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Applications of New Imaging Techniques in Digestive System

Imaging Evaluation of Portosystemic Collateral Vessels of Liver Cirrhosis by MultiDetector Row Spiral CT Portal Venography

ObjectiveTo introduce the technique of threedimensional portal venography of multidetector row spiral CT and its clinical application in the evaluation of the portosystemic collateral shunts of liver cirrhosis. MethodsAll relevant literatures were retrospectively reviewed on the application of twodimensional and threedimensional reconstruction techniques such as MIP, SSD, VRT of multidetector row spiral CT to demonstrate the collateral vessels of liver cirrhosis.ResultsThe distribution, pathway and anatomy of portosystemic collateral vessels were well shown by multidetector row spiral CT portal venography. Conclusion Multidetector row spiral CT portal venography provides excellent depiction of the anatomic characteristics of the collateral shunts and enables the continuous tracing of vascular structures, thus it is very helpful in the imaging evaluation of the collateral vessels of liver cirrhosis.

Nodular Lesions of Cirrhotic Liver: Imaging Manifestations with Pathologic Correlation

ObjectiveTo introduce the new nomenclature scheme of the International Working Group (1995) on hepatic nodules, and summarize the imaging features of various hepatic nodules in light of their pathological characteristics, and evaluate the diagnostic values of various imaging facilities.MethodsUltrasound, computed tomography(CT), magnetic resonance imaging(MRI), and angiographic CT were reviewed and introduced.ResultsMany of these types of hepatic nodules play a role in the de novo and stepwise carcinogenesis of hepatocellular carcinoma(HCC) in the following steps: regenerative nodule, lowgrade dysplastic nodule, highgrade dysplastic nodule, small HCC, and large HCC. Accompanying such transformations, there are significant alterations in the blood supply and perfusion of these hepatic nodules.ConclusionModern stateoftheart medical imaging facilities can not only delineate and depict these hepatic nodules, but also provide important clues for the characterization of focal hepatic lesions in most cases, thus facilitating the early detection, diagnosis and management of HCC in its early stage.

Relationship of Magnetic Resonance DiffusionWeighted Imaging to Histology in Chronic Viral Hepatitis

【Abstract】ObjectiveTo investigate the relationship of magnetic resonance diffusion-weighted imaging (DWI) to histology in the patients of chronic viral hepatitis. MethodsThirty-five patients of chronic viral hepatitis who received liver biopsy and 10 healthy volunteers were included in this study. All of them underwent DWI on a 3.0T MRI device. Apparent diffusion coefficient (ADC) of the liver were measured respectively when b value were set as 100, 400, 600 and 800 s/mm2. Biopsy specimens were scored for fibrosis and necroinflammation according to the Knodell histology activity index (HAI). ResultsWhen b value was set as 800 s/mm2, statistical difference was showed between the fibrosis group and the nonfibrosis group, statistical difference was also shown among the different degrees of necroinflammation and fibrosis. ConclusionDWI is a valuable method for grading and staging of chronic viral hepatitis.

Clinical Applications of Hepatic 31P-MR Spectrocscopy

【Abstract】Objective To summarize the principle and clinical applications of 31phosphorus MR spectroscopy（31pMRS）. Methods Literatures about 31PMRS in liver were reviewed and analyzed. Results Abnormalities of 31PMRS were found in patients of hepatitis, liver cirrhosis, liver tumor，obstructive jaundice and patients after liver transplantation. Evaluation of 31PMRS is important in diagnosis and treatment of many hepatic diseases. Conclusion As a noninvasive protocol for analyzing the energetic metabolism and biomedical changes in cellular level of living liver, 31PMRS has a wide clinical application.

Diagnostic Value of CT and MRI on Acute Cholecystitis

Objective　 To investigate the diagnostic value of CT scanning and MR imaging on acute cholecystitis. Methods　The　CT or MR imaging data of 21 patients with proved acute cholecystitis were retrospectively reviewed. Eleven patients were examined with contrast-enhanced multi-detector-row spiral CT scanning and other 10 cases underwent contrast-enhanced MR imaging. Results　Nineteen patients showed obscure gallbladder outlines （90.5%）. The gallbladder wall demonstrated even thickening in 15 patients （71.4%） and irregular thickening in 6 cases （28.6%）. All patients showed inhomogeneous enhancement of the gallbladder wall （100%）. The bile was hyper-dense or hyper-intense on T1W image in 11 cases （52.4%）. Ten cases had free peri-cholecystic effusion （47.6%）, and 16 cases had peri-cholecystic adhesive changes or fat swelling （76.2%）. Patchy or linear-like transient enhancement of the adjacent hepatic bed in the arterial phase was seen in 16 cases （76.2%）. Twelve patients developed pleural effusion, or ascites, or both （57.1%）. Gallbladder perforation complicated with peritonitis was seen in one case, micro-abscess formation and pneumocholecystitis was observed in another case, and one case had gallbladder diverticulum. Conclusion　Wall blurring, pericholecystic adhesion or fat edema, and transient enhancement of adjacent hepatic bed in the arterial phase are the imaging findings specifically associated with acute cholecystitis, which are readily appreciated on contrast-enhanced multi-phasic CT and MR scanning.

