REPAIRit: Improving Myocardial Nulling and Ghosting Artifacts of 3D Navigator-Gated Late Gadolinium Enhancement Imaging During Arrhythmia.

BACKGROUND: Cardiac 3D navigator-gated late gadolinium enhancement (LGE) imaging is important for assessment of left atrial fibrosis, but the image quality is often degraded due to arrhythmia. PURPOSE: To investigate a novel 3D LGE sequence with improved myocardial nulling and reduced ghosting artifacts during arrhythmia. STUDY TYPE: Prospective. POPULATION: Arrhythmia patients (n = 14). SEQUENCE: The proposed technique, REPAIRit (Regrowth Equalization Pulse for Arrhythmias in Inversion Recovery with automatic inversion time calculation), inserts a saturation pulse with a dynamic flip angle into the 3D LGE sequence to minimize arrhythmia-induced signal fluctuations. Using ShMOLLI (shortened modified Look-Locker imaging) to estimate myocardial T1 , REPAIRit automatically calculates the optimal inversion time (TI) based on Bloch equations. ASSESSMENT: REPAIRit LGE and the standard LGE were compared with simulations, phantom imaging, and patient studies. Patient images were assessed quantitatively, based on ghost-to-noise ratio (GNR), blood signal-to-noise ratio (SNRb), myocardial signal-to-noise ratio (SNRm), and blood-to-myocardium contrast-to-noise ratio (CNR), and qualitatively on a 4-point scale. Patients were subgrouped based on the presence of arrhythmia to assess the image quality difference. STATISTICAL TESTS: The two LGE sequences were compared by Student's t-test and Wilcoxon signed-rank test. The two patient-subgroups were compared using Welch's t-test and Wilcoxon rank-sum test. RESULTS: In 14 analyzed patients, REPAIRit LGE significantly lowered GNR (1.25 ± 0.41 vs. 1.42 ± 0.42, P = 0.04), reduced SNRm (1.90 ± 0.60 vs. 3.16 ± 1.66, P = 0.01), improved ghosting artifact scores (2.5 ± 0.6 vs. 2.2 ± 0.9, P = 0.03), myocardial nulling scores (2.7 ± 0.5 vs. 2.3 ± 0.7, P = 0.02), and atrial quality scores (2.8 ± 0.3 vs. 2.4 ± 0.8, P = 0.03) compared with the standard LGE. Comparing patients with arrhythmia (n = 6) to those without (n = 8) during the scan, the former had lower left ventricular (LV) myocardial T1 s (430 ± 26 msec vs. 469 ± 39 msec, P = 0.06) but similar blood T1 s (318 ± 55 msec vs. 316 ± 27 msec, P = 0.96), and significantly lower blood SNR (5.2 ± 1.8 vs. 9.2 ± 3.0, P = 0.01) and significantly worse image quality (P = 0.01 for REPAIRit and P = 0.03 for standard). DATA CONCLUSION: REPAIRit improves myocardial nulling and reduces ghosting artifacts of 3D LGE under arrhythmia. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:688-699.

Reverse double inversion-recovery: Improving motion robustness of cardiac T2 -weighted dark-blood turbo spin-echo sequence.

BACKGROUND: Cardiac dark-blood turbo spin-echo (TSE) imaging is sensitive to through-plane motion, resulting in myocardial signal reduction. PURPOSE: To propose and validate reverse double inversion-recovery (RDIR)-a dark-blood preparation with improved motion robustness for the cardiac dark-blood TSE sequence. STUDY TYPE: Prospective. POPULATION: Healthy volunteers (n = 10) and patients (n = 20). FIELD STRENGTH: 1.5T (healthy volunteers) and 3T (patients). ASSESSMENT: Compared to double inversion recovery (DIR), RDIR swaps the two inversion pulses in time and places the slice-selective 180° in late-diastole of the previous cardiac cycle to minimize slice misregistration. RDIR and DIR were performed in the same left-ventricular basal short-axis slice. Healthy subjects were imaged with two preparation slice thicknesses, 110% and 200%, while patients were imaged using a 200% slice thickness only. Images were assessed quantitatively, by measuring the myocardial signal heterogeneity and the extent of dropout, and also qualitatively on a 5-point scale. STATISTICAL TESTS: Quantitative and qualitative data were assessed with Student's t-test and Wilcoxon signed-rank test, respectively. RESULTS: In healthy subjects, RDIR with 110% slice thickness significantly reduced signal heterogeneity in both the left ventricle (LV) and right ventricle (RV) (LV: P = 0.006, RV: P < 0.0001) and the extent of RV dropout (P < 0.0001), while RDIR with 200% slice thickness significantly reduced RV signal heterogeneity (P = 0.001) and the extent of RV dropout (P = 0.0002). In patients, RDIR significantly reduced RV myocardial signal heterogeneity (0.31 vs. 0.43; P = 0.003) and the extent of RV dropout (24% vs. 46%; P = 0.0005). LV signal heterogeneity exhibited a trend towards improvement with RDIR (0.12 vs. 0.16; P = 0.06). Qualitative evaluation showed a significant improvement of LV and RV visualization in RDIR compared to DIR (LV: P = 0.04, RV: P = 0.0007) and a significantly improved overall image quality (P = 0.03). DATA CONCLUSION: RDIR TSE is less sensitive to through-plane motion, potentiating increased clinical utility for black-blood TSE. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1498-1508.

