Left Ventricular Native T1 Research Articles

Early Detection of Myocardial Involvement in Thalassemia Intermedia Patients: Multiparametric Mapping by Magnetic Resonance Imaging.

No study has assessed myocardial T1 and T2 values in patients with beta-thalassemia intermedia (β-TI). To assess the prevalence of myocardial involvement in β-TI patients by T2* relaxometry and native T1 and T2 mapping and to determine the correlation of myocardial relaxation times with demographic and clinical parameters. Prospective matched-cohort study. 42 β-TI patients (27 females, 39.65 ± 12.32 years), enrolled in the Extension-Myocardial Iron Overload in Thalassaemia Network, and 42 age- and sex-matched healthy volunteers (27 females, 40.01 ± 11.36 years) and thalassemia major (TM) patients (27 females, 39.27 ± 11.57 years). 1.5 T/multi-echo gradient echo, modified Look-Locker inversion recovery, multi-echo fast-spin-echo, cine balanced steady-state-free precession, and late gadolinium enhancement (LGE) sequences. Hepatic, pancreatic, and left ventricular (LV) T2* values, LV native T1 and T2 values, biventricular ejection fractions and volumes, and presence and extent of replacement myocardial fibrosis. Comparisons between two groups were performed with two-sample t tests, Wilcoxon's signed rank tests, or χ2 testing. Correlation analysis was performed using Pearson's or Spearman's test. P < 0.05 was considered statistically significant. β-TI patients had significantly higher LV T2 values than healthy subjects (56.84 ± 4.03 vs. 52.46 ± 2.50 msec, P < 0.0001) and significantly higher LV T1 values than TM patients (1018.32 ± 48.94 vs. 966.66 ± 66.47 msec, P < 0.0001). In β-TI, female gender was associated with significantly increased LV T1 (P = 0.041) and T2 values (P < 0.0001), while splenectomy and presence of regular transfusions were associated with significantly lower LV T1 values (P = 0.014 and P = 0.001, respectively). In β-TI patients, all LV relaxation times were significantly correlated with each other (T2*-T1: P = 0.003; T2*-T2: P = 0.003; T1-T2: P < 0.0001). Two patients with a reduced LV T2* also had a reduced LV T1, while only one had a reduced LV T2. Three patients had a reduced LV T1 but a normal LV T2*; 66.7% of the patients had an increased LV T2. All LV relaxation times were significantly correlated with pancreas T2* values (T2*: P = 0.033; T1: P < 0.0001; T2: P = 0.014). No LV relaxation time was associated (P > 0.05) with hepatic iron concentration, biventricular function parameters, or LGE presence. The combined use of all three myocardial relaxation times has potential to improve sensitivity in the detection of early/subclinical myocardial involvement in β-Tl patients. 2 TECHNICAL EFFICACY: Stage 2.

Ultrastructural myocardial changes in patients with severe aortic stenosis referred for surgical aortic valve replacement

