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Purpose: To analyze CT features that predict major gastrointestinal tract (GIT) complication after hepatic radiofrequency ablation (RFA)., Materials and Methods: Of 3933 patients who underwent RFA for hepatic malignancy from January 2005 to September 2016, 52 patients (1.32%) who had GIT complications were retrospectively enrolled. Electronic medical records and CT results were reviewed for location (left vs. right lobe, subcapsular vs. non-subcapsular) and tumor size, distance from the hepatic capsule, number and length of needles, ablation time, presence of artificial ascites, previous history of percutaneous treatment or operation, injured organs, length and thickness of injured GIT, presence of adjacent infiltration, ascites, mucosal discontinuity, and free air, and eccentricity. Patients were divided into those that recovered with conservative treatment (minor group) and those that required operation (major group). Chi-square test, Fisher's exact test, and Mann-Whitney U test analyzed differences between the two groups; however, the most significant variable was found using binary logistic regression analysis., Results: Of 52 patients who had GIT complications after hepatic RFA, 2 patients (0.05%) had major GIT complications, while the remaining 50 patients (1.27%) had minor complications. Most (47/52, 90.4%) of the tumors were located at subcapsular portion. 66% of tumors were located at the left hepatic lobe. Stomach was the most frequent injured organ (28/52, 53.8%), followed by colon (17/52, 32.7%) and small bowel (7/52, 13.5%). Patients with major GIT complications had significantly thicker (1.8 vs. 1.1 cm) and concentric (2/2, 100% vs. 1/50, 2.0%) bowel wall thickening with mucosal discontinuity (2/2, 100% vs. 0/50, 0%) than those with minor complications (P < 0.05)., Conclusion: GIT complication after hepatic RFA is rare and often requires conservative treatment. However, patients who show >1.65-cm-thick, concentric bowel wall thickening with mucosal disruption on CT after hepatic RFA may have major GIT injury that requires bowel surgery.

Objectives: The purpose of this study is to evaluate the diagnostic performance of HRUS, CT, and MRI for differentiating xanthogranulomatous cholecystitis (XGC) from gallbladder (GB) cancer., Materials and Methods: Patients with surgically proven XGC (n = 40) and GB cancer (n = 44), who had undergone at least one HRUS (n = 43), CT (n = 82), or MRI (n = 34) examination between 2000 and 2012, were included. Two radiologists retrospectively graded the likelihood of XGC or GB cancer using a 5-point confidence scale; they also assessed the imaging features. Statistical analyses were performed using ROC, ANOVA, and Fisher's exact test., Results: Diagnostic performance of MRI was better than HRUS for differentiating XGC from GB cancer (AUCs = 0.867 and 0.911 vs. AUCs = 0.818 and 0.86). However, HRUS showed a better performance than CT (AUCs = 0.818 and 0.86 vs. AUCs = 0.806 and 0.84) with moderate to excellent agreement (κ = 0.48-0.83). Statistically common findings for XGC included non-focal thickening, smooth GB wall, presence of intramural nodules, type I enhancement of wall, transient hepatic attenuation difference, and continuity of mucosa (p < 0.05). Co-existence of gallstones (OR = 16.5), non-focal thickening (OR = 14.7), and collapsed lumen (OR = 13.0) on HRUS, and type I enhancement on CT (OR = 3.52) were independently associated with XGC (p < 0.05)., Conclusion: Although MRI showed a better performance than both HRUS and CT, HRUS showed a better performance than CT. The co-existence of gallstones, non-focal thickening, and collapsed lumen on HRUS was independently associated with XGC.

Purpose: Registration between 2D ultrasound (US) and 3D preoperative magnetic resonance (MR) (or computed tomography, CT) images has been studied recently for US-guided intervention. However, the existing techniques have some limits, either in the registration speed or the performance. The purpose of this work is to develop a real-time and fully automatic registration system between two intermodal images of the liver, and subsequently an indirect lesion positioning/tracking algorithm based on the registration result, for image-guided interventions., Methods: The proposed position tracking system consists of three stages. In the preoperative stage, the authors acquire several 3D preoperative MR (or CT) images at different respiratory phases. Based on the transformations obtained from nonrigid registration of the acquired 3D images, they then generate a 4D preoperative image along the respiratory phase. In the intraoperative preparatory stage, they properly attach a 3D US transducer to the patient's body and fix its pose using a holding mechanism. They then acquire a couple of respiratory-controlled 3D US images. Via the rigid registration of these US images to the 3D preoperative images in the 4D image, the pose information of the fixed-pose 3D US transducer is determined with respect to the preoperative image coordinates. As feature(s) to use for the rigid registration, they may choose either internal liver vessels or the inferior vena cava. Since the latter is especially useful in patients with a diffuse liver disease, the authors newly propose using it. In the intraoperative real-time stage, they acquire 2D US images in real-time from the fixed-pose transducer. For each US image, they select candidates for its corresponding 2D preoperative slice from the 4D preoperative MR (or CT) image, based on the predetermined pose information of the transducer. The correct corresponding image is then found among those candidates via real-time 2D registration based on a gradient-based similarity measure. Finally, if needed, they obtain the position information of the liver lesion using the 3D preoperative image to which the registered 2D preoperative slice belongs., Results: The proposed method was applied to 23 clinical datasets and quantitative evaluations were conducted. With the exception of one clinical dataset that included US images of extremely low quality, 22 datasets of various liver status were successfully applied in the evaluation. Experimental results showed that the registration error between the anatomical features of US and preoperative MR images is less than 3 mm on average. The lesion tracking error was also found to be less than 5 mm at maximum., Conclusions: A new system has been proposed for real-time registration between 2D US and successive multiple 3D preoperative MR/CT images of the liver and was applied for indirect lesion tracking for image-guided intervention. The system is fully automatic and robust even with images that had low quality due to patient status. Through visual examinations and quantitative evaluations, it was verified that the proposed system can provide high lesion tracking accuracy as well as high registration accuracy, at performance levels which were acceptable for various clinical applications.

Objective: To describe the CT findings of lymphoepithelial cysts (LECs) of the pancreas and to investigate the differential findings between LECs and other pancreatic cystic lesions., Materials and Methods: Fifty-eight patients with 8 LECs (M:F = 7:1; mean age 55.1 years), 30 serous cystadenomas (SCA) (M:F = 11:19; 52.5 years), 11 mucinous cystadenomas (MCA) (M:F = 0:11; 47.2 years), and 9 pseudocysts (M:F = 6:3; 50.8 years) were included in this study. Two radiologists analyzed all CT images for 3D location, outer shape, appearance, the presence of calcification, enhancing nodule, and pancreatic duct dilatation. Size of lesions and CT number of cystic portion on precontrast CT were measured. For statistical analysis, Mann-Whitney U test and Fisher's exact test were used., Results: 75 % (6/8) of LECs showed an extrapancreatic location than all other cystic diseases in terms of 3D location (p < 0.0001). LECs showed variable outer shape without a significant difference from that of SCAs and pseudocysts (p > 0.05), but LECs showed microlobulated surface more frequently than the MCAs (p < 0.05). LECs showed a variable appearance from unilocular to multi-microcystic. CT attenuation of LECs (21.2 ± 7.1 HU) was higher than that of SCAs and MCAs (p = 0.005). Size of LECs (34.0 ± 10.8 mm) was smaller than that of MCAs (p = 0.040). There was no calcification, pancreatic duct dilatation, or enhancing nodules in LECs., Conclusion: LECs appear as a highly exophytic medium-sized cystic mass with various morphology occurring predominantly in the middle-aged or older male patients.

