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Objective: The purposes of this study were to assess the widths of the intercostal spaces of the right inferior human rib cage through which high-intensity focused ultrasound therapy would be applied for treating liver cancer and to elucidate the demographic factors associated with intercostal space width., Subjects and Methods: From March 2013 to June 2013, the widths of the intercostal spaces and the ribs at six areas of the right inferior rib cage (area 1, lowest intercostal space on anterior axillary line and the adjacent upper rib; area 2, second-lowest intercostal space on anterior axillary line and the adjacent upper rib; areas 3 and 4, lowest and second-lowest spaces on midaxillary line; areas 5 and 6, lowest and second-lowest spaces on posterior axillary line) were sonographically measured in 466 patients (214 men, 252 women; mean age, 53.0 years) after an abdominal sonographic examination. Demographic factors and the presence or absence of chronic liver disease were evaluated by multivariate analysis to investigate which factors influence intercostal width., Results: The width of the intercostal space was 19.7 ± 3.7 mm (range, 9-33 mm) at area 1, 18.3 ± 3.4 mm (range, 9-33 mm) at area 2, 17.4 ± 4.0 mm (range, 7-33 mm) at area 3, 15.4 ± 3.5 mm (range, 5-26 mm) at area 4, 17.2 ± 3.7 mm (range, 7-28 mm) at area 5, and 14.5 ± 3.6 mm (range, 4-26 mm) at area 6. The corresponding widths of the ribs were 15.2 ± 2.3 mm (range, 8-22 mm), 14.5 ± 2.3 mm (range, 9-22 mm), 13.2 ± 2.0 mm (range, 9-20), 14.3 ± 2.2 mm (range, 9-20 mm), 15.0 ± 2.2 mm (range, 10-22 mm), and 15.1 ± 2.3 mm (range, 8-21 mm). Only female sex was significantly associated with the narrower intercostal width at areas 1, 2, 3, and 5 (regression coefficient, 1.124-1.885; p = 0.01-0.04)., Conclusion: There was substantial variation in the widths of the intercostal spaces of the right inferior rib cage such that the anterior and inferior aspects of the intercostal space were relatively wider. Women had significantly narrower intercostal spaces than men.

Objective: The objective of our study was to determine the prevalence of thickening and signal alteration of the distal semimembranosus (SM) tendon on knee MRI and analyze the patient factors associated with abnormal MR findings of the distal SM tendon., Materials and Methods: Knee MRI scans of 116 subjects (58 men, 58 women; mean age, 48.5 years; range, 18-79 years) who underwent knee surgery were evaluated to assess the distal SM tendons in terms of signal alteration and thickness. To determine the factors associated with MR findings of the distal SM tendon, we assessed demographic characteristics; Kellgren-Lawrence radiographic osteoarthritis grading; history of trauma; the condition of the cruciate ligaments, collateral ligaments, and menisci; and whether there were cystic lesions around the SM tendon. In addition, 55 control subjects with normal knee MRI findings based on the electronic MRI patient database who had anterior knee pain and did not undergo surgery were enrolled., Results: Abnormal thickening of the distal SM tendon was found in 52.6% of knees and signal alteration in 44.8%. Univariate analysis revealed significant associations between abnormal thickening and age, body mass index, history of trauma, osteoarthritis, medial collateral ligament (MCL) thickening, and anterior cruciate ligament (ACL) tear. As for signal alteration, univariate analysis showed that age, body mass index, osteoarthritis, and MCL thickening were statistically significant factors. Multivariate binary logistic regression analyses showed that osteoarthritis and MCL thickening were the strong independent predictors in thickening and signal alteration of the distal SM tendon., Conclusion: Signal alteration and abnormal thickening of the distal SM tendon on MRI are frequently seen in daily practice. These MR findings are strongly associated with osteoarthritis and MCL thickening.

Objective: MRI-guided high-intensity focused ultrasound (HIFU) ablation is increasingly adopted for treating symptomatic uterine fibroids. As a noninvasive therapy performed on an outpatient basis, it has been viewed by patients to have distinct advantages over other treatment options. However, its breadth of clinical application is still limited. To address this issue, various techniques have been implemented., Conclusion: In this article, we discuss techniques that contribute to widening patient selection for MRI-guided HIFU therapy of uterine fibroids.

Objective: The objective of our study was to assess whether fusion imaging of conventional ultrasound and liver CT or MR images can improve the conspicuity of lesions and feasibility of percutaneous radiofrequency ablation (RFA) for the treatment of hepatocellular carcinomas (HCCs) not visible on ultrasound. Whether peritumoral anatomic landmarks can be used for the placement of an electrode in HCCs not visible on ultrasound even after image fusion was also evaluated., Materials and Methods: Planning ultrasound for percutaneous RFA was performed using conventional ultrasound first and then using fusion imaging later during the same session. The visibility of HCCs and feasibility of RFA on conventional ultrasound and on fusion imaging were assessed. We evaluated how many HCCs initially not visible on conventional ultrasound could be visualized and ablated after applying the fusion imaging technique. One hundred twenty HCCs not visible on conventional ultrasound in 96 patients were included., Results: When fusion imaging was applied, 38 of the 120 (31.7%) HCCs that were initially not visible could be seen and RFA was feasible. Among the remaining 82 HCCs still not visible after image fusion, 26 (31.7%) were ablated under the guidance of fusion imaging the technique based on peritumoral anatomic landmarks. Overall, 64 of 120 (53.3%) HCCs (59.4%, 57 of 96 patients) not visible on conventional ultrasound could be ablated under the guidance of the fusion imaging technique., Conclusion: Fusion imaging can improve the conspicuity of HCCs and the feasibility of percutaneous RFA of HCCs not visible on conventional ultrasound. Peritumoral anatomic landmarks can be used for electrode placement in HCCs that are still not visible even after image fusion.

Objective: In MRI-guided high-intensity focused ultrasound ablation of uterine fibroids, bowel interposition in the sonication path is often problematic. The purpose of this article is to discuss a bowel-manipulation technique to displace the bowel loop, which consisted of sequential applications of urinary bladder filling, rectal filling, and urinary bladder emptying., Conclusion: This technique contributed to a decreased screening failure rate and succeeded in consistently displacing the bowel loop, thus allowing safe treatment of fibroids in the anteverted or anteflexed uterus.

Objective: The purpose of this study was to determine whether fusion imaging-guided percutaneous radiofrequency ablation (RFA) is effective in the management of hepatocellular carcinoma (HCC) that has poor conspicuity at conventional sonography., Subjects and Methods: Percutaneous RFA of HCC with poor conspicuity was performed under fusion imaging guidance. The time needed for image fusion between the ultrasound and CT or MR images was recorded. The quality of image fusion and the degree of operator confidence in identifying the index tumor were graded on 4-point scales. Technical success and procedure-related complications were evaluated with liver CT immediately after RFA., Results: Thirty patients with HCC (1.0 ± 0.3 cm) were enrolled. Twenty-seven of the 30 lesions detected at planning ultrasound were identified with fusion imaging. Of the 30 HCC candidate lesions detected with ultrasound, five were found to be pseudolesions close to the index tumor. The time needed for image fusion for the 27 lesions was 3.7 ± 2.1 minutes (range, 1.3-9.0 minutes). The quality of image fusion was graded 3.4 ± 0.6, and the degree of operator confidence in identifying the 30 HCCs, 3.3 ± 0.9. The technical success rate was 90% (27/30) in intention-to-treat analysis and 100% in analysis of actually treated lesions. There were no major RFA-related complications., Conclusion: Fusion imaging-guided percutaneous RFA is effective in the management of HCC that has poor ultrasound conspicuity.

