Differentiation of subtypes of renal cell carcinoma: dynamic contrast-enhanced magnetic resonance imaging versus diffusion-weighted magnetic resonance imaging.

OBJECTIVE: The objective was to compare the performance of dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) magnetic resonance (MR) imaging in the differentiation of subtypes of renal cell carcinoma (RCC). MATERIALS/METHODS: This study included 45 renal tumors of clear cell (n=36) and non-clear-cell (n=9) RCC. The contrast enhancement ratios (CERs) and the apparent diffusion coefficient (ADC) values on MR imaging were compared between the clear cell and non-clear-cell RCC groups. RESULTS: In the comparison of diagnostic performance between DCE and DW MR imaging, areas under the curves were 0.968 and 0.797 for the CERs of the corticomedullary and the ADC value. CONCLUSION: The CER of the corticomedullary phase was more reliable in distinguishing between clear cell and non-clear-cell RCCs.

Evaluation of renal cortical thickness by non-contrast-enhanced MR imaging with spatially selective IR pulses: comparison between cirrhotic and non-cirrhotic patients.

OBJECTIVE:: To compare renal cortical thicknesses between patients with and without cirrhosis with normal renal function based on serum creatinine using non-contrast-enhanced steady-state, free precession (SSFP) MRI with spatially selective inversion recovery (IR) pulses and to discuss the clinical implications of measuring renal cortical thickness in patients with cirrhosis. METHODS:: 40 patients with and without cirrhosis who had normal renal function based on serum creatinine and underwent non-contrast-enhanced SSFP imaging with spatially selective IR pulses were included. The renal cortical thickness, renal width, renal cortical width ratio, serum creatinine levels and estimated glomerular filtration rates (eGFRs) were compared between cirrhotic and non-cirrhotic groups. RESULTS:: The mean renal cortical thickness was significantly lower in the cirrhotic group (3.6 ± 0.9 mm) than in the non-cirrhotic group (4.9 ± 0.8 mm; p < 0.001). The mean renal cortical width ratio was significantly lower in the cirrhotic group (0.07 ± 0.02) than in the non-cirrhotic group (0.10 ± 0.02; p < 0.001). The mean serum creatinine and mean eGFR did not show significant differences between the two groups. CONCLUSION:: Measurement of renal cortical thickness by means of non-contrast-enhanced SSFP MRI with spatially selective IR pulses may help evaluate renal function accurately in patients with cirrhosis, in whom it may be overestimated by serum creatinine and eGFR. ADVANCES IN KNOWLEDGE:: (1) The renal corticomedullary junction was clearly depicted by non-contrast-enhanced SSFP MRI with spatially selective IR pulses in all patients with and without cirrhosis. (2) The mean renal cortical thickness measured on the optimal SSFP image with spatially selective IR pulses was significantly lower in the cirrhotic group (3.6 ± 1.0 mm) than in the non-cirrhotic group (4.9 ± 0.8 mm) (p < 0.001), although the mean eGFR did not show a significant difference between the two groups.

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse.

PURPOSE: To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. MATERIALS AND METHODS: Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. RESULTS: Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. CONCLUSION: Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. KEY POINTS: • Secretion grade of pancreatic juice at cine-dynamic MRCP after ingestion was evaluated. • Secretion grade was significantly increased within 19 min after liquid meal ingestion. • Secretion grade showed maximum peak of 2.15 at 5 min after ingestion. • Postprandial changes in pancreatic juice flow can be assessed by cine-dynamic MRCP.

Noninvasive investigation of exocrine pancreatic function: Feasibility of cine dynamic MRCP with a spatially selective inversion-recovery pulse.

PURPOSE: To investigate the feasibility of noncontrast-enhanced cine dynamic magnetic resonance cholangiopancreatography (MRCP) with a spatially selective inversion-recovery (IR) pulse for evaluating exocrine pancreatic function in comparison with the N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) test as a pancreatic exocrine function test. MATERIALS AND METHODS: Twenty subjects with or without chronic pancreatitis were included. MRCP with a spatially selective IR pulse was repeated every 15 seconds for 5 minutes to acquire a total of 20 images (cine-dynamic MRCP). The median and mean frequency of the observation (the number of times) and the moving distance (mean secretion grading scores) of pancreatic juice inflow on cine-dynamic MRCP were compared with a BT-PABA test. RESULTS: The urinary PABA excretion rate (%) had significant positive correlations with both the mean secretion grade (r = 0.66, P = 0.002) and frequency of secretory inflow (r = 0.62, P = 0.004) in cine dynamic MRCP. Both the mean frequency of observations of pancreatic secretory inflow (1.4 ± 1.6 times vs. 14.3 ± 4.2 times, P < 0.001) and the mean secretion grade (grade = 0.16 ± 0.24 vs. grade = 1.81 ± 0.81, P < 0.001) was significantly lower in the chronic pancreatitis group than in the normal subject group. CONCLUSION: Cine dynamic MRCP with a spatially selective IR pulse may have potential for estimating the pancreatic exocrine function noninvasively as a substitute for the BT-PABA test.