The registration of a three-dimensional (3D) ultrasound (US) image with a computed tomography (CT) or magnetic resonance image is beneficial in various clinical applications such as diagnosis and image-guided intervention of the liver. However, conventional methods usually require a time-consuming and inconvenient manual process for pre-alignment, and the success of this process strongly depends on the proper selection of initial transformation parameters. In this paper, we present an automatic feature-based affine registration procedure of 3D intra-operative US and pre-operative CT images of the liver. In the registration procedure, we first segment vessel lumens and the liver surface from a 3D B-mode US image. We then automatically estimate an initial registration transformation by using the proposed edge matching algorithm. The algorithm finds the most likely correspondences between the vessel centerlines of both images in a non-iterative manner based on a modified Viterbi algorithm. Finally, the registration is iteratively refined on the basis of the global affine transformation by jointly using the vessel and liver surface information. The proposed registration algorithm is validated on synthesized datasets and 20 clinical datasets, through both qualitative and quantitative evaluations. Experimental results show that automatic registration can be successfully achieved between 3D B-mode US and CT images even with a large initial misalignment.

Purpose: To retrospectively assess feasibility of dual-source dual-energy (DSDE) computed tomography (CT) for evaluation of hepatic iron accumulation in a liver phantom and liver transplantation candidates and to compare its accuracy with that of 3-T magnetic resonance (MR) imaging., Materials and Methods: This study was approved by the institutional review board; informed consent was waived. A liver agar phantom containing six tubes of iron (concentrations, 100-5000 mg of iron per 100 mL of solution) was scanned at 80 and 140 kVp with both DSDE mode and single-source dual-energy (SSDE) CT with sequential scanning mode. Difference of averaged attenuation between 80 and 140 kVp at CT (ΔH) was measured and correlated with iron concentration. Thirty-two liver transplant recipients and 55 donors who underwent DSDE CT at 80 and 140 kVp were included. Twenty-three underwent 3-T liver MR with dual-echo in-phase and opposed-phase T1-weighted and spin-echo T2-weighted imaging. Hepatic ΔH was measured at CT. On T1- and T2-weighted MR images, iron indexes were calculated. Degree of iron accumulation and macrosteatosis were determined at histologic examination (reference). Diagnostic performance of ΔH at CT and iron indexes at MR for diagnosing clinically important iron accumulation was evaluated (receiver operating characteristic [ROC] analysis)., Results: For phantom study, ΔH obtained from both DSDE mode and SSDE CT with sequential scanning mode was correlated with iron concentration (correlation coefficient, 1.00 and 0.943, respectively; P = .173). ΔH (13.53) in 10 patients with clinically important (≥ 10%) iron accumulation was significantly higher than that (7.39) in 77 patients with normal or mild iron deposition (P < .001). ΔH was significantly correlated with degree of iron accumulation (correlation coefficient, 0.430; P < .001) but not with degree of hepatic macrosteatosis (P = .216). Area under the ROC curve for diagnosing clinically important iron accumulation was 0.881 and 0.897 with CT and MR, respectively (P = .851)., Conclusion: DSDE CT is accurate for diagnosing clinically important hepatic iron accumulation without confounding influence of hepatic steatosis, with diagnostic performance on par with MR., (© RSNA, 2011.)

Objective: To prospectively evaluate the safety and short-term therapeutic efficacy of switching monopolar radiofrequency ablation (RFA) with multiple electrodes to treat medium-sized (3.1-5.0 cm), hepatocellular carcinomas (HCC)., Materials and Methods: In this prospective study, 30 patients with single medium-sized HCCs (mean, 3.5 cm; range, 3.1-4.4 cm) were enrolled. The patients were treated under ultrasonographic guidance by percutaneous switching monopolar RFA with a multichannel RF generator and two or three internally cooled electrodes. Contrast-enhanced CT scans were obtained immediately after RFA, and the diameters and volume of the ablation zones were then measured. Follow-up CT scans were performed at the first month after ablation and every three months thereafter. Technical effectiveness, local progression and remote recurrence of HCCs were determined., Results: There were no major immediate or periprocedural complications. However, there was one bile duct stricture during the follow-up period. Technical effectiveness was achieved in 29 of 30 patients (97%). The total ablation time of the procedures was 25.4 ± 8.9 minutes. The mean ablation volume was 73.8 ± 56.4 cm(3) and the minimum diameter was 4.1 ± 7.3 cm. During the follow-up period (mean, 12.5 months), local tumor progression occurred in three of 29 patients (10%) with technical effectiveness, while new HCCs were detected in six of 29 patients (21%)., Conclusion: Switching monopolar RFA with multiple electrodes in order to achieve a sufficient ablation volume is safe and efficient. This method also showed relatively successful therapeutic effectiveness on short-term follow up for the treatment of medium-sized HCCs.

Background: To assess the added value of 80 kVp images to weighted average 120 kVp images for detecting hepatocellular carcinomas (HCCs) using dual-source, dual-energy MDCT., Materials and Methods: Forty-one HCCs in 42 patients who underwent liver transplantation (LT) were included. All patients underwent quadruple-phase CT using a 64-row dual-source, dual-energy MDCT with 80 kVp and 140 kVp. For 120 kVp, a linear blending ratio of 0.3 was chosen. Interval reviews for both simulated 120 kVp images without and with pure 80 kVp data were performed independently by two radiologists. They detected HCCs using a 4-point confidence scale. Tumor-to-liver contrast-to-noise ratio (CNR) was calculated and compared between the 80 kVp and simulated 120 kVp images. The additional diagnostic value of 80 kVp images was evaluated by jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis., Results: There were 41 HCCs on pathology and 37 of the 41 HCCs were depicted on CT scan. The mean CNR of the 37 HCCs in late arterial and portal-phase images was significantly better in the 80 kVp images than in 120 kVp images. The average JAFROC figure of merit, however, was not significantly improved when 80 kVp was added. Furthermore, the number of false-positives was significantly increased in reader 1 when adding 80kVp data., Conclusion: The addition of 80 kVp CT images to simulated 120 kVp images did not significantly improve the detection of HCCs despite of the significantly better CNR of 80 kVp images., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Rationale and Objectives: The aims of this study were to compare accuracy between semiautomated and manual measurements of the longest diameter and volume of simulated hepatic tumors in phantoms and to evaluate the effects of slice thickness (ST) and reconstruction increment (RI) on accuracy., Materials and Methods: Liver phantoms with 45 hypoattenuating and 45 hyperattenuating lesions of different sizes (diameter, 13.3-50.7 mm; volume, 0.4-54.0 mm(3)) and shapes (spherical or elliptical) were scanned using a 64-row multidetector computed tomographic scanner. Images were reconstructed with ST and RI settings of 0.75 and 0.7 mm, 1.0 and 0.7 mm, 1.5 and 1.0 mm, 3.0 and 2.0 mm, 3.0 and 3.0 mm, and 5.0 and 5.0 mm. The longest diameter and volume of each lesion were measured both manually and semiautomatically. To assess accuracy, measurements were compared to reference values by calculating absolute percentage error. Comparisons of absolute percentage error between methods and between ST and RI settings were performed using paired t tests. The degree of correlation between each measurement and a reference value was also assessed., Results: The semiautomated method showed significantly higher accuracy than the manual method in volume for most ST and RI settings (0.75 and 0.7 mm, 1.0 and 0.7 mm, and 1.5 and 1.0 mm in hypoattenuating lesions and all settings in hyperattenuating lesions; P < .05) and showed similar accuracy in diameter for all ST and RI settings regardless of lesion attenuation (P > .05). Semiautomated measurements also demonstrated higher correlation with reference values than the manual method for both diameter and volume. The absolute percentage error tended to be increased as ST and RI increased for both methods, and acceptable maximum ST and RI in semiautomated method were 1.5 and 1.0 mm., Conclusions: Semiautomated computed tomographic measurement showed higher accuracy and correlation than the manual method in measuring the diameter and volume of hepatic lesions. The accuracy of both methods was highly dependent on z-axis resolution., (Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the enhancement patterns, prevalence of secondary signs, and histopathologic features of 20-mm-diameter or smaller pancreatic cancers seen on multiphasic multidetector computed tomographic (CT) images., Materials and Methods: This retrospective study was approved by the institutional review board; the requirement for informed consent was waived. From January 2002 through September 2009, the authors reviewed the clinical and imaging data of 130 consecutive patients (76 men, 54 women; mean age, 64.1 years; age range, 28-82 years) who had surgically proven 30-mm-diameter or smaller pancreatic cancers and underwent preoperative multidetector CT and 33 consecutive patients (17 men, 16 women; mean age, 65.1 years; age range, 48-84 years) who had histopathologically proven pancreatic cancer and underwent incidental multidetector CT before the diagnosis was rendered. Only pancreatic phase CT was performed in two patients, and only hepatic venous phase CT was performed in nine patients. Two radiologists in consensus classified the tumor attenuation as hyper-, iso-, or hypoattenuation during the pancreatic and hepatic venous phases. Accompanying secondary signs, temporal changes in tumor attenuation, and histopathologic findings also were analyzed. The Fisher exact test, χ(2) test, generalized estimating equation, and Student t test were used to compare the variables., Results: Seventy tumors were 20 mm or smaller, and 93 were 21-30 mm. Isoattenuating pancreatic cancers were more commonly observed among the 20-mm or smaller tumors (16 of 59, 27%) than among the 21-30-mm tumors (12 of 93, 13%) (P = .033). They were also more common among well-differentiated tumors (seven of 12, 58%) than among moderately differentiated (20 of 124, 16%) and poorly differentiated (one of 10, 10%) tumors (P = .001). The prevalence of secondary signs differed significantly according to tumor size (53 [76%] of 70 ≤20-mm tumors vs 92 [99%] of 93 21-30-mm tumors) (P < .001). The prevalence of secondary signs was high among isoattenuating pancreatic cancers (14 [88%] of 16 ≤20-mm tumors vs all 12 [100%] 21-30-mm tumors). Most of the isoattenuating tumors seen at prediagnostic CT were hypoattenuating after 6 months (100% [four of four] during pancreatic phase, 71% [five of seven] during hepatic venous phase)., Conclusion: The prevalence of isoattenuating pancreatic cancers differed significantly according to tumor size and cellular differentiation. Most small isoattenuating pancreatic cancers showed secondary signs., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101133/-/DC1., (RSNA, 2011)

