BackgroundTo compare 11 heartbeat (HB) and 17 HB modified lock locker inversion recovery (MOLLI) pulse sequence at 3T and to establish preliminary reference values for myocardial T1 and the extracellular volume fraction (ECV).MethodsBoth phantoms and normal volunteers were scanned at 3T using 11 HB and 17 HB MOLLI sequence with the following parameters: spatial resolution = 1.75 × 1.75 × 10 mm on a 256 × 180 matrix, TI initial = 110 ms, TI increment = 80 ms, flip angle = 35°, TR/TE = 1.9/1.0 ms. All volunteers were administered Gadolinium-DTPA (Magnevist, 0.15 mmol/kg), and multiple post-contrast MOLLI scans were performed at the same pre-contrast position from 3.5-23.5 minutes after a bolus contrast injection. Late gadolinium enhancement (LGE) images were also acquired 12-30 minutes after the gadolinium bolus.ResultsT1 values of 11 HB and 17 HB MOLLI displayed good agreement in both phantom and volunteers. The average pre-contrast myocardial and blood T1 was 1315 ± 39 ms and 2020 ± 129 ms, respectively. ECV was stable between 8.5 to 23.5 minutes post contrast with an average of 26.7 ± 1.0%.ConclusionThe 11 HB MOLLI is a faster method for high-resolution myocardial T1 mapping at 3T. ECV fractions are stable over a wide time range after contrast administration.

BackgroundMyocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in the presence of myocardial fibrosis. The purpose of this study was to evaluate acquisition factors that may result in variation of measured T1 time and ECV including magnetic field strength, cardiac phase and myocardial region.Methods31 study subjects were enrolled and underwent one cardiovascular MR exam at 1.5 T and two exams at 3 T, each on separate days. A Modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired before and 5, 10, 12, 20, 25 and 30 min after administration of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist) at 1.5 T (exam 1). For exam 2, MOLLI sequences were acquired at 3 T both during diastole and systole, before and after administration of Gd-DTPA (0.15 mmol/kg Magnevist).Exam 3 was identical to exam 2 except gadobenate dimeglumine was administered (Gd-BOPTA; 0.1 mmol/kg Multihance). T1 times were measured in myocardium and blood. ECV was calculated by (ΔR1myocardium/ΔR1blood)*(1-hematocrit).ResultsBefore gadolinium, T1 times of myocardium and blood were significantly greater at 3 T versus 1.5 T (28% and 31% greater, respectively, p < 0.001); after gadolinium, 3 T values remained greater than those at 1.5 T (14% and 12% greater for myocardium and blood at 3 T with Gd-DTPA, respectively, p < 0.0001 and 18% and 15% greater at 3 T with Gd-BOPTA, respectively, p < 0.0001). However, ECV did not vary significantly with field strength when using the same contrast agent at equimolar dose (p = 0.2). Myocardial T1 time was 1% shorter at systole compared to diastole pre-contrast and 2% shorter at diastole compared to systole post-contrast (p < 0.01). ECV values were greater during diastole compared to systole on average by 0.01 (p < 0.01 to p < 0.0001). ECV was significantly higher for the septum compared to the non-septal myocardium for all three exams (p < 0.0001-0.01) with mean absolute differences of 0.01, 0.004, and 0.07, respectively, for exams 1, 2 and 3.ConclusionECV is similar at field strengths of 1.5 T and 3 T. Due to minor variations in T1 time and ECV during the cardiac cycle and in different myocardial regions, T1 measurements should be obtained at the same cardiac phase and myocardial region in order to obtain consistent results.

