1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:431-439.

Background-In patients with acute myocardial infarction (MI), delayed enhancement is seen in MRI 5 to 7 minutes after gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection, and the enhancement occurs in regions that later show recovery of function. However, in a canine model of acute MI, delayed enhancement 20 to 30 minutes after injection only occurs in necrotic regions and not in surrounding, reversibly injured myocardium. The objective of the present study was to determine (1) if the size of the enhanced region varies with time after Gd-DTPA injection and (2) if and when the size of the enhanced region corresponds to the true infarct size. Methods and Results-The left coronary artery was occluded in 15 Lewis rats for 30 minutes (nϭ9) or 2 hours (nϭ6); this was followed by reperfusion. MRI scans were performed 48Ϯ2 hours after-MI. Midventricular short-axis images were obtained continuously for 40 minutes after Gd-DTPA injection (0.3 mmol/kg). The sizes of enhanced regions at each time were determined by threshold analysis and compared with triphenyltetrazolium chloride-stained sections of the excised rat heart. In all animals, the enhanced region overestimated infarct size (28Ϯ5%) immediately after the injection of Gd-DTPA, although it then gradually receded to match the size of the infarct. The time required for enhancement to accurately determine infarct size was significantly different between 2-hour infarcts (16Ϯ2 minutes) and 30-minute (26Ϯ4 minutes) infarcts (PϽ0.05). Conclusions-In reperfused acute MI, accurate determination of infarct size by delayed enhancement MRI requires imaging at specific times after Gd-DTPA injection, and this time varies with the duration of occlusion.

Background-Numerous criteria believed to define a positive response to cardiac resynchronization therapy have been used in the literature. No study has investigated agreement among these response criteria. We hypothesized that the agreement among the various response criteria would be poor. Methods and Results-A literature search was conducted with the keywords "cardiac resynchronization" and "response." The 50 publications with the most citations were reviewed. After the exclusion of editorials and reviews, 17 different primary response criteria were identified from 26 relevant articles. The agreement among 15 of these 17 response criteria was assessed in 426 patients from the Predictors of Response to Cardiac Resynchronization Therapy (PROSPECT) study with Cohen's -coefficient (2 response criteria were not calculable from PROSPECT data). The overall response rate ranged from 32% to 91% for the 15 response criteria. Ninety-nine percent of patients showed a positive response according to at least 1 of the 15 criteria, whereas 94% were classified as a nonresponder by at least 1 criterion.

Cardiovascular magnetic resonance (CMR) phase contrast imaging has undergone a wide range of changes with the development and availability of improved calibration procedures, visualization tools, and analysis methods. This article provides a comprehensive review of the current state-of-the-art in CMR phase contrast imaging methodology, clinical applications including summaries of past clinical performance, and emerging research and clinical applications that utilize today’s latest technology.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-015-0172-7) contains supplementary material, which is available to authorized users.