Cardiovascular Magnetic Resonance T1 Mapping Research Articles

Extracellular volume quantification by cardiac magnetic resonance imaging without hematocrit sampling : Ready for prime time?

SummaryBackgroundMyocardial tissue characterization by cardiovascular magnetic resonance (CMR) T1 mapping currently receives increasing interest as a diagnostic tool in various disease settings. The T1-mapping technique allows non-invasive estimation of myocardial extracellular volume (ECV) using T1-times before and after gadolinium administration; however, for calculation of the myocardial ECV the hematocrit is needed, which limits its utility in routine application. Recently, the alternative use of the blood pool T1-time instead of the hematocrit has been described.MethodsThe results of CMR T1 mapping data of 513 consecutive patients were analyzed for this study. Blood for hematocrit measurement was drawn when placing the i. v. line for contrast agent administration. Data from the first 200 consecutive patients (derivation cohort) were used to establish a regression formula allowing synthetic hematocrit calculation, which was then validated in the following 313 patients (validation cohort). Synthetic ECV was calculated using synthetic hematocrit, and was compared with conventionally derived ECV.ResultsAmong the entire cohort of 513 patients (mean age 57.4 ± 17.5 years old, 49.1% female) conventionally measured hematocrit was 39.9 ± 4.7% and native blood pool T1-time was 1570.6 ± 117.8 ms. Hematocrit and relaxivity of blood (R1 = 1/blood pool T1 time) were significantly correlated (r = 0.533, r2 = 0.284, p < 0.001). By linear regression analysis, the following formula was developed from the derivation cohort: synthetic hematocrit = 628.5 × R1 − 0.002. Synthetic and conventional hematocrit as well as ECV showed significant correlation in the validation (r = 0.533, r2 = 0.284, p < 0.001 and r = 0.943, r2 = 0.889, p < 0.001, respectively) as well as the overall cohort (r = 0.552, r2 = 0.305, p < 0.001 and r = 0.957, r2 = 0,916, p < 0.001). By Bland Altman analysis, good agreement between conventional and synthetic ECV was found in the validation cohort (mean difference: 0.007%, limits of agreement: −4.32 and 4.33%, respectively).ConclusionSynthetic ECV using native blood pool T1-times to calculate the hematocrit, is feasible and leads to almost identical results in comparison with the conventional method. It may allow fully automatic ECV-mapping and thus enable broader use of ECV by CMR T1 mapping in clinical practice.

P3265T1 and T2 mapping cardiovascular magnetic resonance is not able to differentiate between infarcted and salvaged myocardium in reperfused STEMI patients

P3265T1 and T2 mapping cardiovascular magnetic resonance is not able to differentiate between infarcted and salvaged myocardium in reperfused STEMI patients

Elevated Myocardial Extracellular Volume Fraction in Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a genetic, X-linked recessive disease with an associated cardiomyopathy characterized by myocardial fibrosis leading to heart failure, arrhythmias, and death. Earlier detection and treatment of cardiac involvement in DMD hold potential to improve outcomes. Cardiovascular magnetic resonance (CMR) extracellular volume (ECV) quantification using T1 mapping is a histologically validated, non-invasive marker of diffuse fibrosis. This study aims to determine the ECV in a pediatric DMD population, and correlate it with metrics of left ventricular function. A retrospective review of pediatric DMD subjects who underwent CMR at a single institution. A total of 47 DMD patients (mean age 14±2years) were included for analysis. Global myocardial ECV was significantly higher in the DMD group (29±6%) compared with published normal values (24±2%, p=0.0001). Higher ECV values correlate with indices of left ventricular function, including decreased left ventricular ejection fraction (r=-0.46, p=0.001) and indexed left ventricular end diastolic volume (r=0.41, p=0.004). ECV was not significantly higher in DMD patients with late gadolinium enhancement (LGE) (30±7%) compared to DMD patients without LGE (27±5%, p=0.0717). CMR T1 mapping is a feasible method for quantification of ECV in patients with DMD. Global myocardial ECV is significantly higher in the DMD population compared to healthy controls and correlates with other metrics of myocardial function. Global myocardial ECV may serve as an important tool to determine cardiac involvement in DMD population and help guide medical management.

