A Comparative Study of Survivor Outcomes between Preoperative Evaluation Using CT Alone and Combined CT and MRI in Patients with Pancreatic Ductal Adenocarcinoma.

Purpose: To compare the recurrence pattern, disease-free survival (DFS), and overall survival (OS) after curative surgery for pancreatic ductal adenocarcinoma (PDAC) in patients who underwent preoperative evaluation with CT alone or in combination with MRI, and to compare the prognosis according to the first recurrence site. Materials and Methods: We retrospectively evaluated 152 patients who underwent R0 resection of PDAC. Preoperative CT or combined CT and MRI were performed for 103 and 49 patients, respectively. Two radiologists recorded the location and date of the first recurrence in consensus. The recurrence pattern, DFS, and OS were compared between the two groups. OS was analyzed according to the first recurrence site. Results: In both groups, liver metastasis was the most common recurrence pattern. DFS (p = 0.247) or OS (p = 0.067) showed no significant difference between the two groups. OS according to the first recurrence site was the lowest for liver metastasis, followed by locoregional recurrence (p < 0.001). Conclusion: There were no significant differences in the recurrence pattern, DFS, or OS between patients evaluated with preoperative CT alone or with CT and MRI after curative resection of PDAC. Liver metastasis was the most common tumor recurrence pattern with the lowest OS.

Differentiation of hypervascular primary hepatic tumors showing hepatobiliary hypointensity on gadoxetic acid-enhanced magnetic resonance imaging.

PURPOSE: To determine the imaging features that help differentiate hypervascular primary hepatic tumors showing hepatobiliary hypointensity on gadoxetic acid MRI. METHODS: This study comprised 148 patients with pathologically proven hypervascular hepatic tumors who underwent gadoxetic acid MRI. Tumors included 23 atypical focal nodular hyperplasias (FNHs), 11 hepatocellular adenomas (HCAs), 15 neuroendocrine tumors (NETs), 25 intrahepatic cholangiocarcinomas (ICCs), and 74 hepatocellular carcinomas (HCCs). MRIs were analyzed for morphologic features, signal intensity, and enhancement pattern of the tumors to determine the differential features using multivariate logistic regression analysis. We evaluated the diagnostic performance of the MRI features for differentiating the five tumor types upon review by two observers. RESULTS: Multivariate analysis revealed that reverse target sign on hepatobiliary phase in FNHs (p = 0.009), iso or hyperintensity on ADC map in FNHs and HCAs (p = 0.009, < 0.001, respectively), central hypointensity on arterial phase in NETs (p = 0.001), hepatobiliary target sign in ICCs (p = 0.002), the presence of septum and capsule in HCCs (all p < 0.001) were significant independent features of each tumor group over other tumor groups. Diagnostic accuracy for both observers was 98-98.6% for FNHs, 96.6-98% for HCAs, 97.3-98.6% for NETs, 90.5-94.6% for ICCs, and 85.8-93.2% for HCCs. CONCLUSIONS: Ancillary MRI features established in our study can be helpful in the differentiation of hypervascular and hepatobiliary hypointense primary hepatic tumors on gadoxetic acid MRI.

Diagnosis of recurrent HCC: intraindividual comparison of gadoxetic acid MRI and extracellular contrast-enhanced MRI.

PURPOSE: To compare the efficacy of magnetic resonance imaging (MRI) with hepatobiliary agents (HBA-MRI) and MRI with extracellular contrast agents (ECA-MRI) for detection of recurrent hepatocellular carcinoma (HCC) after multiple treatments. METHODS: The institutional review board approved this retrospective study and waived the requirement for informed patient consent. A total of 135 patients with suspected HCC recurrence after 2-5 treatments (surgery, transarterial chemoembolization, and/or radiofrequency ablation) underwent both HBA-MRI and ECA-MRI within a 1 month interval. HBA-MRI and ECA-MRI were analyzed for HCC detection by two observers using a five-point scale. The diagnostic performances according to MRI modality were compared. RESULTS: A total of 136 liver lesions (121 HCCs and 15 benign lesions; median size, 1.9 cm) were identified. ECA-MRI showed greater sensitivity (90.9% vs. 76.9% for observer 1; 91.7% vs. 78.5% for observer 2) and accuracy (91.2% vs. 78.7% for observer 1; 91.9% vs. 80.2% for observer 2) than HBA-MRI for both observers (P = 0.002, 0.003). Fifteen (12.4%) HCCs were correctly diagnosed with ECA-MRI but not with HBA-MRI by both observers. Interobserver agreement was excellent (0.885) for ECA-MRI and substantial (0.749) for HBA-MRI. CONCLUSIONS: For detection of recurrent HCC, ECA-MRI was superior to HBA-MRI in terms of sensitivity and accuracy. Therefore, ECA-MRI could be the preferred imaging modality over HBA-MRI for assessing HCC recurrence following multiple treatments.