Tissue gadolinium deposition in hepatorenally impaired rats exposed to Gd-EOB-DTPA: evaluation with inductively coupled plasma mass spectrometry (ICP-MS).

PURPOSE: This study was undertaken to quantify tissue gadolinium (Gd) deposition in hepatorenally impaired rats exposed to gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) by means of inductively coupled plasma mass spectrometry (ICP-MS) and to compare differences in Gd distribution among major organs as possible triggers for nephrogenic systemic fibrosis. MATERIALS AND METHODS: Five hepatorenally impaired rats (5/6-nephrectomized, with carbon-tetrachloride-induced liver fibrosis) were injected with Gd-EOB-DTPA. Histological assessment was conducted and Gd content of the skin, liver, kidneys, lungs, heart, spleen, diaphragm, and femoral muscle was measured by inductively coupled plasma mass spectrometry (ICP-MS) at 7 days after last injection. In addition, five renally impaired rats were injected with Gd-EOB-DTPA and the degree of tissue Gd deposition was compared with that in the hepatorenally impaired rats. RESULTS: ICP-MS analysis revealed significantly higher Gd deposition in the kidneys, spleen, and liver (p = 0.009-0.047) in the hepatorenally impaired group (42.6 ± 20.1, 17.2 ± 6.1, 8.4 ± 3.2 µg/g, respectively) than in the renally impaired group (17.2 ± 7.7, 5.4 ± 2.1, 2.8 ± 0.7 µg/g, respectively); no significant difference was found for other organs. In the hepatorenally impaired group, Gd was predominantly deposited in the kidneys, followed by the spleen, liver, lungs, skin, heart, diaphragm, and femoral muscle. Histopathological investigation revealed hepatic fibrosis in the hepatorenally impaired group. CONCLUSIONS: Compared with renally impaired rats, tissue Gd deposition in hepatorenally impaired rats exposed to Gd-EOB-DTPA was significantly increased in the kidneys, spleen, and liver, probably due to the impairment of the dual excretion pathways of the urinary and biliary systems.

Measurement of renal cortical thickness using noncontrast-enhanced steady-state free precession MRI with spatially selective inversion recovery pulse: Association with renal function.

PURPOSE: To assess whether noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with a spatially selective inversion recovery (IR) pulse can improve the visibility of renal corticomedullary differentiation in patients showing renal dysfunction, and to investigate the correlation between renal cortical thickness and estimated glomerular filtration rate (eGFR). MATERIALS AND METHODS: Sixty-five patients with and without chronic kidney diseases (CKD) were investigated. Based on eGFR, patients were divided into three groups (Group 1, eGFR < 60; Group 2, eGFR = 60-90; and Group 3, eGFR > 90). All patients underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulses and minimal renal cortical thickness was measured. RESULTS: The mean corticomedullary contrast ratio was significantly higher in SSFP images with optimal TI than in in-phase images in all three groups (P = 0.001). Positive correlation was seen between the corticomedullary contrast ratio in SSFP images with optimal TI and eGFR (P = 0.011, r = 0.314). A significantly positive correlation was observed between minimal renal cortical thickness and eGFR (P < 0.01, r = 0.495). CONCLUSION: Noncontrast-enhanced SSFP MRI with a spatially selective IR pulse using optimal TI can improve the visibility of renal corticomedullary differentiation even in patients with renal insufficiency. The decrease in renal cortical thickness measured using this technique correlated significantly with eGFR.

Traumatic hypovolemic shock revisited: the spectrum of contrast-enhanced abdominal computed tomography findings and clinical implications for its management.

Hypovolemic shock is often seen in patients with severe blunt trauma who have suffered from blood circulation inadequate to maintain oxygen delivery to multiple organs. The early recognition and prompt management of hypovolemic shock in patients with multiple injuries are mandatory to improving prognosis and patient conditions. The diagnostic accuracy of computed tomography (CT) as a primary diagnostic tool is well established. The abdominal organs show several common and classic appearances on contrast-enhanced CT in patients with trauma. The hypovolemic shock complex is reported in the previous literature as decreased enhancement of the viscera, increased mucosal enhancement and luminal dilation of the small bowel, mural thickening and fluid-filled loops of the small bowel, the halo sign and flattening of the inferior vena cava, reduced aortic diameter, and peripancreatic edema. However, there have been controversial CT reports with contradictory appearances. Physicians understanding these findings could prompt alternative approaches to the early assessment and management of hypovolemic shock. The aim of this article is to illustrate common and well-known abdominal CT features in patients with traumatic hypovolemic shock, to discuss controversial CT signs in the pancreas and adrenal gland, and to describe CT findings' clinical implications when managing hypovolemic shock.

