Virtual Sonographic Radiofrequency Ablation of Hepatocellular Carcinoma Visualized on CT but Not on Conventional Sonography

Efficacy and safety of no-touch radiofrequency ablation for small hepatocellular carcinoma-a systematic review and single-arm meta-analysis

OBJECTIVE

The purpose of this study was to report the efficacy and safety of no-touch radiofrequency ablation (NT-RFA) in the treatment of small hepatocellular carcinoma (HCC).

METHODS

We systematically searched for eligible studies in PubMed, Embase and Cochrane library until June 1, 2022. Random effect model was applied to synthesize the pooled proportions of local tumor progression-free survival (LTP), recurrence-free survival (RFS) and overall survival (OS) respectively, as well as adverse events, for small HCC treated by NT-RFA.

RESULTS

Of the 10 included studies, 3 of them reported local tumor recurrence. One reported local tumor recurrence at 19 months (range, 12-24), and 2 studies had no tumor recurrence with 24-months of follow-up. The 1- and 2-year LTP pooled proportions were 99.3% (95%CI, 97.5-100) and 97.8% (95%CI, 94.6-99.6) respectively, and two studies reported a 3-year LTP rate of 96.4% (204/212, 36/37). The 1-yearRFS rates was 91.3% (95%CI, 84.1-98.4), 2-year was 86.4% (95%CI, 75.3-97.5). The 1-, 2- and 3- year OS rates were 92.4% (95%CI, 82.8-92.7), 84.1% (95%CI, 74.7-93.6) and 81.8% (116/181, 33/36) respectively, and only one study reported a 5-year OS rate of 47.0% (85/181). The ablative success rate of the HCC nodules was 96.6% (95%CI, 91.3-99.5) and the proportions of mild and severe adverse events following ablation were 18.3% (95%CI, 8.1-41.6) and 5.0%, respectively.

CONCLUSION

NT-RFA provides safely very high rate of sustained local control for the treatment of HCC up to 5 cm.

Comparison of Surgical Resection and Percutaneous Ultrasonographic Guided Radiofrequency Ablation for Initial Recurrence of Hepatocellular Carcinoma in Early Stage following Curative Treatment

Background/Aim: The SURF trial showed that surgical resection (SR) and percutaneous ultrasonographic guided radiofrequency ablation (RFA) had equal therapeutic effects for small hepatocellular carcinoma (HCC). However, consensus regarding which treatment is appropriate for initial recurrent early-stage HCC remains lacking. This study aimed to elucidate therapeutic efficacy differences between SR and RFA for initial recurrent early-stage HCC. Materials/Methods: From 2000 to 2021, 371 patients with recurrent early-stage HCC (≤3 cm, ≤3 nodules) after undergoing initial curative treatment with SR or RFA were enrolled (median age 72 years; males 269; Child−Pugh A:B, n = 328:43; SR:RFA, n = 36:335). Recurrence-free survival (RFS) and overall survival (OS) were retrospectively evaluated. Results: Although the median albumin−bilirubin (ALBI) score was better in the SR than the RFA group (−2.90 vs. −2.50, p < 0.01), there were no significant differences between them in regard to RFS (median 28.1 months, 95% CI 23.4−50.0 vs. 22.1 months, 95% CI 19.3−26.2; p = 0.34), OS (78.9 months, 95% CI 49.3—not applicable vs. 71.2 months 95% CI, 61.8−84.7; p = 0.337), or complications (8.3% vs. 9.3%; p = 1.0). In sub-analysis for RFS and OS according to ALBI grade revealed no significant differences between the SR and RFA groups (ALBI 1/2 = 28.2/17.5 vs. 24.0/23.4 months; p = 0.881/0684 and ALBI 1/2 = 78.9/58.9 vs. 115.3/52.6 months, p = 0.651/0.578, respectively). Conclusion: This retrospective study found no significant differences in regard to RFS or OS between patients in the SR and the RFA groups for initial recurrence of early-stage HCC after undergoing curative treatment. These results showing equal therapeutic efficacy of SR and RFA confirm the findings of the SURF trial.

Real-time virtual sonography-assisted radiofrequency ablation in liver tumors with conspicuous or inconspicuous images or peritumoral landmarks under ultrasonography

Objectives

The objectives of this study were to determine the primary technique effectiveness (PTE), to compare the complete response and local recurrence rates between conspicuous and inconspicuous tumors using single and switching electrodes of real-time virtual sonography (RVS)-assisted radiofrequency ablation (RFA) in conspicuous and inconspicuous hepatic tumors under conventional ultrasonography (US).

Subjects and method

We compared the complete ablation of inconspicuous tumors with and without anatomical landmark (N = 54) with conspicuous liver tumors (N = 272). Conventional US imaging was done initially, and then these images were fused with CT or MRI arterial-venous-wash-out cross-sectional studies and synchronized with real-time US images.

Results

RVS-assisted RFA was technically feasible in all patients. The PTE rate after the first ablation was 94% (245/261) for conspicuous tumors, 88% (7/8) in inconspicuous tumors with landmark, and 78% (36/46) in inconspicuous tumors without landmark. The complete response (p = 0.1912 vs. p = 0.4776) and local recurrence rate (p = 0.1557 vs. p = 0.7982) were comparable in conspicuous tumors of both HCC and liver metastasis group when single or multiple switching was used. The cumulative local recurrence in the conspicuous and inconspicuous tumors of the HCC group (p = 0.9999) was almost parallel after 12 (10% vs. 4%) and 24 (13% vs. 4%) months of follow-up. In the liver metastasis group, the cumulative local recurrence for conspicuous tumors (p = 0.9564) was nearly equal after 12 and 24 months of monitoring (24% vs. 27%) while no recurrence was incurred for the inconspicuous tumors.

Conclusion

RVS-assisted RFA is an effective tool for the treatment of conspicuous and inconspicuous HCC and hepatic metastasis.

Image Guidance in Ablation for Hepatocellular Carcinoma: Contrast-Enhanced Ultrasound and Fusion Imaging

The ultrasound (US) imaging technology, including contrast-enhanced US (CEUS) and fusion imaging, has experienced radical improvement, and advancement in technology thus overcoming the problem of poor conspicuous hepatocellular carcinoma (HCC). On CEUS, the presence or absence of enhancement distinguishes the viable portion from the ablative necrotic portion. Using volume data of computed tomography (CT) or magnetic resonance imaging (MRI), fusion imaging enhances the three-dimensional relationship between the liver vasculature and HCC. Therefore, CT/MR-US fusion imaging provides synchronous images of CT/MRI with real-time US, and US-US fusion imaging provides synchronous US images before and after ablation. Moreover, US-US overlay fusion can visualize the ablative margin because it focuses the tumor image onto the ablation zone. Consequently, CEUS and fusion imaging are helpful to identify HCC with little conspicuity, and with more confidence, we can perform ablation therapy. CEUS/fusion imaging guidance has improved the clinical effectiveness of ablation therapy in patients with poor conspicuous HCCs. Therefore; this manuscript reviews the status of CEUS/fusion imaging guidance in ablation therapy of poor conspicuous HCC.