19 Adverse cardiac remodelling under pressure overload. a magnetic resonance imaging study in mice

Pressure overload, a hallmark of valvular heart disease and hypertension, is the leading cause of heart failure. With the progressive nature of this condition a better understanding of the process underlying the transition to heart failure is vital. Recent studies suggest that interstitial myocardial fibrosis occurs early in this transition and has a profound effect on cardiac function. The recently developed T1-mapping Cardiovascular Magnetic Resonance Imaging (CMR) technique has the potential to quantify the extracellular volume fraction (ECV) and therefore evaluate the expansion of the extracellular matrix (primarily diffuse fibrosis) over time. We aimed to assess the feasibility of CMR (including functional and ECV imaging) to monitor cardiac remodelling using an animal model of pressure overload heart disease. Fifteen mice were subjected to a 6 week Angiotensin-II infusion (AngII). CMR (cine and T1 mapping) was performed before and following Angiotensin II infusion at 2, 4 and 6 weeks. ECV was calculated from the T1 relaxation times pre and post-contrast infusion). Mean blood pressure increased from 65±12 (baseline) to 84±14 mmHg (p Prolonged pressure overload results in ECV expansion, LV hypertrophy and subsequent systolic dysfunction. T1 mapping CMR shows promise in monitoring this transition.

Tissue characterization by T1 and T2 mapping cardiovascular magnetic resonance imaging to monitor myocardial inflammation in healing myocarditis.

Monitoring disease activity in myocarditis is important for tailored therapeutic strategies. This study evaluated the ability of T1 and T2 mapping cardiovascular magnetic resonance (CMR) to monitor the course of myocardial inflammation in healing myocarditis. Forty-eight patients with strictly defined acute myocarditis underwent CMR at 1.5 T in the acute stage, at 3-months (n = 39), and at 12-months follow-up (FU) (n = 21). Normal values were obtained in a control group of 27 healthy subjects. The CMR protocol included standard ('Lake-Louise') sequences as well as T1 (modified Look-Locker inversion recovery sequence, MOLLI) and T2 (gradient- and spin-echo sequence, GraSE) mapping. T1, T2, and extracellular volume (ECV) maps were generated using an OsiriX plug-in. Native myocardial T1, T2, and ECV values were increased in the acute stage, but declined with healing of myocarditis. The performances of global native T1 and T2 to differentiate acute from healed myocarditis stages were significantly better compared with all other global CMR parameters with AUCs of 0.85 (95% CI, 0.76-0.94) and 0.83 (95% CI, 0.73-0.93). Furthermore, regional native T1 and T2 in myocarditis lesions provided AUCs of 0.97 (95% CI, 0.93-1.02) and 0.93 (95% CI, 0.85-1.01), which were significantly superior to any other global or regional CMR parameter. Healing of myocarditis can be monitored by native myocardial T1 and T2 measurements without the need for contrast media. Both native myocardial T1 and T2 provide an excellent performance for assessing the stage of myocarditis by CMR.

Assessment of Diabetic Cardiomyopathy by Cardiovascular Magnetic Resonance T1 Mapping: Correlation with Left-Ventricular Diastolic Dysfunction and Diabetic Duration.

Purpose To quantify extracellular matrix expansion with the cardiovascular magnetic resonance (CMR) T1 mapping technique and the derived extracellular volume fraction (ECV) in diabetic cardiomyopathy (DbCM) patients and to detect the relationship among ECV, duration of diabetes, and diastolic function. Materials Thirty-eight patients with diabetic cardiomyopathy (20 males, age 54.6 ± 8.6 years) and thirty-two matched normal controls (15 males, age 51.4 ± 13.6 years) were prospectively enrolled. All of them were scanned by T1 mapping to obtain the native and postcontrast T1 values of myocardium and blood, and ECV was calculated accordingly. All patients also underwent transthoracic echocardiographic tissue Doppler imaging to assess left-ventricular diastolic function. Results There was a significant difference in ECV between the two groups (DbCMs 30.4 ± 2.9% versus controls 27.1 ± 2.4%, P < 0.001). The duration of diabetes was positively and strongly associated with ECV (R = 0.539, P = 0.0005). There was also a significant difference in ECV (P ≤ 0.001) among four groups (A, controls; B, DbCM patients with duration of diabetes <5 years; C, 5–10 years; and D, >10 years). ECV was negatively associated with LV E'/A' (R = −0.403, P = 0.012). Conclusion CMR T1 mapping can reflect myocardial extracellular matrix expansion in DbCM and can be a powerful technique for the early diagnosis of DbCM.