Abstract Structural myocardial adaptation to pressure overload such as severe aortic stenosis (AS) goes further beyond cardiomyocyte hypertrophy. Progressive fibrosis takes part in left ventricular (LV) remodeling and drives the transition to heart failure. However, the mechanisms underlying this are not fully clarified. Aim To assess ultrastructural myocardial changes occurring in patients with severe AS referred for surgical aortic valve replacement (SAVR). Methods Prospective study of 158 patients (70.9±7.8y, 50%women), with severe symptomatic AS (mean gradient: 60.9±17.4mmHg; valve area: 0.72±0.17cm2; all with high gradient) referred for SAVR with no history of ischemic cardiomyopathy. All patients had complete pre-operative transthoracic echo (LV ejection fraction: 58.9±9.2%; GLS:-14.9±3.7%) and cardiac magnetic resonance with tissue characterization: LV mass index: 80.1±5.9g/m2. Myocardial samples were obtained in 99 patients (62.3%) from intraoperative septal biopsy. Tissue was stained with Verhoeff and Masson´s trichrome for elastic fibers and myocardial fibrosis (MF) assessment, respectively. MF was quantified at an automatic algorithm (QuPath). Inflammation was searched through CD45, CD3, CD20 and CD68 immunostaining. Extracellular matrix (ECM) characterization was performed in 34 samples (alpha-actin, type I collagen, fibronectin and tenascin C immunostaining). Results Mid-wall late gadolinium enhancement was present in 103 patients (65,1%) with a median fraction of 1.9%[IQR 0,1-6,0%] of LV mass. Global LV native T1 and T2 values and extracellular volume fraction were within normal ranges (1057.8±75.4ms, 39.9±4.3ms, 24.7±6.2%, respectively). At histopathology (sample size: 2,446mm [IQR 1,790-3,350mm]) there was cardiomyocyte hypertrophy (median diameter 35mm[IQR 30.2-42.0mm])(Fig, A), variable elastic deposition (elastic endocardium ratio 0.40[IQR 0.2-0.5])(Fig, B), predominant perivascular fibrosis (93.9%) (Fig, C), with a median MF of 13.3% [IQR 7.1-21.0%];57.6% of the patients with dysplastic vessels (Fig, C). Cardiomyocyte enlargement, cytoplasmatic vacuolization and myofiber detachment occurred in 40 cases (40.4%) (Fig, D). This was confirmed as stunning at Periodic acid-Schiff-diastase stain. Inflammation was considered absent in all cases as inflammatory cells were scantily present (median number of CD45+ cells/field: 3[IQR 1.35-6.0]; predominant CD3+). Type I collagen matched MF distribution, following vessel web, such as fibronectin (Fig, E-H). Alpha-actin was detected at the subendocardium in 2/3 of the cases; tenascin C was diffusely positive in 9 cases (27%)(Fig, I). Conclusion These patients with classical severe symptomatic AS were referred for SAVR with diverse ultrastructural myocardial changes. Myocardial stunning occurs in a significant proportion of patients despite the absence of ischemic cardiomyopathy. Inflammation is not involved at this stage of the disease. Distinct grades of ECM remodeling are probably occurring.Figure

Left ventricular thrombus after acute ST-segment elevation myocardial infarction: multi-parametric cardiac magnetic resonance imaging with long-term outcomes.

Left ventricular thrombus (LVT) after acute ST-segment elevation myocardial infarction (STEMI) are generally associated with poorer outcomes for patients at long-term follow-up. We hypothesis that tissue characteristics and strain parameters by cardiac magnetic resonance (CMR) imaging may indicate the interactions of LVT with ventricular myocardium remodeling at both acute stage and chronic stages in STEMI patients. This retrospective study included 111 consecutive STEMI patients (38 with LVT and 73 without LVT). All patients underwent CMR during acute stage (within 7days) and chronic stage (after at least 2months) periods after percutaneous coronary intervention (PCI). Left ventricular native T1, extracellular volume (ECV), radial, circumferential, and longitudinal strain were analyzed in both phases. Major adverse cardiac events (MACE, including cardiovascular death, myocardial reinfarction, and hospitalization for heart failure), thromboembolic and bleeding events, were the clinical endpoints of the study. During the acute stage, left ventricular ejection fraction (LVEF) (OR 0.77, P value = 0.01) and longitudinal strain (OR 1.90, P value < 0.001) were correlated with LVT formation. Strain parameters were reduced, while the native T1 and ECV values of both the infarcted area and remote myocardium were elevated in LVT patients. During the chronic stage, LVT resolved in 29 of 38 patients (76%). LVT remaining patients had lower LVEF, a larger LV, and higher ECV in the acute stage than those of the LVT-resolved patients. In the long-term follow up of 678days, LVT (HR 2.45, P value = 0.02), aneurysm (HR 1.81, P value = 0.04), and native T1 (HR 2.44, P value = 0.01) were identified as three independent predictors of MACE, the incidence of thromboembolic events and bleeding events by a multivariable stepwise Cox proportional hazards regression. STEMI patients developing LVT had worse LV function, myocardial infarction extent, strain, and higher T1 and ECV values than STEMI patients without LVT. The LVT-remaining patients in the chronic stage had poorer functional and mapping parameters beginning in the first week. During the acute stage, LVEF and global longitudinal strain were independent correlated with LVT formation. During the long-term follow up, LVT, aneurysm and elevated myocardial T1 were associated with adverse outcomes in acute STEMI patients.

