Akihisa Ueno

Virtual Monochromatic Spectral Imaging with Fast Kilovoltage Switching: Improved Image Quality as Compared with That Obtained with Conventional 120-kVp CT

PURPOSE To compare image quality obtained in phantoms with virtual monochromatic spectral (VMS) imaging with that obtained with conventional 120-kVp computed tomography (CT) for a given radiation dose. MATERIALS AND METHODS Three syringes were filled with a diluted contrast medium (each syringe contained a contrast medium with a different iodine concentration [5, 10, or 15 mg of iodine per milliliter]), and a fourth syringe was filled with water. These syringes were placed in a torso phantom meant to simulate the standard human physique. The phantom was examined with a CT system and use of the fast kilovoltage switching (80 and 140 kVp) and conventional (120 kVp) modes. Image noise and contrast-to-noise (CNR) ratio were analyzed on VMS images and 120-kVp CT images. RESULTS Image noise on VMS images in the range of 67-72 keV was significantly lower than that on the 120-kVp CT images (P < .014). Image noise was lowest at 69 keV and was 12% lower when compared with that on 120-kVp CT images. CNR on the VMS images was highest at 68 keV. CNR on the VMS images obtained at 68 keV in the syringes filled with diluted contrast material (5, 10, and 15 mg of iodine per milliliter) was 28%, 31%, and 30% higher, respectively, compared with that on the 120-kVp CT images (P < .001). CONCLUSION VMS imaging at approximately 70 keV yielded lower image noise and higher CNR than did 120-kVp CT for a given radiation dose. VMS imaging has the potential to replace 120-kVp CT as the standard CT imaging modality, since optimal VMS imaging may be expected to yield improved image quality in a patient with standard body habitus.

OATP1B3 expression is strongly associated with Wnt/β-catenin signalling and represents the transporter of gadoxetic acid in hepatocellular carcinoma

BACKGROUND & AIMS In the current era of emerging molecular targeted drugs, it is necessary to identify before treatment the specific subclass to which a tumour belongs. Gadoxetic acid is a liver-specific contrast agent that is preferentially taken up by hepatocytes. Therefore, gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) should provide precise molecular information about hepatocellular carcinomas (HCCs). The aim of this study was to investigate the transporters of gadoxetic acid in HCC comprehensively and to analyse the molecular regulatory mechanism of such transporters. METHODS Expression levels of transporters, transcriptional factors and Wnt target genes in clinical samples were examined by quantitative real-time reverse transcription polymerase chain reaction and immunohistochemistry. LiCl treatment of the HCC cell line KYN-2 was conducted in vitro to assess the effects of Wnt signalling activity. RESULTS Comprehensive analyses of transporter mRNAs and protein expressions revealed that the organic anion transporting polypeptide 1B3 (OATP1B3) had the strongest correlation with tumour enhancement in hepatobiliary-phase images of EOB-MRI. Association analysis with OATP1B3 expression revealed significant correlation with the expression of Wnt/β-catenin target genes. Further, LiCl treatment induced OATP1B3 mRNA expression in KYN-2 cells, indicating a strong association between OATP1B3 expression and Wnt/β-catenin signalling. The sensitivity and specificity to predict Wnt/β-catenin-activated HCC using tumour enhancement in EOB-MRI were 78.9% and 81.7%, respectively. CONCLUSIONS OATP1B3 was confirmed as the most important transporter mediating HCC enhancement in EOB-MRI. OATP1B3 expression showed a strong association with the expression of Wnt/β-catenin target genes, therefore, OATP1B3-upregulated HCC likely represents a specific subclass of Wnt/β-catenin-activated HCC.

Detection of a coronary artery vessel wall: performance of 0.3 mm fine-cell detector computed tomography--a phantom study.

