Imaging features of solid pseudopapillary tumor of the pancreas on multi-detector row computed tomography

AIM： To retrospectively analyze the imaging features of solid-pseudopapillary tumors （SPTs） of the pancreas on multi-detector row computed tomography （MDCT） and define the imaging findings suggestive of malignant potential. METHODS： A total of 24 consecutive cases with surgically and pathologically confirmed SPTs of the pancreas underwent preoperative abdominal MDCT studies in our hospital. All axial CT images, CT angiographic images, and coronally and sagittally reformed images were obtained. The images were retrospectively reviewed at interactive picture archiving and communication system workstations. RESULTS： Of the 24 cases of SPTs, 11 cases （45.8%） occurred in the pancreatic head and seven （29.1%） in the tail. Eighteen were pathologically diagnosed as benign and six as malignant. MDCT diagnosis of SPTs was well correlated with the surgical and pathological results （Kappa = 0.6, P 〈 0.05）. The size of SPTs ranged from 3 to 15 cm （mean, 5.8 cm）. When the size of the tumor was greater than 6 cm （including 6 cm）, the possibilities of vascular （8 vs 1） and capsular invasion （9 vs 0） increased significantly （P 〈 0.05）.Two pathologically benign cases with vascular invasion and disrupted capsule on MDCT presented with local recurrence and hepatic metastases during follow-up about 1 year after the resection of the primary tumors. CONCLUSION： Vascular and capsular invasion with superimposed spread into the adjacent pancreatic parenchyrna and nearby structures in SPTs of the pancreas can be accurately revealed by MDCT preoperatively. These imaging findings are predictive of the malignant potential associated with the aggressive behavior of the tumor, even in the pathologically benign cases.

Pancreatitis in patients with pancreas divisum:Imaging features at MRI and MRCP

AIM:To determine the magnetic resonance cholangiopancreatography(MRCP)and magnetic resonance imaging(MRI)features of pancreatitis with pancreas divisum(PD)and the differences vs pancreatitis without divisum.METHODS:Institutional review board approval was obtained and the informed consent requirement was waived for this HIPAA-compliant study.During one year period,1439 consecutive patients underwent successful MRCP without injection of secretin and abdominal MRI studies for a variety of clinical indications using a 1.5 T magnetic resonance scanner.Two experienced radiologists retrospectively reviewed all the studies in consensus.Disputes were resolved via consultation with a third experienced radiologist.The assessment included presence and the imaging findings of PD,pancreatitis,and distribution of abnormalities.The pancreatitis with divisum constituted the study group while the pancreatitis without divisum served as the control group.MRCP and MRI findings were correlated with final diagnosis.Fisher exact tests and Pearson × 2 tests were performed.RESULTS:Pancreatitis was demonstrated at MRCP and MRI in 173 cases(38 cases with and 135 cases without divisum)among the 1439 consecutive cases.The recurrent acute pancreatitis accounted for 55.26%(21 of 38)in pancreatitis patients associated with PD,which was higher than 6.67%(9 of 135)in the control group,whereas the chronic pancreatitis was a dominant type in the control group(85.19%,115 of 135)when compared to the study group(42.11%,16 of 38)(χ 2 = 40.494,P < 0.0001).In cases of pancreatitis with PD,the dorsal pancreatitis accounted for a much higher percentage than that in pancreatitis without PD(17 of 38,44.74% vs 30 of 135,22.22%)(χ 2 = 7.257,P < 0.05).CONCLUSION:MRCP and MRI can depict the features of pancreatitis associated with divisum.Recurrent acute pancreatitis and isolated dorsal involvement are more common in patients with divisum.