Ultrasound fusion imaging technologies for guidance in ablation therapy for liver cancer

With advances in imaging technology, images from ultrasound (US) and computed tomography (CT) or magnetic resonance imaging (MRI) can be displayed simultaneously and in real time, according to the angle of the transducer. CT/MR-US fusion imaging improves the visualization of inconspicuous hepatocellular carcinoma (HCC) and helps us to understand the three-dimensional relationship between the liver vasculature and HCC. US fusion imaging guidance facilitates improvement in the treatment response for HCC with poor conspicuity, and the rates of technical success of ablation and local tumor progression for inconspicuous HCC range from 94.4 to 100% and 0 to 8.3%, respectively. Moreover, the development of image fusion has made it possible to compare and overlay pre- and post-ablation US images. This US-US fusion imaging allows side-by-side comparison of the ablative margin, while US-US overlay fusion can visualize the ablative margin because the tumor image is projected onto the ablative hyperechoic zone. Thus, US-US overlay fusion guidance is highly effective for safety margin achievement in local ablation therapy for HCC, providing a lower risk of local tumor progression. This manuscript reviews the current status of ultrasound fusion imaging for percutaneous ablation therapy of HCC.

Intraprocedural contrast-enhanced ultrasound-CT/MR fusion imaging assessment in HCC thermal ablation to reduce local tumor progression: compared with routine contrast-enhanced ultrasound

Purpose: To evaluate whether local tumor progression (LTP) would be further reduced when contrast-enhanced ultrasound (CEUS)-CT/MR fusion imaging was used as intraprocedural assessment method in hepatocellular carcinoma (HCC) thermal ablation compared with routine CEUS. Materials and methods: This prospective non-randomized study was conducted from December 2010 to July 2012. CEUS-CT/MR fusion imaging and routine CEUS were used for treatment response assessment in the ablation procedure of 146 HCCs and 122 HCCs, respectively. Supplementary ablations were performed immediately if necessary. The primary technique efficacy rate, LTP rate and overall survival (OS) rate were calculated. Results: For CEUS-CT/MR fusion imaging and routine CEUS, the technical success rate, technique efficacy rate and supplementary ablation rate were 86.3% (126/146) and 98.4% (120/122) (p = .000), 99.2% (125/126) and 94.2% (113/120) (p = .032), and 14.3% (18/126) and 4.2% (5/120) (p = .006), respectively. The cumulative LTP rate and OS rate were not significantly different between fusion imaging group and routine CEUS group. However, for lesions that were larger than 3 cm or close to major vessels (41 lesions in fusion imaging group and 44 lesions in routine CEUS group, who received transcatheter arterial chemoembolization before ablation), the cumulative LTP rate was significantly lower in fusion imaging group than in routine CEUS group (p = .032). Conclusion: Although intraprocedural CEUS-CT/MR fusion imaging has certain limitations in application, it might provide a potential more efficient method compared with routine CEUS in reducing LTP in HCC thermal ablation, especially for difficult ablation lesions.

Ultrasonography surveillance improves prognosis of patients with hepatocellular carcinoma

To examine the effectiveness of ultrasonography (US) for hepatocellular carcinoma (HCC) surveillance, the prognosis of HCC patients who underwent such screening at an expert medical institution or at general clinics were analyzed, as well as those without US surveillance. From October 2006 to December 2014, 872 patients with naïve HCC were enrolled and divided into the surveillance (S)-group (n=398), who underwent follow-up examinations with US, and the non-S group (n=474). The S-group was further subdivided into patients who underwent follow-up surveillance at Ehime Prefectural Central Hospital, an expert medical institution (SE-group, n=189), and those who received surveillance at general clinics (SG-group, n=209). Prognosis and clinical characteristics were analyzed. In the non-S group, the frequency of patients without viral hepatitis (NBNC-HCC) and Tumor, Node, Metastasis stage was greater. As a result, the median survival time (MST) of the non-S group was reduced, compared with the S group (non-S group, 34.1 vs. S group, 68.2 months; P<0.001). Tumor size was significantly different between the SE- and SG-groups (SE-group, 2.0±1.0 vs. SG-group, 2.5±1.3 cm; P<0.001), whereas tumor number (SE-group: 1.5±1.1 vs. SG-group, 1.7±1.2; P=0.164) and MST (SE-group, 72.1 vs. SG-group, 67.1 months; P=0.931) were not significantly different. Surveillance performed at either an expert medical institution or general clinic improved the prognosis of HCC patients. Dissemination of findings demonstrating the importance of surveillance for HCC to all clinicians as well as patients with chronic liver disease is important, and establishment of an effective surveillance strategy for NBNC-HCC is required.

Fusion Image-Guided and Ultrasound-Guided Fine Needle Aspiration in Patients With Suspected Hepatic Metastases

AIM

The aim of this study was to compare the diagnostic adequacy of computed tomography (CT)-ultrasound (US) fusion image-guided fine needle aspiration (FNA) and US-guided FNA in patients with suspected hepatic metastases.

METHODS

Thirty consecutive patients of either sex with known or unknown primary malignancy suspected of having liver metastases on both US and CT, whose multiphasic contrast-enhanced computed tomography was performed using a 64-slice or a higher slice CT scanner, and who were referred for percutaneous FNA were included in this prospective study approved by the institutional review board of the study institute. CT-ultrasound fusion image-guided FNA of the largest lesion using electromagnetic tracking and with freehand ultrasound-guided FNA were performed in the same sitting. Value of fitness, which is a rough estimate of how well the fusion has been achieved, was recorded. Diagnostic adequacy of smears was assessed by a scoring system based on cellular material, background blood/clot, degree of cellular degeneration or trauma, and retention of architecture.

RESULTS

The size of the lesions ranged from 1 to 10 cm, and the depth of location of the lesions ranged from 1.4 to 9.3 cm. The fusion fitness values ranged from 1.2 to 10 mm. The scores of the smears did not correlate with lesion size, depth of location, and fusion fitness value. Diagnostic adequacy was seen in 90% and 93.3% of lesions sampled by fusion image guidance and ultrasound guidance, respectively (p = 0.655). All the lesions that yielded inadequate smears by fusion guidance were deep-seated lesions (>5 cm). All the lesions that yielded inadequate smears by ultrasound guidance were small lesions (<3 cm). No complications were encountered in any of the patients.

CONCLUSION

Fusion image-guided FNA is a safe procedure with a high diagnostic adequacy rate. Fusion image-guided FNA is not better than US-guided FNA for conspicuous hepatic lesions; however, it may be useful in inconspicuous lesions.

Accuracy of a CT-Ultrasound Fusion Imaging Guidance System Used for Hepatic Percutaneous Procedures

PURPOSE

To evaluate the accuracy of a fusion imaging guidance system using ultrasound (US) and computerized tomography (CT) as a real-time imaging modality for the positioning of a 22-gauge needle in the liver.

MATERIALS AND METHODS

The spatial coordinates of 23 spinal needles placed at the border of hepatic tumors before radiofrequency thermal ablation were determined in 23 patients. Needles were inserted up to the border of the tumor with the use of CT-US fusion imaging. A control CT scan was carried out to compare real (x, y, z) and virtual (x', y', z') coordinates of the tip of the needle (D for distal) and of a point on the needle located 3 cm proximally to the tip (P for proximal).

RESULTS

The mean Euclidian distances were 8.5 ± 4.7 mm and 10.5 ± 5.3 mm for D and P, respectively. The absolute value of mean differences of the 3 coordinates (|x' - x|, |y' - y|, and |z' - z|) were 4.06 ± 0.9, 4.21 ± 0.84, and 4.89 ± 0.89 mm for D and 3.96 ± 0.60, 4.41 ± 0.86, and 7.66 ± 1.27 mm for P. X = |x' - x| and Y = |y' - y| coordinates were <7 mm with a probability close to 1. Z = |z' - z| coordinate was not considered to be larger nor smaller than 7 mm (probability >7 mm close to 50%).

