Focal Nodular Hyperplasia of the Liver: Contrast-Enhanced Ultrasonographic Features With Sonazoid.

OBJECTIVES: To investigate ultrasonographic features of focal nodular hyperplasia of the liver with contrast-enhanced ultrasonography (CEUS) using Sonazoid (perflubutane; GE Healthcare, Oslo, Norway). METHODS: Thirty-one patients with 31 focal nodular hyperplasia nodules who underwent CEUS using Sonazoid between July 2012 and February 2015 were included in this study. After the microbubble contrast agent was injected, intermittent CEUS images were obtained during the following 4 phases: arterial (10-40 seconds), portal venous (60-90 seconds), delayed (3 minutes), and Kupffer (>10 minutes). Three abdominal radiologists retrospectively reviewed the images and achieved consensus for vascular (central artery, stellate vascularity, and centrifugal enhancement) and dynamic enhancement patterns during the late arterial, portal venous, delayed, and Kupffer phases. RESULTS: The patients included 12 men and 19 women (age range, 21-82 years; mean, 47 years). The mean diameter of the lesions ± SD was 2.2 ± 0.9 cm (range, 1.0-4.0 cm). On CEUS, 24 of 31 lesions (77.4%) showed central artery and stellate vascularity in the early arterial phase, and 25 (80.6%) showed centrifugal enhancement. Twenty-six lesions (83.9%) were hyperechoic during the late arterial phase and showed hyperenhancement or isoenhancement during the serial dynamic phases. Kupffer-phase images indicated that only 2 lesions (6.5%) were hypoechoic compared with surrounding liver parenchyma, whereas 29 (93.5%) remained either hyperechoic (2 [6.5%]) or isoechoic (27 [87.1%]). CONCLUSIONS: Contrast-enhanced US using Sonazoid for focal nodular hyperplasia showed typical vascular patterns of central artery vascularity, stellate vascularity, and centrifugal enhancement. Most cases were either hyperenhanced or isoenhanced on serial dynamic- and Kupffer-phase imaging. Based on these results, CEUS can provide useful information for noninvasive focal nodular hyperplasia diagnoses.

Assessing patients with hepatocellular carcinoma meeting the Milan criteria: Is liver 3 tesla MR with gadoxetic acid necessary in addition to liver CT?

PURPOSE: To determine the added value of 3 Tesla liver MR in patients with hepatocellular carcinoma (HCC) within the liver computed tomography (CT) -based Milan criteria. MATERIALS AND METHODS: Liver CT and MR images of 130 patients with HCC within the Milan criteria based on liver CT were retrospectively reviewed. The number of MR-diagnosed HCCs and that of high risk hypervascular nodules (HRHNs), the effect of obtaining MR on patient management and CT appearances of MR-diagnosed HCCs and those of HRHNs were evaluated. Independent predictor for diagnosing additional HCCs on liver MR was analyzed. RESULTS: A total of 18.5% (24/130) of patients had additional 39 HCCs on MR, with a 5.4% (7/130) dropout rate from the Milan criteria. 28.5% (37/130) of patients had additional 78 HRHNs. Overall, 39.2% (51/130) of patients required changes in management. The common CT appearances of MR-diagnosed HCCs were arterial enhancing lesions ≥ 0.5cm (38.4%, 15/39), low density nodules < 1.5 cm (30.8%, 12/39) and invisibility (28.2%, 11/39). For MR-diagnosed HRHNs, 55.1% (43/78) were invisible on CT. The presence of inconclusive lesions on CT was an independent predictor for diagnosing additional HCCs on MR. CONCLUSION: For patients with HCCs within the Milan criteria on liver CT, liver MR may be necessary to detect additional HCCs and HRHNs.

Mistargeting after fusion imaging-guided percutaneous radiofrequency ablation of hepatocellular carcinomas.

PURPOSE: To evaluate the incidence and causes of mistargeting after fusion imaging-guided percutaneous radiofrequency (RF) ablation of hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Between 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. RESULTS: The 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). CONCLUSIONS: The 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.