Intrahepatic Mass-forming Cholangiocarcinoma: Arterial Enhancement Patterns at MRI and Prognosis.

Purpose To identify whether arterial enhancement pattern at MRI could predict the prognosis after surgical resection of intrahepatic mass-forming cholangiocarcinoma (IMCC). Materials and Methods Patients who underwent curative hepatic resection and preoperative MRI for IMCC from November 2007 to September 2016 were retrospectively evaluated. MRI enhancement pattern was classified by two radiologists. Recurrence and death data were retrieved until September 31, 2017. Prognostic factor analysis was performed by using preoperative and postoperative clinical-pathologic factors, as well as imaging findings. Results Data in 134 patients (median age, 63.0 years; 87 men and 47 women) were evaluated; median tumor size was 4.5 cm. Arterial phase MRI showed diffuse hypoenhancement in 33 patients, peripheral rim enhancement in 81 patients, and diffuse hyperenhancement in 20 patients. The 5-year risk of death in patients with IMCC with diffuse hyperenhancement was lower than that of patients with diffuse hypoenhancement or peripheral rim enhancement (5-year risk of death: 5.9% vs 87.9% vs 59.2%). Diffuse hypoenhancement (hazard ratio [HR], 41; 95% confidence interval [CI]: 5, 312; P < .01) and peripheral rim enhancement (HR, 11; 95% CI: 2, 85; P = .02) were associated with an increased risk of death compared with diffuse hyperenhancement. Patients with diffuse hyperenhancement of IMCCs had more frequent chronic liver disease (13 of 20; 65%), less frequent vascular invasion (six of 20; 30%), and less frequent tumor necrosis (three of 20; 15%) than other enhancement group (P < .05 for all). Conclusion The MRI arterial enhancement pattern was a prognostic marker in the preoperative evaluation of patients with resectable intrahepatic mass-forming cholangiocarcinoma. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Yoon and Lee .

Intra-individual comparison of gadolinium-enhanced MRI using pseudo-golden-angle radial acquisition with gadoxetic acid-enhanced MRI for diagnosis of HCCs using LI-RADS.

OBJECTIVES: To determine the usefulness of extracellular contrast agent (ECA)-enhanced multiphasic liver magnetic resonance imaging (MRI) using a pseudo-golden-angle radial acquisition scheme by intra-individual comparison with gadoxetic acid-MRI (EOB-MRI) with regard to image quality and the diagnosis of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: This prospective study enrolled 15 patients with 18 HCCs who underwent EOB-MRI using a Cartesian approach and ECA-MRI using the pseudo-golden-angle radial acquisition scheme (free-breathing continuous data acquisition for 64 s following ECA injection, generating six images). Two reviewers evaluated the arterial and portal phases of each MRI for artifacts, organ sharpness, and conspicuity of intrahepatic vessels and the hepatic tumors. A Liver Imaging Reporting and Data System category was also assigned to each lesion. RESULTS: There were no differences in the subjective image quality analysis between the arterial phases of two MRIs (p > 0.05). However, ghosting artifact was seen only in EOB-MRI (N = 3). Six HCCs showed different signal intensities in the arterial phase or portal phase between the two MRIs; five HCCs showed arterial hyperenhancement on ECA-MRI, but not on EOB-MRI. The capsule was observed in 15 HCCs on ECA-MRI and 6 HCCs on EOB-MRI. Five and one HCC were assigned as LR-5 and LR-4 with ECA-MRI and LR-4 and LR-3 with EOB-MRI, respectively. CONCLUSION: Free-breathing ECA-enhanced multiphasic liver MRI using a pseudo-golden-angle radial acquisition was more sensitive in detecting arterial hyperenhancement of HCC than conventional EOB-MRI, and the image quality was acceptable. KEY POINTS: • The pseudo-golden-angle radial acquisition scheme can be applied to perform free-breathing multiphasic dynamic liver MRI. • Adopting the pseudo-golden-angle radial acquisition scheme can improve the detection of arterial enhancement of HCC. • The pseudo-golden-angle radial acquisition scheme enables motion-free liver MRI.

