Evaluation of Pulmonary Hypertension Using 4D Flow MRI.

BACKGROUND: Cardiac magnetic resonance imaging (MRI) is becoming an alternative to right heart catheterization (RHC) for evaluating pulmonary hypertension (PH). A need exists to further evaluate cardiac MRI's ability to characterize PH. PURPOSE: To evaluate the potential for four-dimensional (4D) flow MRI-derived pulmonary artery velocities to characterize PH. STUDY TYPE: Prospective case-control. POPULATION: Fifty-four PH patients (56% female); 25 controls (36% female). FIELD STRENGTH/SEQUENCE: 1.5 T; gradient recalled echo 4D flow and balanced steady-state free precession cardiac cine. ASSESSMENT: RHC was used to derive patients' pulmonary vascular resistance (PVR). 4D flow measured blood velocities at the main, left, and right pulmonary arteries (MPA, LPA, and RPA); cine measured ejection fraction, end diastolic, and end systolic volumes (EF, EDV, and ESV). EDV and ESV were normalized (indexed) to body surface area (ESVI and EDVI). Parameters were evaluated between, and within, PH subgroups: pulmonary arterial hypertension (PAH); PH due to left heart disease (PH-LHD)/chronic lung disease (PH-CLD)/or chronic thrombo-emboli (CTE-PH). STATISTICAL TESTS: Analysis of variance and Kruskal-Wallis tests compared parameters between subgroups. Pearson's r assessed velocity, PVR, and volume correlations. Significance definition: P < 0.05. RESULTS: PAH peak and mean velocities were significantly lower than in controls at the LPA (36 ± 12 cm/second and 20 ± 4 cm/second vs. 59 ± 15 cm/second and 32 ± 9 cm/second). At the RPA, mean velocities were significantly lower in PAH vs. controls (27 ± 6 cm/second vs. 40 ± 9 cm/second). Peak velocities significantly correlated with right ventricular EF at the MPA (r = 0.286), RPA (r = 0.400), and LPA (r = 0.401). Peak velocity significantly correlated with right ventricular ESVI at the RPA (r = -0.355) and LPA (r = -0.316). Significant correlations between peak velocities and PVR were moderate at the LPA in PAH (r = -0.641) and in PH-LHD (r = -0.606) patients, and at the MPA in PH-CLD (r = -0.728). CTE-PH showed non-significant correlations between peak velocity and PVR at all locations. DATA CONCLUSION: Preliminary findings suggest 4D flow can identify PAH and track PVR changes. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 5.

Cine MRI characterizes HFpEF and HFrEF in post-capillary pulmonary hypertension.

PURPOSE: To test the hypothesis that cine MRI can be used to characterize features of left and right ventricles in post-capillary pulmonary hypertension (PH) caused by heart failure (HF) with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). METHODS: With the approval of institution review board (IRB), 28 consecutive post-capillary PH patients (11 males, 62.1 ± 13.4 years old, range 39-89 years old) underwent cine MRI scans. Cine MRI-derived left ventricular (LV) ejection fraction (LVEF) and other function, motion, and deformation indices (acquired with heart deformation analysis [HDA]) were compared between PH-HFpEF (defined as LVEF ≥ 50 %]) and PH-HFrEF (LVEF < 50 %) patients and were related with right ventricular (RV) indices and right heart catheterization (RHC)-derived pulmonary artery measurements. RESULTS: Totally 19 patients (68 %, 95 % confident interval [CI] 49 %-86 %) were assigned to PH-HFpEF group while 9 (32 %) was assigned to the PH-HFrEF group. There were differences of LV and right ventricular (RV) global functional indices, LV mass, LV displacement, velocity, strain and strain rate between the two patient groups. Cine MRI-derived LV indices had broad associations with RV indices and RHC measurements. LVEF was negatively correlated with pulmonary capillary wedge pressure (PCWP) (r = -0.5, p = 0.007). LV cardiac index (LVCI) was associated with systolic pulmonary artery pressure (sPAP) (r = 0.443, p = 0.018). CONCLUSIONS: PH-HFpEF and PH-HFrEF patients present dissimilar function, motion and deformation features in LV and RV. Cine MRI-derived LV measures are correlated with hemodynamic abnormalities of PH.