Purpose: to determine the value of dual-energy (DE) scanning with virtual noncontrast (VNC) images and iodine maps in the evaluation of therapeutic response to radiofrequency ablation (RFA) for hepatic tumors., Materials and Methods: a total of 75 patients with hepatic tumors and who underwent DE computed tomography (CT) after RFA, were enrolled in this study. Our DE CT protocol included precontrast, arterial, and portal phase scans. VNC images and iodine maps were created from 80 to 140 kVp images during the arterial and portal phases. VNC images were then compared with true, noncontrast (TNC) images, and iodine maps were compared with linearly blended images, both qualitatively and quantitatively. For the former comparison, image quality and acceptability of the VNC images as a replacement for TNC images were both rated. The CT numbers of the hepatic parenchyma, ablation zone, and image noise were measured. For the latter comparison, lesion conspicuity of the ablation zone and the additional benefit of integrating the iodine map into the routine protocol, were assessed. Contrast-to-noise ratios (CNR) of the ablation zone-to-liver and aorta-to-liver as well as the CT number differences between the center and the periphery of the ablation zone were calculated., Results: The image quality of the VNC images was rated as good (mean grading score, 1.88) and the level of acceptance was 90% (68/75). The mean CT numbers of the hepatic parenchyma and ablation zone did not differ significantly between the TNC and the VNC images (P > 0.05). The lesion conspicuity of the ablation zone was rated as excellent or good in 97% of the iodine map (73/75), and the additional benefits of the iodine maps were positively rated as better to the same (mean 1.5). The CNR of the aorta-to-liver parenchyma was significantly higher on the iodine map (P = 0.002), and the CT number differences between the center and the periphery of the ablation zone were significantly lower on the iodine map (P < 0.001)., Conclusion: with DE CT scanning, VNC images can be an alternative to TNC images for evaluating the ablation zone after RFA in patients who had no a previous transcatheter arterial chemoembolization history. The iodine map improves the conspicuity of the ablation zone more than linearly blended images because of its excellent internal homogeneity and sharp ablative margin. Higher lesion-to-liver CNR on an iodine map than on standard images can be helpful for detecting residual tumors.

In order to utilize both ultrasound (US) and computed tomography (CT) images of the liver concurrently for medical applications such as diagnosis and image-guided intervention, non-rigid registration between these two types of images is an essential step, as local deformation between US and CT images exists due to the different respiratory phases involved and due to the probe pressure that occurs in US imaging. This paper introduces a voxel-based non-rigid registration algorithm between the 3D B-mode US and CT images of the liver. In the proposed algorithm, to improve the registration accuracy, we utilize the surface information of the liver and gallbladder in addition to the information of the vessels inside the liver. For an effective correlation between US and CT images, we treat those anatomical regions separately according to their characteristics in US and CT images. Based on a novel objective function using a 3D joint histogram of the intensity and gradient information, vessel-based non-rigid registration is followed by surface-based non-rigid registration in sequence, which improves the registration accuracy. The proposed algorithm is tested for ten clinical datasets and quantitative evaluations are conducted. Experimental results show that the registration error between anatomical features of US and CT images is less than 2 mm on average, even with local deformation due to different respiratory phases and probe pressure. In addition, the lesion registration error is less than 3 mm on average with a maximum of 4.5 mm that is considered acceptable for clinical applications.

Objective: The purpose of this article is to compare the T-staging accuracy and lesion detectability of MDCT with gas distention versus water distention according to the surgical and histopathologic findings, for the preoperative evaluation of gastric cancer., Materials and Methods: For a 3-month period, 113 consecutive patients (72 men and 41 women; age range, 23-85 years; mean age, 58 years) with 116 surgically confirmed gastric cancers from a single institution were included in our study. All patients had undergone preoperative MDCT with either effervescent granules taken orally (n = 55) or after having drunk 1,000 mL of tap water (n = 58) to create gastric distention. In addition to transverse images, multiplanar reformation images and 3D surface shaded display images were also obtained with gas distention CT, and multiplanar reformation images were obtained with water distention CT. The CT images were retrospectively reviewed by two abdominal radiologists separately with regard to T staging and lesion detectability. The accuracy values were compared between the two methods using Fisher's exact test., Results: The T-staging accuracy for gastric cancer did not differ significantly between gas distention and water distention CT scans, according to both radiologists (p > 0.05). Furthermore, the staging accuracy values for T1a cancers on gas distention CT scans for radiologists 1 and 2 were also comparable with those of water distention CT scans (91.1% vs 85% for radiologist 1 and 89.3% vs 85% for radiologist 2; p > 0.05). However, the tumor detection rate was significantly higher on gas distention CT scans using 2D and surface shaded display images for both radiologists (94.6% for radiologist 1 and 91.1% for radiologist 2), compared with the rates for water distention CT scans (78.3% and 73.3%) or gas distention CT scans using only 2D images (75.0% and 67.9%) (p < 0.05)., Conclusion: MDCT using the gas distention technique showed performance comparable to that of the water distention technique for the T staging of preoperative gastric cancer with better lesion detectability.

Purpose: To retrospectively assess the added value of multiplanar reformations (MPR) to axial multi-detector row computed tomographic (MDCT) images in differentiating macrocystic pancreas neoplasms., Materials and Methods: Approval from the institutional review board was obtained. Two radiologists retrospectively reviewed axial CT images of 48 pathologically proven pancreas macrocystic neoplasms with and without MPRs. They were asked to determine the presence of pancreatic duct (PD) communication with the lesions and whether the lesion is an intraductal papillary mucinous neoplasm (IPMN) or not on a 5-point confidence scale and to record the specific diagnoses and their confidence. Radiologists' performances for determining PD communication and lesion differentiation using axial CT with and without MPRs were evaluated using receiver operating characteristic analysis. To determine the accuracy of the specific diagnoses, Fisher exact and Mann-Whitney U tests were used. Interobserver agreement was also analyzed., Results: With the addition of MPRs, receiver operating characteristic analysis revealed a tendency toward improved determination of PD communication and better differentiation between IPMN and non-IPMN. However, a significant difference was found only in reviewer 2 for the determination of PD communication (P = 0.009). Diagnostic accuracy of specific diagnoses was also improved; however, the differences were not significant. Specific diagnoses were more confidently made with the addition of MPRs than with axial images alone, and a significant difference was seen for reviewer 2 (P < 0.001). Furthermore, substantial interobserver agreement was achieved with the addition of MPRs, whereas fair or substantial agreement was noted with axial images alone., Conclusions: The addition of MPRs to axial CT images may improve diagnostic performance and decrease interobserver variability of MDCT for the determination of PD communication with macrocystic pancreatic neoplasms and differentiation between IPMN and non-IPMN.