Objective: This study was designed to evaluate the frequency, morphological patterns, sequential changes, and clinical significance of venous thrombosis after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC)., Materials and Methods: A total of 1379 RFAs performed in 1046 patients with HCC (mean tumor size, 1.93 cm) were surveyed. We retrospectively reviewed all radiologic reports before and after RFA and selected 15 patients with newly developed procedure-related venous thrombosis. Procedure-related thrombosis was defined as being adjacent to the ablation zone and developing within 4 months after the procedure. We evaluated the frequency, morphological patterns, sequential changes, and clinical course of venous thrombosis (mean follow-up, 662.9 days). Four cases with local tumor progression were identified among the 15 patients, and their clinical implications were evaluated., Results: A total of 15 venous thromboses (1.08%; 12 portal and three hepatic veins) developed after RFA (range, 0-128 days; mean, 37 days). The thromboses were found in central (n = 10), peripheral (n = 4), and both central and peripheral (n = 1) locations in the ablation zones. Thrombosis was decreased in nine (69.2%), persisted in one (7.6%), and increased in three (23.0%) of 13 patients who underwent follow-up CT for more than 12 months. Local tumor progression was noted in four patients (26.6%); it abutted to venous thrombosis in two patients, separated from the venous thrombosis in one patient, and exhibited malignant thrombosis in one patient., Conclusion: The development of portal or hepatic venous thromboses after RFA in patients with HCC is rare and usually is associated with favorable prognoses. Further investigation is warranted to elucidate whether venous thrombosis after RFA is related to local tumor progression around ablation zones.

Objective: This study was designed to assess the effect of artificial ascites on thermal protection of the diaphragm and the therapeutic efficacy of this technique during percutaneous radiofrequency ablation for hepatocellular carcinoma abutting the diaphragm., Materials and Methods: A total of 44 patients with a single nodular hepatocellular carcinoma (< 4 cm; mean, 2.2 cm) that abutted the diaphragm were treated with ultrasound-guided percutaneous radiofrequency ablation as first-line treatment. The patients were divided into two groups: a group who received artificial ascites (n = 20) and a control group (n = 24). We compared the two groups in an assessment for change in diaphragmatic thickness, right shoulder pain, and transient lung injury as indicators of thermal injury to the diaphragm. We evaluated therapeutic efficacy with follow-up CT., Results: Swelling of diaphragm at immediate follow-up CT was more severe in the control group (mean change in thickness, 0.56 mm versus 1.55 mm; p = 0.01). Right shoulder pain (n = 1 versus n = 7) and transient lung injury (n = 0 versus n = 6) occurred statistically significantly more often in the control group than the artificial ascites group, but pleural effusion did not (n = 13 versus n = 1). The technical success rate was higher in the artificial ascites group (100% versus 79%, p = 0.06). There was no significant difference in effectiveness rate of the primary technique (100% versus 92%, p = 0.49) or rate of local tumor progression (20% versus 30%, p = 0.47)., Conclusion: The use of artificial ascites for percutaneous radiofrequency ablation of hepatocellular carcinoma abutting the diaphragm had a significant effect on thermal protection of the diaphragm but not on therapeutic efficacy.

Objective: The objective of our study was to evaluate the frequency, morphologic patterns, temporal changes, and clinical significance of biloma after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC)., Materials and Methods: Between April 1999 and May 2008, 2,630 patients with HCC underwent a total of 3,284 sessions of RFA at our institution. We retrospectively reviewed all CT scans obtained before and after RFA in all patients. The frequency, morphologic patterns, temporal changes, and clinical course of biloma were studied at the thermal ablation zone after RFA., Results: A total of 109 bilomas (3.3%, 109/3,284) developed after RFA in 104 patients in our series. The bilomas developed from 0 to 526 days (mean, 64 days) after RFA, and the mean follow-up period was 469 days (range, 0-2,703 days). The most common morphologic type of biloma was a crescent shape (42.2%). The mean size of the bilomas at initial presentation was 3.8 cm (range, 1.7-11 cm), and the mean size of the bilomas on the last follow-up CT scan was 2.8 cm (range, 0-6.3 cm). Fifty-three (48.6%) of the 109 bilomas resolved during follow-up at a mean interval of 286 days. In one patient, the biloma was considered a major complication because percutaneous drainage was required to manage the biloma with infection (0.9%, 1/109). No patient died of a biloma., Conclusion: The development of a biloma after percutaneous RFA in patients with HCC was not rare. However, in most cases they were a minor complication of no clinical significance.

Objective: The aim of this study was to elucidate the minimal ablative margin for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) (> 2 and < 5 cm) needed to prevent local tumor progression using CT image fusion and a 3D quantitative method., Materials and Methods: From April 2005 to March 2007, we performed percutaneous RFA for the treatment of 382 HCCs larger than 2 cm and smaller than 5 cm. A total of 110 tumors in 103 patients (77 men and 26 women; mean age, 59.7 years) that were previously untreated and were monitored for at least 1 year were retrospectively enrolled. A 5-mm safety margin was attempted in all cases, and a CT finding of complete replacement of the index tumor by RFA zone was defined as technical success. We constructed fusion images of CT images obtained before and after RFA and performed radial multiplanar reformation with the rotation axis at the center of the tumor to analyze the ablative margin quantitatively. Risk factors for local tumor progression (the thinnest ablative margin, tumor size, and the effect of hepatic vessels) were assessed by multivariate analysis., Results: Patients underwent follow-up for 12.9-46.6 months (median, 28.1 months). The tumors were 2.1-4.8 cm (mean +/- SD, 2.7 +/- 0.6 cm) in diameter. The thinnest ablative margins ranged from 0 to 6 mm (1.0 +/- 1.4 mm). A 5-mm safety margin was achieved in only 2.7% (3/110) of cases. In 47.3% (52/110) of cases, vessel-induced indentation of the ablation zone contributed to the thinnest ablative margins. Local tumor progression was detected in 27.3% (30/110) of cases. Concordance between local tumor progression and the thinnest margin was observed in 83.3% (25/30) of cases. The incidence of concordant local tumor progression was 22.7% (25/110), 18.9% (10/53), 5.9% (2/34), and 0% (0/15) in tumors with the thinnest ablative margin of > or = 0, > or = 1, > or = 2, and > or = 3 mm, respectively. An insufficient ablative margin was the sole significant factor associated with local tumor progression., Conclusion: When the thickness of the ablative margin is evaluated by CT image fusion, a margin of 3 mm or more appears to be associated with a lower rate of local tumor progression after percutaneous RFA of HCC.