Differential myocardial fibrosis of the systemic right ventricle and subpulmonary left ventricle after atrial switch operation for complete transposition of the great arteries.

This study aimed to assess diffuse myocardial fibrosis of the systemic right ventricle and subpulmonary left ventricle in patients after Senning or Mustard operation for complete transposition of the great artery (TGA) using cardiac magnetic resonance (CMR) T1 mapping. Thirty-one adult TGA patients after Senning (n=24) or Mustard (n=7) operation were studied at the age of 33.3±4.0years. Systemic right ventricular (RV) and subpulmonary left ventricular (LV) volumes, ejection fraction, and myocardial T1 values and extracellular volume fraction (ECV) were determined using CMR. The RV and LV ejection fractions were 47.0±10.9% and 61.3±7.4%, respectively. Compared to published normative values, patients had significantly greater RV and LV native T1 and ECV values (all p<0.001). For each of the basal, mid, and apical segments, the LV native T1 and ECV values were significantly greater in the left than the right ventricle (all p<0.05). There is a significant trend on progressive increase in ECV value from the basal towards the apical segments in both the right (p=0.002) and the left (p<0.001) ventricle. Modestly strong correlations were found between RV and LV native T1 (r=0.60, p<0.001) and ECV (r=0.49, p=0.005) values but not with ejection fractions of the respective ventricles. Differential myocardial fibrosis, with greater involvement of the subpulmonary left ventricle than the systemic right ventricle, is present in patients with TGA after atrial switch operation. Associations between the magnitude of RV and LV fibrosis suggests adverse ventricular-ventricular interaction at the cardiac extracellular matrix level.

Radiomic Analysis of Native T1 Mapping Images Discriminates Between MYH7 and MYBPC3-Related Hypertrophic Cardiomyopathy.

The phenotype via conventional cardiac MRI analysis of MYH7 (β-myosin heavy chain)- and MYBPC3 (β-myosin-binding protein C)-associated hypertrophic cardiomyopathy (HCM) groups is similar. Few studies exist on the genotypic-phenotypic association as assessed by machine learning in HCM patients. To explore the phenotypic differences based on radiomics analysis of T1 mapping images between MYH7 and MYBPC3-associated HCM subgroups. Prospective observational study. In all, 102 HCM patients with pathogenic, or likely pathogenic mutation, in MYH7 (n = 68) or MYBPC3 (n = 34) genes. Cardiac MRI was performed at 3.0T with balanced steady-state free precession (bSSFP), phase-sensitive inversion recovery (PSIR) late gadolinium enhancement (LGE), and modified Look-Locker inversion recovery (MOLLI) T1 mapping sequences. All patients underwent next-generation sequencing and Sanger genetic sequencing. Left ventricular native T1 and LGE were analyzed. One hundred and fifty-seven radiomic features were extracted and modeled using a support vector machine (SVM) combined with principal component analysis (PCA). Each subgroup was randomly split 4:1 (feature selection / test validation). Mann-Whitney U-tests and Student's t-tests were performed to assess differences between subgroups. A receiver operating characteristic (ROC) curve was used to assess the model's ability to stratify patients based on radiomic features. There were no significant differences between MYH7- and MYBPC3-associated HCM subgroups based on traditional native T1 values (global, basal, and middle short-axis slice native T1 ; P = 0.760, 0.914, and 0.178, respectively). However, the SVM model combined with PCA achieved an accuracy and area under the curve (AUC) of 92.0% and 0.968 (95% confidence interval [CI]: 0.968-0.971), respectively. For the test validation dataset, the accuracy and AUC were 85.5% and 0.886 (95% CI: 0.881-0.901), respectively. Radiomic analysis of native T1 mapping images may be able to discriminate between MYH7- and MYBPC3-associated HCM patients, exceeding the performance of conventional native T1 values. 3 TECHNICAL EFFICACY STAGE: 2 J. MAGN. RESON. IMAGING 2020;52:1714-1721.