Objective: The objective of our study was to determine significant CT findings for the differentiation of biliary cystic neoplasms from simple hepatic cysts and to assess whether radiologists' performance for the differentiation is improved with the knowledge of significant CT criteria., Materials and Methods: Review of surgical and pathologic records identified 25 patients with pathologically proven biliary cystic neoplasms (biliary cystadenomas [n = 8], biliary cystadenocarcinomas [n = 4]) or simple cysts [n = 13]). Two radiologists retrospectively reviewed CT images in consensus for the location, size, and outer margin of the lesion and for the presence of an internal septum, upstream bile duct dilatation, a transient hepatic attenuation difference (THAD), calcifications, a mural nodule, three or more other cysts, and a thick septum or outer wall. Individual CT findings considered significant for the differentiation were determined using univariate statistical analyses. Then, two successive review sessions for the differentiation between the two disease entities were independently performed by two other reviewers using a 4-point confidence scale. At the first session, no information was provided to reviewers for differentiation. At the second session, however, the reviewers were told of the results of univariate analyses. Radiologists' performance was evaluated using pairwise comparison of receiver operating characteristic (ROC) curves., Results: The mean size of biliary cystic neoplasms (9.5 cm) was not significantly different from that of simple cysts (11.2 cm). The presence of upstream bile duct dilatation achieved the highest specificity (100%) for the differentiation of biliary cystic neoplasms from simple cysts, followed by THAD (84.6%), lesion location at the left lobe (76.9%), and coexistence of fewer than three other cysts (69.2%). The area under the curve of reviewers 1 and 2 significantly increased from 0.686 and 0.654 to 0.997 and 0.936, respectively, when the reviewers knew the information about the significant CT criteria (p = 0.003 and p = 0.008, respectively)., Conclusion: Upstream bile duct dilatation, lesion location at the left hepatic lobe, fewer than three coexistent cysts, and THAD were found to be highly suggestive CT findings for the differentiation of biliary cystic neoplasms from simple hepatic cysts. Radiologists' performance was significantly improved with the knowledge of these highly suggestive CT criteria.

Purpose: To analyze the imaging features of small (≤3 cm) solid pseudopapillary tumors (SPTs) seen at multiphasic multidetector computed tomography (CT) in comparison with those of larger SPTs., Materials and Methods: This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. CT images of 42 histopathologically proven SPTs in the pancreas were retrospectively reviewed. Two radiologists in consensus analyzed the CT findings for the shape, location, diameter, ratio of solid-to-cystic components, border and margin, enhancement pattern, and enhancement grade of the tumors, as well as the presence of calcification, dilatation of the pancreatic duct, and parenchymal atrophy. Then, according to the feature analysis results, the reviewers classified all SPTs as typical or atypical; they also subdivided all SPTs into small (≤3 cm) and large SPTs (>3 cm) depending on the tumor size. Differences in the morphologic features between small SPTs and large typical and atypical SPTs were statistically evaluated by using the Fisher exact test; differences in attenuation between the pre- and postcontrast images and in the dynamic enhancement pattern according to nodule size (≤3 cm versus >3 cm) were evaluated by using the χ(2) test or Fisher exact test for categorical variables., Results: There were 20 typical SPTs and 22 atypical SPTs. Of the 22 atypical SPTs, 12 (54%) were 3 cm or smaller in diameter and 10 (45%) were larger than 3 cm in diameter. Small atypical SPTs usually appeared as solid tumors with a sharp margin and without accompanying pancreatic duct dilatation or parenchymal atrophy. They also showed weak enhancement during the pancreatic phase and a gradually increasing enhancement pattern. All typical SPTs were larger than 3 cm and appeared as well-defined cystic and solid masses with heterogeneous enhancement, while all large atypical SPTs appeared as calcified solid masses or large cystic masses., Conclusion: The imaging features of small SPTs are different from those of large SPTs, and small SPTs frequently appear as purely solid tumors with a sharp margin and gradual enhancement.

Purpose: The aim of this study is to retrospectively analyze the variety of CT findings based on new pathologic classification., Materials and Methods: During a 10-year period, 59 histopathologically proven pancreatic SCTs and 13 SCTs confirmed with typical image findings and strict clinical criteria were enlisted. Two radiologists analyzed CT images for the following items in consensus: location, size, outer margin, tumor shape, the presence of mural nodule, communication with main pancreatic duct (MPD), the presence and extent of MPD dilatation, calcification, central scar, and attenuation on pre- and post-contrast CT images. In addition, typicality of CT findings was determined. A typical finding was defined as a honeycomb appearance without or with oligocystic portion. In the cases with atypical features, the type of atypical features and differential diagnosis were recorded. For the shape of the tumor, tumors were categorized into the following groups: honeycomb without or with oligocystic, pleomorphic, purely oligolocular, unilocular cystic, hypovascular solid, hypervascular solid without or with oligocystic portion, and fingerlike cystic patterns., Results: 28 SCTs (38.9%) presented a honeycomb appearance with (n=14) or without oligocystic portion (n=14) and were classified as typical cases. The remaining 44 atypical cases (61.1%) presented the following: purely oligolocular pattern in 18; hypervascular solid without (n=7) or with oligocystic portion (n=2) in 9; pleomorphic in 8; unilocular cystic in 7; and fingerlike cystic pattern in 2. Most of the lesions manifesting as hypervascular solid lesions were confused with true solid hypervascular tumors such as neuroendocrine tumors or solid pseudopapillary tumors. For most of the remaining atypical lesions, mucinous cystic neoplasm or branch duct type IPMN were included as a differential diagnosis., Conclusion: Serous cystic tumors of the pancreas can have variable CT appearances ranging from compactly solid hypervascular to clearly unilocular cystic, which reflect a varied macroscopic morphology. Only 38.9% of the SCTs show traditional typical CT features whereas a considerable proportion (61.1%) of SCTs showed atypical appearances, providing diagnostic challenges to radiologists., (Copyright 2009 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To identify the computed tomographic (CT) findings in T1a and T1b cancers and to evaluate the diagnostic performance of multidetector CT with two-dimensional multiplanar reconstruction and three-dimensional CT gastrography for evaluating the preoperative staging of gastric cancer, with special emphasis on the differentiation between T1a and T1b cancers., Materials and Methods: The institutional review board approved this retrospective study. A total of 148 patients with gastric cancer (64 T1a, 36 T1b, and 48 T2) were included. To identify CT findings in T1a and T1b cancers, two radiologists in consensus interpreted the preoperative CT images of the 100 T1 cancers to determine the morphologic characteristics to be used as staging criteria on CT images. By using univariate and multiple logistic regression analyses, the diagnostic criteria to identify T1a and T1b cancers were developed. To evaluate the diagnostic performance of multidetector CT by using the criteria, two other blinded reviewers independently analyzed the CT images of all 148 patients to assess the T (classifying the depth of invasion as T1a, T1b, or T2) and N (classifying nodal involvement as absent or present) stage. CT staging was correlated with histopathologic results. Interobserver agreement was assessed by using weighted kappa statistics., Results: The detectability of T1b cancer was significantly higher than that of T1a cancer (P = .003). T1b cancer showed well-enhancing mucosal thickening more frequently than did T1a cancer (P = .002). By using the modified CT criteria, the overall accuracy values of T staging and N staging were 64.9% (96/148) and 79.1% (117/148) for reviewer 1 and 63.5% (94/148) and 83.8% (124/148) for reviewer 2, respectively. Weighted kappa values of T and N staging were 0.795 and 0.641, respectively., Conclusion: On multidetector CT images, T1a cancer shows different imaging features than does T1b cancer regarding enhancing characteristics and detectability. Multidetector CT provides relatively valuable results of T and N staging, including differentiation between T1a, T1b, and T2 gastric cancers., (Copyright RSNA, 2010)