Prognosis of small hepatocellular nodules detected only at the hepatobiliary phase of Gd-EOB-DTPA-enhanced MR imaging as hypointensity in cirrhosis or chronic hepatitis.

PURPOSE: To evaluate the prognosis of "strict" high-risk nodules (small hepatocellular nodules detected only in the hepatobiliary phase of initial Gd-EOB-DTPA-enhanced MR examination) in patients with cirrhosis or chronic hepatitis. METHODS AND MATERIALS: The study included thirty-three patients with 60 "strict" high-risk nodules showing hypointensity at the hepatobiliary phase that was undetectable at the vascular phase and other conventional sequences of initial Gd-EOB-DTPA-enhanced MR imaging. These nodules were observed on follow-up MR examinations until hypervascularity was detected. The potential predictive factors for hypervascular transformation were compared between two groups (group A showing hypervascular transformation, group B not showing hypervascularization). RESULTS: Ten (16.7 %) of 60 "strict" high-risk nodules showed hypervascular transformation during follow-up periods (group A). The growth rates of the nodules in group A (6.3 ± 4.5 mm/year) were significantly higher than those in group B (3.4 ± 7.2 mm/year) (p = 0.003). Additionally, the median observation period in group A (177.5 ± 189.5 day) was significantly shorter than in group B (419 ± 372.2 day) (p = 0.045). The other predictive factors were not significantly correlated with hypervascularization. CONCLUSIONS: Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods in association with increased growth rates, indicating that nodule growth rate is an important predictive factor for hypervascularization. KEY POINTS: • "Strict" high-risk nodules are defined as hepatocellular nodules detected only in the hepatobiliary-phase. • Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods. • Increased growth rate is an important predictive factor for hypervascular transformation. • Management of patients with "strict" high-risk nodules becomes more appropriate.

Renal corticomedullary differentiation by non-contrast-enhanced MR imaging with a spatially selective IR pulse at various inversion times: comparison with fast asymmetric spin echo (FASE) and steady-state free-precession (SSFP).

We compared visualization of corticomedullary differentiation between fast asymmetric spin echo (FASE) and steady-state free precession (SSFP) combined with spatially selective inversion recovery (IR) pulse and optimal inversion time (TI). Though the corticomedullary contrast ratio was higher in FASE than SSFP images, visualization of corticomedullary differentiation was significantly better in SSFP images than FASE images obtained with spatially selective IR pulses and optimal TI.

Assessment of physiologic bile flow in the extrahepatic bile duct with cine-dynamic MR cholangiopancreatography and a spatially selective inversion-recovery pulse.

PURPOSE: To determine the feasibility of directly and noninvasively visualizing physiologic bile flow in the extrahepatic bile duct by means of nonpharmacologic cine-dynamic magnetic resonance (MR) cholangiopancreatography with a spatially selective inversion-recovery (IR) pulse and assess the flow dynamic pattern of bile in the extrahepatic bile duct. MATERIALS AND METHODS: The institutional review board approved this retrospective study and waived the need for informed consent. Thirty-five patients without known pancreatobiliary diseases and 11 patients with dilatation of the extrahepatic bile duct were included. Cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse was performed by imaging every 15 seconds over a 5-minute interval (20 images acquired total). The images were evaluated for the visualization of bile flow, the frequency that bile flow was observed in the extrahepatic bile duct, and the distance the bile moved within the area of the IR pulse. Statistical analysis was performed by using Spearman rank correlation coefficient and Mann-Whitney U tests. RESULTS: Antegrade bile flow was observed in 29 of 35 patients (83%) in the nondilated group. Bile flow was observed much more frequently in the nondilated group than in the dilated group (4.4 times vs 1.8 times, P = .029). The distance that bile moved forward within the area of the IR pulse was significantly greater in the nondilated group than in the dilated group (mean grade, 0.44 vs 0.14; P = .033), suggesting stagnation or slowdown of antegrade bile flow in patients with biliary dilatation. Reversed bile flow was also observed in 26 of 35 patients (74%) in the nondilated group without biliary diseases. CONCLUSION: Nonpharmacologic cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse allows direct and noninvasive visualization of bile flow in the extrahepatic bile duct, demonstrating that reversed bile flow is a physiologic phenomenon.

