Enhancement characteristics of cholangiocarcinomas on mutiphasic helical CT: emphasis on morphologic subtypes.

PURPOSE: The purpose of this study was to characterize the differences in CT enhancement pattern among the morphologic subtypes of cholangiocarcinomas. MATERIALS AND METHODS: Unenhanced, hepatic arterial (HAP), and portal venous phase (PVP) CT images of 84 patients with pathologically proven cholangiocarcinoma were retrospectively reviewed. Tumors were of the following types: 27 mass-forming, 39 periductal-infiltrating, and 18 intraductal. The CT attenuation values of tumors were measured at each phase. The tumor enhancement ratio (ER) on HAP and PVP was calculated. RESULTS: Each cholangiocarcinoma subtype produced characteristic enhancement relative to liver on HAP and PVP images: mass-forming tumors demonstrated hyperenhancing periphery and hyopenhancing centers; periductal-infiltrating tumors, hyperenhancing; and intraductal tumors, hypoenhancing. The ER of the tumor types was significantly different (P<.001, HAP, PVP): periductal-infiltrating tumors showed the highest ER (2.5; 3.8); the centers of mass-forming tumors, lowest (1.5; 2.2); the peripheries of mass-forming tumors, high (2.1; 3.0); intraductal tumors, low (1.9; 2.6). CONCLUSION: Cholangiocarcinoma subtypes tended to exhibit distinct enhancement characteristics. Knowledge of these enhancement patterns may aid diagnosis and surgical planning.

Radiologic and pathologic findings of nonpalpable thyroid carcinomas detected by ultrasonography in a medical screening center.

OBJECTIVE: The purpose of this study was to investigate the ultrasonographic and pathologic findings of nonpalpable thyroid carcinomas and reliable guidelines for fine-needle aspiration (FNA). METHODS: Our study was approved by our Institutional Review Board, and written informed consent was waived. Between April 2004 and June 2006, screening ultrasonography was performed for 16,352 self-referred patients in the health care center. Among 1325 nonpalpable thyroid nodules in 1009 patients, pathologic results of FNA revealed 823 benign, 154 indeterminate, 198 nondiagnostic, and 150 malignant nodules. Fifty-eight malignant thyroid nodules (39 microcarcionomas and 19 carcinomas >1 cm, confirmed by both FNA and thyroidectomy) in 55 patients and 82 benign nodules (confirmed by both FNA and follow-up over 2 years) in 75 patients were included for the analysis. Three radiologists retrospectively analyzed the ultrasonographic features of these nonpalpable thyroid nodules for echogenicity, shape, margin, calcification, degree of cystic changes, and size. We compared the radiologic and pathologic findings between microcarcinomas and carcinomas larger than 1 cm for extra-capsular invasion, lymph node metastasis, bilaterality, and multicentricity using univariate analysis. RESULTS: Marked hypoechogenicity, an irregular shape, a taller-than-wide shape, a well-defined spiculated margin, microcalcification, and an entirely solid nature were significant predictors for malignancy (P < .05), whereas a cutoff value of 1 cm in the longest diameter was not significant (P = .184). However, extracapsular invasion (P = .024) and lymph node metastasis (P = .019) were observed more frequently in carcinomas larger than 1 cm (73.7% and 42.1%, respectively) than in microcarcinomas (38.5% and 12.8%). CONCLUSIONS: Ultrasonographic findings suggesting malignancy should be preferentially considered as indicators for FNA, regardless of size, in nonpalpable thyroid nodules. However, extracapsular invasion and lymph node metastasis are closely related to the size of the thyroid nodule.

Macrocystic neoplasms of the pancreas: CT differentiation of serous oligocystic adenoma from mucinous cystadenoma and intraductal papillary mucinous tumor.

