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

Microwave ablation for colorectal liver metastases with ultrasound fusion imaging assistance: a stratified analysis study based on tumor size and location

PURPOSE

To investigate the efficacy of ultrasound fusion imaging-assisted microwave ablation (MWA) for patients with colorectal liver metastases (CRLM) based on stratified analysis of tumor size and location.

METHODS

Patients with CRLM who underwent ultrasound fusion imaging-assisted MWA in our hospital between February 2020 and February 2023 were enrolled into this retrospective study. Ultrasound fusion imaging was used for detection, guidance, monitoring and immediate evaluation throughout the MWA procedures. Technical success, technique efficacy, local tumor progression (LTP), intrahepatic progression and overall survival (OS) were recorded and analyzed. The subgroup analysis of intrahepatic progression of MWA for CRLM was performed according to tumor size and location.

RESULTS

A total of 51 patients with 122 nodules were enrolled. Both technical success and technique efficacy were acquired in all nodules. In a median follow-up period of 19 months, 2.5% of the nodules (3/122) were observed LTP. The 1-year and 2-year cumulative intrahepatic progression rates were 38.7% and 52.1% respectively. Patients were divided into subgroups according to tumor size (≥ 30 mm, n = 13; < 30 mm, n = 38) and tumor location (perivascular, n = 20; non-perivascular, n = 31 and subcapsular, n = 36; non-subcapsular, n = 15). The cumulative intrahepatic progression rates were similar between the subgroups regarding tumor size and perivascular location, while significantly higher in the subcapsular group than in the non-subcapsular group (p = 0.021).

CONCLUSION

Ultrasound fusion imaging-assisted MWA exhibited satisfactory local efficacy for CRLM, especially for non-subcapsular tumors.

No-Touch Radiofrequency Ablation Using Twin Cooled Wet Electrodes for Recurrent Hepatocellular Carcinoma Following Locoregional Treatments

OBJECTIVE

To evaluate the therapeutic outcomes of no-touch radiofrequency ablation (NT-RFA) using twin cooled wet (TCW) electrodes in patients experiencing recurrent hepatocellular carcinoma (HCC) after undergoing locoregional treatments.

MATERIALS AND METHODS

We conducted a prospective, single-arm study of NT-RFA involving 102 patients, with a total of 112 recurrent HCCs (each ≤ 3 cm). NT-RFA with TCW electrodes was implemented under the guidance of ultrasonography (US)-MR/CT fusion imaging. If NT-RFA application proved technically challenging, conversion to conventional tumor puncture RFA was permitted. The primary metric for evaluation was the mid-term cumulative incidence of local tumor progression (LTP) observed post-RFA. Cumulative LTP rates were estimated using the Kaplan-Meier method. Multivariable Cox proportional hazard regression was used to explore factors associated with LTP. Considering conversion cases from NT-RFA to conventional RFA, intention-to-treat (ITT; including all patients) and per-protocol (PP; including patients not requiring conversion to conventional RFA alone) analyses were performed.

RESULTS

Conversion from NT-RFA to conventional RFA was necessary for 24 (21.4%) out of 112 tumors. Successful treatment was noted in 111 (99.1%) out of them. No major complications were reported among the patients. According to ITT analysis, the estimated cumulative incidences of LTP were 1.9%, 6.0%, and 6.0% at 1, 2, and 3 years post-RFA, respectively. In PP analysis, the cumulative incidence of LTP was 0.0%, 1.3%, and 1.3% at 1, 2, and 3 years, respectively. The number of previous locoregional HCC treatments (adjusted hazard ratio [aHR], 1.265 per 1 treatment increase; P = 0.004), total bilirubin (aHR, 7.477 per 1 mg/dL increase; P = 0.012), and safety margin ≤ 5 mm (aHR, 9.029; P = 0.016) were independently associated with LTP in ITT analysis.

CONCLUSION

NT-RFA using TCW electrodes is a safe and effective treatment for recurrent HCC, with 6.0% (ITT analysis) and 1.3% (PP analysis) cumulative incidence of LTP at 2 and 3-year follow-ups.

Computer-modified paramedian approach technique reduces failures and alleviates pain in lumbar puncture: a prospective comparative study

Background

The conventional midline approach for lumbar puncture (MAT-LP) has a relatively low success rate of 70%. The paramedian approach can increase the effective puncture area and success rate but lacks standardized guidelines. This study evaluated a computer-modified paramedian approach technique (CMPAT) to optimize lumbar puncture using computational techniques.

Methods

In this prospective study, 120 patients underwent CMPAT-LP (n = 60) or MAT-LP (n = 60). Puncture failure was defined after 6 attempts. Failure rate, number of attempts, pain score, and complications were compared. Subgroup analysis was conducted for age (≥ 50 years).

Results

No significant demographic differences existed between groups. Failure rates were 3.3% for CMPAT vs. 13.3% for MAT. Puncture attempts averaged 2.0 vs. 3.5 and pain scores were 2.7 vs. 4.1 for CMPAT and MAT, respectively. All outcomes were significantly improved with CMPAT, especially in elderly patients. No significant difference in complications was observed.

Conclusion

Compared to MAT, CMPAT-LP demonstrated lower failure rates, fewer puncture attempts, and less pain, without compromising safety. CMPAT may be superior and should be more widely implemented in clinical practice.