Age-related change in renal corticomedullary differentiation: evaluation with noncontrast-enhanced steady-state free precession (SSFP) MRI with spatially selective inversion pulse using variable inversion time.

PURPOSE: To evaluate age-related change in renal corticomedullary differentiation and renal cortical thickness by means of noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with spatially selective inversion recovery (IR) pulse. MATERIALS AND METHODS: The Institutional Review Board of our hospital approved this retrospective study and patient informed consent was waived. This study included 48 patients without renal diseases who underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulse using variable inversion times (TIs) (700-1500 msec). The signal intensity of renal cortex and medulla were measured to calculate renal corticomedullary contrast ratio. Additionally, renal cortical thickness was measured. RESULTS: The renal corticomedullary junction was clearly depicted in all patients. The mean cortical thickness was 3.9 ± 0.83 mm. The mean corticomedullary contrast ratio was 4.7 ± 1.4. There was a negative correlation between optimal TI for the best visualization of renal corticomedullary differentiation and age (r = -0.378; P = 0.001). However, there was no significant correlation between renal corticomedullary contrast ratio and age (r = 0.187; P = 0.20). Similarly, no significant correlation was observed between renal cortical thickness and age (r = 0.054; P = 0.712). CONCLUSION: In the normal kidney, noncontrast-enhanced SSFP MRI with spatially selective IR pulse can be used to assess renal corticomedullary differentiation and cortical thickness without the influence of aging, although optimal TI values for the best visualization of renal corticomedullary junction were shortened with aging.

Accumulation of Bile in the Gallbladder: Evaluation by means of Serial Dynamic Contrast-Enhanced Magnetic Resonance Cholangiography with Gadolinium Ethoxybenzyl Diethylenetriaminepentaacetic Acid.

The aim of this study was to evaluate the process of biliary excretion of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) into the biliary tract and to assess the accumulation patterns in the gallbladder using MR cholangiography obtained with Gd-EOB-DTPA which is a liver-specific hepatobiliary contrast agent. Seventy-five patients underwent Gd-EOB-DTPA enhanced MR imaging. Serial multiphasic hepatobiliary phase imaging was qualitatively reviewed to evaluate the process of the biliary excretion of contrast agent into the bile duct and the gallbladder. The accumulation pattern of contrast agent into gallbladder was classified into two groups (group 1 = orthodromic type and group 2 = delayed type). Furthermore, the results in differences of the presence of T1 hyperintense bile or sludge of gallbladder, gall stones, wall thickening of gallbladder, chronic liver disease, and liver cirrhosis between two groups were compared. Forty-eight of 75 patients (64%) were included in group 1, and remaining 27 (36%) were in group 2. The frequency of the presence of T1 hyperintense bile or sludge of gallbladder was significantly higher in patients with group 2 than that in patients with group 1 (P = 0.041). MR cholangiography obtained with Gd-EOB-DTPA showed that there may be an association between the biliary accumulation pattern in the gallbladder and the pathological condition.

High-risk nodules detected in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MR imaging in cirrhosis or chronic hepatitis: incidence and predictive factors for hypervascular transformation, preliminary results.

PURPOSE: To evaluate the incidence and predictive factors of hypervascular transformation during follow-up of "high-risk nodules" detected in the hepatobiliary phase of initial Gd-EOB-DTPA-enhanced MRI in chronic liver disease patients. MATERIALS AND METHODS: A total of 109 patients with chronic liver disease who underwent Gd-EOB-DTPA-enhanced MRI several times were investigated. Of these, 43 patients had 76 high-risk nodules with both hypointensity in the hepatobiliary phase and hypovascularity in the arterial phase of initial MRI. These nodules were observed until hypervascularity was detected. MRI and clinical findings were compared to assess the incidence and potential predictive factors for hypervascular transformation between the group showing hypervascular transformation and the group not showing hypervascularization. RESULTS: The median observation period was 242.5 ± 203.2 days (range, 47-802 days). Overall, 24 of 76 high-risk nodules (31.6%) showed hypervascular transformation during follow-up (median observation period, 186.0 ± 190.3 days). The growth rate of the nodules (P < 0.001), the presence of fat within nodules (P = 0.037), and hyperintensity on T1-weighted images (P = 0.018) were significantly correlated with hypervascularization. CONCLUSION: Subsets of high-risk nodules tended to show hypervascular transformation during follow-up, with an increased growth rate, the presence of fat, and hyperintensity on T1-weighted images as predictive factors.

