Kyoung Doo Song

Utility of iodine overlay technique and virtual unenhanced images for the characterization of renal masses by dual-energy CT.

OBJECTIVEnThe objective of our study was to assess the utility of dual-energy CT for characterizing renal masses using iodine overlay techniques and virtual unenhanced images and to measure the potential radiation dose reduction for two-phase kidney CT compared with a standard three-phase protocol.nnnMATERIALS AND METHODSnSixty patients with suspected renal masses underwent dual-energy CT including true unenhanced, dual-energy corticomedullary, and dual-energy late nephrographic phase imaging. Iodine overlay and virtual unenhanced images were derived from the corticomedullary and late nephrographic phases, respectively. The CT numbers of renal masses were calculated using the iodine overlay images superimposed on the virtual unenhanced images. The overall imaging quality of the true unenhanced images and of the virtual unenhanced images was also evaluated. The effective radiation doses for dual-energy CT and for true unenhanced imaging were calculated.nnnRESULTSnFor overlay or enhancement values on iodine overlay images, 36 simple cysts and 10 hemorrhagic cysts had an attenuation value of less than 20 HU, whereas 21 renal cell carcinomas showed an attenuation value of 20 HU or greater. Eleven angiomyolipomas contained macroscopic fat tissue. All renal masses were accurately classified on the basis of dual-energy CT. The imaging quality of the virtual unenhanced images from the corticomedullary and late nephrographic phases was inferior to the image quality of the true unenhanced images (p < 0.01). The mean effective doses for the three-phase protocol and for true unenhanced images were 12.6 and 2.4 mSv, respectively.nnnCONCLUSIONnOur results show that dual-energy CT using iodine overlay techniques and virtual unenhanced images may be useful for characterizing renal masses.

Small Hepatocellular Carcinoma: Radiofrequency Ablation versus Nonanatomic Resection—Propensity Score Analyses of Long-term Outcomes

PURPOSEnTo compare radiofrequency (RF) ablation with nonanatomic resection (NAR) as first-line treatment in patients with a single Barcelona Clinic Liver Cancer (BCLC) stage 0 or A hepatocellular carcinoma (HCC) and to evaluate the long-term outcomes of both therapies.nnnMATERIALS AND METHODSnThis retrospective study was approved by the institutional review board. The requirement for informed consent was waived. Data were reviewed from 580 patients with HCCs measuring 3 cm or smaller (BCLC stage 0 or A) who underwent ultrasonographically (US) guided percutaneous RF ablation (n = 438) or NAR (n = 142) as a first-line treatment. Local tumor progression, intrahepatic distant recurrence, disease-free survival, and overall survival rates were analyzed by using propensity score matching to compare therapeutic efficacy. In addition, major complications and length of postoperative hospital stay were compared.nnnRESULTSnBefore propensity score matching (n = 580), the 5-year cumulative rates of local tumor progression for RF ablation and NAR (20.9% vs 12.7%, respectively; P = .093) and overall survival rates (85.5% vs 90.9%, respectively; P = .194) were comparable, while the 5-year cumulative intrahepatic distant recurrence rates (62.7% vs 36.6%, respectively; P < .001) and disease-free survival rates (31.7% vs 61.1%, respectively; P < .001) in the NAR group were significantly better than those in the RF ablation group. After matching (n = 198), there were no significant differences in therapeutic outcomes between the RF ablation and NAR groups, including 5-year cumulative intrahepatic distant recurrence (47.0% vs 40.2%, respectively; P = .240) and disease-free survival rates (48.9% vs 54.4%, respectively; P = .201). RF ablation was superior to NAR for major complication rates and length of postoperative hospital stay (P < .001).nnnCONCLUSIONnIn patients with one BCLC stage 0 or A (≤ 3 cm) HCC who received RF ablation or NAR as first-line treatment, there were no significant differences in long-term therapeutic outcomes; however, RF ablation was associated with fewer major complications and a shorter hospital stay after treatment.

Fusion Imaging–Guided Radiofrequency Ablation for Hepatocellular Carcinomas Not Visible on Conventional Ultrasound

OBJECTIVEnThe 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.nnnMATERIALS AND METHODSnPlanning 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.nnnRESULTSnWhen 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.nnnCONCLUSIONnFusion 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.

Radiofrequency ablation of very-early-stage hepatocellular carcinoma inconspicuous on fusion imaging with B-mode US: value of fusion imaging with contrast-enhanced US

Background/Aims To determine the value of fusion imaging with contrast-enhanced ultrasonography (CEUS) and computed tomography (CT)/magnetic resonance (MR) images for percutaneous radiofrequency ablation (RFA) of very-early-stage hepatocellular carcinomas (HCCs) that are inconspicuous on fusion imaging with B-mode ultrasound (US) and CT/MR images. Methods This retrospective study was approved by our institutional review board and the requirement for informed consent was waived. Fusion imaging with CEUS using Sonazoid contrast agent and CT/MR imaging was performed on HCCs (<2 cm) that were inconspicuous on fusion imaging with B-mode US. We evaluated the number of cases that became conspicuous on fusion imaging with CEUS. Percutaneous RFA was performed under the guidance of fusion imaging with CEUS. Technical success and major complication rates were assessed. Results In total, 30 patients with 30 HCCs (mean, 1.2 cm; range, 0.6-1.7 cm) were included, among which 25 (83.3%) became conspicuous on fusion imaging with CEUS at the time of the planning US and/or RFA procedure. Of those 25 HCCs, RFA was considered feasible for 23 (92.0%), which were thus treated. The technical success and major complication rates were 91.3% (21/23) and 4.3% (1/23), respectively. Conclusions Fusion imaging with CEUS and CT/MR imaging is highly effective for percutaneous RFA of very-early-stage HCCs inconspicuous on fusion imaging with B-mode US and CT/MR imaging.