Cine MRI detects elevated left heart pressure in pulmonary hypertension.

Cine magnetic resonance imaging (MRI) is an emerging modality for evaluating left ventricular (LV) motion/deformation patterns, which may have potential to identify LV dysfunctions underlying postcapillary pulmonary hypertension (PH). The aim of this study was to test the hypothesis that cine MRI-derived LV motion/deformation indices can be used to identify an elevated left heart pressure in PH. This was a retrospective study, which included 26 precapillary and 28 postcapillary PH patients (23 males, 58.9 ± 13.5 years old). All patients underwent right heart catheterization (the "reference standard") and cardiac MRI. Balanced steady-state free precession cine sequence acquired at 1.5 T was used. Cine MRI datasets were analyzed by using heart deformation analysis. LV motion/deformation indices were measured through 25 phases within a cardiac cycle. Peak LV displacement, velocity, strain, and strain rates at systole, early and late diastole were compared between the two patient groups using t-tests. The Pearson correlation coefficient (r) was used to investigate the association between cine MRI-derived indices and pulmonary capillary wedge pressure (PCWP). Multivariable linear and logistic regression models were applied to assess the ability of MRI-derived parameters to predict PCWP and postcapillary PH. Compared to 26 precapillary PH patients, the 28 postcapillary PH patients had lower peak late radial diastolic displacement (0.43 ± 0.19 cm vs. 0.64 ± 0.18 cm) and velocity (12.2 ± 5.8 mm/s vs. 18.9 ± 5.6 mm/s) and peak late radial (52.1 ± 32.7%/s vs. 97.1 ± 38%/s) and circumferential (38 ± 19.8%/s vs. 63.1 ± 22.9%/s) strain rates. PCWP was correlated with peak late radial diastolic displacement (r = -0.54) and velocity (r = -0.57) and peak late radial (r = -0.63) and circumferential diastolic (r = -0.63) strain rates. Peak late radial strain rate could predict PCWP (ß = -0.09) and postcapillary PH (ß = -0.036). All p < 0.05. Cine MRI-derived LV late diastolic motion/deformation properties can be used to estimate elevated left heart pressure in PH. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 1.

Aortic annular dimensions by non-contrast MRI using k-t accelerated 3D cine b-SSFP in pre-procedural assessment for transcatheter aortic valve implantation: a technical feasibility study.

To evaluate k-t accelerated 3D cine b-SSFP (balanced steady state free precession) as magnetic resonance imaging (MRI) technique for aortic annular area measurement in transcatheter aortic valve replacement (TAVR) planning compared to computed tomography angiography (CTA) and other non-contrast MRI sequences with reduced imaging time and without contrast administration. 6 volunteers and 7 TAVR candidates were prospectively enrolled. The volunteers underwent an MRI while TAVR candidates underwent an MRI and CTA. The following non-contrast MRI sequences were obtained at the level of the aortic root: 2D cine b-SSFP [GRAPPA (GeneRalized Autocalibrating Partially Parallel Acquisitions), R = 2], 3D cine b-SSFP [GRAPPA R = 2], navigator triggered 3D b-SSFP MRA [GRAPPA, R = 2] and k-t accelerated 3D cine b-SSFP [PEAK GRAPPA, R = 5]. Qualitative analysis and aortic annular area measurements in systole and diastole were obtained. k-t accelerated 3D cine b-SSFP provided image quality that is acceptable for confident diagnosis with very good interrater agreement. There was no statistically significant difference in aortic annular measurements between k-t accelerated 3D cine b-SSFP and CTA or other MRI sequences (p > 0.05). Bland-Altman analysis showed no systemic difference of annular area measurements between k-t accelerated 3D cine b-SSFP and each of the other techniques. There was excellent inter-rater agreement on aortic annular area measurements during systolic (ICC = 0.976, p < 0.001) and diastolic (ICC = 0.971, p < 0.001) phases using k-t accelerated 3D cine b-SSFP. K-t accelerated 3D cine b-SSFP is a promising alternative for the assessment of annular sizing in pre-TAVR evaluation while offering a reasonable combination of imaging parameters during one breath-hold.

