Potential conditions causing impairment of selective hepatobiliary enhancement of gadobenate dimeglumine-enhanced delayed magnetic resonance imaging.

OBJECTIVE: To identify conditions that might impair the delayed selective hepatobiliary enhancement of gadobenate dimeglumine. MATERIALS AND METHODS: Ninety-five gadobenate-enhanced magnetic resonance imaging studies were retrospectively and independently analyzed. The effects of selective hepatic enhancement and biliary excretion were each categorized into 3 grades according to the perceived difference of signal intensity between the liver parenchyma and portal vein, and signal intensity in the common bile duct of precontrast- and delayed-phase images.History of diffuse liver disease, liver cirrhosis, and renal disease; elevated levels of blood urea nitrogen (BUN)/creatinine (Cr), aspartate aminotransferase (AST)/alanine aminotransferase, bilirubin, and alkaline phosphatase (ALP); ascites; and splenomegaly were compared according to the grade of hepatic and biliary enhancement. RESULTS: Diffuse liver disease (P = 0.002); cirrhosis (P < 0.001); renal disease (P = 0.022); ascites (P = 0.001); splenomegaly (P < 0.001); and elevated levels of BUN (P = 0.001), Cr (P = 0.003), AST (P < 0.001), bilirubin (P < 0.001), and ALP (P < 0.001) were factors that impaired selective hepatic enhancement. Biliary excretion was affected by the presence of liver disease (P < 0.001), cirrhosis (P < 0.001), splenomegaly (P < 0.001), ascites (P = 0.002), and elevated levels of Cr (P = 0.013), AST (<0.001), alanine aminotransferase (P = 0.001), bilirubin (P < 0.001), and ALP (P < 0.001). CONCLUSION: Delayed selective hepatobiliary enhancement of gadobenate dimeglumine can be impaired by liver or renal disease and/or by elevated levels of bilirubin, ALP, BUN, and Cr.

Typical and atypical manifestations of serous cystadenoma of the pancreas: imaging findings with pathologic correlation.

OBJECTIVE: The purpose of this article is to present the typical and atypical manifestations of serous cystadenoma, which can be visualized with cross-sectional imaging. CONCLUSION: Serous cystadenomas of the pancreas have various distinguishing imaging features. Typically, a serous cystadenoma is morphologically classified as having either a polycystic, honeycomb, or oligocystic pattern. Atypical manifestations of serous cystadenoma can include giant tumors with ductal dilatation, intratumoral hemorrhages, solid variants, unilocular cystic tumors, interval growth, and a disseminated form.

Greater and lesser omenta: normal anatomy and pathologic processes.

The peritoneum is the largest serous membrane in the body and the one with the most complex structure. The omentum is a double-layered extension of the peritoneum that connects the stomach to adjacent organs. The peritoneal reflections form the greater and lesser omenta, and the natural flow of peritoneal fluid determines the route of spread of intraperitoneal fluid and consequently of disease processes within the abdominal cavity. The omenta serve both as boundaries for disease processes and as conduits for disease spread. The omenta are frequently involved by infectious, inflammatory, neoplastic, vascular, and traumatic processes. Computed tomography (CT) is a primary diagnostic method for evaluation of omental diseases, most of which may manifest with nonspecific clinical features. Multidetector CT with multiplanar reformation allows accurate examination of the complex anatomy of the peritoneal cavity, knowledge of which is the key to understanding the pathologic processes affecting the greater and lesser omenta.

Comparison of CT and 18F-FDG pet for detecting peritoneal metastasis on the preoperative evaluation for gastric carcinoma.

