Short-axis Slices Research Articles

Influence of cardiac phase on myocardial native T1 values by a segmental approach

Abstract Funding Acknowledgements Type of funding sources: None. Background. Native T1 values are usually assessed in the end-diastole to minimize motion artifacts while the systolic data acquisition offers the advantage of a thicker myocardium, with reduced partial-volume effects. Higher myocardial T1 values have been detected in diastole at both 1.5T and 3T but the dependence of this difference on myocardial segments or gender has not been fully explored. Aim. We provided a systematic comparison of myocardial native T1 values in diastole and systole, by considering separately myocardial segments and dividing males and females. Methods. Sixty-one healthy subjects (46.0 ± 14.1 years, 32 males) underwent CMR at 1.5T (Signa Artist; GE Healthcare). Three short-axis slices of the left ventricle acquired in diastole and systole using a Modified Look–Locker Inversion Recovery sequence. Image analysis was performed with a commercially available software package. T1 value was assessed in all 16 myocardial segments and global value was the mean. Results. Table 1 shows the comparison between T1 values calculated from maps obtained in diastole and systole. Systolic T1 values were significantly lower in the basal anterolateral segment, in all medium segments except for the medium inferior segment, and in all apical segments. The percentage difference between diastolic and systolic T1 values was considered to compensate for the higher T1 values in females, and a significantly higher value was detected in females for the majority of medium segments, for all apical segments, and for the global value. Conclusion. The diastolic-systolic discrepancy was more pronounced for the females and at the apical level, supporting the hypothesis that, besides the physiologic variations in myocardial blood volume during the cardiac cycle, the partial volume-effect may be a strong additional contributing factor. Native T1 values should be obtained always in the same cardiac phase to avoid a potential bias in the discrimination between healthy and pathologically affected myocardium.

Native T1 mapping and extracellular volume fraction for differentiation of myocardial diseases from normal CMR controls in routine clinical practice

BackgroundThis study aimed to determine native T1 and extracellular volume fraction (ECV) in distinct types of myocardial disease, including amyloidosis, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), myocarditis and coronary artery disease (CAD), compared to controls.Methods We retrospectively enrolled patients with distinct types of myocardial disease, CAD patients, and control group (no known heart disease and negative CMR study) who underwent 3.0 Tesla CMR with routine T1 mapping. The region of interest (ROI) was drawn in the myocardium of the mid left ventricular (LV) short axis slice and at the interventricular septum of mid LV slice. ECV was calculated by actual hematocrit (Hct) and synthetic Hct. T1 mapping and ECV was compared between myocardial disease and controls, and between CAD and controls. Diagnostic yield and cut-off values were assessed.ResultsA total of 1188 patients were enrolled. The average T1 values in the control group were 1304 ± 42 ms at septum, and 1294 ± 37 ms at mid LV slice. The average T1 values in patients with myocardial disease and CAD were significantly higher than in controls (1441 ± 72, 1349 ± 59, 1345 ± 59, 1355 ± 56, and 1328 ± 54 ms for septum of amyloidosis, DCM, HCM, myocarditis, and CAD). Native T1 of the mid LV level and ECV at septum and mid LV with actual and synthetic Hct of patients with myocardial disease or CAD were significantly higher than in controls.ConclusionsAlthough native T1 and ECV of patients with cardiomyopathy and CAD were significantly higher than controls, the values overlapped. The greatest clinical utilization was found for the amyloidosis group.

Global and Regional Test-Retest Reproducibility of Native T1 and T2 Mapping in Cardiac Magnetic Resonance Imaging.

Mapping of T1 and T2 relaxation times in cardiac MRI is an invaluable tool for the diagnosis and risk stratification of a wide spectrum of cardiac diseases. To investigate the global and regional reproducibility of native T1 and T2 mapping and to analyze the influence of demographic factors, physiological parameters, slice position, and myocardial regions on reproducibility. Prospective single-center cohort-study. Fifty healthy volunteers (29 female, 21 male) with a mean age of 39.4 ± 13.7 years. Each volunteer was investigated twice at 1.5 T using a modified look-locker inversion-recovery (MOLLI) sequence (T1 mapping) and a T2-prepared steady-state free precession (SSFP) sequence (T2 mapping). Global T1 and T2 values were quantified for the entire left ventricle in three short-axis slices. Regional T1 and T2 values were measured for each myocardial segment and for myocardial segments grouped by slice position and anatomical region. Test-retest reproducibility was assessed using intraclass correlation coefficient (ICC) and Bland-Altman statistics. A P value < 0.05 was considered statistically significant. Reproducibility was good for global T1 values (ICC 0.88) and excellent for global T2 values (ICC 0.91). Reproducibility of T1 values was excellent (ICC 0.91) for midventricular slice and good for apical (ICC 0.86) and basal slice (ICC 0.81). Reproducibility of T1 mapping values was highest in the septum (ICC 0.90) compared to the anterior (0.81), lateral (0.86), and inferior (0.86) wall. For T2 mapping, reproducibility was good for all slice positions (ICC 0.86 for midventricular, 0.83 for basal, and 0.80 for apical slice). Reproducibility of T2 mapping was significantly lower for the inferior wall (ICC 0.58) than for septum (0.89), anterior (0.85), and lateral (0.87) wall. Native T1 and T2 mapping has good to excellent reproducibility with significant regional differences. 2 TECHNICAL EFFICACY: Stage 2.