Four-dimensional Flow Magnetic Resonance Imaging Quantification of Blood Flow in Bicuspid Aortic Valve.

BACKGROUND: Four-dimensional (D) flow magnetic resonance imaging (MRI) is limited by time-consuming and nonstandardized data analysis. We aimed to test the efficiency and interobserver reproducibility of a dedicated 4D flow MRI analysis workflow. MATERIALS AND METHODS: Thirty retrospectively identified patients with bicuspid aortic valve (BAV, age=47.8±11.8 y, 9 male) and 30 healthy controls (age=48.8±12.5 y, 21 male) underwent Aortic 4D flow MRI using 1.5 and 3 T MRI systems. Two independent readers performed 4D flow analysis on a dedicated workstation including preprocessing, aorta segmentation, and placement of four 2D planes throughout the aorta for quantification of net flow, peak velocity, and regurgitant fraction. 3D flow visualization using streamlines was used to grade aortic valve outflow jets and extent of helical flow. RESULTS: 4D flow analysis workflow time for both observers: 5.0±1.4 minutes per case (range=3 to 10 min). Valve outflow jets and flow derangement was visible in all 30 BAV patients (both observers). Net flow, peak velocity, and regurgitant fraction was significantly elevated in BAV patients compared with controls except for regurgitant fraction in plane 4 (91.1±29.7 vs. 62.6±19.6 mL/s, 37.1% difference; 121.7±49.7 vs. 90.9±26.4 cm/s, 28.9% difference; 9.3±10.1% vs. 2.0±3.4%, 128.0% difference, respectively; P<0.001). Excellent intraclass correlation coefficient agreement for net flow: 0.979, peak velocity: 0.931, and regurgitant fraction: 0.928. CONCLUSION: Our study demonstrates the potential of an efficient data analysis workflow to perform standardized 4D flow MRI processing in under 10 minutes and with good-to-excellent reproducibility for flow and velocity quantification in the thoracic aorta.

Prognostic Value of Myocardial Extracellular Volume Fraction and T2-mapping in Heart Transplant Patients.

OBJECTIVES: The purpose of this study was to examine prognostic value of T1- and T2-mapping techniques in heart transplant patients. BACKGROUND: Myocardial characterization using T2 mapping (evaluation of edema/inflammation) and pre- and post-gadolinium contrast T1 mapping (calculation of extracellular volume fraction [ECV] for assessment of interstitial expansion/fibrosis) are emerging modalities that have been investigated in various cardiomyopathies. METHODS: A total of 99 heart transplant patients underwent the magnetic resonance imaging (MRI) scans including T1- (n = 90) and T2-mapping (n = 79) techniques. Relevant clinical characteristics, MRI parameters including late gadolinium enhancement (LGE), and invasive hemodynamics were collected. Median clinical follow-up duration after the baseline scan was 2.4 to 3.5 years. Clinical outcomes include cardiac events (cardiac death, myocardial infarction, coronary revascularization, and heart failure hospitalization), noncardiac death and noncardiac hospitalization. RESULTS: Overall, the global native T1, postcontrast T1, ECV, and T2 were 1,030 ± 56 ms, 458 ± 84 ms, 27 ± 4% and 50 ± 4 ms, respectively. Top-tercile-range ECV (ECV >29%) independently predicted adverse clinical outcomes compared with bottom-tercile-range ECV (ECV <25%) (hazard ratio [HR]: 2.87; 95% confidence interval [CI]: 1.07 to 7.68; p = 0.04) in a multivariable model with left ventricular end-systolic volume and LGE. Higher T2 (T2 ≥50.2 ms) independently predicted adverse clinical outcomes (HR: 3.01; 95% CI: 1.39 to 6.54; p = 0.005) after adjustment for left ventricular ejection fraction, left ventricular end-systolic volume, and LGE. Additionally, higher T2 (T2 ≥50.2 ms) also independently predicted cardiac events (HR: 4.92; CI: 1.60 to 15.14; p = 0.005) in a multivariable model with left ventricular ejection fraction. CONCLUSIONS: MRI-derived myocardial ECV and T2 mapping in heart transplant patients were independently associated with cardiac and noncardiac outcomes. Our findings highlight the need for larger prospective studies.