Utility of fusion imaging for the evaluation of ultrasound quality in hepatocellular carcinoma surveillance

PURPOSE

This study evaluated the quality of surveillance ultrasound (US) for hepatocellular carcinoma (HCC) utilizing fusion imaging.

METHODS

This research involved a secondary analysis of a prospectively recruited cohort. Under institutional review board approval, participants referred for surveillance US who had undergone liver computed tomography (CT) or magnetic resonance imaging (MRI) within the past year were screened between August 2022 and January 2023. After patient consent was obtained, the US visualization score in the Liver Imaging Reporting and Data System was assessed with fusion imaging at the time of examination. This score was compared to that of conventional US using the extended McNemar test. Multivariable logistic regression analysis was used to identify factors independently associated with a US visualization score of B or C. Factors limiting visualization of focal lesions were recorded during fusion imaging.

RESULTS

Among the 105 participants (mean age, 59±11 years; 66 men), US visualization scores of B and C were assigned to 57 (54.3%) and 17 (16.2%) participants, respectively, by conventional US and 54 (51.4%) and 32 (30.5%) participants, respectively, by fusion imaging. The score distribution differed significantly between methods (P=0.010). Male sex was independently associated with US visualization scores of B or C (adjusted odds ratio, 3.73 [95% confidence interval, 1.30 to 10.76]; P=0.015). The most common reason (64.5%) for lesion nondetection was a limited sonic window.

CONCLUSION

Conventional US may underestimate the limitations of the sonic window relative to real-time fusion imaging with pre-acquired CT or MRI in the surveillance of HCC.

A robust and automatic CT-3D ultrasound registration method based on segmentation, context, and edge hybrid metric

BACKGROUND

The fusion of computed tomography (CT) and ultrasound (US) image can enhance lesion detection ability and improve the success rate of liver interventional radiology. The image-based fusion methods encounter the challenge of registration initialization due to the random scanning pose and limited field of view of US. Existing automatic methods those used vessel geometric information and intensity-based metric are sensitive to parameters and have low success rate. The learning-based methods require a large number of registered datasets for training.

PURPOSE

The aim of this study is to provide a fully automatic and robust US-3D CT registration method without registered training data and user-specified parameters assisted by the revolutionary deep learning-based segmentation, which can further be used for preparing training samples for the study of learning-based methods.

METHODS

We propose a fully automatic CT-3D US registration method by two improved registration metrics. We propose to use 3D U-Net-based multi-organ segmentation of US and CT to assist the conventional registration. The rigid transform is searched in the space of any paired vessel bifurcation planes where the best transform is decided by a segmentation overlap metric, which is more related to the segmentation precision than Dice coefficient. In nonrigid registration phase, we propose a hybrid context and edge based image similarity metric with a simple mask that can remove most noisy US voxels to guide the B-spline transform registration. We evaluate our method on 42 paired CT-3D US datasets scanned with two different US devices from two hospitals. We compared our methods with other exsiting methods with both quantitative measures of target registration error (TRE) and the Jacobian determinent with paired t-test and qualitative registration imaging results.

RESULTS

The results show that our method achieves fully automatic rigid registration TRE of 4.895 mm, deformable registration TRE of 2.995 mm in average, which outperforms state-of-the-art automatic linear methods and nonlinear registration metrics with paired t-test's p value less than 0.05. The proposed overlap metric achieves better results than self similarity description (SSD), edge matching (EM), and block matching (BM) with p values of 1.624E-10, 4.235E-9, and 0.002, respectively. The proposed hybrid edge and context-based metric outperforms context-only, edge-only, and intensity statistics-only-based metrics with p values of 0.023, 3.81E-5, and 1.38E-15, respectively. The 3D US segmentation has achieved mean Dice similarity coefficient (DSC) of 0.799, 0.724, 0.788, and precision of 0.871, 0.769, 0.862 for gallbladder, vessel, and branch vessel, respectively.

CONCLUSIONS

The deep learning-based US segmentation can achieve satisfied result to assist robust conventional rigid registration. The Dice similarity coefficient-based metrics, hybrid context, and edge image similarity metric contribute to robust and accurate registration.

Image Fusion Technology in Interventional Radiology

Image fusion technology aims to improve patient outcomes for image-guided interventions by leveraging the strengths of multimodality imaging datasets. This most commonly involves the overlay or co-display of advanced cross-sectional imaging permitting freedom of device placement via conventional image guidance such as ultrasound, fluoroscopy, and computed tomography. This can allow the interventionalist to target and treat lesions that would otherwise be difficult or impossible to visualize and access using conventional imaging guidance. Furthermore, the use of image fusion can allow for procedures traditionally performed with cross-sectional imaging to be performed under ultrasound or fluoroscopy, by importing the data from preacquired cross-sectional imaging into the interventional procedure. This manuscript provides an overview of image fusion technologies used for interventional radiology (IR) guidance, with an emphasis on technical considerations.

Anatomical ablation for small hepatocellular carcinomas using multiple applicators: a preliminary study

BACKGROUND

Anatomical ablation, defined as thermal ablation of tumor-bearing small portal territories, may provide excellent local tumor control in peripherally-located small hepatocellular carcinomas (HCC), which has been a major concern with percutaneous ablation alone.