Objective: The aims of this study were to evaluate the pattern of vital sign changes and to elucidate significant risk factors for severe cardiovascular inhibition caused by percutaneous hepatic radiofrequency ablation (RFA)., Subjects and Methods: A total of 102 patients (male-to-female ratio, 73:29; age range, 35-85 years; mean age, 58.1 years) with 119 malignant hepatic tumors were enrolled and analyzed prospectively. The patients underwent percutaneous RFA with IV infusion of opioid analgesics. Changes in blood pressure (BP) and heart rate (HR) and the occurrence of significant cardiovascular inhibition (BP or HR < 70% of baseline) were monitored during the procedure. Respiratory rate and skin body temperature were recorded before and after the procedure., Results: Whereas the mean BP was elevated (36%, 43/119) or depressed (36%, 43/119) with a similar frequency, the HR was predominantly depressed (56%, 66/119) during the procedure. The BP and HR were stable in only 18% cases (21/119), respectively. The respiratory rate showed no significant change (p = 0.521) after RFA; however, body temperature decreased (p < 0.001) after RFA. Although significant cardiovascular inhibition occurred in 41 cases (35%), all of the cases could be managed successfully and the technical success rate was 100% (119/119). Among the risk factors analyzed, old age (B = -0.003, p = 0.019) was significant for systolic BP depression, and contact of the RFA zone with the central portal vein (B = -0.096, p = 0.014) and female sex (B = -0.078, p = 0.033) were significant risk factors for HR depression as determined by multivariate analysis., Conclusion: Changes in BP and HR, especially bradycardia, are common during percutaneous RFA of hepatic lesions. Significant risk factors for severe cardiovascular inhibition include contact of the RFA zone with the branches of the central portal vein, old age, and female sex.

Objective: This study was designed to assess whether artificial ascites has a heat-sink effect on the ablation zone for percutaneous radiofrequency ablation (RFA) of hepatic tumors abutting the diaphragm., Materials and Methods: We retrospectively assessed 28 patients who underwent percutaneous RFA for the treatment of a single nodular hepatic tumor that abutted the diaphragm from July 2000 to December 2006. All patients underwent ultrasound-guided RFA using internally cooled electrodes. A single ablation for 12 minutes was applied using 3-cm active-tip electrodes. We divided patients into two groups on the basis of whether artificial ascites was introduced before RFA: Group A consisted of patients who received artificial ascites with a mean of 760 mL of a 5% dextrose in water solution (n = 15) and group B consisted of patients who did not receive artificial ascites (n = 13). The volume of the ablation zone was measured on CT images obtained immediately after the ablation procedure, and imaging findings were compared for both groups using the Student's t test. We also compared the local tumor progression rate between both groups using the chi-square test (mean follow-up, 37.4 months)., Results: There was no significant difference between the two patient groups with regard to age, sex, Child-Pugh class, or tumor location (p > 0.05). The tumors were significantly smaller in group A patients (mean +/- SD, 1.6 +/- 0.5 cm) than in group B patients (2.1 +/- 0.7 cm) (p = 0.019). The mean volume of the RFA zone was 31.6 +/- 11.9 cm(3) in group A patients and 30.9 +/- 11.0 cm(3) in group B patients. There was no significant difference between the groups in the ablation volume (p = 0.871). Local tumor progression was noted in four patients (26.7%) in group A and in three patients (23.1%) in group B. There was no significant difference in the local tumor progression rate between the two groups (p = 0.83)., Conclusion: Artificial ascites did not show a heat-sink effect on the volume of the ablation zone after percutaneous RFA for the treatment of a hepatic tumor abutting the diaphragm.

Objective: The objective of our study was to assess whether percutaneous radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is a safe procedure in patients with ascites., Materials and Methods: From October 2005 to January 2008, 35 patients with one or more HCCs and ascites were referred to our department for planning sonography of RFA. In 15 patients, RFA was determined to be unfeasible. One patient was excluded from the study because of the absence of ascites at the time of RFA. Percutaneous ultrasound-guided RFA was performed in the remaining 19 patients with 24 HCCs. The electrode tract was cauterized at the time of electrode removal. Retrospective assessments of the preprocedural platelet counts and prothrombin times were performed, and patients were evaluated for bleeding complication by checking vital signs, checking serum hemoglobin level, and using CT to determine whether the attenuation value of ascites had increased > 30 HU., Results: There were no cases of mortality or major complications that developed after RFA. No significant difference in the maximum thickness of the perihepatic ascites and in the hemoglobin level between the pre- and postprocedural measurements was detected. Hemoperitoneum as a minor complication was noted in two (10.5%) of 19 patients. However, in those two patients, vital signs were stable, follow-up laboratory data were normal, and hemoperitoneum had been completely absorbed on CT images obtained 1 month after RFA., Conclusion: Percutaneous RFA for HCC can be performed safely in patients with ascites.

Objective: The purpose of our study was to elucidate whether the degree of arterial enhancement on CT is a significant risk factor for local tumor progression after percutaneous radiofrequency ablation of hepatocellular carcinomas (HCCs) larger than 2 cm., Materials and Methods: Percutaneous radiofrequency ablation procedures to treat 203 previously untreated HCCs larger than 2 cm in 190 patients were analyzed retrospectively. We assessed the technique effectiveness rate 1 month after the procedure and the cumulative local tumor progression rate. The tumors were classified into one of the following groups for qualitative analysis: group with evident contrast enhancement or group showing subtle or no contrast enhancement. We performed quantitative analysis of increments in the attenuation (in Hounsfield units [HU]) from unenhanced to arterial phase CT of the 78 HCCs for which unenhanced CT was available. To determine any significant risk factor, various factors, including the degree of arterial enhancement, were tested by multivariate analysis., Results: The technique effectiveness rate was 99.0% (201/203). Local tumor progression was detected in 23.9% (48/201), and the cumulative rates of local tumor progression at 1, 2, and 3 years were 12.9%, 23.1%, and 27.6%, respectively. The two qualitative groups were significantly different in their cumulative local tumor progression rates (p = 0.009). Multivariate analysis revealed that the degree of arterial enhancement was a sole independent significant risk factor for local tumor progression (p = 0.026)., Conclusion: A high degree of arterial enhancement on CT after percutaneous radiofrequency ablation of HCCs larger than 2 cm is a significant risk factor for local tumor progression.

Objective: We compared the diagnostic performance of gadoxetic acid-enhanced MRI with that of triple-phase 16-, 40-, and 64-MDCT in the preoperative detection of hepatocellular carcinoma (HCC)., Subjects and Methods: Sixty-two consecutively registered patients (54 men, eight women; age range, 31-67 years) with 83 HCCs underwent triple-phase (arterial, portal venous, equilibrium) CT at 16-, 40-, or 64-MDCT and gadoxetic acid-enhanced 3-T MRI. The diagnosis of HCC was established after surgical resection. Three observers independently and randomly reviewed the MR and CT images on a tumor-by-tumor basis. The diagnostic accuracy of these techniques in the detection of HCC was assessed with alternative free response receiver operating characteristic (ROC) analysis. Sensitivity, positive and negative predictive values, and sensitivity according to tumor size were evaluated., Results: For each observer, the areas under the ROC curve were 0.971, 0.959, and 0.967 for MRI and 0.947, 0.950, and 0.943 for CT. The differences were not statistically significant between the two techniques for each observer (p > 0.05). The differences in sensitivity and positive and negative predictive values between the two techniques for each observer were not statistically significant (p > 0.05). Among 10 HCCs 1 cm in diameter or smaller, each of the observers detected seven tumors with MRI. With CT, one observer detected five, one observer detected four, and one observer detected three HCCs with no statistically significant difference (p > 0.05)., Conclusion: Gadoxetic acid-enhanced MRI and triple-phase MDCT have similar diagnostic performance in the preoperative detection of HCC, but MRI may be better than MDCT in the detection of HCC 1 cm in diameter or smaller.

