Free-breathing pseudo-golden-angle bSSFP cine cardiac MRI for biventricular functional assessment in congenital heart disease.

PURPOSE: To compare standard breath-hold (BH) cine imaging to a radial pseudo-golden-angle free-breathing (FB) technique in congenital heart disease (CHD). METHODS: In this prospective study, short-axis and 4-chamber BH and FB cardiac MRI sequences of 25 participants with CHD acquired at 1.5 Tesla, were quantitatively compared regarding ventricular volumes, function, interventricular septum thickness (IVSD), apparent signal to noise ratio (aSNR), and estimated contrast to noise ratio (eCNR). For qualitative comparison, three image quality criteria (contrast, endocardial edge definition, and artefacts) were rated on a 5-point Likert scale (5: excellent, 1: non-diagnostic). Paired t-Test was used for group comparisons, Bland-Altman analysis for agreement between techniques. Inter-reader agreement was compared using intraclass correlation coefficient. RESULTS: IVSD (BH 7.4 ± 2.1 mm vs FB 7.4 ± 1.9 mm, p =.71), biventricular ejection fraction (left ventricle [LV]: 56.4 ± 10.8% vs 56.1 ± 9.3%, p =.83; right ventricle [RV]: 49.5 ± 8.6% vs 49.7 ± 10.1%, p =.83), and biventricular end diastolic volume (LV: 176.3 ± 63.9 ml vs 173.9 ± 64.9 ml, p =.90; RV: 185.4 ± 63.8 ml vs 189.6 ± 66.6 ml, p =.34) were comparable. Mean measurement time for FB short-axis sequences was 8.1 ± 1.3 compared to 4.4 ± 1.3 min for BH (p <.001). Subjective image quality between sequences was deemed comparable, (4.6 ± 0.6 vs 4.5 ± 0.6, p =.26, for 4-chamber views) with a significant difference regarding short-axis views (4.9 ± 0.3 vs 4.5 ± 0.6, p =.008). aSNR was similar (BH 25.8 ± 11.2 vs FB 22.2 ± 9.5, p =.24), while eCNR was higher for BH (89.1 ± 36.1 vs 68.5 ± 32.1, p =.03). CONCLUSION: FB sequences yielded comparable results to BH regarding image quality, biventricular volumetry, and function, though measurement times were longer. The FB sequence described might be clinically valuable when BHs are insufficiently performed.

Assessment of liver cirrhosis severity with extracellular volume fraction MRI.

We aimed to investigate the diagnostic utility of MRI extracellular volume fraction (ECV) for the assessment of liver cirrhosis severity as defined by Child-Pugh class. In this retrospective study, 90 patients (68 cirrhotic patients and 22 controls), who underwent multiparametric liver MRI, were identified. Hepatic T1 relaxation times and ECV were assessed. Clinical scores of liver disease severity were calculated. One-way analysis of variance (ANOVA) followed by Tukey's multiple comparison test, Spearman's correlation coefficient, and receiver operating characteristic (ROC) analysis were used for statistical analysis. In cirrhotic patients, hepatic native T1 increased depending on Child-Pugh class (620.5 ± 78.9 ms (Child A) vs. 666.6 ± 73.4 ms (Child B) vs. 828.4 ± 91.2 ms (Child C), P < 0.001). ECV was higher in cirrhotic patients compared to the controls (40.1 ± 11.9% vs. 25.9 ± 4.5%, P < 0.001) and increased depending of Child-Pugh class (33.3 ± 6.0% (Child A) vs. 39.6 ± 4.9% (Child B) vs. 52.8 ± 1.2% (Child C), P < 0.001). ECV correlated with Child-Pugh score (r = 0.64, P < 0.001). ECV allowed differentiating between Child-Pugh classes A and B, and B and C with an AUC of 0.785 and 0.944 (P < 0.001, respectively). The diagnostic performance of ECV for differentiating between Child-Pugh classes A and B, and B and C was higher compared to hepatic native T1 (AUC: 0.651 and 0.910) and MELD score (AUC: 0.740 and 0.795) (P < 0.05, respectively). MRI-derived ECV correlated with Child-Pugh score and had a high diagnostic performance for the discrimination of different Child-Pugh classes. ECV might become a valuable non-invasive biomarker for the assessment of liver cirrhosis severity.