Background A high degree of non-compacted (trabeculated) myocardium in relationship to compact myocardium (T/M ratio >2.3) has been associated with a diagnosis of left ventricular non-compaction (LVNC). The purpose of this study was to determine the normal range of the T/M ratio in a large population-based study and to examine the relationship to demographic and clinical parameters. Methods and Results The thickness of trabeculation and the compact myocardium were measured in eight LV regions on long axis cardiac magnetic resonance (CMR) steady-state free precession cine images in 1000 participants (551 women; 68.1±8.9 years) of the Multi-Ethnic Study of Atherosclerosis cohort. Of 323 participants without cardiac disease or hypertension and with all regions evaluable 140 (43%) had a T/M ratio >2.3 in at least one region; in 20/323 (6%), T/M>2.3 was present in more than two regions. Multivariable linear regression model revealed no association of age, gender, ethnicity, height and weight with maximum T/M ratio in participants without cardiac disease or hypertension (p>0.05). In the entire cohort (n=1000) LVEF (β=−0.02/%; p=0.015), LVEDV (β=0.01/ml; p=<0.0001) and LVESV (β=0.01/ml; p<0.001) were associated with maximum T/M ratio in adjusted models while there was no association with hypertension or myocardial infarction (p>0.05). At the apical level T/M ratios were significantly lower when obtained on short- compared to long-axis images (p=0.017). Conclusions A ratio of trabeculated to compact myocardium of more than 2.3 is common in a large population based cohort. These results suggest reevaluation of the current CMR criteria for LVNC may be necessary.

Purpose:To develop a cardiac computed tomographic (CT) method with which to determine extracellular volume (ECV) fraction, with cardiac magnetic resonance (MR) imaging as the reference standard. Materials and Methods:Study participants provided written informed consent to participate in this institutional review board-approved study. ECV was measured in healthy subjects and patients with heart failure by using cardiac CT and cardiac MR imaging. Paired Student t test, linear regression analysis, and Pearson correlation analysis were used to determine the relationship between cardiac CT and MR imaging ECV values and clinical parameters. Results:Twenty-four subjects were studied. There was good correlation between myocardial ECV measured at cardiac MR imaging and that measured at cardiac CT (r = 0.82, P , .001). As expected, ECV was higher in patients with heart failure than in healthy control subjects for both cardiac CT and cardiac MR imaging (P = .03, respectively). For both cardiac MR imaging and cardiac CT, ECV was positively associated with end diastolic and end systolic volume and inversely related to ejection fraction (P , .05 for all). Mean radiation dose was 1.98 mSv 6 0.16 (standard deviation) for each cardiac CT acquisition. Conclusion:ECV at cardiac CT and that at cardiac MR imaging showed good correlation, suggesting the potential for myocardial tissue characterization with cardiac CT.q RSNA, 2012

EWB patients tolerated earlier full weightbearing compared with 6WC patients, and there were no disadvantages with EWB compared with 6WC concerning hospital stay, pain intensities, time until return to work, and Olerud/Tegner Scores. Potential candidates for EWB are patients with a stable osteosynthesis of their fractured ankles as judged by the responsible surgeon, compliance, and high motivation.

PurposeMyocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in patients with diffuse myocardial fibrosis. The purpose of this study was to perform an intra-individual assessment of normal T1 time and ECV for two different contrast agents.MethodsA modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired at 3 T in 24 healthy subjects (8 men; 28 ± 6 years) at mid-ventricular short axis pre-contrast and every 5 min between 5-45 min after injection of a bolus of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist®) (exam 1) and 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA; Multihance®) (exam 2) during two separate scanning sessions. T1 times were measured in myocardium and blood on generated T1 maps. ECVs were calculated as ΔR1myocardium/ΔR1blood*1−hematocrit.ResultsMean pre-contrast T1 relaxation times for myocardium and blood were similar for both the first and second CMR exam (p > 0.5). Overall mean post-contrast myocardial T1 time was 15 ± 2 ms (2.5 ± 0.7%) shorter for Gd-DTPA at 0.15 mmol/kg compared to Gd-BOPTA at 0.1 mmol/kg (p < 0.01) while there was no significant difference for T1 time of blood pool (p > 0.05). Between 5 and 45 minutes after contrast injection, mean ECV values increased linearly with time for both contrast agents from 0.27 ± 0.03 to 0.30 ± 0.03 (p < 0.0001). Mean ECV values were slightly higher (by 0.01, p < 0.05) for Gd-DTPA compared to Gd-BOPTA. Inter-individual variation of ECV was higher (CV 8.7% [exam 1, Gd-DTPA] and 9.4% [exam 2, Gd-BOPTA], respectively) compared to variation of pre-contrast myocardial T1 relaxation time (CV 4.5% [exam 1] and 3.0% [exam 2], respectively). ECV with Gd-DTPA was highly correlated to ECV by Gd-BOPTA (r = 0.803; p < 0.0001).ConclusionIn comparison to pre-contrast myocardial T1 relaxation time, variation in ECV values of normal subjects is larger. However, absolute differences in ECV between Gd-DTPA and Gd-BOPTA were small and rank correlation was high. There is a small and linear increase in ECV over time, therefore ideally images should be acquired at the same delay after contrast injection.