Planning US for percutaneous radiofrequency ablation of small hepatocellular carcinomas (1-3 cm): value of fusion imaging with conventional US and CT/MR images.

PURPOSE: To assess whether fusion of conventional ultrasonography (US) with liver computed tomography/magnetic resonance images for planning US for percutaneous radiofrequency (RF) ablation can reduce false-positive detection and enhance lesion detectability of small hepatocellular carcinomas (HCCs) on conventional US. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board, and informed consent was waived. A total of 137 patients with single HCCs (mean ± standard deviation, 1.7 ± 0.6 cm; range, 1.1-3.0 cm) were included. Planning US was performed by two radiologists by using conventional US first and fusion imaging later in the same session. The false-positive detection rate of conventional US was assessed with the results of fusion imaging used as a reference standard. True-positive detection rates on conventional US and fusion imaging were compared by McNemar test. Initially undetectable HCCs on conventional US that became detectable after image fusion were also assessed. RESULTS: The false-positive detection rate of conventional US was 7.7% (nine of 117). Overall true-positive detection rates on conventional US and fusion imaging were 78.8% (108 of 137) and 90.5% (124 of 137), respectively (P = .0002); the rates were significantly different between conventional US and fusion imaging for HCCs smaller than 2.0 cm, but not for HCCs 2.0 cm or larger. Of 20 initially undetectable HCCs on conventional US, nine (45.0%) became detectable after image fusion. CONCLUSIONS: Fusion imaging for planning US for percutaneous RF ablation can reduce false-positive detection and enhance lesion detectability of small HCCs on conventional US.

Fusion imaging-guided radiofrequency ablation for hepatocellular carcinomas not visible on conventional ultrasound.

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.

Fusion imaging-guided percutaneous biopsy of focal hepatic lesions with poor conspicuity on conventional sonography.

OBJECTIVES: The purpose of this study was to evaluate the effectiveness of real-time fusion imaging (sonography combined with computed tomography or magnetic resonance imaging) for percutaneous sonographically guided biopsy of focal hepatic lesions with poor sonographic conspicuity. METHODS: This study was conducted as a retrospective analysis of a prospective database and was approved by the Institutional Review Board. Patients who had target lesions with poor conspicuity on B-mode sonography for percutaneous biopsy were enrolled in the study. Lesion conspicuity was assessed by conventional B-mode sonography first and then by fusion imaging later in the same session. We compared lesion conspicuity and detection rates between B-mode sonography and fusion imaging and evaluated how many cases of initially invisible lesions on B-mode sonography became visible on fusion imaging. The technical success rate was evaluated on the basis of the final diagnoses, which were established by pathologic examination of the biopsy specimens as well as follow-up clinical and radiologic examinations. RESULTS: A total of 22 patients were enrolled in the study. On fusion imaging, lesion conspicuity was increased in 63.6% of focal hepatic lesions (14 of 22). Moreover, 66.7% of lesions (6 of 9) that were invisible on B-mode sonography became visible on fusion imaging. The true-positive detection rate was significantly different between B-mode sonography and fusion imaging (9 of 22 versus 19 of 22; P = .0044). Percutaneous biopsy was performed for all lesions, including 3 target lesions that were invisible even on fusion imaging. The technical success rate was 95.5% (21 of 22). CONCLUSIONS: Fusion imaging is effective for percutaneous biopsy of focal hepatic lesions with poor sonographic conspicuity.

Size discrepancy between sonographic and computed tomographic/magnetic resonance imaging measurement of hepatocellular carcinoma: the necessity of tumor size measurement standardization.