New approach for quantification of left ventricular function from low-dose gated bloodpool SPECT: Validation and comparison with conventional methods in patients

BackgroundPlanar equilibrium radionuclide angiocardiography (ERNA) has been used as the gold standard for assessment of left ventricular (LV) function for over three decades. However, this imaging modality has recently gained less favor due to growing concerns about radiation exposure. We developed a novel approach that involves integrating short axis slices of gated bloodpool SPECT for quantification of LV function with improved signal-to-noise ratio and reduced radioactive dose while maintaining image quality and quantitative precision. MethodsTwenty patients referred for ERNA underwent standard in vitro 99mTc-labeling of red blood cells (RBC), and were initially imaged following a low-dose (~ 8 mCi) injection using a dedicated cardiac SPECT camera, and then had planar imaging following a high-dose (~ 25 mCi) injection. Four different quantification methods were utilized to assess the LV function and were compared for quantitative precision and inter-observer reproducibility of the quantitative assessments. ResultsThe Yale method resulted in the most consistent assessment of LV function compared with the gold standard high-dose ERNA method, along with excellent inter-observer reproducibility. ConclusionsThe new low-dose 99mTc-RBC imaging method provides precise quantification of LV function with a greater than 67% reduction in dose and may potentially improve assessment of regional function.

Fat-saturated dark-blood cardiac T2 mapping in a single breath-hold

PurposeConventional cardiac T2 mapping suffers from the partial-voluming effect in the endocardium and epicardium due to the co-presence of intra-cavity blood and epicardial fat. The aim of the study is to develop a novel single-breath-hold Fat-Saturated Dark-Blood (FSDB) cardiac T2-mapping technique to mitigate the partial-voluming and improve T2 accuracy. MethodsThe proposed FSDB T2-mapping technique combines T2-prepared bSSFP, a novel use of double inversion-recovery with heart-rate-adaptive TI, and spectrally-selective fat saturation to mitigate partial-voluming from both the blood and fat. FSDB T2 mapping was compared to conventional T2 mapping via simulations, phantom imaging, healthy-subject imaging (n = 8), and patient imaging (n = 7). In the healthy subjects, a high-resolution coplanar anatomical imaging was performed to provide a gold standard for segmentation of endocardium and epicardium. T2 maps were registered to the gold standard image to evaluate any inter-layer T2 difference, which is a surrogate for partial-voluming. ResultsSimulations and phantom imaging showed that FSDB T2 mapping was accurate in a range of heartrates, off-resonance, and T2 values, and blood/fat reasonably nulled in a range of heartrates. In healthy subjects, FSDB T2 mapping showed similar T2 values over different myocardial layers in all 3 short-axis slices (e.g. basal epicardial/mid-wall/endocardial T2 = 42 ± 2 ms/41 ± 1 ms/42 ± 1 ms), whereas conventional T2 mapping showed considerably increased T2 in the endocardium and epicardium (e.g. basal epicardial/mid-wall/endocardial T2 = 48 ± 3 ms/43 ± 1 ms/49 ± 3 ms). The homogeneous T2 in the FSDB T2 mapping increased the apparent LV-wall thickness by 25–41% compared with the conventional method. ConclusionsThe proposed technique improves accuracy of myocardial T2 mapping against partial-voluming associated with both fat and blood, facilitating a multi-layer T2 evaluation of the myocardium. This technique may improve utility of cardiac T2 mapping in diseases affecting the endocardium and epicardium, and in patients with a small heart.

A novel deep-learning-based approach for automatic reorientation of 3D cardiac SPECT images.