Left atrial fibrosis correlates with extent of left ventricular myocardial delayed enhancement and left ventricular strain in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is associated with increased left ventricular (LV) mass, decreased myocardial strain, and the presence of LV fibrosis and scar. The relationship between LV scar and fibrosis with left atrial (LA) fibrosis in the setting of HCM has not been examined. The purpose of this study is to demonstrate a correlation between the degree of LA fibrosis and LV parameters in subjects with HCM. Twenty-eight subjects with HCM were imaged on a 1.5T MRI scanner with cine, LV and LA late gadolinium enhancement (LGE) sequences. LA LGE and LA measurements were correlated with LV measurements of volumes, mass, strain, and LGE. Other clinical conditions and medication usage were also examined and evaluated for correlation with LA and LV parameters. LV LGE was identified in 24 (86%) of the cases and LA LGE was identified in all of the cases. Extent of LA fibrosis significantly correlated with percent LV LGE (r = 0.64, p = 0.001), but not with indexed LV mass or maximum wall thickness. Extent of LA fibrosis also moderately correlated with decreased LV global strain (radial, r = - 0.50, p = 0.013; circumferential, r = 0.47, p = 0.02; longitudinal, r = 0.52, p = 0.013). Increased LA systolic volume correlated moderately with LV end diastolic volume (r = 0.50, p = 0.006). Patients on therapy with Renin-Angiotensin-Aldosterone System (RAAS) Inhibition had significantly less LA LGE compared to those without (18.6% vs 10.8%, p = 0.023). LA fibrosis, as measured by LGE, is prevalent in HCM and is correlated with LV LGE. The correlation between LA and LV LGE might suggest either that LA fibrosis is a consequence of LV remodeling, or that LA and LV fibrosis are both manifestations of the same cardiomyopathic process. Further study is warranted to determine the causality of LA scar in this population.

Clinical characteristics and four-year outcomes of patients in the Rhode Island Takotsubo Cardiomyopathy Registry.

The aim was to establish a registry of patients with a diagnosis of Takotsubo cardiomyopathy (TC) to help learn more about the characteristics, treatment strategies, and natural history of this disease. Data for patients with TC diagnosed from July 2004 to April 2008 at 2 major hospitals in Rhode Island were obtained. A data set was created that included baseline demographics and characteristics, hospital, course, and clinical outcomes. TC was diagnosed in 70 patients during the study period. Postmenopausal women comprised 95% of the cohort. Six patients presented with cardiogenic shock, 9 required intubation, 3 experienced sustained ventricular arrhythmias, and 1 patient died of cardiac causes. Average ejection fraction was 37% at cardiac catheterization. Troponin-I was increased in all except 1 patient. Follow-up echocardiography showed full recovery of wall motion abnormalities, with an average ejection fraction of 59%. Most patients were treated using standard cardiovascular medications for acute coronary syndrome, and 43% were discharged on warfarin therapy because of severe apical wall motion abnormalities. Univariate analysis suggested that long-term use of angiotensin-converting enzyme inhibitors before the onset of TC was protective against cardiogenic shock, sustained ventricular arrhythmia, and death. Consecutive cases grouped into different seasons showed a statistically significant spike in the occurrence of TC during the summer months. In conclusion, the acute phase of this condition may lead to critical illness and death, and use of an angiotensin-converting enzyme inhibitor may have a protective effect. Overall long-term prognosis and recovery of left ventricular function were excellent.