Association between myocardial hypoxia and fibrosis in hypertrophic cardiomyopathy: analysis by T2* BOLD and T1 mapping MRI.

OBJECTIVES: We assessed whether an association exists between myocardial oxygenation and myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM), using blood-oxygen-level-dependent (BOLD) T2* cardiac magnetic resonance imaging (T2*-CMR) and T1 mapping. METHODS: T1 mapping and T2*-CMR data were collected from 55 HCM patients using a 3-T MR and were prospectively analyzed. T2*-CMR was conducted using the black blood, breath-hold, multi-echo, and gradient echo sequence. Over 10 min, inhalation of oxygen at the flow rate of 10 L/min, T2* for mid-septum was measured following room-air and oxygen inhalation, and ΔT2* ratio (T2*oxy-T2*air/T2*air, %) was calculated. During pre- and post-gadolinium enhancement, native T1 (ms) and extracellular volume fractions (ECV, %) were calculated at sites same as the T2* measurement. Hypoxia was defined as the segment with an absolute value of the ΔT2* ratio ≥ 10%. RESULTS: ΔT2* ratio was significantly higher for segments with native T1 ≥ 1290 ms than those with native T1 < 1290 ms (21 ± 32% vs. 8 ± 6%, p = 0.005). ΔT2* ratio was also significantly higher for segments with ECV ≥ 28% than those with ECV < 28% (21 ± 32% vs. 8 ± 8%, p = 0.0003). ROC curve analysis revealed that ΔT2* ratio could detect segments with native T1 ≥ 1290 ms and ECV ≥ 28% and c-statistics of 0.72 and 0.79. According to the multivariate logistic regression analysis results, ECV is an independent factor in hypoxia (odds ratio, 1.47; 95% confidence interval, 1.02-2.13; p < 0.05). CONCLUSIONS: Analysis of BOLD T2*-CMR and T1 mapping revealed that ECV is strongly associated with ΔT2* ratio, suggesting that the onset of myocardial fibrosis is related to hypoxia in HCM patients. TRIAL REGISTRATION: Our study was approved by the ethics committee of our institute (#4036, registered on 21 July 2016) KEY POINTS: • Analysis of ΔT2* ratio and ECV with BOLD-T2* and T1 mapping revealed a strong association between myocardial fibrosis and hypoxia in HCM patients.

Detectability of pulmonary nodules on chest radiographs: bone suppression versus standard technique with single versus dual monitors for visualization.

PURPOSE: To evaluate the diagnostic accuracy of bone suppression imaging (BSI) in the detection of pulmonary nodules on chest radiographs (CXRs) and the effect of visualization method (single or dual monitors) on diagnostic accuracy. MATERIALS AND METHODS: Ten observers interpreted the CXRs of 100 patients: 50 with a T1 lung cancer nodule and 50 without nodules. Each standard CXR was first read alone and then in combination with the corresponding BSI. Two sessions of viewing were conducted: (1) the standard CXR and BSI were placed side by side on dual monitors and (2) both images were shown on the same monitor in alternation. The nodule location, confidence level, and interpretation time were recorded and analyzed statistically. RESULTS: When BSI was added, the area under the receiver operating characteristic curve (AUC) improved with dual monitors and a single monitor. The AUC was not significantly different between the dual-monitor and single-monitor sessions; however, the specificity with BSI and dual monitors decreased. The total interpretation time was significantly shorter with a single monitor than with dual monitors. CONCLUSIONS: The use of BSI improved detectability of T1 lung cancer nodules on CXRs; however, specificity and reading time were affected by the visualization method.

Liver Strain Using Feature Tracking of Cine Cardiac Magnetic Resonance Imaging: Assessment of Liver Dysfunction in Patients with Fontan Circulation and Tetralogy of Fallot.