Steady State Magnetic Resonance Angiography of the Thoracic Aorta Using Inversion-recovery Steady-State Free Precession and a High Relaxivity Contrast Agent.

PURPOSE: To evaluate image quality and aortic dimension measurement accuracy of high resolution, motion compensated steady-state magnetic resonance angiography (SS-MRA) with a high relaxivity, extracellular fluid gadolinium-based contrast agent compared with standard first-pass contrast enhanced MRA (FP-CEMRA) in patients with thoracic aortic aneurysms. MATERIALS AND METHODS: Sixty-nine patients (mean age, 51.7 y, 25% female) diagnosed with thoracic aortic aneurysms who underwent MRA on a 1.5 T scanner using FP-CEMRA and SS-MRA techniques were retrospectively identified. Quantitative analysis was performed by measuring the aortic diameters at 6 locations within the thoracic aorta for each technique. Two radiologists independently performed the qualitative analysis by assessing the image quality (1 to 5), presence of artifact (1 to 4), signal-to-noise (1 to 4), contrast-to-noise (1 to 4), and wall conspicuity (1 to 4) in the aorta at 4 different locations: the aortic root, the ascending aorta, the aortic arch, and the descending aorta. RESULTS: The aortic dimensions obtained by SS-MRA had a good correlation with FP-CEMRA. Means for the aortic diameters between the FP-CEMRA and the SS-MRA at all 6 locations demonstrated minimal mean differences (0.013 to 0.044 mm).Qualitative assessment of aorta at 4 locations by 2 reviewers demonstrated that SS-MRA had on average superior image quality at the aortic root and ascending aorta for both reviewers (P<0.05) and at the descending aorta for one reader (P<0.05). Otherwise, both techniques were comparable at the ascending aorta. SS-MRA demonstrated less artifact at the aortic root and the ascending aorta (P<0.05). CONCLUSION: Aortic dimension measurements provided by SS-MRA with a high relaxivity, extracellular fluid gadolinium-based contrast agent are comparable to the conventional FP-CEMRA. Furthermore, SS-MRA qualitatively demonstrated comparable to better overall image quality than FP-CEMRA at different aortic locations. Therefore, SS-MRA may provide a comparable alternative, or complementary examination to conventional FP-CEMRA in patients who have difficulty breath holding, or in situations where contrast bolus timing was poor.

Evaluating Biventricular Myocardial Velocity and Interventricular Dyssynchrony in Adult Patients During the First Year After Heart Transplantation.

BACKGROUND: Magnetic resonance tissue phase mapping (TPM) measures three-directional myocardial velocities of the left and right ventricle (LV, RV). This noninvasive technique may supplement endomyocardial biopsy (EMB) in monitoring grafts post-heart transplantation (HTx). PURPOSE: To assess biventricular myocardial velocity alterations in grafts and investigate the relationship between velocities and acute cellular rejection (ACR) episodes. STUDY TYPE: Prospective. SUBJECTS: Twenty-seven patients within 1 year post-HTx (49 ± 13 years, 19 M) and 18 age-matched controls (49 ± 15 years, 12 M). FIELD STRENGTH/SEQUENCE: 1.5T, 2D balanced steady-state free precession, and TPM. ASSESSMENT: Ventricular function: end-diastolic and end-systolic volumes, stroke volumes, ejection fraction (EF), and myocardial mass. TPM velocities: peak-systolic and peak-diastolic velocities, cardiac twist, and interventricular dyssynchrony. ACR rejection episodes: International Society for Heart and Lung Transplantation grading of EMB specimens. STATISTICAL TESTS: The Lilliefors test for normality, unpaired t-tests, and Wilcoxon rank-sum tests for normally and nonnormally distributed data, respectively, were used, as well as multivariate regression for confounding variables and Pearson's correlation for associations between TPM velocities and global function. RESULTS: Compared to controls, HTx patients demonstrated reduced biventricular systolic longitudinal velocities (LV: 5.2 ± 2.1 vs. 4.0 ± 1.5 cm/s, P < 0.05; RV: 4.2 ± 1.3 vs. 3.1 ± 1.2 cm/s, P < 0.01). Correlation analysis revealed significant positive relationships for biventricular EF with radial peak velocities of the same ventricle in both systole and diastole (LV systole: r = 0.48, P < 0.01; LV diastole: r = 0.28, P < 0.05; RV systole: r = 0.35, P < 0.01; RV diastole: r = 0.36, P < 0.01). Segmentally, longitudinal velocities were impaired in 7/16 LV segments and 5/10 RV segments in systole and 7/10 RV segments in diastole. TPM analysis in studies with >4 preceding ACR episodes showed globally reduced RV and LV systolic radial velocity, and segmentally reduced radial and longitudinal systolic velocities. DATA CONCLUSION: Biventricular global and segmental velocities were reduced in HTx patients. Patients with >4 rejection episodes showed reduced myocardial velocities. The TPM sequence may add functional information for monitoring graft dysfunction. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:920-929.