Free-breathing high resolution modified Dixon steady-state angiography with compressed sensing for the assessment of the thoracic vasculature in pediatric patients with congenital heart disease.

BACKGROUND: Cardiovascular magnetic resonance angiography (CMRA) is a non-invasive imaging modality of choice in pediatric patients with congenital heart disease (CHD). This study was aimed to evaluate the diagnostic utility of a respiratory- and electrocardiogram-gated steady-state CMRA with modified Dixon (mDixon) fat suppression technique and compressed sensing in comparison to standard first-pass CMRA in pediatric patients with CHD at 3 T. METHODS: In this retrospective single center study, pediatric CHD patients who underwent CMR with first-pass CMRA followed by mDixon steady-state CMRA at 3 T were analyzed. Image quality using a Likert scale from 5 (excellent) to 1 (non-diagnostic) and quality of fat suppression were assessed in consensus by two readers. Blood-to-tissue contrast and quantitative measurements of the thoracic vasculature were assessed separately by two readers. CMRA images were reevaluated by two readers for additional findings, which could be identified only on either one of the CMRA types. Paired Student t test, Wilcoxon test, and intraclass correlation coefficients (ICCs) were used for statistical analysis. RESULTS: 32 patients with CHD (3.3 ± 1.7 years, 13 female) were included. Overall image quality of steady-state mDixon CMRA was higher compared to first-pass CMRA (4.5 ± 0.5 vs. 3.3 ± 0.5; P < 0.001). Blood-to-tissue contrast ratio of steady-state mDixon CMRA was comparable to first-pass CMRA (7.85 ± 4.75 vs. 6.35 ± 2.23; P = 0.133). Fat suppression of steady-state mDixon CMRA was perfect in 30/32 (94%) cases. Vessel diameters were greater in first-pass CMRA compared to steady-state mDixon CMRA with the greatest differences at the level of pulmonary arteries and veins (e.g., right pulmonary artery for reader 1: 10.4 ± 2.4 vs. 9.9 ± 2.3 mm, P < 0.001). Interobserver agreement was higher for steady-state mDixon CMRA for all measurements compared to first-pass CMRA (ICCs > 0.92). In 9/32 (28%) patients, 10 additional findings were identified on mDixon steady-state CMRA (e.g., partial anomalous venous return, abnormalities of coronary arteries, subclavian artery stenosis), which were not depicted using first-pass CMRA. CONCLUSIONS: Steady-state mDixon CMRA offers a robust fat suppression, a high image quality, and diagnostic utility for the assessment of the thoracic vasculature in pediatric CHD patients.

Free-breathing non-contrast flow-independent cardiovascular magnetic resonance angiography using cardiac gated, magnetization-prepared 3D Dixon method: assessment of thoracic vasculature in congenital heart disease.

BACKGROUND: To evaluate a non-contrast respiratory- and electrocardiogram-gated 3D cardiovascular magnetic resonance angiography (CMRA) based on magnetization-prepared Dixon method (relaxation-enhanced angiography without contrast and triggering, REACT) for the assessment of the thoracic vasculature in congenital heart disease (CHD) patients. METHODS: 70 patients with CHD (mean 28 years, range: 10-65 years) were retrospectively identified in this single-center study. REACT-CMRA was applied with respiratory- and cardiac-gating. Image quality (IQ) of REACT-CMRA was compared to standard non-gated multi-phase first-pass-CMRA and respiratory- and electrocardiogram-gated steady-state-CMRA. IQ of different vessels of interest (ascending aorta, left pulmonary artery, left superior pulmonary vein, right coronary ostium, coronary sinus) was independently assessed by two readers on a five-point Likert scale. Measurements of vessel diameters were performed in predefined anatomic landmarks (ascending aorta, left pulmonary artery, left superior pulmonary vein). Both readers assessed artifacts and vascular abnormalities. Friedman test, chi-squared test, and Bland-Altman method were used for statistical analysis. RESULTS: Overall IQ score of REACT-CMRA was higher compared to first-pass-CMRA (3.5 ± 0.4 vs. 2.7 ± 0.4, P < 0.001) and did not differ from steady-state-CMRA (3.5 ± 0.4 vs. 3.5 ± 0.6, P = 0.99). Non-diagnostic IQ of the defined vessels of interest was observed less frequently on REACT-CMRA (1.7 %) compared to steady-state- (4.3 %, P = 0.046) or first-pass-CMRA (20.9 %, P < 0.001). Close agreements in vessel diameter measurements were observed between REACT-CMRA and steady-state-CMRA (e.g. ascending aorta, bias: 0.38 ± 1.0 mm, 95 % limits of agreement (LOA): - 1.62-2.38 mm). REACT-CMRA showed high intra- (bias: 0.04 ± 1.0 mm, 95 % LOA: - 1.9-2.0 mm) and interobserver (bias: 0.20 ± 1.1 mm, 95 % LOA: - 2.0-2.4 mm) agreements regarding vessel diameter measurements. Fat-water separation artifacts were observed in 11/70 (16 %) patients on REACT-CMRA but did not limit diagnostic utility. Six vascular abnormalities were detected on REACT-CMRA that were not seen on standard contrast-enhanced CMRA. CONCLUSIONS: Non-contrast-enhanced cardiac-gated REACT-CMRA offers a high diagnostic quality for assessment of the thoracic vasculature in CHD patients.