The purpose of this study was to evaluate whether experimental fine-cell detector computed tomography with a 0.3125 mm cell (0.3 mm cell CT) can improve the detection of coronary vessel walls compared with conventional 64-slice computed tomography with a 0.625 mm cell (0.6 mm cell CT). A coronary vessel wall phantom was scanned using 0.6 mm cell CT and 0.3 mm cell CT. The data for 0.3 mm cell CT were obtained using four protocols: a radiation dose equal, double, triple or quadruple that were used in the 0.6 mm cell CT protocol. The detectable size of the vessel wall was assessed based on the first and second derivative functions, and the minimum measurable values were compared using a paired t-test. As a result, the minimum detectable wall thickness of 0.6 mm cell CT (1.5 mm) was significantly larger than that of 0.3 mm cell CT performed using the triple- and quadruple-dose protocols (0.9 mm) and the double-dose protocol (1.1 mm). The difference in the minimum detectable vessel wall thickness measured using 0.6 mm cell CT (1.5 ± 0.1 mm) and 0.3 mm cell CT (0.9 ± 0.1 mm, 1.1 ± 0.2 mm) was significant (p < 0.01). We concluded that 0.3 mm cell CT improved the detection of coronary vessel walls when a more than double-dose protocol was used compared with 0.6 mm cell CT.

Concomitant pancreatic endocrine neoplasm and intraductal papillary mucinous neoplasm: a case report and literature review

We report a case of concomitant pancreatic endocrine neoplasm (PEN) and intraductal papillary mucinous neoplasm (IPMN). A 74-year-old man had been followed-up for mixed-type IPMN for 10 years. Recent magnetic resonance images revealed an increase in size of the branch duct IPMN in the pancreas head, while the dilation of the main pancreatic duct showed minimal change. Although contrast-enhanced computed tomography and magnetic resonance imaging did not reveal any nodules in the branch duct IPMN, endoscopic ultrasound indicated a suspected nodule in the IPMN. A malignancy in the branch duct IPMN was suspected and we performed pylorus-preserving pancreatoduodenectomy with lymphadenectomy. The resected specimen contained a cystic lesion, 10 x 10 mm in diameter, in the head of the pancreas. Histological examination revealed that the dilated main pancreatic duct and the branch ducts were composed of intraductal papillary mucinous adenoma with mild atypia. No evidence of carcinoma was detected in the specimen. Incidentally, a 3-mm nodule consisting of small neuroendocrine cells was found in the main pancreatic duct. The cells demonstrated positive staining for chromogranin A, synaptophysin, and glucagon but negative staining for insulin and somatostatin. Therefore, the 3-mm nodule was diagnosed as a PEN. Since the mitotic count per 10 high-power fields was less than 2 and the Ki-67 index was less than 2%, the PEN was pathologically classified as low-grade (G1) according to the 2010 World Health Organization (WHO) criteria. Herein, we review the case and relevant studies in the literature and discuss issues related to the synchronous occurrence of the relatively rare tumors, PEN and IPMN.

Lymphoepithelioma-like hepatocellular carcinoma: a case report and a review of the literature.

We report a rare case of lymphoepithelioma-like hepatocellular carcinoma. A 79-year-old Japanese man had undergone curative resection of extrahepatic bile ducts because of bile duct cancer 9 years prior. The bile duct cancer was diagnosed as mucosal adenocarcinoma, and the patient had been followed up every 6 months for the last 9 years. A recent computed tomography examination revealed a tumor, 4.2 cm in size, in the lateral segment of the liver. Based on the imaging findings, the tumor was diagnosed as hepatocellular carcinoma. Serology tests were negative for hepatitis B and C viruses. Chest and abdominal image analyses showed no evidence of metastasis, but a swollen lymph node was noted around the abdominal aorta. The patient subsequently underwent extended lateral segmentectomy and resection of the swollen lymph node. Microscopically, the tumor had the characteristic appearance of poorly differentiated hepatocellular carcinoma. Moreover, an abundant infiltration of inflammatory cells was observed in the tumor. Therefore, we diagnosed the tumor as lymphoepithelioma-like hepatocellular carcinoma. The resected para-aortic lymph node also had a carcinoma with features similar to those of the main tumor. The patient has been alive for 20 months since performance of the surgery. Since the first report of lymphoepithelioma-like hepatocellular carcinoma in 2000, only nine cases have been reported in the medical literature, and the clinicopathological features of the disease have not been well documented. Herein, we describe the clinicopathological features of this case for further understanding of the disease and review past cases in the literature.

Preoperative and intraoperative assessment of myometrial invasion in endometrial cancer: comparison of magnetic resonance imaging and frozen sections.

To compare the diagnostic characteristics of the evaluation of myometrial invasion (MI) retrospectively between preoperative magnetic resonance imaging (MRI) and intraoperative frozen sections.

