Myocardial T2 values by a segmental approach with healthy ageing and gender

Funding Acknowledgements Type of funding sources: None. Introduction. No data are available in literature about normal ranges for T2 in human myocardium using GE scanners. Aims. Our aims were to obtain myocardial regional and global T2 values as a reference for normality for the first time using a GE scanner and to assess their association with physiological variables. Methods. A stratified approach was adopted for healthy volunteers recruitment, ensuring the presence of 10 participants for both genders in each age decile: 20–30, 30–40, 40-50, 50-60, 60-70 years. Basal, medium, and apical short-axis slices of the left ventricle were acquired by a multi-echo fast-spin-echo (MEFSE) sequence. Image analysis was performed with a commercially available software package. T2 value was assessed in all 16 myocardial segments and global value was the mean. Results. The global T2 value averaged across all subjects was 52.2 ± 2.5 ms (range: 47.0-59.9 ms). Inter-study, intra-observer, and inter-observer reproducibility was good (coefficient of variation < 5%). The 3.6% of segments was excluded because of artifacts and/or partial-volume effects. Segmental T2 values differed significantly (P < 0.0001), with the lowest value in the basal anterolateral segment (50.0 ± 3.5 ms) and the highest in the apical lateral segment (54.9 ± 5.1 ms). Mean T2 was significantly lower in the basal slice compared to both medium (51.0 ± 2.4 vs 51.8 ± 2.6 ms; P < 0.0001) and apical slices (51.0 ± 2.4 vs 54.2 ± 3.7 ms; P < 0.0001), and in the medium slice than in the apical slice (51.8 ± 2.6 vs 54.2 ± 3.7 ms; P < 0.0001). Aging was associated with increased segmental and global T2 values. Females showed higher T2 values than males. T2 values were not correlated to heart rate. Mean T2 values, standard deviation, and lower and upper limits of normal for all 16 myocardial segments are shown in Figure 1 for males and in Figure 2 for females, considering separately each age group. Conclusion. The optimized MEFSE sequence allows for robust, reliable, and reproducible quantification of segmental T2 values. T2 values differ among myocardial slices and are influenced by age and gender, making mandatory to define gender- and age-specific segmental reference values for distinguishing between healthy and diseased myocardium. The normal ranges defined in this study on a large cohort of healthy subjects could be used as reference by other sites using the same sequence, allowing them to recruit a smaller population and accelerating the spread of myocardial T2 mapping in the clinical arena.

Evolution of biventricular T1 values in patients with right-sided congenital heart disease

Funding Acknowledgements Type of funding sources: None. Background Conflicting reports exist on the prevalence and clinical impact of interstitial fibrosis in right ventricular (RV) congenital heart disease (CHD). This study evaluates the longitudinal evolution of native myocardial T1 relaxation time (T1) in RV CHD. Methods On a 1.5T scanner, an ECG-triggered modified Look-Locker inversion recovery sequence (scheme 3(3)3(3)5) was acquired on a short-axis basal slice covering the RV and left ventricle (LV) on two consecutive CMR exams. Global and segmental (LV = 6, RV = 4) RV and LV T1 values were calculated (Figure). Results Mean time between CMR exams for 36 included patients (age 34 ± 2y) was 22 ± 2 months. All LV segments and 81/88% of RV segments of first and second CMR could be analyzed, respectively. T1 increased mildly but not significantly (table). There was no relationship of T1 to pulmonary regurgitation fraction, pulmonary stenosis or RV enddiastolic volume (p > 0.05). Global RV T1 of the second CMR was related to RV ejection fraction (RVEF): r = 0.353, 3.0 ± 1.4, p = 0.038. T1 of the infero-septal LV segment of first and second CMR, global LV T1 of second CMR and increase of T1 of global LV, anterior, antero-lateral and –septal LV segments, were related to age at CMR: r = 0.333 - 0.463, p < 0.05, respectively. Conclusions Native T1 values increased mildly in patients with stable RV CHD, which was not statistically significant probably due to the short to median follow-up. Global RV T1 appears to be related to RVEF which could be sign of increasing interstitial fibrosis whereas the relationship of LV T1 to age might be a physiological finding. First CMR native T1 (ms) Second CMR native T1 (ms) p LV Global 1007 ± 37 1014 ± 39 0.413 LV Anterior 994 ± 53 999 ± 54 0.710 LV Antero-lateral 965 ± 63 981 ± 58 0.186 LV Infero-lateral 1000 ± 52 1004 ± 63 0.695 LV Inferior 1035 42 1037 ± 50 0.744 LV Infero-septal 1028 ± 35 1036 ± 43 0.282 LV Antero-septal 1016 ± 38 1024 ± 48 0.347 RV Global 1091 ± 90 1096 ± 85 0.410 RV Inferior 1112 ± 104 1115 ± 118 0.696 RV Infero-lateral 1061 ± 130 1077 ± 115 0.425 RV Antero-lateral 1046 ± 127 1080 ± 109 0.088 RV Anterior 1088 ± 156 1108 ± 154 0.410 Abstract Figure. Determination of biventricular T1 values

Constraints on the P–T conditions and age of emplacement of the Lizard ophiolite, Cornwall: amphibole–plagioclase thermobarometry and 40Ar/39Ar geochronology of basal amphibolites

The basal slice of the Lizard Complex incorporates strongly foliated amphibolitic metabasites (Lower Landewednack Schists), interpreted as the remnants of a dynamothermal aureole formed beneath the ophiolite during intraoceanic thrusting. Structurally overlying the basal slice and occurring predominantly within the overlying Lizard peridotite is the Kennack Gneiss, a controversial, banded and gneissose unit comprising intimately mixed amphibolitic and granitic components, interpreted to represent commingled melts. Thermobarometry of hornblende–plagioclase pairs indicates that both the Landewednack Schists and the mafic component of the Kennack Gneiss recrystallized synkinematically at ca. 600 °C and 300–400 MPa. Three amphiboles, two from the Kennack Gneiss and one from the Landewednack Schists, yield disturbed 40Ar/39Ar age spectra characterized by low-temperature overprinting, but with good high-temperature plateaux with ages of 366.1 ± 4.2, 364.2 ± 4.8, and 359.8 ± 7.4 Ma, respectively. Theoretical diffusion modelling of the first of these spectra, based on a spherical geometry, indicates that it is best described by a 13% loss of argon during a thermal overprint, at ~220 Ma, on a primary cooling age (~500 °C) of 370 Ma. As has been documented in many ophiolite massifs, displacement of the Lizard Complex probably occurred promptly after its initial formation, but the imprecise crystallization age (ca. 375 ± 34 Ma) precludes construction of a precise cooling history.