Modified Look-Locker Inversion Recovery Sequence Research Articles

Cardiac MRI–derived Extracellular Volume Fraction versus Myocardium-to-Lumen R1 Ratio at Postcontrast T1 Mapping for Detecting Cardiac Amyloidosis

To evaluate the diagnostic performance of myocardium-to-lumen R1 (1/T1) ratio on postcontrast T1 maps for the detection of cardiac amyloidosis in a large patient sample. This retrospective study included consecutive patients who underwent MRI-derived extracellular volume fraction (MRI ECV) analysis between March 2017 and July 2021 because of known or suspected heart failure or cardiomyopathy. Pre- and postcontrast T1 maps were generated using the modified Look-Locker inversion recovery sequence. Diagnostic performances of MRI ECV and myocardium-to-lumen R1 ratio on postcontrast T1 maps (a simplified index not requiring a native T1 map and hematocrit level data) for detecting cardiac amyloidosis were evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. Of 352 patients (mean age, 63 years ± 16 [SD]; 235 men), 136 had cardiac amyloidosis. MRI ECV showed 89.0% (121 of 136; 95% CI: 82%, 94%) sensitivity and 98.6% (213 of 216; 95% CI: 96%, 100%) specificity for helping detect cardiac amyloidosis (cutoff value of 40% [AUC, 0.99 {95% CI: 0.97, 1.00}; P < .001]). Postcontrast myocardium-to-lumen R1 ratio showed 92.6% (126 of 136; 95% CI: 89%, 96%) sensitivity and 93.1% (201 of 216; 95% CI: 89%, 96%) specificity (cutoff value of 0.84 [AUC, 0.98 {95% CI: 0.95, 0.99}; P < .001]). There was no evidence of a difference in AUCs for each parameter (P = .10). Postcontrast myocardium-to-lumen R1 ratio showed excellent diagnostic performance comparable to that of MRI ECV in the detection of cardiac amyloidosis.Keywords: MR Imaging, Cardiac, Heart, Cardiomyopathies Supplemental material is available for this article. © RSNA, 2023.

Multi-site comparison of parametric T1 and T2 mapping: healthy travelling volunteers in the Berlin research network for cardiovascular magnetic resonance (BER-CMR)

BackgroundParametric mapping sequences in cardiovascular magnetic resonance (CMR) allow for non-invasive myocardial tissue characterization. However quantitative myocardial mapping is still limited by the need for local reference values. Confounders, such as field strength, vendors and sequences, make intersite comparisons challenging. This exploratory study aims to assess whether multi-site studies that control confounding factors provide first insights whether parametric mapping values are within pre-defined tolerance ranges across scanners and sites. MethodsA cohort of 20 healthy travelling volunteers was prospectively scanned at three sites with a 3 T scanner from the same vendor using the same scanning protocol and acquisition scheme. A Modified Look-Locker inversion recovery sequence (MOLLI) for T1 and a fast low-angle shot sequence (FLASH) for T2 were used. At one site a scan-rescan was performed to assess the intra-scanner reproducibility. All acquired T1- and T2-mappings were analyzed in a core laboratory using the same post-processing approach and software. ResultsAfter exclusion of one volunteer due to an accidentally diagnosed cardiac disease, T1- and T2-maps of 19 volunteers showed no significant differences between the 3 T sites (mean ± SD [95% confidence interval] for global T1 in ms: site I: 1207 ± 32 [1192–1222]; site II: 1207 ± 40 [1184–1225]; site III: 1219 ± 26 [1207–1232]; p = 0.067; for global T2 in ms: site I: 40 ± 2 [39–41]; site II: 40 ± 1 [39–41]; site III 39 ± 2 [39–41]; p = 0.543). ConclusionParametric mapping results displayed initial hints at a sufficient similarity between sites when confounders, such as field strength, vendor diversity, acquisition schemes and post-processing analysis are harmonized. This finding needs to be confirmed in a powered clinical trial.Trial registration ISRCTN14627679 (retrospectively registered)

Impaired myocardial calcium handling in people with type 2 diabetes: an in vivo manganese-enhanced magnetic resonance imaging study