Objective: The purpose of this study was to retrospectively determine whether there are specific CT features that can be used to differentiate polypoid early from advanced gastric cancer and to assess the performance of radiologists using specific CT findings for differentiation., Materials and Methods: A review of medical records yielded the cases of 46 patients, 27 with polypoid early gastric cancer and 19 with polypoid advanced gastric cancer, whose CT scans were available for review. Two radiologists retrospectively reviewed the CT images for the presence and depth of dimpling at the tumor base, the presence of vessel invagination at the dimpling site, thickening of the low-attenuating outer layer, perigastric infiltration, and transmural full-thickness enhancement of the lesion. Individual CT findings relevant as predictors were determined with univariate and multivariate analyses. Individual review of CT scans subsequently was performed by two other radiologists, who were blinded to tumor stage but aware of the results of univariate and multivariate analyses. Individual performance was evaluated with receiver operating characteristic analysis., Results: The presence of severe dimpling greater than 3.5 mm at the base of the tumor (odds ratio, 31.3) had the highest odds ratio for differentiating early from advanced gastric cancer, followed by vessel invagination (odds ratio, 12.3), the presence of dimpling (odds ratio, 9.8), perigastric infiltration (odds ratio, 5.2), and transmural full-thickness enhancement (odds ratio, 4.8). Multivariate analysis showed that the presence of dimpling greater than 3.5 mm was the only independent variable that differentiated polypoid advanced gastric cancer from polypoid early gastric cancer (p = 0.001). Subsequent differentiation of advanced from early gastric cancer with the described CT findings was very good, yielding areas under the receiver operating characteristic analysis curves of 0.827 and 0.811 for the two observers., Conclusion: Greater than 3.5 mm dimpling and other ancillary CT findings are helpful in differentiating polypoid advanced gastric cancer from polypoid early gastric cancer and contribute to good individual accuracy for differentiation.

Objective: The authors undertook to investigate the diagnostic performance of high-resolution ultrasound (HRUS), and to compare the differential diagnostic and staging accuracies of endoscopic ultrasonography (EUS), HRUS, and multidetector computed tomography for gallbladder (GB) polypoid lesions and GB cancer., Summary of Background Data: Endoscopic ultrasonography was considered the most sensitive diagnostic modality for GB polypoid lesions. However, recent technical advancements in other image modalities including conventional sonography (US) allow the production of comparable images., Methods: A total of 170 patients, with a more than 1-cm sized polypoid GB lesion, and without evidence of definite local invasion to adjacent organs during primary screening, were consecutively enrolled in this prospective, blind, comparative study. After excluding 26 patients with inappropriate medical histories, 144 patients were finally enrolled. All patients underwent surgical resection. Clinical diagnoses were compared with histopathologic findings by diagnostic modality., Results: Of the 144 patients, there were 115 (79.8%) cases of benign GB polypoid lesions and 29 (20.2%) cases of GB cancers. Diagnostic sensitivities for malignancy were 90% for HRUS, 86% for EUS, and 72% for CT. When evaluating the abilities of these modalities to predict GB cancer depth of invasion, we excluded 2 unusual GB malignancies (melanoma and lymphoma), HRUS was found to have the highest diagnostic accuracy of 62.9%; EUS and CT had accuracies of 55.5% and 44.4%, respectively., Conclusions: The diagnostic accuracies of HRUS and EUS for the differential diagnosis of GB polypoid lesions were comparable. In view of patient comfort and no requirement for sedation, we consider that HRUS is likely to become an important diagnostic modality for the differential diagnosis and staging of GB polypoid lesions and early GB cancer.

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.

Purpose: To describe the computed tomographic (CT) findings of ectopic pancreas and to identify the features that differentiate it from other similarly manifesting gastric submucosal tumors such as gastrointestinal stromal tumor (GIST) and leiomyoma, which are the most common gastrointestinal submucosal tumors., Materials and Methods: This retrospective study was approved by the institutional review board and did not require informed consent. CT images of pathologically proved ectopic pancreases (n = 14), GISTs (n = 33), and leiomyomas (n = 7) in the stomach and duodenum were retrospectively reviewed. Analysis of the CT findings included evaluation of the location, contour, growth pattern, border, enhancement pattern, and enhancement grade of the tumor, as well as the presence of surface dimpling, prominent enhancement of overlying mucosa, and low intralesional attenuation. The attenuation of each lesion, the long diameter (LD), the short diameter (SD), and the LD/SD ratio were measured. Among these findings, statistically significant variables were determined by using the chi(2) test (to compare the categoric variables), the Student t test (for quantitative analysis), and the receiver operating characteristic curve (to determine the optimal cutoff of the LD/SD ratio)., Results: The typical location (prepyloric antrum and duodenum), endoluminal growth pattern, ill-defined border, prominent enhancement of overlying mucosa, and an LD/SD ratio of greater than 1.4 were found to be significant for differentiating ectopic pancreas from other tumors (P < .05 for each finding). When at least two of these five criteria were used in combination, the sensitivity and specificity for diagnosing ectopic pancreas were 100% (14 of 14) and 82.5% (33 of 40), respectively. When four of these criteria were used, a sensitivity of 42.9% and a specificity of 100% were achieved., Conclusion: By using specific CT criteria, ectopic pancreas can be differentiated from small GIST or leiomyoma with a high degree of accuracy., ((c) RSNA, 2009.)

Purpose: To retrospectively evaluate the diagnostic performance of multidetector row CT (MDCT), superparamagnetic iron oxide (SPIO)-enhanced MRI (S-MRI), and dual-contrast MRI (DC-MRI) in predicting the appropriateness of recipients with hepatocellular carcinoma (HCC) for liver transplantation (LT), based on Milan criteria., Materials and Methods: This retrospective study received Institutional Review Board approval. Requirement for patient informed consent was waived. During a 3-year period, 80 patients who underwent LT were enrolled in this study. However, 2 patients in whom >10 HCCs were present were excluded from the analysis of detection performance of imaging modalities for HCC. MDCT and DC-MRI examinations with the sequential use of SPIO and gadolinium were performed in all patients. Interval readings for MDCT, S-MRI, and DC-MRI were performed. Two radiologists independently recorded confidence levels using a 4- and 5-point scale for the presence of HCC and for the appropriateness regarding LT, respectively. Image interpretation was compared with histopathological results on a lesion-by-lesion basis. Diagnostic performance of the 3 imaging techniques was compared using jackknife alternative free-response receiver operating characteristic and ROC analyses., Results: Eighty-two HCCs were detected in 38 of 78 patients. Twenty-seven HCCs were larger than 2 cm in diameter and 55 HCCs were smaller than 2 cm in diameter. Among 80 patients included for the assessment of eligibility for LT, 69 recipients were categorized as appropriate and the remaining 11 patients were found to be inappropriate for LT based on Milan criteria. In terms of detecting HCCs, the reader-averaged figure of merit was highest for DC-MRI (0.764), followed by S-MRI (0.702) and MDCT (0.672). The use of DC-MRI was significantly better than the use of the other 2 modalities specifically for HCCs smaller than 2 cm in diameter (P < 0.001) although not for those larger than or equal to 2 cm (P = 0.125-1). The AZ value for predicting the appropriateness for LT was highest with the use of S-MRI (0.841), followed by the use of DC-MRI (0.830) and the use of MDCT (0.790). However, significant differences were not seen for the predictions determined by both radiologists (P = 0.384-1). This result might be because of the small number of patients who had a critical number of HCCs (ie, 2 approximately 4 HCCs)., Conclusion: DC-MRI showed significantly better diagnostic performance in transplantation candidates for the detection of HCCs, particularly small HCCs, than both MDCT and S-MRI. However, for assessing the appropriateness of a transplantation recipient based on Milan criteria, MDCT, S-MRI, and DC-MRI showed comparable diagnostic accuracy without a statistical difference.