Background Increased left ventricular myocardial thickness (LVMT) is a feature of several cardiac diseases. The purpose of this study was to establish standard reference values of normal LVMT with cardiac MR (CMR) and to assess variation with image acquisition plane, demographics and LV function. Methods and Results End-diastolic LVMT was measured on CMR steady-state free precession cine long and short axis images in 300 consecutive participants free of cardiac disease (169 women; 65.6±8.5 years) of the Multi-Ethnic Study of Atherosclerosis cohort. Mean LVMT on short axis images at the mid-cavity level was 5.3±0.9mm and 6.3±1.1mm for women and men, respectively. The average of the maximum LVMT at the mid-cavity for women/men were 7mm/9mm (long axis) and 7mm/8mm (short axis). Mean LVMT was positively associated with weight (0.02mm/kg, p=0.01) and body-surface-area (1.1mm/m2, p<0.001). No relationship was found between mean LVMT and age or height. Greater mean LVMT was associated with lower LV end-diastolic volume (0.01mm/ml, p<0.01), a lower LV end-systolic volume (−0.01mm/ml, p=0.01) and lower LV stroke volume (−0.01mm/ml, p<0.05). LVMT measured on long axis images at the basal and mid-cavity level were slightly greater (by 6% and 10%, respectively) than measurements obtained on short axis images; apical LVMT values on long axis images were 20% less than those on short axis images. Conclusion Normal values for wall thickness are provided for middle-aged and older subjects. Normal LVMT is lower for women than men. Observed values vary depending on the imaging plane for measurement.

LV function is generally assessed independent of structural remodeling and vice versa. The purpose of this study was to evaluate a novel LV global function index (LVGFI) that integrates LV structure with global function and to assess its predictive value for cardiovascular (CV) events throughout adult life in a multi-ethnic population of men and women without history of cardiovascular diseases at baseline. A total of 5004 participants in the Multi-Ethnic Study of Atherosclerosis underwent a cardiac magnetic resonance (CMR) study and were followed up for a median of 7.2 years. The LVGFI by CMR was defined by the ratio of stroke volume divided by LV total volume defined as the sum of mean LV cavity and myocardial volumes. Cox proportional hazard models were constructed to predict the end points of heart failure (HF), hard CV events and a combined endpoint of all CV events after adjustment for established risk factors, calcium score and biomarkers. A total of 579 (11.6%) incident events were observed during the follow-up period. In adjusted models, the end points of HF, hard CV events and all events were all significantly associated with LVGFI (HF, hazard ratio [HR]= 0.64, p<0.0001; hard CV events, HR=0.79, p=0.007; all events, HR=0.79, p<0.0001). LVGFI had a significant independent predictive value in the multivariable models for all CV event categories. The LVGFI was a powerful predictor of incident heart failure, hard CV events and a composite endpoint including all events in this multiethnic cohort.