OBJECTIVE: The aim of our study was to compare the accuracy of CT and (18)FFDG PET for detecting peritoneal metastasis in patients with gastric carcinoma. MATERIALS AND METHODS: One-hundred-twelve patients who underwent a histologic confirmative exam or treatment (laparotomy, n = 107; diagnostic laparoscopy, n = 4; peritoneal washing cytology, n = 1) were retrospectively enrolled. All the patients underwent CT and (18)F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and (18)FFDG PET imaging for the detection of peritoneal metastasis were calculated and then compared using Fisher's exact probability test (p < 0.05), on the basis of the original preoperative reports. In addition, two board-certified radiologists and two board-certified nuclear medicine physicians independently reviewed the CT and PET scans, respectively. A receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of CT and (18)F-FDG PET imaging for detecting peritoneal metastasis. RESULTS: Based on the original preoperative reports, CT and (18)F-FDG PET showed sensitivities of 76.5% and 35.3% (p = 0.037), specificities of 91.6% and 98.9% (p = 0.035), respectively, and equal accuracies of 89.3% (p = 1.0). The receptor operating characteristics curve analysis showed a significantly higher diagnostic performance for CT (Az = 0.878) than for PET (Az = 0.686) (p = 0.004). The interobserver agreement for detecting peritoneal metastasis was good (kappa value = 0.684) for CT and moderate (kappa value = 0.460) for PET. CONCLUSION: For the detection of peritoneal metastasis, CT was more sensitive and showed a higher diagnostic performance than PET, although CT had a relatively lower specificity than did PET.

Detection of hepatic metastasis: manganese- and ferucarbotran-enhanced MR imaging.

PURPOSE: To compare the mangafodipir trisodium (MnDPDP)-enhanced and ferucarbotran-enhanced magnetic resonance imaging (MRI) for the detection of hepatic metastases. MATERIAL AND METHODS: Twenty patients with known hepatic metastasis underwent MR imaging using mangafodipir trisodium and ferucarbotran in at least 1-day intervals. Thirty-eight metastases were confirmed either histologically or clinically. Two radiologists independently reviewed the MnDPDP-enhanced and ferucarbotran-enhanced sets in a random order. The sensitivity and accuracy of lesion detection and the ability to distinguish a benign lesion from a malignant lesion were compared by the areas (Az) under the receiver operating characteristic (ROC) curve. The lesion-liver contrast-to-noise ratios (CNR) were compared by paired t-test. RESULTS: The overall accuracy for detecting metastases was not significantly different between the MnDPDP set (Az=0.912 and 0.913 for reader 1 and 2, respectively) and the SPIO set (Az=0.920 and 0.950). The CNR at the MnDPDP-enhanced images and the SPIO-enhanced images were not significantly different (P=0.146). CONCLUSION: Both MnDPDP- and ferucarbotran-enhanced MRI have a comparable accuracy in detecting hepatic metastasis.

Solid pseudopapillary tumor of the pancreas: typical and atypical manifestations.

OBJECTIVE: The purpose of this pictorial essay is to illustrate the various appearances of solid pseudopapillary tumor of the pancreas. CONCLUSION: Solid pseudopapillary tumor of the pancreas is a rare neoplasm usually found in young women. Typical solid pseudopapillary tumor is characterized by a well-encapsulated mass with varying amounts of intratumoral hemorrhage. However, the tumor can have an atypical appearance, such as metastasis, ductal obstruction, parenchymal and extracapsular invasion, simulation of islet cell tumor, intratumoral calcification, and occurrence in a male patient. The typical and atypical manifestations of solid pseudopapillary tumor can be visualized with cross-sectional imaging.

Preoperative MRI of potential living-donor-related liver transplantation using a single dose of gadobenate dimeglumine.

OBJECTIVE: This article evaluates the feasibility of single-dose gadobenate dimeglumine-enhanced MRI as both an angiographic and biliary contrast medium for making a preoperative evaluation of the donor candidates for a living-donor-related liver transplantation. SUBJECTS AND METHODS: Eleven right hepatic lobe donors underwent MRI examinations using T1- and T2-weighted imaging and T2-weighted MR cholangiography (MRC). The MR angiography (MRA) and contrast-enhanced (CE) T1-weighted MRC images then were obtained after injecting a single dose of gadobenate dimeglumine. One radiologist and one surgeon prospectively reviewed all the MRI examinations for hepatic vascular and biliary abnormalities and compared them with the surgical findings and intraoperative cholangiograms. In addition, two blinded reviewers evaluated the two sets of MRC (T2-weighted MRC set and T2-weighted MRC plus CE-T1-weighted MRC set) retrospectively and recorded the anatomic types of the hilar biliary branching pattern along with their confidence in the interpretation. RESULTS: Prospective analysis detected the following vascular variants: hepatic arterial variation in two patients, portal venous variation in one, and a significantly large accessory hepatic vein (> 5 mm) in one. Biliary variants also were identified in two patients. All the MRI findings on the vascular and biliary anatomy were corroborated intraoperatively. Retrospective analysis showed that the mean diagnostic confidence in the combined set was significantly higher than that of the T2-weighted MRC alone by both reviewers (p < 0.05). CONCLUSION: Obtaining both MRA and CE-T1-weighted MRC is feasible using a single dose of gadobenate dimeglumine. Therefore, gadobenate dimeglumine-enhanced MRI might play a role as a preoperative imaging technique for the vascular and biliary evaluation of potential living donors.

