ventricular (LV) remodeling, myocardial fibrosis, and reverse remodeling after valve replacement. METHODS One hundred patients (men, n = 60) with severe AS undergoing either transcatheter or surgical aortic valve replacement underwent cardiac magnetic resonance scans at baseline and 6 months after valve replacement. RESULTS Despite similar baseline comorbidity and severity of AS, women had a lower indexed LV mass than did men (65.3 ± 18.4 vs 81.5 ± 21.3 g/m(2), P < .001) and a smaller indexed LV end-diastolic volume (87.3 ± 17.5 vs 101.2 ± 28.6 mL/m(2), P = .002) with a similar LV ejection fraction (58.6% ± 10.2% vs 54.8% ± 12.9%, P = .178). Total myocardial fibrosis mass was similar between sexes (2.3 ± 4.1 vs 1.3 ± 1.1 g, P = .714), albeit with a differing distribution according to sex. After aortic valve replacement, men had more absolute LV mass regression than did women (18.3 ± 10.6 vs 12.7 ± 8.8 g/m(2), P = .007). When expressed as a percentage reduction of baseline indexed LV mass, mass regression was similar between the sexes (men 21.7% ± 10.1% vs women 18.4% ± 11.0%, P = .121). There was no sex-related difference in postprocedural LV ejection fraction or aortic regurgitation. Sex was not found to be a predictor of LV reverse remodeling on multiple regression analysis. CONCLUSIONS There are significant differences in the way that male and female hearts adapt to AS. Six months after aortic valve replacement, there are no sex-related differences in reverse remodeling, but superior reverse remodeling in men as a result of their more adverse remodeling profile at baseline.

Myocardial Extracellular Volume Estimation by CMR Predicts Functional Recovery Following Acute MI

Objectives In the setting of reperfused acute myocardial infarction (AMI), the authors sought to compare prediction of contractile recovery by infarct extracellular volume (ECV), as measured by T1-mapping cardiac magnetic resonance (CMR), with late gadolinium enhancement (LGE) transmural extent. Background The transmural extent of myocardial infarction as assessed by LGE CMR is a strong predictor of functional recovery, but accuracy of the technique may be reduced in AMI. ECV mapping by CMR can provide a continuous measure associated with the severity of tissue damage within infarcted myocardium. Methods Thirty-nine patients underwent acute (day 2) and convalescent (3 months) CMR scans following AMI. Cine imaging, tissue tagging, T2-weighted imaging, modified Look-Locker inversion T1 mapping natively and 15 min post–gadolinium-contrast administration, and LGE imaging were performed. The ability of acute infarct ECV and acute transmural extent of LGE to predict convalescent wall motion, ejection fraction (EF), and strain were compared per-segment and per-patient. Results Per-segment, acute ECV and LGE transmural extent were associated with convalescent wall motion score (p < 0.01; p < 0.01, respectively). ECV had higher accuracy than LGE extent to predict improved wall motion (area under receiver-operating characteristics curve 0.77 vs. 0.66; p = 0.02). Infarct ECV ≤0.5 had sensitivity 81% and specificity 65% for prediction of improvement in segmental function; LGE transmural extent ≤0.5 had sensitivity 61% and specificity 71%. Per-patient, ECV and LGE correlated with convalescent wall motion score (r = 0.45; p < 0.01; r = 0.41; p = 0.02, respectively) and convalescent EF (p < 0.01; p = 0.04). ECV and LGE extent were not significantly correlated (r = 0.34; p = 0.07). In multivariable linear regression analysis, acute infarct ECV was independently associated with convalescent infarct strain and EF (p = 0.03; p = 0.04), whereas LGE was not (p = 0.29; p = 0.24). Conclusions Acute infarct ECV in reperfused AMI can complement LGE assessment as an additional predictor of regional and global LV functional recovery that is independent of transmural extent of infarction.

Cardiac remodelling and function with primary mitral valve insufficiency studied by magnetic resonance imaging

AIMS Evaluation of patients with primary mitral valve insufficiency (MI) is best supported by quantitative measures. Cardiovascular magnetic resonance imaging (CMR) offers flow and cardiac chamber volume quantification. We studied cardiac remodelling with CMR to determine MI regurgitation volumes (MIVol) related to severe MI. METHODS AND RESULTS In total, 24, 20, and 28 patients determined to have mild, moderate, and severe primary MI, respectively, were studied. Combining cine stacks with phase-contrast velocity mapping across the ascending aorta, CMR-determined MIVol was reproducibly obtained as the difference between left ventricular (LV) stroke volume and aortic forward flow (Aoflow). With increasing MI severity, MIVol, left heart volumes, and pulmonary venous diameters increased (P < 0.01). Severe MI with LV end-systolic diameter of 40 mm was signified by MIVol >40 mL, MI regurgitant fraction >0.30, LV end-diastolic volume (LVEDV(i)) >108 mL m(-2), and a total left heart volume >188 mL m(-2) with dilated pulmonary veins and a LVEDV/right ventricular EDV ratio >1.2. In severe MI, LV ejection fraction was unaffected, but the Aoflow and the peak ejection rate indexed to LVEDV were lowered (P < 0.05). In surgical patients, the MIVol correlated to the decrease in LV dimension after valve surgery (P < 0.02). CONCLUSION CMR provides a reproducible quantitative technique for evaluation of MI, as MIVol and cardiac chamber volumes can be held against diagnostic cut-off values. The Aoflow and peak ejection rate indexed to LVEDV may reveal early LV systolic dysfunction in patients with severe MI. Severe MI is related to lower MI regurgitation volume and fraction than previously believed.