Differentiation between inflammatory myofibroblastic tumor and cholangiocarcinoma manifesting as target appearance on gadoxetic acid-enhanced MRI.

PURPOSE: To determine the differential features of inflammatory myofibroblastic tumor (IMT) and intrahepatic cholangiocarcinoma (ICC) manifesting as target appearance on gadoxetic acid-enhanced MRI. METHODS: Twenty-seven patients with 36 IMTs (1.2-6.0 cm) and 34 patients with 34 ICCs (1.5-6.0 cm) who underwent gadoxetic acid-enhanced MRI were enrolled in this study. Two reviewers evaluated morphology, signal intensity, and enhancement features of tumors on T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and gadoxetic acid-enhanced imaging. RESULTS: As for 32 IMTs with target appearance, IMTs most commonly demonstrated early target appearance characterized by a peripheral hypointense rim on unenhanced T1WI (n = 27, 84.4%), central enhanced area with a hypointense rim on arterial phase (AP) and portal venous phase (PVP) (n = 29, 90.6%), and transitional phase (TP) (n = 28, 87.5%). Meanwhile, most of the ICCs showed homogeneous hypointensity on T1WI (100%), a hyperenhancing rim on AP, late target appearance on TP (n = 32, 94.1%) and HBP (n = 32, 94.1%). Target appearance on DWI appearing as hyperintensity with central hypointense area was seen in 2 IMTs and 32 ICCs. On T2WI, 24 IMTs (n = 24, 75.0%) displayed central iso- and peripheral hyperintensity and 27 ICCs (84.4%) showed layered hyperintensity with either brighter or darker area in center. The remaining six IMTs with no target were observed as cystic appearing nodules (n = 3) or ill-defined hypovascular nodules (n = 2) and fibrotic mass (n = 1). CONCLUSION: IMTs often show early target appearance on unenhanced T1WI, and early dynamic phases of gadoxetic acid-enhanced MRI. Target appearance on later phases, such as TP and HBP, and DWI target appearance were commonly in ICCs, but rare in IMTs.

Usefulness of noncontrast MRI in differentiation between gallbladder carcinoma and benign conditions manifesting as focal mild wall thickening.

BACKGROUND: Magnetic resonance imaging (MRI) is a reliable imaging tool for evaluating gallbladder carcinoma, but it is costly and time-consuming. PURPOSE: To compare noncontrast MRI with multidetector row CT (MDCT) and gadoxetic acid-enhanced whole MRI in distinguishing gallbladder carcinoma from benign disease. MATERIALS AND METHODS: 101 patients (36 with gallbladder carcinoma and 65 with benign disease) with mild focal gallbladder wall thickening were included. Two radiologists reviewed the MDCT and MRI to determine the differential features between malignancy and benignity. Then, the diagnostic performance of MDCT and MRI (T1-, T2- and diffusion-weighted images) with and without gadoxetic acid enhancement in the diagnosis of gallbladder carcinoma was evaluated. RESULTS: The benign group more often showed T2 necklace sign or T2 hyperintensity within the thickened wall (P < 0.0001) and T1 hyperintensity within the wall or gallbladder lumen (P = 0.0002). Meanwhile, malignancy more frequently showed T2 moderate hyperintensity of the thickened wall, papillary appearance, and diffusion restriction (all P < 0.0001). There were significant differences in sensitivity (79.2% vs 98.6% for observer 1; 84.7% vs 100% for observer 2) and specificity (80.7% vs 96.9%; 79.2% vs 95.4%) between the MDCT and noncontrast MRI (P < 0.05). We found similar diagnostic values between the noncontrast MRI and whole MRI (P = 0.479-1.000) for both observers. CONCLUSION: Noncontrast MRI could be a useful alternative to gadoxetic acid-enhanced MRI in the diagnosis of gallbladder carcinoma that presents as mild gallbladder wall thickening on MDCT.