We propose a novel method to quantify pulsatile liver deformation using the feature tracking method of cardiac cine magnetic resonance imaging (MRI) and investigate its association with liver dysfunction in long-term postoperative patients after Fontan and intracardiac repair for the tetralogy of Fallot (TOF). Standard cine MRI which was previously performed for cardiac evaluation of 85 patients who underwent Fontan operation (mean age, 22.9 years), 43 patients with TOF (mean age, 34.6 years), and 32 healthy controls (mean age, 42.3 years) were retrospectively analyzed. Pulsatile liver deformation in the craniocaudal direction was calculated using the feature tracking method of cardiac cine imaging derived from cine-balanced turbo field-echo sequences performed on a 1.5 Tesla MR scanner, and was defined as liver strain. The liver strain was compared across the three patient groups using one-way analysis of variance. Liver dysfunction by a liver strain were compared using the Mann-Whitney U test. Liver strain for patients who underwent Fontan operation and TOF patients was significantly lower than controls (Fontan, 13.3 ± 6.5%; TOF, 15.0 ± 11.2%; controls, 23.1 ± 10.2%, p < 0.0001). In Fontan and TOF patients, MELD score was significantly greater for patients with a liver strain < 15% than those with values > 15% (5.9 ± 5.8 vs. 2.9 ± 2.9, p < 0.001). Lower liver strain values were found in adolescent and adult patients after Fontan operation and TOF, and correlates with the severity of liver injury, expressed as MELD score. Our method can evaluate hepatic function in adult congenital heart disease, together with the assessment of cardiac function.

Low-dose radioiodine therapy for patients with intermediate- to high-risk differentiated thyroid cancer.

OBJECTIVE: The efficacy of low-dose radioiodine therapy (RIT) for intermediate-risk or high-risk differentiated thyroid cancer (DTC) patients is controversial. Because of the country's shortage of medical facilities for RIT, 1110-MBq RIT for higher risk DTC patients has been performed on an outpatient basis since 2010 in Japan. Herein, we addressed this issue and attempted to determine prognostic factors for the prediction of RIT outcomes. METHODS: We retrospectively analyzed the cases of 119 patients with papillary thyroid cancer who underwent their first RIT with 1110 MBq radioactive iodine (RAI) following a total thyroidectomy, including 65 (54.6%) intermediate-risk and 54 (45.4%) high-risk patients (according to Japan's 2018 clinical practical guidelines for thyroid tumors). Successful ablation was defined when a negative I-131 whole-body scan and thyroglobulin (Tg) < 2 ng/mL were obtained at a diagnostic scan performed 148-560 days (median 261 days) after the first RIT. RESULTS: The overall ablation success rate was 23.4%. Although the ablation success rates of each pretreatment protocol [recombinant human thyroid stimulating hormone and thyroid hormone withdrawal (THW)] did not differ significantly, THW tended to result in a higher success rate than rhTSH. The Tg level at RIT was the only independent powerful predictive factor for successful ablation. The best cut-off value of Tg for predicting unsuccessful ablation was 9 ng/mL. CONCLUSIONS: The ablation success rate was much lower than those of earlier studies; the most plausible reason would be that higher risk DTC patients were included in this study. The low-dose RIT routinely performed in Japan might be inadequate for the achievement of successful ablation. At least for patients with Tg > 9 ng/mL at the first RIT, a higher dose of RAI is recommended.

FDG PET/CT Findings of Ectopic Pituitary Adenoma.

A 72-year-old woman had undergone a right mastectomy for breast cancer 3 years earlier. PET/CT revealed a tumor with bony destruction of the skull base and FDG accumulation (SUVmax, 7.86). MRI showed the well-circumscribed tumor in the sphenoid sinus. The possibility of bone metastasis could not be denied. Tumor removal surgery was performed; the tumor was separate from the normal pituitary gland, and an ACTH-producing ectopic pituitary adenoma was diagnosed pathologically.

Global strain and dyssynchrony of the single ventricle predict adverse cardiac events after the Fontan procedure: Analysis using feature-tracking cine magnetic resonance imaging.