CONCLUSIONS

Positioning errors with the use of US-CT fusion imaging used in this study are not negligible for the insertion of a 22-gauge needle in the liver. Physicians must be aware of such possible errors to adapt the treatment when used for thermal ablation.

Combination of Resection and Ablative Treatment for Hepatocellular Carcinoma: Usefulness of Complementary Radiofrequency Ablation

AIM/BACKGROUND

In HCC patients with multiple tumors in separate segments, monotherapy with surgical resection is often difficult when the estimated residual liver volume after surgery is thought to be inadequate. We evaluated the usefulness of resection combined with low invasive radiofrequency ablation (RFA) for treatment of such cases.

MATERIALS/METHODS

We analyzed 115 HCC patients with countable multiple tumors (≤5) without vascular invasion and/or extrahepatic metastasis, and treated solely with resection (SR group: n = 82), or with both resection and RFA (Comb group: n = 33) from January 2000 to December 2017. Clinical characteristics, overall survival rate (OSR), and disease-free survival rate (DFSR) were analyzed in a retrospective manner.

RESULTS

There were 88 males (76.5%) and the average age of all patients was 67.8 ± 8.9 years. The average number of tumors and average maximum tumor size were 2.4 ± 0.7 and 4.1 ± 2.1 cm, respectively. Forty-two (36.5%) patients were classified as beyond up-to-7 criteria. The 3- and 5-year OSRs in the SR group were 82.0 and 67.0%, respectively, and in the Comb group were 75.2 and 65.6%, respectively (p = 0.244), while the 3- and 5-year DFSRs in the SR group were 45.2 and 28.0%, respectively, and those in the Comb group were 37.3 and 23.3%, respectively (p = 0.257).

CONCLUSION

The combination of surgical resection and complementary RFA may be an effective strategy for treating HCC patients with countable multiple tumors, who are otherwise difficult to treat with surgical resection or RFA alone.

Prospective cohort trial to confirm the efficacy of no-touch radio frequency ablation

BACKGROUND AND AIM

The aim of the present prospective study was to evaluate tumor recurrence (intrasubsegmental recurrence-free survival and local tumor recurrence-free survival) and hepatic functional reserve following no-touch ablation.

METHODS

The prospective cohort study protocols were approved by the institutional ethics committee. All patients provided written, informed consent. Between January 2014 and September 2016, 231 patients with 277 hepatocellular carcinoma nodules were prospectively enrolled. An internally cooled bipolar electrode was used for no-touch ablation, while a monopolar electrode was used for direct puncture ablation. The intrasubsegmental recurrence-free survival rate was the primary end-point. The secondary outcomes were the local recurrence-free survival rate, the disease-free survival rate, and the changes in the Child-Pugh score.

RESULTS

No-touch ablation resulted in significantly higher cumulative intrasubsegmental tumor recurrence-free survival rates than direct puncture ablation (98.0% vs 87.1% at 1 year, 96.9% vs 76.8% at 2 years, and 91.0% vs 68.3% at 3 years, P < 0.001). The no-touch group also showed significantly better local recurrence-free survival and disease-free survival. Even when only primary cases were analyzed, the same results were obtained. To adjust for differences in the background characteristics, inverse probability of treatment weighting adjustment was performed. Only intrasubsegmental tumor recurrence-free survival was significantly better in the no-touch group (hazard ratio [HR], 0.08; 95% confidence interval [CI], 0.02-0.20, P < 0.001); there was no difference in local tumor recurrence-free survival (HR, 0.36; 95% CI, 0.10-1.02, P = 0.071).

CONCLUSIONS

No-touch ablation appears to be an ideal method for the prevention of intrahepatic dissemination.

Precise Navigation of the Surgical Plane with Intraoperative Real-time Virtual Sonography and 3D Simulation in Liver Resection

The precise intraoperative navigation of the surgical plane remains challenging in liver surgery; however, an innovative imaging technique-real-time virtual sonography (RVS)-may provide a solution. In this modality, preoperative three-dimensional (3D) resection simulation data are transmitted to an RVS workstation and can be used in combination with intraoperative ultrasound to navigate the surgical plane in real time. This paper describes this technique and our experiences in detail. From November 2015 to March 2017, 26 patients with primary liver cancer underwent liver resection under RVS navigation. The operative procedures employed included hemihepatectomy, bisegmentectomy, segmentectomy, and limited resection. RVS was utilized uneventfully and successfully in each operation. The median time required for spatial position registration was 3 (1-12) min, and as the case volume increased, the time required for registration markedly decreased. The surgical plane under RVS navigation was consistent with that of the preoperative plan, and the resection margin was confirmed negative in each case. In conclusion, RVS in combination with 3D simulation is a feasible, safe, and promising technique for the precise intraoperative navigation of liver resection for primary liver cancer. It could be applied to other resectable liver diseases and may be utilized in other centers.

Validation trial for efficacy of ultrasonographic measurement method to predict ascitic volume using virtual ultrasonography

PURPOSE

The aim of this study was to clarify whether ultrasound quantitative methods were positively correlated with volume of ascites evaluated by whole abdominopelvic CT.

METHODS

Sixty-eight patients with cirrhotic ascites were retrospectively analyzed. First, to confirm that virtual ultrasonography (VUS) is an alternative method to conventional ultrasound, 22 patients underwent both conventional ultrasonography and VUS. Second, the efficacy of US quantitative methods (3-point method, 4-point method, 5-point method, and Matsumoto's method) was confirmed by VUS in 68 patients. We assessed whether the ascites volume predicted by VUS corresponded with that calculated by 3D-CT. Of the 68 patients, 23 patients were analyzed before and after administration of tolvaptan.

RESULTS

The predictive volumes calculated by VUS were remarkably relative to those yielded by conventional US. Correlations between exact volume and those measured by VUS were significantly high (3-point method: r = 0.882, p < 0.001; 4-point method: r = 0.797, p < 0.001; 5-point method: r = 0.836, p < 0.001; Matsumoto's method: r = 0.453, p < 0.001). Correlations between decreasing volume on 3D-CT and that measured by VUS were also significantly high in patients with administration of tolvaptan.

CONCLUSION

Ascites volume measured by ultrasound was effective, especially the 3-point and 5-point methods. It was useful to assess the efficacy of diuretics in cirrhotic patients.

Validation and Potential of Albumin-Bilirubin Grade and Prognostication in a Nationwide Survey of 46,681 Hepatocellular Carcinoma Patients in Japan: The Need for a More Detailed Evaluation of Hepatic Function

BACKGROUND/AIM

Recently, albumin-bilirubin (ALBI) scoring/grading, consisting of only albumin and total bilirubin, has been proposed. We examined the efficacy of this grading system for determining hepatic function in patients with hepatocellular carcinoma (HCC).

METHODS/MATERIALS

The prognoses of 46,681 HCC patients based on results obtained from a nationwide survey conducted in Japan from 2001 to 2007 were evaluated using (1) Japan Integrated Staging (JIS), consisting of Child-Pugh classification and TNM staging (TNM), (2) modified JIS (m-JIS), consisting of liver damage grading and TNM, and (3) ALBI-TNM (ALBI-T), consisting of ALBI grading and TNM, and the results were compared. A subanalysis was also performed to define a cutoff value for ALBI scores for a more detailed stratification of hepatic function.