Abnormal T2 mapping cardiovascular magnetic resonance correlates with adverse clinical outcome in patients with suspected acute myocarditis

BackgroundWhile most patients recover from suspected acute myocarditis (sAMC) some develop progressive disease with 5-year mortality up to 20%. Recently, parametric Cardiovascular Magnetic Resonance (CMR) approaches, quantifying native T1 and T2 relaxation time, have demonstrated the ability to increase diagnostic accuracy. However, prognostic implications of T2 values in this cohort are unknown. The purpose of the study was to investigate the prognostic relevance of elevated CMR T2 values in patients with sAMC.Methods and ResultsWe carried out a prospective study in 46 patients with sAMC defined by current ESC recommendations. A combined endpoint was defined by the occurrence of at least one major adverse cardiac event (MACE) and hospitalisation for heart failure. Event rate was 24% (n = 11) for 1-year-MACE and hospitalisation. A follow-up after 11 ± 7 months was performed in 98% of the patients. Global T2 values were significantly increased at acute stage of disease compared to controls and decreased over time. During acute disease, elevated global T2 time (odds ratio 6.3, p < 0.02) as well as myocardial fraction with T2 time >80 ms (odds ratio 4.9, p < 0.04) predicted occurrence of the combined endpoint. Patients with clinical recovery revealed significantly decreased T2 relaxation times at follow-up examinations; however, T2 values were still elevated compared to healthy controls.ConclusionAssessment of myocardial T2 relaxation times at initial presentation facilitates CMR-based risk stratification in patients with acute myocarditis. T2 Mapping may emerge as a new tool to monitor inflammatory myocardial injuries during the course of disease.

Histological validation of cardiovascular magnetic resonance T1 mapping markers of myocardial fibrosis in paediatric heart transplant recipients

BackgroundAdverse fibrotic remodeling is detrimental to myocardial health and a reliable method for monitoring the development of fibrotic remodeling may be desirable during the follow-up of patients after heart transplantation (HTx). Quantification of diffuse myocardial fibrosis with cardiovascular magnetic resonance (CMR) has been increasingly applied and validated histologically in adult patients with heart disease. However, comparisons of CMR findings with histological fibrosis burden in children are lacking. This study aimed to compare native T1 times and extracellular volume fraction (ECV) derived from CMR with the degree of collagen on endomyocardial biopsy (EmBx), and to investigate the association between myocardial fibrosis and clinical as well as functional markers in children after HTx.MethodsEmBx and CMR were performed on the same day. All specimens were stained with picrosirius red. The collagen volume fraction (CVF) was calculated as ratio of stained collagen area to total myocardial area on EmBx. Native T1 values and ECV were measured by CMR on a mid-ventricular short axis slice, using a modified look-locker inversion recovery approach.ResultsTwenty patients (9.9 ± 6.2 years of age; 9 girls) after HTx were prospectively enrolled, at a median of 1.3 years (0.02–12.6 years) post HTx, and compared to 24 controls (13.9 ± 2.6 years of age; 12 girls). The mean histological CVF was 10.0 ± 3.4%. Septal native T1 times and ECV were higher in HTx patients compared to controls (1008 ± 32 ms vs 979 ± 24 ms, p < 0.005 and 0.30 ± 0.03 vs 0.22 ± 0.03, p < 0.0001, respectively). CVF showed a moderate correlation with native T1 (r = 0.53, p < 0.05) as well as ECV (r = 0.46, p < 0.05). Native T1 time, but not ECV and CVF, correlated with ischemia time (r = 0.46, p < 0.05).ConclusionsCMR-derived fibrosis markers correlate with histological degree of fibrosis on EmBx in children after HTx. Further, native T1 times are associated with longer ischemia times.

