D. D. Lubbers

Reduced regional myocardial perfusion reserve is associated with impaired contractile performance in idiopathic dilated cardiomyopathy

Background. In idiopathic dilated cardiomyopathy (IDC) an imbalance between myocardial oxygen consumption and supply has been postulated. Subclinical myocardial ischaemia may contribute to progressive deterioration of left ventricular function. The relation between regional myocardial perfusion reserve (MPR) and contractile performance was investigated.Methods. Patients with newly diagnosed IDC underwent positron emission tomography (PET) scanning using both 13N-ammonia as a perfusion tracer (baseline and dypiridamole stress), and 18F-fluorodeoxyglucose viability tracer and a dobutamine stress MRI. MPR (assessed by PET) as well as wall motion score (WMS, assessed by MRI) were evaluated in a 17-segment model.Results. Twenty-two patients were included (age 49±11 years; 15 males, LVEF 33±10%). With MRI, a total of 305 segments could be analysed. Wall motion abnormalities at rest were present in 127 (35.5%) segments and in 103 (29.9%) during dobutamine stress. Twenty-one segments deteriorated during stress and 43 improved. MPR was significantly higher in those segments that improved, compared with those that did not change or were impaired during stress (1.87±0.04 vs. 1.56± 0.07 p<0.01.)Conclusion. Signs of regional ischaemia were clearly present in IDC patients. Ischaemic regions displayed impaired contractility during stress. This suggests that impaired oxygen supply contributes to cardiac dysfunction in IDC. (Neth Heart J 2009;17:470–4.)

Semi-automatic measurement of left ventricular function on dual source computed tomography using five different software tools in comparison with magnetic resonance imaging

PURPOSE To compare left ventricular (LV) function assessment using five different software tools on the same dual source computed tomography (DSCT) datasets with the results of MRI. MATERIALS AND METHODS Twenty-six patients, undergoing cardiac contrast-enhanced DSCT were included (20 men, mean age 59±12 years). Reconstructions were made at every 10% of the RR-interval. Function analysis was performed with five different, commercially available workstations. In all software tools, semi-automatic LV function measurements were performed, with manual corrections if necessary. Within 0-22 days, all 26 patients were scanned on a 1.5 T MRI-system. Bland-Altman analysis was performed to calculate limits of agreement between DSCT and MRI. Pearsons correlation coefficient was calculated to assess the correlation between the different DSCT software tools and MRI. Repeated measurements were performed to determine intraobserver and interobserver variability. RESULTS For all five DSCT workstations, mean LV functional parameters correlated well with measurements on MRI. Bland-Altman analysis of the comparison of DSCT and MRI showed acceptable limits of agreement. Best correlation and limits of agreement were obtained by DSCT software tools with software algorithms comparable to MRI software. CONCLUSION The five different DSCT software tools we examined have interchangeable results of LV functional parameters compared to regularly analysed results by MRI. The best correlation and the narrowest limits of agreement were found when the same software algorithm was used for both DSCT and MRI examinations, therefore our advice for clinical practice is to always evaluate images with the same type of post-processing tools in follow-up.

Assessment of global left ventricular functional parameters: analysis of every second short-axis Magnetic Resonance Imaging slices is as accurate as analysis of consecutive slices

The purpose of this study was to assess whether accurate global left-ventricular (LV) functional parameters can be obtained by analyzing every second short-axis magnetic resonance imaging cine series instead of consecutive slices, in order to reduce post-processing time. Forty patients, were scanned on a 1.5 T MRI-system (Magnetom Sonata, Siemens Medical Systems, Erlangen, Germany) using a steady-state free precession (SSFP) sequence. A stack of short-axis cine series from above the mitral valve through the apex was acquired. Post-processing was started at the most basal slice of the left ventricle, in which at least 50% of the circumference was myocardium. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and LV mass (LVM), were calculated. Data analysis was repeated, but now only every second slice was analyzed. Bland–Altman analysis showed slightly lower values for all LV parameters when only every second slice was analyzed, ranging from 1.7% difference for EF (limits of agreement −3.5 to 5.0) to 4.6% for SV (limits of agreement −7.2 to 15.0). Analysis of every second slice for quantification of global LV function is time-saving and as accurate as analysis of consecutive slices.

Influence of the Choice of Software Package on the Outcome of Semiquantitative MR Myocardial Perfusion Analysis

PURPOSE To assess the repeatability and reproducibility of semiquantitative magnetic resonance (MR) perfusion analysis performed by using different software packages. MATERIALS AND METHODS The study protocol was approved by the institutional ethics committee. Informed consent was obtained from each patient. Semiquantitative perfusion analysis was performed twice by two independent observers using four dedicated software packages. MR perfusion datasets originated from eight patients with known single-vessel disease who were scheduled for percutaneous coronary intervention (PCI) on the basis of coronary angiography findings. Each patient underwent two examinations: 1 day before and 1 day after PCI. Repeatability (intra- and interobserver agreements) and reproducibility (intersoftware agreement) were evaluated for perfusion upslope and myocardial perfusion reserve index with Student t test and Bland-Altman analyses. RESULTS Intra- and interobserver agreements were good and comparable for repeated measurements within each individual software platform (mean differences < 6%, intraclass correlation coefficient [ICC] ≥ 0.68). However, the intersoftware variability was significant (limits of agreement ≥ 65%, ICC ≤ 0.67) such that the values produced with the different software packages are not interchangeable. CONCLUSION The results indicate high repeatability within individual software but low reproducibility between different software packages, suggesting that within-group and/or sequential observation of semiquantitative perfusion parameters must be performed with the same software platform. Before semiquantitative perfusion analysis can be incorporated reliably into clinical studies, it is important to resolve the differences between the software packages.

Why are We Interested in Viability

The number of patients with left ventricular (LV) dysfunction due to coronary artery disease is increasing, as more patients now survive with acute myocardial infarction (MI) through primary reperfusion therapy. Severe LV dysfunction after MI, especially in combination with heart failure, is associated with a poor prognosis. Differentiation between reversible and irreversible LV dysfunction is important, as in the first situation, surgical revascularization improves prognosis. In case of reversible LV dysfunction, the myocardium can be stunned or hibernating. These principles are described. Myocardial viability assessment by noninvasive imaging techniques are indicated for this purpose. The different established imaging modalities for myocardial viability assessment are discussed in this chapter.