PURPOSE

To evaluate the technical feasibility and therapeutic outcomes of anatomical ablation using multiple radiofrequency (RF) applicators for the ablation of tumor-bearing small portal territories of peripherally-located small (≤ 4 cm) HCCs.

MATERIALS AND METHODS

Patients with peripherally-located single HCCs (≤ 4 cm) to be treated with anatomical ablation using multiple RF applicators between January 2020 and March 2022 were enrolled in this prospective study. Anatomical ablation was performed for the index tumor under real-time US-CT/MR fusion imaging guidance, with one or two clustered electrode needles placed across the tumor-bearing portal vein branches. Technical success and complications of anatomical ablations were assessed. Cumulative incidence of local tumor progression (LTP) and recurrence-free survival were estimated using the Kaplan-Meier method.

RESULTS

Fifty-five HCCs (mean size, 1.77 ± 0.59 cm) in 55 participants (mean age, 66.4 ± 7.7 years; 39 men, 16 women) were treated with anatomical ablation; 98.2% (54/55) technical success was achieved. No major complications were noted. Among the 55 participants, LTP occurred in only one patient who had experienced technical failure of anatomical ablation. Estimated 1- and 2-year cumulative incidences of LTP were 0% and 3.7%, respectively. Five patients developed intrahepatic remote recurrence during the median follow-up period of 19.2 months (range, 3.7-28.8 months); therefore, estimated 1- and 2-year recurrence-free survival was 91.7% and 85.0%, respectively.

CONCLUSION

Anatomical ablation using multiple RF applicators provided the excellent results of local tumor control in patients with peripherally-located small (≤ 4 cm) HCCs.

TRIAL REGISTRATION

clinicaltrial.gov identifier: NCT05397860.

No-Touch Radiofrequency Ablation for Early Hepatocellular Carcinoma: 2023 Korean Society of Image-Guided Tumor Ablation Guidelines

Radiofrequency ablation (RFA) has been widely used to manage hepatocellular carcinomas (HCCs) equal to or smaller than 3 cm. No-touch RFA has gained attention and has recently been implemented in local ablation therapy for HCCs, despite its technical complexity, as it provides improved local tumor control compared to conventional tumor-puncturing RFA. This article presents the practice guidelines for performing no-touch RFA for HCCs, which have been endorsed by the Korean Society of Image-Guided Tumor Ablation (KSITA). The guidelines are primarily designed to assist interventional oncologists and address the limitations of conventional tumor-puncturing RFA with describing the fundamental principles, various energy delivery methods, and clinical outcomes of no-touch RFA. The clinical outcomes include technical feasibility, local tumor progression rates, survival outcomes, and potential complications.

Treatment Outcomes of Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: Effects of the Electrode Type and Placement Method

OBJECTIVE

To investigate the association among the electrode placement method, electrode type, and local tumor progression (LTP) following percutaneous radiofrequency ablation (RFA) for small hepatocellular carcinomas (HCCs) and to assess the risk factors for LTP.

MATERIALS AND METHODS

In this retrospective study, we enrolled 211 patients, including 150 males and 61 females, who had undergone ultrasound-guided RFA for a single HCC < 3 cm. Patients were divided into four combination groups of the electrode type and placement method: 1) tumor-puncturing with an internally cooled tip (ICT), 2) tumor-puncturing with an internally cooled wet tip (ICWT), 3) no-touch with ICT, and 4) no-touch with ICWT. Univariable and multivariable Cox proportional-hazards regression analyses were performed to evaluate the risk factors for LTP. The major RFA-related complications were assessed.

RESULTS

Overall, 83, 34, 80, and 14 patients were included in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. The cumulative LTP rates differed significantly among the four groups. Compared to tumor puncturing with ICT, tumor puncturing with ICWT was associated with a lower LTP risk (adjusted hazard ratio [aHR] = 0.11, 95% confidence interval [CI] = 0-0.88, P = 0.034). However, the cumulative LTP rate did not differ significantly between tumor-puncturing with ICT and no-touch RFA with ICT (aHR = 0.34, 95% CI = 0.03-1.62, P = 0.188) or ICWT (aHR = 0.28, 95% CI = 0-2.28, P = 0.294). An insufficient ablative margin was a risk factor for LTP (aHR = 6.13, 95% CI = 1.41-22.49, P = 0.019). The major complication rates were 1.2%, 0%, 2.5%, and 21.4% in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively.

CONCLUSION

ICWT was associated with a lower LTP rate compared to ICT when performing tumor-puncturing RFA. An insufficient ablation margin was a risk factor for LTP.

A review of MRI (CT)/US fusion imaging in treatment of breast cancer

The ultrasound fusion imaging system is a diagnostic device developed in Japan that utilizes ultrasound and magnetic positioning/navigation. A position sensor with a probe reads spatial location information from a magnetic field generator and by synchronously displaying ultrasound images and magnetic resonance (MR)/computed tomography (CT) images in real time. Lesions that are difficult to observe via ultrasonography alone, such as non-mass enhancement, can be identified. Furthermore, lesions that are difficult to identify with ultrasound alone indicated for MRI-guided biopsy under the National Health Insurance Scheme can be identified using ultrasound fusion technology, thereby enabling tissue biopsy to be performed under ultrasound guidance. Using this ultrasound fusion technology, not only non-mass enhancement but also small lesions that are difficult to identify using ultrasound alone can be detected, thus ensuring that a more accurate preoperative imaging diagnosis is established, and leading to safer, more reassuring examinations and surgical procedures. In this paper, we outline the use of this ultrasound fusion technology and fusion techniques in the treatment of breast cancer.