Background: To retrospectively analyze computed tomography (CT) features of adenosquamous carcinoma (ASC) of the extrahepatic bile duct and to correlate them with pathologic findings., Methods: Six patients who underwent radical surgical resection for ASC of extrahepatic bile duct were included. CT and pathologic findings were analyzed and correlated with each other., Results: Five ASCs were periductal infiltrative type and the remaining one was intraductal polypoid type. Histologically, ASC was composed of squamous and glandular components which mixed in an intermingled pattern and was characterized by a high local aggressiveness mainly due to the squamous component. The most common CT findings were a segmental wall thickening with delayed enhancement. Overall, CT features were well correlated with pathologic findings. However, CT tended to underestimate radial extent of the tumor compared with histologic findings., Conclusions: Histopathologically, ASC of the extrahepatic bile duct is characterized by greater local aggressiveness. However, their CT findings are not quite different from those of usual adenocarcinoma due to the unique geographic characteristic of being located at a very limited space.

Purpose: To investigate the diagnostic value of quantitative determination and three-dimensional color mapping of the arterial enhancement fraction (AEF) of the liver for the detection of hepatocellular carcinoma (HCC)., Materials and Methods: This retrospective study was approved by the institutional review board; informed consent was waived. Eighty-two patients (mean age, 56.2 years +/- 10.7 [standard deviation]), 69 men (mean age, 57.1 years +/- 10.0) and 13 women (mean age, 51.6 years +/- 13.6), were followed-up for HCC or liver cirrhosis by using available multiphasic multidetector computed tomographic (CT) scans. Quantitative AEF color maps (the ratio of the attenuation increment during the arterial phase to the attenuation increment during the portal venous phase) of the whole liver were created from routine CT images by using prototypic software. Three radiologists independently analyzed a multiphasic CT image set; 4 weeks later, to avoid any potential recall bias, they independently analyzed a combined image set of the quantitative color maps and the multiphasic CT images. The additional diagnostic value of the color mapping was evaluated by means of jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis., Results: The mean AEF of HCCs (75.6 +/- 13.3) was significantly higher than that of liver parenchyma (23.4 +/- 8.2) (P < .001). The average JAFROC figure of merit was 0.861 on the initial multiphasic CT image set. This increased to 0.933 on the second session with the combined image set (P < .05). The mean sensitivity for HCC detection increased from 71.7% with the multiphasic CT image set to 88.8% with the combined image set., Conclusion: Quantitative color mapping of the AEF can increase the sensitivity and diagnostic performance of multiphasic multidetector CT for detecting HCC. Supplementamaterial:http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC1http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC2http://radiology.rsnajnls.org/cgi/content/full/250/2/425/DC3

Objective: The purpose of this article is to describe the roles of sonography, MDCT, MRI, and direct cholangiography in the evaluation of hilar cholangiocarcinoma., Conclusion: Hilar cholangiocarcinoma is a primary malignant tumor typically located at the confluence of the right and left ducts within the porta hepatis. Staging of hilar cholangiocarcinoma with various imaging techniques is crucial for management, and a comprehensive approach is needed for accurate preoperative assessment.

Objective: The objective of our study was to determine the diagnostic value of analyzing the pattern of gallbladder wall enhancement on MDCT to characterize diffuse gallbladder wall thickening as benign or malignant., Materials and Methods: MDCT scans obtained during the portal venous phase in 78 patients with gallbladder wall thickening caused by various pathologic conditions were retrospectively reviewed by two blinded observers. The CT features of benign and malignant gallbladder wall thickening were compared by means of univariate and multivariate analyses. The study cases were then divided into five patterns according to enhancement pattern. Using these five patterns, two radiologists reviewed the MDCT images and recorded their diagnostic confidence for differentiating benign versus malignant cause on a 5-point scale. The diagnostic performance of CT was evaluated by each observer using a receiver operating characteristic curve analysis., Results: The thicknesses of the inner and outer layers ("thick" enhancing inner layer > or = 2.6 mm, "thin" outer layer < or = 3.4 mm), strong enhancement of the inner wall, and irregular contour of the affected wall were significant predictors for a malignant cause of gallbladder wall thickening (p < 0.001). The two-layer pattern with a strongly enhancing thick inner layer and weakly enhancing or nonenhancing outer layer and the one-layer pattern with a heterogeneously enhancing thick layer were patterns that were significantly associated with gallbladder cancer (p < 0.05). When we consider those two enhancing patterns as a sign of malignancy, the diagnostic accuracy of MDCT was 89.1% and 87.6% for the two observers, respectively., Conclusion: Analyzing the enhancement pattern of a thickened gallbladder wall on MDCT is helpful in differentiating gallbladder cancer from benign inflammatory diseases.

The aim of this study was to compare the diagnostic performance of multidetector row helical CT (MDCT) and gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging (in the detection and characterization of focal liver lesions. Two blind reviewers analyzed the MDCT and MR images of a total of 44 malignant and 85 benign lesions in 46 patients independently. Receiver operating characteristic curves were established to analyze the results for each reviewer and modality.

Background: To determine whether CT gastrography can be used as a comprehensive imaging modality for the evaluation of gastrointestinal stromal tumor (GIST) of the stomach., Methods: Thirty patients with gastric GISTs were included. Using CT gastrography, two radiologists determined the morphology, location, size of the tumor, and the nearest distance from the tumor to the gastroesophageal junction or pylorus in consensus. The ability of 3D CT gastrography in dealing with surface-shaded/transparent images and virtual endoscopic images was also evaluated and compared with the results of barium study and gastroscopy, respectively., Results: In regard to lesion morphology and location, almost perfect agreements (kappa = 0.87 approximately 1.00) were achieved between CT gastrography and surgery, and the difference in lesion size between CT and surgery was not statistically significant (P = 0.824). In terms of the distance from the tumor to the gastroesophageal junction or pylorus, a statistically significant difference was found between the laparoscopic and open gastric surgery groups (P < 0.001). Findings on CT gastrography were mostly similar or superior to those seen on barium study and gastroscopy., Conclusions: CT gastrography can serve as a comprehensive imaging test for the preoperative evaluation of gastric GIST.

Objective: To assess the diagnostic value of arterial, pancreatic, and hepatic phase imaging with multidetector-row computed tomography of a bile duct malignancy., Methods: Our institutional review board approved this retrospective study and waived the requirement for informed consent. Forty-two patients with surgically proven hilar or extrahepatic cholangiocarcinoma, who underwent preoperative imaging with triple-phasic multidetector-row computed tomography, were included in this study. Images obtained during each phase were reviewed by 2 independent observers who assessed the tumor conspicuity and the biliary extent of the tumor and vascular invasion by the tumor. For quantitative analysis, another radiologist measured the tumor attenuation, the normal liver parenchyma, the aorta, and the main portal vein on each phase image., Results: The degree of tumor conspicuity was higher in the pancreatic and hepatic phases than in the arterial phase (P < 0.01); however, there was no statistical difference in tumor conspicuity between the pancreatic and hepatic phases (P > 0.05). The mean tumor attenuation was greater in the hepatic phase at 114.2 +/- 24.6 Hounsfield units versus 72.9 +/- 18.3 Hounsfield units in the arterial phase (P < 0.001). The images obtained in the hepatic phases were significantly superior to those obtained in the arterial phase for predicting the tumor involvement into the secondary biliary confluence (P < 0.05). In predicting for the vascular involvement by the tumors, there was no significant difference among the 3 enhancement phases (P > 0.05)., Conclusions: Routine acquisition of arterial phase images is not necessary for successful detection and evaluation of the extent of hilar or extrahepatic bile duct carcinoma.