Abstract Background There is a high prevalence of subclinical cardiac dysfunction in people with type 2 diabetes (T2D) which is associated with subsequent development of heart failure. Dysregulated myocardial calcium handling has been demonstrated in animal models of T2D and may be a key mechanism driving the development of heart failure. Manganese-enhanced cardiac magnetic resonance imaging (MEMRI) provides a unique method to assess in vivo myocardial calcium handling. Purpose To determine whether myocardial calcium handling is perturbed in people with T2D with no history of cardiovascular disease. We hypothesised that myocardial manganese uptake would be reduced in people with T2D compared with healthy volunteers. Methods Cross-sectional case-control study, adults with (n=20) and without (n=9) T2D underwent both gadolinium-enhanced MRI and MEMRI. Standard gadolinium-enhanced MRI was used to assess cardiac structure, function and tissue characteristics. MEMRI scans were performed within two weeks of the initial scan. Native T1 maps were obtained in the mid-short axis slice position using a Modified Look-Locker Inversion recovery sequence. An intravenous infusion of manganese dipyridoxyl diphosphate (5 μmol/kg (0.1 mL/kg) at 1 mL/min) was administered and T1 maps at the same location were repetitively acquired every 2.5 min for 30 min. Regions of interest were drawn in the inferoseptal segment and blood pool for all T1 maps from 0 to 30 min by a single observer. The primary outcome was the rate of manganese uptake which was assessed by Patlak modelling as a measure of myocardial calcium handling. Manganese uptake constants were compared using analysis of co-variance, with age, sex and body mass index as co-variates. Results Subjects with T2D were older (62±7 vs. 57±5 years, p=0.046) but body mass index (29.0±4.5 vs. 26.2±3.4 kg/m2, p=0.106), systolic (135±16 vs. 134±17 mmHg, p=0.809) and diastolic (81±10 vs. 83±9 mmHg, p=0.736) blood pressures were similar. Compared to control subjects, participants with T2D had normal systolic function but more concentric left ventricular remodelling (mass/volume ratio 0.90±0.14 vs. 0.71±0.06 g/mL, p&amp;lt;0.001) and reduced peak early diastolic strain rate (0.64±0.17 vs. 0.91±0.26 s–1, p=0.002). Myocardial manganese uptake was substantially reduced in people with T2D compared with controls (6.51±1.46 vs. 8.45±2.52 ml/100 g of tissue/min, p=0.003) (Figure 1). Conclusions For the first time, we have demonstrated in vivo that despite no history of cardiovascular disease and normal systolic function, patients with T2D have marked impairment of myocardial calcium handling. This has potential major implications for the pathogenesis, diagnosis and treatment of diabetic cardiomyopathy. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): British Heart Foundation and National Institute for Health Research

Improving accuracy of myocardial T1 estimation in MyoMapNet.

To improve the accuracy and robustness of T1 estimation by MyoMapNet, a deep learning-based approach using 4 inversion-recovery T1 -weighted images for cardiac T1 mapping. MyoMapNet is a fully connected neural network for T1 estimation of an accelerated cardiac T1 mapping sequence, which collects 4 T1 -weighted images by a single Look-Locker inversion-recovery experiment (LL4). MyoMapNet was originally trained using in vivo data from the modified Look-Locker inversion recovery sequence, which resulted in significant bias and sensitivity to various confounders. This study sought to train MyoMapNet using signals generated from numerical simulations and phantom MR data under multiple simulated confounders. The trained model was then evaluated by phantom data scanned using new phantom vials that differed from those used for training. The performance of the new model was compared with modified Look-Locker inversion recovery sequence and saturation-recovery single-shot acquisition for measuring native and postcontrast T1 in 25 subjects. In the phantom study, T1 values measured by LL4 with MyoMapNet were highly correlated with reference values from the spin-echo sequence. Furthermore, the estimated T1 had excellent robustness to changes in flip angle and off-resonance. Native and postcontrast myocardium T1 at 3Tesla measured by saturation-recovery single-shot acquisition, modified Look-Locker inversion recovery sequence, and MyoMapNet were 1483 ± 46.6ms and 791 ± 45.8ms, 1169 ± 49.0ms and 612 ± 36.0ms, and 1443 ± 57.5ms and 700 ± 57.5ms, respectively. The corresponding extracellular volumes were 22.90% ± 3.20%, 28.88% ± 3.48%, and 30.65% ± 3.60%, respectively. Training MyoMapNet with numerical simulations and phantom data will improve the estimation of myocardial T1 values and increase its robustness to confounders while also reducing the overall T1 mapping estimation time to only 4 heartbeats.

Patients with repaired tetralogy of Fallot and the HIF1A1744C/T variant have increased imaging markers of diffuse myocardial fibrosis

BackgroundRight ventricular fibrotic remodeling has been identified pre- and postoperatively in patients with tetralogy of Fallot (ToF) and linked to adverse outcomes. Polymorphisms of hypoxia inducible factor-1-alpha (HIF1A) have been associated with the fibrotic burden by cardiac magnetic resonance (CMR) late gadolinium enhancement imaging. Their association with diffuse fibrotic myocardial remodeling is unknown. We sought to determine whether polymorphisms in HIF1A are related to CMR markers of diffuse myocardial fibrosis. MethodsPatients with repaired ToF who had undergone CMR with T1 mapping as well as whole genome sequencing were included. Myocardial native T1 was quantified using a modified Look-Locker inversion recovery sequence and measured in the left ventricular free wall, the interventricular septum, and the right ventricular free wall. Patients who had at least one functioning allele of HIF1A were compared to those who did not using the Mann Whitney U test for continuous variables and chi-square or the Fischer test for discrete variables. Results46 patients had both CMR and whole genome sequencing. Only one HIF1A variant was identified in the cohort and present in 13 patients. There were no significant differences in demographics, surgical variables, right or left ventricular volumes or function between patients with and without the variant. Despite a trend towards a lower age at the time of CMR (11.3 vs 13.7 years; p = 0.07), patients with HIF1A variants had higher native T1 values (1094 vs. 1050; p = 0.027) in the right ventricular outflow tract myocardium, reflecting increased diffuse interstitial ventricular fibrosis in them. ConclusionHypoxia-inducible factor is associated with imaging markers of increased diffuse right ventricular fibrosis late after repair of tetralogy of Fallot.

