Magnetic Resonance Diffusion Kurtosis Imaging for Evaluating Stage of Liver Fibrosis in a Rabbit Model.

RATIONALE AND OBJECTIVES: As an extension of the conventional diffusion weighted imaging, diffusion kurtosis imaging (DKI) is based on the non-Gaussian diffusion model that can inherently account for restricted water diffusion within the complex microstructure of most tissues. This study aimed to investigate association of liver DKI derived parameter with stage of liver fibrosis. MATERIALS AND METHODS: Fifty-six healthy New Zealand white rabbits were enrolled into this study, among which 48 rabbits were randomly given carbon tetrachloride to model liver fibrosis, and 8 rabbits treated with normal saline served as control subjects. All rabbits underwent liver DKI followed by biopsy to stage fibrosis (stages F0-F4) on 6th, 8th, 10th, and 12th weekends after initiation of modeling fibrosis. Mean kurtosis (MK), fractional anisotropy (FA), and mean diffusion (MD) were derived from DKI data. Statistical analysis was to evaluate association of DKI derived parameter with stage of fibrosis. RESULTS: FA (r = 0.512) and MK (r = 0.567) increased, and MD (r = -0.574) decreased with increasing stage of fibrosis from F0 to F4 (all p values < 0.05). Significant differences were found in all parameters between F0 and F3 or F4, F1 and F4, F0 and F1-4, and F0-1 and F2-4 (all p values < 0.05). FA and MD could distinguish between F0 from F2, MD, and MK could distinguish F1 from F3, F0-2 from F3-4, and F1-2 from F3-4, and MK and FA could distinguish F2 from F4, and F0-3 from F4 (all p values < 0.05). According to receiver operating characteristic analysis, MK could best predict stage ≥F1, ≥F2, ≥F3, and F4, and discriminate F1-2 from F3-4 with areas under receiver operating characteristic curve of 0.766-0.930. CONCLUSION: DKI derived parameters can help stage fibrosis.

The angle of pancreaticobiliary junction correlates with acute pancreatitis: a magnetic resonance cholangiopancreatography study.

OBJECTIVE: To study the correlation between the angle of the pancreaticobiliary junction (APJ) and the prevalence of acute pancreatitis using magnetic resonance cholangiopancreatography (MRCP). MATERIALS AND METHODS: From February 2014 to October 2014, thirty two subjects with normal pancreas (group A) and 40 patients with acute pancreatitis (group B) who underwent MRCP were enrolled into our study. The type of biliary duct and main pancreatic duct joining the duodenal wall was reviewed and divided into V, B-P and P-B type. The V type is the pancreatic duct and biliary duct joining the duodenal wall without a common channel; the B-P type is the biliary duct draining into the pancreatic duct and forming a common channel; and the P-B type is the pancreatic duct draining into the biliary duct and forming a common channel. APJ was measured on MRCP. The correlation between the APJ and the prevalence of acute pancreatitis was analyzed. RESULTS: The APJ in group A was smaller than in group B (51.45°±13.51° vs. 65.76°±15.61°, P<0.05). According to the type of biliary duct and main pancreatic duct joining the duodenal wall, the prevalence of acute pancreatitis in the V type and in the B-P type was higher than in the P-B type (12/17 vs. 10/29, or 18/26 vs. 10/29, respectively, all P<0.05), whereas there were no significant difference for the prevalence of acute pancreatitis between the V type and B-P type (P>0.05). The APJ were 59.32°±20.04°, 60.22°±11.06°, 57.13°±17.27°, respectively in V type, B-P type and P-B type joining of main pancreatic duct (P>0.05). CONCLUSIONS: A larger APJ is related to a higher prevalence of acute pancreatitis.

Patterns of portosystemic collaterals and diameters of portal venous system in cirrhotic patients with hepatitis B on magnetic resonance imaging: Association with Child-Pugh classifications.

BACKGROUND AND OBJECTIVE: To determine associations of patterns of portosystemic collaterals and diameters of portal venous system in cirrhotic patients with hepatitis B on magnetic resonance (MR) imaging with Child-Pugh classification. MATERIALS AND METHODS: Eighty-eight consecutive patients with cirrhosis resulting from chronic hepatitis B graded by Child-Pugh classifications were recruited and undergone MR portography. Patterns of the collaterals (presented as no collateral, isolated esophageal varices, and esophageal varices combined with other shunts), and diameters of portal venous system including portal vein (PV), left portal vein (LPV), right portal vein (RPV), splenic vein (SV) and superior mesenteric vein (SMV) were assessed statistically to determine associations of patterns of collaterals and diameters of the portal veins with Child-Pugh classification. RESULTS: From no collateral, to isolated esophageal varices, and to the varices combined with other shunts, the Child-Pugh classifications tended to increase (r=0.516, P<0.001). Diameters of PV, LPV, RPV, SV and SMV tended to increase from Child-Pugh A to B but decrease from B to C. Differences in diameter of LPV and SV were significant between Child-Pugh A-B and C (all P<0.05) while no differences in diameters of other portal veins were found (all P>0.05). For discriminating Child-Pugh A-B from C, either a cut-off LPV diameter of 8.98mm or SV diameter of 9.10mm achieved a sensitivity of 67%-70%, specificity of 51%-53%. CONCLUSION: Patterns of portosystemic collaterals and diameters of LPV and SV tend to be associated with Child-Pugh classifications of cirrhosis.

