Hemodynamic measurements with an abdominal 4D flow MRI sequence with spiral sampling and compressed sensing in patients with chronic liver disease. Issue 4 (14th October 2018) - Bane, Octavia
Abstract : Background: The test–retest/interobserver repeatability and diagnostic value of 4D flow MRI in liver disease is underreported. Purpose: To determine the reproducibility/repeatability of flow quantification in abdominal vessels using a spiral 4D flow MRI sequence; to assess the value of 4D flow parameters in diagnosing cirrhosis and degree of portal hypertension. Study Type: Prospective. Subjects: Fifty‐two patients with chronic liver disease. Field Strength/Sequence: 1.5T/spiral 4D flow acquired in one breath‐hold. Assessment: Thirteen abdominal vessels were identified and segmented by two independent observers to measure maximum and time‐averaged through‐plane velocity, net flow, and vessel cross‐section area. Interobserver agreement and test–retest repeatability were evaluated in 15 and 4 cases, respectively. Prediction of the presence and severity of cirrhosis and portal hypertension was assessed using 4D flow parameters. Statistical Tests: Cohen's kappa coefficient, coefficient of variation (CV), Bland–Altman, Mann–Whitney tests, logistic regression. Results: For all vessels combined, measurements showed acceptable agreement between observers, with Cohen's kappa = 0.70 ( P < 0.001), CV < 21%, Bland–Altman bias <5%, but high limits of agreement ([–75%, 75%]). Test–retest repeatability was excellent in large vessels (CV = 1–15%, bias = 1–25%, Bland–Altman limits of agreement [BALA] = [4%, 150%]), and poor in small vessels (CV = 7–130%, bias = 10–200%, BALA = [8%, 190%]). Average velocity in the right hepatic vein and average area of the splenic vein were higher in cirrhosis ( P = 0.027/0.0039). Flow in the middle hepatic vein strongly correlated with Child–Pugh score (ρ = 0.84, P = 0.0238), while flow in the splenic vein (ρ = 0.43, P = 0.032), time‐average (ρ = 0.46, P = 0.02) and peak velocity in the superior mesenteric vein (ρ = 0.45, P = 0.032), and peak velocity in the infrarenal IVC (ρ = 0.39, P = 0.032) positively correlated with an imaging‐based portal hypertension score. Average area of the splenic vein predicted cirrhosis ( P = 0.019; area under the curve AUC [95% confidence interval, CI] = 0.87 [0.71, 1.00]) and clinically significant portal hypertension ( P = 0.042; AUC [95% CI] = 0.78 [0.57–0.99]). Data Conclusion: Spiral 4D flow allows comprehensive assessment of abdominal vessels in one breath‐hold, with substantial interobserver reproducibility, but variable test–retest repeatability. 4D flow may potentially reflect vascular changes due to cirrhosis and portal hypertension. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:994–1005.