Yoshihiko Fukukura

HASTE MR cholangiopancreatography in the evaluation of intraductal papillary-mucinous tumors of the pancreas

PURPOSE The aim of this study was to determine the usefulness of MR cholangiopancreatography (MRCP) of intraductal papillary-mucinous tumors. METHOD Thirteen patients with intraductal papillary-mucinous tumors were examined by breath-hold MRCP using a half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence with a body phased-array coil. RESULTS Endoscopic retrograde cholangiopancreatography (ERCP) and MRCP completely imaged the entire main pancreatic duct in 12 and in all 13 patients, respectively. ERCP demonstrated the whole opacification of the cystic lesion in only one patient. MRCP depicted the whole of the cystic lesion in all 11 patients who had cystic lesions. ERCP and MRCP source images depicted a communicating duct between the main pancreatic duct and the cystic lesion in 8 and in all 11 patients, respectively. ERCP depicted papillary projections in the main pancreatic ducts in two patients. MRCP source images depicted papillary projections in the main pancreatic ducts or cystic lesions in five patients. CONCLUSION MRCP may be more useful to reveal the main pancreatic duct, cystic lesion, communicating duct between the main pancreatic duct and cystic lesion, and papillary projections than ERCP in patients with intraductal papillary-mucinous tumors of the pancreas.

Pancreatic Adenocarcinoma: Variability of Diffusion-weighted MR Imaging Findings

PURPOSE To compare the apparent diffusion coefficients (ADCs) of pancreatic adenocarcinomas that appear hyperintense with clearly defined borders (clear hyperintense) with those that do not show clear hyperintense borders on diffusion-weighted magnetic resonance (MR) images. MATERIALS AND METHODS Institutional review board approval was obtained and informed consent was waived. Eighty patients with histologically confirmed pancreatic adenocarcinoma (mean tumor size, 32 mm) underwent fat-suppressed single-shot echo-planar 3.0-T diffusion-weighted MR imaging with diffusion gradients (b = 1000 sec/mm(2)). ADC values of the pancreatic adenocarcinomas (n = 80) and proximal (n = 51) and distal (n = 70) pancreas were compared by using the Friedman test, followed by the Wilcoxon signed-rank test, and the difference in serum amylase levels between pancreatic adenocarcinomas with and without clear hyperintensity was evaluated by using the x(2) test. RESULTS In 38 of 80 patients, pancreatic adenocarcinomas showed clear hyperintensity relative to the surrounding pancreas; 26 were hyperintense with unclear distal borders; 12, isointense; and four, hypointense. In all patients, the mean ADC (± standard deviation) of the tumors (1.16 × 10(-3) mm(2)/sec ± 0.22) was significantly lower than those of the proximal pancreas (1.33 × 10(-3) mm(2)/sec ± 0.16, P < .001) and the distal pancreatic parenchyma (1.24 × 10(-3) mm(2)/sec ± 0.23, P = .004). No significant difference in ADC was seen between the pancreatic adenocarcinomas without clear hyperintensity and the distal pancreas. The frequency of serum amylase levels greater than 120 U/L (2.00 μkat/L) was significantly higher than in those with clear hyperintense pancreatic adenocarcinomas (P < .001). CONCLUSION Diffusion-weighted MR imaging was not useful for delineating 47% of pancreatic adenocarcinomas, because of hyperintensity of the pancreatic parenchyma distal to the cancer.

Intraductal Papillary Mucinous Tumors of the Pancreas

Purpose: To compare the effectiveness of thin-section helical CT and MR imaging with gadolinium-enhanced dynamic technique and MR cholangiopancreatography (MRCP) in the examination of patients with intraductal papillary mucinous tumors. Material and Methods: Helical CT, dynamic MR imaging, and MRCP of 25 intraductal papillary mucinous tumors were compared with ERCP and surgical findings. Results: The duodenal papilla was identified by helical CT and dynamic MR imaging in 11 (44%) and 20 (80%) of the 25 patients, respectively (p<0.05). The main pancreatic duct was visualized on helical CT, dynamic MR imaging, and MRCP in all patients (100%): 25 (96.2%), 24 (92.3%), and 26 (100%) cystic lesions were depicted, respectively. A communicating duct between the main pancreatic duct and the cystic lesion was visualized on helical CT, dynamic MR imaging, and MRCP in 14 (53.8%), 11 (42.3%), and 15 (55.7%) lesions, respectively. The papillary projections corresponding to 3 mm or larger papillary neoplasms were depicted on helical CT and MR imaging in 7 patients (25%). Conclusion: MR imaging was equal or slightly superior to thin-section helical CT in the evaluation of intraductal papillary mucinous tumors.