OBJECTIVE: The purpose of our study was to determine useful CT criteria for differentiating serous oligocystic adenomas of the pancreas from other similarly presenting neoplasms, such as mucinous cystadenoma and intraductal papillary mucinous tumor of the branch duct type. MATERIALS AND METHODS: Forty-one patients with histologically confirmed macrocystic neoplasms of the pancreas were enrolled: serous oligocystic adenoma in 10 patients, mucinous cystadenoma in 13, and intraductal papillary mucinous tumor in 18. Location, greatest dimension, shape, presence of mural nodules, presence of wall calcification, and the extent and degree of main pancreatic duct (MPD) dilatation were analyzed with CT. The lesions were categorized into seven groups according to their shapes: multicystic, lobulated contour with and without internal septation, smooth contour with and without internal septation, pleomorphic cystic, and clubbed fingerlike cystic. Comparative studies were performed using Fisher's exact test and the Mann-Whitney U test. RESULTS: Significant differences in lesion shape were found between serous oligocystic adenoma and the other macrocystic neoplasms (mucinous cystadenoma [p < 0.05], intraductal papillary mucinous tumor [p < 0.05]). Serous oligocystic adenoma had a multicystic or lobulated contour with or without septation, whereas mucinous cystadenoma had a smooth contour with or without septation and intraductal papillary mucinous tumor had either a pleomorphic or a clubbed fingerlike cystic shape. Serous oligocystic adenoma showed proximal MPD dilatation from the lesion, whereas intraductal papillary mucinous tumor showed distal or whole MPD dilatation (p < 0.05). No significant difference was apparent among the three diseases in terms of location, greatest dimension, or presence of calcification or mural nodules. CONCLUSION: Serous oligocystic adenoma of the pancreas has characteristic CT findings that differentiate it from other cystic tumors. It appears as a multicystic or lobulated cystic lesion with septation.

Gadobenate dimeglumine-enhanced liver MRI as the sole preoperative imaging technique: a prospective study of living liver donors.

OBJECTIVE: The objective of our study was to determine whether gadobenate dimeglumine-enhanced MRI is practical as the sole preoperative imaging technique for the examination of living liver donors. SUBJECTS AND METHODS: Forty-four consecutive living donor candidates underwent liver MRI on a 1.5-T MR unit. The MR examination included in- and opposed-phase T1-weighted gradient-echo imaging, T2-weighted MR cholangiography, MR angiography (MRA) and parenchymal phase imaging after the administration of gadobenate dimeglumine, and 60-minute delayed T1-weighted MR cholangiography. Two abdominal radiologists analyzed the images regarding the depiction of the biliary duct anatomy and the hepatic vascular anatomy and for the presence of focal or diffuse liver disease. The findings were compared with intraoperative cholangiographic and surgical findings in 24 patients who underwent partial hepatectomy. RESULTS: In the 24 patients who underwent liver harvesting, 10 had biliary anatomic variants confirmed by intraoperative cholangiography. T2-weighted MR cholangiography allowed a correct diagnosis in 75% (n = 18/24) and T1-weighted MR cholangiography in 79% (n = 19/24) of these patients. When we evaluated the bile duct anatomy using the combined findings of T2- and T1-weighted MR cholangiographic images, the diagnostic accuracy increased to 92% (n = 22/24), but the difference was not statistically significant (p > 0.05). MRA showed a diagnostic accuracy of 79% (n = 19/24) for the hepatic arterial anatomy, 100% (n = 24/24) for the portal venous anatomy, and 96% (n = 23/24) for the hepatic venous anatomy. CONCLUSION: Gadobenate dimeglumine-enhanced MRI allows comprehensive assessment of the biliary and hepatic vascular systems and the hepatic parenchyma and can serve as the sole preoperative imaging test for living liver donor candidates.

Percutaneous drainage of postoperative abdominal abscess with limited accessibility: preexisting surgical drains as alternative access route.