Corticomedullary differentiation of the kidney: evaluation with noncontrast-enhanced steady-state free precession (SSFP) MRI with time-spatial labeling inversion pulse (time-SLIP).

PURPOSE: To assess whether noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with time-spatial labeling inversion pulse (Time-SLIP) can improve the visibility of corticomedullary differentiation of the normal kidney. MATERIALS AND METHODS: A series of noncontrast-enhanced SSFP MRI with Time-SLIP were performed in 20 patients by using various inversion times (TIs); 500-1800 msec in increments of 100 msec. In-phase (IP) and opposed-phase (OP) MR images were also obtained. The signal intensity (SI) of the renal cortex and medulla was measured to calculate corticomedullary contrast ratio (SI of cortex/medulla). Additionally, the visibility of corticomedullary differentiation was visually categorized using a four-point scale. RESULTS: In SSFP with Time-SLIP, corticomedullary contrast ratio was highest with TI of 1200 msec in eight subjects (40%), followed by 1100 msec in seven (35%) and 1000 msec in three (15%). The corticomedullary contrast ratio in SSFP with optimal Time-SLIP (4.93 ± 1.25) was significantly higher (P < 0.001) than those of IP (1.46 ± 0.12) and OP (1.43 ± 0.14). The visibility of corticomedullary differentiation was significantly better (P < 0.001) in SSFP images with Time-SLIP (averaged grade = 4.0) than in IP images (averaged grade = 2.63) and OP images (averaged grade = 2.05). CONCLUSION: SSFP MRI with Time-SLIP can improve the visibility of renal corticomedullary differentiation without using contrast agents.

Hepatic parenchymal enhancement at Gd-EOB-DTPA-enhanced MR imaging: correlation with morphological grading of severity in cirrhosis and chronic hepatitis.

The aim was to clarify whether enhancement effects of the liver parenchyma in the hepatobiliary phase (HP) of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR imaging were correlated with the morphological grading of the severity in cirrhosis. A total of 62 patients with chronic hepatitis or cirrhosis underwent Gd-EOB-DTPA-enhanced MR imaging. Relative enhancement (RE) of liver parenchyma was calculated from signal intensity (SI) measurements obtained at precontrast images (SIpre) and 20-min postcontrast HP images (SIpost) as: (SIpost-SIpre)/SIpre. Morphological MR grades of severity in cirrhosis were divided into four groups. Then, RE of liver parenchyma and morphologic MR grading were correlated. Regarding the morphologic severity of cirrhosis, the numbers of patients with MR grade 1, 2, 3 and 4 were 14 (23%), 7 (11%), 28 (45%) and 13 (21%), respectively. The mean REs of liver parenchyma in each group of MR morphologic grade 1, 2, 3 and 4 were 0.71±0.21, 0.62±0.16, 0.70±0.22 and 0.77±0.18, respectively. There was no significant correlation between the MR grading of morphologic severity and the RE of liver parenchyma at 20-min HP. Hepatic parenchymal enhancement in the HP of Gd-EOB-DTPA-enhanced MR imaging did not necessarily decrease according to the severity of morphologic changes in cirrhosis. This fact may suggest that the hepatic uptake of Gd-EOB-DTPA depends on the preserved hepatocytes function rather than the severity of morphologic changes in cirrhosis.

Age-related changes in normal adult pancreas: MR imaging evaluation.

OBJECTIVE: To investigate age-related changes in normal adult pancreas as identified by magnetic resonance imaging (MRI). MATERIALS AND METHODS: We examined 115 patients without pancreatic diseases (21-90 years) who underwent upper abdominal MRI to evaluate the normal pancreatic MRI findings related to aging. The parameters examined were the pancreatic anteroposterior (AP) diameter, pancreatic lobulation, pancreatic signal intensity (SI), depiction of the main pancreatic duct (MPD), grade of the visual SI decrease on the opposed-phase T1-weighted images compared with in-phase images, and enhancement effect of the pancreas in the arterial phase of dynamic imaging. RESULTS: The pancreatic AP diameter significantly reduced (head, p=0.0172; body, p=0.0007; tail, p<0.0001), and lobulation (p<0.0001) and parenchymal fatty change (p<0.0001) became more evident with aging. No significant correlation was observed between aging and pancreatic SI, however the SI on the in-phase T1-weighted images tended to decrease with aging. No significant correlation was observed between aging and the depiction of the MPD as well as aging and contrast enhancement. CONCLUSION: MRI findings of pancreatic atrophy, lobulation, and fatty degeneration are characteristic changes related to aging, and it is necessary to recognize these changes in the interpretation of abdominal MRI in patients with and without pancreatic disease.