Objective: The purpose of our study was to evaluate the factors related to intraprocedural and postprocedural pain during radiofrequency ablation of hepatocellular carcinomas (HCCs)., Materials and Methods: For this retrospective study, we included 145 patients with 160 HCCs who underwent percutaneous radiofrequency ablation under local and IV conscious sedation from January 2006 to December 2006. Patients' pain was scored using the visual analog scale (VAS) immediately after the procedure. Medical records with CT images were reviewed for patient factors, tumor characteristics, and procedural factors. We determined factors correlated with the higher level of intraprocedural pain and the difference in intraprocedural VAS between a group requiring additional analgesics while hospitalized and a group not requiring more analgesics. Statistical analysis was performed using the two-sample Wilcoxon's rank sum test, the Kruskal-Wallis test, and partial Spearman's correlation analysis., Results: On univariate analysis, patients with large tumors, previously untreated tumors, tumors adjacent to the parietal peritoneum, and those who had undergone multiple ablations and longer duration of ablation reported a higher VAS during the procedure. A significant correlation was seen between the distance of a tumor from the parietal peritoneum and the VAS. On multivariate analysis, tumor location adjacent to the parietal peritoneum was an independent predictor for a higher level of self-reported pain. A group requiring additional analgesics while hospitalized reported a higher VAS than patients not requiring more analgesics., Conclusion: The location of a tumor adjacent to the parietal peritoneum is an independent predictor of higher pain level during percutaneous radiofrequency ablation of HCCs. Modification of intraprocedural anesthesia should be considered in patients with risk factors for increased pain.

Objective: The purpose of this study was to evaluate the CT features and growth rates of recurrent retroperitoneal liposarcoma on follow-up CT scans., Conclusion: Retroperitoneal liposarcoma frequently recurs asymptomatically within 2 years, usually within 6 months-2 years, of the initial surgical resection. The CT features of recurrent liposarcoma are similar to those of the initial manifestation; recurrent liposarcoma shows rapid growth, with a mean tumor volume doubling time of 98 days (range, 46-151 days; median, 104 days).

Objective: The purpose of this study was to evaluate with serial follow-up CT examinations the growth rate of new hepatocellular carcinoma (HCC) developing after percutaneous radiofrequency ablation and to determine an appropriate follow-up interval for imaging., Materials and Methods: Sixty-two new HCCs appearing after percutaneous radiofrequency ablation in 59 patients who underwent follow-up multiphase CT were retrospectively identified. The volume of the new HCCs at follow-up CT was measured on a PACS monitor with an area measuring tool and summation-of-areas technique. We calculated tumor volume doubling time and tumor diameter doubling time. The growth rate was represented by tumor volume doubling time. We also used stepwise multiple linear regression analysis to evaluate the relation between clinical variables and tumor volume doubling time., Results: Mean baseline and follow-up tumor volumes were 580 mm(3) (range, 85-13,861 mm(3)) and 2,072 mm(3) (range, 535-35,937 mm(3)). Mean baseline and follow-up tumor diameters were 9.9 mm (range, 5.5-29.8 mm) and 15.0 mm (range, 10.1-40.9 mm). Mean tumor volume and tumor diameter doubling times were 75 days (range, 21-209 days) and 219 days (range, 57-897 days). Volume doubling times of baseline tumors with a diameter of 1 cm or less were significantly shorter than those of the larger baseline tumors (mean, 55 vs 88 days; p = 0.024)., Conclusion: The growth rate of new HCCs after percutaneous radiofrequency ablation was higher than that reported in natural outcome studies of untreated HCCs. The results of our study suggest that a shorter follow-up interval for imaging, 2.5 months (75 days), is appropriate.

Objective: The purpose of our study was to assess the morphologic pattern and exact site of local tumor progression with relation to various risk factors after radiofrequency ablation of liver tumors., Conclusion: Local tumor progression after radiofrequency ablation shows mostly the peripheral nodular type. The site of local tumor progression shows a higher concordance rate with insufficient ablative margin than contiguous vessel and subcapsular location.

Objective: The purpose of this study was to evaluate the effect of artificial ascites on thermal injury to the diaphragm and stomach in a porcine model of radiofrequency ablation of the liver., Materials and Methods: We performed this study using eight pigs in experimental and control groups of four pigs each. Artificial ascites was produced before radiofrequency ablation to separate the liver from the diaphragm and the stomach in the experimental group. Using a 1-cm exposed internally cooled radiofrequency electrode for 5 minutes, we performed 74 hepatic ablations abutting the diaphragm and stomach. CT was performed on the day of the procedure and 7 days after ablation. The pigs were sacrificed, and necropsy was performed. We performed pathologic and CT examinations to compare the frequency and extent of thermal injury to the two organs., Results: The mean number of radiofrequency ablations in each pig was 9.3 (range, 6-12). The mean number of ablation zones adjoining the diaphragm was 5.5 (range, 3-8) and of zones contiguous with the stomach was 3.8 (range, 3-4). Thermal injury to the adjacent organs occurred more frequently in the control group than in the experimental group (p < 0.05). The major complications of diaphragmatic hernia and gastric perforation occurred only in the control group. No major complications were identified in the experimental group at necropsy. The sizes of the radiofrequency ablation zone of the liver did not differ between the two groups (p > 0.05). The mean diameters of the diaphragmatic and gastric lesions did differ (p < 0.05). Histopathologic examination revealed a significant difference in the depths of thermal injury in the two groups (p < 0.05)., Conclusion: Artificial ascites may be a simple and useful technique for reducing the frequency and severity of collateral thermal injury to the diaphragm and stomach during radiofrequency ablation of subcapsular hepatic tumors.

Objective: The objective of our study was to evaluate the feasibility rate and the reasons for infeasibility of percutaneous radiofrequency ablation of hepatocellular carcinomas (HCCs) at planning sonography., Materials and Methods: We retrospectively evaluated 248 patients who had been referred for planning sonography at our department between October 2005 and February 2006. We reviewed the radiologic reports of 256 planning sonography examinations in terms of the rate of feasible cases and the reasons for infeasibility. The reasons for infeasibility were classified in six categories: an inconspicuous tumor, an inadequate electrode path, an organ vulnerable to collateral thermal damage, a tumor that was too large or too many tumors, and a high risk of the heat sink effect. In addition, we assessed the treatment modality for the patients who were determined to have HCCs for which percutaneous radiofrequency ablation was not feasible., Results: In 141 (55%) of the 256 planning sonography examinations, percutaneous radiofrequency ablation was feasible. The remaining 115 (45%) planning sonography examinations revealed that radiofrequency ablation was not a feasible procedure. The reasons for infeasibility included an inconspicuous tumor in 77 patients (55.8%), an inadequate electrode path in 33 patients (23.9%), an organ vulnerable to collateral thermal damage in 14 patients (10.1%), a tumor that was too large or too many tumors in eight patients (5.8%), a high risk of the heat sink effect in five patients (3.6%), and a portal vein thrombosis in one patient (0.7%). One reason for infeasibility was found in 96 patients, two reasons in 19 patients, and four reasons in one patient. Seventy (61.9%) of 113 patients for whom radiofrequency ablation was not feasible underwent transcatheter arterial chemoembolization as an alternative treatment., Conclusion: In approximately half of the patients for whom percutaneous radiofrequency ablation of HCC is requested, the procedure is not feasible, mainly due to inconspicuous tumors, at planning sonography. Additional objective criteria for assessing the feasibility of radiofrequency ablation and therapeutic strategies according to the reasons for infeasibility should be investigated further.

