Ascites relative enhancement during hepatobiliary phase after Gd-BOPTA administration: a new promising tool for characterising abdominal free fluid of unknown origin.

OBJECTIVES: To correlate the degree of ascites enhancement during hepatobiliary phase after gadobenate dimeglumine (Gd-BOPTA) administration with ascites aetiology. METHODS: IRB-approved retrospective study, need for informed consent was waived. We included 74 consecutive ascitic patients who underwent Gd-BOPTA-enhanced liver MRI including hepatobiliary phase (HBP) images between January 2014 and December 2017. Ascites appearance on unenhanced and HBP images was classified as hypo-, iso- or hyperintense in comparison to paraspinal muscles. Ascites signal intensity on unenhanced and HBP images was measured using round ROIs and was normalised to paraspinal muscles (NSI). Normalised relative enhancement (NRE) between native phase and HBP was calculated. The results were related to ascites aetiology using Wilcoxon and Mann-Whitney tests. RESULTS: On native images, ascites appeared hypointense in 95.9% of the cases and isointense in 4.1%, whereas on HBP images, it appeared hyperintense in 59.4% of the cases, isointense in 36.5% and hypointense in 4.1%. Mean ascites NSI was 0.52 on unenhanced images and 1.50 on HBP ones (p < 0.0001). Mean ascites NRE was 201 ± 133%. Ascites of non-malignant aetiology showed mean NRE of 210 ± 134%, whereas malignant ascites showed mean NRE of 92 ± 20% (p = 0.001). ROC analysis showed that a NRE < 112.5% correlates with malignant aetiology with 100% sensitivity and 83.4% specificity (LR = 5.667). NRE did not show any significant correlation with ascites thickness, eGFR and time interval between contrast administration and HBP acquisition (p > 0.05). CONCLUSIONS: Ascites NRE in HBP after Gd-BOPTA administration is significantly lower in patients with ascites secondary to peritoneal carcinomatosis than in patients with non-malignant ascites. KEY POINTS: • Ascites enhancement in the hepatobiliary phase after Gd-BOPTA administration may determine false positive findings when looking for biliary leaks. • Ascites enhancement in the hepatobiliary phase after Gd-BOPTA administration is lower in patients with peritoneal carcinomatosis than in patients with portal hypertension or congestive heart failure. • None of the patients with peritoneal carcinomatosis showed an ascites enhancement of more than 112% as compared with unenhanced images.

A Simplified Callosal Angle Measure Best Differentiates Idiopathic-Normal Pressure Hydrocephalus from Neurodegenerative Dementia.

BACKGROUND: Idiopathic normal-pressure hydrocephalus (iNPH) can resemble or occur in combination with other brain disorders frequently present in the elderly such as Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). OBJECTIVE: To study the accuracy of a simplified callosal angle measure in differentiating iNPH from DLB and AD using conventional brain MRI. METHODS: 76 patients (24 iNPH, 30 DLB, 22 AD) and 40 healthy controls served as discovering cohort. The callosal angle measure was obtained on standard coronal brain MRI images crossing the corpus callosum midpoint. 41 patients (21 iNPH and 20 DLB/AD) were used as independent validation cohort. A set of other conventional MRI markers of iNPH was also evaluated. RESULTS: iNPH showed a significantly decreased mean callosal angle value compared to both disease groups and controls (iNPH = 109±9; DLB = 136.9±8.2; AD = 135.4±11.3; Controls = 138.5±5.2; p <  0.00001). Using a cut off angle of 123, derived by the mean -3SD of the control group, an accuracy of 96% (sensitivity 100% , specificity 95.4% ) was obtained. By ROC analysis, the area under the curve was 0.99 (95% CI: 0.97-1). The measure was consistent (intra-rater: r = 0.94) and reproducible (inter-rater: r = 0.89). In the validation cohort, this cut off angle value discriminated iNPH from DLB/AD with 97.5% accuracy. None of the conventional MRI signs reached the same accuracy. CONCLUSIONS: This simplified callosal angle measure represents an accurate, reproducible, and easy marker of iNPH.