Focal scar and diffuse myocardial fibrosis are independent imaging markers in repaired tetralogy of Fallot.

AimsTo identify the correlates of focal scar and diffuse fibrosis in patients with history of tetralogy of Fallot (TOF) repair.Methods and resultsConsecutive patients with prior TOF repair underwent electrocardiogram, 24-h Holter, transthoracic echocardiography, exercise testing, and cardiac magnetic resonance (CMR) including cine imaging to assess ventricular volumes and ejection fraction, T1 mapping to assess left ventricular (LV) and right ventricular (RV) diffuse fibrosis, and free-breathing late gadolinium-enhanced imaging to quantify scar area at high spatial resolution. Structural imaging data were related to clinical characteristics and functional imaging markers. Cine and T1 mapping results were compared with 40 age- and sex-matched controls. One hundred and three patients were enrolled (age 28 ± 15 years, 36% women), including 36 with prior pulmonary valve replacement (PVR). Compared with controls, TOF showed lower LV ejection fraction (LVEF) and RV ejection fraction (RVEF), and higher RV volume, RV wall thickness, and native T1 and extracellular volume values on both ventricles. In TOF, scar area related to LVEF and RVEF, while LV and RV native T1 related to RV dilatation. On multivariable analysis, scar area and LV native T1 were independent correlates of ventricular arrhythmia, while RVEF was not. Patients with history of PVR showed larger scars on RV outflow tract but shorter LV and RV native T1.ConclusionFocal scar and biventricular diffuse fibrosis can be characterized on CMR after TOF repair. Scar size relates to systolic dysfunction, and diffuse fibrosis to RV dilatation. Both independently relate to ventricular arrhythmias. The finding of shorter T1 after PVR suggests that diffuse fibrosis may reverse with therapy.

Reverse left ventricular structural remodeling after catheter ablation of atrial fibrillation in patients with preserved left ventricular function: Insights from cardiovascular magnetic resonance native T1 mapping

Catheter ablation of atrial fibrillation (AF) improves left ventricular (LV) function in patients with LV systolic dysfunction, suggestive of underlying arrhythmia-induced adverse remodeling. The objectives of this study were to evaluate whether arrhythmia-induced LV remodeling occurs in patients with AF and preserved LV systolic function and to assess whether this remodeling is reversible after restoration of sinus rhythm by catheter ablation. Forty-three patients with AF and preserved LV systolic function (LV ejection fraction 62% ± 7%) underwent cardiovascular magnetic resonance (CMR) imaging before catheter ablation including native T1 mapping using a modified Look-Locker inversion recovery sequence. Twenty-five patients underwent follow-up CMR 3 months after catheter ablation. Twenty-two matched controls without AF underwent the same CMR protocol. Patients with AF had higher baseline LV native T1 values than did controls (1296 ± 55 ms vs 1243 ± 55 ms; P < .01). During a median follow-up of 9 months (interquartile range 4-14 months), 17 patients (40%) experienced AF recurrence. No differences in baseline T1 values were observed between patients with and without AF recurrence. There was a significant decrease in native T1 values in patients with successful restoration of sinus rhythm after catheter ablation at 3 months of follow-up CMR (1300 ± 45 ms vs 1270 ± 55 ms; P < .01), while they remain unchanged in patients with AF recurrence (1303 ± 51 ms vs 1309 ± 31 ms; P= .64). These preliminary results suggest that subclinical arrhythmia-induced LV structural remodeling occurs in patients with AF and preserved LV systolic function. This remodeling might be reversible after catheter ablation with successful restoration of sinus rhythm as quantified noninvasively and gadolinium-free by CMR native T1 mapping.