PURPOSE: To retrospectively assess the effectiveness and safety of postoperative percutaneous drainage of abdominal abscesses with limited accessibility by using a preexisting surgical drain as an access route. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was not required. The authors reviewed the medical records of 92 patients (62 male, 30 female; median age, 59 years; age range, 3-79 years) with postoperative abdominal abscesses in whom percutaneous drainage was performed by using surgical drains as an access. Factors evaluated included the location and size of the lesion; time between surgery and the drainage procedure; distance between the lesion and surgical drain; presence of fistula; duration of drainage; type of surgical drain; size, type, and length of drainage catheter; and complications. Technical success was defined as adequate placement of a new drainage catheter into the target abscess. Midterm success was defined as avoidance of surgery or additional percutaneous drainage during the 6 months of follow-up. Univariate analysis and multiple logistic regression analysis were performed to determine factors that affected the technical or midterm success of the procedure. RESULTS: Of 92 postoperative abscesses for which the technique was attempted, 56 (61%) had a subphrenic location and 36 (39%) had a peripancreatic location. Technical success was achieved in 87 of the 92 patients (95%). Technical success was not significantly associated with any of the factors tested. Midterm success was achieved in 75 of the 87 patients (86%) in whom technical success was achieved. Midterm failure showed a statistically significant relationship with the presence of fistula (P = .04). No procedure-related complications were identified. CONCLUSION: Percutaneous drainage by using the surgical drain as an access route is an effective and safe alternative for draining postoperative abdominal abscesses that are less accessible with direct puncture..

Small-bowel obstruction in a phantom model of ex vivo porcine intestine: comparison of PACS stack and tile modes for CT interpretation.

PURPOSE: To compare computed tomographic (CT) image interpretation with picture archiving and communication systems (PACS) stack and tile modes for speed and accuracy of transition zone localization in small-bowel obstruction by using ex vivo porcine specimens. MATERIALS AND METHODS: Twenty-five small-bowel obstruction phantom models made of ex vivo porcine intestines from a slaughterhouse were imaged at CT. One was used for observer training, and 24 were used for experimentation. At 20-cm intervals throughout the intestines, metallic markers were placed in the mesenteries immediately adjacent to bowel. One obstruction was made in each intestine, midway between markers, by ligating intestine with a 3-0 silk suture to simulate mechanical small-bowel obstruction. The lumen proximal to the ligation site was distended with air and a soybean oil-iodized oil mixture until at least two-thirds of the proximal intestine exceeded 2.0 cm in transverse diameter. Dilated segments were 310-550 cm in length. Soybean oil and a mixture of soybean and iodized oil were used to simulate differences in attenuation among bowel wall, intraluminal fluid, and extraluminal abdominal fat. Four experienced abdominal radiologists independently determined the transition zone by using stack mode (cine viewing of stacked images) and, at least 2 weeks later, tile mode (side-by-side image display). Accuracy and degree of error in counting markers were evaluated, and speed of interpretation was recorded. Statistical analysis was performed with the McNemar and Wilcoxon signed rank tests. RESULTS: For all observers, accuracy of transition zone localization tended to be better with stack mode (63%-83% [15-20 phantoms]) than with tile mode (50%-63% [12-15 phantoms]), but the differences were not significant. For each observer, mean counting error was lower in stack mode (range, 0.96-2.48) than in tile mode (range, 1.74-3.22), with significance for three observers (P < .01, P < .01, and P = .04). Interpretation was significantly faster with stack mode by a factor of two to three for all observers (P < .01). CONCLUSION: Stack mode evaluation for identification of the transition zone in obstructed small bowel is faster than evaluation with tile mode. Accuracy is not significantly different between modes, although there is a tendency toward better results with stack mode.

Wet radio-frequency ablation using multiple electrodes: comparative study of bipolar versus monopolar modes in the bovine liver.