Indirect MR Arthrographic Findings of Adhesive Capsulitis

OBJECTIVEnThe objective of our study was to compare the indirect MR arthrographic findings of patients with adhesive capsulitis and patients without adhesive capsulitis.nnnMATERIALS AND METHODSnIndirect MR arthrograms of 35 patients (21 women, 14 men; mean age, 50.1 years) diagnosed with adhesive capsulitis clinically were compared with indirect MR arthrograms of 45 patients (23 women, 22 men; mean age, 48.9 years) without adhesive capsulitis. Joint capsule thickness in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were, respectively, evaluated on coronal T2-weighted images and coronal and sagittal fat-suppressed enhanced T1-weighted images by two radiologists independently. Reliability was studied using the intraclass correlation coefficient (ICC). Receiver operating characteristic (ROC) curves were compared.nnnRESULTSnPatients with adhesive capsulitis had significantly thickened joint capsules in the axillary recess and a thickened enhancing portion in the axillary recess and in the rotator interval. The difference in the thicknesses of the enhancing portion in the axillary recess and in the rotator interval were significantly greater than the difference in joint capsule thicknesses in the axillary recess between the adhesive capsulitis group and the control group (p < 0.001). Interobserver reliability was good for all three indexes (ICC ≥ 0.80). The area under the ROC curve for the thickness of the joint capsule in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were 0.797, 0.861, and 0.847, respectively.nnnCONCLUSIONnAn abundance of enhancing tissue in the rotator interval and thickening and enhancement of the axillary recess are signs suggestive of adhesive capsulitis on indirect MR arthrography.

Pulmonary Cryptococcosis: Imaging Findings in 23 Non-AIDS Patients

Objective We aimed to review the patterns of lung abnormalities of pulmonary cryptococcosis on CT images, position emission tomography (PET) findings of the disease, and the response of lung abnormalities to the therapies in non-AIDS patients. Materials and Methods We evaluated the initial CT (n = 23) and 18F-fluorodeoxyglucose (FDG) PET (n = 10), and follow-up (n = 23) imaging findings of pulmonary cryptococcosis in 23 non-AIDS patients. Lung lesions were classified into five patterns at CT: single nodular, multiple clustered nodular, multiple scattered nodular, mass-like, and bronchopneumonic patterns. The CT pattern analyses, PET findings, and therapeutic responses were recorded. Results A clustered nodular pattern was the most prevalent and was observed in 10 (43%) patients. This pattern was followed by solitary pulmonary nodular (n = 4, 17%), scattered nodular (n = 3, 13%), bronchopneumonic (n = 2, 9%), and single mass (n = 1, 4%) patterns. On PET scans, six (60%) of 10 patients showed higher FDG uptake and four (40%) demonstrated lower FDG uptake than the mediastinal blood pool. With specific treatment of the disease, a complete clearance of lung abnormalities was noted in 15 patients, whereas a partial response was noted in seven patients. In one patient where treatment was not performed, the disease showed progression. Conclusion Pulmonary cryptococcosis most commonly appears as clustered nodules and is a slowly progressive and slowly resolving pulmonary infection. In two-thirds of patients, lung lesions show high FDG uptake, thus simulating a possible malignant condition.

Repeated Hepatic Resection versus Radiofrequency Ablation for Recurrent Hepatocellular Carcinoma after Hepatic Resection: A Propensity Score Matching Study

