Questionable correlation of the apparent diffusion coefficient with the histological grade and microvascular invasion in small hepatocellular carcinoma.

AIM: To evaluate the correlation between the apparent diffusion coefficient (ADC) and various histopathological parameters in small hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: In 143 surgically resected small HCCs, the mean and minimum ADC values, tumour-to-liver ADC ratio, and normalised ADC (ADC of the HCC/ADC of the spleen) were correlated to the tumour grade, microvascular invasion (MVI), cellularity, fatty change, degree of fibrosis, and lymphocytic infiltration using linear regression analysis, the Wilcoxon rank sum test, or Spearman's rank correlation. RESULTS: No significant correlation was found between the ADC parameters and tumour grade. In the univariate analysis, the ADC ratio of the tumour was significantly correlated with MVI as well as the degree of fibrosis and lymphocyte infiltration of the HCC (p=0.017, 0.042, and 0.002, respectively). The ADC of the tumour was significantly correlated with the degree of lymphocyte infiltration of the HCC (p=0.049). In the multivariate analysis, the ADC ratio of the tumour was an independent parameter for MVI and the degree of lymphocyte infiltration of the HCC (p=0.034 and <0.001, respectively), and the ADC of the tumour was an independent parameter for the degree of lymphocyte infiltration of the HCC (p=0.009). There was no significant correlation between the other ADCs and pathological tumour parameters. CONCLUSION: The tumour grade of small HCCs was not correlated with ADC parameters. The tumour-to-liver ADC ratio was a significant independent parameter for the degree of lymphocyte infiltration and MVI of small HCCs.

Integration of different criteria for borderline resectable pancreatic cancer using classification tree analysis: the use of radiological tumour-vascular interface in correlation with surgical and pathological outcomes.

AIM: To integrate various criteria for borderline resectable pancreatic cancer (BRPC) based on radiological parameters using classification tree analysis. MATERIALS AND METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. Two hundred and thirty-five tumour-vein interfaces and 67 tumour-artery interfaces in 245 patients with surgically confirmed pancreatic ductal adenocarcinoma who underwent both preoperative computed tomography (CT) and magnetic resonance imaging (MRI) were assessed by two independent readers. Radiological parameters for evaluation of the tumour-vascular interface were boundary, length of interface, degree of circumferential interface, and contour deformity of affected vessels. Classification tree analysis was performed to determine parameters associated with vascular invasion using pathological and surgical results as the reference standard. RESULTS: In the classification tree analysis for the tumour-vein interface, contour deformity and degree of circumferential interface were the first and second determining factors, respectively, for both surgical and pathological vascular invasion. For the tumour-artery interface, boundary and degree of circumferential interface were the first and second determining factors for surgical invasion, while contour deformity and length of interface were the first and second determining factors for pathological invasion. The BRPC group of modified criteria arbitrarily formed based on the results had similar surgical (74.1-81.6%) and pathological (54.3-63.3%) venous invasion compared to that of the National Comprehensive Cancer Network (NCCN) criteria, and the lowest surgical (33.3%) and pathological (6.7%) arterial invasion compared with those in previously established criteria for BRPC (43.3-55.6% and 22.2-26.1%, respectively). CONCLUSION: Various criteria for BRPCs were integrated using classification tree analysis, and a modified criterion for BRPC, which provides satisfactory results, was established.

Value of unenhanced MRI with diffusion-weighted imaging for detection of primary small (≤20 mm) solid pancreatic tumours and prediction of pancreatic ductal adenocarcinoma.

AIM: To determine the diagnostic performance of unenhanced magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI; NonMRI) for the detection of primary small (≤20 mm) pancreatic solid tumours and prediction of pancreatic ductal adenocarcinoma (PDAC) in comparison with pancreatic computed tomography (CT; PanCT) and pancreatic MRI with magnetic resonance cholangiopancreatography (PanMRI). METHODS AND MATERIALS: The institutional review board approved this retrospective study and waived the requirement for informed consent. A total of 126 patients who underwent PanCT and PanMRI, including 94 small (≤20 mm) pancreatic tumours (51 PDACs, 34 neuroendocrine tumours [NETs], nine solid pseudopapillary tumours [SPTs]), and 32 patients with a normal pancreas, comprised the study population. Two observers assessed three sets of images: PanCT, PanMRI and NonMRI (T1- and T2-weighted images and DWI). Receiver operating characteristic curve analysis and diagnostic accuracy using the area under the receiver operating characteristic curve (Az) were used for statistical analysis. RESULTS: On NonMRI and PanMRI, all of tumours except one NET were detected, but eight tumours (six NETs, one PDAC, one SPT) were not detected on PanCT (p<0.01). For prediction of PDAC, the Az value of the NonMRI (0.884 for observer 1; 0.930 for observer 2) was comparable with PanCT (0.922; 0.924; p>0.05), and inferior to PanMRI (0.930; 0.977; p<0.05), but all of 51 PDACs were considered as probable or definite PDAC on NonMRI by both observers. CONCLUSION: NonMRI showed better performance than PanCT, and competitive performance to PanMRI for the detection of primary small solid pancreatic tumours, and showed reasonable sensitivity for prediction of PDACs compared with PanCT and PanMRI.