Reconstructed transaxial cardiac SPECT images need to be reoriented into standard short-axis slices for subsequent accurate processing and analysis. We proposed a novel deep-learning-based method for fully automatic reorientation of cardiac SPECT images and evaluated its performance on data from two clinical centers. We used a convolutional neural network to predict the 6 rigid-body transformation parameters and a spatial transformation network was then implemented to apply these parameters on the input images for image reorientation. A novel compound loss function which balanced the parametric similarity and penalized discrepancy of the prediction and training dataset was utilized in the training stage. Data from a set of 322 patients underwent data augmentation to 6440 groups of images for the network training, and a dataset of 52 patients from the same center and 23 patients from another center were used for evaluation. Similarity of the 6 parameters was analyzed between the proposed and the manual methods. Polar maps were generated from the output images and the averaged count values of the 17 segments were computed from polar maps to evaluate the quantitative accuracy of the proposed method. All the testing patients achieved automatic reorientation successfully. Linear regression results showed the 6 predicted rigid parameters and the average count value of the 17 segments having good agreement with the reference manual method. No significant difference by paired t-test was noticed between the rigid parameters of our method and the manual method (p > 0.05). Average count values of the 17 segments show a smaller difference of the proposed and manual methods than those between the existing and manual methods. The results strongly indicate the feasibility of our method in accurate automatic cardiac SPECT reorientation. This deep-learning-based reorientation method has great promise for clinical application and warrants further investigation.

Impact of Wideband Late Gadolinium Enhancement Cardiac Magnetic Resonance Imaging on Device-Related Artifacts in Different Implantable Cardioverter-Defibrillator Types.

Late gadolinium enhancement (LGE) imaging in patients with implantable cardioverter-defibrillators (ICD) is limited by device-related artifacts (DRA). The use of wideband (WB) LGE protocols improves LGE images, but their efficacy with different ICD types is not well known. To assess the effects of WB LGE imaging on DRA in different non-MR conditional ICD subtypes. Retrospective. A total of 113 patients undergoing cardiac magnetic resonance imaging with three ICD subtypes: transvenous (TV-ICD, N=48), cardiac-resynchronization therapy device (CRT-D, N=48), and subcutaneous (S-ICD, N=17). 5 T scanner, standard LGE, and WB LGE imaging with a phase-sensitive inversion recovery segmented gradient echo sequence. DRA burden was defined as the number of artifact-positive short-axis LGE slices as percentage of the total number of short-axis slices covering the left ventricle from based to apex, and was determined for WB and standard LGE studies for each patient. Additionally, artifact area on each slice was quantified. Shapiro-Wilks, Kruskal-Wallis analysis of variance, Dunn tests with Bonferroni correction, and Mann-Whitney U-test. In patients with TV-ICD, DRA burden was significantly reduced and nearly eliminated with WB LGE compared to standard LGE imaging (median [interquartile range]: 0 [0-7]% vs. 18 [0-50]%, P< 0.05), but WB imaging had less of an impact on DRA in the CRT-D (8 [0-23]% vs. 16 [0-45]%, p=0.12) and S-ICD (60 [15-71]% vs. 67 [50-92]%, P= 0.09) patients. Residual DRA was significantly greater (P< 0.05) for S-ICD compared to other device types with WB LGE imaging, despite the generators of all three ICD types having similar proximity to the heart. The area of S-ICD associated DRA was smaller with WB LGE (P< 0.001) than with standard LGE imaging and the artifacts had different characteristics (dark signal void instead of a bright hyperenhancement artifact). Although WB LGE imaging reduced the burden of DRA caused by S-ICD, the residual artifact was greater than that observed with TV-ICD and CRT-D devices. Further developments are needed to better resolve S-ICD artifacts. 1 TECHNICAL EFFICACY: STAGE: 5.

A review of approaches investigated for right ventricular segmentation using short‐axis cardiac MRI

The right ventricular assessment is crucial to heart disease diagnosis. Unfortunately, its segmentation is quite challenging due to its intricate shape, ill-defined thin edges, large variability among patients, and pathologies. Besides, it is a very laborious and time-consuming task to be done manually. Therefore, automated segmentation techniques are very suitable to reduce the strain on the expert. Here, it is attempted to review the taxonomy of the current RV segmentation approaches adopted to handle the afore-mentioned issues. Enhanced by our expert's interpretation, the results of over forty research papers were evaluated based on several metrics such as the dice metric and the Hausdorff distance. Synthetic tables and charts were also used to discuss the reviewed approaches. The following study shows that none of the existing methods has proved accurate enough to meet all the RV challenging issues. Many misestimated results were reported for several cases. Eventually, global guidance is outlined, which supports combining different methods to enhance the expected results during the MRI short-axis slice processing.