Adenosine stress CMR T1-mapping detects early microvascular dysfunction in patients with type 2 diabetes mellitus without obstructive coronary artery disease

BackgroundType 2 diabetes mellitus (T2DM) is associated with coronary microvascular dysfunction in the absence of obstructive coronary artery disease (CAD). Cardiovascular magnetic resonance (CMR) T1-mapping at rest and during adenosine stress can assess coronary vascular reactivity. We hypothesised that the non-contrast T1 response to vasodilator stress will be altered in patients with T2DM without CAD compared to controls due to coronary microvascular dysfunction.MethodsThirty-one patients with T2DM and sixteen matched healthy controls underwent CMR (3 T) for cine, rest and adenosine stress non-contrast T1-mapping (ShMOLLI), first-pass perfusion and late gadolinium enhancement (LGE) imaging. Significant CAD (>50% coronary luminal stenosis) was excluded in all patients by coronary computed tomographic angiography.ResultsAll subjects had normal left ventricular (LV) ejection and LV mass index, with no LGE. Myocardial perfusion reserve index (MPRI) was lower in T2DM than in controls (1.60 ± 0.44 vs 2.01 ± 0.42; p = 0.008). There was no difference in rest native T1 values (p = 0.59). During adenosine stress, T1 values increased significantly in both T2DM patients (from 1196 ± 32 ms to 1244 ± 44 ms, p < 0.001) and controls (from 1194 ± 26 ms to 1273 ± 44 ms, p < 0.001). T2DM patients showed blunted relative stress non-contrast T1 response (T2DM: ΔT1 = 4.1 ± 2.9% vs. controls: ΔT1 = 6.6 ± 2.6%, p = 0.007) due to a blunted maximal T1 during adenosine stress (T2DM 1244 ± 44 ms vs. controls 1273 ± 44 ms, p = 0.045).ConclusionsPatients with well controlled T2DM, even in the absence of arterial hypertension and significant CAD, exhibit blunted maximal non-contrast T1 response during adenosine vasodilatory stress, likely reflecting coronary microvascular dysfunction. Adenosine stress and rest T1 mapping can detect subclinical abnormalities of the coronary microvasculature, without the need for gadolinium contrast agents. CMR may identify early features of the diabetic heart phenotype and subclinical cardiac risk markers in patients with T2DM, providing an opportunity for early therapeutic intervention.

Synthetic hematocrit derived from the longitudinal relaxation of blood can lead to clinically significant errors in measurement of extracellular volume fraction in pediatric and young adult patients

BackgroundExtracellular volume fraction (ECV) is altered in pathological cardiac remodeling and predicts death and arrhythmia. ECV can be quantified using cardiovascular magnetic resonance (CMR) T1 mapping but calculation requires a measured hematocrit (Hct). The longitudinal relaxation of blood has been used in adults to generate a synthetic Hct (estimate of true Hct) but has not been validated in pediatric populations.MethodsOne hundred fourteen children and young adults underwent a total of 163 CMRs with T1 mapping. The majority of subjects had a measured Hct the same day (N = 146). Native and post-contrast T1 were determined in blood pool, septum, and free wall of mid-LV, avoiding areas of late gadolinium enhancement. Synthetic Hct and ECV were calculated and intraclass correlation coefficient (ICC) and linear regression were used to compare measured and synthetic values.ResultsThe mean age was 16.4 ± 6.4 years and mean left ventricular ejection fraction was 59% ± 9%. The mean measured Hct was 41.8 ± 3.0% compared to the mean synthetic Hct of 43.2% ± 2.9% (p < 0.001, ICC 0.46 [0.27, 0.52]) with the previously published model and 41.8% ± 1.4% (p < 0.001, ICC 0.28 [0.13, 0. 42]) with the locally-derived model. Mean measured mid-free wall ECV was 30.5% ± 4.8% and mean synthetic mid-free wall ECV of local model was 29.7% ± 4.6% (p < 0.001, ICC 0.93 [0.91, 0.95]). Correlations were not affected by heart rate and did not significantly differ in subpopulation analysis. While the ICC was strong, differences between measured and synthetic ECV ranged from −8.4% to 4.3% in the septum and −12.6% to 15.8% in the free wall. Using our laboratory’s normal cut-off of 28.5%, 59 patients (37%) were miscategorized (53 false negatives, 6 false positives) with published model ECV. The local model had 37 miscategorizations (20 false negatives, 17 false positives), significantly fewer but still a substantial number (23%).ConclusionsOur data suggest that use of synthetic Hct for the calculation of ECV results in miscategorization of individual patients. This difference may be less significant once synthetic ECV is calculated and averaged over a large research cohort, making it potentially useful as a research tool. However, we recommend formal measurement of Hct in children and young adults for clinical CMRs.