Diagnostic value of magnetic resonance parametric mapping for non-invasive assessment of liver fibrosis in patients with primary sclerosing cholangitis.

BACKGROUND: Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease, characterized by bile duct inflammation and destruction, leading to biliary fibrosis and cirrhosis. The purpose of this study was to investigate the utility of T1 and T2 mapping parameters, including extracellular volume fraction (ECV) for non-invasive assessment of fibrosis severity in patients with PSC. METHODS: In this prospective study, patients with PSC diagnosis were consecutively enrolled from January 2019 to July 2020 and underwent liver MRI. Besides morphological sequences, MR elastography (MRE), and T1 and T2 mapping were performed. ECV was calculated from T1 relaxation times. The presence of significant fibrosis (≥ F2) was defined as MRE-derived liver stiffness ≥ 3.66 kPa and used as the reference standard, against which the diagnostic performance of MRI mapping parameters was tested. Student t test, ROC analysis and Pearson correlation were used for statistical analysis. RESULTS: 32 patients with PSC (age range 19-77 years) were analyzed. Both, hepatic native T1 (r = 0.66; P < 0.001) and ECV (r = 0.69; P < 0.001) correlated with MRE-derived liver stiffness. To diagnose significant fibrosis (≥ F2), ECV revealed a sensitivity of 84.2% (95% confidence interval (CI) 62.4-94.5%) and a specificity of 84.6% (CI 57.8-95.7%); hepatic native T1 revealed a sensitivity of 52.6% (CI 31.7-72.7%) and a specificity of 100.0% (CI 77.2-100.0%). Hepatic ECV (area under the curve (AUC) 0.858) and native T1 (AUC 0.711) had an equal or higher diagnostic performance for the assessment of significant fibrosis compared to serologic fibrosis scores (APRI (AUC 0.787), FIB-4 (AUC 0.588), AAR (0.570)). CONCLUSIONS: Hepatic T1 and ECV can diagnose significant fibrosis in patients with PSC. Quantitative mapping has the potential to be a new non-invasive biomarker for liver fibrosis assessment and quantification in PSC patients.

Magnetic resonance parametric mapping of the spleen for non-invasive assessment of portal hypertension.

OBJECTIVES: In patients with advanced liver disease, portal hypertension is an important risk factor, leading to complications such as esophageal variceal bleeding, ascites, and hepatic encephalopathy. This study aimed to determine the diagnostic value of T1 and T2 mapping and extracellular volume fraction (ECV) for the non-invasive assessment of portal hypertension. METHODS: In this prospective study, 50 participants (33 patients with indication for trans-jugular intrahepatic portosystemic shunt (TIPS) and 17 healthy volunteers) underwent MRI. The derivation and validation cohorts included 40 and 10 participants, respectively. T1 and T2 relaxation times and ECV of the liver and the spleen were assessed using quantitative mapping techniques. Direct hepatic venous pressure gradient (HVPG) and portal pressure measurements were performed during TIPS procedure. ROC analysis was performed to compare diagnostic performance. RESULTS: Splenic ECV correlated with portal pressure (r = 0.72; p < 0.001) and direct HVPG (r = 0.50; p = 0.003). No significant correlations were found between native splenic T1 and T2 relaxation times with portal pressure measurements (p > 0.05, respectively). In the derivation cohort, splenic ECV revealed a perfect diagnostic performance with an AUC of 1.000 for the identification of clinically significant portal hypertension (direct HVPG ≥ 10 mmHg) and outperformed other parameters: hepatic T2 (AUC, 0.731), splenic T2 (AUC, 0.736), and splenic native T1 (AUC, 0.806) (p < 0.05, respectively). The diagnostic performance of mapping parameters was comparable in the validation cohort. CONCLUSION: Splenic ECV was associated with portal pressure measurements in patients with advanced liver disease. Future studies should explore the diagnostic value of parametric mapping accross a broader range of pressure values. KEY POINTS: • Non-invasive assessment and monitoring of portal hypertension is an area of unmet interest. • Splenic extracellular volume fraction is strongly associated with portal pressure in patients with end-stage liver disease. • Quantitative splenic and hepatic MRI-derived parameters have a potential to become a new non-invasive diagnostic parameter to assess and monitor portal pressure.