Application of Intraoperative CT-Ultrasound Fusion Imaging in Hip Endoscopy for Treatment of Iatrogenic Impingement Due to PLLA Screw: A Novel Surgical Technique

Ultrasound-assisted surgery is becoming an established tool in the medical field. The addition of imagery to ultrasound-assisted surgery may enable one to perform a procedure in a safer and more accurate manner. This can be achieved through fusion imaging (fusion), a technology that synchronizes MRI or CT images with ultrasound images. We describe intraoperative CT-ultrasound fusion-guided (or -assisted) hip endoscopy for the removal of an impinging poly L-lactic acid screw, which was difficult to identify on fluoroscopy during surgery. The fusion technology enables merging two advantages of ultrasound: the real-time guidance capabilities and CT or MRI and the bird's eye view that makes minimally invasive arthroscopic and endoscopic surgery less invasive, precise, and safe.

Ultrasound Fusion: Applications in Musculoskeletal Imaging

Ultrasound fusion is an established technique that pairs real time B-scan ultrasound (US) with other forms of cross-sectional imaging, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Each of these imaging modalities has distinct advantages. CT provides superior anatomic resolution, with improved imaging of bone and calcified structures; MRI has superior contrast resolution; and PET provides physiologic information, identifying processes that are metabolically active (i.e., tumor, inflammatory conditions). However, these modalities are static. A key highlight of ultrasound is its capability of dynamic, real-time scanning. The ability to pair CT, MRI or PET with ultrasound can have significant advantages, both in diagnostic evaluation and when performing difficult or challenging image-guided interventions. Percutaneous interventions using ultrasound fusion have been described in the abdominal imaging literature; however, there have been very few musculoskeletal applications detailed in the literature. The purpose of this article is to review the basic concepts of real-time ultrasound fusion, and to detail, through the use of multiple case examples, its potential use as a safe and effective method for performing image-guided musculoskeletal interventions.

Efficacy of fusion imaging for immediate post-ablation assessment of malignant liver neoplasms: A systematic review

BACKGROUND

Percutaneous thermal ablation has become the preferred therapeutic treatment option for liver cancers that cannot be resected. Since ablative zone tissue changes over time, it becomes challenging to determine therapy effectiveness over an extended period. Thus, an immediate post-procedural evaluation of the ablation zone is crucial, as it could influence the need for a second-look treatment or follow-up plan. Assessing treatment response immediately after ablation is essential to attain favorable outcomes. This study examines the efficacy of image fusion strategies immediately post-ablation in liver neoplasms to determine therapeutic response.

METHODOLOGY

A comprehensive systematic search using PRISMA methodology was conducted using EMBASE, MEDLINE (via PUBMED), and Cochrane Library Central Registry electronic databases to identify articles that assessed the immediate post-ablation response in malignant hepatic tumors with fusion imaging (FI) systems. The data were retrieved on relevant clinical characteristics, including population demographics, pre-intervention clinical history, lesion characteristics, and intervention type. For the outcome metrics, variables such as average fusion time, intervention metrics, technical success rate, ablative safety margin, supplementary ablation rate, technical efficacy rate, LTP rates, and reported complications were extracted.

RESULTS

Twenty-two studies were included for review after fulfilling the study eligibility criteria. FI's immediate technical success rate ranged from 81.3% to 100% in 17/22 studies. In 16/22 studies, the ablative safety margin was assessed immediately after ablation. Supplementary ablation was performed in 9 studies following immediate evaluation by FI. In 15/22 studies, the technical effectiveness rates during the first follow-up varied from 89.3% to 100%.

CONCLUSION

Based on the studies included, we found that FI can accurately determine the immediate therapeutic response in liver cancer ablation image fusion and could be a feasible intraprocedural tool for determining short-term post-ablation outcomes in unresectable liver neoplasms. There are some technical challenges that limit the widespread adoption of FI techniques. Large-scale randomized trials are warranted to improve on existing protocols. Future research should emphasize improving FI's technological capabilities and clinical applicability to a broader range of tumor types and ablation procedures.

Multimodal registration of ultrasound and MR images using weighted self-similarity structure vector

PROPOSE

Multimodal registration of 2D Ultrasound (US) and 3D Magnetic Resonance (MR) for fusion navigation can improve the intraoperative detection accuracy of lesion. However, multimodal registration remains a challenge because of the poor US image quality. In the study, a weighted self-similarity structure vector (WSSV) is proposed to registrate multimodal images.

METHOD

The self-similarity structure vector utilizes the normalized distance of symmetrically located patches in the neighborhood to describe the local structure information. The texture weights are extracted using the local standard deviation to reduce the speckle interference in the US images. The multimodal similarity metric is constructed by combining a self-similarity structure vector with a texture weight map.

RESULTS

Experiments were performed on US and MR images of the liver from 88 groups of data including 8 patients and 80 simulated samples. The average target registration error was reduced from 14.91 ± 3.86 mm to 4.95 ± 2.23 mm using the WSSV-based method.