T1 mapping cardiovascular magnetic resonance imaging to detect myocarditis—Impact of slice orientation on the diagnostic performance

BackgroundT1 mapping is a promising diagnostic tool to improve the diagnostic accuracy of cardiovascular magnetic resonance (CMR) in patients with suspected myocarditis. However, there are currently no data on the potential influence of slice orientation on the diagnostic performance of CMR. Thus, we compared the diagnostic performance of global myocardial T1 and extracellular volume (ECV) values to differentiate patients with myocarditis from healthy individuals between different slice orientations. MethodsThis study included 48 patients with clinically defined myocarditis and 13 healthy controls who underwent CMR at 1.5T. A modified Look-Locker inversion-recovery (MOLLI) sequence was used for T1 mapping before and 15min after administration of 0.075mmol/kg Gadolinium-BOPTA. T1 mapping was performed on three short and on three long axes slices, respectively. Native T1, post-contrast T1 and extracellular volume (ECV) −BOPTA maps were calculated using a dedicated plug-in written for the OsiriX software and compared between the mean value of three short-axes slices (3SAX), the central short-axis (1SAX), the mean value of three long-axes slices (3LAX), the four-chamber view (4CH), the three-chamber view (3CH) and the two-chamber view (2CH). ResultsThere were significantly lower native T1 values on 3LAX (1081ms (1037–1131ms)) compared to 3SAX (1107ms (1069–1143ms), p=0.0022) in patients with myocarditis, but not in controls (1026ms (1009–1059ms) vs. 1039ms (1023–1055ms), p=0.2719). The areas under the curve (AUC) to discriminate between myocarditis and healthy controls by native myocardial T1 were 0.85 (p<0.0001) on 3SAX, 0.85 (p<0.0001) on 1SAX, 0.76 (p=0.0002) on 3LAX, 0.70 (p=0.0075) on 4CH, 0.72 (p=0.0020) on 3CH and 0.75 (p=0.0003) on 2CH. The AUCs for ECV-BOPTA were 0.83 (p<0.0001) on 3 SAX, 0.82 (p<0.0001) on 1SAX, 0.77 (p=0.0005) on 3LAX, 0.71 (p=0.0079) on 4CH, 0.69 (p=0.0371) on 3CH and 0.75 (p=0.0006) on 2CH. ConclusionNative T1 and ECV-BOPTA on short axes slices provide a better diagnostic performance in myocarditis than long axes slices since long axes slices seem to underestimate native myocardial T1 in myocarditis. T1 mapping in suspected myocarditis can be restricted to a single mid-ventricular short-axis slice without a significant loss in diagnostic performance.

Anthracycline-Associated T1 Mapping Characteristics Are Elevated Independent of the Presence of Cardiovascular Comorbidities in Cancer Survivors.