PURPOSEnTo compare the long-term outcomes of repeated hepatic resection and radiofrequency (RF) ablation for recurrent hepatocellular carcinoma (HCC) by using propensity score matching.nnnMATERIALS AND METHODSnThis retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Thirty-nine patients who underwent repeated hepatic resection and 178 who underwent RF ablation for recurrent HCC (mean tumor size ± standard deviation, 1.8 cm ± 0.7) between November 1994 and December 2012 were included in the study. Patients ranged in age from 24 to 85 years (mean, 54.9 years). Men ranged in age from 25 to 85 years (mean, 54.8 years), and women ranged in age from 24 to 76 years (mean, 55.4 years). A 1:2 repeated hepatic resection group-RF ablation group matching was done by using propensity score matching. The overall survival (OS) and disease-free survival (DFS) were compared before and after propensity score matching. Complications were assessed.nnnRESULTSnBefore matching, OS rates at 1, 3, 5, and 8 years were 88.8%, 88.8%, 83.9%, and 56.3%, respectively, with repeated hepatic resection and 98.9%, 82.5%, 71.0%, and 58.3% for RF ablation. DFS rates at 1, 3, and 5 years were 66.1%, 48.5%, and 43.1% for repeated hepatic resection and 70.1%, 40.8%, and 30.0% for RF ablation. After matching, the OS rates at 1, 3, 5, and 8 years were 98.7%, 85.7%, 72.1%, and 68.6%, respectively, and the DFS rates at 1, 3, and 5 years were 71.8%, 45.1%, and 39.4% in the RF ablation group (n = 78). Neither the OS nor DFS rate was significantly different between the two groups before matching (P = .686 and P = .461) and after matching (P = .834 and P = .960). The postoperative mortality rate was 2.6% in the repeated hepatic resection group and 0% in the RF ablation group.nnnCONCLUSIONnThe long-term OS and DFS were not significantly different between repeated hepatic resection and RF ablation for patients with recurrent HCC after hepatic resection.

The MR imaging diagnosis of liver diseases using gadoxetic acid: Emphasis on hepatobiliary phase

Hepatocyte specific contrast agents including gadoxetic acid and gadobenate dimeglumine are very useful to diagnose various benign and malignant focal hepatic lesions and even helpful to estimate hepatic functional reservoir. The far delayed phase image referred to as the hepatobiliary phase makes the sensitivity of detection for malignant focal hepatic lesions increased, but specificity of malignant diseases, including hepatocellular carcinoma, metastasis and cholangiocarcinoma, characterization remained to be undetermined.

Mistargeting after Fusion Imaging–Guided Percutaneous Radiofrequency Ablation of Hepatocellular Carcinomas

PURPOSEnTo evaluate the incidence and causes of mistargeting after fusion imaging-guided percutaneous radiofrequency (RF) ablation of hepatocellular carcinomas (HCCs).nnnMATERIALS AND METHODSnBetween September 2011 and March 2013, 955 HCCs in 732 patients were treated with percutaneous RF ablation. Among them, ablation of 551 HCCs was accomplished under fusion imaging guidance, and seven mistargetings were noted in seven patients (male-to-female ratio = 6:1; mean age, 60.1 y; range, 47-73 y). The incidence of mistargeting and the cause of liver disease in the patients with mistargeting were evaluated. The causes of mistargeting were assessed according to the following classification: small size of HCC, subcapsular location, subphrenic location, confusion with pseudolesions, poor conspicuity of HCC, poor sonographic window, and poor electrode path.nnnRESULTSnThe incidence of mistargeting after fusion imaging-guided RF ablation was 1.3% (7 of 551). All patients with mistargeting were hepatitis B virus carriers. The most common cause of mistargeting was the small size of HCC (100%; 7 of 7), followed by confusion with surrounding pseudolesions (85.7%; 6 of 7), subcapsular (71.4%; 5 of 7) and subphrenic locations (71.4%; 5 of 7), poor conspicuity of the HCC (71.4%; 6 of 7), poor sonographic window (28.6%; 2 of 7), and poor electrode path (28.6%; 2 of 7).nnnCONCLUSIONSnThe incidence of mistargeting after fusion imaging-guided RF ablation was 1.3%. The most common cause of mistargeting was the small size of HCC, followed by confusion with surrounding pseudolesions, subcapsular and subphrenic locations, and poor conspicuity of the HCC.

Mass-forming Intrahepatic Cholangiocarcinoma: Diffusion-weighted Imaging as a Preoperative Prognostic Marker

Purpose To assess the value of diffusion-weighted (DW) imaging as a prognostic marker in preoperative evaluation of patients with mass-forming intrahepatic cholangiocarcinoma (ICC). Materials and Methods This retrospective study was approved by the institutional review board, and the informed consent requirement was waived. A total of 91 patients who underwent hepatic resection and DW imaging for mass-forming ICC were included. Two radiologists evaluated the degree of diffusion restriction of the tumors by using qualitative (visual) interpretation combined with quantitative analysis by volumetric evaluation of the whole tumor on DW images. Patients were classified into two groups: those in whom less than one-third of the tumor showed diffusion restriction (group 1) and those in whom more than one-third of the tumor showed diffusion restriction (group 2). Imaging findings in tumors were compared with pathology findings. Disease-free and overall survival rates were compared between the two groups by using the Kaplan-Meier method with the log-rank test. Results There were 43 patients in group 1 and 48 patients in group 2. The 1- and 3-year disease-free survival rates were 30% and 16%, respectively, in group 1 and 75% and 64%, respectively, in group 2 (P < .001). The 1- and 3-year overall survival rates were 77% and 26%, respectively, in group 1 and 92% and 67%, respectively, in group 2 (P = .001). Multivariate analysis revealed that diffusion restriction (P = .024), differentiation (P = .030), and intrahepatic metastasis (P = .001) were independent prognostic factors for overall survival. Conclusion The degree of diffusion restriction on DW images may be a prognostic marker in preoperative evaluation of patients with mass-forming ICC. (©) RSNA, 2016 Online supplemental material is available for this article.