Hyo Keun Lim

Gadoxetic Acid–Enhanced MRI Versus Triple-Phase MDCT for the Preoperative Detection of Hepatocellular Carcinoma

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.

Ten-year outcomes of percutaneous radiofrequency ablation as first-line therapy of early hepatocellular carcinoma: Analysis of prognostic factors

BACKGROUND & AIMS The aim was to assess 10-year outcomes of radiofrequency ablation as a first-line therapy of early-stage hepatocellular carcinoma with an analysis of prognostic factors. METHODS From April 1999 to April 2011, 1305 patients (male:female=993:312; mean age, 58.4 years) with 1502 early-stage hepatocellular carcinomas (mean size, 2.2 cm) were treated with percutaneous radiofrequency ablation as a first-line option. Follow-up period ranged from 0.4 to 146.6 months (median, 33.4 months). We assessed the 10-year follow-up results of recurrences and survival with the analyses of prognostic factors. RESULTS Recurrences occurred in 795 patients (1-17 times), which were managed with various therapeutic modalities. The cumulative local tumor progression rates were 27.0% and 36.9% at 5 and 10 years, respectively, for which the only significant risk factor was large tumor size (B=0.584, p=0.001). Cumulative intrahepatic distant and extrahepatic recurrence rates were 73.1% and 88.5%, and 19.1% and 38.2% at 5 and 10 years, respectively. Corresponding overall survival rates were 59.7% and 32.3%, respectively. Poor survival was associated with old age (B=0.043, p=0.010), Child-Pugh class B (B=-1.054, p<0.001), absence of antiviral therapy during follow-up (B=-0.699, p=0.034), and presence of extrahepatic recurrence (B=0.971, p=0.007). CONCLUSIONS Ten-year survival outcomes after percutaneous radiofrequency ablation as a first-line therapy of hepatocellular carcinoma were excellent despite frequent tumor recurrences. Overall survival was influenced by age, Child-Pugh class, antiviral therapy, or extrahepatic recurrence.

The Minimal Ablative Margin of Radiofrequency Ablation of Hepatocellular Carcinoma (> 2 and < 5 cm) Needed to Prevent Local Tumor Progression: 3D Quantitative Assessment Using CT Image Fusion

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.

Percutaneous Radiofrequency Ablation with Artificial Ascites for Hepatocellular Carcinoma in the Hepatic Dome: Initial Experience

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.

Spectrum of CT Findings after Radiofrequency Ablation of Hepatic Tumors

Image-guided radiofrequency (RF) ablation has been used to treat both resectable and nonresectable hepatic tumors. A precise imaging assessment of the therapeutic response and of any complications is mandatory after ablation. Contrast material-enhanced ultrasonography, computed tomography (CT), and magnetic resonance imaging all may be useful for this assessment. At most institutions, a three-phase contrast-enhanced CT examination is performed immediately or within 1 month after RF ablation to assess the technical success of treatment. If ablation was technically successful, three-phase CT may be repeated at 3-month intervals for evaluation of tumor recurrence. The typical CT finding in the zone subjected to RF ablation is an area of low attenuation that encompasses the tumor and an ablative margin. However, the appearance of the ablative zone may vary greatly, depending on the success of treatment and the time elapsed after the procedure. Ringlike enhancement representing benign reactive hyperemia around the ablation zone, central high-attenuation areas representing greater cellular disruption, and tiny air bubbles frequently are seen at immediate follow-up CT but usually have disappeared by the first or second follow-up examination. The successfully ablated zone gradually involutes. The appearance of the zone differs when residual tumor tissue or local tumor progression is present. Immediate or delayed complications also may be seen at follow-up CT. Radiologists must be familiar with both typical and atypical CT findings and their clinical significance. (c) RSNA, 2008.

Radiological Spectrum of Intraductal Papillary Tumors of the Bile Ducts

Papillary tumor of the bile duct is characterized by the presence of an intraductal tumor with a papillary surface comprising innumerable frondlike infoldings of proliferated columnar epithelial cells surrounding slender fibrovascular stalks. There may be multiple tumors along the bile ducts (papillomatosis or papillary carcinomatosis), which are dilated due to obstruction by a tumor per se, by sloughed tumor debris, or by excessive mucin. Radiologically, the biliary tree is diffusely dilated, either in a lobar or segmental fashion, or aneurysmally, depending on the location of the tumor, the debris, and the amount of mucin production. A tumor can be depicted by imaging as an intraductal mass with a thickened and irregular bile duct wall. Sloughed tumor debris and mucin plugs should be differentiated from bile duct stones. Cystically or aneurysmally, dilated bile ducts in mucin-hypersecreting variants (intraductal papillary mucinous tumors) should be differentiated from cystadenoma, cystadenocarcinoma and liver abscess.