Cardiovascular magnetic resonance T1 mapping characteristics are elevated in adult cancer survivors; however, it remains unknown whether these elevations are related to age or presence of coincident cardiovascular comorbidities. We performed blinded cardiovascular magnetic resonance analyses of left ventricular T1 and extracellular volume (ECV) fraction in 327 individuals (65% women, aged 64±12 years). Thirty-seven individuals had breast cancer or a hematologic malignancy but had not yet initiated their treatment, and 54 cancer survivors who received either anthracycline-based (n=37) or nonanthracycline-based (n=17) chemotherapy 2.8±1.3 years earlier were compared with 236 cancer-free participants. Multivariable analyses were performed to determine the association between T1/ECV measures and variables associated with myocardial fibrosis. Age-adjusted native T1 was elevated pre- (1058±7 ms) and post- (1040±7 ms) receipt of anthracycline chemotherapy versus comparators (965±3 ms; P<0.0001 for both). Age-adjusted ECV, a marker of myocardial fibrosis, was elevated in anthracycline-treated cancer participants (30.4±0.7%) compared with either pretreatment cancer (27.8±0.7%; P<0.01) or cancer-free comparators (26.9±0.2%; P<0.0001). T1 and ECV of nonanthracycline survivors were no different than pretreatment survivors (P=0.17 and P=0.16, respectively). Native T1 and ECV remained elevated in cancer survivors after accounting for demographics (including age), myocardial fibrosis risk factors, and left ventricular ejection fraction or myocardial mass index (P<0.0001 for all). Three years after anthracycline-based chemotherapy, elevations in myocardial T1 and ECV occur independent of underlying cancer or cardiovascular comorbidities, suggesting that imaging biomarkers of interstitial fibrosis in cancer survivors are related to prior receipt of a potentially cardiotoxic cancer treatment regimen.

T1 and T2 mapping cardiovascular magnetic resonance to monitor the course of myocarditis

T1 and T2 mapping cardiovascular magnetic resonance to monitor the course of myocarditis

Quantification of the myocardial partition coefficient for intravenous iron (ferric carboxymaltose) using T1 mapping cardiovascular magnetic resonance

Quantification of the myocardial partition coefficient for intravenous iron (ferric carboxymaltose) using T1 mapping cardiovascular magnetic resonance

Coronary microvascular function and myocardial fibrosis in women with angina pectoris and no obstructive coronary artery disease: the iPOWER study

BackgroundEven in absence of obstructive coronary artery disease women with angina pectoris have a poor prognosis possibly due to coronary microvascular disease. Coronary microvascular disease can be assessed by transthoracic Doppler echocardiography measuring coronary flow velocity reserve (CFVR) and by positron emission tomography measuring myocardial blood flow reserve (MBFR). Diffuse myocardial fibrosis can be assessed by cardiovascular magnetic resonance (CMR) T1 mapping. We hypothesized that coronary microvascular disease is associated with diffuse myocardial fibrosis.MethodsWomen with angina, a clinically indicated coronary angiogram with <50 % stenosis and no diabetes were included. CFVR was measured using dipyridamole (0.84 mg/kg) and MBFR using adenosine (0.84 mg/kg). Focal fibrosis was assessed by 1.5 T CMR late gadolinium enhancement (0.1 mmol/kg) and diffuse myocardial fibrosis by T1 mapping using a modified Look-Locker pulse sequence measuring T1 and extracellular volume fraction (ECV).ResultsCFVR and CMR were performed in 64 women, mean (SD) age 62.5 (8.3) years. MBFR was performed in a subgroup of 54 (84 %) of these women. Mean native T1 was 1023 (86) and ECV (%) was 33.7 (3.5); none had focal fibrosis. Median (IQR) CFVR was 2.3 (1.9; 2.7), 23 (36 %) had CFVR < 2 indicating coronary microvascular disease, and median MBFR was 2.7 (2.2; 3.0) and 19 (35 %) had a MBFR value below 2.5. No significant correlations were found between CFVR and ECV or native T1 (R2 = 0.02; p = 0.27 and R2 = 0.004; p = 0.61, respectively). There were also no correlations between MBFR and ECV or native T1 (R2 = 0.1; p = 0.13 and R2 = 0.004, p = 0.64, respectively). CFVR and MBFR were correlated to hypertension and heart rate.ConclusionIn women with angina and no obstructive coronary artery disease we found no association between measures of coronary microvascular disease and myocardial fibrosis, suggesting that myocardial ischemia induced by coronary microvascular disease does not elicit myocardial fibrosis in this population. The examined parameters seem to provide independent information about myocardial and coronary disease.