OBJECTIVES: There is no standardized method for size measurement of hepatocellular carcinoma. The purpose of this study was to evaluate whether the size and stage of hepatocellular carcinoma differ according to the imaging modality. METHODS: This retrospective study was approved by our Institutional Review Board, and written informed consent was waived. Patients with hepatocellular carcinoma who underwent either computed tomography (CT) or magnetic resonance imaging (MRI) along with planning sonography for radiofrequency ablation on the same day were included. A total of 113 patients with 127 hepatocellular carcinomas were included. The sizes of the tumors were measured and the tumor stages were assessed on CT/MRI and sonography. The results were compared by a t test, Bland-Altman limits of agreement, and a McNemar test. RESULTS: There was a significant difference in the hepatocellular carcinoma size between CT/MRI and sonographic measurements (mean difference, 0.26 cm; P < .0001). The sizes of 102 tumors (80.3%) were larger on sonography than on CT/MRI. Twelve tumors (9.5%) were the same size and 13 (10.2%) were smaller on sonography than on CT/MRI. There was also difference in the tumor stage (very early or not) between CT/MRI and sonography (P= .006, McNemar test). The stage was discordant in 16 of 127 tumors (12.6%). Among 69 tumors at the very early stage on CT/MRI, 14 (20.3%) were beyond the very early stage on sonography. CONCLUSIONS: The size of hepatocellular carcinoma measured on sonography tends to be larger than on CT/MRI; therefore, the tumor stage can differ between sonography and CT/MRI.

MR thermometry analysis of sonication accuracy and safety margin of volumetric MR imaging-guided high-intensity focused ultrasound ablation of symptomatic uterine fibroids.

PURPOSE: To evaluate the accuracy of the size and location of the ablation zone produced by volumetric magnetic resonance (MR) imaging-guided high-intensity focused ultrasound ablation of uterine fibroids on the basis of MR thermometric analysis and to assess the effects of a feedback control technique. MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and written informed consent was obtained. Thirty-three women with 38 uterine fibroids were treated with an MR imaging-guided high-intensity focused ultrasound system capable of volumetric feedback ablation. Size (diameter times length) and location (three-dimensional displacements) of each ablation zone induced by 527 sonications (with [n=471] and without [n=56] feedback) were analyzed according to the thermal dose obtained with MR thermometry. Prospectively defined acceptance ranges of targeting accuracy were ±5 mm in left-right (LR) and craniocaudal (CC) directions and ±12 mm in anteroposterior (AP) direction. Effects of feedback control in 8- and 12-mm treatment cells were evaluated by using a mixed model with repeated observations within patients. RESULTS: Overall mean sizes of ablation zones produced by 4-, 8-, 12-, and 16-mm treatment cells (with and without feedback) were 4.6 mm±1.4 (standard deviation)×4.4 mm±4.8 (n=13), 8.9 mm±1.9×20.2 mm±6.5 (n=248), 13.0 mm±1.2×29.1 mm±5.6 (n=234), and 18.1 mm±1.4×38.2 mm±7.6 (n=32), respectively. Targeting accuracy values (displacements in absolute values) were 0.9 mm±0.7, 1.2 mm±0.9, and 2.8 mm±2.2 in LR, CC, and AP directions, respectively. Of 527 sonications, 99.8% (526 of 527) were within acceptance ranges. Feedback control had no statistically significant effect on targeting accuracy or ablation zone size. However, variations in ablation zone size were smaller in the feedback control group. CONCLUSION: Sonication accuracy of volumetric MR imaging-guided high-intensity focused ultrasound ablation of uterine fibroids appears clinically acceptable and may be further improved by feedback control to produce more consistent ablation zones.

Planning ultrasound for percutaneous radiofrequency ablation to treat small (≤ 3 cm) hepatocellular carcinomas detected on computed tomography or magnetic resonance imaging: a multicenter prospective study to assess factors affecting ultrasound visibility.