CONCLUSIONS

The experimental results show that the WSSV-based registration method could robustly align the US and MR images of the liver. With further acceleration, the registration framework can be potentially applied in time-sensitive clinical settings, such as US-MR image registration in image-guided surgery.

A hybrid deformable registration method to generate motion-compensated 3D virtual MRI for fusion with interventional real-time 3D ultrasound

PURPOSE

Ultrasound is often the preferred modality for image-guided therapy or treatment in organs such as liver due to real-time imaging capabilities. However, the reduced conspicuity of tumors in ultrasound images adversely impacts the precision and accuracy of treatment delivery. This problem is compounded by deformable motion due to breathing and other physiological activity. This creates the need for a fusion method to align interventional US with pre-interventional modalities that provide superior soft-tissue contrast (e.g., MRI) to accurately target a structure-of-interest and compensate for liver motion.

METHOD

In this work, we developed a hybrid deformable fusion method to align 3D pre-interventional MRI and 3D interventional US volumes to target the structures-of-interest in liver accurately in real-time. The deformable multimodal fusion method involved an offline alignment of a pre-intervention MRI with a pre-intervention US volume using a traditional registration method, followed by real-time prediction of deformation using a trained deep-learning model between interventional US volumes across different respiratory states. This framework enables motion-compensated MRI-US image fusion in real-time for image-guided treatment.

RESULTS

The proposed hybrid deformable registration method was evaluated on three healthy volunteers across the pre-intervention MRI and 20 US volume pairs in the free-breathing respiratory cycle. The mean Euclidean landmark distance of three homologous targets in all three volunteers was less than 3 mm for percutaneous liver procedures.

CONCLUSIONS

Preliminary results show that clinically acceptable registration accuracies for near real-time, deformable MRI-US fusion can be achieved by our proposed hybrid approach. The proposed combination of traditional and deep-learning deformable registration techniques is thus a promising approach for motion-compensated MRI-US fusion to improve targeting in image-guided liver interventions.

Percutaneous radiofrequency ablation of hepatocellular carcinoma in a recent cohort at a tertiary cancer center: incidence and factors associated with major complications and unexpected hospitalization events

PURPOSE

This study aimed to assess the incidence of and factors associated with major complications, delayed discharge, and emergency room (ER) visits or readmission after percutaneous radiofrequency ablation (RFA) for single hepatocellular carcinoma (HCC) <3 cm in a recent cohort at a tertiary cancer center.

METHODS

A total of 188 patients with treatment-naïve single HCCs <3 cm who underwent RFA between January 2018 and April 2021 were included in the analysis. Univariable and multivariable logistic regression analyses were performed to identify the factors associated with major complications, delayed discharge, and ER visits or readmission. Local tumor progression (LTP) and overall survival were estimated using the Kaplan-Meier method and Cox proportional-hazards regression analysis.

RESULTS

Major complications occurred in 3.2% (6/188) of the patients. The longest diameter of the ablation zone was significantly larger in patients with major complications (P=0.023). Delayed discharge occurred in 5.8% (9/188) of the patients, for which albumin-bilirubin grade 3 was identified as an important determinant. No variables other than major complications were significantly associated with ER visits or readmission, which occurred in 7.0% (13/188) of the patients. Major complications, delayed discharge, and ER visits or readmission were not substantially related to the post-treatment outcomes of LTP and overall survival.

CONCLUSION

This study confirmed RFA as a highly safe procedure for single HCCs <3 cm, despite the rapidly changing RFA techniques in the most recent cohort. A large ablation zone and poor liver function were predictors of major complications and delayed discharge, respectively.

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.

Recent Advances in Tracking Devices for Biomedical Ultrasound Imaging Applications

With the rapid advancement of tracking technologies, the applications of tracking systems in ultrasound imaging have expanded across a wide range of fields. In this review article, we discuss the basic tracking principles, system components, performance analyses, as well as the main sources of error for popular tracking technologies that are utilized in ultrasound imaging. In light of the growing demand for object tracking, this article explores both the potential and challenges associated with different tracking technologies applied to various ultrasound imaging applications, including freehand 3D ultrasound imaging, ultrasound image fusion, ultrasound-guided intervention and treatment. Recent development in tracking technology has led to increased accuracy and intuitiveness of ultrasound imaging and navigation with less reliance on operator skills, thereby benefiting the medical diagnosis and treatment. Although commercially available tracking systems are capable of achieving sub-millimeter resolution for positional tracking and sub-degree resolution for orientational tracking, such systems are subject to a number of disadvantages, including high costs and time-consuming calibration procedures. While some emerging tracking technologies are still in the research stage, their potentials have been demonstrated in terms of the compactness, light weight, and easy integration with existing standard or portable ultrasound machines.

A review on treatments of hepatocellular carcinoma—role of radio wave ablation and possible improvements

Background

Currently, several treatment options are available for liver cancer depending on various factors such as location, size, shape, and liver function. Image fusion is required for the diagnosis, intervention, and follow-up of certain HCCs. Presently, mental fusion is the only way while diagnosing liver lesions by comparing the ultrasound (US) image with the computed tomography (CT) image. Nevertheless, mental fusion is bound to have errors. The objective of this paper is to study the present treatment options for hepatocellular carcinoma and review the present treatment options, list out their potential limitations, and present a possible alternative solution based on the findings to reduce errors and mistargeting.