RESULTS

ALBI-T, JIS, and m-JIS each showed good capacity for the stratification of prognoses. Although the Akaike information criterion for ALBI-T was nearly equal to that for JIS and m-JIS, the Kaplan-Meier curves and median survival times obtained with ALBI-T were always superior to the corresponding scores. When the indocyanine green retention test (<30%) was used as an additional cutoff value for ALBI score (-2.270, area under the curve 0.828) to divide ALBI grade into 4 levels (modified ALBI [mALBI] grade), mALBI grade was able to stratify the prognosis of patients at any TNM stage in order of grade. Modified ALBI-T (mALBI-T), using mALBI grading and TNM, produced a more detailed stratification for prognosis.

CONCLUSION

The predictive value for prognosis of ALBI-T was found to be equal to that of JIS and m-JIS. In addition, mALBI grading and mALBI-T, as proposed in the present study, might provide a more detailed assessment of the hepatic function and prognosis of HCC patients.

A prospective comparison between auto-registration and manual registration of real-time ultrasound with MR images for percutaneous ablation or biopsy of hepatic lesions

PURPOSE

To compare the accuracy and required time for image fusion of real-time ultrasound (US) with pre-procedural magnetic resonance (MR) images between positioning auto-registration and manual registration for percutaneous radiofrequency ablation or biopsy of hepatic lesions.

METHODS

This prospective study was approved by the institutional review board, and all patients gave written informed consent. Twenty-two patients (male/female, n = 18/n = 4; age, 61.0 ± 7.7 years) who were referred for planning US to assess the feasibility of radiofrequency ablation (n = 21) or biopsy (n = 1) for focal hepatic lesions were included. One experienced radiologist performed the two types of image fusion methods in each patient. The performance of auto-registration and manual registration was evaluated. The accuracy of the two methods, based on measuring registration error, and the time required for image fusion for both methods were recorded using in-house software and respectively compared using the Wilcoxon signed rank test.

RESULTS

Image fusion was successful in all patients. The registration error was not significantly different between the two methods (auto-registration: median, 3.75 mm; range, 1.0-15.8 mm vs. manual registration: median, 2.95 mm; range, 1.2-12.5 mm, p = 0.242). The time required for image fusion was significantly shorter with auto-registration than with manual registration (median, 28.5 s; range, 18-47 s, vs. median, 36.5 s; range, 14-105 s, p = 0.026).

CONCLUSION

Positioning auto-registration showed promising results compared with manual registration, with similar accuracy and even shorter registration time.

Comparison Between CT and MR Images as More Favorable Reference Data Sets for Fusion Imaging-Guided Radiofrequency Ablation or Biopsy of Hepatic Lesions: A Prospective Study with Focus on Patient's Respiration

PURPOSE

To identify the more accurate reference data sets for fusion imaging-guided radiofrequency ablation or biopsy of hepatic lesions between computed tomography (CT) and magnetic resonance (MR) images.

MATERIALS AND METHODS

This study was approved by the institutional review board, and written informed consent was received from all patients. Twelve consecutive patients who were referred to assess the feasibility of radiofrequency ablation or biopsy were enrolled. Automatic registration using CT and MR images was performed in each patient. Registration errors during optimal and opposite respiratory phases, time required for image fusion and number of point locks used were compared using the Wilcoxon signed-rank test.

RESULTS

The registration errors during optimal respiratory phase were not significantly different between image fusion using CT and MR images as reference data sets (p = 0.969). During opposite respiratory phase, the registration error was smaller with MR images than CT (p = 0.028). The time and the number of points locks needed for complete image fusion were not significantly different between CT and MR images (p = 0.328 and p = 0.317, respectively).

CONCLUSION

MR images would be more suitable as the reference data set for fusion imaging-guided procedures of focal hepatic lesions than CT images.

US-US Fusion Imaging in Radiofrequency Ablation for Liver Metastases

OBJECTIVE

Radiofrequency ablation (RFA) induces gas bubbles in ablation zones, and the ablative margin cannot be evaluated accurately on ultrasound (US) during and immediately after RFA. This study assessed the usefulness of US-US fusion imaging to visualize the ablative margin of RFA for liver metastasis.

METHODS

RFA guided by US-US fusion imaging was performed on 12 targeted tumors in 10 patients. Secondary hepatic malignancies included patients with colorectal cancer (n = 4), breast cancer (n = 2), lung cancer (n = 1), gastrointestinal stromal tumor (n = 1), pancreatic neuroendocrine tumor (n = 1), and adrenocortical carcinoma (n = 1). The maximal diameter of the tumors ranged from 0.8 to 4.0 cm (mean ± SD 1.6 ± 0.9 cm).

RESULTS

The mean number of electrode insertions was 1.6 per session (range 1-3). Technically, effective ablation was achieved in a single session in all patients, and safety ablative margins were confirmed on contrast-enhanced CT for early assessment of tumor response. There were no serious adverse events or procedure-related complications. During the follow-up period (median 220 days, range 31-417 days), none of the patients showed local tumor progression.

CONCLUSION

US-US fusion imaging could show the tumor images before ablation and the ablative area on US in real time. The image overlay of US-US fusion imaging made it possible to evaluate the ablative margin three dimensionally according to the US probe action. Therefore, US-US fusion imaging can contribute to RFA therapy with a safety margin, that is, the so-called precise RFA.

Assessment of a needle-tracking system for bipolar radiofrequency ablation

PURPOSE

The purpose of this study was to assess the accuracy and efficacy of a needle-tracking system in phantom and clinical studies using bipolar electrodes.

METHODS

To observe the tip of the electrode, a needle-tracking system with a volume navigation system was used. In the phantom study, the electrode was inserted at various angles and the error was verified. In the clinical study, 21 nodules close to extrahepatic organs or major vessels were enrolled between May and October 2014. After puncturing with the needle-tracking system, computed tomography (CT) was performed. The distances between the electrode tip and extrahepatic organs or major vessels were measured on both B-mode ultrasound (US) and CT. By comparing these distances, the accuracy of this system was evaluated.

RESULTS

In the phantom study, the deviation between the tip of the electrode and the virtual tip of the electrode was analyzed. The median values were within 2 mm at each puncture angle. In the clinical study, the difference between B-mode US and CT was less (mean value 1.17 ± 1.76 mm; range 0-3.5 mm).

CONCLUSION

The needle-tracking system is an accurate and useful system for bipolar radiofrequency ablation.

Initial Experience Performing Percutaneous Ultrasound Examination with Real-Time Virtual Sonography with Color Display

PURPOSE

We report the efficacy of percutaneous ultrasound (US) examination using a novel real-time virtual sonography (RVS) method that collates multiple Digital Imaging and Communications in Medicine (DICOM) data sources and displays reference images in color.

MATERIALS AND METHODS

A total of 7 patients with 9 hepatocellular carcinomas were evaluated. Using the SYNAPSE VINCENT volume analyzer, DICOM data of the portal vein, hepatic vein, tumor, and hepatic segment were isolated from contrast-enhanced computed tomography DICOM data. Each portion of DICOM data was uploaded into an US scanner (HI VISION Ascendus, Hitachi Aloka Medical Ltd., Tokyo, Japan) and unified on a US platform to create a single reference image. Each uploaded portion of DICOM data was assigned a different color. Further, conventional RVS was performed using this information.

RESULTS

The maximal tumoral diameter ranged from 6.4 to 15 mm (mean ± SD, 11.0 ± 2.8). DICOM data could be isolated, enabling the display of color RVS in all patients. Color RVS facilitated superior visibility compared with conventional grayscale RVS and facilitated the comprehension of spatial positioning.

CONCLUSION

RVS with color display demonstrates utility in increasing operator comprehension of spatial and positional relationships during percutaneous US examination.