Left ventricular remodelling in long-term survivors after the arterial switch operation for transposition of the great arteries.

The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO). Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort. Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.

Use of Myocardial T1 Mapping at 3.0 T to Differentiate Anderson-Fabry Disease from Hypertrophic Cardiomyopathy.

Purpose To compare left ventricular (LV) and right ventricular (RV) 3.0-T cardiac magnetic resonance (MR) imaging T1 values in Anderson-Fabry disease (AFD) and hypertrophic cardiomyopathy (HCM) and evaluate the diagnostic value of native T1 values beyond age, sex, and conventional imaging features. Materials and Methods For this prospective study, 30 patients with gene-positive AFD (37% male; mean age ± standard deviation, 45.0 years ± 14.1) and 30 patients with HCM (57% male; mean age, 49.3 years ± 13.5) were prospectively recruited between June 2016 and September 2017 to undergo cardiac MR imaging T1 mapping with a modified Look-Locker inversion recovery (MOLLI) acquisition scheme at 3.0 T (repetition time msec/echo time msec, 280/1.12; section thickness, 8 mm). LV and RV T1 values were evaluated. Statistical analysis included independent samples t test, receiver operating characteristic curve analysis, multivariable logistic regression, and likelihood ratio test. Results Septal LV, global LV, and RV native T1 values were significantly lower in AFD compared with those in HCM (1161 msec ± 47 vs 1296 msec ± 55, respectively [P < .001]; 1192 msec ± 52 vs 1268 msec ± 55 [P < .001]; and 1221 msec ± 54 vs 1271 msec ± 37 [P = .001], respectively). A septal LV native T1 cutoff point of 1220 msec or lower distinguished AFD from HCM with sensitivity of 97%, specificity of 93%, and accuracy of 95%. Septal LV native T1 values differentiated AFD from HCM after adjustment for age, sex, and conventional imaging features (odds ratio, 0.94; 95% confidence interval: 0.91, 0.98; P = < .001). In a nested logistic regression model with age, sex, and conventional imaging features, model fit was significantly improved by the addition of septal LV native T1 values (χ2 [df = 1] = 33.4; P < .001). Conclusion Cardiac MR imaging native T1 values at 3.0 T are significantly lower in patients with AFD compared with those with HCM and provide independent and incremental diagnostic value beyond age, sex, and conventional imaging features. © RSNA, 2018.

Assessment of Diffuse Ventricular Myocardial Fibrosis Using Native T1 in Children With Repaired Tetralogy of Fallot.

Myocardial fibrosis is linked with adverse clinical outcomes in adults after tetralogy of Fallot repair (rTOF). Native T1 times (T1) by cardiac magnetic resonance have been shown to be a surrogate marker of diffuse myocardial fibrosis. The objective was to quantify native T1 in children post-rTOF and to evaluate their relationship with surgical, imaging, and clinical factors. A retrospective cross-sectional study was performed. Midventricular native T1 were obtained in 100 children post-rTOF using a modified look-locker inversion recovery cardiac magnetic resonance sequence and compared with 35 pediatric controls. rTOF patients, aged 13.0±2.9 years, had higher indexed right ventricular (RV) end-diastolic (range 85-326 mL/m2, mean 148 mL/m2) volumes, and lower RV and left ventricular (LV) ejection fractions compared with controls. RV, but not LV, T1 were higher in patients than in controls (1031±74 versus 954±32 ms, P<0.001) and female patients had higher RV T1 compared with males (1051±79 versus 1017±68 ms, P=0.02). LV T1 correlated with RV T1 (r=0.45, P<0.001), cardiopulmonary bypass (r=0.30, P=0.007), and aortic cross-clamp times (r=0.32, P=0.004). RV T1 correlated inversely with RV outflow tract gradient (r=-0.28, P=0.02). Longer aortic cross-clamp times were independently associated with LV and RV T1 on multivariable analysis. There was no association between exercise intolerance, arrhythmia, and native T1 or LV extracellular volume. Children after rTOF do not have elevated LV native T1 or LV extracellular volume, but show evidence of increased RV native T1 suggestive of diffuse RV fibrosis, for which volume loading seems to be a risk factor. Surgical bypass and cross-clamp times are associated with fibrotic remodeling over a decade later.