Abstract 14147: Septal Native T1 is Higher in Patients With Pre-Capillary Pulmonary Hypertension Compared to Post-Capillary Pulmonary Hypertension

Introduction: Right heart catheterization (RHC) is used to diagnose and classify pulmonary hypertension (PH). Because RHC is invasive, there is growing interest in non-invasive PH evaluation techniques, such as cardiac magnetic resonance (CMR). Hypothesis: CMR-derived fibrosis indices [native T1 (NT1) and extracellular volume (ECV)] differ between pre-capillary PH (PRE-PH), post-capillary PH (POST-PH) and controls. Methods: RHC-defined PH patients and healthy controls (N=25, age=52+/-13 years) underwent CMR. A cardiologist classified patients into PRE-PH (N=29, age=55+/-8 years) and POST-PH (N=19, age=66+/-13 years) based on RHC measurements and clinical history. T1 maps of the left ventricle were acquired using a Modified Look-Locker Inversion Recovery sequence before and after administration of gadolinium contrast. T1 maps were manually segmented using the AHA 16 segment model to obtain segmental native and post-contrast T1. Segmental ECV was calculated using NT1, post-contrast T1, and hematocrit. Global ECV and NT1 were calculated by averaging all segments. Results: PRE-PH had higher NT1 than POST-PH in segments 8 (1077+/-39 vs 1046+/-36 ms, p=.01), 9 (1082+/-47 vs 1051+/-44 ms, p=.03), and 14 (1080+/-74 vs 1028+/-53 ms, p=.01). Global ECV and NT1 were higher in PRE-PH (31+/-4% and 1056+/-36 ms) than controls (28+/-4% and 1013+/-29 ms) (p=.017 and p=.000, respectively). Conclusions: NT1 was different between PRE-PH and POST-PH in mid- and apical-septal segments, however segmental ECV and global measures were not. NT1 may reflect more than just ECV expansion, providing additional insight into the myocardium. Regional NT1 may complement RHC for classifying PH.

Hypoxia inducible factor (HIF1A) is associated with increased right ventricular fibrosis by T1 mapping cardiac magnetic resonance in patients with repaired tetralogy of Fallot

Abstract Background Right ventricular fibrotic remodeling has been identified pre- and postoperatively in patients with tetralogy of Fallot (ToF) and linked to adverse outcomes. Polymorphisms of hypoxia inducible factor-1-alpha (HIF1α) have been associated with fibrotic burden by cardiac magnetic resonance (CMR) late gadolinium enhancement imaging. Their association with diffuse fibrotic myocardial remodeling is unknown. Purpose We sought to determine whether polymorphisms in hypoxia inducible factor (HIF1α) are related to CMR markers of diffuse myocardial fibrosis in pediatric patients with repaired ToF. Methods Patients with repaired ToF who had undergone CMR with T1 mapping as well as whole genome sequencing were included. Myocardial native T1 was quantified using a modified Look-Locker inversion recovery sequence and measured in the left ventricular free wall, the interventricular septum, and the right ventricular free wall. Patients who had at least one functioning allele of HIF1α were compared to those who did not using Mann Whitney U test for continuous variables and chi-square or Fischer test for discrete variables. Data are displayed in Table 1 as median (IQR) for continuous variables and frequency (percentage) for discrete variables. Results 46 patients had both CMR and whole genome sequencing. Only one HIF1α variant was identified in the cohort and present in 13 patients. There were no significant differences in demographics, surgical variables, right or left ventricular volumes or function between the groups (Table 1). Despite a trend towards a lower age at the time of CMR (11.3 vs 13.7 years; p=0.07), patients with HIF1α had higher native T1 values (1094 vs. 1050; p=0.027; Table 1) in the right ventricular outflow tract myocardium, reflecting increased diffuse interstitial ventricular fibrosis in patients with the HIF1α variant. Conclusion Hypoxia-inducible factor is associated with imaging markers of increased diffuse right ventricular fibrosis late after repair of tetralogy of Fallot. Funding Acknowledgement Type of funding sources: None. Table 1

Nonenhanced Chemical Exchange Saturation Transfer Cardiac Magnetic Resonance Imaging in Patients With Amyloid Light-Chain Amyloidosis.