T2-based area-at-risk and edema are influenced by ischemic duration in acute myocardial infarction

The purpose of our study was to assess whether T2 MRI identifies the infarcted myocardium or the true area-at-risk (AAR) and whether edema is present in the salvageable region following acute myocardial infarction (MI). The study involved a porcine model of MI with a coronary occlusion model of either 60 min or 90 min. Imaging was performed on a 3T MRI pre-occlusion and at day 3 post-MI. Prior-MI, myocardial perfusion territory (MPT) maps were obtained under MRI via direct intracoronary injection of contrast agent. Post-MI, edema extent was quantified by T2 mapping while infarction and microvascular obstruction (MVO) were assessed by late gadolinium enhancement (LGE). Anatomically registered short-axis slices were analyzed for MPT, T2-AAR and infarct areas and T2 relaxation values. Animals were divided into groups with (MVO+) and without MVO (MVO-). T2-AAR area was significantly greater than infarct area in both groups. In the MVO+ group, T2-AAR and MPT were comparable and highly correlated, whereas, in the MVO- group, T2-AAR significantly underestimated MPT without any trend. T2 values in the salvageable myocardium were found to be significantly higher than those in remote myocardium. Our methodology offers the advantage that all images are acquired within the same MRI reference as opposed to complex co-registration with gross pathology. Our study suggests that edema may expand beyond the infarct zone over the entire ischemic bed. T2-AAR may be more clinically relevant than true AAR by perfusion territory since it identifies the “salvageable” myocardium.

Myofiber strain in healthy humans using DENSE and cDTI.

Myofiber strain, Eff , is a mechanistically relevant metric of cardiac cell shortening and is expected to be spatially uniform in healthy populations, making it a prime candidate for the evaluation of local cardiomyocyte contractility. In this study, a new, efficient pipeline was proposed to combine microstructural cDTI and functional DENSE data in order to estimate Eff in vivo. Thirty healthy volunteers were scanned with three long-axis (LA) and three short-axis (SA) DENSE slices using 2D displacement encoding and one SA slice of cDTI. The total acquisition time was 11 minutes ± 3 minutes across volunteers. The pipeline first generates 3D SA displacements from all DENSE slices which are then combined with cDTI data to generate a cine of myofiber orientations and compute Eff . The precision of the post-processing pipeline was assessed using a computational phantom study. Transmural myofiber strain was compared to circumferential strain, Ecc , in healthy volunteers using a Wilcoxon sign rank test. In vivo, computed Eff was found uniform transmurally compared to Ecc (-0.14[-0.15, -0.12] vs -0.18 [-0.20, -0.16], P < .001, -0.14 [-0.16, -0.12] vs -0.16 [-0.17, -0.13], P < .001 and -0.14 [-0.16, -0.12] vs Ecc_C = -0.14 [-0.15, -0.11], P = .002, Eff_C vs Ecc_C in the endo, mid, and epi layers, respectively). We demonstrate that it is possible to measure in vivo myofiber strain in a healthy human population in 10 minutes per subject. Myofiber strain was observed to be spatially uniform in healthy volunteers making it a potential biomarker for the evaluation of local cardiomyocyte contractility in assessing cardiovascular dysfunction.

Determination of scar area using native and post contrast T1 mapping: a validation study

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Goethe University Hospital Introduction Late gadolinium enhancement (LGE) with Full Width Half Maximum (FWHM) is the standard imaging method for the measurement of the scar area in ischemic heart disease, a major determinant of adverse outcome. T1 mapping techniques have become increasingly applied in everyday clinical practice. Agreement in area quantification between T1 mapping and LGE for the scar extent has not been systematically assessed. Purpose This study aims to ascertain concordance between the area determined by native and post contrast T1 mapping against LGE to determine scar area in patients with a prior myocardial infarction. It also examines intra and inter-observer reproducibility for these two methods. Methods Subendocardial scar was evaluated in 132 patients with ischemic heart disease using LGE, native and post contrast T1 mapping in 3 short axis slices. Native and postcontrast T1 mapping was performed using GoetheCVI®MOLLI sequence (Gadovist® 0.1mmol/kg). FWHM method was applied for LGE and compared with the manually delineated area of scar in native and postcontrast T1 mapping acquisitions within the identical slices. The presence of the scar was defined as LGE &amp;gt;3% of the myocardial mass. Bland-Altman methods were employed to assess concordance between techniques and reproducibly between observers. Results In comparison to LGE, area measurements in native T1 acquisitions underestimated infarct size (9,1% vs 12,6%, p = 0.01), while postcontrast T1 overestimated it (19,4% vs 12,6%, p &amp;lt; 0.001). The disparity between the measurements was accentuated with larger scar areas (Figure 1). Intraobserver reproducibility (native T1: intra/inter MD ± SD, CoV, postcontrast T1: intra/inter) was similar with both methods, whereas interobserver variability for native T1 mapping acquisition was worse. Conclusions We demonstrate that measurements of the area of myocardial scar by T1 mapping acquisitions yield considerably different results in comparison to the standard LGE-based FWHM method. High observer agreement indicates that these differences are genuinely related to the type of the underlying acquisition and the differences in detected signal. The approaches are not interchangeable. However, the importance of these results for predicting patient outcome is yet to be elucidated. Nonetheless, these results were consistent in the inter and intraobserver analysis for post contrast T1 mapping, although native T1 mapping failed to show similar consistency. Figure 1: Bland-Altmann plot of differences (mean ± upper and lower limit of agreement-LOA) in scar area extent (percentage) between LGE and native T1 mapping (A), LGE and post contrast T1 mapping (B). The difference increases linearly for larger scar areas when using post contrast mapping, which does not apply for native mapping. Abstract Figure 1