Risk factor assessment to predict the likelihood of a diagnosis of metastasis for indeterminate hepatic lesions found at computed tomography in patients with rectal cancer.

AIM: To assess the significant factors on rectal magnetic resonance imaging (MRI) to predict the likelihood of a diagnosis of metastasis for indeterminate hepatic lesions found at computed tomography (CT) in patients with rectal cancer. MATERIALS AND METHODS: A total of 207 patients with rectal cancer who underwent preoperative contrast-enhanced abdominopelvic CT, and rectal and liver MRI were included. Univariate analysis and multivariate logistic regression were used to evaluate the determining factors for the significance of indeterminate hepatic lesions on CT in patients with rectal cancer. RESULTS: Hepatic metastases were diagnosed in 29 (20.9%) of 139 patients who had indeterminate hepatic lesions on preoperative CT obtained for rectal cancer. On univariate analysis, carcinoembryonic antigen level, N stage, mesorectal fascia (MRF) invasion, diameter of superior haemorrhoidal vein, and mesorectal vascular lesion (MVL) grade on rectal MRI (p<0.05) were associated with the possibility of metastasis for indeterminate hepatic lesions on CT. On multivariate analysis, MVL grade and MRF invasion on rectal MRI were independent factors associated with the possibility of metastasis for indeterminate hepatic lesions on CT (p<0.0005 and p=0.0066, respectively). CONCLUSION: MVL grade and MRF invasion on rectal MRI are independent factors for estimating hepatic metastasis among indeterminate hepatic lesions on CT in patients with rectal cancer.

Tumefactive gallbladder sludge: the MRI findings.

AIM: To evaluate the conventional and diffusion-weighted magnetic resonance imaging (MRI) images of tumefactive gallbladder sludge. MATERIALS AND METHODS: The institutional review board approved this retrospective study. Between January 2006 and January 2015, 3478 patients were diagnosed with gallbladder sludge by ultrasonography (US). Of them, 12 patients (eight male, four female; mean age, 63.6 years) with 12 tumefactive gallbladder sludge lesions, who underwent subsequent MRI for further evaluation within 1 month, were included in this study. Data regarding the clinical features, presence of enhancement, and signal intensities of the T2-, T1-, and diffusion-weighted images were collected. RESULTS: All cases of tumefactive sludge were detected incidentally. None of the patients had any predisposing factors for biliary sludge. The tumefactive gallbladder sludge was predominantly seen as a well-defined mass-like lesion. It showed hyperintensity on T1-weighted images (91.7%, 11/12), and variable signal intensities on T2-weighted images. Most of the tumefactive sludge lesions showed no enhancement on the dynamic phases (90%, 9/10). There were no cases with diffusion restriction. Among the patients with follow-up US data (n=7), all the lesions were found to have either disappeared or decreased in size. CONCLUSION: Although tumefactive gallbladder sludge on US can mimic gallbladder cancer, its hyperintensity on a T1-weighted image, and the absence of enhancement and diffusion restriction on MRI images can be helpful for differentiating it from a tumorous condition.

Differentiation of solid-type serous cystic neoplasm from neuroendocrine tumour in the pancreas: value of abdominal MRI with diffusion-weighted imaging in comparison with MDCT.

