Magnetic Resonance for Differential Diagnosis of Left Ventricular Hypertrophy: Diagnostic and Prognostic Implications.

BACKGROUND: Left ventricular hypertrophy (LVH) may be due to different causes, ranging from benign secondary forms to severe cardiomyopathies. Transthoracic Echocardiography (TTE) and ECG are the first-level examinations for LVH diagnosis. Cardiac magnetic resonance (CMR) accurately defines LVH type, extent and severity. OBJECTIVES: to evaluate the diagnostic and prognostic role of CMR in patients with TTE and/or ECG evidence of LVH. METHODS: We performed CMR in 300 consecutive patients with echocardiographic and/or ECG signs of LVH. RESULTS: Overall, 275 patients had TTE evidence of LVH, with initial suspicion of hypertrophic cardiomyopathy (HCM) in 132 (44%), cardiac amyloidosis in 41 (14%), hypertensive LVH in 48 (16%), aortic stenosis in 4 (1%), and undetermined LVH in 50 (16%). The initial echocardiographic diagnostic suspicion of LVH was confirmed in 172 patients (57.3%) and changed in 128 patients (42.7%, p < 0.0001): the diagnosis of HCM increased from 44% to 71% of patients; hypertensive and undetermined LVH decreased significantly (respectively to 4% and 5%). CMR allowed for a diagnosis in 41 out of 50 (82%) patients with undetermined LVH at TTE. CMR also identified HCM in 17 out of 25 patients with apparently normal echocardiography but with ECG criteria for LVH. Finally, the reclassification of the diagnosis by CMR was associated with a change in survival risk of patients: after CMR reclassification, no events occurred in patients with undetermined or hypertensive LVH. CONCLUSIONS: CMR changed echocardiographic suspicion in almost half of patients with LVH. In the subgroup of patients with abnormal ECG, CMR identified LVH (particularly HCM) in 80% of patients. This study highlights the indication of CMR to better characterize the type, extent and severity of LVH detected at echocardiography and suspected with ECG.

Myocardial T1 Values at 1.5 T: Normal Values for General Electric Scanners and Sex-Related Differences.

BACKGROUND: No data are available about normal ranges for native T1 in human myocardium using General Electric (GE) scanners. PURPOSE: To establish normal ranges for myocardial T1 values and evaluate regional variability and the influence of physiological factors. STUDY TYPE: Prospective. SUBJECTS: One hundred healthy volunteers with normal electrocardiogram, no cardiovascular/systemic diseases, or risk factors (age range: 20-70 years; 50 females). FIELD STRENGTH/SEQUENCE: 1.5 T/Steady-state free precession cine and a modified Look-Locker inversion recovery sequence in diastole (also in systole for 61 volunteers). ASSESSMENT: Image analysis was performed by operators with >10 years experience in cardiac MR using commercially available software. T1 values were calculated for 16 myocardial segments, and the global value was the mean. Segments were grouped according to circumferential region (anterior, septal, inferior, and lateral) and to level (basal, medial, apical). Twenty images were analyzed twice by the same operator and by a different operator to assess reproducibility. STATISTICAL TESTS: Independent-samples t-test or Mann-Whitney test; paired sample t-test or Wilcoxon signed-rank test; one-way repeated measures ANOVA or Friedman tests; Pearson's or Spearman's correlation. Reproducibility evaluated using coefficient of variability (CoV). RESULTS: Due to artifacts and/or partial-volume effects, 45/1600 (2.8%) segments were excluded. A good intra- and inter-operator reproducibility was detected (CoV < 5%). There were significant differences in segmental T1 values (P < 0.05). A significant circumferential variability was present (P < 0.05): the mean native T1 value over the lateral region was significantly lower than in the other three regions. An increasing gradient from basal to apical slices was detected (P < 0.05). Segmental and global T1 values were not associated with age (range P = 0.052-0.911) but were significantly lower in males than in females (global: 993 ± 32 vs. 1037 ± 27 ms; P < 0.05) and significantly correlated with heart rate (range R for segmental values = 0.247-0.920; P < 0.05). Almost all segmental T1 values were inversely correlated with wall thickness (R from -0.233 to -0.514; P < 0.05). Systolic T1 values were significantly lower than diastolic values in basal anteroseptal segment, in all medial segments except the inferior one, and in all apical segments (P < 0.05). DATA CONCLUSION: Myocardial T1 values differ among myocardial regions, are influenced by sex, heart rate, and wall thickness and vary according to the cardiac cycle in healthy adults. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Biventricular Reference Values by Body Surface Area, Age, and Gender in a Large Cohort of Well-Treated Thalassemia Major Patients Without Heart Damage Using a Multiparametric CMR Approach.

BACKGROUND: Cardiac MRI plays a critical role in the management of thalassemic patients. No accurate biventricular reference values are available. PURPOSE: To establish the ranges for normal left ventricular (LV) and right ventricular (RV) volumes and ejection fraction (EF) and LV mass normalized to body surface area (BSA), age, and gender in a large cohort of well-treated beta-thalassemia major (ß-TM) patients without heart damage using a multiparametric MRI. STUDY TYPE: Retrospective/cohort study. POPULATION: In all, 251 ß-TM patients with no known risk factors or cardiac disease, normal electrocardiogram, no macroscopic myocardial fibrosis, and all cardiac segments with T2 * ≥20 msec, and 246 healthy subjects. FIELD STRENGTH/SEQUENCE: 1.5T/cine steady-state free precession (SSFP), gradient-echo T2 *, late gadolinium enhancement (LGE) images. ASSESSMENT: Biventricular end-diastolic volume, end-systolic volume, stroke volume, and LV mass were normalized to BSA (EDVI, ESVI, SVI). STATISTICAL TESTS: Comparisons between the two groups was performed with two-samples t-test or Wilcoxon's signed rank test. For more than two groups, one-way analysis of variance (ANOVA) or a Kruskal-Wallis test were applied. RESULTS: Compared to controls, males with ß-TM showed significantlt higher LVEDVI in all the age groups, while for the other volumes the difference was significant only within one or more age groups. In females the volumes were comparable between ß-TM patients and healthy subjects in all the age groups. In the male ß-TM population we found a significant effect of age on LVEDVI (P = 0.017), LVESVI (P = 0.001), RVESVI (P = 0.029), and RVEF (P = 0.031), while for females none of the biventricular parameters were significantly different among the age groups (LVEDVI: P = 0.614; LVESVI: P = 0.449; LVSVI: P = 0.186; LV mass index: P = 0.071; LVEF: P = 0.059; RVEDVI: P = 0.374; RVESVI: P = 0.180; RVSVI: P = 0.206; RVEF: P = 0.057). In ß-TM patients all biventricular volume indexes as well as the LV mass index were significantly larger in males than in females (P < 0.0001 in all cases). The LV and the RV EF were comparable between the sexes (P = 0.568 and P = 0.268, respectively). DATA CONCLUSION: Appropriate "normal" reference ranges normalized to BSA, sex, and age are recommended to avoid misdiagnosis of cardiomyopathy in ß-TM patients. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 2.