Cystic tumor of the liver without ovarian-like stroma or bile duct communication: two case reports and a review of the literature

We report two cases of cystic neoplasm of the liver with mucinous epithelium in which both ovarian-like stroma and bile duct communication were absent. The first case was a 41-year-old woman. She underwent right trisegmentectomy due to a multilocular cystic lesion, 15 cm in diameter, with papillary nodular components in the medial segment and right lobe. Histologically, arborizing papillae were seen in the papillary lesion. The constituent neoplastic cells had sufficient cytoarchitectural atypia to be classified as high-grade dysplasia. The second case was a 60-year-old woman. She underwent left lobectomy due to a unilocular cystic lesion, 17 cm in diameter, in the left lobe. Histologically, the cyst wall was lined by low columnar epithelia with slight cellular atypia. In both cases, neither ovarian-like stroma nor bile duct communications were found throughout the resected specimen. According to the most recent World Health Organization (WHO) classification in 2010, cystic tumors of the liver with mucinous epithelium are classified as mucinous cystic neoplasms when ovarian-like stromata are found, and as intraductal papillary neoplasm of bile duct when bile duct communication exists. Therefore, we diagnosed the cystic tumors as ‘biliary cystadenoma’ according to the past WHO classification scheme from 2000. We believe that the combined absence of both ovarian-like stroma and bile duct communication is possible in mucinous cystic tumors of the liver. Herein, we have described the clinicopathologic features of the two cases and reviewed past cases in the literature.

Intrahepatic Cholangiocarcinoma Arising 33 Years After Excision of a Choledochal Cyst: Report of a Case

We report a case of intrahepatic cholangiocarcinoma arising 33 years after excision of a choledochal cyst. A 61-year-old woman was admitted to our hospital complaining of fever. Thirty-three years ago she had undergone extrahepatic choledochal cystectomy and choledochojejunostomy for a choledochal cyst. Computed tomography showed a tumor in the anterior segment of the liver, extending to the posterior and medial segments and the right portal vein. Intrahepatic biliary stones were seen in the bile ducts. We performed extended right lobectomy. Microscopically, the tumor was cholangiocarcinoma. Most of the tumor area was composed of invasive adenocarcinoma but a carcinoma-in-situ component was also observed in some regions including the hilar bile duct, where an intrahepatic biliary stone was seen. This suggests that the cancer development could be related to intrahepatic cholestasis. Patients with choledochal cyst may have to be carefully followed up for more than 30 years even after diversion surgery.

Two Cases of Pathological Complete Response to Neoadjuvant Chemoradiation Therapy in Pancreatic Cancer.

Neoadjuvant chemoradiation therapy (NACRT) is increasingly used in patients with a potentially or borderline resectable pancreatic ductal adenocarcinoma (PDA) and it has been shown to improve survival and reduce locoregional metastatic disease. It is rare for patients with PDA to have a pathological complete response (pCR) to NACRT, but such patients reportedly have a good prognosis. We report the clinicopathological findings of two cases of pCR to NACRT in PDA. Both patients underwent pancreatectomy after NACRT (5-fluorouracil, mitomycin C, cisplatin, and radiation). Neither had residual invasive carcinoma and both showed extensive fibrotic regions with several ducts regarded as having pancreatic intraepithelial neoplasia 3/carcinoma in situ in their post-therapy specimens. It is noteworthy that both patients had a history of a second primary cancer. They both had comparatively good outcomes: one lived for 9 years after the initial pancreatectomy and the other is still alive without recurrence after 2 years.

Primary hepatic cancers with multiple pathologic features in a patient with hepatitis C: report of a case.

We report a case of multiple primary hepatic cancers exhibiting different pathologic features coexisting in a patient with chronic hepatitis C. Computed tomography showed 2 tumors in segment 8, 20 mm (S8-A) and 5 mm (S8-B) in diameter, and a 10-mm tumor in segment 6 (S6). Based on the images, the S8-A lesion was diagnosed as cholangiocellular carcinoma or combined hepatocellular carcinoma and cholangiocarcinoma (combined HCC-CC). The other 2 tumors were diagnosed as HCC. The patient underwent partial resections of segments 6 and 8. We found 2 more tumors (S8-C was 6 mm in diameter and S8-D was 4 mm) in the resected segment 8 specimen. Histopathologic examination revealed that the S8-A and S8-C tumors were combined HCC-CC, the S8-B and S6 lesions were scirrhous HCC, and the S8-D tumor was an early HCC. This is a very rare case in which different hepatic cancers with multiple pathologic features coexisted.