Objective: The purpose of our study was to evaluate the histopathologic changes of gallbladder wall surrounding radiofrequency ablation zones in pig livers and to assess the risk factors for thermal injury of gallbladder wall in terms of distance of the electrode, electrode direction in relation to the gallbladder wall, and time of sacrifice of the animal., Materials and Methods: The study was performed in 15 pigs using an internally cooled single electrode with a 1-cm electrically active tip under sonographic guidance. Twenty-three hepatic ablation zones abutting the gallbladder were analyzed in three phases on the basis of the distance of the electrode (group A, 0.5 cm; group B, 1.0 cm), electrode direction (perpendicular or parallel), and time of sacrifice (immediate or delayed [7 days after radiofrequency ablation]). We evaluated the gross changes, the depth of thermal injury, and the grade of abnormal microscopic changes in the gallbladder wall. Data analysis was performed on the basis of the Fisher's exact test., Results: Discoloration and perforation were more frequent in group A (60%, 6/10, and 20%, 2/10, respectively) than in group B (25%, 2/8, and 0%, respectively, p > 0.05). Perforation was more frequent in the parallel direction and delayed phase (33.3%, 1/3, and 40%, 2/5, respectively) compared with the perpendicular direction and immediate phase (14.3%, 1/7, and 0%, respectively, p > 0.05). Depth of thermal injury showed a significant difference between group A and group B for full-thickness involvement (53.8%, 7/13, versus 0%, respectively, p < 0.05). Abnormal microscopic changes showed that parallel direction and immediate phase were more frequent with full-thickness involvement (71.4%, 5/7, and 71.4%, 5/7, respectively) compared with perpendicular direction and delayed phase (33.3%, 2/6, and 33.3%, 2/6, respectively, p > 0.05)., Conclusion: Hepatic radiofrequency ablation abutting the gallbladder can produce substantial thermal injury of the gallbladder wall, including perforation, especially when performed without a safe distance.

Objective: Our objective was to assess the feasibility, safety, and efficacy of percutaneous radiofrequency ablation with artificial ascites for hepatocellular carcinoma (HCC) in the hepatic dome., Materials and Methods: Sonographically guided percutaneous radiofrequency ablation with artificial ascites was performed in 25 patients with 34 HCCs using an internally cooled electrode radiofrequency system. At least one hepatic dome tumor in each patient was considered difficult to treat percutaneously because of partially visible tumor (n = 16) or poor electrode path (n = 9) on planning sonography. We artificially induced ascites before radiofrequency ablation by dripping 5% dextrose in water (D/W) solution to improve tumor visibility or electrode path and to separate the radiofrequency ablation zone from the diaphragm. We assessed the technical feasibility, safety, and efficacy of this technique with clinical and CT follow-up for at least 4 months (mean, 281.4 days), Results: Artificial ascites was successfully achieved in 22 (88%) of 25 patients with the administration of a mean of 348 mL of D/W solution for an additional mean time of 9.3 minutes. There was substantial improvement in the visibility in 93.4% (15/16) of the partially visible tumors and in achieving a better path in 77.8% (7/9) of the tumors with a poor electrode path. The primary technique effectiveness rate for hepatic dome tumors was 96% (24/25) at 1-month follow-up CT. There was no diaphragmatic thermal injury in all but one case. No complication related to artificial ascites occurred during the follow-up period., Conclusion: Percutaneous radiofrequency ablation with artificial ascites appears a feasible, safe, and effective technique for treating HCC of the hepatic dome.

Objective: The purpose of this study was to elucidate on the basis of clinicoradiologic features the patterns of and prognostic factors for recurrence of hepatocellular carcinoma after liver transplantation., Materials and Methods: Institutional review board approval and informed consent were waived for this retrospective study. The subjects were 119 patients (102 men, 17 women; mean age, 49.8 years) with unresectable hepatocellular carcinoma who underwent liver transplantation from September 1996 to May 2005 and survived more than 2 months. We evaluated the incidence, imaging features, cumulative disease-free survival rate, and prognosis for recurrence of hepatocellular carcinoma. We examined clinical, therapeutic, and pretransplantation contrast-enhanced CT findings as prognostic factors and analyzed them with multivariate analysis. The median follow-up period was 17.2 months (range, 2.0-102.4 months)., Results: Recurrence was found in 16 (13.4%) of 119 patients and was most frequent in the liver, with no specific pattern. A multivariate stepwise Cox hazard model showed that the presence of portal venous thrombosis, more than 3-cm diameter of the largest tumor, and a viable tumor volume ratio greater than 10% were statistically independent prognostic factors. The 3- and 5-year cumulative disease-free survival rates for the entire cohort were 82.1% and 76.6%, respectively. Despite local therapy for a solitary metastatic lesion, recurrences were common. The mortality rate among patients with recurrent disease was 56.3%., Conclusion: Recurrence of hepatocellular carcinoma after liver transplantation is common, and the prognosis is not favorable. The presence of portal venous thrombosis and tumor size greater than 3 cm on baseline CT are significant risk factors. Aggressive interventional therapy seems to be helpful as a bridge to liver transplantation.

Objective: Our objective was to compare the prognosis of subcapsular and nonsubcapsular hepatocellular carcinoma after percutaneous radiofrequency ablation using multitined expandable electrodes., Materials and Methods: Some controversies exist about the clinical usefulness of percutaneous radiofrequency ablation of subcapsular hepatocellular carcinoma. Twenty-eight patients underwent percutaneous radiofrequency ablation of 43 hepatocellular carcinomas using multitined expandable electrodes. Twelve tumors were subcapsular and 31 were nonsubcapsular. We attempted to use normal liver as a pathway to the tumor when possible. Tumor size ranged from 1.0 to 4.2 cm (mean, 1.8 cm). Median follow-up was 16 months. Initial ablation was considered to have been complete when no enhancement was seen in the region of the ablated lesion on 1-month follow-up CT or on follow-up CT performed immediately after repeated ablation. Initial complete ablation and local tumor progression rates were compared between subcapsular and nonsubcapsular tumors. Eleven patients had subcapsular tumors (group 1), whereas the other 17 patients did not have subcapsular tumors (group 2). Major complication and mortality rates were compared between the two groups., Results: No significant differences in initial complete ablation rate (100% vs 96.7%, p = 1.000) or local tumor progression rate (0% vs 10.0%, p = 0.545) were found between subcapsular and nonsubcapsular tumors. No procedure-related major complication or mortality occurred. The overall 1- and 3-year survival rates were 89.3% and 60.3%, respectively., Conclusion: The rates of local tumor progression and complications for radiofrequency ablation using multitined expandable electrodes for subcapsular hepatocellular carcinomas were comparable to those for nonsubcapsular hepatocellular carcinomas.