Methods

This is a systematic review on the present treatment options for hepatocellular carcinoma, especially radio wave ablation.

Results

It is found that computer fusion is the possible alternative to the present mental registration.

Conclusions

Although computer fusion is the best alternative to use radio wave ablation, there have been a few open-ended questions to further explore.

Percutaneous radiofrequency ablation of solitary hepatic metastasis from colorectal cancer: Risk factors of local tumor progression-free survival and overall survival

Purpose

This study aimed to evaluate local tumor progression-free survival (LTPFS) and overall survival (OS) after percutaneous radiofrequency ablation (RFA) for solitary colorectal liver metastases (CLM) <3 cm and to identify the risk factors associated with poor LTPFS and OS after percutaneous RFA.

Methods

This study screened 219 patients who underwent percutaneous RFA for CLM between January 2013 and November 2020. Of these, 92 patients with a single CLM <3 cm were included. LTPFS and OS were calculated using the Kaplan-Meier method, and the differences between curves were compared using the log-rank test. Risk factors for LTPFS and OS were assessed using Cox proportional-hazard regression models.

Results

Technical efficacy was achieved in the first (n=91) or second (n=1) RFA sessions. During the follow-up (median, 20.0 months), cumulative LTPFS rates at 1, 3, and 5 years were 92.4%, 83.4%, and 76.5%, respectively. During the follow-up (median, 27.8 months), the corresponding OS rates were 97.5%, 81.3%, and 74.8%, respectively. In multivariable Cox regression analyses, the group with both tumor-puncturing RFA and a T4 stage primary tumor (hazard ratio, 3.3; 95% confidence interval, 1.1 to 10.2; P=0.037) had poor LTPFS. In the univariable analysis, no factors were significantly associated with poor OS.

Conclusion

Both LTPFS and OS were promising after percutaneous RFA for a single CLM <3 cm. The group with both tumor-puncturing RFA and a T4 stage primary tumor showed poor LTPFS. No risk factors were identified for poor OS.

Decision fusion in healthcare and medicine: a narrative review

OBJECTIVE

To provide an overview of the decision fusion (DF) technique and describe the applications of the technique in healthcare and medicine at prevention, diagnosis, treatment and administrative levels.

BACKGROUND

The rapid development of technology over the past 20 years has led to an explosion in data growth in various industries, like healthcare. Big data analysis within the healthcare systems is essential for arriving to a value-based decision over a period of time. Diversity and uncertainty in big data analytics have made it impossible to analyze data by using conventional data mining techniques and thus alternative solutions are required. DF is a form of data fusion techniques that could increase the accuracy of diagnosis and facilitate interpretation, summarization and sharing of information.

METHODS

We conducted a review of articles published between January 1980 and December 2020 from various databases such as Google Scholar, IEEE, PubMed, Science Direct, Scopus and web of science using the keywords decision fusion (DF), information fusion, healthcare, medicine and big data. A total of 141 articles were included in this narrative review.

CONCLUSIONS

Given the importance of big data analysis in reducing costs and improving the quality of healthcare; along with the potential role of DF in big data analysis, it is recommended to know the full potential of this technique including the advantages, challenges and applications of the technique before its use. Future studies should focus on describing the methodology and types of data used for its applications within the healthcare sector.

Operator Evaluation of Ultrasound Fusion Imaging Usefulness in the Percutaneous Ablation of Hepatic Malignancies: A Prospective Study

The purpose of the work described here was to evaluate the use of ultrasound fusion imaging (US-FI) in percutaneous ablation of hepatic malignancies with respect to its global usefulness, improvement of conspicuity, confidence increment, needle route changes, and time savings. Thirty-four hepatic tumors (28 hepatocellular carcinomas, 6 metastases) were prospectively ablated in 16 consecutive patients (64 ± 11 y, 75% males), first simulating B-mode-only planning and then synchronizing computed tomography/magnetic resonance images with US and proceeding to needle insertion and tumor ablation under US-FI guidance. Surveys were administered to the operators to evaluate their perception of US-FI advantages. First treatment and local recurrence were also compared. US-FI was judged useful in 91% of cases and more useful when the tumor was not conspicuous in B-mode (p < 0.001), in particular for ablation of local recurrences (p = 0.021). Forty-one percent of tumors were undetectable at B-mode evaluation, and 93% of them were completely ablated under US-FI guidance. The confidence of the operator was highly increased by US-FI in 68% of cases. In 71% of cases, the radiologist saved time using US-FI, especially in treatment of local recurrences (p = 0.024). In conclusion, US-FI significantly increases the detection of target tumors, improves the confidence of the operator and is a time-saving method, especially in the treatment of local recurrences.

No-Touch vs. Conventional Radiofrequency Ablation Using Twin Internally Cooled Wet Electrodes for Small Hepatocellular Carcinomas: A Randomized Prospective Comparative Study

Objective

This study aimed to compare the efficacy between no-touch (NT) radiofrequency ablation (RFA) and conventional RFA using twin internally cooled wet (TICW) electrodes in the bipolar mode for the treatment of small hepatocellular carcinomas (HCC).

