Utility of diffusion-weighted imaging in association with pathologic upgrading in biopsy-proven grade I endometrial cancer.

BACKGROUND: Prediction of pathologic upgrading is clinically meaningful to identify the optimal candidate of fertility-preserving hormonal treatment in the young patients with biopsy-proven grade I endometrial cancer. PURPOSE: To investigate the utility of diffusion-weighted imaging (DWI) in association with pathologic upgrading in endometrial cancer. STUDY TYPE: Retrospective. SUBJECTS: Preoperative MRI datasets of 221 patients with grade I endometrial cancer on endometrial biopsy (n = 146), dilatation and curettage (n = 66), or either (n = 9). FIELD STRENGTH/SEQUENCE: 3.0T, including T2 -weighted imaging, DWI with a b-value of 1000 s/mm2 , and dynamic contrast enhanced imaging. ASSESSMENT: The tumor size was determined as the longest diameter of the lesion. The minimum apparent diffusion coefficient (ADCmin ) was calculated using histogram analysis of the entire tumor. STATISTICAL TESTS: Mann-Whitney U-test, Pearson's chi-square test, Fisher's exact test, intraclass correlation coefficient (ICC) analysis, receiver operating characteristic (ROC) curve analysis, univariate and multivariate logistic regression analysis. RESULTS: Pathologic upgrading was identified in 42 patients (19.0%). Patients with pathologic upgrading had larger tumors and showed lower ADCmin values than those without pathologic upgrading (both P < 0.001). The area under the ROC curve of ADCmin and tumor size was 0.812 and 0.758, respectively. On multivariate analysis, tumor ADCmin ≤0.600 × 10-3 mm2 /s (odds ratio [OR], 11.8; P < 0.001) and tumor size on MRI >3 cm (OR, 3.24; P = 0.009) were independently associated with pathologic upgrading. Upgrading occurred in 23 of 31 patients (74.2%) with ADCmin ≤0.600 × 10-3 mm2 /s and tumor size >3 cm, and in 7 of 114 patients (6.1%) with ADCmin >0.600 × 10-3 mm2 /s and tumor size ≤3 cm. DATA CONCLUSION: Tumor ADC and tumor size on MRI may be useful parameters in association with pathologic upgrading in biopsy-proven grade I endometrial cancer. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:117-123.

Sonography of the first metatarsophalangeal joint and sonographically guided intraarticular injection of corticosteroid in acute gout attack.

OBJECTIVE: The aims of this study were to identify the characteristic ultrasound (US) findings of the first metatarsophalangeal joint (MTPJ1) in acute gout attack and to evaluate the efficacy and safety of US-guided intraarticular corticosteroid injection of the MTPJ1. METHODS: We enrolled 21 patients with acute gout attack involving the MTPJ1 unilaterally. US evaluation of each affected MTPJ1 was compared with radiographic features. US-guided intraarticular corticosteroid (0.5 ml [20 mg] of triamcinolone mixed with 0.5 ml of 2% lidocaine) was injected into the affected MTPJ1s. Pain, general disability, and walking disability were assessed at baseline, 24 hours, 48 hours, and 7 days after injection with visual analog scales. RESULTS: The characteristic US findings of MTPJ1 were erosion, joint effusion, synovial hypertrophy, tophus-like lesion, double contour, hyperechoic spots, and increased power Doppler signal in acute gout attack. US was more sensitive than conventional radiograph in detecting erosion and tophus-like lesion. The reductions of mean visual analog scale scores in pain, general disability, and walking disability were 48 mm (SD, 27), 35 mm (SD, 26) and 39 mm (SD, 26), respectively, 48 hours after US-guided intraarticular corticosteroid injection. There were no adverse events. CONCLUSIONS: US is a sensitive tool to evaluate joint abnormality of the MTPJ1 in acute gout attack and US-guided intraarticular corticosteroid injection to this joint is effective and safe.

Subtype differentiation of renal cell carcinoma using diffusion-weighted and blood oxygenation level-dependent MRI.