Comparison of unmonochromatized synchrotron radiation and conventional X-rays in the imaging of mammographic phantom and human breast specimens: a preliminary result.

A simple imaging setup based on the principle of coherence-based contrast X-ray imaging with unmonochromatized synchrotron radiation was used for studying mammographic phantom and human breast specimens. The use of unmonochromatized synchrotron radiation simplifies the instrumentation, decreases the cost and makes the procedure simpler and potentially more suitable for clinical applications. The imaging systems consisted of changeable silicon wafer attenuators, a tungsten slit system, a CdWO4 scintillator screen, a CCD (Charge Coupled Device) camera coupled to optical magnification lenses, and a personal computer. In preliminary studies, a spatial resolution test pattern and glass capillary filled with air bubbles were imaged to evaluate the resOolution characteristics and coherence-based contrast enhancement. Both the spatial resolution and image quality of the proposed system were compared with those of a conventional mammography system in order to establish the characteristic advantages of this approach. The images obtained with the proposed system showed a resolution of at least 25 microm on the test pattern with much better contrast, while the images of the capillary filled with air bubbles revealed coherence-based edge enhancement. This result shows that the coherence-based contrast imaging system, which emphasizes the refraction effect from the edge of materials of different refractive indexes, is applicable to imaging studies in fundamental medicine and biology, although further research works will be required before it can be used for clinical applications.

Early biliary complications of laparoscopic cholecystectomy: evaluation on T2-weighted MR cholangiography in conjunction with mangafodipir trisodium-enhanced 3D T1-weighted MR cholangiography.

OBJECTIVE: Our aim was to assess preliminary experience with combined conventional T2-weighted and mangafodipir trisodium (MnDPDP)-enhanced T1-weighted MR cholangiography in evaluating early biliary complications of laparoscopic cholecystectomy. SUBJECTS AND METHODS: Conventional heavily T2-weighted MR cholangiography with MnDPDP-enhanced T1-weighted MR cholangiography and ERCP were performed in seven patients with high clinical suspicion of biliary complications after laparoscopic cholecystectomy. The final diagnoses of complications were classified according to the presence and degree of bile duct injury, bile leakage, and retained stones. RESULTS: The diagnoses on MR cholangiography were as follows: complete transection and occlusion of the common bile duct with bile leakage (n = 3), partial strictures of the common bile duct with bile leakage (n = 1), cystic duct leakage (n = 1), partial ligation of an aberrant right hepatic duct (n = 1), and hemorrhage without biliary complication (n = 1). The final diagnoses at surgery (n = 2) and ERCP (n = 5) were as follows: complete transection and occlusion of the common bile duct with bile leakage (n = 2), partial strictures of the common bile duct with bile leakage (n = 2), cystic duct leakage (n = 1), partial ligation of an aberrant right hepatic duct (n = 1), and hemorrhage without biliary complication (n = 1). MR cholangiography accurately yielded the same findings as the final diagnoses, except in one case with partial stricture of the bile duct with bile leakage (overdiagnosed as complete occlusion on MR cholangiography). CONCLUSION: Combined conventional T2-weighted and MnDPDP-enhanced T1-weighted MR cholangiography may eliminate the use of other studies for the imaging of biliary complications after cholecystectomy if this preliminary data can be verified in a larger study.

Annular pancreas: emphasis on magnetic resonance cholangiopancreatography findings.