Prospective Intraindividual Comparison of Magnetic Resonance Imaging With Gadoxetic Acid and Extracellular Contrast for Diagnosis of Hepatocellular Carcinomas Using the Liver Imaging Reporting and Data System.

We intraindividually compared the efficacy of magnetic resonance imaging (MRI) with extracellular contrast agents (ECA-MRI) and MRI with hepatobiliary agents (HBA-MRI) for the diagnosis of hepatocellular carcinoma (HCC) using the Liver Imaging Reporting and Data System (LI-RADS). Between November 2016 and November 2017, we enrolled 91 patients with chronic liver disease who underwent both ECA-MRI and HBA-MRI within a 1-month interval for a first detected hepatic nodule on ultrasound. In total, 117 observations (95 HCCs, 19 benign lesions, and 3 other malignancies; median size, 18 mm) were identified with surgical resection. Two observers assessed two MRIs based on LI-RADS v2017, with consensus by a third observer. We then compared the diagnostic performance of LR-5 according to LI-RADS and modified LI-RADS. ECA-MRI had higher sensitivity (77.9% versus 66.3%) and accuracy (82.1% versus 72.6%) than HBA-MRI in the LR-5 category (P < 0.001). When applying either modified washout on the portal venous phase (PVP)/transitional phase (TP) of HBA-MRI or isointensity with a capsule during the PVP/delayed phase of ECA-MRI (illusional washout), 13 HCCs on HBA-MRI and 11 HCCs on ECA-MRI were correctly classified as HCC, while achieving 100% specificity. One cholangiocarcinoma was accurately classified only with HBA-MRI due to its targetoid appearance in the TP and hepatobiliary phase. Conclusion: ECA-MRI showed better sensitivity and accuracy than HBA-MRI for the diagnosis of HCC with LI-RADS. We achieved better diagnostic performance when applying a modified washout on PVP/TP HBA-MRI and an illusional washout on ECA-MRI than we did with conventional criteria.

Guidelines for the Diagnosis and Treatment of Chronic Functional Constipation in Korea, 2015 Revised Edition.

The Korean Society of Neurogastroenterology and Motility first published guidelines for chronic constipation in 2005 and was updated in 2011. Although the guidelines were updated using evidence-based process, they lacked multidisciplinary participation and did not include a diagnostic approach for chronic constipation. This article includes guidelines for diagnosis and treatment of chronic constipation to realistically fit the situation in Korea and to be applicable to clinical practice. The guideline development was based upon the adaptation method because research evidence was limited in Korea, and an organized multidisciplinary group carried out systematical literature review and series of evidence-based evaluations. Six guidelines were selected using the Appraisal of Guidelines for Research & Evaluation (AGREE) II process. A total 37 recommendations were adopted, including 4 concerning the definition and risk factors of chronic constipation, 8 regarding diagnoses, and 25 regarding treatments. The guidelines are intended to help primary physicians and general health professionals in clinical practice in Korea, to provide the principles of medical treatment to medical students, residents, and other healthcare professionals, and to help patients for choosing medical services based on the information. These guidelines will be updated and revised periodically to reflect new diagnostic and therapeutic methods.

Missed pancreatic ductal adenocarcinoma: Assessment of early imaging findings on prediagnostic magnetic resonance imaging.