OBJECTIVE: The purpose of this article is to evaluate the utility of diffusion-weighted imaging (DWI) and blood oxygenation level-dependent (BOLD) MRI for characterizing renal cell carcinoma (RCC) subtypes at 3 T. MATERIALS AND METHODS: Seventy-seven patients underwent 3-T DWI and BOLD MRI. Apparent diffusion coefficient (ADC; × 10(-3) mm(2)/s) and rate of spin dephasing (R2*, which equals 1 / T2* relaxation time, or 1/s) values were measured in the three RCC subtypes and normal renal parenchyma, and the results were compared. Statistical analyses were performed using analysis of variance, Student t test, and ROC curve analysis. RESULTS: Clear cell RCCs showed statistically significantly greater ADC values (1.81 × 10(-3) mm(2)/s) than did papillary (1.29 × 10(-3) mm(2)/s) and chromophobe (1.55 × 10(-3) mm(2)/s) RCCs (p < 0.01); however, no statistically significant differences between papillary and chromophobe RCCs were observed (p = 0.26). Chromophobe RCCs showed the greatest mean R2* (33.6 1/s) of the three subtypes (p < 0.01); however, no statistically significant differences between clear cell RCCs and papillary RCCs were seen (p = 0.48). Low-grade clear cell RCCs showed statistically significantly higher ADC value (1.97 × 10(-3) mm(2)/s) than did high-grade clear cell RCCs (1.66 × 10(-3) mm(2)/s; p = 0.021). For differentiating clear cell RCCs from non-clear cell RCCs, the AUCs of ADC and R2* values were 0.756 × 10(-3) mm(2)/s and 0.607 (1/s), respectively (p = 0.047): cutoff values of ADC (1.4 × 10(-3) mm(2)/s) and R2* (26.3 1/s) resulted in sensitivities and specificities of 85% and 73%, and 86% and 47%, respectively. CONCLUSION: For characterizing RCC subtypes, DWI and BOLD MRI at 3 T may be useful, but the current technique of BOLD MRI seems to have a limited diagnostic accuracy.

Prostate cancer: role of pretreatment multiparametric 3-T MRI in predicting biochemical recurrence after radical prostatectomy.

OBJECTIVE: The purpose of this study is to retrospectively investigate whether pretreatment multiparametric MRI findings can predict biochemical recurrence in patients who underwent radical prostatectomy (RP) for localized prostate cancer. MATERIALS AND METHODS: In this study, 282 patients with biopsy-proven prostate cancer who received RP underwent pretreatment MRI using a phased-array coil at 3 T, including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI). MRI variables included apparent tumor presence on combined imaging sequences, extracapsular extension, and tumor size on DWI or DCE-MRI. Clinical variables included baseline prostate-specific antigen (PSA) level, clinical stage, and Gleason score at biopsy. The relationship between clinical and imaging variables and biochemical recurrence was evaluated using Cox regression analysis. RESULTS: After a median follow-up of 26 months, biochemical recurrence developed in 61 patients (22%). Univariate analysis revealed that all the imaging and clinical variables were significantly associated with biochemical recurrence (p < 0.01). On multivariate analysis, however, baseline PSA level (p = 0.002), Gleason score at biopsy (p = 0.024), and apparent tumor presence on combined T2WI, DWI, and DCE-MRI (p = 0.047) were the only significant independent predictors of biochemical recurrence. Of the independent predictors, apparent tumor presence on combined T2WI, DWI, and DCE-MRI showed the highest hazard ratio (2.38) compared with baseline PSA level (hazard ratio, 1.05) and Gleason score at biopsy (hazard ratio, 1.34). CONCLUSION: The apparent tumor presence on combined T2WI, DWI, and DCE-MRI of pretreatment MRI is an independent predictor of biochemical recurrence after RP. This finding may be used to construct a predictive model for biochemical recurrence after surgery.

Radiofrequency Ablation of Papillary Thyroid Microcarcinoma: A 10-Year Follow-Up Study.