Semi-quantitative myocardial perfusion MRI in heart transplant recipients at rest: repeatability in healthy controls and assessment of cardiac allograft vasculopathy.

BACKGROUND: Cardiac Allograft Vasculopathy (CAV) is a major cause of chronic cardiac allograft failure. Invasive coronary angiography (ICA) and intravascular ultrasound (IVUS) are the current diagnostic methods. Myocardial perfusion MRI has become a promising non-invasive method to evaluate myocardial ischemia, but has not been thoroughly validated in CAV. Our objective was to assess the repeatability of myocardial rest-perfusion MRI in healthy volunteers and its feasibility in detecting CAV in transplant patients (Tx). METHODS: Twelve healthy volunteers and twenty transplant patients beyond the first year post- transplant underwent cardiac MRI at 1.5 T at rest including first-pass perfusion imaging in short axis (base, mid, apex) after injection of gadolinium. Volunteers underwent repeated cardiac MRI on different days (interval = 15.6 ± 2.4 days) to assess repeatability. Data analysis included semi-automatic contouring of endocardial and epicardial borders of the left ventricle (LV) and quantification of peak perfusion, time-to-peak (TTP) perfusion, and upslope of the perfusion curve. RESULTS: Between scans and re-scans in healthy volunteers, peak signal intensity, slope, and TTP demonstrated moderate agreement (ICC = 0.53, 0.48, and 0.59, respectively; all, p < .001). Peak signal intensity, slope, and TTP were moderately variable with COV values of 23%, 42%, and 35%, respectively. Peak perfusion was significantly reduced in CAV positive (n = 9 Tx patients) compared to CAV negative (n = 11 Tx patients) groups (90.7 ± 27.0 vs 139.5 ± 30.2, p < .001). CONCLUSION: Cardiac MRI is a moderately repeatable method for the semi-quantitative assessment of first-pass myocardial perfusion at rest. Semi-quantitative surrogate markers of LV perfusion could play a role in CAV detection.

Prenatal exposure to nitrate in drinking water and the risk of congenital anomalies.