Reciprocal ECG change in reperfused ST-elevation myocardial infarction is associated with myocardial salvage and area at risk assessed by cardiovascular magnetic resonance

Objective ST-elevation acute myocardial infarction (STEMI) is frequently associated with reciprocal ST depression in contralateral ECG leads. The relevance of these changes is debated. This study examined whether reciprocal ECG changes in STEMI reflect larger myocardial area at risk (AAR) and/or infarct size. Design Patients were stratified by presence of reciprocal change on the presenting ECG, defined as ≥1 mm ST depression in ≥2 inferior leads for anterior STEMI, or ≥2 anterior leads for inferior STEMI. Infarcted tissue was defined on late enhancement and AAR on T2-weighted cardiovascular magnetic resonance (CMR). Setting Patients with reperfused first STEMI underwent CMR within 3 days of presentation. Main outcome measures In addition to AAR and infarct mass, myocardial salvage was calculated as (AAR mass—infarct mass) and salvage index as myocardial salvage/AAR mass. Results Thirty-five patients were analysed (n=35). Patients with reciprocal ECG changes (n=19) had higher AAR mass than those without (42 g vs 29 g, p<0.001), and higher myocardial salvage (27 g vs 9 g, p<0.001) and myocardial salvage index (61% vs 17%, p<0.001) but similar infarct size (16 g vs 20 g, p=0.3) and ejection fraction (43% vs 45%, p=0.5). Conclusions STEMI patients with reciprocal ECG changes have larger AAR, higher myocardial salvage and salvage index than those without. Reciprocal changes appear to be a marker of increased ischaemic myocardium at risk and indicate the potential for increased salvage with emergency revascularisation. Reciprocal changes showed no relationship to infarct size, which may be influenced by ischaemia time and other treatment factors.

Quantification of myocardial blood flow with cardiovascular magnetic resonance throughout the cardiac cycle.

BackgroundMyocardial blood flow (MBF) varies throughout the cardiac cycle in response to phasic changes in myocardial tension. The aim of this study was to determine if quantitative myocardial perfusion imaging with cardiovascular magnetic resonance (CMR) can accurately track physiological variations in MBF throughout the cardiac cycle.Methods30 healthy volunteers underwent a single stress/rest perfusion CMR study with data acquisition at 5 different time points in the cardiac cycle (early-systole, mid-systole, end-systole, early-diastole and end-diastole). MBF was estimated on a per-subject basis by Fermi-constrained deconvolution. Interval variations in MBF between successive time points were expressed as percentage change. Maximal cyclic variation (MCV) was calculated as the percentage difference between maximum and minimum MBF values in a cardiac cycle.ResultsAt stress, there was significant variation in MBF across the cardiac cycle with successive reductions in MBF from end-diastole to early-, mid- and end-systole, and an increase from early- to end-diastole (end-diastole: 4.50 ± 0.91 vs. early-systole: 4.03 ± 0.76 vs. mid-systole: 3.68 ± 0.67 vs. end-systole 3.31 ± 0.70 vs. early-diastole: 4.11 ± 0.83 ml/g/min; all p values <0.0001). In all cases, the maximum and minimum stress MBF values occurred at end-diastole and end-systole respectively (mean MCV = 26 ± 5%). There was a strong negative correlation between MCV and peak heart rate at stress (r = −0.88, p < 0.001). The largest interval variation in stress MBF occurred between end-systole and early-diastole (24 ± 9% increase). At rest, there was no significant cyclic variation in MBF (end-diastole: 1.24 ± 0.19 vs. early-systole: 1.28 ± 0.17 vs.mid-systole: 1.28 ± 0.17 vs. end-systole: 1.27 ± 0.19 vs. early-diastole: 1.29 ± 0.19 ml/g/min; p = 0.71).ConclusionQuantitative perfusion CMR can be used to non-invasively assess cyclic variations in MBF throughout the cardiac cycle. In this study, estimates of stress MBF followed the expected physiological trend, peaking at end-diastole and falling steadily through to end-systole. This technique may be useful in future pathophysiological studies of coronary blood flow and microvascular function.

Difference between cerebral embolic events following Transcatheter Aortic Valve Implantation (TAVI) and Surgical Aortic Valve Replacement (SAVR): a diffusion weighted MRI study

Background Transcatheter Aortic Valve Implantation (TAVI) is used to treat symptomatic severe aortic stenosis in a non-surgical high risk population. The incidence of stroke and micro-infarction is higher in the TAVI population compared to surgical aortic valve replacement (SAVR) at 30 days, which may be due to various factors such as valve calcification and aortic atheroma. However, the natural history and clinical consequences of micro-infarction is unknown.

Associated factors for a false negative cardiovascular magnetic resonance perfusion study: a CE-MARC substudy

Background Diagnosis of coronary ischemia by perfusion CMR has high sensitivity and specificity when using X-ray coronary angiography as the reference standard. A variety of possible reasons have been given for false negative perfusion CMR studies, such as suboptimal image quality, technical reasons, or the potential discrepancy between angiographic stenosis and detectable myocardial hypoperfusion. The rates at which these factors occur have not been specifically studied to date. The CE-MARC study prospectively enrolled 752 patients with suspected coronary artery disease, scheduled to undergo CMR, SPECT and X-ray coronary angiography [1]. We assessed potential reasons for the false negative CMR perfusion studies within CE-MARC.