Purpose: To investigate the efficacy and safety of radiofrequency ablation (RFA) for papillary thyroid microcarcinoma (PTMC) after > 10 years of follow-up. Materials and Methods: This study included five patients who underwent RFA to treat PTMCs (five lesions, mean diameter 0.5 cm, range 0.4-0.7 cm) between November 2006 and December 2009. The inclusion criteria were histopathologically confirmed PTMCs, a single PTMC lesion without extrathyroidal extension, no metastasis, and ineligibility or refusal to undergo surgery. RFA was performed by a single radiologist using a radiofrequency generator and an internally cooled electrode. We retrospectively analyzed the procedure-induced complications, serial changes in ablated tumors, recurrence, and local as well as lymph node metastasis based on data obtained from medical records and radiological images. Results: The mean follow-up period was 130.6 months (range 121-159 months). Three patients underwent a single RFA session, and two patients underwent two RFA sessions. We observed no procedure-induced complications. Three tumors completely disappeared after ablation, and ablation of the other two tumors resulted in the formation of a small scar that showed long-term stability (mean duration 16.8 months, range 12-27 months). At the last follow-up, no patient showed recurrence or lymph node metastasis, and serum thyroglobulin levels were within normal limits in all patients. Conclusion: RFA may be effective and safe to treat low-risk PTMC in patients who refuse or are ineligible for surgery.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations.

Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1-2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.

Follow-Up of Blebs and Bullae in Pilots 40 Years and Older Using CT.

BACKGROUND: Preventive treatment for incidentally detected blebs or bullae is required for fast jet pilots, but their aeromedical risk is not clearly proven.METHODS: This is a retrospective study and includes 46 pilots 40 yr and older with incidentally detected emphysema-like changes (ELCs) comprising blebs or bullae in low-dose chest CT (LDCT) during health screening. Two radiologists retrospectively reviewed imaging features. Statistical analysis was done using independent t-tests and bivariate analysis.RESULTS: Among 46 pilots, 39 pilots flew fast jet aircraft and 7 pilots flew nonfast jet aircraft. The mean follow-up period was 1531 d and the LDCT follow-up interval mean period was 424.4 d. There was no evidence of rupture in incidentally detected ELCs during the follow-up period. The mean size of the ELCs was 19.15 mm. There were five cases showing changes in size. There was a statistically significant correlation between the size of ELCs and height. There were no statistically significant differences in the size or number of ELCs relating to smoking status or aircraft type, and there were no statistically significant correlations between the size or number of ELCs and multiple factors, including smoking quantity, flight time, age, BMI, and weight.CONCLUSION: This study demonstrates the aeromedical safety of incidentally detected ELCs in pilots 40 yr and older without underlying lung disease. The results indicate no need for recommending preventive treatment for ELCs in pilots 40 yr and older, even those flying fast jet aircraft, as a requisite to continue their flight duties. KEYWORDS: bleb, bulla, pilot, CT.Bang S, Yang S, Cho SW, Kim DH, Kang H. Follow-up of blebs and bullae in pilots 40 years and older using CT. Aerosp Med Hum Perform. 2019; 90(10):867-871.

Neural correlates of affective processing in response to sad and angry facial stimuli in patients with major depressive disorder.

Mood abnormalities related to major depressive disorder (MDD) seem to result from disturbances in pathways connecting the fronto-limbic and subcortical, both regions known to be involved in the processing of emotional information. Using functional magnetic resonance imaging (fMRI), we measured neural responses to viewing images of sad, angry and neutral faces in 21 patients with MDD and 15 healthy controls. When shown pictures of sad faces, patients with MDD relative controls showed decreased activations bilaterally in the dorsolateral prefrontal cortex, inferior orbitofrontal cortex (OFC), medial OFC, caudate, and hippocampus. We also found significant group differences under the angry face condition, bilaterally, in the inferior OFC and medial OFC areas. Our findings indicate that decreased activations in the fronto-limbic and subcortical regions in response to affectively negative stimuli may be associated with pathophysiology of MDD.

[Pancreatic Neuroendocrine Tumor Presenting as Acute Pancreatitis].

We report a case of acute pancreatitis secondary to pancreatic neuroendocrine tumor. A 46-year old man presented with upper abdominal pain. The serum amylase and lipase were elevated. Abdominal computed tomography (CT) and magnetic resonance cholangiopancreatography revealed a 1.7 cm sized mass at the pancreas body with a dilatation of the upstream pancreatic duct and mild infiltrations of peripancreatic fat. An endoscopic ultrasound-guided fine needle biopsy was performed for the pancreatic mass, but only necrotic tissue was observed on the pathologic examination. A chest and neck CT scan revealed anterior mediastinal, paratracheal, and cervical lymph node enlargement, which were indicative of metastasis. An ultrasound-guided core needle biopsy was performed for the enlarged neck lymph node, and pathologic examination revealed a metastatic poorly differentiated carcinoma. Immunohistochemical analysis showed positive staining for synaptophysin, chromogranin A, and CD 56, indicative of a neuroendocrine carcinoma.