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

Abstract 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 &amp;gt; 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 &amp;lt; 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

Novel dark-blood versus conventional bright-blood late gadolinium enhancement CMR: A pilot study comparing impact on myocardial ischaemic burden

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Background In patients with coronary artery disease (CAD), increasing myocardial ischaemic burden (MIB) is a strong predictor of adverse events. When measured by cardiovascular magnetic resonance (CMR), a MIB ≥12.5% is considered significant and often used as a threshold to guide revascularisation. Ischaemic scar can cause stress perfusion defects which do not represent ischaemia and should be excluded from the MIB calculation. Conventional bright-blood late gadolinium enhancement (LGE) is able to identify ischaemic scar but can suffer from poor scar-to-blood contrast, making accurate assessment of scar volume difficult. Dark-blood LGE methods increase scar-to-blood contrast and improve scar conspicuity which may impact the calculated scar burden and consequently the estimation of MIB when read in conjunction with perfusion images. Purpose To evaluate the impact of dark-blood LGE versus conventional bright-blood LGE on the estimation of MIB in patients with CAD. Methods 37 patients with suspected or known CAD who had evidence of CMR stress perfusion defects and ischaemic scar on LGE imaging were recruited. Patients underwent adenosine stress perfusion imaging followed by dark-blood LGE then conventional bright-blood LGE imaging at 3T. For dark-blood LGE, phase sensitive inversion recovery imaging with a shorter inversion time to null the LV blood-pool was used without any additional magnetization preparation. For each patient, three short-axis LGE slices were selected to match the three perfusion slice locations. Images were anonymised and analysed in random order. Ischaemic scar burden (ISB) was quantified for both LGE methods using a threshold &amp;gt;5 standard deviations above remote myocardium. Perfusion defect burden (PDB) was quantified by manual contouring of perfusion defects. MIB was calculated by subtracting the ISB from the PDB. Results MIB calculated using dark-blood LGE was 19% less compared to bright-blood LGE (15.7 ± 15.2% vs 19.4 ± 15.2%, p &amp;lt; 0.001). There was a strong positive correlation between the two LGE methods (rs = 0.960, p &amp;lt; 0.001, Figure 1A). Bland-Altman analysis revealed a significant fixed bias (mean bias = -3.6%, bias 95% CI: -2.6 to -4.7%, 95% limits of agreement: -9.8 to 2.5%) with no proportional bias (Figure 1B). MIB was calculated ≥12.5% and &amp;lt;12.5% by both LGE methods in 19 (51%) and 12 (32%) patients respectively. In 6 patients (16%), MIB was ≥12.5% using bright-blood LGE and &amp;lt;12.5% using dark-blood LGE (Figure 1A – orange data points). Overall, when used to classify MIB as &amp;lt;12.5% or ≥12.5%, there was only substantial agreement between the two LGE methods (κ=0.67, 95% CI: 0.45 to 0.90). Conclusions The use of dark-blood LGE in conjunction with perfusion imaging results in a lower estimate of MIB compared to conventional bright-blood LGE. This can cause disagreement around the threshold of clinically significant ischaemia which could impact clinical management in patients being considered for coronary revascularisation. Abstract Figure. Linear regression with corresponding B&amp;A

Tissue characteristics of the athlete"s heart: differentiation of physiological and pathological hypertrophy using parametric T1 and T2 mapping