Objective: The purpose of our study was to assess the therapeutic results of radiofrequency ablation of hepatocellular carcinoma (HCC) based on the histologic grades of the tumors., Subjects and Methods: Between April 1999 and December 2003, 95 patients with nodular HCC were treated with percutaneous radiofrequency ablation. All tumors were histologically proven by sonography-guided percutaneous biopsy and were classified as Edmondson-Steiner grade I HCC (n = 38) (mean, 2.3 cm) (group 1), grade II HCC (n = 50) (mean, 2.4 cm) (group 2), or grade III HCC (n = 7) (mean, 2.8 cm) (group 3). All patients underwent contrast-enhanced three-phase helical CT examination before and after radiofrequency ablation. After retrospective review of the medical records and follow-up CT examinations, the rates of technique effectiveness, local tumor progression, cumulative survival, and cancer-free survival using a Kaplan-Meier method were calculated and compared among the groups., Results: Technique effectiveness rates in groups 1, 2, and 3 were 87% (27/31), 71% (30/42), and 43% (3/7), respectively, with statistical significance (p = 0.032). Local tumor progression rates in groups 1, 2, and 3 were 16% (5/31), 36% (15/42), and 71% (5/7), respectively, with statistical significance (p = 0.013). Five-year cumulative survival rates in groups 1, 2, and 3 were 71%, 44%, and 43%, respectively, with no statistical significance (p > 0.05). Four-year cancer-free survival rates in groups 1, 2, and 3 were 39%, 10%, and 0%, respectively (p < 0.05 for groups 1 vs 2; p > 0.05 for groups 1 vs 3 and groups 2 vs 3)., Conclusion: The histologic grade of HCC is an important factor influencing therapeutic results with survival after radiofrequency ablation.

Objective: The purpose of this study was to evaluate the doubling time, frequency, and features on dynamic CT of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy for hepatocellular carcinoma (HCC)., Materials and Methods: Between January 1997 and June 2003, 1,055 patients underwent sonographically guided percutaneous biopsy for HCC. The serial changes of implanted tumor volume were estimated on retrospective review of CT, and their doubling times were calculated from the two CT scans showing the first and last visible implanted tumors. The frequency of extrahepatic needle tract implantation of malignant neoplasms was evaluated overall and according to the type of needle used. The CT features of the implanted tumors were examined with regard to size, number, location, morphology, and enhancement pattern., Results: The mean doubling time of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy was 112 days (range, 22-415 days). The mean time interval between biopsy and the emergence of the implanted tumor on CT was 267 days (range, 116-619 days). The overall frequency was 0.76% (8/1,055). The frequencies according to the type of needle were 1.3% (8/622) for the group treated with the end-cutting needle and 0% (0/433) for the group treated with the tru-cut needle; these frequencies differ from each other with statistical significance (p < 0.05, Fisher's exact test). Fifteen of the 17 implanted tumors were round or oval enhancing nodules along the needle tract, and 13 showed persistent enhancement on equilibrium phase images., Conclusion: The doubling times of extrahepatic needle tract implantation of malignant neoplasms after sonographically guided percutaneous biopsy for HCC were similar to those of typical HCCs in the liver on CT-based analysis. The frequency was relatively low, and their CT features were similar to those reported previously.

Objective: The purpose of this study was to clarify the frequency and risk factors of liver abscess formation after percutaneous radiofrequency ablation in patients with hepatocellular carcinoma., Materials and Methods: Over a 4-year period, 603 patients with 831 hepatocellular carcinomas measuring 5 cm or less in maximum diameter who underwent a total of 751 percutaneous radiofrequency ablation procedures were enrolled in this study. We retrospectively reviewed the medical records and analyzed the overall frequency of liver abscess, risk factors for abscess, and clinical features of the patients. The relationships between liver abscess and potential risk factors were analyzed using either generalized estimating equations or multiple logistic regression analysis., Results: Liver abscess developed in 14 tumors of 13 patients after 13 (13/751 [1.7%]) ablation procedures. Generalized estimating equations and multiple logistic regression analysis of various potential risk factors revealed that preexisting biliary abnormality prone to ascending biliary infection (p = 0.0088), tumor with retention of iodized oil from previous transcatheter arterial chemoembolization (p = 0.040), and treatment with an internally cooled electrode system (p = 0.016) were associated with a significant risk of liver abscess formation. No patient died of liver abscess, and all successfully recovered from liver abscess with parenteral antibiotics and percutaneous clearance of pus., Conclusion: Although liver abscess formation was infrequent in patients who underwent percutaneous radiofrequency ablation for hepatocellular carcinoma, the patients with significant risk factors-preexisting biliary abnormality prone to ascending biliary infection, tumor with retention of iodized oil, and treatment with an internally cooled electrode system-for liver abscess formation should be closely monitored after treatment.

Objective: We compared ferucarbotran-enhanced MRI with triple-phase MDCT for the preoperative detection of hepatocellular carcinoma., Subjects and Methods: Seventy-three consecutive patients with 121 hepatocellular carcinomas underwent ferucarbotran-enhanced MRI, including a dynamic study, and triple-phase MDCT before hepatic resection. The diagnosis of hepatocellular carcinoma was confirmed in all patients by means of pathologic examination after surgical resection. Three experienced radiologists independently reviewed the MR and CT images on a segment-by-segment basis. The accuracy of these techniques for the detection of hepatocellular carcinoma was assessed by conducting a receiver operating characteristic (ROC) analysis of the observations of 88 resected hepatic segments with at least one hepatocellular carcinoma each and 121 resected hepatic segments without hepatocellular carcinoma., Results: The mean values of the area under the ROC curve (A(z)) for ferucarbotran-enhanced MRI and triple-phase MDCT for all observers were 0.947 and 0.949, respectively; the difference between these two values was not statistically significant (p = 0.799). The mean sensitivities of MRI and triple-phase MDCT were 90.2% and 91.3%, respectively, and their mean specificities were 97.0% and 95.3%, respectively. The differences in the mean sensitivities and specificities of these two imaging techniques were not statistically significant (p > 0.05 in each case)., Conclusion: Ferucarbotran-enhanced MRI seems to be as accurate as triple-phase MDCT for the preoperative detection of hepatocellular carcinoma.

Objective: The purpose of our study was to determine the frequency of bile duct changes after radiofrequency ablation for hepatocellular carcinoma and to evaluate their clinical significance., Materials and Methods: Between April 1999 and August 2003, 389 patients with 521 hepatocellular carcinomas underwent a total of 571 sessions of radiofrequency ablation. The maximum dimension of the tumors measured on sonography was 2.4 +/- 0.9 cm (mean +/- SD) (range, 0.5-5.0 cm). The frequency and type of bile duct changes resulting from radiofrequency ablation, the time interval between radiofrequency ablation and the first appearance of bile duct changes, and the serial changes at follow-up CT were analyzed. Complications related to bile duct changes were also evaluated by reviewing medical records and CT scans., Results: Bile duct changes occurred in 69 (12%) of 571 sessions and 66 (17%) of 389 patients. Bile duct changes seen on CT included mild dilatation of upstream bile ducts surrounding the ablation zone in 57 patients (82.6%), biloma in the ablation zone in four patients (5.8%), and both in eight patients (11.6%). The mean time interval between radiofrequency ablation and the initial appearance of bile duct change was 1.6 months (range, immediate-9 months). Most (87%) of the 69 patients with bile duct changes showed no progression on follow-up CT, and only nine (13%) had slight progression. All patients but one, in whom cholangitis developed, had no major complications requiring specific treatment during the follow-up period., Conclusion: Although bile duct changes were frequent after the radiofrequency ablation of hepatocellular carcinoma, most were of no clinical significance, and major complications requiring additional treatment were rare.