Liver transplantation has been considered to be the only causal treatment for liver cirrhosis patients with hepatocellular carcinoma (HCC) due to its theoretical advantage of eliminating both the tumor and liver disease. However, because of the shortage of donor organs, it is strongly recommended that liver transplantations should be performed on cirrhotic patients with HCCs only when the patients meet the predetermined criteria in terms of number and extent of HCCs. Imaging is thus decisive in the patient inclusion or exclusion from transplantation lists. The imaging techniques used are CT, MRI and ultrasonography. The latter has been proven to be ineffective for HCC surveillance in transplant recipients because of its heavy operator dependence and unreliable detection of small and intermediately sized HCCs. The purpose of this article, then, is to systematically review the diagnostic performances of single-/multidetector row CT, dynamic gadolinium-enhanced MRI, superparamagnetic iron oxide (SPIO)-enhanced MRI and double-contrast MRI using both gadolinium and SPIO for the detection of HCCs with special emphasis on liver transplantation., (Copyright 2008 S. Karger AG, Basel.)

To retrospectively assess the value of multiplanar reformations (MPRs) compared with standard axial images in the assessment of hilar and extrahepatic bile duct cancer. Forty-eight patients with confirmed bile duct cancer were included as preoperative work-ups; all of these patients underwent contrast-enhanced multidetector CT consisting of axial and MPR images. Two radiologists independently assessed the axial images alone and the combined axial and MPR images in the coronal and sagittal planes for the presence of tumor, its extent, vascular involvement, and resectability. The results were compared with surgical and pathologic findings. For tumor presence and conspicuity, combined axial and MPR images had higher values than the axial only images. For evaluation of tumoral extent, there was no difference between the two image sets for either reader. The accuracy for tumor extent was lower in hilar cancer than in extrahepatic bile duct cancer. For evaluation of vascular involvement and resectability, the area under the receiver operating characteristic curve of axial images was not significantly different from that of the reformatted images. The addition of MPR images to the standard axial images did not significantly improve the diagnostic performance of MDCT in the evaluation of the bile duct cancer.

Purpose: To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses., Materials and Methods: A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis., Results: The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI., Conclusion: Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas., (Copyright 2007 Wiley-Liss, Inc.)

Background: In this study, we evaluated the CT findings of patients with hepatoid adenocarcinoma of the stomach., Methods: The CT scans of eight patients (seven males and one female; age range 44-70 years; mean age 59 years) with histologically proven hepatoid adenocarcinoma of the stomach were retrospectively evaluated by two radiologists in consensus. Scans were evaluated for gastric wall thickening, involved site enhancement, adjacent organ invasion, lymphadenopathy, distant metastases, and venous tumor thrombosis., Results: Tumors appeared as eccentric wall thickening (n = 8) and heterogeneous enhancement (n = 7). Adjacent organ invasions were noted to liver (n = 3), pancreas (n = 2), and esophagus (n = 1). All eight patients had a regional lymphadenopathy larger than 8 mm in its short axis. Distant metastases (liver, n = 4; non-regional lymph node, n = 1) were also noted. Venous tumor thrombosis was identified in the portal vein (n = 3), splenic vein (n = 1), main portal vein (n = 1), or right gastroepiploic vein (n = 1) in the regions near primary gastric tumors or metastatic masses., Conclusion: On CT scans, hepatoid adenocarcinoma of the stomach appears as an eccentric gastric wall thickening and shows a strong tendency for liver and lymph node metastasis and venous invasion around the primary gastric tumor or a metastatic hepatic mass.

Purpose: To evaluate the use of multidetector computed tomographic (CT) esophagography to grade esophageal varices and differentiate between varices at low risk and those at high risk for bleeding, with endoscopy as the reference standard., Materials and Methods: This study was approved by the institutional review board; all subjects gave informed consent. Ninety patients with cirrhosis (65 men, 25 women; mean age, 54.8 years; range, 21-77 years) were prospectively enrolled and underwent endoscopy and CT esophagography. Esophageal varices were graded independently at endoscopy by two endoscopists. CT esophagograms were interpreted retrospectively with a four-point scale by two radiologists blinded to other findings. Interobserver agreement between each radiologist and endoscopist was determined; endoscopic and CT esophagographic grades of esophageal varices were correlated. Radiologist performance for differentiation between low- and high-risk varices for bleeding on the basis of morphology at endoscopy was evaluated with receiver operating characteristic analysis. Patients were interviewed to determine acceptance at both examinations., Results: Thirty-seven of 90 patients had grade 0, 23 had grade 1, 18 had grade 2, and 12 had grade 3 esophageal varices. Thus, 60 patients were determined to be in a low-risk group and 30 in a high-risk group for variceal bleeding at endoscopy. There was almost perfect agreement in grading esophageal varices between endoscopists. There was close correlation (P < .001) and substantial agreement between endoscopic and CT esophagographic grades. Radiologist performance for differentiating between low- and high-risk varices was 0.931-0.958 (area under receiver operating characteristic curve). Patient interview results revealed that CT esophagography had better acceptance than did endoscopy (P < .001)., Conclusion: Use of CT esophagography allows grading of esophageal varices and differentiation between low- and high-risk varices and shows better patient acceptance than does endoscopy., ((c) RSNA, 2007.)

Objective: To determine whether the computed tomographic (CT) findings of primary and recurrent combined hepatocellular-cholangiocarcinoma (HCC-CC) can predict the main tumor component on histopathologic examination, and to describe the recurrence patterns of HCC-CC after surgery., Methods: Preoperative and postoperative CT findings of 12 HCC-CC patients who underwent curative surgery were retrospectively reviewed. The main features of the primary and recurrent tumors on CT and the pathological findings were classified as hepatocellular carcinoma (HCC)-dominant and cholangiocarcinoma (CC)-dominant groups. The concordance between the preoperative CT features and the initial pathological findings was evaluated using kappa statistics. The survival periods of the HCC-dominant and the CC-dominant group were compared using the Mann-Whitney U test., Results: In 11 (91.7%) of 12 patients, the main CT features of HCC-CC were in strong agreement with main pathological findings (kappa = 0.824). The most common site of recurrence was the remnant liver. In 3 cases, only nodal metastasis was noted. The mean survival period was significantly longer in the HCC-dominant group than in the CC-dominant group of recurrent tumor (P = 0.016)., Conclusions: Contrast-enhanced CT scanning can predict the dominant component of primary and recurrent HCC-CC. This capability can optimize treatment strategy for the patient with recurrent HCC-CC.

The aim of this study was to determine whether multidetector computed tomography (MDCT) imaging, including CT esophagography (CTE), can be used as a comprehensive imaging test for esophageal tumors. Twenty-three patients with esophageal neoplasms underwent MDCT with esophageal distension and endoscopy. Of them, 20 underwent barium study. Two radiologists independently reviewed MDCT images with 3D CT esophagography (CTE) including CT endoscopy and were asked to determine the presence of the esophageal lesions and characterize them using a five-point confidence scale. The radiologists' performance for the lesion detection and characterization was evaluated by receiver operating characteristic (ROC) analysis. They were also requested to determine the local staging of esophageal cancer, and the overall accuracies of MDCT for local staging were calculated. The ability of MDCT with CTE was also evaluated compared with conventional studies. CTE images successfully revealed 14 of 16 esophageal cancers and all seven submucosal tumors. Two esophageal cancers, both confined to the mucosal layer, were undetected. The Az values of the MDCT images were 0.954-0.957 for determining the presence of a lesion and 0.954-0.995 for differentiating between cancer and submucosal tumors. The overall accuracies for T and N staging were 42.9% and 85.7%, respectively. In 80% and 74% of cases, CTE gave similar or superior information to barium study and endoscopy, respectively. MDCT esophagography has the potential to serve as a comprehensive imaging modality for evaluating esophageal tumors as it provides accurate information regarding the detection and characterization of esophageal tumors as well as the similar information to conventional studies.