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary Background Intensive physical exercise leads to structural and functional cardiac adaptation termed athlete’s heart. Cardiac magnetic resonance (CMR) has an important role in the differentiation of physiological adaptation and pathological conditions. Beside the precise measurement of the ventricular volumes, mass, and function, it provides tissue specific information. Recently, native T1 mapping technique has been applied as a non-contrast method to detect myocardial fibrosis. Previous studies suggested that native T1 mapping can identify myocardial pathology before other CMR imaging techniques. T2 mapping values are elevated in case of myocardial edema. Purpose The aim of our study was to investigate the differences in CMR characteristics especially the native T1 and T2 mapping values of highly trained healthy athletes, healthy controls and patients with hypertrophic cardiomyopathy (HCM). Methods A total of 43 healthy athletes (water polo, swimming, football, 22 ± 8 training hours/week), 27 non-athlete healthy control and 25 HCM patients were involved in the study. Our inclusion criteria were: age &amp;gt;18 years, in the athlete group &amp;gt;7 training hours per week . We evaluated the left ventricular (LV) end-systolic, end-diastolic (EDVi) and stroke volume (SVi) index, mass index (LVMi), ejection fraction (EF) and maximal end-diastolic wall thickness (EDWT). In a basal short axis slice the native T1 and T2 mapping values were evaluated. Results Athletes had significantly higher LV volumes compared to the control and HCM group (LVEDVi 114 ± 13 vs. 86 ± 11; 84 ± 15 ml/m2, LVSVi 64 ± 7 vs. 51 ± 7; 54 ± 10 ml/m2, respectively, p &amp;lt; 0.0001). HCM patients had the highest LVMi (72 ± 14 g/m2) and EDWT (18 ± 4 mm) compared to athletes and controls, athletes had higher LVMi (60 ± 11 vs. 42 ± 8 g/m2) and EDWT (10 ± 2 vs. 8 ± 1 mm) compared to the controls (p &amp;lt; 0.001). The native T1 mapping values differed significantly in the three groups, athletes had the lowest, HCM patients had the highest T1 values (athletes: 956 ± 19 ms, controls: 971 ± 20 ms, HCM patients: 993 ± 39 ms; p &amp;lt; 0.0001). There was no difference in the T2 mapping values between athletes and controls (44 ± 2 vs. 43 ± 2 ms), HCM patients had higher T2 values (45 ± 2 ms) compared to the other two groups (p &amp;lt; 0.01). Conclusion Intensive and regular training may lead to tissue specific changes of the myocardium. T1 and T2 mapping are potentially useful tools for differentiating between athlete"s heart and patients with hypertrophic cardiomyopathy. Abstract Figure. T1 mapping in HCM and athlete

Comparison of the T2 effects of three T1 mapping sequences of the myocardium at 3T and 1.5T

Abstract Funding Acknowledgements Type of funding sources: None. Purpose To compare the T2 effects of three T1 mapping sequences of the myocardium at 3T and 1.5T. Materials and Methods We measured native T1 values by three T1 mapping sequences (FFM, MPI and LONG) and T2 values of 630 consecutive subjects (patients and healthy volunteers) in a mid-ventricular short axis slice by regions of interest (ROIs) placed conservatively within the septal myocardium. Correlations between myocardial T1 and T2 values were analyzed. Results Native T1 values differed significantly depending on the sequence, with MPI providing consistently higher mean values than FFM and LONG, LONG providing higher mean values than FFM (all p &amp;lt; 0.001). T1 by FFM, MPI and LONG in the total population, disease group, non-ischaemic cardiomyopathy group were all weakly related to T2 at 3T. The correlation coefficient of MPI were the highest in the total population and disease group, but there is no significant difference in correlation coefficients (all p &amp;gt; 0.05). Similarly, T1 by FFM, LONG in the total population, disease group, NICM group were all weakly-moderately related to T2 at 1.5T. In the control group, only T1 by MPI was moderately and positively related to T2(r = 0.469, p = 0.037). In the ischaemic cardiomyopathy group, only T1 by MPI was weakly and positively related to T2 (r = 0.334, p = 0.011). In the stress condition, T1 by FFM and MPI was weakly and positively related to T2 (r = 0.280,0.210, p = 0.001,0.012, respectively). Conclusion The T2 effects existed in three T1 mapping sequences of the myocardium in varying degrees, we should consider the potential bias from T2 when analyzing the abnormal T1 values of myocardium. Abstract Figure.

Real-time cardiovascular magnetic resonance tissue characterisation in patients undergoing transcatheter aortic valve replacement

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (DFG, CRC 1002, D1) Background Myocardial fibrosis is a major determinant of outcome in aortic stenosis (AS). Novel fast real-time (RT) cardiac magnetic resonance (CMR) mapping techniques allow comprehensive quantification of fibrosis but have not yet been compared against standard techniques and histology. Methods Patients with severe AS underwent CMR before (n = 110) and left ventricular (LV) endomyocardial biopsy (n = 46) at transcatheter aortic valve replacement (TAVR). Midventricular short axis (SAX) native, post-contrast T1 and extracellular volume fraction (ECV) maps were generated using commercially available MOLLI (native: 5(3)3, post-contrast: 4(1)3(1)2) and RT single-shot inversion recovery fast low-angle shot (FLASH) with radial undersampling. Focal late gadolinium enhancement was excluded from T1 and ECV regions of interest. ECV and LV mass were used to calculate LV matrix volumes. Variability and agreements were assessed between RT, MOLLI and histology using intraclass correlation coefficients, coefficients of variation and Bland Altman analyses. Results RT and MOLLI derived ECV were similar for midventricular SAX slice coverage (26.2 vs. 26.5, p = 0.073) and septal region of interest (26.2 vs. 26.5, p = 0.216). MOLLI native T1 time was in median 20 ms longer compared to RT (p &amp;lt; 0.001). Agreement between RT and MOLLI was best for ECV (ICC &amp;gt;0.91), excellent for post-contrast T1 times (ICC &amp;gt;0.81) and good for native T1 times (ICC &amp;gt;0.62). Diffuse collagen volume fraction by biopsies was in median 7.8%. ECV (RT r = 0.345, p = 0.039; MOLLI r = 0.40, p = 0.010) and LV matrix volumes (RT r = 0.45, p = 0.005; MOLLI r = 0.43, p = 0.007) were the only parameters associated with histology. Conclusions RT mapping offers fast and sufficient ECV and LV matrix volume calculation in AS. ECV and LV matrix volume represent robust and universally comparable parameters with associations to histologically assessed fibrosis and may emerge as potential targets for clinical decision making.