OBJECTIVE: To determine whether hypertonic saline (HS)-mediated bipolar radio-frequency (rf) application as advantages over monopolar simultaneous and alternating rf applications for creating larger areas of coagulation necrosis. MATERIALS AND METHODS: A total of 60 rf ablations using double perfused-cooled electrodes and a 200 W generator (CC-3 model, Radionics) were performed in three different modes in explanted bovine livers: simultaneous monopolar mode (groups A and A'); alternating monopolar mode (groups B and B'); or bipolar mode (groups C and C'). Electrodes were placed at inter-electrode distances of 3 and 5 cm, and HS (6% NaCl solution) was instilled into tissue at a rate of 1 mL/min through the electrodes. rf was applied for 10 (3 cm distance) or 15 min (5 cm distance). During rf application, we measured the tissue temperature at the mid-point between the two electrodes. Dimensions of the thermal ablation zones, and temperatures were compared between the 3 groups using analysis of variance or the Kruskal-Wallis test. To compare configurations of the ablation zones in each group, the ratio of longitudinal diameter (Dl) to vertical diameter (D(v)) was calculated. RESULTS: With a 3-cm inter-electrode spacing, the D(v) between the electrodes of ablated lesions was 2.4 +/- 1.2 cm in group A, 4.5 +/- 1.0 cm in group B, and 6.1 +/- 0.9 cm in group C (P < 0.05), and at a 5-cm spacing, groups B' and C' produced a single ablation area, but group A' produced two separated ablation spheres: the D(v)s were 1.4 +/- 0.2 in group A, 2.9 +/- 1.0 mm in group B, and 6.6 +/- 0.4 cm in group C (P < 0.05). For both 5- and 3-cm spacings, the temperatures at the mid-point were higher in bipolar mode than in either monopolar simultaneous or alternating modes. The ratios of Dl/D(v) of groups A, B, and C were 2.5 +/- 0.2, 1.4 +/- 0.1, and 1.1 +/- 0.1, respectively, and the corresponding figures of groups A', B' and C' were 4.5 +/- 0.2, 2.7 +/- 0.1, and 1.1 +/- 0.1, respectively (P < 0.05). CONCLUSION: HS-enhanced bipolar rf ablation creates larger, more regular coagulation necrosis than either monopolar simultaneous or alternating rf ablation.

Value of contrast-enhanced sonography for the characterization of focal hepatic lesions in patients with diffuse liver disease: receiver operating characteristic analysis.

OBJECTIVE: Our aim was to assess the diagnostic performance of contrast-enhanced agent detection sonographic imaging to characterize focal hepatic lesions in patients with diffuse liver disease in comparison with baseline sonographic images and to determine whether agent detection imaging can reduce the necessity of further diagnostic workup for lesion characterization. MATERIALS AND METHODS: Contrast-enhanced sonography using 4 g of Levovist at a concentration of 300 mg/mL was performed on 75 focal hepatic lesions in 75 patients with diffuse liver disease. Interval reviews for both baseline without and with contrast-enhanced sonography were performed independently by two radiologists. They were requested to determine the malignity of focal hepatic lesions using a 5-point confidence level and to record the specific diagnoses and the necessity for further imaging for lesion characterization. Radiologists' performances for lesion differentiation using baseline and contrast-enhanced sonography were evaluated using receiver operating characteristic (ROC) analysis. Interobserver agreement was also analyzed. RESULTS: When contrast-enhanced sonography was used, ROC analysis revealed a significant improvement for both reviewers (area under the receiver operating characteristic curve [A(z)] = 0.753 and 0.830 and 0.971 and 0.974 at baseline sonography and contrast-enhanced sonography, respectively; p < 0.002) for differentiating malignant and benign focal liver lesions. Contrast-enhanced sonography also improved specificity from 12% to 91% for reviewer 1 and from 26% to 85% for reviewer 2 compared with baseline sonography. Furthermore, excellent interobserver agreement was achieved for contrast-enhanced sonography (weighted kappa = 0.919), whereas only good agreement was achieved for baseline sonography (weighted kappa = 0.656). A better result for specific diagnosis was obtained by contrast-enhanced sonography (79% and 75%) than by baseline sonography (37% and 48%, p < 0.05). Contrast-enhanced sonography (72% and 63%) outperformed baseline sonography (35% and 28%, p < 0.05) as a confirmatory imaging technique. CONCLUSION: Contrast-enhanced agent detection sonography can be used to characterize focal hepatic lesions in patients with diffuse liver disease reliably and with a higher diagnostic confidence than baseline sonography. Furthermore, contrast-enhanced sonography reduced the need for further diagnostic workups for focal hepatic lesion characterization.

Appropriateness of a donor liver with respect to macrosteatosis: application of artificial neural networks to US images--initial experience.