Renal and perirenal space involvement in acute pancreatitis: An MRI study.

OBJECTIVES: To study the prevalence and characteristics of renal and perirenal space involvement and its relation to the severity of acute pancreatitis (AP) using MRI. METHODS: 115 patients with AP who underwent MRI with the clinical kidney function test were retrospectively analyzed in this study. MRI sequences included conventional and diffusion weighted imaging (DWI) sequences. The renal and perirenal space involvement in AP was noted on MRI. The renal apparent diffusion coefficient (ADC) on DWI was measured for each kidney. The severity of AP on MRI was graded using MR severity index (MRSI). The relationships among the renal and perirenal space involvement on MRI, the renal ADC, MRSI and the results of the kidney function test were analyzed. RESULTS: In the 115 patients with AP, the renal and perirenal space abnormalities detected included renal parenchymal abnormalities (0.8%), abnormalities of the renal collecting system (2.6%), renal vascular abnormalities (1.7%), thickened renal fascia (99%), perirenal stranding (62%) and perirenal fluid collection (40%). The prevalence of perirenal space abnormalities was correlated with the severity of AP based on MRSI (P<0.05). The renal ADC values were lower in patients with abnormal kidney function than in those without kidney injury (P<0.05). The prevalence of kidney function abnormalities was 9.4%, 32% and 100% in mild, moderate, and severe AP cases, respectively (P=0.00). CONCLUSION: Perirenal space involvement is much more than renal parenchymal involvement in AP. The prevalence of perirenal space involvement in AP on MRI has a positive correlation with the severity of AP according to MRSI.

MR imaging of acute pancreatitis: correlation of abdominal wall edema with severity scores.

OBJECTIVE: To study MRI findings of abdominal wall edema (AWE) in acute pancreatitis as well as correlations between AWE and the severity of acute pancreatitis according to the MR severity index (MRSI) and the Acute Physiology And Chronic Healthy Evaluation III (APACHE III) scoring system. MATERIALS AND METHODS: A total of 160 patients with AP admitted to our institution between December 2009 and March 2011 were included in this study. MRI was performed within 48 h after admission. MRI findings of acute pancreatitis were noted, including AWE on the MRI. The abdominal wall area was divided into quarters, and each area involved was recorded as 1 point to score the severity of AWE. The severity of acute pancreatitis was studied using both the MRSI and the APACHE III scoring system. Spearman correlation of AWE with the MRSI and the APACHE III scoring system was analyzed. RESULTS: In 160 patients with acute pancreatitis, 53.8% had AWE on MRI. The average AWE score was 1.2±1.4 points. The prevalence of AWE was 30.5%, 64.5% and 100% in mild, moderate and severe AP, respectively, according to MRSI. AWE on MRI was correlated with MRSI scores (r=0.441, p=0.000). According to APACHE III scores, the averages were 2.0±1.1 and 2.6±1.1 points in mild AP and severe AP, respectively (P=0.016). AWE was slightly correlated with the APACHE III scores (r=0.222, p=0.005). CONCLUSION: AWE on MRI in acute pancreatitis is common, which may be a supplementary indicator in determining the severity of AP.

Gallbladder patterns in acute pancreatitis: an MRI study.

RATIONALE AND OBJECTIVES: The aim of this study was to assess the gallbladder patterns on magnetic resonance imaging (MRI) associated with acute pancreatitis (AP). MATERIALS AND METHODS: There were 197 patients with AP, all of whom had undergone abdominal MRI. AP was categorized as either edematous or necrotizing according to its findings on MRI and graded as mild (0-3 points), moderate (4-6 points), or severe (7-10 points) according to the magnetic resonance severity index. The changes to the walls and dimensions of the gallbladder and common bile duct, in addition to the presence of biliary stones and pericholecystic fluid, were noted and compared with the severity of AP on the basis of the magnetic resonance severity index. RESULTS: Of the 197 patients with AP, 81% were classified as edematous and 19% as necrotizing on MRI. There were 35%, 59%, and 6% of patients with mild, moderate, and severe AP according to the magnetic resonance severity index, respectively. Seventy-six percent of patients had at least one gallbladder abnormality on MRI, including a thickened gallbladder wall (42%), pericholecystic fluid (38%), gallbladder stones (35%), an enlarged gallbladder (24%), dilatation of the common bile duct (16%), and subserosal edema (15%). Eighty-nine percent of patients (34 of 38) with necrotizing AP had gallbladder abnormalities, which was significantly higher than the 72% of patients (115 of 159) with edematous AP (P < .05). The prevalence of gallbladder abnormalities was 64% in patients with mild AP, 81% in those with moderate AP, and 91% in those with severe AP (P < .05 among the three groups). CONCLUSIONS: Most patients with AP have gallbladder abnormalities on MRI, including a thickened gallbladder wall and pericholecystic fluid. The prevalence of gallbladder abnormalities has a positive correlation with the severity of AP on MRI.