Cost-effectiveness of navigated radiofrequency ablation for hepatocellular carcinoma in China

OBJECTIVES

Real-time virtual sonography (RVS) is a promising navigation technique for percutaneous radiofrequency ablation (RFA) treatment, especially in ablating nodules poorly visualized on conventional ultrasonography (US). However, its cost-effectiveness has not been established. The purpose of this study is to evaluate the cost-effectiveness of RVS navigated RFA (RVS-RFA) relative to US guided RFA (US-RFA) in patients with small hepatocellular carcinoma (HCC) in China, from the modified societal perspective.

METHODS

A state-transition Markov model was created using TreeAge Pro™ 2012. The parameters used in the model, including natural history of HCC patients, procedure efficacy and related costs, were obtained from a systematic search of literature through PubMed, EMBASE, and Science Citation Index databases. The simulated cohort was patients with solitary, small HCC (<3 cm in diameter) and Child-Pugh class A or B, whose tumors are poorly visualized in B-mode US but clearly detectable by CT or MRI.

RESULTS

In this cohort of difficult cases, RVS-RFA was a preferred strategy saving 2,467 CNY ($392) throughout the patient's life while gaining additional 1.4 QALYs compared with conventional US guidance. The results were sensitive to the efficacy of US-RFA and RVS-RFA including complete ablation rate and local recurrence rate, the median survival for patients with progressive HCC, the probability of performing RFA for recurrent HCC, and the cost of RVS navigation, disposable needle or hospitalization.

CONCLUSIONS

RVS-RFA is a dominant strategy for patients with small HCC unidentifiable in B-mode US, in terms of cost savings and QALYs gained, relative to the conventional US-guided method.

Virtual sonography for novice sonographers: usefulness of SYNAPSE VINCENT® with pre-check imaging of tumor location

PURPOSE

To evaluate the usefulness of a virtual ultrasound (US) imaging device as a tool to assist novice sonographers.

MATERIALS AND METHODS

A prospective blinded pilot study was conducted involving patients with liver lesions. Two sonographers and 2 medical doctors with less than 5 years of experience performed US examinations. The time needed to detect liver lesions on US and the success rate for detecting liver lesions with and without using the virtual US imaging device SYNAPSE VINCENT® (Fujifilm Medical Co., Tokyo, Japan) before US examination were evaluated.

RESULTS

Thirty-two patients with the following 42 liver lesions were included: liver cyst (n = 24), hemangioma (n = 8), hepatocellular carcinoma (n = 6), and liver metastasis (n = 4). The maximal diameter of these lesions ranged from 0.3 to 1.5 cm (mean ± SD, 0.8 ± 0.4). The average time for detecting liver lesions on US was 47.8 s (range, 7-113) with VINCENT and 112.9 s (range, 14-313) without VINCENT before US examination. There were significant differences in the duration of US examination with and without VINCENT (p = 0.0002, Student's t test). The rates for accurately detecting liver lesions were 100 and 76.2% (16/21) in US beginners with and without VINCENT, respectively. Significantly higher detection rates were found in the US beginners who used VINCENT compared to those who did not use VINCENT (p = 0.047, Fisher's exact test).

CONCLUSION

Before US examination, a reference with VINCENT could contribute to the successful detection of liver lesions and could be time-saving for US beginners.

Combination guidance of contrast-enhanced US and fusion imaging in radiofrequency ablation for hepatocellular carcinoma with poor conspicuity on contrast-enhanced US/fusion imaging

PURPOSE

The purpose of this study was to evaluate the usefulness of the combination guidance of contrast-enhanced US (CEUS) and fusion imaging in radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) with poor conspicuity on B-mode US and CEUS/fusion imaging.

MATERIALS AND METHODS

We conducted a retrospective cohort study, which included 356 patients with 556 HCCs that were inconspicuous on B-mode US. A total of 192 patients with 344 HCCs, 123 patients with 155 HCCs, and 37 patients with 57 HCCs underwent RFA under CEUS guidance, fusion imaging guidance, and the combination of CEUS and fusion imaging guidance.

RESULTS

The average number of treatment sessions was 1.1 (range: 1-2) in the CEUS guidance group, 1.1 (range: 1-2) in the fusion imaging guidance group, and 1.1 (range: 1-3) in the combination of CEUS and fusion imaging guidance group. Treatment analysis did not reveal significantly more RFA treatment sessions in the combination guidance group than in the other groups (p = 0.97, Student's t test). During the follow-up period (1.1-85.3 months, mean ± SD, 43.2 ± 59.5), the 3-year local tumor progression rates were 4.9, 7.2, and 5.9% in the CEUS guidance group, the fusion imaging guidance group, and the combination guidance group, respectively (p = 0.84, log-rank test).

CONCLUSION

In spite of selection bias, session frequency and local tumor progression were not different under the combination guidance with CEUS and fusion imaging in RFA. The combination of fusion imaging and CEUS guidance in RFA therapy is an effective treatment for HCC with poor conspicuity on B-mode US and CEUS/fusion imaging.

Ultrasound fusion imaging of hepatocellular carcinoma: a review of current evidence

With advances in technology, imaging techniques that entail fusion of sonography and CT or MRI have been introduced in clinical practice. Ultrasound fusion imaging provides CT or MRI cross-sectional multiplanar images that correspond to the sonographic images, and fusion imaging of B-mode sonography and CT or MRI can be displayed simultaneously and in real time according to the angle of the transducer. Ultrasound fusion imaging helps us understand the three-dimensional relationship between the liver vasculature and tumors, and can detect small liver tumors with poor conspicuity. This fusion imaging is attracting the attention of operators who perform radiofrequency ablation (RFA) for the treatment of hepatic malignancies because this real-time, multimodality comparison can increase monitoring and targeting confidence during the procedure. When RFA with fusion imaging was performed on small hepatocellular carcinomas (HCCs) with poor conspicuity, it was reported that the rates of technical success and local tumor progression were 94.4-100% and 0-8.3%. However, there have been no studies comparing fusion imaging guidance and contrast-enhanced sonography, CT or MRI guidance in ablation. Fusion imaging-guided RFA has proved to be effective for HCCs that are poorly defined on not only conventional B-mode sonography but also contrast-enhanced sonography. In addition, fusion imaging could be useful to assess the treatment response of RFA because of three-dimensional information. Here, we give an overview of the current status of ultrasound fusion imaging for clinical application in the liver.

Percutaneous radiofrequency ablation of malignant liver tumors with ultrasound and CT fusion imaging guidance

BACKGROUND

To evaluate the feasibility, accuracy, and utility of sonography (US) and CT fusion imaging guidance for radiofrequency ablation (RFA) of malignant liver tumors not visualized on conventional US.

METHODS

Seventy-seven patients with hepatocellular carcinoma and 15 patients with metastatic liver cancer with a total of 136 lesions underwent RFA with US and CT fusion imaging guidance. The mean number of punctures, success rate of a single ablation session, local tumor progression rates, and long-term outcome were evaluated. Treatment efficacy was evaluated by dynamic CT and contrast-enhanced US 1 month after RFA.

RESULTS

RFA was technically feasible in all patients, and no major complications occurred. The mean ± SD time needed to synchronize US and CT images was 13.9 ± 11.9 minutes (range, 5-55 minutes). The success rate of a single ablation session was 83.8% (114/136), and tumor residue was present in 7.4% of lesions (10/136). The mean number of treatment sessions was 1.2 ± 0.5 sessions. During follow-up, local tumor progression was observed for 15 (11.9%) lesions. Distant tumor recurrence was found in 51 (55.4%) patients.

CONCLUSIONS

US and CT fusion-assisted RFA is a safe and efficacious treatment for patients with hepatocellular carcinoma and metastatic liver cancer.