BACKGROUND: The aim of this study was to determine whether major adverse cardiac events (MACE) during the late phase of the Fontan procedure could be predicted by strain measurements of single ventricles using cardiac magnetic resonance imaging with feature tracking (CMR-FT). METHODS: One hundred adolescent patients who underwent the Fontan procedure (mean age, 21 years) were examined retrospectively with CMR-FT to assess the systemic single-ventricle function. Vertical long-axis cine imaging was divided into six myocardial segments. Global longitudinal strain (GLS) was determined by averaging the peak strain values of each of the six segments. The dyssynchrony index was defined as the standard deviation of the time to peak strain for six segments. The primary outcome was MACE, defined as cardiac death and unscheduled hospitalization. RESULTS: MACE occurred in 18 patients during a mean follow-up of 62 months. According to the multivariate logistic regression analysis results for potential predictor variables, GLS and the dyssynchrony index are independent predictors of MACE. Patients with GLS ≥11.8% had significantly higher MACE-free rates than did those with GLS <11.8% [log-rank value, 14.15; p = 0.0002; hazard ratio, 6.82; 95% confidence interval (CI), 2.51-18.56]. Patients with a dyssynchrony index <63.5 ms had significantly higher MACE-free rates than did those with dyssynchrony index ≥63.5 ms (log-rank value, 28.17; p < 0.0001; hazard ratio, 21.69; 95% CI, 6.96-67.56). CONCLUSION: GLS and the dyssynchrony index found using CMR-FT are independent predictors of MACE for adolescent patients after the Fontan procedure and provide information regarding risk stratification beyond clinical parameters and biomarkers.

Feature-Tracking MRI Fractal Analysis of Right Ventricular Remodeling in Adults with Congenitally Corrected Transposition of the Great Arteries.

PURPOSE: To assess a recently available technique for quantification of right ventricular (RV) trabeculae that is based on fractal analysis performed by using cardiac MRI feature tracking, in patients with congenitally corrected transposition of the great arteries (cc-TGA). MATERIALS AND METHODS: A total of 19 patients (eight men, 11 women; mean age, 35 years ± 10 [standard deviation]) with consecutive cc-TGA who underwent cardiac MRI were enrolled in the study. For analysis, patients were divided into two groups: six patients (four men, two women; mean age, 34 years ± 14) with an end-systolic RV volume index higher than 72 mL/m2 (indicative of adverse RV remodeling) and 13 patients (four men, nine women; mean age, 36 years ± 9) in whom this index was lower than or equal to 72 mL/m2 (indicative of adapted RV). The following outcomes were quantified in the midsection of the RV: fractional fractal dimension (FD) and diastolic FD, circumferential strain, and radial strain. Receiver operating characteristic (ROC) analysis was performed to determine the cutoff FD values for the detection of adverse RV remodeling. Correlations among fractional FD, diastolic FD, circumferential strain, and radial strain were calculated by using Pearson correlation coefficient (r) analysis. RESULTS: The following ROC values were identified for fractional and diastolic FD: cutoff, 0.09 and 1.39, respectively; area under the ROC curve, 0.95 and 0.68, respectively; sensitivity, 1.00 and 0.33, respectively; and specificity, 0.92 and 1.00, respectively. Fractional FD correlated with circumferential strain and radial strain (r = -0.70 and 0.69, respectively; P < .01), as did diastolic FD (r = 0.37 and -0.38, respectively; P < .05). CONCLUSION: The fractional FD derived from cardiac MRI feature-tracking analysis correlates with adverse RV remodeling, including a changed strain pattern and trabeculae, in patients with cc-TGA.© RSNA, 2019.

Discrepancy between significant fibrosis and active inflammation in patients with cardiac sarcoidosis: combined and image fusion analysis of cardiac magnetic resonance and 18F fluorodeoxyglucose positron emission tomography.