OBJECTIVE: To investigate the early imaging findings and growth rate of pancreatic ductal adenocarcinoma (PDAC), and to assess whether MR imaging detects early PDAC better than CT. MATERIALS AND METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. Twenty-two patients were included, and two radiologists, by consensus, assessed the presence of focal lesions, interruption of the main pancreatic duct (MPD), MPD dilatation, and pancreatitis, volume doubling time (VDT) of PDAC on prediagnostic MR imaging. Two other observers independently reviewed three image sets (CT images, unenhanced MR images, and unenhanced and contrast-enhanced MR images) for the detection of early PDAC. Paired Wilcoxon signed rank test and receiver operating characteristic (ROC) curve analysis were used for statistical analyses. RESULTS: In 20 (90.9%) patients, prediagnostic MR exams showed abnormality, and all of them showed focal lesions on the first abnormal prediagnostic MR exams. Thirteen lesions (65%) showed no MPD interruption and one lesion (5%) was accompanied by pancreatitis. The mean VDT of PDAC was 151.7 days (range, 18.3-417.8 days). Diagnostic performance of unenhanced MR images (Az, 0.971-0.989) and combined unenhanced and contrast-enhanced MR images (Az, 0.956-0.963) was significantly better than that of CT images (Az, 0.565-0.583; p<0.01) for both observers, CONCLUSION: The most common early imaging finding of PDAC on prediagnostic MR exams was a focal lesion with no MPD interruption with a mean volume doubling time of five months. MR imaging was superior to CT for the detection of early PDAC.

Diagnostic accuracy and prognostic impact of restaging by magnetic resonance imaging after preoperative chemoradiotherapy in patients with rectal cancer.

BACKGROUND: The prognostic role of restaging rectal magnetic resonance imaging (MRI) in patients with preoperative CRT has not been established. The goal of this study was to evaluate the diagnostic accuracy and prognostic role of radiological staging by rectal MRI after preoperative chemoradiation (CRT) in patients with rectal cancer. METHODS: A total of 231 consecutive patients with rectal cancer who underwent preoperative CRT and radical resection from January 2008 to December 2009 were prospectively enrolled. The diagnostic accuracy and prognostic significance of post-CRT radiological staging by MRI was evaluated. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of radiological diagnosis of good responders (ypTNM stage 0-I) were 32%, 90%, 65%, and 69%, respectively. The overall accuracy of MRI restating for good responders was 68%. The 5-year disease-free survival rates of patients with radiological and pathological TNM stage 0, stage I, and stage II-III were 100%, 94%, and 76%, respectively (P=0.037), and 97%, 87%, and 73%, respectively (P=0.007). On multivariate analysis, post-CRT radiological staging by MRI was an independent prognostic factor for disease-free survival. CONCLUSION: Radiological staging by MRI after preoperative CRT may be an independent predictor of survival in patients with rectal cancer.

Is colonoscopy necessary after computed tomography diagnosis of acute diverticulitis?

BACKGROUND/AIMS: A diagnosis of acute diverticulitis is based on computed tomography (CT). Colonoscopy is commonly performed after the acute event to exclude other diagnoses. This study aimed to determine whether colonoscopy is necessary and what additional information is gained from a colonoscopy after acute diverticulitis. METHODS: Acute diverticulitis was diagnosed by clinical criteria and characteristic CT findings. We analyzed the number of patients in whom colorectal cancers were diagnosed and other incidental findings of polyps and other diseases. RESULTS: A total of 177 patients were analyzed retrospectively. The mean age was 43.3±15.3 years (range, 13-82 years) and 97 patients (54.8%) were male. Sixty-one patients had undergone a colonoscopy within 1 year of the acute attack. Advanced adenomatous lesions and colonic malignancy were not detected. Nineteen patients (31.1%) had ≥1 polyp and 11 patients (18.0%) had an adenomatous polyp. No new or different diagnosis was made after colonoscopy. None of the 116 patients who did not undergo colonoscopy within a year after acute diverticulitis had a diagnosis of colorectal cancer registered with the Korea Central Cancer Registry. CONCLUSIONS: Routine colonoscopy yields little benefit in patients with acute diverticulitis diagnosed by typical clinical symptoms and CT. The current practice of a colonoscopy after acute diverticulitis needs to be reevaluated.

Value of diffusion-weighted MRI for differentiating malignant from benign intraductal papillary mucinous neoplasms of the pancreas.

