Reproducibility study of four-dimensional flow MRI of arterial and portal venous liver hemodynamics: influence of spatio-temporal resolution.

PURPOSE: To evaluate influence of variation in spatio-temporal resolution and scan-rescan reproducibility on three-dimensional (3D) visualization and quantification of arterial and portal venous (PV) liver hemodynamics at four-dimensional (4D) flow MRI. METHODS: Scan-rescan reproducibility of 3D hemodynamic analysis of the liver was evaluated in 10 healthy volunteers using 4D flow MRI at 3T with three different spatio-temporal resolutions (2.4 × 2.0 × 2.4 mm(3), 61.2 ms; 2.5 × 2.0 × 2.4 mm(3), 81.6 ms; 2.6 × 2.5 × 2.6 mm(3), 80 ms) and thus different total scan times. Qualitative flow analysis used 3D streamlines and time-resolved particle traces. Quantitative evaluation was based on maximum and mean velocities, flow volume, and vessel lumen area in the hepatic arterial and PV systems. RESULTS: 4D flow MRI showed good interobserver variability for assessment of arterial and PV liver hemodynamics. 3D flow visualization revealed limitations for the left intrahepatic PV branch. Lower spatio-temporal resolution resulted in underestimation of arterial velocities (mean 15%, P < 0.05). For the PV system, hemodynamic analyses showed significant differences in the velocities for intrahepatic portal vein vessels (P < 0.05). Scan-rescan reproducibility was good except for flow volumes in the arterial system. CONCLUSION: 4D flow MRI for assessment of liver hemodynamics can be performed with low interobserver variability and good reproducibility. Higher spatio-temporal resolution is necessary for complete assessment of the hepatic blood flow required for clinical applications.

Corticosteroid-responsive torticollis as a presenting symptom of multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system that rarely presents with movement disorder symptoms upon primary manifestation. We report the case of a 45-year-old patient with no history of any medical condition who presented to our clinic with left-sided torticollis. Interestingly, MRI scan of the brain revealed multiple periventricular T2 hyperintense lesions. Analysis of cerebrospinal fluid (CSF) showed that cell numbers and protein concentration were normal, while oligoclonal IgG synthesis was suggestive of chronic intrathecal inflammation. Therefore, clinically isolated syndrome (CIS) was diagnosed as a primary manifestation of relapsing-remitting MS. In the MRI scans, one lesion was found to be localized to the right cerebral peduncle, thus providing a potential link between torticollis and the autoimmune disorder. Furthermore, the symptoms were completely resolved with corticosteroid treatment alone. This is to our knowledge the first description of an MS case in which the sole primary manifestation was torticollis that could be completely resolved with corticosteroid treatment. We therefore suggest performing a cerebral MRI scan with particular focus on demyelinating lesions in patients with focal dystonia, since there is an increasing number of reports describing MS as a potential cause of secondary dystonia. Notably, early corticosteroid therapy might resolve symptoms.