Percutaneous Radiofrequency Ablation of Hepatocellular Carcinoma: Fusion Imaging Guidance for Management of Lesions With Poor Conspicuity at Conventional Sonography

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.

Preoperative staging of rectal cancer: accuracy of 3-Tesla magnetic resonance imaging

The purpose of this study was to evaluate the accuracy of 3-Tesla magnetic resonance imaging (MRI) for the preoperative staging of rectal cancer. Thirty-five patients with a primary rectal cancer who underwent preoperative 3-T MRI using a phased-array coil and had a surgical resection were enrolled in the study group. Preoperatively, three experienced radiologists independently assessed the T and N staging. A confidence level scoring system was used to determine if there was any perirectal invasion, and receiver operating characteristic (ROC) curves were generated. The interobserver agreement was estimated using κ statistics. The overall accuracy rate of T staging for rectal cancer was 92%. The diagnostic accuracy was 97% for T1, 89% for T2 and 91% for T3, respectively. The predictive accuracy for perirectal invasion by the three observers was high (Az>0.92). The interobserver agreement for T staging was moderate to substantial. The overall sensitivity, specificity, and accuracy for the detection of mesorectal nodal metastases were 80%, 98%, and 95%, respectively. In conclusion, preoperative 3-T MRI using a phase-array coil accurately indicates the depth of tumor invasion for rectal cancer with a low variability.

Detecting recurrence of gastric cancer: the value of FDG PET/CT

PurposeIn order to assess the diagnostic performance of Positron emission tomography/Computed tomography (PET/CT) for detecting recurrence in gastric cancer patients with clinical or radiologic suspicion of recurrence after surgical resection.Materials and methodsOver a 4-year period, 105 post-operative patients with gastric cancer, who underwent PET/CT due to clinical or radiologic suspicion of recurrence during follow-up, were collected after confirming their PET/CT findings. The number and site of positive FDG uptake were retrospectively analyzed, and were correlated with the final diagnosis, by calculating the diagnostic values and assessing the causes of misdiagnosis.ResultsOf all 105 patients, 75 patients were confirmed to have true recurrence with 108 recurrence sites. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for diagnosing true recurrence on a per-person basis were 75%, 77%, 89%, 55%, and 75%, respectively. On a per-lesion basis, 75 (69%) of 108 true recurrences showed positive FDG uptake, while 75 (89%) of 84 positive FDG uptake was confirmed to have true recurrence.ConclusionPET/CT was relatively accurate in detecting recurrence in post-operative patients with gastric cancer. Moreover, PET/CT might be helpful in confirming the presence of recurrence particularly in patients who were highly suspicious of recurrence, because of its high positive predictability.

Percutaneous Radiofrequency Ablation for the Hepatocellular Carcinoma Abutting the Diaphragm: Assessment of Safety and Therapeutic Efficacy

Objective To assess the safety and therapeutic efficacy of a percutaneous radiofrequency (RF) ablation for the hepatocellular carcinoma (HCC) abutting the diaphragm. Materials and Methods We retrospectively assessed 80 patients who underwent a percutaneous RF ablation for a single nodular (< 4 cm) HCC over the last four years. Each patient underwent an ultrasound-guided RF ablation using internally cooled electrodes for the first-line treatment. We divided patients into two subgroups based on whether the index tumor was abutting (less than 5 mm) the diaphragm or not: group A (abutting; n = 31) versus group B (non-abutting; n = 49). We compared the two subgroups for complications and therapeutic efficacy using image and the review of medical records. The statistical assessment included an independent t-test, Fishers exact test, and chi-square test. Results The assessment of the diaphragmatic swelling at CT immediately following the procedure was more severe in group A than group B (mean thickness change:1.44 vs. 0.46 mm, p = 0.00). Further, right shoulder pain was more common in group A than B (p = 0.01). Although minor complications (hemothorax 1 case, pleural effusion 1 case) were noted only in group A, no major thoracic complication occurred in either group. The technical success rate was lower in group A than group B (84% vs. 98%, p = 0.03). As well, the primary and secondary technique effectiveness rates in group A and group B were 90% versus 98% (p = 0.29) and 79% versus 91% (p = 0.25), respectively. The local tumor progression rate was higher in group A than in group B (29% vs. 6%, p = 0.02). Conclusion We found that the percutaneous RF ablation for the HCC abutting the diaphragm is a safe procedure without major complications. However, it is less effective with regard to technical success and local tumor control.