PURPOSE: To assess factors affecting tumor visibility on planning ultrasound (US) for percutaneous radiofrequency (RF) ablation to treat small hepatocellular carcinomas (HCCs) primarily detected on computed tomography (CT) or magnetic resonance (MR) imaging. MATERIALS AND METHODS: Patients referred for planning US for percutaneous RF ablation between September 2008 and June 2009 were prospectively enrolled from nine institutions in Korea. The first small (≤ 3 cm) single HCC or new single HCC after treatment was included. The study enrolled 898 patients (684 men and 214 women, age range 32-86 years). HCCs that were invisible on planning US were compared with visible HCCs with respect to tumor size, distance between the tumor and the diaphragm, subcapsular location, etiology of liver disease, liver cirrhosis, macronodular cirrhosis on US, ascites, Child-Pugh class, serum alpha fetoprotein (AFP) level, body mass index (BMI), previous treatments for HCC, previous chemoembolization treatments for HCC, institutions, and experience of radiologists. RESULTS: Among 898 HCCs, 671 (74.7%) were visible on the planning US. In multivariate analysis, tumor size, distance between the tumor and the diaphragm, liver cirrhosis, and macronodular cirrhosis were statistically significant factors affecting US detection (each P < .05). CONCLUSIONS: Smaller tumors, subphrenic location of the tumor, liver cirrhosis, and macronodular cirrhosis were independent predictors of invisible tumors on planning US.

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.

Comparison between transauricular and transfemoral arterial access for hepatic artery angiography in a rabbit model.

PURPOSE: To evaluate the feasibility of transauricular arterial access and compare the procedure time needed for hepatic artery angiography via transfemoral versus transauricular arterial access in a rabbit model. MATERIALS AND METHODS: This study was approved by the research animal care and use committee. Twenty rabbits were divided into transfemoral (n = 10) and transauricular access groups (n = 10). The procedure consisted of shaving the hair, obtaining intraarterial access, performing hepatic artery angiography, and repairing the access site. A Mann-Whitney U test was used to compare the two groups in terms of the total procedure time and the time needed for each step. RESULTS: Hepatic artery angiography was technically feasible in all animals in both groups. The time required for shaving was 55 seconds ± 9.9 in the transfemoral access group; shaving was unnecessary in the transauricular access group. The times needed to obtain intraarterial access, perform hepatic artery angiography, repair the access site, and perform the entire procedure in the transfemoral and transauricular access groups were as follows: 503.3 s ± 211.8 and 97 s ± 83.3 (P < .001), 229.6 s ± 90 and 310.7 s ± 211 (P = .705), 305.5 s ± 80.6 and 90 s ± 0 (P < .001), and 1,038 s ± 265.9 and 497.7 s ± 256.9 (P = 0.001), respectively. CONCLUSIONS: Hepatic artery angiography is technically feasible via transauricular arterial access. The major advantages of transauricular arterial access versus transfemoral arterial access include a procedure time reduced by the omission of shaving and surgical cutdown.

Venous thrombosis after radiofrequency ablation for hepatocellular carcinoma.

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.

Radiofrequency ablation for hepatocellular carcinoma abutting the diaphragm: comparison of effects of thermal protection and therapeutic efficacy.

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.

Recurrent hepatocellular carcinoma after transcatheter arterial chemoembolization: planning sonography for radio frequency ablation.

OBJECTIVES: The purposes of this study were to evaluate the sonographic findings of recurrent hepatocellular carcinoma after transcatheter arterial chemoembolization and to determine how often the lesion conspicuity of the recurrent hepatocellular carcinoma makes it suitable for percutaneous sonographically guided radio frequency ablation. METHODS: A radiologist prospectively classified the echogenicity of recurrent hepatocellular carcinomas compared to that of the surrounding liver. In addition, the margin of the tumor was classified as follows: grade 1, absolutely indistinguishable; grade 2, less than 50%; grade 3, greater than 50%; and grade 4, clearly demarcated. The lesion conspicuity was also classified as follows: grade 1, absolutely invisible, thus ineligible for percutaneous sonographically guided radio frequency ablation; grade 2, poorly visible, thus unsuitable for ablation; and grade 3, visible and conspicuous, thus suitable for ablation. RESULTS: A total of 37 consecutive patients (31 men and 6 women; mean age, 59.4 years) with 38 hepatocellular carcinomas were enrolled. The echogenicity of the recurrent hepatocellular carcinomas varied, with the most common finding being a heterogeneous hypoechoic lesion (31.6%), followed by an isoechoic lesion (23.7%), a heterogeneous hyperechoic lesion (18.4%), a homogeneous hypoechoic lesion (13.2%), a lesion with a hypoechoic halo (10.5%), and a homogeneous hyperechoic lesion (2.7%). The margin of the recurrent hepatocellular carcinomas was clearly demarcated in only 28.9% of tumors, whereas 23.7% of the tumors were absolutely indistinguishable from the surrounding liver. The lesion conspicuity was classified as grade 3 in only 60.5% of the recurrent hepatocellular carcinomas. CONCLUSIONS: The echogenicity and margins of recurrent hepatocellular carcinomas after transcatheter arterial chemoembolization varied. The lesion conspicuity was suitable for sonographically guided radio frequency ablation in only 60.5% of cases.