BACKGROUND: Diagnosis and evaluation of cardiac sarcoidosis (CS) are mainly based on the combined use of cardiac magnetic resonance imaging (CMR) and 18F fludeoxyglucose positron emission tomography (FDG). Though these modalities can detect the pathological feature of the disease, combined assessment has not been fully examined. Multimodality image fusion is known to be useful for further comprehension, while most image interpretation is performed with a side by side comparison in clinical routine. We investigated the similarity and discrepancy of active inflammation, regional fibrosis, and wall function by image fusion of CMR and FDG. METHODS: Patients with CS who underwent both CMR and FDG were retrospectively enrolled. The extent of myocardial late gadolinium enhancement (LGE) in left ventricle (LGE volume), cardiac function, and volume (left ventricular ejection fraction, LVEF; end-diastolic volume, EDV) was measured from CMR. The FDG uptake in whole myocardium (whole SUVmax), cardiac metabolic volume (CMV), and cardiac metabolic activity (CMA) was calculated from FDG. CMR and FDG were fused and divided into AHA 17 model for segmental analysis. Wall motion, the magnitude of LGE in myocardial wall (LGE%wall), and corresponding FDG uptake (segmental SUVmax) were analyzed. RESULTS: Forty-one patients were retrospectively enrolled. In patients with FDG uptake, LVEF inversely correlated to LGE volume and positively correlated to SUVmax (r = - 0.56, p < 0.0001, and r = 0.08, p = 0.048, respectively). Discrepancy between LGE volume and CMV showed a significant positive correlation to whole SUVmax and CMA (r = 0.49, p < 0.0001, and r = 0.96, p < 0.0001, respectively). In image fusion analysis, segmental SUVmax showed a significant inverse correlation to LGE%wall (Spearman's rank correlation coefficient; r = - 0.15, p = 0.008). LGE%wall also showed significant inverse correlation to wall motion (r = - 0.13, p = 0.0011). CONCLUSION: Combined and fusion analysis with CMR and FDG demonstrated the discrepancy of myocardial inflammation and extensive fibrosis. Active inflammation was present in the earlier stage of myocardial fibrosis and was found to be less in the wall with advanced fibrosis and remodeling. Combined analysis of CMR and FDG can incrementally reclassify the pathological stage of CS.

Prediction of Fontan-Associated Liver Disease Using a Novel Cine Magnetic Resonance Imaging "Vortex Flow Map" in the Right Atrium.

BACKGROUND: Long-term hepatic dysfunction is an increasingly recognized complication of the Fontan operation for univentricular hearts. The purpose of this study was to determine whether Fontan-associated liver disease (FALD) could be predicted by flow dynamics in the right atrium (RA) of Fontan circulation.Methods and Results:Cardiac MRI and the serum levels of total bilirubin (TBil) and hyaluronic acid (HA) were analyzed in 36 patients who underwent an atriopulmonary connection type of Fontan operation. The mean follow-up period was 53 months. Three views (axial, coronal, and sagittal) of the cine images were scanned for the maximum cross-section of the RA obtained with1.5-Tesla scanner. We developed a "vortex flow map" to demonstrate the ratio of the circumferential voxel movement in each phase to the total movement throughout a cardiac cycle towards the center of the RA. The maximum ratio was used as the magnitude of vortex flow (MVF%) in the 3 views of the RA cine imaging. Patients with coronal MVF ≥13.6% had significantly lower free rates of TBil ≥1.8 mg/dL than those with coronal MVF <13.6% (log-rank value=4.50; P<0.05; hazard ratio=4.54). Patients with sagittal MVF ≥14.0% had significantly lower free rates of HA ≥50 ng/mL than those with coronal MVF <14.0% (log-rank value=4.40; P<0.05; hazard ratio=4.12). CONCLUSIONS: A reduced vortex flow in the RA during the late phase of the Fontan operation was associated with the development of FALD. MVF can be used as an imaging biomarker to predict FALD.

Vortex Flow in the Right Atrium Surrogates Supraventricular Arrhythmia and Thrombus After Atriopulmonary Connection-Type Fontan Operation: Vortex Flow Analysis Using Conventional Cine Magnetic Resonance Imaging.

We developed a novel imaging technique, designated as vortex flow (VF) mapping, which presents a vortex flow visually on conventional two-dimensional (2D) cine MRI. Using it, we assessed circumferential VF patterns and influences on RA thrombus and supraventricular tachycardia (SVT) in AP connection-type Fontan circulation. Retrospectively, we enrolled 27 consecutive patients (25.1 ± 9.2 years) and 7 age-matched controls who underwent cardiac MRI. Conventional cine images acquired using a 1.5-Tesla scanner were scanned for axial and coronal cross section of the RA. We developed "vortex flow mapping" to demonstrate the ratio of the circumferential voxel movement at each phase to the total movement throughout a cardiac cycle towards the RA center. The maximum ratio was used as a magnitude of vortex flow (MVF%) in RA cine imaging. We also measured percentages of strong and weak VF areas (VFA%). Furthermore, in 10 out of 27, we compared VF between previous CMR (3.8 ± 1.5 years ago) and latest CMR. Of the patients, 15 had cardiovascular complications (Group A); 12 did not (Group B). A transaxial image showed that strong VFA% in Group A was significantly smaller than that in Group B or controls. A coronal view revealed that strong VFA% was also smaller, and weak VFA% was larger in Group A than in Group B or controls (P < 0.05, and P < 0.05). Maximum MVF% in Group A was significantly smaller than in other groups (P < 0.001). Univariate logistic analyses revealed weak VFA% on a coronal image, and serum total bilirubin level as factors affecting cardiovascular complications (Odds ratio 1.14 and 66.1, 95% CI 1.004-1.30 and 1.59-2755.6, P values < 0.05 and < 0.05, respectively). Compared to the previous CMR, smaller maximum VMF%, smaller strong VFA%, and larger weak VFA% were identified in the latest CMR. Circumferentially weak VFA% on a coronal image can be one surrogate marker of SVT and thrombus in AP connection-type Fontan circulation. This simple VF assessment is clinically useful to detect blood stagnation.