Chemical exchange saturation transfer (CEST) is an emerging metabolic MRI technique to map creatine distribution in the myocardium. To investigate the feasibility of using a contrast-free CEST technique to evaluate cardiac involvement in amyloid light-chain (AL) amyloidosis. Prospective. Forty patients with biopsy-proven AL amyloidosis (age 57.6 ± 9.1 years, 31 males) and 20 healthy controls (age 42.8 ± 13.8 years, 13 males). A 3.0 T, CEST imaging using a single-shot FLASH sequence, T1 mapping with a modified Look-Locker inversion recovery sequence and late gadolinium enhancement (LGE) imaging with a phase-sensitive inversion recovery gradient echo sequence. The average CEST was calculated in the basal short-axis slice of the entire left ventricle and septum. LGE was assessed subjectively (none/patchy/global) and extracellular volume (ECV), CEST and T1 maps generated. Comparison between patient groups and healthy controls was performed by one-way analysis of variance with post hoc Bonferroni correction. Correlation was assessed using the Pearson's r correlation or Spearman ρ correlation. Statistical significance was defined as P< 0.05. Global (0.09 ± 0.03 vs. 0.11 ± 0.02) and septal (0.09 ± 0.03 vs. 0.11 ± 0.03) basal short-axis CEST was significantly decreased in patients with AL amyloidosis compared to the controls. Global CEST correlated significantly with Mayo stage (ρ=-0.508), NYHA Class (ρ=-0.430), LVEF (r=0.511), mass index (r=-0.373), LGE (ρ=-0.537), ECV (r=-0.544), and T2 (r=-0.396). Septal CEST correlated significantly with LVEF (r=0.395), LGE (ρ=-0.330), and ECV (r=-0.391). This study highlights the potential of CEST MRI to identify cardiac involvement and evaluate disease burden and to give insight into cellular changes intermediary between function and structure in AL amyloidosis patients. 2 TECHNICAL EFFICACY: Stage 2.

Myocardial T1 Values at 1.5 T: Normal Values for General Electric Scanners and Sex-Related Differences.

No data are available about normal ranges for native T1 in human myocardium using General Electric (GE) scanners. To establish normal ranges for myocardial T1 values and evaluate regional variability and the influence of physiological factors. Prospective. One hundred healthy volunteers with normal electrocardiogram, no cardiovascular/systemic diseases, or risk factors (age range: 20-70 years; 50 females). 1.5 T/Steady-state free precession cine and a modified Look-Locker inversion recovery sequence in diastole (also in systole for 61 volunteers). Image analysis was performed by operators with >10 years experience in cardiac MR using commercially available software. T1 values were calculated for 16 myocardial segments, and the global value was the mean. Segments were grouped according to circumferential region (anterior, septal, inferior, and lateral) and to level (basal, medial, apical). Twenty images were analyzed twice by the same operator and by a different operator to assess reproducibility. Independent-samples t-test or Mann-Whitney test; paired sample t-test or Wilcoxon signed-rank test; one-way repeated measures ANOVA or Friedman tests; Pearson's or Spearman's correlation. Reproducibility evaluated using coefficient of variability (CoV). Due to artifacts and/or partial-volume effects, 45/1600 (2.8%) segments were excluded. A good intra- and inter-operator reproducibility was detected (CoV < 5%). There were significant differences in segmental T1 values (P< 0.05). A significant circumferential variability was present (P < 0.05): the mean native T1 value over the lateral region was significantly lower than in the other three regions. An increasing gradient from basal to apical slices was detected (P< 0.05). Segmental and global T1 values were not associated with age (range P=0.052-0.911) but were significantly lower in males than in females (global: 993 ± 32 vs. 1037 ± 27 ms; P < 0.05) and significantly correlated with heart rate (range R for segmental values=0.247-0.920; P< 0.05). Almost all segmental T1 values were inversely correlated with wall thickness (R from -0.233 to -0.514; P< 0.05). Systolic T1 values were significantly lower than diastolic values in basal anteroseptal segment, in all medial segments except the inferior one, and in all apical segments (P < 0.05). Myocardial T1 values differ among myocardial regions, are influenced by sex, heart rate, and wall thickness and vary according to the cardiac cycle in healthy adults. 2 TECHNICAL EFFICACY: Stage 2.

Abstract 14919: Myocardial T 1 Mapping for Prediction of Left Ventricular Reverse Remodeling in Patients With Recent-onset Dilated Cardiomyopathy: a Comparison With Histological Tissue Characterization