OBJECTIVE: The purpose of this study was to evaluate whether the use of diffusion-weighted MRI (DWI) increases diagnostic accuracy in the differentiation of malignant from benign intraductal papillary mucinous neoplasms (IPMNs) of the pancreas over the accuracy of contrast-enhanced MRI with MRCP. MATERIALS AND METHODS: A total of 61 patients with surgically resected IPMNs (19 malignant, 42 benign) who underwent gadoxetic acid-enhanced MRI, DWI, and MRCP were included. Two blinded observers evaluated two image sets, that is, conventional MRI with MRCP images versus combined conventional MRI with MRCP and DW images, and scored their confidence for malignancy of IPMNs. Qualitative analyses of the IPMNs were also conducted. Diagnostic performance (ROC curve analysis), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated. The Fisher exact test was used to compare groups. RESULTS: The diagnostic performance (area under the ROC curve [Az]) with respect to predicting malignancy of IPMNs improved significantly for both observers after additional review of DW images (p < 0.05). The diagnostic accuracy, sensitivity, specificity, PPV, and NPV of combined conventional and DW images were higher than those of conventional MR images alone. Diffusion restriction was more often present in malignant IPMNs (78.9%) than in benign IPMNs (16.7%) (p < 0.001) with excellent interobserver agreement (ĸ = 0.965). CONCLUSION: Compared with conventional MRI alone, adding DWI to conventional MRI improves diagnostic accuracy with increased specificity for differentiating malignant from benign IPMNs of the pancreas.

Differentiation of malignant from benign focal splenic lesions: added value of diffusion-weighted MRI.

OBJECTIVE: The objective of our study was to evaluate the added value of diffusion-weighted imaging (DWI) for distinguishing between malignant and benign focal splenic lesions. MATERIALS AND METHODS: This study included 53 patients with 11 malignant and 42 benign splenic lesions who underwent gadoxetic acid-enhanced MRI and DWI. Qualitative and quantitative analyses were conducted for splenic lesions. Two blinded observers evaluated the two image sets--that is, the conventional MR images alone versus the combined conventional MR and DW images--and scored their confidence for malignancy of splenic lesions. The Fisher exact test and Mann-Whitney U test were performed, and diagnostic performance values (ROC curve analysis) were evaluated. RESULTS: All malignant lesions showed a progressive hypovascular enhancement pattern, whereas the hypervascular enhancement patterns were shown in only benign lesions (n = 20, 47.6%) (p < 0.05). The mean apparent diffusion coefficient (ADC) of the malignant lesions (0.73 × 10(-3) mm(2)/s) was significantly lower than that of the benign lesions (1.21 × 10(-3) mm(2)/s) (p < 0.001). The addition of DW images to conventional MR images showed a significant improvement for predicting malignant splenic lesions (area under ROC curve [Az] without DW images vs with DW images: 0.774 vs 0.983 for observer 1 and 0.742 vs 0.986 for observer 2) (p < 0.001). In addition, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of combined conventional MR and DW images were higher than those of conventional MR images alone. CONCLUSION: The addition of DWI to conventional MRI improves differentiation of malignant from benign splenic lesions.

The role of diffusion-weighted MR imaging for differentiating benign from malignant bile duct strictures.

OBJECTIVES: To assess the added value of diffusion-weighted imaging (DWI) to conventional magnetic resonance imaging (MRI) for differentiating benign from malignant bile duct strictures. METHODS: Twenty-seven patients with a benign stricture and 42 patients with a malignant stricture who had undergone gadoxetic acid-enhanced MRI with DWI were enrolled. Qualitative (signal intensity, dynamic enhancement pattern) and quantitative (wall thickness and length) analyses were performed. Two observers independently reviewed a set of conventional MRI and a combined set of conventional MRI and DWI, and receiver operating characteristic (ROC) curve analysis was assessed. RESULTS: Benign strictures showed isointensity (18.5-70.4 %) and a similar enhancement pattern (22.2 %) to that of normal bile duct more frequently than malignant strictures (0-40.5 % and 0 %) on conventional MRI (P < 0.05). Malignant strictures (90.5-92.9 %) showed hypervascularity on arterial and portal venous phase images more frequently than benign strictures (37.0-70.4 %) (P < 0.01) On DWI, all malignant strictures showed hyperintensity compared with benign cases (70.4 %) (P < 0.001). Malignant strictures were significantly thicker and longer than benign strictures (P < 0.001). The diagnostic performance of both observers improved significantly after additional review of DWI. CONCLUSIONS: Adding DWI to conventional MRI is more helpful for differentiating benign from malignant bile duct strictures than conventional MRI alone. KEY POINTS: • Accurate diagnosis and exclusion of benign strictures of bile duct are important. • Diffusion-weighted MRI helps to distinguish benign from malignant bile duct strictures. • DWI plus conventional MRI provides superior diagnostic accuracy to conventional MRI alone.