Percutaneous sonographically guided radio frequency ablation of hepatocellular carcinoma: causes of mistargeting and factors affecting the feasibility of a second ablation session.

OBJECTIVES: The purposes of this study were to evaluate the causes of mistargeting during percutaneous sonographically guided radio frequency ablation in patients with hepatocellular carcinoma and to determine factors affecting the feasibility of a second ablation session. METHODS: This study received Institutional Review Board approval, and informed consent was waived. Among 2213 percutaneous sonographically guided radio frequency ablations performed in our hospital, we searched for mistargeting cases and analyzed the causes of mistargeting. To determine which factors affected the feasibility of a second ablation session, univariate and multivariate analyses were performed. RESULTS: Forty-one cases of mistargeting occurred during the first ablation session, and 4 cases occurred during the second session. Of the 41 patients with mistargeted hepatocellular carcinomas during the first session, 39 who underwent replanning sonography were able to be analyzed for causes of mistargeting. The most common cause of mistargeting was confusion with cirrhotic nodules (87.2% [34 of 39]), followed by poor conspicuity of the hepatocellular carcinoma (69.2% [27 of 39]), a poor sonic window (28.2% [11 of 39]), a poor electrode path (7.7% [3 of 39]), and inaccurate electrode placement (2.6% [1 of 39]). Artificial ascites (P = .035) and the presence of more than 3 mistargeting causes (P = .017) were independent factors affecting feasibility. CONCLUSIONS: The most common cause of mistargeting was confusion with cirrhotic nodules, followed by poor conspicuity of the hepatocellular carcinoma, a poor sonic window, a poor electrode path, and inaccurate electrode placement. The use of artificial ascites and the presence of more than 3 mistargeting causes were factors affecting the feasibility of a second radio frequency ablation session.

Gadoxetic acid-enhanced MRI versus multiphase multidetector row computed tomography for evaluating the viable tumor of hepatocellular carcinomas treated with image-guided tumor therapy.

PURPOSE: To compare the diagnostic performance of gadoxetic acid-enhanced MRI with that of multi-phase 40- or 64-multidetector row computed tomography (MDCT) to evaluate viable tumors of hepatocellular carcinomas (HCCs) treated with image-guided tumor therapy. MATERIALS AND METHODS: A total of 108 patients with 162 HCCs (56 lesions with viable tumor and 106 without viable tumor) treated by means of transcatheter arterial chemoembolization or radiofrequency ablation were retrospectively included in this study. All patients underwent multi-phase CT at 40- or 64-MDCT and gadoxetic acid-enhanced MRI using 3.0 Tesla (T). Two observers independently and randomly reviewed the CT and MR images of the treated lesions. The diagnostic performance of two techniques for the evaluation of the viable tumors in the treated lesions was assessed with a receiver operating characteristic (ROC) analysis. RESULTS: For each observer, the areas under the ROC curve were 0.953 and 0.969 for MRI, and 0.870 and 0.888 for MDCT (P < 0.05). The diagnostic accuracies (96.3% for each observer) and sensitivities (92.9% and 96.4%) of MRI in two observers were significantly higher than those (82.7% and 80.9%, 53.6% for each observer, respectively) of MDCT (P < 0.001). The negative predictive values (96.3% and 98.1%) of MRI in two observers were significantly higher than those (80.0% and 79.5%) of MDCT (P < 0.001). For each observer, specificities and positive predictive values did not differ significantly between the two techniques (P > 0.05). CONCLUSION: Gadoxetic acid-enhanced MRI shows better diagnostic performance than that of MDCT for evaluating the viable tumors of HCCs treated with image-guided tumor therapy.