Reduction of Radiation Exposure Using Dynamic Trace Digital Angiography and Spot Fluoroscopy During Adrenal Venous Sampling.

PURPOSE: To compare radiation exposure of adrenal venous sampling (AVS) using dynamic trace digital angiography (DTDA) and spot fluoroscopy with that using conventional methods. MATERIALS AND METHODS: AVS was performed in 11 patients using DTDA and spot fluoroscopy (Group A) and 11 patients using conventional digital subtraction angiography (DSA) with collimation (Group B). Radiation exposure and image quality of adrenal venography using a five-point scale were compared between the groups. RESULTS: The acquisition dose-area product (DAP) using DTDA and fluoro-DAP using spot fluoroscopy in Group A were lower than those using conventional DSA (5.3 ± 3.7 vs. 29.1 ± 20.1 Gy cm2, p < 0.001) and collimation (33.3 ± 22.9 vs. 59.1 ± 35.7 Gy cm2, p = 0.088) in Group B. The total DAP in Group A was significantly lower than that in Group B (38.6 ± 25.9 vs. 88.2 ± 53.6 Gy cm2, p = 0.006). The peak skin dose for patients and operator radiation exposure in Group A were significantly lower than those in Group B (403 ± 340 vs. 771 ± 416 mGy, p = 0.030, and 17.1 ± 14.8 vs. 36.6 ± 21.7 µSv, p = 0.013). The image quality of DTDA (4.4 ± 0.6) was significantly higher than that of digital angiography (3.8 ± 0.9, p = 0.011) and equivalent to that of DSA (4.3 ± 0.8, p = 0.651). CONCLUSIONS: Radiation exposure during AVS can be reduced by approximately half for both patients and operators by using DTDA and spot fluoroscopy without sacrificing image quality.

Quantification of myocardial oxygenation in heart failure using blood-oxygen-level-dependent T2* magnetic resonance imaging: Comparison with cardiopulmonary exercise test.

PURPOSE: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results. METHODS: Thirty patients with refractory HF who underwent cardiac MRI and CPX test for heart transplantation, and 24 healthy, age-matched volunteers as controls were enrolled. M-T2* imaging was performed using a 3-Tesla and multi-echo gradient-echo sequence. M-T2* was calculated by fitting the signal intensity data for the mid-left ventricular septum to a decay curve. M-T2* was measured under room-air (T2*-air) and after inhalation of oxygen for 10min at a flow rate of 10L/min (T2*-oxy). MO was defined as the difference between the two values (ΔT2*). Changes in M-T2* at the two conditions and ΔT2* between the two groups were compared. Correlation between ΔT2* and CPX results was analyzed using the Pearson coefficient. RESULTS: T2*-oxy was significantly greater than T2*-air in patients with HF (29.9±7.3ms vs. 26.7±6.0ms, p<0.001), whereas no such difference was observed in controls (25.5±4.0ms vs. 25.4±4.4ms). ΔT2* was significantly greater for patients with HF than for controls (3.2±4.5ms vs. -0.1±1.3ms, p<0.001). A significant correlation between ΔT2* and CPX results (peak VO2, r=-0.46, p<0.05; O2 pulse, r=-0.54, p<0.005) was observed. CONCLUSION: ΔT2* is increased T2*-oxy is greater in patients with HF, and is correlated with oxygen metabolism during exercise as measured by the CPX test. Hence, ΔT2* can be used as a surrogate marker of MO instead of CPX test.