An annular pancreas is a rare congenital anomaly in which a portion of the pancreatic tissue surrounds the duodenum. Magnetic resonance cholangiopancreatography (MRCP) is used extensively for evaluating the pancreatobiliary ducts. There have been only few cases in which MRCP clearly demonstrated the types of annular ducts, however. Two cases of an annular pancreas based on a new classification of the morphologic type are reported.

Ultrasound-guided fine-needle aspiration biopsy in nonpalpable thyroid nodules: is it useful in infracentimetric nodules?

The purpose of this study was to evaluate the usefulness of an ultrasound-guided fine-needle aspiration biopsy (US-FNAB) for the evaluation and treatment planning of nonpalpable thyroid lesions, including infracentimetric nodules. One hundred and twenty one patients underwent US-FNAB for 149 non-palpable solid nodules. Sixty-five patients underwent surgery, and 84 were followed up for at least 36 months. The results of the US-FNAB correlated with the pathological findings and clinical follow-up results. The nodules ranged from 0.3 to 2 cm in diameter, with a mean of 0.8 cm. Among the 149 nodules, 115 were infracentimetric and 34 were centimetric or supracentimetric in size. Of the 149 thyroid nodules, US-FNAB was true positive in 43, true negative in 90, false positive in 7 and false negative in 1. In 8 cases, the lesion was inadequately sampled. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the US-FNAB for the infracentimetric nodules were 96.9, 93.4, 86.1, 98.6 and 94.4%, and for the centimetric or supracentimetric nodules, were 100, 90.5, 85.7, 100 and 93.9%, respectively. There were no significant differences in the results between the infracentimetric and centimetric or supracentimetric nodules. In conclusion, an US-FNAB is a useful tool for determining the treatment plan of non-palpable solid thyroid nodules, even when less than 1 cm in diameter, and shows high sensitivity, specificity and accuracy.

Imaging findings of giant liposarcoma of the esophagus.

A giant esophageal liposarcoma showing rapid growth over 7 months is presented in 56-year-old man. It originated from the pharyngo-esophageal junction with a short stalk, and extended downward to the distal esophagus. A barium swallow study showed a large, sausage-like intraluminal mass in the dilated esophagus. CT and MR imaging showed a heterogeneous mass with a fatty component in the esophagus. A total laryngopharyngo-esophagectomy was performed and the histological diagnosis was of a well-differentiated liposarcoma.

Fat sparing of surrounding liver from metastasis in patients with fatty liver: MR imaging with histopathologic correlation.

OBJECTIVE: The purpose of our study was to evaluate the characteristic MR imaging findings and histopathologic correlation of peritumoral fat sparing of liver metastasis in patients with fatty liver. CONCLUSION: Out-of-phase spoiled gradient-echo MR imaging was useful in detecting and characterizing the peritumoral fat sparing of liver metastasis in patients with fatty liver that was isointense to surrounding hepatic parenchyma on unenhanced in-phase spoiled gradient-echo, T2-weighted inversion recovery, and contrast-enhanced nonsuppressed spoiled gradient-echo MR imaging.

Supplemental transcatheter arterial chemoembolization through a collateral omental artery: treatment for hepatocellular carcinoma.

PURPOSE: To evaluate the therapeutic efficacy and safety of supplemental transcatheter arterial chemoembolization (TACE) through the extrahepatic collateral omental artery (OA) for the treatment of hepatocellular carcinoma (HCC). METHODS: We studied 21 patients with extrahepatic collaterals of the OA, among 1,512 patients with HCC who had undergone angiography. HCCs supplied by collateral OAs were located at: segment IV in seven, segment V in five, segment III in three, segment VI in three and segment VIII in three patients (Couinaud classification of segments). On preoperative CT scans, every HCC was abutting the liver surface. Adjacent omental infiltration or engorgement was noted in 11 patients. Celiac and hepatic arteriograms showed hypertrophy of the feeding OA in all patients. TACE of the OA was performed in 19 patients with an emulsion of iodized oil and doxorubicin hydrochloride. Embolization with gelatin sponge particles was added in five patients. RESULTS: Collaterals of the OA to the HCC were found on the first to seventeenth sessions of TACE. On follow-up CT scans, five patients showed complete uptake of iodized oil in the tumor. Partial uptake of iodized oil was noted in 13 patients and no uptake in one patient. There was no serious complication that related to the omental embolization, such as omental or bowel ischemia. The cumulative survival rates from the time of the TACE of the OA were 81% at 6 months and 68% at 12 months. CONCLUSION: TACE of the OA is safe and has a potential therapeutic effect in the treatment of HCC.