BACKGROUND: Nitrate is a common water contaminant that has been associated with birth defects, although the evidence is limited. The purpose of this study was to examine whether maternal consumption of nitrate through drinking water is associated with an increased risk of congenital anomalies. METHODS: The study included a total of 348,250 singletons births from the state of Missouri between January 1, 2004 and December 31, 2008. Individual-level birth defect data and maternal and child characteristics were obtained from the Missouri birth defects registry and state vital statistics records. Outcomes were linked with county-specific monthly estimates of the nitrate concentration in finished water, based on data collected for compliance with the Safe Drinking Water Standard. Poisson models were fit to examine the association between nitrate exposure and birth defects. Average nitrate exposure during the first trimester and over 12 months prior to birth were modeled as continuous variables. Sensitivity analyses included restriction of the sample to counties with <20% and <10% private well usage to reduce exposure misclassification as well as limiting the analyses to residents of rural counties only to account for potential confounding by urbanicity. RESULTS: Estimated water concentrations of nitrate were generally low and below the Environmental Protection Agency's maximum contaminant level of 10 mg/L. Nitrate exposure was associated with a significantly increased risk of limb deficiencies (RR for 1 mg/L (RR1) = 1.26, 95% CI = 1.05, 1.51) in models without well restriction. Nitrate was also weakly associated with an increased risk of congenital heart defects (RR1 = 1.13, 95%CI = 0.93, 1.51) and neural tube defects (RR1 = 1.18, 95%CI = 0.93, 1.51) in models with well restriction (<10%). CONCLUSION: The positive associations found between nitrate exposure via drinking water and congenital abnormalities are largely consistent with some previous epidemiologic studies. The results of this study should be interpreted with caution given limitations in our ability to estimate exposures and the lack information on some risk factors for congenital abnormalities. Our findings may have serious policy implications given that exposure levels in our study were well below current EPA standards for nitrate in drinking water.

Multiparametric Cardiac Magnetic Resonance Imaging Can Detect Acute Cardiac Allograft Rejection After Heart Transplantation.

OBJECTIVES: The purpose of this study was to evaluate the sensitivity of multiparametric cardiac magnetic resonance imaging (CMR) for the detection of acute cardiac allograft rejection (ACAR). BACKGROUND: ACAR is currently diagnosed by endomyocardial biopsy, but CMR may be a noninvasive alternative because of its capacity for regional myocardial structure and function characterization. METHODS: Fifty-eight transplant recipients (mean age 47.0 ± 14.7 years) and 14 control subjects (mean age 47.7 ± 16.7 years) were prospectively recruited from August 2014 to May 2017 and underwent 97 CMR studies (83 transplant recipients, 14 control subjects) for assessment of global left ventricular function and myocardial T2, T1, and extracellular volume fraction (ECV). CMR studies were divided into 4 groups on the basis of biopsy grade: control subjects (n = 14), patients with no ACAR (no history of ACAR; n = 36), patients with past ACAR (history of ACAR; n = 24), and ACAR+ patients (active grade ≥1R ACAR; n = 23). RESULTS: Myocardial T2 was significantly higher in patients with past ACAR compared with those with no ACAR (51.0 ± 3.8 ms vs. 49.2 ± 4.0 ms; p = 0.02) and in patients with no ACAR compared with control subjects (49.2 ± 4.0 ms vs. 45.2 ± 2.3 ms; p < 0.01). ACAR+ patients demonstrated increased T2 compared with the no ACAR group (52.4 ± 4.7 ms vs. 49.2 ± 4.0 ms, p < 0.01) but not compared with the past ACAR group. In contrast, ECV was significantly elevated in ACAR+ patients compared with transplant recipients without ACAR regardless of history of ACAR (no ACAR: 31.5 ± 3.9% vs. 26.8 ± 3.3% [p < 0.01]; past ACAR: 31.5 ± 3.9% vs. 26.8 ± 4.0% [p < 0.01]). Receiver operating characteristic curve analysis revealed that a combined model of age at CMR, global T2, and global ECV was predictive of ACAR (area under the curve = 0.84). CONCLUSIONS: The combination of CMR-derived myocardial T2 and ECV has potential as a noninvasive tissue biomarker for ACAR. Larger studies during acute ACAR are needed for continued development of multiparametric CMR for transplant recipient surveillance.

Cardiac Structure-Function MRI in Patients After Heart Transplantation.