Myocardial native T1 mapping and cardiac outcomes in thalassemia major

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): The E-MIOT project receives “no-profit support” from industrial sponsorships (Chiesi Farmaceutici S.p.A. and ApoPharma Inc. and Bayer). Background. The T2* cardiovascular magnetic resonance (CMR) is the gold standard for the non invasive detection of myocardial iron overload (MIO). The native myocardial T1 mapping has been proposed as a complementary tool, thanks to its higher sensitivity in presence of small amounts of iron, but no data are available in literature about its clinical impact. Objective To explore the clinical impact of T1 mapping for detecting cardiac complications in thalassemia major (TM). Methods. We considered 146 TM patients (87 females, 38.7 ± 11.1 years) consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia Network. Three parallel short-axis slices of the left ventricle (LV) were acquired with the Modified Look-Locker Inversion recovery (MOLLI) sequence. The native T1 values in all 16 myocardial segments were obtained and the global value was the mean. Results. Twenty-one patients had an history of cardiac complications: 11 heart failure, 8 arrhythmias (7 supraventricular and 1 ventricular), and 2 pulmonary hyperthension. Patients with cardiac complications had significantly lower global heart T1 values (879.3 ± 121.9 ms vs 963.2 ± 98.5 ms; P &amp;lt; 0.0001) (Figure) but comparable T2* values (33.32 ± 11.66 ms vs 37.17 ± 9.15 ms; P = 0.116). Cardiac complications were more frequent in the group of patients with reduced global heart T1 value (&amp;lt;928 ms for males and &amp;lt;989 ms for females) compared to the group with normal global heart T1 value (71.4% vs 39.5%; P = 0.009). Odds ratio (OR) for cardiac complications was 3.8 (95%CI = 1.3-10.9) for patients with reduced global heart T1 value versus patients with normal global heart T1 value. Conclusion We found out a significant association between decreased native global heart T1 values and a history of cardiac complications, suggesting that an early detection of myocardial iron burden by native T1 can support the clinicians in modifing chelation therapy earlier. Abstract Figure.

Capturing complex right ventricular wall motion abnormalities in arrhythmogenic right ventricular cardiomyopathy by combining longitudinal and radial myocardial dynamics in feature-tracking MRI

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): INSERM Liliane Bettencourt doctoral grant Background Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is ass­­ociated with complex spatial and temporal right ventricular (RV) wall motion abnormalities. While cardiac magnetic resonance (CMR) is the gold-standard imaging technique, its diagnosic performance remains suboptimal and additional CMR biomarkers reflecting ARVC pathophysiology are needed. Purpose To evaluate the performance of a CMR feature-tracking (FT)-derived parameter combining both longitudinal and radial RV deformation and motion for the characterization of RV wall motion abnormalities in ARVC. Methods Thirty-nine patients with definite or borderline ARVC (median age 45 years, interquartile range 31–51, 56% males) were compared to 20 healthy controls with comparable age, sex and weight distributions. All subjects had 1.5T CMR including short axis and 4-chamber views steady-state free precession acquisitions. A custom FT software adapted to RV wall segmentation and tracking was used to assess RV wall deformation and motion in the 3 space directions resulting in: 1) global longitudinal strain (GLS) estimated on the 4 chamber view from the RV free wall, 2) basal circumferential strain (BCS) and radial motion fraction (BRMF) estimated as an average of short-axis slices comprised in the RV third basal portion. To capture the complex RV motion in ARCV, a longitudinal to radial strain loop (LRSL) was displayed and its area was calculated. Results The ARVC group comprised 28 (72%) patients with definite and 11 (28%) with borderline diagnosis . As compared to controls, LVEF and RVEF were significantly lower in ARVC patients (61(interquartile range (IQR) 52-71) vs. 71%(IQR 55-88) , p = 0.03 and 47%(IQR 16-63) vs. 57%(IQR 49-63) , p = 0.02, respectively), LVEF remaining within normal range limits. While there was no significant difference in RV GLS between ARVC patients and controls (median -17.7%(IQR -24–15) vs. -17.5%(IQR -20.1–15.2), p = 0.67) , BCS and BRMF were significantly lower in ARVC patients vs. controls [-7.5%(IQR -12.3–8.4.) vs. -9.8%(IQR -13.8–8.6.), p = 0.004 and -12.2(IQR -14.4–8.7.) vs. -14.9%(IQR -16.6–13.2) p = 0.0007, respectively] . The LRSL area was significantly and markedly lower in ARVC patients vs. controls [70.6 (IQR 16.3-63.1) vs. 144.1 (IQR 110.4-251.3), p = 0.0002] . LRSL area outperformed RVEF, BCS and BRS in separating ARVC from controls (area under receiving operator characteristics curve 0.82 vs. 0.78, 0.73 and 0.78, respectively). Conclusion In ARVC, a FT-derived parameter combining longitudinal and radial RV wall deformation and motion provided better discrimination of ARVC patients from controls than conventional FT measurements. Its implementation in clinical practice may bolster CMR performance to characterize ARVC wall motion abnormalities. Abstract Figure