T1 mapping in children and young adults with hypertrophic cardiomyopathy.

To assess the global and segmental left ventricular (LV) native T1 and extracellular volume fraction (ECV) in children and young adults with hypertrophic cardiomyopathy (HCM) compared to a control cohort. The study population included 21 HCM patients (mean 14.1 ± 4.6 years) and 21 controls (mean 15.7 ± 1.5 years). Native modified Look-Locker inversion recovery sequence was performed before and after contrast injection in 3 short axis planes. Global and segmental LV native T1 and ECV were quantified and compared between HCM patients and controls. Mean native T1 in HCM patients and controls was 1020.4 ± 41.2 and 965.6 ± 30.2ms respectively (p < 0.0001). Hypertrophied myocardium had significantly higher native global T1 and global ECV compared to non-hypertrophied myocardium in HCM (p < 0.0001, = 0.14 and 0.048, = 0.01 respectively). In a subset of patients, ECV was higher in LV segments with LGE compared to no LGE (p < 0.0001). No significant correlation was identified between global native T1 and ECV and parameters of LV structure and function. Native T1 cut-off of 987ms provided the highest sensitivity (95 %) and specificity (91 %) to separate HCM patients from controls. Global and segmental native T1 are elevated in HCM patients. LV segments with hypertrophy and/or LGE had higher ECV in a subset of HCM patients. LV native T1 and ECV do not correlate with parameters of LV structure and function. T1 in children and young adults may be used as a non-invasive tool to assess for HCM and related fibrosis.

Myocardial Native T1 Time in Patients With Hypertrophic Cardiomyopathy

In hypertrophic cardiomyopathy (HC), there are significant variations in left ventricular (LV) wall thickness and fibrosis, which necessitates a volumetric coverage. Slice-interleaved T1 (STONE) mapping sequence allows for the assessment of native T1 time with complete coverage of LV myocardium. The aims of this study were to evaluate spatial heterogeneity of native T1 time in patients with HC. Twenty-nine patients with HC (55 ± 16years) and 15 healthy adult control subjects (46 ± 19years) were studied. Native T1 mapping was performed using STONE sequence which enables acquisition of 5 slices in the short-axis plane within a 90seconds free-breathing scan. We measured LV native T1 time and maximum LV wall thickness in each 16 segments from 3 slices (basal, midventricular and apical slice). Late gadolinium enhanced (LGE) magnetic resonance imaging was acquired to assess the presence of myocardial enhancement. In patients with HC, LV native T1 time was significantly elevated compared with healthy controls, regardless of the presence or absence of LGE (mean native T1 time; LGE positive segments from HC, 1,141 ± 46 ms; LGE negative segments from HC, 1,114 ± 56 ms; segments from healthy controls, 1,065 ± 35 ms, p <0.001). Elevation of native T1 time was defined as >1,135 ms, which was+2SD of native T1 time by STONE sequence in healthy controls. A total of 120 of 405 (30%) LGE negative segments from patients with HC showed elevated native T1 time. Prevalence of segments with elevated native T1 time for basal, midventricular, and apical slice was 29%, 25%, 38%, respectively. Significant correlation was found between LV wall thickness and LV native T1 time (y= 0.029×-22.6, p <0.001 by Spearman's correlation coefficient). In conclusion, substantial number of segments without LGE showed elevation of native T1 time, and whole-heart T1 mapping revealed heterogeneity of myocardial native T1 time in patients with HC.