AIM: To evaluate the value of abdominal MRI with diffusion-weighted (DW) imaging for differentiation of solid-type serous cystic neoplasm (SCN) from neuroendocrine tumour (NET) in the pancreas compared with that of CT. MATERIALS AND METHODS: Ten solid-type SCNs and 15 NETs were included in the study. Qualitative and quantitative analyses were performed, and two observers independently reviewed CT and MRI images for diagnosis of solid-type SCNs. Fisher's exact test and Mann-Whitney U-test, diagnostic performance [receiver operating characteristic (ROC) curve analysis] were evaluated. RESULTS: SCNs showed more frequently hypo-attenuation on unenhanced CT images and marked hyperintensity on T2-weighted images compared with NETs (p < 0.01). The density of the tumour on unenhanced CT images and the apparent diffusion coefficient (ADC) value of the tumour were significantly different between SCNs (mean 18.5 HU; mean 2.45 × 10(-3) mm(2)/s) and NETs (mean 39.2 HU; mean 1.51 × 10(-3) mm(2)/s; p < 0.001). In the differentiation of SCNs from NETs, diagnostic performance of MRI with DW images was significantly higher than that of CT imaging (p < 0.01). CONCLUSION: Abdominal DW-MRI shows a higher diagnostic accuracy than abdominal CT imaging in the differentiation of solid-type SCNs from NETs.

The influence of surgical factors on dislocation of the meniscal bearing after Oxford medial unicompartmental knee replacement: a case-control study.

The aim of this study was to evaluate the risk factors for dislocation of the bearing after a mobile-bearing Oxford medial unicompartmental knee replacement (UKR) and to test the hypothesis that surgical factors, as measured from post-operative radiographs, are associated with its dislocation From a total of 480 UKRs performed between 2001 and 2012, in 391 patients with a mean age of 66.5 years (45 to 82) (316 female, 75 male), we identified 17 UKRs where bearing dislocation occurred. The post-operative radiological measurements of the 17 UKRs and 51 matched controls were analysed using conditional logistic regression analysis. The post-operative radiological measurements included post-operative change in limb alignment, the position of the femoral and tibial components, the resection depth of the proximal tibia, and the femoral component-posterior condyle classification. We concluded that a post-operative decrease in the posterior tibial slope relative to the pre-operative value was the only significant determinant of dislocation of the bearing after medial Oxford UKR (odds ratio 1.881; 95% confidence interval 1.272 to 2.779). A post-operative posterior tibial slope < 8.45° and a difference between the pre-operative and post-operative posterior tibial slope of > 2.19° may increase the risk of dislocation.

Upper abdominal gadoxetic acid-enhanced and diffusion-weighted MRI for the detection of gastric cancer: Comparison with two-dimensional multidetector row CT.

AIM: To evaluate the diagnostic performance of abdominal magnetic resonance imaging (MRI) for the detection of gastric cancer in comparison with that of two-dimensional (2D) multidetector row computed tomography (CT). MATERIALS AND METHODS: The study included 189 patients with 170 surgically confirmed gastric cancers and 19 patients without gastric cancer, all of whom underwent gadoxetic acid-enhanced MRI with diffusion-weighted (DW) imaging, and multidetector contrast-enhanced abdominal CT imaging. Two observers independently analysed three sets of images (CT set, conventional MRI set, and combined conventional and DW MRI set). A five-point scale for likelihood of gastric cancer was used. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were evaluated. Quantitative [apparent diffusion coefficient (ADC) analyses with Mann-Whitney U-test were conducted for gastric cancers and the nearby normal gastric wall. RESULTS: The diagnostic accuracy and sensitivity for detection of gastric cancer were significantly higher on combined conventional and DW MRI set (77.8-78.3%; 75.3-75.9%) than the CT imaging set (67.7-71.4%; 64.1-68.2%) or the conventional MRI set (72-73%; 68.8-70%; p < 0.01). In particular, for gastric cancers with pT2 and pT3, the combined conventional and DW MRI set (91.6-92.6%) yielded significantly higher sensitivity for detection of gastric cancer than did the CT imaging set (76.8-81.1%) by both observers (p < 0.01). The mean ADC of gastric cancer lesions (1 ± 0.23 × 10(-3) mm(2)/s) differed significantly from that of normal gastric wall (1.77 ± 0.25 × 10(-3) mm(2)/s; p < 0.01). CONCLUSION: Abdominal MRI with DW imaging was more sensitive for the detection of gastric cancer than 2D-multidetector row CT or conventional MRI alone.

Inflammatory myofibroblastic tumours of the liver: gadoxetic acid-enhanced and diffusion-weighted MRI findings with 18F-FDG PET/CT and clinical significance of regression on follow-up.