Materials and Methods

In this single-center, two-arm, parallel-group, prospective randomized controlled study, we performed a 1:1 random allocation of eligible patients with HCCs to receive NT-RFA or conventional RFA between October 2016 and September 2018. The primary endpoint was the cumulative local tumor progression (LTP) rate after RFA. Secondary endpoints included technical conversion rates of NT-RFA, intrahepatic distance recurrence, extrahepatic metastasis, technical parameters, technical efficacy, and rates of complications. Cumulative LTP rates were analyzed using Kaplan-Meier analysis and the Cox proportional hazard regression model. Considering conversion cases from NT-RFA to conventional RFA, intention-to-treat and as-treated analyses were performed.

Results

Enrolled patients were randomly assigned to the NT-RFA group (37 patients with 38 HCCs) or the conventional RFA group (36 patients with 38 HCCs). Among the NT-RFA group patients, conversion to conventional RFA occurred in four patients (10.8%, 4/37). According to intention-to-treat analysis, both 1- and 3-year cumulative LTP rates were 5.6%, in the NT-RFA group, and they were 11.8% and 21.3%, respectively, in the conventional RFA group (p = 0.073, log-rank). In the as-treated analysis, LTP rates at 1 year and 3 years were 0% and 0%, respectively, in the NT-RFA group sand 15.6% and 24.5%, respectively, in the conventional RFA group (p = 0.004, log-rank). In as-treated analysis using multivariable Cox regression analysis, RFA type was the only significant predictive factor for LTP (hazard ratio = 0.061 with conventional RFA as the reference, 95% confidence interval = 0.000–0.497; p = 0.004). There were no significant differences in the procedure characteristics between the two groups. No procedure-related deaths or major complications were observed.

Conclusion

NT-RFA using TICW electrodes in bipolar mode demonstrated significantly lower cumulative LTP rates than conventional RFA for small HCCs, which warrants a larger study for further confirmation.

New frontiers in liver ultrasound: From mono to multi parametricity

Modern liver ultrasonography (US) has become a “one-stop shop” able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic for the detection and characterization of focal liver lesions. Ultrasound can be used to guide loco-regional treatment of liver malignancies and to assess tumoral response either to interventional procedures or medical therapies. Microbubbles may also carry and deliver drugs under ultrasound exposure. US plays a crucial role in diagnosing, treating and monitoring focal and diffuse liver disease. On the basis of personal experience and literature data, this paper is aimed to review the main topics involving recent advances in the field of liver ultrasound.

Fusion imaging-guided radiofrequency ablation for residual hepatocellular carcinoma invisible on ultrasound after transcatheter arterial chemoembolization

PURPOSE

This study aimed to investigate the technical efficiency and therapeutic response of fusion imaging (considered as virtual navigation) between contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography/magnetic resonance imaging (CECT/CEMRI) for the guidance of radiofrequency ablation (RFA) in patients with residual hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE).

METHODS

For this prospective study, 98 patients with residual HCC lesions after TACE treatment were enrolled between June 2017 and December 2020. All the lesions were invisible on conventional ultrasound scans. Percutaneous RFA was performed using either CEUS (CEUS group, 52 lesions) or virtual navigation (VN group, 46 lesions) guidance. The lesion display rate, disease-free survival rate, local recurrence rate, overall survival rate and complication incidence were calculated and compared.

RESULTS

Fusion imaging had a significant impact on the RFA outcomes (hazard ratio, 2.629; 95% confidence interval, 1.256-5.505; p = .01). The median disease-free survival time of the VN group was significantly higher than that of the CEUS group (10.9 vs. 8.8 months; p = .007). The local recurrence rates after 3, 6 and 12 months in the VN group were significantly lower than those in the CEUS group (p = .014, .002 and .011). The minor complication rate was not significantly different between the two groups.

CONCLUSIONS

CEUS-CECT/CEMRI fusion imaging for guiding RFA enables an efficient and useful therapy of inconspicuous HCC lesions after TACE. The novel solution prolongs the disease-free survival time and reduces the long-term local recurrence of residual lesions treated when using virtual-navigation (VN)-guided RFA.

Differential Imaging of Liver Tumors before and after Microwave Ablation with Electrode Displacement Elastography

Liver cancer is a leading cause of cancer-related deaths; however, primary treatment options such as surgical resection and liver transplant may not be viable for many patients. Minimally invasive image-guided microwave ablation (MWA) provides a locally effective treatment option for these patients with an impact comparable to that of surgery for both cancer-specific and overall survival. MWA efficacy is correlated with accurate image guidance; however, conventional modalities such as B-mode ultrasound and computed tomography have limitations. Alternatively, ultrasound elastography has been used to demarcate post-ablation zones, yet has limitations for pre-ablation visualization because of variability in strain contrast between cancer types. This study attempted to characterize both pre-ablation tumors and post-ablation zones using electrode displacement elastography (EDE) for 13 patients with hepatocellular carcinoma or liver metastasis. Typically, MWA ablation margins of 0.5-1.0 cm are desired, which are strongly correlated with treatment efficacy. Our results revealed an average estimated ablation margin inner quartile range of 0.54-1.21 cm with a median value of 0.84 cm. These treatment margins lie within or above the targeted ablative margin, indicating the potential to use EDE for differentiating index tumors and ablated zones during clinical ablations. We also obtained a high correlation between corresponding segmented cross-sectional areas from contrast-enhanced computed tomography, the current clinical gold standard, when compared with EDE strain images, with r2 values of 0.97 and 0.98 for pre- and post-ablation regions.