Percutaneous cholecystostomy for biliary decompression in patients with cholangitis and pancreatitis.

Objective This study was performed to assess the effectiveness and safety of percutaneous cholecystostomy (PC) for biliary decompression. Methods We retrospectively analyzed our institution's PC database from March 2015 to August 2017 and selected patients with biliary obstruction. The primary outcomes were the technical and clinical success rates. As secondary outcomes, adverse events and pain after PC were compared with those of patients who underwent PC for acute cholecystitis during the same period. Results Twenty patients underwent PC for biliary obstruction (cholangitis, 19; pancreatitis, 1). The technical and clinical success rates were 100%. The median serum total bilirubin level decreased considerably from 4.5 to 1.4 mg/dL after PC. An adverse event (catheter migration) occurred in 1 patient, and 17 patients developed pain after PC. During the same period, 104 patients underwent PC for cholecystitis. Adverse events occurred in 7 patients, and 62 developed pain. There was no significant difference in the adverse event rate between the cholangitis/pancreatitis and cholecystitis groups (5.0% vs. 6.7%, respectively), but pain occurred considerably more frequently in the cholangitis/pancreatitis group (94.4% vs. 63.9%, respectively). Conclusions PC is an effective and safe method for biliary decompression in selected patients. However, attention should be paid to postoperative pain.

Terahertz imaging of metastatic lymph nodes using spectroscopic integration technique.

Terahertz (THz) imaging was used to differentiate the metastatic states of frozen lymph nodes (LNs) by using spectroscopic integration technique (SIT). The metastatic states were classified into three groups: healthy LNs, completely metastatic LNs, and partially metastatic LNs, which were obtained from three mice without infection and six mice infected with murine melanoma cells for 30 days and 15 days, respectively. Under histological examination, the healthy LNs and completely metastatic LNs were found to have a homogeneous cellular structure but the partially metastatic LNs had interfaces of the melanoma and healthy tissue. THz signals between the experimental groups were not distinguished at room temperature due to high attenuation by water in the tissues. However, a signal gap between the healthy and completely metastatic LNs was detected at freezing temperature. The signal gap could be enhanced by using SIT that is a signal processing method dichotomizing the signal difference between the healthy cells and melanoma cells with their normalized spectral integration. This technique clearly imaged the interfaces in the partially metastatic LNs, which could not be achieved by existing methods using a peak point or spectral value. The image resolution was high enough to recognize a metastatic area of about 0.7 mm size in the partially metastatic LNs. Therefore, this pilot study demonstrated that THz imaging of the frozen specimen using SIT can be used to diagnose the metastatic state of LNs for clinical application.

Effect of Music on Reducing Anxiety for Patients Undergoing Transrectal Ultrasound-Guided Prostate Biopsies: Randomized Prospective Trial.

PURPOSE: The purpose of this study was to assess the impact of music on anxiety and perceived pain during transrectal ultrasound-guided prostate biopsy. MATERIALS AND METHODS: Forty consecutive men with an elevated serum prostate specific antigen (PSA) level and/ or an abnormal digital rectal examination referred for transrectal ultrasound-guided prostate biopsy were recruited and allocated to a music (n = 20) or a non-music (n = 20) group. Anxiety was assessed prior to and after biopsy and pain was assessed after biopsy in each patient using visual analog scales (VAS) in the same setting, and group anxiety scores were compared. RESULTS: Patients in the music group experienced less anxiety (P = .046) during the procedure, but group pain scores were not significantly different. CONCLUSION: Music was found to decrease anxiety effectively during transrectal ultrasound-guided prostate biopsy.

Neonatal head ultrasound: systematic approach to congenital Central Nervous System anomalies. A pictorial essay.