Fusion imaging of real-time ultrasonography with CT or MRI for hepatic intervention

With the technical development of ultrasonography (US), electromagnetic tracking-based fusion imaging of real-time US and computed tomography/magnetic resonance (CT/MR) images has been used for percutaneous hepatic intervention such as biopsy and radiofrequency ablation (RFA). Because of the fusion imaging technique, the fused CT or MR images show the same plane and move synchronously while performing real-time US. With this information, fusion imaging can enhance lesion detectability and reduce the false positive detection of focal hepatic lesions with poor sonographic conspicuity. Three-dimensional US can also be fused with realtime US for the percutaneous RFA of liver tumors requiring overlapping ablation. When fusion imaging is not sufficient for identifying small focal hepatic lesions, contrast-enhanced US can be added to fusion imaging.

Real-time US-CT/MRI image fusion for guidance of thermal ablation of liver tumors undetectable with US: results in 295 cases

PURPOSE

This study was designed to assess feasibility of US-CT/MRI fusion-guided ablation in liver tumors undetectable with US.

METHODS

From 2002 to 2012, 295 tumors (162 HCCs and 133 metastases; mean diameter 1.3 ± 0.6 cm, range 0.5-2.5 cm) detectable on contrast-enhanced CT/MRI, but completely undetectable with unenhanced US and either totally undetectable or incompletely conspicuous with contrast-enhanced US (CEUS), were treated in 215 sessions using either internally cooled radiofrequency or microwave with standard ablation protocols, guided by an image fusion system (Virtual Navigation System, Esaote S.p.A., Genova, Italy) that combines US with CT/ MRI images. Correct targeting and successful ablation of tumor were verified after 24 hours with CT or MRI.

RESULTS

A total of 282 of 295 (95.6 %) tumors were correctly targeted with successful ablation achieved in 266 of 295 (90.2 %). Sixteen of 295 (5.4 %) tumors were correctly targeted, but unsuccessfully ablated, and 13 of 295 (4.4 %) tumors were unsuccessfully ablated due to inaccurate targeting. There were no perioperative deaths. Major complications were observed in 2 of the 215 treatments sessions (0.9 %).

CONCLUSIONS

Real-time virtual navigation system with US-CT/MRI fusion imaging is precise for targeting and achieving successful ablation of target tumors undetectable with US alone. Therefore, a larger population could benefit from ultrasound guided ablation procedures.

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.

Local recurrence of hepatocellular carcinoma in the tumor blood drainage area following radiofrequency ablation

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. HCC is generally considered to spread via the bloodstream and local recurrence often occurs in the blood drainage area determined by computed tomography during hepatic arteriography (CTHA), despite complete ablation of the primary nodule. This study was conducted in order to prospectively assess the rate of local recurrence in the blood drainage area depicted by delayed-phase CTHA. The participants comprised 364 consecutive patients (260 men and 104 women; mean age, 67.4±8.6 years), enrolled between April, 2002 and December, 2011. The participants were divided into two groups, according to whether the ablation area covered the entire blood drainage area as defined by delayed-phase CTHA (group A) or not (group B). Local tumor progression was compared between the two groups. The median time to recurrence was significantly shorter for group B (434 days) compared to that for group A (1,474 days; P=0.0037). The cumulative local recurrence rates for group A were 0, 0 and 1.5% at 1, 3 and 5 years postoperatively, respectively, whereas the recurrence rates for group B were 3.8, 17.0 and 22.8% at 1, 3 and 5 years, respectively (P<0.0001). In conclusion, the safety margin for radiofrequency ablation should be defined as the blood drainage area and ablation should aim at acquiring adequate safety margins.

Percutaneous transhepatic biliary drainage assisted by real-time virtual sonography: a retrospective study

Background

Real-time virtual sonography (RVS) is a diagnostic imaging support system that can synchronize with ultrasound images in conjunction with computed tomography or magnetic resonance images using magnetic navigation system. RVS has been applied in clinical practice to perform such procedures as radiofrequency ablation and biopsy; however, the application of RVS for percutaneous transhepatic biliary drainage (PTBD) is rare.

Methods

Between 2007 and 2012, RVS-assisted PTBD was performed for 30 patients (19 males and 11 females; age range, 41 to 89 years; mean age, 66.9 years) with obstructive jaundice. The targeted bile duct was determined using the RVS system before the procedure. The intervention was considered to be successful when the targeted bile duct was punctured and the drainage catheter was placed in the bile duct. Complications were evaluated according to the Society of Interventional Radiology Clinical Practice Guidelines.

Results

A total of 37 interventions were performed for 30 patients. The interventions were successful in 35 (95%) of 37 interventions. The targeted bile ducts were: B3 (n = 24), B5 (n = 7), B8 (n = 3), B6 (n = 1), and the anterior (n = 1) and posterior (n = 1) branches of the right bile duct. The mean targeted bile duct diameter was 4.9 mm (1.9 to 8.2 mm). PTBD was able to be accomplished in all patients because the non-targeted bile ducts were successfully punctured alternatively. No major complications were observed in relation to the interventional procedure.

Conclusions

RVS-assisted PTBD is a feasible and safe procedure. Accurate puncture of targeted bile ducts can be achieved using this method.

Real-time image fusion involving diagnostic ultrasound

OBJECTIVE

The aim of our article is to give an overview of the current and future possibilities of real-time image fusion involving ultrasound. We present a review of the existing English-language peer-reviewed literature assessing this technique, which covers technical solutions (for ultrasound and endoscopic ultrasound), image fusion in several anatomic regions, and electromagnetic needle tracking.

CONCLUSION

The recent progress of real-time ultrasound in image fusion may provide several new possibilities, including diagnosis, treatment, and follow-up of oncologic patients.

The feasibility study of US-MRI virtual navigation in the shoulder

PURPOSE

The aim of this study was to evaluate the feasibility of ultrasound sonography (US)-magnetic resonance imaging (MRI) virtual navigation in the shoulder.

METHODS

We selected 10 healthy volunteers and 10 patients with supraspinatus tendinitis to fuse in the shoulder with a Virtual Navigator System. We selected five internal marks as follows: (1) ① acromion, ② the point of junction between the supraspinatus muscle and the tendon, ③ the point of the middle in the surface of the head of humerus in the plane of ②, ④ the point of attachment of the supraspinatus tendon in the great tuberosity of humerus, and ⑤ the point of the middle in the surface of the head of humerus in the plane of ④. To make three, four, and five marks in different combinations in the process of image fusion successively, it should be based on these points. The observed targets included coincidence, stability, and accuracy in the sonography and magnetic resonance images by two radiologists.

RESULTS

The supraspinatus tendon of the 10 volunteers and the lesions of 10 patients with supraspinatus tendinitis could be fused between the sonography image and the magnetic resonance image. The effect of the combination of ②+③+④+⑤ in the group with four-point internal marks was most satisfactory (P<.05).

CONCLUSION

The process of the combination of ②+③+④+⑤ in the group with four-point internal marks is considered the best method, and the application of US-MRI virtual navigation is regarded feasible in the shoulder.

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.

