Background T2-weighted cardiac magnetic resonance (CMR) is useful in diagnosing acute inflammatory myocardial diseases such as myocarditis and tako-tsubo cardiomyopathy (TTCM). We hypothesized that quantitative T2 mapping could better delineate myocardial involvement in these disorders vs. T2-weighted imaging. Methods and Results Thirty patients with suspected myocarditis or TTCM referred for CMR who met established diagnostic criteria underwent myocardial T2 mapping. T2 values were averaged in involved and remote myocardial segments, both defined by a reviewer blinded to T2 data. In myocarditis, T2 was 65.2±3.2ms in the involved myocardium vs. 53.5±2.1 in remote myocardium (p<0.001). In TTCM, T2 was 65.6±4.0ms in the involved myocardium vs. 53.6±2.7ms in remote segments (p<0.001). T2 values were similar across remote myocardial segments in patients and all myocardial segments in controls (p>0.05 for all). T2 maps provided diagnostic data even in patients with difficulty breath-holding. A T2 cutoff of 59ms identified areas of myocardial involvement with sensitivity and specificity of 94% and 97%, respectively. T2 mapping revealed regions of abnormal T2 beyond those identified by wall motion abnormalities or LGE-positivity. Conventional T2-weighted short tau inversion recovery (T2W-STIR) images were uninterpretable in 7 patients due to artifact and unremarkable in 2 who had elevated T2 values. T2-prepared steady state free precession (T2p-SSFP) images showed areas of signal hyperintensity in only17/30 patients. Conclusions Quantitative T2 mapping reliably identifies myocardial involvement in patients with myocarditis and TTCM. T2 mapping delineated greater extent of myocardial disease in both conditions compared to that identified by wall motion abnormalities, T2W-STIR, T2p-SSFP or LGE. Quantitative T2 mapping warrants consideration as a robust technique to identify myocardial injury in patients with acute myocarditis or TTCM.

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OBJECTIVES The purpose of this study was to evaluate the ability of a novel cardiac magnetic resonance (CMR) real-time phase contrast (RT-PC) flow measurement technique to reveal the discordant respirophasic changes in mitral and tricuspid valve in flow indicative of the abnormal hemodynamics seen in constrictive pericarditis (CP). BACKGROUND Definitive diagnosis of CP requires identification of constrictive hemodynamics with or without pericardial thickening. CMR to date has primarily provided morphological assessment of the pericardium. METHODS Sixteen patients (age 57 ± 13 years) undergoing CMR to assess known or suspected CP and 10 controls underwent RT-PC that acquired simultaneous mitral valve and tricuspid valve inflow velocities over 10 s of unrestricted breathing. The diagnosis of CP was confirmed via clinical history, diagnostic imaging, cardiac catheterization, intraoperative findings, and histopathology. RESULTS Ten patients had CP, all with increased pericardial thickness (6.2 ± 1.0 mm). RT-PC imaging demonstrated discordant respirophasic changes in atrioventricular valve inflow velocities in all CP patients, with mean ± SD mitral valve and tricuspid valve inflow velocity variation of 46 ± 20% and 60 ± 15%, respectively, compared with 16 ± 8% and 24 ± 11% in patients without CP (p < 0.004 vs. patients with CP for both) and 17 ± 5% and 31 ± 13% in controls (p < 0.001 vs. patients with CP for both). There was no difference in atrioventricular valve inflow velocity variation between patients without CP compared with controls (p > 0.3 for both). Respiratory variation exceeding 25% across the mitral valve yielded a sensitivity of 100%, a specificity of 100%, and an area under the receiver-operating characteristic curve of 1.0 to detect CP physiology. Using a cutoff of 45%, variation of transtricuspid valve velocity had a sensitivity of 90%, a specificity of 88%, and an area under the receiver-operating characteristic curve of 0.98. CONCLUSIONS Accentuated and discordant respirophasic changes in mitral valve and tricuspid valve inflow velocities characteristic of CP can be identified noninvasively with RT-PC CMR. When incorporated into existing CMR protocols for imaging pericardial morphology, RT-PC CMR provides important hemodynamic evidence with which to make a definite diagnosis of CP.

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Acute coronary syndromes (ACS) continue to be the most common morbid condition of industrialized nations. The advent of and technical improvements in revascularization and medical therapy have led to a steady decline in mortality rates. However, many patients who suffer unstable angina or myocardial infarction require further testing and risk stratification to guide therapeutic selection and prognosis assignment. Myocardial edema imaging with cardiac magnetic resonance (CMR) affords the ability to define the amount of myocardium at risk, refine estimates of prognosis and provide guidance for therapies with excellent sensitivity compared to standard clinical markers. This review will discuss the rationale for edema imaging, how it is performed using CMR and its potential clinical applications.