Imaging features of intraductal papillary mucinous neoplasms of the pancreas in multi-detector row computed tomography

AIM:To retrospectively evaluate the imaging features of pancreatic intraductal papillary mucinous neoplasms (IPMNs) in multi-detector row computed tomography (MDCT).METHODS: A total of 20 patients with pathologically-confirmed intraductal papillary mucinous neoplasms (IPMNs) were included in this study. Axial MDCT images combined with CT angiography (CTA) and multiplanar volume reformations (MPVR) or curved reformations (CR) were preoperatively acquired. Two radiologists (Tan L and Wang DB) reviewed all the images in consensus using an interactive picture archiving and communication system. The disputes in readings were resolved through consultation with a third experienced radiologist (Chen KM). Finally, the findings and diagnoses were compared with the pathologic results.RESULTS: The pathological study revealed 12 malignant IPMNs and eight benign IPMNs. The diameters of the cystic lesions and main pancreatic ducts (MPDs) were significantly larger in malignant IPMNs compared with those of the benign IPMNs (P<0.05). The combined-type IPMNs had a higher rate of malignancy than the other two types of IPMNs (P<0.05). Tumors with mural nodules and thick septa had a significantly higher incidence of malignancy than tumors without these features (P<0.05). Communication of side-branch IPMNs with the MPD was present in nine cases at pathologic examination. Seven of them were identified from CTA and MPVR or CR images. From comparison with the pathological diagnosis, the sensitivity, specificity, and accuracy of MDCT in characterizing the malignancy of IPMN of the pancreas were determined to be 100%, 87.5% and 95%, respectively.CONCLUSION: MDCT with CTA and MPVR or CR techniques can elucidate the imaging features of IPMNs and help predict the malignancy of these tumors.

Synchronous adenocarcinoma and gastrointestinal stromal tumors in the stomach

AIM:To review the clinicopathological characteristics of concurrent gastrointestinal stromal tumors(GISTs) and gastric adenocarcinoma.METHODS:We retrospectively analyzed eight cases of synchronous adenocarcinoma and GIST in the stomach that had been surgically resected with curative intent between March 2003 and December 2008 in Xinhua hospital and Ruijin hospital.The adenocarcinoma was determined to be the primary tumor based on the histological features.The GIST cells were diffusely and strongly positive for CD34 and CD117.RESULTS:The patients were six men and two women aged 47-80 years(average,68.6 years).GIST was preoperatively detected in only one patient.The average sizes of the gastric adenocarcinomas and GISTs were 6.000 ± 2.6186 cm and 1.825 ± 1.4370 cm,respectively.All GISTs were very low-or low-risk lesions that were detected during evaluation,staging,operation or follow-up for gastric adenocarcinoma.CONCLUSION:We hypothesized that the stomach was influenced by the same unknown carcinogen,resulting in a simultaneous proliferation of different cell lines(epithelial and stromal cell).

CT manifestations and features of solid cystic tumors of the pancreas

Objective: To study retrospectively the manifestations and characteristics of solid cystic tumor of the pan- creas(SCTP) on CT. Methods: Nine patients with solid cystic tumor of the pancreas underwent resection with pathological and immunohistochemical confirmation. All the patients were female, aged 27.7 years on average at onset of the disease. CT scan was performed in patients with or without intravenous injection of contrast medium; it was also performed in the arterial phase in 4 pa- tients. Results: Solid and cystic structures were observed in tumors of the pancreas. Solid structure demonstrated low or iso-density on unenhanced CT, poor enhance- ment in the arterial phase and marked enhancement in the portal venous phase on contrast material-en- hanced CT. Cystic structure showed low density on both pre- and pro-contrast views. The CT findings of tumors with predominantly cystic or equal propor- tion of solid and cystic structure: mural nodules for solid structure, 'floating cloud' signs, or solid and cystic crossing distributions. Cystic structure of tumors predominately solid presenting as a beading appearance under capsule. In round, oval and com- pletely encapsulated tumors in the pancreas, the greater vessel enhanced with well-defined margins on pro-contrast images. No dilatation was observed of the common bile and pancreatic ducts. Conclusion: The characteristics of solid cystic tumor of the pancreas revealed by CT could confirm the di- agnosis of the disease in combination with onset age and sex of patients.

Low contrast medium and radiation dose for hepatic computed tomography perfusion of rabbit VX2 tumor

AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P < 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P < 0.001;r = 0.879,P < 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P < 0.001;r = 0.930,P < 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.