Global and regional extracellular volume and myocardial circumferential strain correlate significantly in a heterogeneous patient population

Background Myocardial extracellular volume (ECV) quantification by cardiovascular magnetic resonance (CMR) T1 mapping technique has shown great promises in detecting diffuse fibrosis and interstitial diseases of the myocardium. In hypertensive and left ventricle hypertrophy (LVH) patients, increased ECV has been found to be associated with impaired myocardial strain, which is an early indicator of cardiac dysfunction. We hypothesized that in a heterogeneous patient population, ECV was significantly associated with myocardial strain, on the global and the more localized segmental bases.

Abstract 10114: Cardiovascular Magnetic Resonance Measurement of Myocardial Extracellular Volume by T1 Mapping Differentiates Athlete's Heart From Hypertrophic Cardiomyopathy

Introduction: Athletes who train regularly can develop left ventricular (LV) hypertrophy, which can be difficult to differentiate from hypertrophic cardiomyopathy (HCM), the leading cause of sudden cardiac death in young athletes. Cardiovascular magnetic resonance (CMR) T1 and extracellular volume (ECV) mapping provide quantitative assessment of myocardial composition. Hypothesis: ECV can differentiate athletic from pathological remodelling. Methods: 35 athletes, 25 HCM patients and 35 volunteers underwent 3.0T CMR protocol including 5b(3s)3b Modified Look-Locker Inversion (MOLLI) T1 maps before and 15 minutes after administration of 0.15mmol/kg intravenous gadobutrol. Native T1 and ECV were measured for each subject and each segment of the American Heart Association model. Results: Native T1 and ECV were both significantly lower in athletes than HCM (1182.8±38.1ms vs 1264.6±50.3ms, P&lt;0.001 and 23.2±2.9% vs 32.3±5.9%, P&lt;0.001 respectively). On receiver operator curve analysis the area under the curve (AUC) to differentiate HCM from athlete for native T1 was 0.91 and ECV 0.95. The AUC to differentiate indeterminate 8-15mm thick segments (Figure) were native T1 0.83, ECV 0.92 and segment thickness 0.80 (P&lt;0.001 for all). The diagnostic accuracy of ECV was superior to native T1 and segment thickness (P=0.001 for both). The optimal cut-off to diagnose HCM in an indeterminate segment was ECV&gt;24.7% (sensitivity 91.7% &amp; specificity 83.2%) and native T1&gt;1226ms (sensitivity 60.0% &amp; specificity 96.7%). Conclusions: ECV measurement by CMR is able to distinguish HCM and athletic remodelling with high diagnostic accuracy and has a potential role in the exclusion of HCM in athletes presenting with left ventricular hypertrophy. Figure: ROC curves for segmental wall thickness (mm), native T1 (ms) and ECV (%) for the detection of HCM against athletes in intermediate wall thickness segments (8-15mm thick). AUCs were 0.80, 0.83, and 0.92 respectively (P&lt;0.001 for all).

Prognostic significance of myocardial extracellular volume fraction in nonischaemic dilated cardiomyopathy.

In nonischaemic dilated cardiomyopathy (NICM), replacement myocardial fibrosis as detected by late gadolinium enhancement (LGE) at cardiovascular magnetic resonance (CMR) is associated with poor prognosis. We investigated the as-yet unexplored prognostic significance of interstitial fibrosis in NICM, using T1-mapping CMR. Eighty-nine NICM patients (63 men, age 59 ± 14 years) with left ventricular systolic dysfunction (ejection fraction 41 ± 13%) underwent comprehensive clinical and CMR evaluation, with extracellular volume fraction (ECV) estimation from pre and postcontrast T1 mapping. Fifteen healthy individuals (11 men, mean age 52 ± 11 years) were used as controls. The end-point was a composite of cardiovascular death, hospitalization for heart failure and appropriate defibrillator intervention. Myocardial ECV was higher in NICM patients (0.31 ± 0.05) than controls (0.25 ± 0.04, P < 0.01). In NICM patients, myocardial ECV correlated with left ventricular ejection fraction (R = 0.13), LGE extent (R = 0.17), Doppler E/E' (R = 0.17) and ventricular tachycardias (R = 0.21) at 24-h ECG monitoring (P < 0.05 for all). During a median follow-up of 24 months (interquartile range 12-42 months), 12 events occurred and higher myocardium ECV was independently associated with the occurrence of the composite end-point (P < 0.01). In NICM patients, myocardial ECV was increased compared with normal individuals, likely reflecting extracellular matrix remodelling and collagen deposition, and resulted an independent prognostic predictor beyond all other conventional clinical, electrocardiographic and echocardiographic parameters.

