Authors C. BRUSSAARD (1), J. HENDRICKX (1), P. GYKIERE (2), M. VANDEWOUDE (3), J. DE MEY (1) / [1] Universitair Ziekenhuis Brussel, Brussel, Belgium, Radiology, [2] Universitair Ziekenhuis Brussel, Brussel, Belgium, Nuclear Medicine, [3] Regionaal Ziekenhuis Tienen, Tienen, Belgium, Gastroenterology Introduction There is a lack of reliable examinations for evaluation of biliary excretion time and testing sphincter of Oddi (SO) function. Dynamic ultrasound, dynamic T2 MRI sequences, and cholecystoscintigraphy are all performed under forced secretion (FS) and show variable sensitivity. Aim We describe a non-invasive MRI screening method with hepatospecific contrast (HSC) testing the SO in physiologic conditions. Methods Retrospective study: 35 consecutive pts (mean age 58.3 yrs, range 29-82 yrs, 8 men/27 women) underwent a standard MRI examination of the liver-biliary tree with HSC (Gd-EOB-DTPA) for characterizing a hepatic nodule. They had no complaints of SO dysfunction. The 3D T1 dynamic contrast series contained a series without contrast (t(0)) and a late phase at a variable time due to the dedicated protocol in function of the clinical question. Two radiologists judged in consensus whether the liver parenchyma and biliary tree are opacified and whether the contrast reaches the duodenum clearly in the late phase. Since scintigraphy with FS excludes SOD when the time between the start (t0) and the noticed activity in the duodenum (t(late phase)) is observed within 30 min, this was also our cut-off value. Results In all pts, the liver parenchyma and the biliary tree are opacified. Group A (19/35, 54%) shows clearly HSC in the duodenum in the late phase (t(0)-t(late phase) 25 ± 10 min). No excretion in the duodenum is noted in group B (16/35, t(0)-t(late phase) 19 ± 9 min). No significant differences between group A/B are noted for t(0)-t(late phase), age nor sex. In 15 pts, t(0)-t(late phase) is between 20-30 min. 11/15 (73%) pts belong to group A. 9/16 pts in group B and 5/19 pts in group A had a t(late phase) <20 min. Conclusions The liver enhances after IV administration of the HSC in the early vascular phase. However, the liver and the urinary excretory system are equally responsible (50%/50%) for the elimination of Gd-EOB-DTPA. So, the liver parenchyma enhances a second time in a later phase as the liver metabolizes it with subsequent excretion in the biliary tree and passing the SO in the duodenum. The product is metabolized in the same way as the metabolite in scintigraphy. In our population, 73% of the patients who had their final MRI sequence in the time frame between 20-30 min, showed the contrast in the duodenum, indicative for a normal biliary excretion time. This non-invasive MRI test is 100% specific. However, sensitivity is variable as no cut-off time in physiologic conditions is recommended. False negative results in our study are to be expected in group B with t(late phase) < 20 min (9/16 pts). This MRI test looks promising as a non-invasive screening tool for evaluation of disorders of biliary excretion (SO dysfunction, papillary stenosis/fibrosis, …).