Background: Accurate prediction of left ventricular reverse remodeling (LVRR) in dilated cardiomyopathy (DCM) remains challenging. The purpose of this study is to assess the potential of cardiovascular magnetic resonance (CMR) T 1 mapping to predict LVRR by histological confirmation. Methods: Twenty-one DCM patients (12 male, mean age 49 ± 13 years) underwent cine, late gadolinium enhancement (LGE) CMR, and triple-slice T 1 mapping using a modified Look-Locker inversion recovery sequence at 3T before receiving optimal medical therapy. LVRR was defined as an absolute increase in LV ejection fraction (LVEF) from ≥10% to a final value of &gt;35%, accompanied by a decrease in LV end-diastolic volume (LVEDV) ≧10% at midterm (mean time 18 months) CMR follow-up. Extra-cellular volume (ECV) was quantified from pre and post-contrast T 1 values of the blood and myocardium with hematocrit correction. Biopsy samples were used for quantification of collagen volume fraction (CVF). Results: LVRR was observed in 11 patients (52%). The mean native T 1 , ECV, and histological CVF were 1395 ± 49 ms, 0.33 ± 0.03, 0.13 ± 0.04, respectively. Native T 1 yielded comparable ability to ECV measurements for detecting histological CVF (r=0.49, 0.52, both p &lt;0.05). While 14 patients (67%) showed focal scar on LGE, there was no significant difference in histological CVF between patients with and without focal scarring (p=0.6). Native T 1, but not ECV and CVF, correlated well with absolute LVEF increase and relative percent decrease of LVEDV and LV end-systolic volume (r=-0.55, 0.55, 0.56, all p &lt;0.05). Native T 1 &lt;1400 ms provided 90% sensitivity and 82% specificity, with the C-statistic of 0.86 (95% CI 0.64-0.97), for predicting LVRR. On the other hand, the C-statistic of ECV, LGE and histological CVF were 0.72 (95% CI 0.48-0.89), 0.53 (95% CI 0.31-0.75) and 0.66 (95% CI 0.43-0.85), respectively. Conclusions: Myocardial native T 1 have the potential to predict LVRR beyond LGE and histological assessment.

Native T1 mapping in diffuse myocardial diseases using 3-Tesla MRI: An institutional experience.

Aims:Newer cardiac magnetic resonance techniques like native T1 mapping are being used increasingly as an adjunct to diagnose myocardial diseases with fibrosis. However, its full clinical utility has not been tested extensively, especially in the Indian population. The purpose of this study was to find native T1 values in healthy individuals without cardiac disease in our 3-Tesla MRI system and examine whether native myocardial T1 values can be used to differentiate between normal and diffuse myocardial disease groups.Subjects and Methods:After approval from the institutional ethics committee, native T1 mapping was performed in 12 healthy individuals without cardiac disease who served as controls and in 26 patients with diffuse myocardial diseases (acute myocarditis (n = 5), hypertrophic cardiomyopathy (HCM) (n = 8), nonischemic dilated cardiomyopathy (DCM) (n = 7), restrictive cardiomyopathy (RCM) due to amyloidosis (n = 6)) in a 3-Tesla MRI system in short axis slices and four-chamber view using a modified Look-Locker inversion recovery sequence. The mean native T1 values and standard deviations were calculated for control and disease groups and compared. The ability of native myocardial T1 mapping to differentiate between normal and diffuse myocardial disease groups was assessed. One-way ANOVA with Tukey's Post-Hoc test was used to find significant difference in the multivariate analysis and Chi-Square test was used to find the significance in categorical data.Results:The native T1 values for the healthy group in our 3-Tesla MRI system was 1186.47 ± 45.67 ms. The mean T1 values of the groups acute myocarditis (1418.68 ± 8.62 ms), HCM (1355.86 ± 44.67 ms), nonischemic DCM (1341.31 ± 41.48 ms), and RCM due to amyloidosis (1370.37 ± 90.14 ms) were significantly higher (P = 0.0005) than that of the healthy control group.Conclusion:Native myocardial T1 mapping is a promising tool for differentiating between healthy and diffuse myocardial disease groups.

Potential of Liver T1 Mapping for the Detection of Fontan-associated Liver Disease in Adults.

Purpose:The native T1 value at 3T MRI is a sensitive marker for diffuse fibrosis or damage in various organs including the heart, liver, and pancreas. Despite the fact that Fontan-associated liver disease (FALD) is a crucial issue in adults with Fontan circulation, there are only a few studies with liver T1 mapping in children and adolescents. We investigated the potential of the liver native T1 mapping in detecting FALD in adult patients.Methods:We prospectively enrolled 16 consecutive adults with Fontan circulation (age 31.3 ± 8.5 years), who were in New York Heart Association Functional class II–IV. Twenty with tetralogy of Fallot (TOF), and 20 age-matched controls also underwent cardiac magnetic resonance (CMR) imaging at 3T. Myocardial T1 mapping with a Modified Look-Locker Inversion recovery sequence was applied to liver T1 mapping. Patients in the Fontan group underwent the right heart catheter and liver function tests, including those for fibrotic markers.Results:Liver native T1 values in the Fontan group were significantly higher than that in TOF and controls (P < 0.001). In the Fontan group, the liver native T1 value was significantly correlated with age, γ -glutamyltransferase, model for end-stage liver disease XI score, and albumin-bilirubin score (P = 0.01, 0.01, 0.044, 0.001). However, it demonstrated no correlation with central venous pressure, pulmonary vessel resistance, or fibrotic markers.Conclusion:Liver native T1 value derived from CMR may be a non-invasive adjunctive and/or screening marker to detect FALD.