PURPOSE: To retrospectively compare performance of artificial neural networks (ANNs) applied to ultrasonographic (US) images with that of radiologists for prediction of appropriateness of a donor liver with respect to macrosteatosis before liver transplantation. MATERIALS AND METHODS: Institutional ethics committee approved study; written informed consent was obtained. ANNs, constructed with three-layered 15-neuron back-propagation algorithm, were trained to predict appropriateness of a donor liver with respect to macrosteatosis by using statistically significant laboratory and US parameters derived from univariate analyses, together with correct diagnosis. Input variables for ANNs were alkaline phosphatase, glutamic oxaloacetic transaminase, glutamic pyruvate transaminase, gamma-glutamyltransferase, hepatorenal ratio of echogenicity, and tail area ratio and tail length of portal vein wall echogenicity. Three radiologists graded US images in 94 potential donors (71 men and 23 women) on the basis of four degrees of hepatic steatosis. After training and testing of ANNs, performance of ANNs and radiologists in predicting appropriateness of potential donors was evaluated with receiver operating characteristic (ROC) analysis and compared by means of univariate z score test. RESULTS: Among 94 potential donor livers, 76 were normal or had mild steatosis, and 18 had moderate or severe macrosteatosis at histopathologic examination. Area under ROC curve (Az) of ANNs (Az=0.9673) was significantly greater than that of radiologists (faculty, Az=0.9106, P=.048; fellow, Az= 0.9038, P=.044; resident, Az=0.8931, P=.038). No statistically significant difference in sensitivity for predicting appropriateness as a liver donor with respect to macrosteatosis was found between ANNs (88.9%) and radiologists (P >.05). However, specificity of ANNs (96.1%) was significantly better than that of radiologists (P <.003). CONCLUSION: ANNs might be a useful tool to categorize whether a donor liver is appropriate for transplantation with respect to macrosteatosis on the basis of multiple variables related to laboratory and US features. Further study is needed.

Bipolar radiofrequency ablation using wet-cooled electrodes: an in vitro experimental study in bovine liver.

OBJECTIVE: Our aim was to evaluate the performance of hypertonic saline (HS)-enhanced bipolar radiofrequency ablation using wet-cooled electrodes versus monopolar radiofrequency ablation to create coagulation necrosis in explanted bovine liver. CONCLUSION: HS-enhanced bipolar radiofrequency ablation using the wet-cooled electrodes shows better performance in creating coagulation necrosis than the monopolar mode.

Sonographic features of an intraductal polypoid mass: differentiation between hepatocellular carcinoma and intraductal cholangiocarcinoma.

OBJECTIVE: To identify laboratory and sonographic features capable of differentiating hepatocellular carcinoma (HCC) invading the bile duct from intraductal cholangiocarcinoma (IDCCC). METHODS: Nine patients with HCC invading the bile duct and 8 patients with IDCCC were found in our radiologic and pathologic database. Laboratory (alpha-fetoprotein, cancer antigen 19-9, total bilirubin, and alkaline phosphatase) and sonographic findings were retrospectively reviewed by 2 reviewers by consensus. Sonographic findings included the presence and echo texture of parenchymal masses, the margin and echo texture of intraductal masses, continuity between parenchymal and intraductal masses, cystic ductal dilatation or wall thickening of the bile duct, and the presence of associated chronic liver disease. RESULTS: Significant differences were found in the levels of total bilirubin (14 versus 3.5 mg/dL), alpha-fetoprotein (2984 versus 5 ng/mL), and cancer antigen 19-9 (8574 versus 1861 U/mL) in HCC and IDCCC (P <.05). Echogenicity of the intraductal masses was iso or low in 8 (88.9%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs (P <.05). In all 7 patients with HCC but in no patient with IDCCC, the parenchymal masses were contiguous with the intraductal masses (P <.05). Cystic ductal dilatation of bile duct was seen in 8 (88.9%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs (P <.05). All 9 (100%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs were associated with chronic liver disease (P <.05). Parenchymal masses occurred in 7 patients with HCC (77.8%) and in 3 patients with IDCCC (37.5%), but the difference was not statistically significant (P =.153). The margins of the intraductal masses were smooth in all 9 (100%) of 9 HCCs and lobulated in 3 (37.5%) of 8 IDCCCs (P =.082). CONCLUSIONS: Combined interpretation of laboratory and sonographic features may help in the differentiation of HCC with bile duct invasion and IDCCC.

Relationship between various patterns of transient increased hepatic attenuation on CT and portal vein thrombosis related to acute cholecystitis.