Cholangiolocellular carcinoma of the liver : CT and MR findings

The authors report two cases of surgically proved cholangiolocellular carcinoma of the liver. Marked contrast enhancement was observed at the periphery of the tumor on CTs and MRIs obtained during the hepatic arterial and portal venous phases, with concentric filling on the delayed images. On T1-weighted and T2-weighted MRIs, the tumor was, respectively, hypointense and hyperintense, with a central hypointense area. Therefore, helical CT and MRI features of these cholangiolocellular carcinomas were thought to be similar to those of cholangiocarcinoma.

FDG PET/CT and diffusion-weighted imaging of head and neck squamous cell carcinoma: comparison of prognostic significance between primary tumor standardized uptake value and apparent diffusion coefficient.

Purpose: To compare primary tumor 18F-fluorodeoxyglucose (FDG) maximum standardized uptake value (SUVmax) and diffusion-weighted imaging (DWI) apparent diffusion coefficient (ADC) obtained in the same patients with head and neck squamous cell carcinoma (HNSCC) to clarify the prognostic significance of both indexes. Materials and Methods: The study population comprised 26 patients with HNSCC visible on both pretreatment FDG PET/CT and DWI. Correlation between SUVmax and ADC (b values; 0 and 800 seconds/mm2) was analyzed by the Spearmans rank test. Disease-free survival (DFS) was calculated by the Kaplan-Meier method. Prognostic significance was assessed by the long-rank test and Cox proportional hazards analysis. Results: SUVmax and ADC correlated significantly and negatively (&rgr; = −0.566, P = 0.005). High (>12.1) SUVmax (P < 0.001), low (⩽0.88) ADC (P = 0.009), high (T3–4) T stage (P = 0.030), and high (N2–3) N stage (P = 0.007) were significant in predicting poor 2-year DFS. The accuracy for predicting disease events was 81% (21/26) for SUVmax (>12.1) and 73% (19/26) for ADC(⩽0.88) without significant difference between them (P = 0.52). Disease event hazards ratios for significant unadjusted SUVmax (P = 0.015) and ADC (P = 0.039) remained significant when adjusted for other dichotomized clinical covariates (SUVmax; P = 0.009–0.039, ADC; P = 0.017–0.037) except SUVmax for ADC and ADC for SUVmax and T stage. Conclusion: These results suggest that pretreatment primary tumor SUVmax and ADC correlate significantly and negatively and both may have similar potential to predict DFS or disease events of HNSCC.

Distinguishing Adrenal Adenomas from Nonadenomas: Combined Use of Diagnostic Parameters of Unenhanced and Short 5-minute Dynamic Enhanced CT Protocol

PURPOSE To retrospectively examine the diagnostic values of individual parameters obtained from unenhanced and 35-second and 5-minute contrast material-enhanced (enhanced) computed tomography (CT) in distinguishing adenomas, particularly lipid-poor adenomas, from nonadenomas and to determine the best diagnostic method by using these parameters. MATERIALS AND METHODS This retrospective study had institutional review board approval; the need for informed consent was waived. The study population consisted of 61 patients (20 men and 41 women; mean age, 58 years) with 68 adrenal masses (53 adenomas and 15 nonadenomas). In each patient, unenhanced CT was followed by 35-second and 5-minute enhanced CT. Adenomas were classified as 30 lipid-rich (<or=10 HU) and 23 lipid-poor (>10 HU) adenomas by using unenhanced attenuation. The diagnostic parameters were tumor size, unenhanced attenuation, 35-second and 5-minute enhanced attenuation, wash-in and washout attenuation, percentage enhancement washout ratio (PEW), and relative PEW (RPEW). The sensitivity, specificity, and accuracy for diagnosing adenomas were calculated by using a threshold level of each parameter determined by the least sum of false-positive and false-negative cases and a combination of the threshold levels with 100% specificity. RESULTS The best results were obtained by using a combination of the threshold levels with 100% (15 of 15) specificity (presence of at least one of the following criteria for diagnosing adenomas: unenhanced attenuation of <or=19 HU, 5-minute attenuation of <or=50 HU, PEW of >or=45%, and RPEW of >or=31%). Sensitivity was 94% (50 of 53) or 87% (20 of 23) and accuracy was 96% (65 of 68) or 92% (35 of 38) for diagnosing total adrenal adenomas or lipid-poor adenomas, respectively. CONCLUSION Combining the diagnostic parameters of the CT protocol can yield diagnostic results comparable to those with previously reported longer dynamic enhanced CT protocols.