Should preoperative chest CT be recommended to all colon cancer patients?

OBJECTIVE: The aim of this study was to evaluate the efficacy of preoperative chest computed tomography (CT) and the risk factors for lung metastasis in colon cancer patients without liver metastasis who had negative findings on initial chest X-ray (CXR). BACKGROUND: Preoperative staging with chest CT is recommended in colon cancer patients. However, there have been only scant data on the clinical efficacy. METHODS: Three hundred nineteen consecutive colon cancer patients without liver metastasis were retrospectively reviewed and analyzed. The patients had negative findings on preoperative CXR, and they underwent surgery for colon cancer during the period of January 2008 to April 2010. RESULTS: Lung nodule on chest CT was found in 136 patients (42.6%). Twenty of those were definitely diagnosed with lung metastasis (6.3%) by follow-up chest CT or pathologic confirmation. There was no case of delay in surgery due to findings of lung nodule. Comparing the group with lung metastases to that without lung metastases, postoperative pathologic findings reported more advanced T and N status (P = 0.004, P < 0.001, respectively), and lymphatic invasion was more frequent (P = 0.003) in the group with lung metastasis. By multivariate analysis, CT-predicted lymph node metastases and pathologic lymph node metastases were risk factors for lung metastases. CONCLUSIONS: Preoperative staging chest CT is not beneficial to colon cancer patients without liver metastasis and lymph node metastasis suggested on abdominal and pelvic CT who had negative finding on initial CXR.

The value of gadoxetic acid-enhanced and diffusion-weighted MRI for prediction of grading of pancreatic neuroendocrine tumors.

BACKGROUND: Parenchyma-preserving resection for the treatment of benign pancreatic neuroendocrine tumors (NETs) has been tried, and preoperative prediction of benign pancreatic NET is important. Recently, diffusion-weighted imaging (DWI) of abdomen magnetic resonance imaging (MRI) has been used to characterize benign and malignant tumors and DWI might be helpful in prediction of benign pancreatic NETs. PURPOSE: To evaluate the value of gadoxetic acid-enhanced MRI and DWI in predicting benign pancreatic NETs for determination of parenchyma-preserving resection. MATERIAL AND METHODS: Our ethics committee approved this study with a waiver of informed consent given its retrospective design. We searched radiology and pathology databases from November 2010 to July 2012 to identify patients who underwent surgery for pancreatic NETs (<4 cm). Twenty patients in the benign group and 14 patients in the non-benign group were included in this study. Two radiologists analyzed the morphologic features, signal intensity on MR images including DWI (b = 800), and dynamic enhancement pattern of the tumors with consensus. The tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed. RESULTS: The benign pancreatic NETs were more often round (7/20, 35%) or ovoid (13/20, 65%) in shape and less hypovascular on the arterial phase (3/20, 15%) than were the non-benign pancreatic NETs (1/14, 7.1% and 5/14, 35.8%; 7/14, 50% respectively; P < 0.05). Main pancreatic duct dilatation by tumors was demonstrated only in non-benign pancreatic NETs (4/14, 28.4%; P = 0.021). ADC values and ratios were significantly different between benign pancreatic NETs (mean, 1.48 × 10(-3 )mm(2)/sec, 1.11 ± 0.25, each) and non-benign pancreatic NETs (mean, 1.04 × 10(-3 )mm(2)/sec, 0.74 ± 0.13, each) (P < 0.01). Other qualitative and quantitative analyses between benign and non-benign pancreatic NETs were not significantly different (P > 0.05). CONCLUSION: Abdominal MRI with DWI may be useful for differentiating benign pancreatic NETs from non-benign pancreatic NETs, which might be helpful for determination of parenchyma-preserving resection.

Ectopic pancreas in upper gastrointestinal tract: MRI findings with emphasis on differentiation from submucosal tumor.