Objective: The purpose of this study was to evaluate the therapeutic efficacy and safety of percutaneous radiofrequency ablation in the treatment of hepatocellular carcinomas abutting the gastrointestinal tract., Materials and Methods: Forty-one patients with hepatocellular carcinomas abutting the gastrointestinal tract underwent sonographically guided percutaneous radiofrequency ablation. Forty-one tumors (1.2-4.3 cm in maximum diameter) had parts 5 mm or greater (or at least one quarter of their circumferences) abutting the stomach in 23 patients and the colon in 18 patients. Thirty tumors were ablated with internally cooled electrodes and 11 with multitined expandable electrodes. All patients were followed up for at least 1 year after ablation. Therapeutic efficacy and safety were evaluated with follow-up sonography and multiphase helical CT., Results: At 1-month follow-up CT, three (7%) of the 41 tumors showed residual unablated tumor in the ablation zone. Of the remaining 38 hepatocellular carcinomas (93%) with no evidence of residual unablated tumor, four (11%) showed local tumor progression in the ablation zones on subsequent follow-up CT. We observed one major complication-a small perihepatic abscess-that needed specific treatment., Conclusion: Percutaneous radiofrequency ablation is an effective and safe technique for treating hepatocellular carcinomas abutting the gastrointestinal tract.

Objective: The purpose of our study was to evaluate the efficacy of imaging-guided percutaneous radiofrequency ablation of metastatic pulmonary nodules caused by hepatocellular carcinoma., Conclusion: Percutaneous radiofrequency ablation is feasible and can be a promising method for the local control of metastatic pulmonary nodules caused by hepatocellular carcinoma, especially when they are limited in number.

Objective: The purpose of our study was to compare the diagnostic accuracy and lesion conspicuity of ferumoxides-enhanced MR imaging with those of mangafodipir trisodium-enhanced MR imaging for the preoperative detection of hepatocellular carcinoma., Subjects and Methods: Twenty-one patients with 39 hepatocellular carcinomas underwent ferumoxides-enhanced and mangafodipir trisodium-enhanced MR imaging. The diagnosis was established by pathologic examination after surgical resection in all patients. Five MR sequences were obtained 30 min after ferumoxides administration, and two MR sequences were obtained before and 15 min after mangafodipir trisodium administration. Three observers independently interpreted both MR images of all sequences on a segment-by-segment basis. The diagnostic accuracy of MR imaging was assessed using receiver operating characterizing analysis. Lesion (hepatocellular carcinoma > 10 mm in diameter)-to-liver contrast-to-noise ratio was calculated on MR images., Results: Ferumoxides-enhanced MR imaging (A(z) = 0.971) was significantly more accurate (p < 0.05) than mangafodipir trisodium-enhanced MR imaging (A(z) = 0.950). The mean sensitivity of ferumoxides-enhanced MR imaging (86%) was significantly greater (p < 0.05) than that of mangafodipir trisodium-enhanced MR imaging (44%) in lesions smaller than 10 mm. The mean lesion-to-liver contrast-to-noise ratio of hepatocellular carcinoma on ferumoxides-enhanced MR imaging (13.7 +/- 8.8) was significantly greater than on mangafodipir trisodium-enhanced MR imaging (5.4 +/- 5.1) (p < 0.01)., Conclusion: Ferumoxides-enhanced MR imaging has superior diagnostic accuracy in lesions smaller than 10 mm and superior lesion conspicuity compared with mangafodipir trisodium-enhanced MR imaging for the preoperative detection of hepatocellular carcinoma.

Objective: The purpose of our study was to determine the value of adding delayed phase imaging to dual-phase helical CT for the detection of hepatocellular carcinoma., Subjects and Methods: One hundred thirteen patients with 131 hepatocellular carcinomas underwent triple-phase helical CT. The diagnosis was established by pathologic examination after surgical resection in all patients. For triple-phase helical CT, hepatic arterial, portal venous, and delayed phase scanning began 30, 60, and 180 sec, respectively, after the injection of 120 mL of iodinated contrast material. Dual-phase helical CT excluding delayed phase and triple-phase helical CT images were reviewed independently by three radiologists on a segment-by-segment basis. Diagnostic accuracy was assessed using receiver operating characteristic analysis in 330 resected segments. Sensitivities and specificities were calculated. The value of the delayed phase images in the characterization of hepatocellular carcinoma was also assessed., Results: The diagnostic accuracy of triple-phase helical CT including delayed phase (area under the curve [A(z)], 0.973) was significantly higher than that of dual-phase helical CT (A(z), 0.954). The mean sensitivity of triple-phase CT (89%) was also significantly higher than that of dual-phase CT (86%). The mean specificities of triple-phase CT (99%) and dual-phase CT (99%) were equal. Delayed phase images were helpful in the characterization of hepatocellular carcinoma in 14% of patients., Conclusion: The addition of delayed phase imaging to dual-phase helical CT is valuable for the detection and characterization of hepatocellular carcinoma.

Objective: The purpose of this study was to describe helical CT findings of gastric mucosa-associated lymphoid tissue (MALT) lymphoma and to correlate them with pathologic findings., Materials and Methods: We retrospectively reviewed CT examinations of 58 patients with confirmed gastric MALT lymphomas. Using the histopathologic grade of the MALT lymphomas, we divided the patients into two groups: those with high-grade lymphoma (n = 21) and those with low-grade lymphoma (n = 37). Common CT findings for the two groups were reviewed and compared., Results: Forty (69%) of the 58 patients showed at least one abnormality of the stomach on CT. Abnormalities included diffuse or segmental gastric wall thickening (66%, 38/58), lymphadenopathy (40%, 23/58), ulcer (22%, 13/58), and gastric mass (3%, 2/58). Eighteen (31%) of 58 patients were found to have no abnormality. The high-grade group had a higher incidence of abnormalities seen on CT than the low-grade group (100% vs 51%, respectively). Gastric wall thickening in the high-grade group was more diffuse (48% vs 8%) and severe (71% vs 14%; severe or moderate) than that seen in the low-grade group. Lymphadenopathy was visualized in 67% of the high-grade group and in 24% of the low-grade group. Gastric ulcer was found in 57% of the high-grade group and in only 5% of the low-grade group. The gastric mass formation was seen in only two patients in the high-grade group., Conclusion: The CT findings of gastric MALT lymphoma that the two groups had in common were gastric wall thickening and lymphadenopathy. Although our results pointed to no specific CT finding for differentiating high-grade from low-grade gastric MALT lymphomas, we found that the absence of abnormality on CT is highly predictive of low-grade MALT lymphoma.

Objective: The purpose of this study was to evaluate the radiographic and imaging findings of seven patients with polyarteritis nodosa involving the abdomen., Conclusion: Vasculitis should be considered when multiple abdominal organs have abnormal radiologic findings; however, angiography is necessary to specifically diagnose polyarteritis nodosa.

Objective: The purpose of this study was to assess the value of characteristic thin-section helical CT findings of acute diverticulitis involving the cecum and ascending colon in excluding colonic carcinoma., Materials and Methods: Thin-section helical CT scans (5-mm collimation) of 19 consecutive patients with proven diverticulitis and 21 consecutive patients with surgically proven carcinoma involving the cecum and ascending colon were reviewed retrospectively. Two radiologists independently analyzed these parameters: degree of pericolic infiltration, mesenteric fluid, vascular engorgement, arrowhead-shaped wall thickening, air-filled diverticula, inflamed diverticula, and preserved enhancement pattern of involved colonic wall. Inter-observer agreement was assessed with a kappa statistical analysis, and the features that most distinguished diverticulitis from colonic carcinoma were selected with a stepwise logistic-regression analysis., Results: The two CT findings of right-sided colonic diverticulitis that most distinguished it from colonic carcinoma were inflamed diverticula and the preservation of an enhancement pattern of the involved colonic wall. Excellent interobserver agreement (kappa > 0.60) was obtained for both findings. Inflamed diverticula (kappa = 0.80) had a mean sensitivity, specificity, and accuracy for diverticulitis of 86.8%, 92.9%, and 90.0%, respectively, in differentiating right-sided colonic diverticulitis from colonic carcinoma. Preserved wall enhancement pattern (kappa = 0.70) had a mean sensitivity, specificity, and accuracy of 89.5%, 95.3%, and 92.5%, respectively., Conclusion: On thin-section helical CT, an inflamed diverticula and a preserved enhancement pattern of the thickened colonic wall were the two most statistically significant CT findings of acute diverticulitis involving the cecum and ascending colon that distinguished diverticulitis from colonic carcinoma.