Lymphoepithelial cysts of the pancreas: demonstration of lipid component using CT and MRI.

We present two cases of surgically proven lymphoepithelial cyst (LEC) of the pancreas that had a lipid component visualized by CT and MRI. Identification of this component in a pancreatic cystic lesion is a key to favor the diagnosis of LEC or splenic epidermoid cyst over other cystic lesions when the lesion is noted in an elderly patient.

Focal fatty infiltration in the posterior aspect of hepatic segment IV: relationship to pancreaticoduodenal venous drainage

OBJECTIVE:We aimed to investigate the relationship between fatty infiltration in the posterior aspect of hepatic segment IV and pancreaticoduodenal venous drainage.METHODS:Pancreaticoduodenal arteriography was performed in 21 patients who had nontumorous portal perfusion defects in the posterior aspect of hepatic segment IV, as demonstrated on CT during arterial portography (CTAP).RESULTS:In 10 patients, pancreaticoduodenal arteriography showed an aberrant nonportal vessel with flow toward the hepatic hilum in the venous phase. Four of the 10 patients with nonportal vessels from the pancreaticoduodenal arterial system had fatty infiltration in segment IV. In three of these four patients, the fatty infiltration was focal and localized to that area. On the other hand, none of the 11 patients without nonportal vessels from the pancreaticoduodenal arterial system had fatty infiltration in the regions corresponding to the nontumorous portal perfusion defects on CTAP. Moreover, three patients with diffuse fatty liver had a focal nonfatty area in segment IV.CONCLUSIONS:Focal fatty infiltration in the posterior aspect of hepatic segment IV seems to be related to pancreaticoduodenal venous drainage.

Pancreatic neuroendocrine tumors: Correlation between the contrast-enhanced computed tomography features and the pathological tumor grade.

OBJECTIVE To determine whether CT features can predict the pathological tumor grades of pancreatic neuroendocrine tumors (PanNETs) according to the recent WHO classification. MATERIALS AND METHODS In all, 28 patients with histologically confirmed PanNETs underwent preoperative contrast CT examinations. Thirteen tumors were classified as G1 and 15 as G2. Two radiologists independently evaluated the CT features (tumor delineation, peripancreatic vascular involvement, upstream pancreatic duct dilatation, N (regional lymph node metastasis) and M (distant metastasis) grades, tumor homogeneity, cystic or necrotic change, and tumor conspicuity). The tumor sizes and Hounsfield unit values of all PanNETs during each phase on CT were measured by one radiologist. We compared the CT features between pathological tumor grades using Fishers exact test for nominal scales and Mann-Whitney U test for ordinal scales or continuous variables. Additionally, we evaluated the performances of the CT findings and their combinations to diagnose G2 tumors. RESULTS G2 tumors showed significantly larger in tumor size than G1 tumors (p=0.029). All 4 tumors with hepatic metastases were G2. Non-hyperattenuation compared with pancreatic parenchyma during portal venous phase (PVP) was significantly associated with G2 (p=0.016). The accuracy for G2 diagnosis of tumor size (≥20mm), M grade (M1), and tumor conspicuity (non-hyperattenuation during PVP) were 71%, 61%, and 71%, respectively, while the accuracy of their combination was 82%. CONCLUSION Contrast-enhanced CT features (tumor size, M grade, and tumor conspicuity during PVP) can predict the pathological tumor grades of PanNETs.

Quantitative evaluation of liver function with T1 relaxation time index on Gd-EOB-DTPA-enhanced MRI: Comparison with signal intensity-based indices

To evaluate whether the reduction rate of T1 relaxation time of the liver (T1 relaxation time index) before and 20 minutes after gadolinium‐ethoxybenzyl‐diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA) injection has the potential to serve as an magnetic resonance imaging (MRI)‐based liver function test in comparison with signal intensity‐based indices.