Differential diagnosis of periampullary carcinomas at MR imaging.

Periampullary carcinomas arise within 2 cm of the major duodenal papilla and comprise carcinomas of the ampulla, distal common bile duct, pancreas, and duodenum. Their clinical features and anatomic locations are similar, as are the therapeutic approaches; however, their long-term outcomes vary. Magnetic resonance (MR) images of 89 pathologically proved periampullary carcinomas (29 ampullary carcinomas, 27 distal common bile duct carcinomas, 21 pancreatic carcinomas, six duodenal carcinomas, and six unclassified carcinomas) were reviewed. Ampullary carcinoma manifests as a small mass, periductal thickening, or bulging of the duodenal papilla. Pancreatic carcinoma is characterized by a discrete parenchymal mass, which enhances poorly on dynamic gadolinium-enhanced images. Sometimes, two proximal and two distal pancreatic and biliary ducts appear as four separate ducts (the four-segment sign). Dilatation of side branches of the pancreatic ducts is frequently seen in pancreatic carcinoma but not in other periampullary carcinomas. Distal bile duct carcinoma manifests as luminal obliteration and wall thickening or as an intraductal polypoid mass. A dilated proximal bile duct, a nondilated distal bile duct, and a dilated or nondilated pancreatic duct may form the three-segment sign. MR cholangiopancreatography and sectional MR imaging are useful in determining the origins of periampullary carcinomas.

Radiographic findings of primary B-cell lymphoma of the stomach: low-grade versus high-grade malignancy in relation to the mucosa-associated lymphoid tissue concept.

OBJECTIVE: We undertook this study to assess how well double-contrast radiography and CT allow radiologists to differentiate low-grade from high-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach. MATERIALS AND METHODS: We retrospectively reviewed the upper gastrointestinal radiographs and contrast-enhanced CT scans of 57 patients with pathologically proven primary gastric lymphoma (low-grade [n = 29] and high-grade [n = 28] MALT lymphoma). RESULTS: On upper gastrointestinal radiography, ulceration (39%) was the most common finding in low-grade lymphoma, whereas polypoid appearance (38%) was the most common in high-grade lymphoma. In the 29 patients (33 lesions) with low-grade MALT lymphoma, upper gastrointestinal radiography revealed 13 ulcerative lesions (39%), 10 nodular lesions (30%), four infiltrative lesions (12%), two polypoid lesions (6%), and four combined lesions (12%). In the 28 patients (29 lesions) with high-grade lymphoma, upper gastrointestinal radiography revealed 11 polypoid lesions (38%), nine infiltrative lesions (31%), six ulcerative lesions (20%), one nodular lesion (3%), and two combined lesions (7%). On CT, thickening of the gastric wall in low-grade lymphoma (range, 0.3-2.5 cm; mean, 0.8 cm) was much less than that in high-grade lymphoma (range, 0.7-8.0 cm; mean, 2.5 cm). Abdominal lymphadenopathy was less frequent in low-grade lymphoma (14%) than in high-grade lymphoma (75%). CONCLUSION: Most low-grade lymphomas show superficial spreading lesions, such as mucosal nodularity, shallow ulcer, and minimal fold thickening, on upper gastrointestinal radiography, whereas most high-grade lymphomas show mass-forming lesions or severe fold thickening.

Clinical evaluation of compression ratios using JPEG2000 on computed radiography chest images.