PP.08.21

Objective: The new cardiovascular magnetic resonance (CMR) T1 mapping sequences can be applied to quantify diffuse myocardial fibrosis. Also, new CMR analysis softwares allow for the accurate and reproducible measurement of myocardial strain. We aimed to use these two new developments in a pilot study in order to assess the association between presence of diffuse fibrosis and changes in myocardial strain. Design and method: 12 hypertensive patients (HT, 52 ± 7yrs, 10 males) with preserved ejection fraction and 12 controls (NT, 44 ± 10yrs, 8 males) underwent a CMR protocol at 3T that included black blood morphological sequences, cine sequences in the 2,3 and 4-chamber views as well as short axis series with typically 40 phases for each image acquisition, T1-mapping with two MOLLI acquisitions (3–3–5), before and 15 min after administration of a bolus of gadolinium-DTPA (0.1 mM/kg), and late gadolinium sequences in the same views as the cine sequences. All the scans were eventually analysed by two experienced observers with a dedicated software to obtain left ventricular volumes, ejection fraction and mass, precontrast myocardial T1 values, gadolinium partition coefficient (GPC) and extracellular volume fraction (ECV), a measure of diffuse myocardial fibrosis. Also, global longitudinal and radial myocardial strain and strain rate, as well as epicardium-endocardium strain gradient were measured. Results: All subjects had preserved systolic function and results are shown on the table. There was a trend towards increased ECV in HT though it did not reach statistical significance.Global londitudinal and radial strain (GLS, GRS), longitudinal strain rate (GLSR) and precontrast T1 were all lower in HT, while radial strain gradient between subendocardium and subepicardium (GRS endo-epi) was increased in HT. There was a significant inverse correlation of GLS and GRS with ECV, and of radial strain rate with ECV (all p < 0.05).Conclusions: In this pilot study we have found that there is an inverse correlation between global strain, a sensitive indicator of regional contractility, and myocardial extracellular volume fraction, a marker of diffuse fibrosis. This finding may have implications for early diagnosis of target organ damage in hypertensive patients.

125 Myocardial Extracellular Volume Estimation by Cardiovascular Magnetic Resonance Predicts Functional Recovery Following Acute Myocardial Infarction

Background The transmural extent of myocardial infarction (MI) assessed by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is a reference standard for prediction of functional recovery. In acute MI (AMI), myocardial oedema and effects of reperfusion therapy reduce the predictive accuracy of LGE. LGE assesses tissue dichotomously as “viable” or “non-viable”, but does not consider severity of tissue damage within the hyperenhanced infarct zone. Extracellular volume (ECV) estimation, using native and post-contrast T1 mapping CMR, allows for quantitative assessment of severity of myocardial damage. We aimed to assess if CMR measurement of infarct ECV offers additional predictive value over LGE extent for contractile recovery in reperfused AMI. Methods 35 patients with first ST-segment elevation AMI treated by primary percutaneous coronary intervention underwent acute (day 2) and convalescent (3 months) CMR at 3 Tesla. Cine imaging, tissue tagging, modified Look-Locker inversion T1 mapping (3–3–5 acquisition with 3x R-R interval recovery epochs) natively and 15 min post gadolinium-contrast administration and LGE imaging at 20 min were performed. The ability of acute infarct ECV and acute transmural extent of LGE to predict convalescent wall motion, ejection fraction (EF) and strain were compared. A per-patient analysis was performed using a region of interest corresponding to the core of the infarct, excluding any microvascular obstruction (MO). Segmental analysis was also performed and evaluated using a multilevel linear mixed-effects model to account for non-independence of segmental data. Results Per-patient, ECV and transmural extent of LGE correlated with convalescent wall motion score (r = 0.43, p Conclusions Acute infarct ECV in reperfused AMI predicts LV functional recovery, and is both independent of and more accurate than transmural extent by LGE. There is clinical utility for ECV mapping post-AMI.