Brain ultrasound is widely used for the screening of prematurely born babies. Although the best imaging modality for the central nervous system anomaly is brain MRI, the first imaging study in the post-natal period is brain ultrasonography in most cases. Anomalies could be found incidentally on screening ultrasound, or in those cases already suspected on prenatal ultrasound. In order not to miss congenital structural abnormalities of the brain on screening ultrasound, systematic approaches would be very helpful. The ventricles and sylvian fissures are very important structures to suspect central nervous system anomalies: they are symmetric structures so we should look for any asymmetry or maldevelopment. And then, on sagittal images, the midline structures including the corpus callosum and cerebellar vermis should be observed carefully. Finally, we should look for any abnormality in gyration or cortical development. Skull defect with herniation of intracranial contents, a spectrum of encephalo-meningocele, could be also identified on ultrasound. Congenital infections such as cytomegalovirus infection may show ventriculomegaly and malformation of the cortical development on imaging studies.

Features of Pure Lobular Carcinoma In Situ on Magnetic Resonance Imaging Associated with Immediate Re-Excision after Lumpectomy.

PURPOSE: To evaluate imaging features of pure lobular carcinoma in situ (LCIS) on magnetic resonance imaging (MRI) in patients who underwent immediate re-excision after lumpectomy. METHODS: Twenty-six patients (46.1±6.7 years) with 28 pure LCIS lesions, who underwent preoperative MRI and received curative surgery at our institution between 2005 and 2013, were included in this study. Clinicopathologic features associated with immediate re-excision were reviewed and analyzed using Fisher exact test or the Wilcoxon signed rank test. RESULTS: Of the 28 lesions, 21.4% (6/28, six patients) were subjected to immediate re-excision due to resection margin involvement by LCIS. Nonmass lesions and moderate-to-marked background parenchymal enhancement on MRI were more frequently found in the re-excision group than in the single operation group (100% [6/6] vs. 40.9% [9/22], p=0.018; 83.3% [5/6] vs. 31.8% [7/22], p=0.057, respectively). The median lesion size discrepancy observed between magnetic resonance images and histopathology was greater in the re-excision group than in the single operation group (-0.82 vs. 0.13, p=0.018). There were no differences in the mammographic or histopathologic findings between the two groups. CONCLUSION: Nonmass LCIS lesions or moderate-to-marked background parenchymal enhancements on MRI can result in an underestimation of the extent of the lesions and are associated with subsequent re-excision due to resection margin involvement.

Computerized scheme for assessing ultrasonographic features of breast masses.

RATIONALE AND OBJECTIVE: To evaluate the ultrasonographic features of breast masses using a computerized scheme and to correlate the feature values with radiologists' grading. MATERIALS AND METHODS: One hundred and seventy-five breast ultrasound images (one to five images per subject) from 61 women (age 17-89 years, mean 43 years) were studied. Thirty-eight of the 157 images were from 11 women with malignant lesions, and the remaining 137 were from 50 patients with benign lesions. Two breast imaging radiologists participated in an observer performance study and were asked to grade, on a scale of 3, shape (1: regular, 3: very irregular), border (1: sharp, 3: ill-defined), internal texture (1: homogeneous, 3: very heterogeneous), width/depth ratio (1: flat, 3: tall), posterior enhancement (1: strong, 3: none), and lateral shadowing (1: strong, 3: none). The computerized scheme analyzed the breast region within a region of interest that was placed by a radiologist and quantified the following parameters: shape (jag count, disperse, convex hull depth, and lobulation count), border (acutance, average maximum ascending gradient, and sigmoid curve fitting), texture (edge density, co-occurrence matrix, and fractal dimension), width-depth ratio, posterior enhancement, and lateral shadowing. Correlations between the radiologists and the computerized scheme for assessing parameters in corresponding categories were computed. RESULTS: Good agreement was seen in posterior enhancement (P < .001, r = 0.45), lateral shadowing (P < .001, r = 0.38), width-depth ratio (P < .001, r = 0.33), and shape features (all P < .001): jag count (r = 0.38), disperseness (r = 0.55), and convex hull depth (r = 0.44). The remaining parameters demonstrated a poor or weak correlation (r < 0.30). CONCLUSION: The radiologists and the computerized scheme correlated best in analysis of shape features and posterior enhancement. We have yet to determine the significance of these features for the implementation of a computer-aided diagnosis program for characterizing breast ultrasound masses.

Chemoembolization for hepatocellular carcinoma supplied by a lumbar artery.