Purpose: To compare the diagnostic performance of CT angiography (CTA) and MR angiography (MRA) for preoperative hepatic vascular evaluation in living liver donors., Materials and Methods: Twenty-eight living donor candidates underwent preoperative CTA and MRA. Two blinded radiologists evaluated the anatomic types of the hepatic artery (HA) and portal vein (PV), and the number of aberrant hepatic veins (HVs) on both CTA and MRA, independently. Four grades of confidence levels were used to indicate the clarity of depiction of the HA and PV. Surgical findings were used as a standard of reference., Results: For determining the anatomic types of the HA and PV, and the number of aberrant HVs, CTA and MRA did not significantly differ in terms of accuracy ([89%, 96%, and 68% on CTA] vs. [86%, 93%, and 68% on MRA] for reader 1, P>0.05; and [93%, 100%, and 86% on CTA] vs. [89%, 93%, and 79% on MRA] for reader 2, P>0.05). Confidence for the depiction of major branches of HA and PV did not differ between CTA and MRA, except for a better depiction of the left HA (LHA) on CTA (P<0.05), Conclusion: In living donor candidates, both CTA and MRA can provide a complete evaluation of the hepatic vascular anatomy., (Copyright (c) 2006 Wiley-Liss, Inc.)

Objective: To determine the CT features capable of differentiating hepatocellular carcinoma (HCC) with bile duct tumor invasion (BDTI) from intraductal cholangiocarcinoma (IDCC)., Methods: Multiphasic CT images of 14 patients with HCC with BDTI and 18 patients with IDCC were retrospectively reviewed. Analysis of the CT findings included the size, location, and margin of the intraductal mass, the enhancement pattern of intraductal lesions, degree of ductal dilatation, presence of downstream ductal dilatation and ductal wall thickening, presence of parenchymal mass and its size, continuity of parenchymal mass with intraductal mass, and liver cirrhosis. Objective evaluation of the enhancement patterns of intraductal tumors was done by measuring the CT attenuation coefficients of the tumors and the uninvolved hepatic parenchyma in each phase. Among these findings, statistically significant variables were then determined using Fisher exact test or Mann-Whitney test., Results: Significant variables that helped differentiating HCC with BDTI from IDCC included the presence of parenchymal mass, liver cirrhosis, and the hyperattenuating intraductal tumor on the hepatic arterial phase (HAP). On unenhanced images, the tumor-to-liver contrast of IDCC (16.7 +/- 8.1) was greater than that of HCC with BDTI (6.4 +/- 10.4), but on HAP, that of HCC with BDTI (26.5 +/- 28.2) was greater than that of IDCC (5.9 +/- 18.7) (P < 0.05). In addition, there was a significant difference in the enhancement ratio of the intraductal tumors on portal venous phase (PVP) between the 2 conditions (P = 0.003)., Conclusions: Several objective and subjective multiphasic CT findings may help differentiating HCC with BDTI from IDCC.

Objective: To determine the computed tomography (CT) features capable of differentiating hepatocellular carcinoma (HCC) with bile duct tumor invasion (BDTI) from intraductal cholangiocarcinoma (IDCC)., Methods: Multiphasic CT images of 14 patients with HCC with BDTI and 18 patients with IDCC were retrospectively reviewed. Analysis of the CT findings included the size, location, and margin of the intraductal mass; enhancement pattern of intraductal lesions; degree of ductal dilatation; presence of downstream ductal dilatation and ductal wall thickening; presence of a parenchymal mass and its size; continuity of the parenchymal mass with the intraductal mass; and liver cirrhosis. Objective evaluation of the enhancement patterns of intraductal tumors was done by measuring the CT attenuation coefficients of the tumors and the uninvolved hepatic parenchyma in each phase. Among these findings, statistically significant variables were then determined using the Fisher's exact test or Mann-Whitney U test., Results: Significant variables that helped to differentiate HCC with BDTI from IDCC included the presence of a parenchymal mass, liver cirrhosis, and a hyperattenuating intraductal tumor on the hepatic arterial phase (HAP). On unenhanced images, the tumor-to-liver contrast of IDCC (16.7+/-8.1) was greater than that of HCC with BDTI (6.4+/-10.4), but on the HAP, that of HCC with BDTI (26.5+/-28.2) was greater than that of IDCC (5.9+/-18.7) (P<0.05). In addition, there was a significant difference in the enhancement ratio of the intraductal tumors on the portal venous phase between the 2 conditions (P=0.003)., Conclusions: Several objective and subjective multiphasic CT findings may help to differentiate HCC with BDTI from IDCC.

Objective: We hypothesized that performing CT gastrography with the patient in the left posterior oblique (LPO) position would provide better distention and less residual fluid for the lower part of the stomach than CT gastrography with the patient in the standard supine position., Conclusion: The LPO position for CT guaranteed the distensibility of and minimal residual fluid in the lower part of the stomach, thus resulting in excellent 3D CT gastrographic images.

Objective: The purpose of this study was to identify predictors of malignancy on CT for the evaluation of gastrointestinal stromal tumors of the stomach., Materials and Methods: The medical records at our institution of 81 patients with a histologic diagnosis of gastrointestinal stromal tumor of the stomach were reviewed. Two radiologists retrospectively reviewed the CT findings by consensus with respect to lesion size, contour, tumor growth pattern, enhancing pattern, degree of enhancement, mesenteric fat infiltration, ulceration, calcification, lymphadenopathy, direct invasion to adjacent organ, and distant metastasis. Categoric variables were compared using the chi-square or Fisher's exact test. Multiple stepwise logistic regression analysis by means of forward selection was performed to determine significant predictors of high mitotic rate. Univariate analysis and multivariate analysis were also performed in a subgroup of 36 tumors with maximal diameter of 5 cm or smaller., Results: Size, presence of an ulcer, mesenteric fat infiltration, direct organ invasion, and metastasis were more frequently observed during univariate analysis in tumors with a high mitotic rate (p < 0.05). With stepwise logistic regression analysis, the size (odds ratio, 2.57; 95% CI; 1.42-4.67) was the only significant predictor of a high mitotic rate. In a subgroup of 36 tumors 5 cm or smaller, differentiation of benign from malignant tumors was not possible using CT., Conclusion: Although presence of an ulcer, mesenteric fat infiltration, direct organ invasion, and metastasis were more frequently observed in tumors with a high mitotic rate, no CT feature, other than size, was found to have predictive value with respect to malignant gastrointestinal stromal tumors of the stomach.

Purpose: We investigated the quality and usefulness of spiral computed tomography and three-dimensional reconstruction in children with obstruction of the central airways as a complication of congenital heart disease., Materials and Methods: Spiral computed tomography with three-dimensional reconstruction was performed in 49 children with obstruction of the central airways seen as a complication of congenital heart disease. Spiral scanning was performed during breathing in 40, and after sedation with chloral hydrate in 38. Contrast medium was administered through a pedal venous route in 42. We analyzed the motion artifact, additional information provided by, and clinical usefulness, of the three-dimensional images. We also investigated the factors influencing the quality of the images., Results: Stenoses were seen in the trachea in 21 patients, and in bronchuses in 28. Their causes were an anomaly of the aortic arch in 6, posterior displacement of the aortic arch in 7, posterior displacement of the ascending aorta in 5, compression of the brachiocephalic artery in 5, absent pulmonary valve syndrome in 6, displaced or dilated cardiovascular structure in 17, and pulmonary arterial sling in 2. Motion artifact caused mild or negligible degradation of images in all patients except 6. Breath-holding in non-sedated children produced more severe motion artifact than did cardiovascular pulsation. Three-dimensional images provided additional information over two-dimensional images in 11, and provided clinically useful information in 10. Contrast injection via the pedal route was better for the quality of three-dimensional images than brachiocephalic injection (p = 0.013)., Conclusions: Three-dimensional computed tomography is useful in evaluation of obstruction of the central airways in children with congenital heart disease. Despite the fact that motion artifact is unavoidable, the quality of three-dimensional images is acceptable for making a proper and accurate diagnosis. A pedal route is recommended for injection of contrast medium.