AIM: To assess gadoxetic acid-enhanced and diffusion-weighted (DW) magnetic resonance imaging (MRI) findings of inflammatory myofibroblastic tumours (IMTs) of the liver using combined 2-[(18)F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT), and to evaluate clinical course with volume change on follow-up. MATERIALS AND METHODS: Gadoxetic acid-enhanced and DW MRI findings of 18 histopathologically proven hepatic IMTs in 13 patients were retrospectively reviewed. The clinical features, qualitative (signal intensity and enhancement pattern) and quantitative data [apparent diffusion coefficient (ADC)], and analysis of FDG-PET/CT findings were collected. The volume of IMTs during follow-up was measured using a tumour half-time. RESULTS: Most of the IMTs (9/13, 69.2%) were found incidentally. IMTs were predominantly seen as well-defined (16/18, 88.9%) masses with peritumoural hypointensity during the hepatobiliary phase (17/18, 94.4%) and showed five morphological types: target-like hypervascular mass (n = 9), hypovascular mass (n = 5), heterogeneous enhancing mass (n = 2), sclerosing mass (n = 1), and non-target hypervascular mass (n = 1). All lesions showed diffusion restriction and hypermetabolic mass on FDG-PET/CT images. The mean ADC value and ADC ratio of IMTs to liver were 0.828 × 10(-3) mm(2)/s and 0.76, respectively. On follow-up, all 11 IMTs showed rapid regression (mean tumour half-time, 38.49 days) with no tumour recurrence or distant metastasis. CONCLUSION: Although hepatic IMTs can mimic abscess and malignant tumours at MRI and PET/CT, peritumoural hypointensity during the hepatobiliary phase with rapid regression on follow-up could be helpful for differentiating it from other lesions.

Differentiating xanthogranulomatous cholecystitis from wall-thickening type of gallbladder cancer: added value of diffusion-weighted MRI.

AIM: To evaluate the benefit of diffusion-weighted imaging (DWI) in differentiating xanthogranulomatous cholecystitis from the wall-thickening type of gallbladder cancer. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board. Fourteen patients with xanthogranulomatous cholecystitis and 19 patients with the wall-thickening type of gallbladder cancer were included. Qualitative (visual diffusion restriction compared to liver parenchyma) and quantitative [apparent diffusion coefficient (ADC)] analyses were performed. Conventional MRI findings including dynamic enhancement pattern between the two groups were also analysed. Two observers independently reviewed conventional magnetic resonance imaging (MRI) images and subsequently reviewed combined conventional MRI and DWI images. Pairwise comparison of the receiver operating characteristic (ROC) curves was used to compare diagnostic performances. RESULTS: In conventional MRI findings, xanthogranulomatous cholecystitis showed significant continuity of enhancing mucosal line [79% (11/14) versus 26% (5/19), p = 0.003] and intramural T2-high signal intensity [64% (9/14) versus 21% (4/19), p = 0.012] compared to the wall-thickening type of gallbladder cancer. The enhancement pattern of gallbladder cancer compared to liver parenchyma showed earlier onset than that of xanthogranulomatous cholecystitis (p = 0.001). Diffusion restriction was more frequently seen in the wall-thickening type of gallbladder cancer (68%, 13/19) than in xanthogranulomatous cholecystitis (7%, 1/14; p < 0.001). The mean ADC value of xanthogranulomatous cholecystitis was higher than that of the wall-thickening type of gallbladder cancer with statistical significance (1.637 × 10(-3) mm(2)/s versus 1.076 × 10(-3) mm(2)/s, p = 0.005). Diagnostic performance [area under ROC curve (Az)] of both observers improved significantly after additional review of DWI; Az improved from 0.737 to 0.930 (p = 0.027) for observer 1 and from 0.675 to 0.938 (p = 0.008) for observer 2. CONCLUSION: Addition of DWI to conventional MRI improves discrimination between xanthogranulomatous cholecystitis and the wall-thickening type of gallbladder cancer.

Pathological correlation with diffusion restriction on diffusion-weighted imaging in patients with pathological complete response after neoadjuvant chemoradiation therapy for locally advanced rectal cancer: preliminary results.