PURPOSE: To describe the radiologic findings and imaging response of hepatocellular carcinoma (HCC) supplied by the lumbar artery. METHODS: Between April 2004 and December 2012, we encountered HCC supplied by a lumbar artery in 21 patients. Two investigators retrospectively reviewed clinical and radiological findings of HCC supplied by the lumbar artery using computed tomography (CT) scans and digital subtraction angiograms. RESULTS: Patients had received 1-27 sessions of previous chemoembolization procedures (mean 7.7 sessions, median 4 sessions). Mean tumor size was 5.3 cm. The locations of HCC supplied by lumbar artery were the bare area (n = 14, 67 %) and segment VI (n = 7, 33 %). Tumor-feeding arteries arose from the main lumbar artery (n = 7), proximal anterior division (n = 4), and distal anterior division (n = 14). In 20 patients, selective chemoembolization through the tumor-feeding arteries of the lumbar artery was achieved. In 1 patient, nonselective embolization at the main lumbar artery was performed. There was no complication such as skin necrosis or paralysis. On the first follow-up enhanced CT scan, target tumors fed by the lumbar artery showed complete response (n = 6), partial response (n = 4), stable disease (n = 3), and progressive disease (n = 8), but overall tumor response was partial response (n = 1) and progressive disease (n = 20). CONCLUSION: When HCC is located in the inferior tip or bare area of the liver, a lumbar artery may supply the tumor. Although selective chemoembolization via the tumor-feeding vessel of the lumbar artery can be achieved in most cases, overall tumor response is commonly unfavorable.

In-vivo proton magnetic resonance spectroscopy in adnexal lesions.

OBJECTIVE: To explore the in-vivo 1H- MR spectral features of adnexal lesions and to characterize the spectral patterns of various pathologic entities. MATERIALS AND METHODS: Thirty-one patients with surgically and histopathologically confirmed adnexal lesions underwent short echo-time STEAM (stimulated echo acquisition method) 1H- MR spectroscopy, and the results obtained were analysed. RESULTS: The methylene present in fatty acid chains gave rise to a lipid peak of 1.3 ppm in the 1H- MR spectra of most malignant tumors and benign teratomas. This same peak was not observed, however, in the spectra of benign ovarian epithelial tumors: in a number of these, a peak of 5.2 ppm, due to the presence of the olefine group (-CH=CH-) was noted. The ratios of lipid peak at 1.3 ppm to water peak (lipid/water ratios) varied between disease groups, and in some benign teratomas was characteristically high. CONCLUSION: An intense lipid peak at 1.3 ppm is observed in malignant ovarian tumors but not in benign epithelial tumors. 1H- MRS may therefore be helpful in the differential diagnosis of adnexal lesions.

Pretreatment evaluation with contrast-enhanced ultrasonography for percutaneous radiofrequency ablation of hepatocellular carcinomas with poor conspicuity on conventional ultrasonography.

OBJECTIVE: To determine whether pretreatment evaluation with contrast-enhanced ultrasonography (CEUS) is effective for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) with poor conspicuity on conventional ultrasonography (US). MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and informed consent was waived. From June 2008 to July 2011, 82 patients having HCCs (1.2 ± 0.4 cm) with poor conspicuity on planning US for RFA were evaluated with CEUS prior to percutaneous RFA. We analyzed our database, radiologic reports, and US images in order to determine whether the location of HCC candidates on planning US coincide with that on CEUS. To avoid incomplete ablation, percutaneous RFA was performed only when HCC nodules were identified on CEUS. The rate of technical success was assessed. The cumulative rate of local tumor progression was estimated with the use of the Kaplan-Meier method (mean follow-up: 24.0 ± 13.0 months). RESULTS: Among 82 patients, 73 (89%) HCCs were identified on CEUS, whereas 9 (11%) were not. Of 73 identifiable HCCs on CEUS, the location of HCC on planning US corresponded with that on CEUS in 64 (87.7%), whereas the location did not correspond in 9 (12.3%) HCCs. Technical success was achieved for all 73 identifiable HCCs on CEUS in a single (n = 72) or two (n = 1) RFA sessions. Cumulative rates of local tumor progression were estimated as 1.9% and 15.4% at 1 and 3 years, respectively. CONCLUSION: Pretreatment evaluation with CEUS is effective for percutaneous RFA of HCCs with poor conspicuity on conventional US.