Native T1 mapping in children and young adults with hypertrophic cardiomyopathy

To assess the global and segmental left ventricular (LV) native T1 and extracellular volume fraction (ECV) in children and young adults with hypertrophic cardiomyopathy (HCM) compared to a control cohort. The study population included 21 HCM patients (mean 14.1 ± 4.6 years) and 21 controls (mean 15.7 ± 1.5 years). Native modified Look-Locker inversion recovery sequence was performed before and after contrast injection in 3 short axis planes. Global and segmental LV native T1 and ECV were quantified and compared between HCM patients and controls. Mean native T1 in HCM patients and controls was 1020.4 ± 41.2 and 965.6 ± 30.2 ms respectively (p < 0.0001). Hypertrophied myocardium had significantly higher native global T1 and global ECV compared to non-hypertrophied myocardium in HCM (p < 0.0001, = 0.14 and 0.048, = 0.01 respectively). In a subset of patients, ECV was higher in LV segments with LGE compared to no LGE (p < 0.0001). No significant correlation was identified between global native T1 and ECV and parameters of LV structure and function. Native T1 cut-off of 987 ms provided the highest sensitivity (95 %) and specificity (91 %) to separate HCM patients from controls. Global and segmental native T1 are elevated in HCM patients. LV segments with hypertrophy and/or LGE had higher ECV in a subset of HCM patients. LV native T1 and ECV do not correlate with parameters of LV structure and function. T1 in children and young adults may be used as a non-invasive tool to assess for HCM and related fibrosis.

Abstract 15137: Detection of Diffuse Myocardial Fibrosis using Multi-slice T1 Mapping by Slice Interleaved T1 (STONE) Sequence in Patients With Hypertrophic Cardiomyopathy

Introduction: In hypertrophic cardiomyopathy (HCM), there are significant variations in left ventricular (LV) wall thickness and fibrosis, which necessitates a volumetric coverage. Slice-interleaved T1 (STONE) mapping sequence allows for the assessment of native T1 time with complete coverage of LV myocardium. Hypothesis: We hypothesized that STONE sequence is useful for the assessment of regional native T1 time abnormality in HCM patients. Methods: Twenty-four septal HCM patients (56±16 years) and 10 healthy adult control subjects (57±15 years) were studied. Native T1 mapping was performed using STONE sequence which enables acquisition of 5 slices in the short-axis plane within a 90 sec free-breathing scan. We measured LV native T1 time and maximum LV wall thickness in each 16 segments from 3 slices (basal-, mid- and apical-slice) and evaluated the relationship between LV native T1 time and wall thickness. Late gadolinium enhanced (LGE) MRI was acquired to assess presence of myocardial enhancement. Results: In HCM patients, LV native T1 time was significantly elevated compared to healthy controls, regardless of presence or absence of LGE (mean native T1 time; LGE (+) segments (n=27), 1139±55 msec; LGE (-) segments (n=351), 1118±55 msec; healthy control (n=160),1065±35 msec; p&lt;0.001 by one-way ANOVA, 6 segments were excluded from analysis due to artifacts). Among 351 segments without LGE, native LV T1 time was diffusely elevated over the 16 segments (Figure). Significant positive correlation was found between LV wall thickness and native LV T1 time (y=1013+8.7x, p&lt;0.001). Conclusions: In HCM, substantial number of segments without LGE showed elevated native T1 time, and native T1 time was correlated with LV wall thickness. Multi-slice T1 mapping by using STONE sequence could be advantageous to overcome limited cardiac coverage of conventional single-slice T1 mapping technique and to accurately detect the diffuse myocardial fibrosis in HCM patients.