Objective: The preoperative diagnosis of a primary appendiceal tumor can be difficult because of its rarity and the paucity of material in the radiology literature. The purpose of this study was to describe CT findings in six patients with primary mucinous cystadenocarcinoma of the appendix., Conclusion: When CT reveals a cystic mass with enhancing wall nodularity in the expected area of the appendix, especially in older patients, the possibility of primary mucinous cystadenocarcinoma should be considered.

Objective: The purpose of our study was to describe CT and sonographic findings of foci of eosinophil-related hepatic necrosis and to correlate those findings with eosinophil counts in the peripheral blood., Materials and Methods: We retrospectively reviewed 17 helical CT and 16 sonographic examinations (including follow-up examinations) in 10 patients with pathologically proven foci of eosinophil-related necrosis. Underlying causes were anisakiasis (n = 2), malignant neoplasms (n = 3), hypereosinophilic syndrome (n = 3), and idiopathic (n = 2). CT and sonographic images were reviewed by consensus by three radiologists, with an emphasis on the morphology and distribution of foci. Imaging findings were correlated with eosinophil counts in the peripheral blood., Results: All foci of eosinophil-related necrosis were observed as focal hypoattenuating lesions on all phases of helical CT and as focal hypoechoic lesions on sonography. Foci varied in size and were round or oval. The number of these foci seemed to be in proportion to the percentage of eosinophils in the peripheral blood. Most foci showed interval regression on follow-up CT or sonography as peripheral blood eosinophil counts decreased., Conclusion: Foci of eosinophil-related necrosis cause focal hepatic lesions of varying size, shape, and number on helical CT and sonography. The number and extent of these foci were closely correlated to eosinophil counts in the peripheral blood.

Objective: The purpose of our study was to determine the value of the sliding sign on sonograms in evaluating direct pancreatic invasion of advanced gastric carcinoma., Subjects and Methods: Sonography was performed prospectively on 70 patients with pathologically proven advanced gastric carcinoma. Sonography was directed at the detection of motion between the gastric mass and the pancreas. When the gastric mass showed complete sliding motion against the pancreas or partial sliding motion with a preserved echogenic fat plane between the two organs on respiration or on extrinsic compression with a transducer (positive sliding sign), patients were considered to have no pancreatic invasion. When the gastric mass had no sliding motion against the pancreas or partial sliding motion with a disrupted echogenic fat plane between the two organs (negative sliding sign), patients were considered to have pancreatic invasion. After sonography, all patients underwent surgery and the results of sonography were compared with the findings at surgery and pathology., Results: Of the 70 patients, 17 had pancreatic invasion and 53 had no evidence of pancreatic invasion at surgery and pathology. The sliding sign on sonography yielded an 80% sensitivity, 96% specificity, and 90% accuracy for the diagnosis of pancreatic invasion., Conclusion: Application of the sliding sign on sonography was simple and highly accurate in the diagnosis of pancreatic invasion by advanced gastric carcinoma. The sliding sign may prove useful in the preoperative detection of pancreatic invasion by gastric carcinoma when CT has been inconclusive.

Objective: Our objective was to describe thin-section helical CT findings of acute diverticulitis of the cecum and ascending colon in 12 patients., Conclusion: Thin-section helical CT is able to reveal inflamed diverticula in acute diverticulitis of the cecum and ascending colon, which are diagnostic of this disease. Preservation of the enhancing pattern of the colonic wall was the most common helpful ancillary finding.

Objective: The purpose of this study was to evaluate the usefulness of color Doppler sonography in differentiating benign from malignant cervical lymphadenopathy., Materials and Methods: We used color Doppler sonography to evaluate 117 lymph nodes in 105 patients. The patients were pathologically and clinically confirmed to have benign reactive lymphadenitis (n = 28), tuberculosis (n = 17), lymphoma (n = 14), and metastasis (n = 46). The patterns of hilar vascularity, central nodal vascularity, and peripheral vascularity were assessed. The highest resistive index and pulsatility index in 116 lymph nodes were measured from spectral waveforms. Histologic findings of nodal vessels were analyzed in 14 nodes and compared with findings on color Doppler sonograms., Results: Thirty-two (94%) of 34 nodes with benign reactive disease showed normal patterns of nodal vascularity; central hilar vascularity, radial symmetric central vascularity, and no peripheral vascularity. At least one of six abnormal patterns of vascularity (eccentric or absent hilar vascularity; deformed radial, aberrant multifocal, or absent central vascularity; and peripheral vascularity) was observed in 98% (65/66) of nodes with malignant disease and in all tuberculous nodes. We established cutoff values of 0.8 for the resistive index and 1.5 for the pulsatility index that were 100% specific for malignancy. However, sensitivities for these cutoff values were 47% and 55%, respectively. Also, histologic examinations showed that most flow signals in nodes with malignant disease represented arterioles or veins in the septa between tumor nests or near the capsule., Conclusion: Unlike nodes with benign reactive disease, 98% of nodes with malignant disease and 100% of tuberculous nodes showed abnormal patterns of nodal vascularity. Also, high values for the resistive and pulsatility indexes were highly specific for malignant lymphadenopathy. Color Doppler sonography combined with analysis of spectral waveforms was useful in differentiating benign from malignant cervical lymphadenopathy.

Objective: The diagnosis of acute appendicitis in pregnant women often is difficult to make on the basis of clinical findings, and radiologic examination is limited because of the potentially hazardous effects of radiation. This study was done to assess the value of sonography in the diagnosis of acute appendicitis in pregnant women., Subjects and Methods: We obtained sonograms in 45 pregnant women with clinically suspected acute appendicitis. Our sonographic technique included graded-compression scanning. The left lateral decubitus position was used in the third trimester of gestation. The sonographic criterion for the diagnosis of acute appendicitis was visualization of an incompressible appendix with a maximal diameter greater than 7 mm. We correlated the sonographic findings with the surgical findings in 22 cases and with the results of clinical follow-up in 23 cases., Results: Sonography could not be used to make the diagnosis in three (7%) of 45 patients because the size of the gravid uterus prevented use of the graded-compression technique. These three patients were in the third trimester of pregnancy (greater than 35 weeks' gestation). Sonographic findings were used as a basis for diagnosis in 42 cases. Acute appendicitis was diagnosed on the basis of sonograms in 16 patients, and in all but one of these patients, acute appendicitis was confirmed by surgical and pathologic findings. In the 42 cases in which the imaging findings indicated the diagnosis, the overall sensitivity of sonography was 100%, the specificity was 96%, and the accuracy was 98%., Conclusion: Our experience suggests that graded-compression sonography is a valuable procedure for detecting acute appendicitis in pregnant women despite technical difficulty in performing it during the third trimester of pregnancy.