Myocardial Native T1 Predicts Load-Independent Left Ventricular Chamber Stiffness In Patients With HFpEF

ObjectivesThis study sought to evaluate the potential of cardiac magnetic resonance T1 mapping to detect load-independent left ventricular (LV) chamber stiffness by histological confirmation. BackgroundAccurate noninvasive diagnosis of LV diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF) remains challenging. MethodsNineteen HFpEF patients (14 female, 65 ± 16 years of age) without primary cardiomyopathy were prospectively enrolled. Cine, late gadolinium enhancement cardiac magnetic resonance, and triple-slice T1 mapping using a modified Look-Locker inversion recovery sequence were performed at 3-T. Extracellular volume (ECV) was quantified from pre- and post-contrast T1 values of the blood and myocardium with hematocrit correction. LV stiffness constant (beta) was assessed by calculating the slope of the end-diastolic pressure–volume relationship curve during vena cava occlusion. Biopsy samples were used for quantification of collagen volume fraction (CVF) and myocardial cell size. ResultsSix patients showed focal scar on late gadolinium enhancement. There was no significant difference in histological CVF between patients with and without focal myocardial scarring (p = 0.2). Septal ECV rather than native T1 was a better surrogate marker for detecting histological CVF (r = 0.54; p = 0.02, and r = 0.44; p = 0.06, respectively). Global native T1 and ECV, but not native T1 and ECV in the septal myocardium, correlated well with the beta of passive LV stiffness, and had similar ability for predicting LV stiffness to histological CVF (r = 0.54, 0.50, 0.53, all p < 0.05, respectively). When the beta ≥0.054 was considered as moderately increased LV stiffness, global native T1 ≥1,362 ms provided 88% sensitivity and 64% specificity with the C-statistic of 0.81 (95% confidence interval: 0.56 to 0.95). ConclusionsMyocardial native T1 provides comparable ability in predicting LV stiffness to ECV and histological CVF and may be useful for monitoring patients with HFpEF who have renal dysfunction, allergy to gadolinium, or wheezing that can simulate asthma. Our feasibility study shows the potential of native T1 to allow for insight of heterogeneous pathophysiology and better risk stratification of HFpEF.

Correlation of Pancreatic T1 Values Using Modified Look-Locker Inversion Recovery Sequence (MOLLI) with Pancreatic Exocrine and Endocrine Function.

Quantifying myocardial T1 values has been useful for detecting and characterizing fibrotic appearance in myocardial infarction, focal scars, and non-ischemic cardiomyopathies. Since pancreatic exocrine function decreases with chronic pancreatic fibrosis advancement, this study examined the correlation between pancreatic T1 values and pancreatic exocrine and endocrine insufficiency. Methods: Thirty-two patients underwent abdominal contrast-enhanced MRI in our department between October 2017 and February 2019. We evaluated the T1 values of the pancreas using a modified Look-Locker inversion recovery sequence (MOLLI), pancreatic exocrine insufficiency (PEI) by fecal elastase 1 (FE1) values, and pancreatic endocrine insufficiency using fasting insulin and blood glucose levels to calculate the HOMA-β. This trial is registered in the UMIN Clinical Trials Registry as UMIN 000030067. Results: The median cohort (9 males and 23 females) age was 71 (range: 49–84) years. Eighteen patients had pancreatic cysts, three had alcohol-induced chronic pancreatitis, three had pancreatic cancer, and eight possessed other pancreatic features (two patients each with autoimmune pancreatitis, acute pancreatitis, or a bile duct tumor, one with idiopathic chronic pancreatitis, and one healthy control with negative findings). The median pancreatic T1 value measured by the MOLLI was 857.5 ms (597–2569). A significant negative correlation was found between the T1 mapping and FE1 values (r = 0.69, p < 0.01), with none for the T1 with HOMA-β or serum albumin, triglycerides, or body mass index. Conclusions: the pancreatic T1 values correlated significantly with pancreatic exocrine function and might be useful in PEI diagnosis.

Evaluation of T1 relaxation time in prostate cancer and benign prostate tissue using a Modified Look-Locker inversion recovery sequence

Purpose of this study was to evaluate the diagnostic performance of T1 relaxation time (T1) for differentiating prostate cancer (PCa) from benign tissue as well as high- from low-grade PCa. Twenty-three patients with suspicion for PCa were included in this prospective study. 3 T MRI including a Modified Look-Locker inversion recovery sequence was acquired. Subsequent targeted and systematic prostate biopsy served as a reference standard. T1 and apparent diffusion coefficient (ADC) value in PCa and reference regions without malignancy as well as high- and low-grade PCa were compared using the Mann-Whitney U test. The performance of T1, ADC value, and a combination of both to differentiate PCa and reference regions was assessed by receiver operating characteristic (ROC) analysis. T1 and ADC value were lower in PCa compared to reference regions in the peripheral and transition zone (p < 0.001). ROC analysis revealed high AUCs for T1 (0.92; 95%-CI, 0.87–0.98) and ADC value (0.97; 95%-CI, 0.94 to 1.0) when differentiating PCa and reference regions. A combination of T1 and ADC value yielded an even higher AUC. The difference was statistically significant comparing it to the AUC for ADC value alone (p = 0.02). No significant differences were found between high- and low-grade PCa for T1 (p = 0.31) and ADC value (p = 0.8). T1 relaxation time differs significantly between PCa and benign prostate tissue with lower T1 in PCa. It could represent an imaging biomarker for PCa.