Comparison between areas with Gd-EOB-DTPA uptake and without in hepatocellular carcinomas on Gd-EOB-DTPA-enhanced hepatobiliary-phase MR imaging: pathological correlation.

PURPOSE: To determine histological and MR imaging differences between areas with Gd-EOB-DTPA (gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid) uptake and without in hepatocellular carcinomas (HCCs) as seen on Gd-EOB-DTPA-enhanced hepatobiliary-phase MR images. MATERIALS AND METHODS: This study included nine patients with nine histopathologically proven HCCs (mean size, 1.9 cm) that consisted of two portions of a non-hypointense (Gd-EOB-DTPA uptake) and hypointense area (no Gd-EOB-DTPA uptake) in one tumor as depicted on hepatobiliary-phase MR images. Two radiologists and one pathologist compared the histological and MR finding differences between the two portions in consensus. RESULTS: In eight specimens, non-hypointense areas of six specimens showed a green color and two specimens did not show a green color. Microscopically, two of nine showed a higher percentage of bile pigments in the non-hypointense area as compared to the hypointense area and the remaining seven showed no difference. Six were homogeneous Edmondson-Steiner grade II, and one was grade I. In two, non-hypointense areas were grade II and hypointense areas were grade I. No difference between the two portions was found for necrosis, hemorrhage, fibrosis, and a fibrous capsule. Seven on T1/T2-weighted images and eight on arterial and portal phase images showed no different signal intensity between the two portions. CONCLUSION: Although macroscopically, a non-hypointense area of an HCC seen on GD-EOB-DTPA-enhanced hepatobiliary-phase images may be associated with the area with a green color, no definite microscopic and MR imaging findings that could discriminate a non-hypointense from a hypointense area of an HCC was found.

Outcomes of follow-up CT for small (5-10-mm) arterially enhancing nodules in the liver and risk factors for developing hepatocellular carcinoma in a surveillance population.

OBJECTIVE: To evaluate the outcomes of small (5-10 mm), arterially enhancing nodules (SAENs) shown exclusively at the hepatic arterial phase of CT in a hepatocellular carcinoma (HCC) surveillance population and to determine risk factors for developing HCC. METHODS: The study population included 112 patients (male:female = 100:12; aged 36-92 years) with 175 SAENs who were at risk of HCC. We evaluated serial changes during follow-up (1.4-41.8 months, mean 35.7 months) and analysed the initial CT findings of SAENs and the accompanying lesions to elucidate the risk factors for HCC development. RESULTS: Of 175 SAENs, 101(57.7%) disappeared and 34(19.4%) persisted. Forty SAENs (22.9%) became HCC in 33 patients (29.5%). Presence of HCC treatment history (p = 0.005, risk ratio = 7.429), a larger size of SAEN (p = 0.003, risk ratio = 1.630), presence of coexistent HCC (p = 0.021, risk ratio = 3.777) and absence of coexistent typical arterioportal shunts (p = 0.003, risk ratio = 4.459) turned out to be independently significant risk factors for future development of HCC. CONCLUSION: SAENs were frequently seen in an HCC surveillance population and have a 22.9% probability of becoming HCC on a per-lesion basis. Risk increased particularly when the lesion was associated with a previous or concurrent HCC, a large size or found without a coexistent typical arterioportal shunt.

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 for hepatic tumors abutting the diaphragm: clinical assessment of the heat-sink effect of artificial ascites.

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.