OBJECTIVE: We sought to investigate the prevalence of portal vein thrombosis in patients with acute cholecystitis and the relationship between portal vein thrombosis and the various patterns of transient increased hepatic attenuation on CT. MATERIALS AND METHODS: We studied 72 of 107 patients with acute cholecystitis who, during a 3-year period, underwent dual-phase contrast-enhanced CT before percutaneous cholecystostomy or cholecystectomy. CT scans were retrospectively reviewed for the presence of portal vein thrombosis and location of the thrombi and for patterns of transient increased hepatic attenuation, which were classified as either pericholecystic, segmental, or mixed. RESULTS: Portal vein thrombi (two in hepatic segment IV, three in the left portal vein, and one in the right posterior portal vein) were found in six (8.3%) of 72 patients, and in those patients, transient increased attenuation with a segmental (five patients) or mixed (one patient) pattern was seen on CT. The pattern of transient increased attenuation in the 54 patients without portal vein thrombosis was pericholecystic in 41 (75.9%) and mixed in 13 (24.1%). Nineteen patients had segmental distribution (segmental or mixed pattern) that in 31.6% (6/19) of the patients was associated with portal vein thrombosis. Segmental distribution was more frequently found in those patients who had acute cholecystitis with portal vein thrombosis than in those who had only acute cholecystitis (p = 0.001). CONCLUSION: In patients with acute cholecystitis, portal vein thrombosis is not uncommon. Patterns of transient increased hepatic attenuation were found to vary, depending on the presence or absence of portal vein thrombosis.

Four-dimensional volume contrast ultrasound imaging of the gallbladder compared with tissue harmonic imaging: preliminary experience.

Comparison of volume contrast US imaging with tissue harmonic imaging for the evaluation of gallbladder lesions and determination of the adequate slice thickness in volume contrast US imaging were performed. Forty-one patients who had gallbladder lesions (polyps in 26, stones in 12, and sludge in 3) were enrolled in our study. A Voluson 730 Expert US scanner was used throughout. Volume contrast US imaging with slice thicknesses of 3, 5, 10 and 15 mm and tissue harmonic imaging of the gallbladder were obtained. Two abdominal radiologists reviewed the masked images and graded by consensus these images using a five-point scale [from grade 1, (best), to grade 5, (worst)], based on the sharpness of the anterior gallbladder wall, internal artifact, lesion conspicuity and acoustic shadowing from stone. Volume contrast US imaging with thin slice thicknesses (3 or 5 mm) was judged superior to both tissue harmonic imaging and with thick slice thicknesses (10 or 15 mm), with respect to the sharpness of the anterior wall and lesion conspicuity ( P<0.001). In terms of internal artifact, volume contrast imaging with thin slice thicknesses was significantly superior to both tissue harmonic imaging and volume contrast imaging with a 15 mm thickness ( P<0.001) and was judged to be marginally better than with a 10 mm thickness ( p>0.01). With regard to acoustic shadowing, volume contrast imaging with thin slice thicknesses was also significantly better than with thick slice thicknesses ( P<0.01), and it was also marginally better than tissue harmonic imaging ( P>0.01). Volume contrast US imaging with thin slice thicknesses provides a better image quality with fewer artifacts than three other types of images for the evaluation of gallbladder diseases.

Cholangiocarcinoma: pictorial essay of CT and cholangiographic findings.

Cholangiocarcinomas that involve areas from the peripheral intrahepatic duct to the distal common duct have similar morphologic features, and traditional classification schemes based on the location of the involved ducts sometimes overlap. Nevertheless, cholangiocarcinoma is usually classified as either intrahepatic or extrahepatic, and intrahepatic cholangiocarcinoma is further classified as either peripheral or hilar. However, the distinction between peripheral intrahepatic cholangiocarcinoma and hilar cholangiocarcinoma is largely based on the site of origin. Therefore, in some tumors that arise peripheral to the secondary bifurcation of one of the hepatic ducts, clear differentiation between the two types of cholangiocarcinoma is not always possible. In addition, the distinction between hilar cholangiocarcinoma and extrahepatic cholangiocarcinoma is not clearly defined. The different biologic behaviors of the tumors seem to be caused by their varying locations and their size at the time of diagnosis. Further molecular or biochemical investigation is needed to support the "field theory," which states that all cholangiocarcinomas are biologically the same tumor originating from the same biliary epithelium.