BACKGROUND: Ectopic pancreas can frequently be mistaken for other submucosal masses. Ectopic pancreas may follow the signal intensity of mother pancreas on various magnetic resonance (MR) sequences, which might be helpful for differentiation between ectopic pancreas and other submucosal tumors in upper gastrointestinal (UGI) tract. PURPOSE: To evaluate the value of MR imaging (MRI) in differentiating ectopic pancreases from submucosal tumors in UGI tract. MATERIAL AND METHODS: Fifteen patients with ectopic pancreas and 26 patients with UGI submucosal tumors were included. All patients underwent abdominal MRI with diffusion-weighted imaging (DWI) and gadoxetic acid-enhanced MRI. Qualitative (location, contour, growth pattern, lesion border, and presence of intralesional cystic portion and duct-like structure) and quantitative (long diameter [LD], short diameter [SD], LD/SD ratio, signal intensities and apparent diffusion coefficients [ADC], and signal intensity - and ADC ratios of UGI submucosal lesions to pancreas) parameters were compared between ectopic pancreases and UGI submucosal tumors using Fisher's exact test, the Mann-Whitney U test, and receiver-operating characteristic (ROC) analysis. RESULTS: Duodenum was the most common location for ectopic pancreas (12/15, 79.9%), and the gastric body for UGI submucosal tumors (15/26, 57.7%) (P = 0.005). Round shape was an imaging feature more common in UGI submucosal tumors (12/26, 46.2%) than in ectopic pancreas (1/15, 6.7%; P = 0.021). On all of the various pulse sequences of MR images, ectopic pancreas showed isointensity comparable to that of pancreas more frequently than did sequences of UGI submucosal tumors (P < 0.01).The means (0.95 ± 0.09, 0.99 ± 0.06, 1.07 ± 0.08) of the signal intensity ratio of ectopic pancreas to pancreas on fat-suppressed unenhanced T1-weighted, arterial, and portal phase images were significantly higher than those (0.60 ± 0.09, 0.62 ± 0.28, 0.86 ± 0.27) of UGI submucosal tumors (P < 0.05). In contrast, the means (1.05 ± 0.12, 0.93 ± 0.18) of the signal intensity ratios of ectopic pancreas on T2-weighted images and DW images (b = 800 s/mm(2)) were significantly lower than those (1.82 ± 0.39, 2.35 ± 0.94) of UGI submucosal tumors (P < 0.001). On ROC analysis, if absolute value of difference between 1.0 and signal intensity ratio of submucosal lesions to the pancreas on T1-weighted images is <0.21, the sensitivity and specificity reach 100.0% for diagnosis ectopic pancreas from submucosal tumors. CONCLUSION: Abdominal MRI with DWI can be a valuable tool for differentiating ectopic pancreases from UGI submucosal tumors.

Differentiating hepatic abscess from malignant mimickers: value of diffusion-weighted imaging with an emphasis on the periphery of the lesion.

PURPOSE: To evaluate the efficacy of diffusion-weighted imaging (DWI) in differentiating hepatic abscess from malignant mimickers with an emphasis on periphery of the lesions. MATERIALS AND METHODS: Thirty-nine patients with hepatic abscess and 74 patients with malignant hepatic tumors were included, who underwent gadoxetic acid-enhanced MRI. For qualitative and quantitative analysis, signal intensities and apparent diffusion coefficient (ADC) values of the periphery were assessed. Two observers reviewed DWI and ADC maps rated using a 5-point scale. Diagnostic performance was evaluated using the receiver operating characteristics (ROC) curve analysis. RESULTS: The periphery of hepatic abscesses was T1-hypointense, arterial hyperintense, and hypointense on hepatobiliary phase less frequently than that of malignant tumors (P < 0.05). No hepatic abscesses showed peripheral washout on 3-min late phase compared with malignant tumors (59.5%) (P < 0.001). Both groups showed hyperintense rims on DWI, but, 37(94.9%) abscesses revealed rims with high ADC values compared with one (1.4%) malignant tumor (P < 0.001). Mean ADC values of abscesses (1.47 × 10(-3) mm(2) /s ± 0.36 [standard deviation]) were significantly higher than those of malignancies (0.68 × 10(-3) mm(2) /s ± 0.20). Diagnostic performance (area under the ROC curve [Az]) of DWI in identifying hepatic abscess was 0.986 and 0.982 for each observer. CONCLUSION: In addition to conventional MRI, DWI is helpful in differentiating hepatic abscess from malignant mimickers.