OBJECTIVE: The objective of this study was to assess causative pathological factors associated with diffusion restriction on diffusion-weighted imaging (DWI) in patients who achieved pathological complete response (pCR) after treatment with neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer. METHODS: In total, 43 patients with locally advanced rectal cancer (≥T3 or lymph node positive) who underwent neoadjuvant CRT, subsequent surgery and ultimately achieved pCR were enrolled. All patients underwent pre- and post-CRT 3.0 T rectal MRI with DWI. Two radiologists blinded to pathological staging reviewed pre- and post-CRT 3.0 T rectal MRI for the presence of diffusion restriction in the corresponding tumour areas on post-CRT DWI, with a third radiologist arbitrating any disagreement. The consensus of these findings was then correlated with pathological data such as intramural mucin and the degree of proctitis and mural fibrosis seen on surgical specimen. Additionally, the pre-CRT tumour volume was measured to define the effect of this variable on the degree of radiation proctitis and fibrosis, as well as the presence of intramural mucin. RESULTS: Diffusion restriction occurred in 18 subjects (41.9%), while 25 subjects remained diffusion restriction-free (58.1%). The diffusion restriction group tended to have more severe proctitis and mural fibrosis when compared with non-diffusion restriction group (p<0.001). Intramural mucin was also more common in the diffusion restriction group (p=0.052). Higher pre-CRT tumour volumes were significantly predictive of the degree of proctitis (p=0.0247) and fibrosis (p=0.0445), but not the presence of intramural mucin (p=0.0944). Proctitis and mural fibrosis severity were also identified as independent pathological risk factors for diffusion restriction on multivariate analysis (p=0.0073 and 0.0011, respectively). CONCLUSION: Both radiation-induced proctitis and fibrosis were significant and independent predictors of diffusion restriction in patients achieving pCR after treatment with neoadjuvant CRT for locally advanced rectal cancer, and pre-CRT tumour volume significantly affects both variables.

Phase II study with oxaliplatin and S-1 for patients with metastatic colorectal cancer.

BACKGROUND: To evaluate the efficacy and safety of the combination of oxaliplatin and S-1 (OS) in treating metastatic colorectal cancer. PATIENTS AND METHODS: Eligible patients were those with measurable lesions, no previous history of chemotherapy (except adjuvant chemotherapy), an age of 18-70 years, and an Eastern Cooperative Oncology Group performance status of zero to two. Oxaliplatin 130 mg/m(2) was administered i.v. on day 1, and S-1 40 mg/m(2) b.i.d. was administered orally on days 1-14, every 3 weeks. RESULTS: Forty-eight patients (median age, 56 years) were enrolled: 23 had colon cancer, seven rectosigmoid colon cancer; and 18 rectal cancer. Of the 48 patients, 31 were diagnosed with metastatic cancer and 17 had relapsed cancer after surgery, with adjuvant chemotherapy or chemoradiotherapy. In total, 413 cycles were administered (median 6 per patient; range 2-24). Toxicity was evaluated in 48 patient and response in 46. Major toxic effects were grade 3/4 thrombocytopenia (13%) and neutropenia (10%). The overall response rate was 54% [95% confidence interval (CI) 40% to 68%]. The median time to progression and median survival time were 8.5 (95% CI 6.2-10.9) months and 27.2 (95% CI 20.3-34.0) months, respectively. CONCLUSIONS: These data indicate that the OS regimen is effective and well tolerated in patients with advanced colorectal cancer.

Radiologic spectrum of cholangiocarcinoma: emphasis on unusual manifestations and differential diagnoses.

Most cholangiocarcinomas are ductal adenocarcinomas that arise from both intra- and extrahepatic bile duct epithelium, and their typical growth pattern can be classified as exophytic, infiltrative, polypoid, or a combination of these. Those of unusual histologic type (eg, mucin-hypersecreting cholangiocarcinoma, squamous adenocarcinoma, biliary cystadenocarcinoma, and mucinous carcinoma) show a growth pattern different from that of the typical ones (ie, ductal). Cholangiocarcinomas frequently develop in patients with any of a variety of preexisting bile duct diseases, some of which are considered precursors of cholangiocarcinoma (eg, biliary lithiasis, clonorchiasis, recurrent pyogenic cholangitis, and primary sclerosing cholangitis). Some bulky hepatic tumors of either primary or secondary origin mimic exophytic peripheral cholangiocarcinoma. Some variants of hepatocellular carcinoma, such as sclerosing, fibrolamellar, and cholangiohepatocellular carcinoma, resemble exophytic peripheral cholangiocarcinoma, while that with intraductal growth resembles polypoid cholangiocarcinoma. Among benign bile duct diseases, tumorous conditions (eg, benign biliary tumors) may mimic polypoid cholangiocarcinoma, whereas benign stricture of various causes (eg, cholangitides, traumatic and postsurgical sequelae, chronic pancreatitis, papillary stenosis) usually mimics infiltrative cholangiocarcinoma.