CT fatty muscle fraction as a new parameter for muscle quality assessment predicts outcome in venovenous extracorporeal membrane oxygenation.

Impaired skeletal muscle quality is a major risk factor for adverse outcomes in acute respiratory failure. However, conventional methods for skeletal muscle assessment are inapplicable in the critical care setting. This study aimed to determine the prognostic value of computed tomography (CT) fatty muscle fraction (FMF) as a biomarker of muscle quality in patients undergoing extracorporeal membrane oxygenation (ECMO). To calculate FMF, paraspinal skeletal muscle area was obtained from clinical CT and separated into areas of fatty and lean muscle based on densitometric thresholds. The cohort was binarized according to median FMF. Patients with high FMF displayed significantly increased 1-year mortality (72.7% versus 55.8%, P = 0.036) on Kaplan-Meier analysis. A multivariable logistic regression model was built to test the impact of FMF on outcome. FMF was identified as a significant predictor of 1-year mortality (hazard ratio per percent FMF, 1.017 [95% confidence interval, 1.002-1.033]; P = 0.031), independent of anthropometric characteristics, Charlson Comorbidity Index, Simplified Acute Physiology Score, Respiratory Extracorporeal Membrane Oxygenation Survival Prediction Score, and duration of ECMO support. To conclude, FMF predicted 1-year mortality independently of established clinical prognosticators in ECMO patients and may have the potential to become a new muscle quality imaging biomarker, which is available from clinical CT.

Influence of hydration status on cardiovascular magnetic resonance myocardial T1 and T2 relaxation time assessment: an intraindividual study in healthy subjects.

BACKGROUND: Myocardial native T1 and T2 relaxation time mapping are sensitive to pathological increase of myocardial water content (e.g. myocardial edema). However, the influence of physiological hydration changes as a possible confounder of relaxation time assessment has not been studied. The purpose of this study was to evaluate, whether changes in myocardial water content due to dehydration and hydration might alter myocardial relaxation times in healthy subjects. METHODS: A total of 36 cardiovascular magnetic resonance (CMR) scans were performed in 12 healthy subjects (5 men, 25.8 ± 3.2 years). Subjects underwent three successive CMR scans: (1) baseline scan, (2) dehydration scan after 12 h of fasting (no food or water), (3) hydration scan after hydration. CMR scans were performed for the assessment of myocardial native T1 and T2 relaxation times and cardiac function. For multiple comparisons, repeated measures ANOVA or the Friedman test was used. RESULTS: There was no change in systolic blood pressure or left ventricular ejection fraction between CMR scans (P > 0.05, respectively). T1 relaxation times were significantly reduced with dehydration (987 ± 27 ms [baseline] vs. 968 ± 29 ms [dehydration] vs. 986 ± 28 ms [hydration]; P = 0.006). Similar results were observed for T2 relaxation times (52.9 ± 1.8 ms [baseline] vs. 51.5 ± 2.0 ms [dehydration] vs. 52.2 ± 1.9 ms [hydration]; P = 0.020). CONCLUSIONS: Dehydration may lead to significant alterations in relaxation times and thereby may influence precise, repeatable and comparable assessment of native T1 and T2 relaxation times. Hydration status should be recognized as new potential confounder of native T1 and T2 relaxation time assessment in clinical routine.