Temporal registration: a new approach to manage the incomplete recovery of the longitudinal magnetization in the Modified Look-Locker Inversion Recovery sequence (MOLLI) for T1 mapping of the heart.

To correct with post-processing effects of incomplete recovery of the longitudinal magnetization before a new inversion pulse in the Modified Look-Locker Inversion recovery sequence (MOLLI) sequence. We model such effects as a temporal shift ([Formula: see text]) of the signal of the Look-Locker block following next inversion pulses. After using the following equation [Formula: see text], a temporal registration of [Formula: see text] is applied to the signal of the affected block to adjust the sampling time of the recovery signal and correct the underlying effect on quantitative T1. To test our approach, simulations, phantoms, and five volunteers' data were used while applying different MOLLI sampling schemes at different heart rates and compared to the reference three-parameter fit. The temporal registration of the affected signals allows to reach higher accuracy on long T1 when compared to the reference three parameters fit (10.15 vs 22.12% for T1 = 1785ms; 8.22 vs 14.65% for T1 = 1278ms), and lower average variation in case of rest-period deletion (62 vs 231ms). The proposed approach leads to more accurate T1 in case of incomplete recovery. It is less sensitive to parameters affecting the recovery such as the rest period or the sampling scheme; and, therefore, supports multi-center studies with different MOLLI protocols.

Potential Value of Native T1 Mapping in Symptomatic Adults with Congenital Heart Disease: A Preliminary Study of 3.0 Tesla Cardiac Magnetic Resonance Imaging.

The native T1 value at 3.0 Tesla is a sensitive marker of diffuse myocardial damage. We evaluated the clinical usefulness of native T1 mapping in symptomatic adults with congenital heart disease (CHD), particularly in the systemic right ventricle (RV). Prospectively, 45 consecutive symptomatic adults with CHD were enrolled: 20 with systemic RV and 25 with tetralogy of Fallot underwent cardiac magnetic resonance (CMR) imaging at 3.0 Tesla. The Modified Look-Locker Inversion recovery sequence was used for T1 mapping. Cardiovascular events in the systemic RV were defined as heart failure and tachyarrhythmia. Brain natriuretic peptide (BNP) and indexed systemic ventricular end-diastolic volume were significantly higher in the systemic RV group. The native T1 value and extracellular volume (ECV) of the septal and lateral walls were higher in the systemic RV group, suggesting high impairment of the myocardium in the systemic RV group. There was a strong correlation between the native T1 value and ECV of the septum (r = 0.58, P = 0.03) and lateral wall (r = 0.56, P = 0.046) in the systemic RV group. Seven patients with systemic RV had cardiovascular events. In univariate logistic regression analysis, BNP and native T1 values of the insertion point were important for predicting cardiovascular events. The native T1 value at 3.0 Tesla may be a sensitive, contrast-free, and non-invasive adjunct marker of myocardial damage in CHD and predictive of cardiovascular events in the systemic RV.

98. Patient-specific estimation of the red marrow extracellular fluid fraction for improving the accuracy of red marrow dosimetry in radioimmunotherpy