Oblique approach for CT-guided liver radiofrequency ablation using multiplanar reformation images in hepatocellular carcinoma

PURPOSE

To evaluate the feasibility and safety of CT-guided radiofrequency (RF) ablation by caudal-cranial oblique insertion using multiplanar reformation (MPR) images for hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Twenty-two HCCs in 19 patients that were difficult to demonstrate on ultrasound (mean tumor diameter was 17.5 mm) were treated with CT-guided RF ablation by caudal-cranial oblique insertion to avoid pneumothorax, using MPR images after transcatheter arterial chemoembolization. The insertion point and direction of insertion, avoiding aerated lung parenchyma, bones, large vessels, and intestine, were sought on the MPR images. Technical success was defined as complete eradication of tumor enhancement in the contrast-enhanced CT. Local tumor progression was defined by the appearance of enhanced tumor adjacent to the zone of ablation. The technical success rate, local tumor progression, and complications were investigated.

RESULTS

The coronal plane was used for insertion in 18 tumors, the sagittal plane in 3 tumors, and the oblique plane in 1 tumor. RF electrode placement was successful and complete necrosis was obtained in all cases. During the mean follow-up period of 38.0 months, local tumor progression was not detected in any of the patients. There were no major complications, including pneumothorax.

CONCLUSION

CT-guided RF ablation by caudal-cranial oblique insertion using MPR images is a feasible and safe therapeutic option.

Effect of CT fluoroscopy-guided transpulmonary radiofrequency ablation of liver tumours on the lung

OBJECTIVE

We retrospectively evaluated the effect of transpulmonary radiofrequency ablation (RFA) of liver tumours on the lung.

METHODS

16 patients (10 males and 6 females; mean age, 65.2 years) with 16 liver tumours (mean diameter 1.5 cm) underwent transpulmonary RFA under CT fluoroscopic guidance. The tumours were either hepatocellular carcinoma (n=14) or liver metastasis (n=12). All 16 liver tumours were undetectable with ultrasonography. The pulmonary function values at 3 months after transpulmonary RFA were compared with baseline (i.e. values before RFA).

RESULTS

In 8 of 16 sessions, minor pulmonary complications occurred, including small pneumothorax (n=8) and small pleural effusion (n=1). In two sessions, major pulmonary complications occurred, including pneumothorax requiring a chest tube (n=2). These chest tubes were removed at 4 and 6 days, and these patients were discharged 7 and 10 days after RFA, respectively, without any sequelae. The pulmonary function values we evaluated were forced expiratory volume in 1 s (FEV1.0) and vital capacity (VC). The mean values of FEV1.0 before and 3 months after RFA were 2.55 l and 2.59 l, respectively; the mean values of VC before and 3 months after RFA were 3.20 l and 3.27 l, respectively. These pulmonary values did not show any significant worsening (p=0.393 and 0.255 for FEV1.0 and VC, respectively).

CONCLUSION

There was no significant lung injury causing a fatal or intractable complication after transpulmonary RFA of liver tumours.

Efficacy of fusion imaging combining sonography and hepatobiliary phase MRI with Gd-EOB-DTPA to detect small hepatocellular carcinoma

OBJECTIVE

We evaluated the efficacy of fusion imaging that fuses conventional sonography images with hepatobiliary phase contrast-enhanced MR images obtained with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) as the reference image for the detection of hepatocellular carcinomas (HCCs).

SUBJECTS AND METHODS

Eighty-seven HCCs with a maximum diameter of between 1 and 3 cm at the time of diagnosis were enrolled in this prospective study. We compared the detection rates of HCCs using three sonography modalities: conventional sonography, late phase of contrast-enhanced sonography with Sonazoid, and fusion imaging combining conventional sonography and the hepatobiliary phase of contrast-enhanced MRI with Gd-EOB-DTPA as the reference image. The comparisons were made using the McNemar test.

RESULTS

The detection rate of HCCs using fusion imaging (98%, 85/87) was significantly higher than the detection rates using conventional sonography (76%, 66/87) and contrast-enhanced sonography (83%, 72/87) (p<0.01, for both). For small HCCs (maximum diameter, 1-2 cm), the detection rate using fusion imaging (97%, 59/61) was also significantly higher than those using conventional sonography (66%, 40/61) and contrast-enhanced sonography (80%, 49/61) (p<0.01, for both). The detection rate for atypical HCCs was also significantly higher using fusion imaging (95%, 18/19) than using conventional sonography (53%, 10/19) and contrast-enhanced sonography (26%, 5/19) (p<0.01, for both).

CONCLUSION

Fusion imaging combining conventional sonography and the hepatobiliary phase of contrast-enhanced MRI with Gd-EOB-DTPA is more sensitive than conventional sonography or contrast-enhanced sonography for detecting HCCs, especially small or atypical HCCs.

Use of fusion imaging combining contrast-enhanced ultrasonography with a perflubutane-based contrast agent and contrast-enhanced computed tomography for the evaluation of percutaneous radiofrequency ablation of hypervascular hepatocellular carcinoma

OBJECTIVE

We evaluated the efficacy of fusion imaging, which fuses contrast-enhanced ultrasonography images with arterial-phase, contrast-enhanced CT images as a reference on a single screen in real time, for the evaluation of the effectiveness of radiofrequency ablation for treatment of hypervascular hepatocellular carcinoma.

MATERIALS AND METHODS

Eighty hepatocellular carcinoma lesions with a maximum diameter of between 1 and 3 cm that were scheduled for treatment with radiofrequency ablation were enrolled in this prospective study. After bolus injection of perflubutane-based contrast agent, fusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images was performed one day after radiofrequency ablation. We used two functions, which were subsets of the fusion imaging, to confirm the location of the hepatocellular carcinoma lesions in the ablated areas and to evaluate the presence or absence of an adequate safety margin. Contrast-enhanced CT was performed one month after the ablation. Two blinded observers reviewed the images obtained using both modalities to evaluate the effect of ablation.

RESULTS

When the one-month contrast-enhanced CT images were used as the reference standard, the sensitivity, specificity, and accuracy of the one-day fusion imaging for the diagnosis of adequate ablation were 97%, 83%, and 96%, respectively; the kappa value for the agreement between the findings obtained using the two modalities was 0.75.

CONCLUSION

Fusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images as a reference appears to be a useful method for the early evaluation of the efficacy of radiofrequency ablation for the treatment of hypervascular hepatocellular carcinoma.

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.

Contrast-Enhanced Ultrasound (CEUS) for Echographic Detection of Hepato Cellular Carcinoma in Cirrhotic Patients Previously Treated with Multiple Techniques: Comparison of Conventional US, Spiral CT and 3-Dimensional CEUS with Navigator Technique (3DNav CEUS)

A commercially available technique named “NAVIGATOR” (Esaote, Italy) easily enables a 3-D reconstruction of a single 2-D acquisition of Contrast Enhanced Ultrasound (CEUS) imaging of the whole liver (with a volumetric correction thanks to the electromagnetic device of NAVIGATOR). Aim of the study was to evaluate this “panoramic” technique in comparison with conventional US and spiral CT in the detection of new hepatic lesions. 144 cirrhotic patients (previously treated for hepato cellular carcinoma (HCC)) in follow-up with detection of 98 new nodules (N), 28 multinodular (Nmulti), 14 loco-regional regrowth (LR) 94 efficaciously treated without new nodules (neg) and four multinodular without new nodules, were submitted to 200 examinations with this new technique from November 2008 to November 2009. 3DNavCEUS was performed using SonoVue (Bracco), as contrast agent, and a machine (Technos MPX, Esaote). Spiral CT and 3DNav CEUS were performed in the same month during follow up. Sens.,Spec.,diagn.-Acc.,PPV and NPV were evaluated; comparison and differences between the techniques were obtained with chi-square (SPSS release-15). Final diagnosis was: 98 new lesions (N) (one to three), 28 multinodular HCC (Nmulti) and 14 loco-regional regrowth (LR); in 94 no more lesions were observed during follow-up; conventional US obtained: 58 N (+18 multinodularN and 8 LR), 40 false negative (+10 Nmulti and 6 LR) (sens:59.2, spec:100%, Diagn Accur:73.6, PPV:100; NPV:70.1); spiral CT obtained: 84N (+26-multinodularN and 14-LR), 14 false-negative (+2-Nmulti), and one false-positive (sens:85.7, spec:97.9%, Diagn Accur:90.9, PPV:97.7; NPV:86.8); 3DNAV obtained: 92N (+28 multinodularN and 14LR), 6 false-negative, and two false-positives (sens:93.9, spec:97.9%, Diagn Accur:95.6, PPV:97.9; NPV:93.9). 3-DNav CEUS is significantly better than US and almost similar to spiral CT for detection of new HCC. This technique, in particular, showed the presence of lesions even in the cases not detected with spiral CT.