The efficient compression of radiographic images is of importance for improved storage and network utilization in support of picture archiving and communication systems (PACS) applications. The DICOM Working Group 4 adopted JPEG2000 as an additional compression standard in Supplement 61 over the existing JPEG. The wavelet-based JPEG2000 can achieve higher compression ratios with less distortion than the Discrete Cosine Transform (DCT)-based JPEG algorithm. However, the degradation of JPEG2000-compressed computed radiography (CR) chest images has not been tested comprehensively clinically. The authors evaluated the diagnostic quality of JPEG2000-compressed CR chest images with compression ratios from 5:1 to 200:1. An ROC (receiver operating characteristic analysis) and t test were performed to ascertain clinical performance using the JPEG2000-compressed images. The authors found that compression ratios as high as 20:1 can be utilized without affecting lesion detectability. Significant differences between the original and the compressed CR images were not recognized up to compression ratio of 50:1 within a confidence level of 99%.

MR cholangiography in symptomatic gallstones: diagnostic accuracy according to clinical risk group.

PURPOSE: To determine the diagnostic accuracy of magnetic resonance (MR) cholangiography in the detection of common bile duct (CBD) stones in patients with symptomatic gallstones. MATERIALS AND METHODS: Single-shot half-Fourier MR cholangiographic images were obtained in 121 consecutive patients who were referred for MR cholangiography prior to cholecystectomy for symptomatic gallstones. One radiologist interpreted the MR cholangiographic images without prior knowledge of laboratory test results or findings from examinations with other imaging modalities. Patients were retrospectively divided into three groups with high, moderate, and low risk (n = 70, 22, and 29, respectively) for CBD stones. The sensitivity, specificity, and accuracy of MR cholangiography in the detection of CBD stones in each group were calculated. The accuracy of laboratory and sonographic findings in the identification of CBD stones was also calculated. RESULTS: CBD stones were diagnosed in 49 (70%) of 70 patients in the high-risk group. One false-positive diagnosis was made, and two false-negative diagnoses were made. Of the 22 patients in the moderate-risk group, seven (32%) had CBD stones, and there was one false-positive and one false-negative diagnosis. In the low-risk group, CBD stones were correctly identified with MR cholangiography in one patient, and there was one false-positive diagnosis. A combination of positive laboratory and sonographic findings yielded a sensitivity of 98% but a specificity of only 34% if any unusual finding in any one of the tests was regarded as a positive finding. CONCLUSION: MR cholangiography is highly accurate in the detection of CBD stones in all patients, regardless of the grade of risk, and should be considered in patients with a moderate to high risk of CBD stones before cholecystectomy.

Using MR cholangiopancreatography to reveal anomalous pancreaticobiliary ductal union in infants and children with choledochal cysts.

OBJECTIVE: The purpose of this study was to determine whether MR cholangiopancreatography can accurately depict anomalous pancreaticobiliary ductal union in children with choledochal cysts. SUBJECTS AND METHODS: Twenty children (age range, 1 month-13 years; mean age, 4.6 years; all girls) who were diagnosed with choledochal cyst by sonography underwent MR cholangiopancreatography with a single-shot fast spin-echo sequence. The type of choledochal cyst and anomalous pancreaticobiliary ductal union were characterized on the basis of MR cholangiopancreatographic findings and were compared with the finding of intraoperative cholangiography. RESULTS: The type of choledochal cyst (type Ia, n = 4; type Ic, n = 7; type IVa, n = 7; type IVb, n = 2) determined on MR cholangiopancreatography correlated with that identified on intraoperative cholangiography in each patient. Anomalous pancreaticobiliary ductal union was detected by MR cholangiopancreatography and intraoperative cholangiography in 12 (60%) and 16 (80%) of 20 patients, respectively. The types of anomalous pancreaticobiliary ductal union as determined on MR cholangiopancreatography (type A, n = 2; type B, n = 7; type C, n = 3) were concordant with those of intraoperative cholangiography in 11 of 12 patients. In five of eight patients with choledochal cyst (type Ia, n = 1; type IVa, n = 5; type IVb, n = 2) in whom MR cholangiopancreatography could not depict anomalous pancreaticobiliary ductal union, anomalous pancreaticobiliary ductal union was documented on intraoperative cholangiography that was performed after choledochal cyst resection. CONCLUSION: MR cholangiopancreatography provides diagnostic information about anomalous pancreaticobiliary ductal union in children with choledochal cyst.