Collateral Venous Pathways in Pancreatogenic Splenic Vein Occlusion： Spiral CT Manifestations

Objective To investigate the spiral CT manifestations of the collateral circulation pathways resulting from splenic vein occlusion (SVO) duo to pancreatic diseases. Methods The CT imaging and clinical data of 33 cases of pancreatic disease with SVO, including 28 cases of pancreatic carcinoma, 3 cases of acute pancreatitis and 2 cases of chronic pancreatitis, were retrospectively analyzed.Results Tortuous and dilated vessels were observed in the areas between splenic hilum and gastric fundus and/or along the gastric greater curvature in all 33 cases. In isolated SVO cases, the short gastric vein (SGV, 86%)，coronary vein (CV, 79%)，gastroepiploic vein (GEV, 79%) and gastrocolic trunk (GCT, 57%) were varicose and dilated. While in nonisolated SVO，other collateral veins such as the right superior colic vein (RSCV, 37%），middle colic vein (MCV, 37%） and posterior superior pancreaticoduodenal vein (PSPDV, 21%） were seen as well. Conclusion The two predominant collateral pathways of SVO are ①SGV→gastric fundal veins→CV， and ②GEV→GCT→SMV. They have characteristic imaging features on spiral CT and are of clinical significance in both preoperative staging of pancreatic carcinoma and the evaluation of pancreatogenic segmental portal hypertension.

Differentiation of Chronic Mass-Forming Type Pancreatitis from Pancreatic Carcinoma by Functional Magnetic Resonance Imaging

Objective　To summarize the principle and application of functional MR imaging of pancreatic carcinoma and chronic mass-forming type pancreatitis. Methods　Articles about diffusion-weighted imaging (DWI), magnetic resonance spectrum imaging (MRSI) and dynamic contrast-enhanced MR imaging of pancreatic carcinoma and chronic pancreatitis were reviewed and analyzed. Results　Functional MR imaging could reflected the differences in molecules diffusion, metabolism and tissue perfusion between pancreatic carcinoma and chronic pancreatitis. Conclusion　 As a non-invasive protocol, functional MR imaging can provide useful information in differential diagnosis between chronic mass-forming type pancreatitis and pancreatic carcinoma.

Spiral CT Manifestations of Blunt Liver Trauma

【Abstract】ObjectiveTo investigate the spectrum of spiral CT imaging findings of blunt liver trauma.MethodsClinical data of 17 patients with blunt liver trauma were retrospectively collected. All patients underwent standardized spiral CT examination of the upper abdomen, which include plain scan, arterial phase and portal venous phase acquisition. The morphology, density and integrity of liver parenchyma and intrahepatic venous structures were carefully observed, as well as regions of porta hepatis, peritoneal cavity and retroperitoneal space.ResultsTwelve cases (70.6%) developed hepatic parenchymal laceration. There were 9 cases (52.9%) of traumatic hematoma, among which 5 were intraparenchymal and 4 were subcapsular. One case (5.9%) showed active bleeding within an intrahepatic hematoma, while two cases (11.8%) had injury (laceration) of hepatic veins. There were 7 patients (41.2%) who demonstrated the so-called “halo sign” around the intrahepatic portal branches. Thirteen patients were associated with peritoneal fluid (blood) collection, 3 with hematoma or hemorrhage of the right adrenal gland, 8 with plural effusion and 3 cases with rib fractures of right lower chest. ConclusionCT imaging findings of blunt liver trauma include parenchymal laceration, intraparenchymal and /or subcapsular hematomas, active hemorrhage, and tear of hepatic veins. Plain CT scan and contrastenhanced dualphase acquisition is very important for the comprehensive evaluation of patients with blunt liver trauma.

Value of MR Diffusion-Weighted Imaging for Differentiating Pancreatic Carcinoma from Chronic Focal Pancreatitis on 3.0 T MR System

Objective　To investigate the value of MR diffusion-weighted imaging (DWI) in differentiating pancreatic carcinoma from chronic focal pancreatitis on 3.0 T MR system. Methods　Thirteen patients with proved pancreatic carcinoma, 7 patients with confirmed chronic focal pancreatitis, and 14 healthy volunteers, were included in this study. MR examination including the routine abdomen scanning protocol and DWI was performed for both patients and volunteers. The SE-EPI sequence and ASSET technique were used for DWI. The b values of 400, 600, 800 and 1 000 s/mm2 were selected to acquire the DWI. The corresponding apparent diffusion coefficient (ADC) values were measured in each designated region of interest and statistically analyzed. Results　①DWI of the healthy volunteers showed intermediate signals of pancreas. ②DWI of pancreatic tumor masses showed homogenous high signal intensity relative to the surrounding pancreatic tissue with clear boundary. Under different b values, the tumor ADC values were (1.63±0.235)×10-3 mm2/s, (1.42±0.126)×10-3mm2 /s, (1.36±0.170)×10-3 mm2 /s and (1.26±0.178)×10-3 mm2 /s respectively, which were significantly lower than those of non-tumor region 〔(2.11±0.444)×10-3 mm2 /s, (1.83±0.230)×10-3 mm2 /s, (1.81±0.426)×10-3 mm2 /s, (1.60±0.230)×10-3 mm2 /s〕 and of the normal pancreas 〔(1.85±0.350)×10-3 mm2 /s, (1.69±0.290)×10-3 mm2 /s, (1.67±0.268)×10-3 mm2 /s, (1.42±0.221)×10-3 mm2 /s〕， P＜0.05. ③DWI of chronic focal pancreatitis showed inhomogeneous slightly hyper-intense signal with blurring borders. Under different b values, the ADC values of the inflammatory masses of chronic pancreatitis were (169±0.150)×10-3 mm2 /s, (1.56±0.119)×10-3 mm2 /s, (1.59±0.172)×10-3 mm2/s and (1.35±0.080)×10-3 mm2 /s respectively, which were higher than those of pancreatic carcinoma. When b value was set to 800 s/mm2 , the difference in ADC values between pancreatic carcinoma and chronic focal pancreatitis was statistically significant (P＜0.05). Conclusion　MR DWI can clearly depict the tumor mass of pancreatic carcinoma. In addition, the measurement of ADC values can provide useful information for the differential diagnosis between pancreatic carcinoma and chronic focal pancreatitis.