BACKGROUND: Following heart transplantation (Tx), recipients are closely monitored using endomyocardial biopsy, which is limited by cost and invasiveness, and echocardiography, which is limited regarding detailed structural and functional evaluation. PURPOSE: To test the feasibility of comprehensive structure-function cardiac MRI as a noninvasive modality to assess changes in myocardial structure and function. STUDY TYPE: Prospective. SUBJECTS: MR was performed in 61 heart transplant recipients (age 47.9 ± 16.3 years, 39% female) and 14 age-matched healthy controls (age 47.7 ± 16.7 years, 36% female). FIELD STRENGTH/SEQUENCE: 1.5T; 2D CINE steady state free precession (SSF)P imaging, T2 -mapping, pre- and postgadolinium contrast T1 -mapping, and tissue-phase mapping (TPM). ASSESSMENT: Quantification of myocardial T2 (as a measure of edema), pre- and post-Gd T1 (allowing calculation of extracellular volume (ECV) to estimate interstitial expansion), and TPM-based assessment of peak regional left ventricular (LV) velocities, dyssynchrony, and twist. STATISTICAL TESTS: Comparisons between transplant recipients and controls were performed using independent samples t-tests. Relationships between structural (T2 , T1 , ECV) and functional measures (myocardial velocities, dyssynchrony, twist) were assessed using Pearson correlation analysis. RESULTS: T2 and T1 were significantly elevated in transplant recipients compared to controls (global T2 : 50.5 ± 3.4 msec vs. 45.2 ± 2.3 msec, P < 0.01; global T1 : 1037.8 ± 48.0 msec vs. 993.8 ± 34.1 msec, P < 0.01). Systolic longitudinal function was impaired in transplant recipients compared to controls (reduced peak systolic longitudinal velocities, 2.9 ± 1.1 cm/s vs. 5.1 ± 1.2 cm/s, P < 0.01; elevated systolic longitudinal dyssynchrony, 60.2 ± 30.2 msec vs. 32.1 ± 25.1 msec, P < 0.01). Correlation analysis revealed a significant positive relationship between T2 and ECV (r = 0.45,P < 0.01). In addition, peak systolic longitudinal velocities demonstrated a significant inverse relationship with T2 (global r = -0.29, P = 0.02), and systolic radial dyssynchrony was positively associated with peak T2 and peak T1 (r = 0.26,P = 0.04; r = 0.27,P = 0.03). DATA CONCLUSION: MR techniques are sensitive to structural and functional differences in transplant recipients compared to controls. Structural (T2 , T1 ) and functional (peak myocardial velocities, dyssynchrony) measures were significantly associated, suggesting a structure-function relationship of cardiac abnormalities following heart transplant. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:678-687.

Donor and Recipient Characteristics in Heart Transplantation Are Associated with Altered Myocardial Tissue Structure and Cardiac Function.

PURPOSE: To use structure-function cardiac MRI in the evaluation of relationships between donor and heart transplantation (HTx) recipient characteristics and changes in cardiac tissue structure and function. HTx candidates and donor hearts are evaluated for donor-recipient matches to improve survival, but the impact of donor and recipient characteristics on changes in myocardial tissue and function in the transplanted heart is not fully understood. MATERIALS AND METHODS: Cardiac MRI at 1.5 T was performed from August 2014 to June 2017 in 58 HTx recipients (mean age, 51.1 years ± 12.6 [standard deviation], 26 female patients) and included T2 mapping (to evaluate edematous and/or inflammatory changes), precontrast and postcontrast T1 mapping (allowing the calculation of extracellular volume fraction [ECV] to estimate interstitial expansion), and tissue phase mapping (allowing the calculation of myocardial velocities and twist). Donor and recipient demographics (age, sex, height, weight, and body mass index [BMI]) and comorbidities (hypertension, diabetes, and smoking history) were evaluated for relationships with cardiac MRI measures. RESULTS: Sex-influenced cardiac MRI measures of myocardial tissue and function are as follows: Female HTx recipients demonstrated increased precontrast T1 (P = .002) and reduced systolic peak long-axis velocities (P = .015). Increased age of the donor heart was associated with elevated T2 (r = 0.32; P < .05) and ECV (r = 0.47; P < .01), indicating increased edema and interstitial expansion, as well as impaired diastolic peak long-axis velocities (r = 0.41; P < .01). Recipient-donor differences in age, weight, and BMI were significantly associated with elevated ECV (r = 0.36-0.48; P < .05). Hypertension in donors resulted in increased ECV (31.0% ± 4.2 vs 26.0% ± 3.3; P = .001). CONCLUSION: Donor and HTx recipient characteristics were significantly associated with cardiac MRI-derived measures of myocardial tissue structure and function.© RSNA, 2019.