Purpose The red marrow (RM) is the dose-limiting organ in radioimmunotherapy. The RM dosimetry is usually calculated by radioactivity concentrations of blood samples: RM kinetics is derived multiplying the blood kinetics by the “red marrow-to-blood activity concentration ratio” (RMBLR), calculated by patient-specific RM extracellular fluid fraction (RMECFF) and hematocrit (HCT) i.e., RMBLR = RMECFF/(1-HCT) [ [1] Sgouros G. Bone marrow dosimetry for radioimmunotherapy: theoretical considerations. J Nucl Med. 1993; 34: 689-694 PubMed Google Scholar ]. Preliminarily, the possible use of Contrast-Enhanced Magnetic Resonance Imaging (CEMRI) for estimating the patient-specific RMECFF was here investigated. Methods 9 patients (5 men, 4 women) studied with CEMRI for cardiac disorders were examined. Pre- and post-contrast T1 mapping by MOLLI (modified Look-Locker inversion-recovery) sequences was performed, and the extracellular volume fraction (ECV) map was calculated by a novel method - based on a Fast Non-linear Least Squares (FNLS) algorithm. The mean ECV of the spongiosa volume (SV) inside the dorsal vertebra at the heart level was obtained as mean value in a region-of-interest (ROI) lying wholly within the SV. Results The mean ECV of the SV was (mean[range]): 29.9[24.0–35.3]%. Considering the ECV as a preliminary estimation of the RMECFF, and accounting also for the patient HCT values (ranging from 0.340 up to 0.499), the mean RMBLR was 0.430[0.316–0.546], in a good agreement with the range of 0.2–0.4 generally reported in the literature (even though values sometimes well outside this range were also observed) [ [1] Sgouros G. Bone marrow dosimetry for radioimmunotherapy: theoretical considerations. J Nucl Med. 1993; 34: 689-694 PubMed Google Scholar ]. Conclusion The CEMRI is accurate and very promising for patient-specific RMECFF estimations. Accuracy improvements by MOLLI sequence optimisation, or correction for the presence of trabecular bone and fatty tissue into the SV, are currently under investigation. The red marrow (RM) is the dose-limiting organ in radioimmunotherapy. The RM dosimetry is usually calculated by radioactivity concentrations of blood samples: RM kinetics is derived multiplying the blood kinetics by the “red marrow-to-blood activity concentration ratio” (RMBLR), calculated by patient-specific RM extracellular fluid fraction (RMECFF) and hematocrit (HCT) i.e., RMBLR = RMECFF/(1-HCT) [ [1] Sgouros G. Bone marrow dosimetry for radioimmunotherapy: theoretical considerations. J Nucl Med. 1993; 34: 689-694 PubMed Google Scholar ]. Preliminarily, the possible use of Contrast-Enhanced Magnetic Resonance Imaging (CEMRI) for estimating the patient-specific RMECFF was here investigated. 9 patients (5 men, 4 women) studied with CEMRI for cardiac disorders were examined. Pre- and post-contrast T1 mapping by MOLLI (modified Look-Locker inversion-recovery) sequences was performed, and the extracellular volume fraction (ECV) map was calculated by a novel method - based on a Fast Non-linear Least Squares (FNLS) algorithm. The mean ECV of the spongiosa volume (SV) inside the dorsal vertebra at the heart level was obtained as mean value in a region-of-interest (ROI) lying wholly within the SV. The mean ECV of the SV was (mean[range]): 29.9[24.0–35.3]%. Considering the ECV as a preliminary estimation of the RMECFF, and accounting also for the patient HCT values (ranging from 0.340 up to 0.499), the mean RMBLR was 0.430[0.316–0.546], in a good agreement with the range of 0.2–0.4 generally reported in the literature (even though values sometimes well outside this range were also observed) [ [1] Sgouros G. Bone marrow dosimetry for radioimmunotherapy: theoretical considerations. J Nucl Med. 1993; 34: 689-694 PubMed Google Scholar ]. The CEMRI is accurate and very promising for patient-specific RMECFF estimations. Accuracy improvements by MOLLI sequence optimisation, or correction for the presence of trabecular bone and fatty tissue into the SV, are currently under investigation.

Left ventricular myocardial T1 mapping and strain analysis evaluate cardiac abnormality in hypothyroidism.

Cardiovascular Magnetic Resonance (CMR)-based T1 mapping and Heart Deformation Analysis (CMR-HDA) can assess the myocardial tissue characteristic and strain of cardiomyopathy. Whether they can assess cardiac abnormality of hypothyroidism (HT) is unknown. We aim to analysis left ventricular (LV) T1 values and strain of patients with overt HT (OHT) and subclinical HT (SHT) with CMR-based T1 mapping and HDA. This study prospectively included 32 OHT patients, 23 SHT patients and 27 healthy controls who underwent CMR. LV T1 mapping was obtained with a Modified Look-Locker Inversion Recovery sequence while LV circumferential strain (LVCS) and radial strain (LVRS), LV longitudinal strain (LVLS) were respectively analyzed on the short-axial and four-chamber cines with HDA. LV Eject Fraction among three groups were similar (p = 0.676). LV myocardial T1 correlated with LVCS (r = 0.734, p < 0.001) and LVRS (r = - 0.340, p = 0.011). LV myocardial T1 of OHT patients significantly increased in comparison with SHT patients (t = 5.403, p < 0.001) and normal controls (t = 10.197, p < 0.001), meanwhile, LV myocardial T1 of SHT patients were higher than that of controls (t = 2.629, p = 0.013). Compared with SHT patients (t = 1.925, p = 0.031) and normal controls (t = 2.875, p = 0.006), LVCS of OHT patients reduced while LVCS of SHT patients were lower than that of normal controls (t = 2.451, p = 0.020). LVRS of SHT patients were higher than OHT patients (t = 2.778, p = 0.008), but comparable to normal controls (t = 1.134, p = 0.266). LVLS of SHT and OHT significantly impaired in comparison with normal control. The increased LV myocardial T1 value and reduced strain were found in HT. CMR-based LV myocardial T1 and stain analysis are useful to evaluate myocardial tissue characteristic and mechanics in both overt and subclinical hypothyroidism.

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

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