Treatment response assessment of radiofrequency ablation for hepatocellular carcinoma: usefulness of virtual CT sonography with magnetic navigation

PURPOSE

Virtual CT sonography using magnetic navigation provides cross sectional images of CT volume data corresponding to the angle of the transducer in the magnetic field in real-time. The purpose of this study was to clarify the value of this virtual CT sonography for treatment response of radiofrequency ablation for hepatocellular carcinoma.

PATIENTS AND METHODS

Sixty-one patients with 88 HCCs measuring 0.5-1.3 cm (mean±SD, 1.0±0.3 cm) were treated by radiofrequency ablation. For early treatment response, dynamic CT was performed 1-5 days (median, 2 days). We compared early treatment response between axial CT images and multi-angle CT images using virtual CT sonography.

RESULTS

Residual tumor stains on axial CT images and multi-angle CT images were detected in 11.4% (10/88) and 13.6% (12/88) after the first session of RFA, respectively (P=0.65). Two patients were diagnosed as showing hyperemia enhancement after the initial radiofrequency ablation on axial CT images and showed local tumor progression shortly because of unnoticed residual tumors. Only virtual CT sonography with magnetic navigation retrospectively showed the residual tumor as circular enhancement. In safety margin analysis, 10 patients were excluded because of residual tumors. The safety margin more than 5 mm by virtual CT sonographic images and transverse CT images were determined in 71.8% (56/78) and 82.1% (64/78), respectively (P=0.13). The safety margin should be overestimated on axial CT images in 8 nodules.

CONCLUSION

Virtual CT sonography with magnetic navigation was useful in evaluating the treatment response of radiofrequency ablation therapy for hepatocellular carcinoma.

Real-time ultrasonography-computed tomography fusion imaging for staging of hepatic metastatic involvement in patients with colorectal cancer: initial results from comparison to US seeing separate CT images and to multidetector-row CT alone

OBJECTIVES

To prospectively evaluate the role of real-time ultrasonography (US)-computed tomography (CT) fusion imaging (US-CT) in comparison with US seeing separate CT images (US + CT) and multidetector-row CT (MDCT) for the correct staging of hepatic metastatic involvement in patients with colorectal cancer.

METHODS

Sixty-four patients with newly diagnosed colorectal cancer and who were referred for abdominopelvic staging before primary tumor resection underwent same-day MDCT, US + CT, and US-CT. Examinations were evaluated on-site by 2 investigators in consensus. Investigators recorded the size and location of detected lesions on segmental liver maps, classified them as being benign, malignant, or indeterminate, and finally assessed the M stage of the liver as being M0, M1, or Mx (indeterminate). All patients underwent surgical exploration including intraoperative US. Reference standard diagnosis was based on findings at surgery, intraoperative US, histopathology, and MDCT follow-up imaging. Differences among investigated modalities were analyzed using McNemar's test.

RESULTS

The reference standard verified 109 (45 < or = 1 cm) hepatic lesions in 25 patients, including 65 (25 < or = 1 cm) metastases in 16 patients (M1). Regarding the 45 < or = 1 cm liver lesions, rates for detection were significantly higher (P < 0.05) for MDCT (80%, 36/45) and US-CT (77.8%, 35/45) than for US + CT (64.4%, 29/45); the rate for correct classification by US-CT (71.1%, 32/45) was significantly higher than for US + CT (48.9%, 22/45) and MDCT (31.1%, 14/45) (all P < 0.05). On patient-based analysis, specificity of MDCT (85.4%, 41/48) was significantly lower (P < 0.05) than for US-CT (97.9%, 47/48) and US + CT (93.7%, 45/48); the positive predictive value of MDCT (63.1%, 12/19) was not significantly different (P = 0.27) compared with US + CT (82.3%, 14/17) but significantly lower (P < 0.05) than for US-CT (93.7%, 15/16). In 13 patients (59 lesions) with only benign (stage M0) or coexistent benign and malignant lesions (stage M1), indeterminate lesion ratings and indeterminate liver stagings (Mx) occurred both significantly lower (P < 0.05) with US-CT (3.4%, 2/59; and 0%, 0/13) than with US + CT (11.9%, 7/59; and 23.1%, 3/13) or with MDCT (30.5%, 18/59; and 53.8%, 7/13).

CONCLUSIONS

Based on these initial diagnostic experiences, complementary US-CT fusion imaging of small CT-indeterminate liver lesions may have value in staging patients with colorectal cancer, focusing on patients who were likely to harbor only benign or coexisting benign and malignant liver lesions and in whom change of M staging would change the clinical management.

Percutaneous biopsy of anterior mediastinal mass guided by real-time US fused with CT

We report a case of successful fused CT-sonographic imaging-guided percutaneous biopsy of an anterior mediastinal mass, which was visualized poorly with conventional sonography. Real-time sonography fused with CT can be useful for biopsy of anterior mediastinal masses that are not well visualized on conventional sonography.

Clinical evaluation of spatial accuracy of a fusion imaging technique combining previously acquired computed tomography and real-time ultrasound for imaging of liver metastases

PURPOSE

This study was designed to evaluate the spatial accuracy of matching volumetric computed tomography (CT) data of hepatic metastases with real-time ultrasound (US) using a fusion imaging system (VNav) according to different clinical settings.

METHODS

Twenty-four patients with one hepatic tumor identified on enhanced CT and US were prospectively enrolled. A set of three landmarks markers was chosen on CT and US for image registration. US and CT images were then superimposed using the fusion imaging display mode. The difference in spatial location between the tumor visible on the CT and the US on the overlay images (reviewer #1, comment #2) was measured in the lateral, anterior-posterior, and vertical axis. The maximum difference (Dmax) was evaluated for different predictive factors. CT performed 1-30 days before registration versus immediately before. Use of general anesthesia for CT and US versus no anesthesia. Anatomic landmarks versus landmarks that include at least one nonanatomic structure, such as a cyst or a calcification

RESULTS

Overall, Dmax was 11.53 ± 8.38 mm. Dmax was 6.55 ± 7.31 mm with CT performed immediately before VNav versus 17.4 ± 5.18 with CT performed 1-30 days before (p < 0.0001). Dmax was 7.05 ± 6.95 under general anesthesia and 16.81 ± 6.77 without anesthesia (p < 0.0015). Landmarks including at least one nonanatomic structure increase Dmax of 5.2 mm (p < 0.0001). The lowest Dmax (1.9 ± 1.4 mm) was obtained when CT and VNav were performed under general anesthesia, one immediately after the other.

CONCLUSIONS

VNav is accurate when adequate clinical setup is carefully selected. Only under these conditions (reviewer #2), liver tumors not identified on US can be accurately targeted for biopsy or radiofrequency ablation using fusion imaging.