Evaluation of transfer learning in deep convolutional neural network models for cardiac short axis slice classification

In computer-aided analysis of cardiac MRI data, segmentations of the left ventricle (LV) and myocardium are performed to quantify LV ejection fraction and LV mass, and they are performed after the identification of a short axis slice coverage, where automatic classification of the slice range of interest is preferable. Standard cardiac image post-processing guidelines indicate the importance of the correct identification of a short axis slice range for accurate quantification. We investigated the feasibility of applying transfer learning of deep convolutional neural networks (CNNs) as a means to automatically classify the short axis slice range, as transfer learning is well suited to medical image data where labeled data is scarce and expensive to obtain. The short axis slice images were classified into out-of-apical, apical-to-basal, and out-of-basal, on the basis of short axis slice location in the LV. We developed a custom user interface to conveniently label image slices into one of the three categories for the generation of training data and evaluated the performance of transfer learning in nine popular deep CNNs. Evaluation with unseen test data indicated that among the CNNs the fine-tuned VGG16 produced the highest values in all evaluation categories considered and appeared to be the most appropriate choice for the cardiac slice range classification.

Prognostic Value of Nonischemic Ringlike Left Ventricular Scar in Patients With Apparently Idiopathic Nonsustained Ventricular Arrhythmias.

Left ventricular (LV) scar on late gadolinium enhancement (LGE) cardiac magnetic resonance has been correlated with life-threatening arrhythmic events in patients with apparently idiopathic ventricular arrhythmias (VAs). We investigated the prognostic significance of a specific LV-LGE phenotype characterized by a ringlike pattern of fibrosis. A total of 686 patients with apparently idiopathic nonsustained VA underwent contrast-enhanced cardiac magnetic resonance. A ringlike pattern of LV scar was defined as LV subepicardial/midmyocardial LGE involving at least 3 contiguous segments in the same short-axis slice. The end point of the study was time to the composite outcome of all-cause death, resuscitated cardiac arrest because of ventricular fibrillation or hemodynamically unstable ventricular tachycardia and appropriate implantable cardioverter defibrillator therapy. A total of 28 patients (4%) had a ringlike pattern of scar (group A), 78 (11%) had a non-ringlike pattern (group B), and 580 (85%) had normal cardiac magnetic resonance with no LGE (group C). Group A patients were younger compared with groups B and C (median age, 40 vs 52 vs 45 years; P<0.01), more frequently men (96% vs 82% vs 55%; P<0.01), with a higher prevalence of family history of sudden cardiac death or cardiomyopathy (39% vs 14% vs 6%; P<0.01) and more frequent history of unexplained syncope (18% vs 9% vs 3%; P<0.01). All patients in group A showed VA with a right bundle-branch block morphology versus 69% in group B and 21% in group C (P<0.01). Multifocal VAs were observed in 46% of group A patients compared with 26% of group B and 4% of group C (P<0.01). After a median follow-up of 61 months (range, 34-84 months), the composite outcome occurred in 14 patients (50.0%) in group A versus 15 (19.0%) in group B and 2 (0.3%) in group C (P<0.01). After multivariable adjustment, the presence of LGE with ringlike pattern remained independently associated with increased risk of the composite end point (hazard ratio, 68.98 [95% CI, 14.67-324.39], P<0.01). In patients with apparently idiopathic nonsustained VA, nonischemic LV scar with a ringlike pattern is associated with malignant arrhythmic events.