Outcome of No-Touch Radiofrequency Ablation for Small Hepatocellular Carcinoma: A Multicenter Clinical Trial

Background Recently introduced no-touch radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) has the potential to improve local tumor control. Purpose To evaluate midterm clinical outcomes of monopolar no-touch RFA in single HCCs 2.5 cm or smaller. Materials and Methods In this multicenter clinical trial (ClinicalTrials.gov: NCT03375281), participants were evaluated for eligibility from November 2017 to January 2019. Patients with single HCCs 2.5 cm or smaller planning to be treated with no-touch RFA were enrolled. The rate of successful no-touch RFA, defined as performing RFA without violation of the tumor itself, was recorded. Multivariable logistic regression analysis was used to determine associated factors for failure of no-touch RFA. Development of major complication after no-touch RFA was also recorded. Cumulative incidence of local tumor progression (LTP) and recurrence-free survival were estimated by using the Kaplan-Meier method. Results A total of 140 participants (mean age, 62 years ± 9 [standard deviation]; 106 men) were evaluated. No-touch RFA was successfully performed in 128 participants (128 of 140; 91.4%), and conversion to tumor puncture RFA was undertaken in 12 participants because of the lack of a safe access route. By using either no-touch RFA or conversion to tumor puncture RFA, all participants achieved technical success of RFA, which was defined as complete coverage of target tumor by ablation zone. Insufficient peritumoral parenchyma (<5 mm width around more than half portion of tumor; odds ratio, 74; 95% CI: 18, 309; P < .001) was the only significant predictive factor for failure of the no-touch technique. Among the 140 participants, LTP developed in two participants, and the estimated 1- and 2-year cumulative incidence of LTP was 0.7% and 1.6%, respectively. The estimated 1- and 2-year recurrence-free survival was 82.8% and 74.1%, respectively. Conclusion No-touch radiofrequency ablation was an effective and safe treatment method for small hepatocellular carcinomas (≤2.5 cm), with 1.6% of cumulative incidence of local tumor progression at 2 years. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Soulen and García-Mónaco in this issue.

Laparoscopic Liver Surgery Guided by Virtual Real-time CT-Guided Volume Navigation

BACKGROUND

Recently, virtual navigation system has been applied to hepatic surgery, enabling better visualization of intrahepatic vascular branches and location of tumor. Intraoperative ultrasonography (IOUS) is the most common form of image guidance during liver surgery. However, during laparoscopic hepatectomies (LH), IOUS has several limitations and its reliability has been poorly evaluated. The objective of this work is to evaluate VRCT (virtual real-time CT-guided volume navigation) during LH. This system aims to provide accurate anatomical orientation for surgeons enhancing the safety of LH.

METHODS

Twenty-seven hepatic neoplasms were resected laparoscopically at our institution under reference guidance of VRCT. During operation, electromagnetic tracking of the surgical instrument was used for navigating the direction of accurate liver transection.

RESULTS

Twenty-six (96.3%) of the 27 lesions (mean diameter 11 mm) were successfully performed under VRCT guidance. Average registration time was < 2 min. Average setup time was approximately 7 min per procedure. VRCT allows the surgeon to navigate liver transection with acceptable accuracy. The mean error was 12 mm. All surgical margins were negative and the mean histologic resection margin was 9 mm.

CONCLUSIONS

VRCT-guided LH is feasible and provides valuable real-time anatomical feedback during hepatic resections. Advancement of such systems to improve accuracy might greatly compensate for the limitation of laparoscopic IOUS.

Comparison of procedure-related complications between percutaneous cryoablation and radiofrequency ablation for treating periductal hepatocellular carcinoma

PURPOSE

This study aimed to evaluate the incidence and severity of biliary complications after treating periductal hepatocellular carcinomas (HCCs) using either cryoablation (CA) or radiofrequency ablation (RFA) and assess independent risk factors for biliary complications after treatment.

MATERIALS AND METHODS

Between July 2008 and August 2018, 949 patients with treatment-naïve HCCs underwent either RFA or CA in our institution. Of these, patients with multiple HCCs, tumors equal to or larger than 3 cm or smaller than 1 cm, and tumors with non-periductal locations were excluded. Finally, 31 patients and 25 patients were included in the RFA group and the CA group, respectively. The incidence and severity of biliary complications were compared between the RFA and CA groups. The risk factors for biliary complications were assessed using univariable and multivariable logistic regression analyses using the following variables: age, sex, tumor size, Child-Pugh score, tumor location (peripheral duct versus central duct), ablation method (RFA versus CA), the number of applicators, ablation time, and ablation volume.

RESULTS

The incidence and severity of biliary complications were significantly higher in the RFA group than in the CA group (p = 0.007 and p = 0.002, respectively). In univariable and multivariable analyses, the ablation method was an independent risk factor for biliary complications (p = 0.004 and 0.013, respectively).

CONCLUSIONS

The incidence and severity of biliary complications after treating HCCs abutting the bile duct are lower in CA than RFA, demonstrating that CA is safer than RFA for ablating small periductal HCCs.

Percutaneous radiofrequency ablation for hepatic metastasis of colorectal cancer: assessment of tumor visibility and the feasibility of the procedure with planning ultrasonography

Purpose

The aim of this study was to assess the incidence and causes of percutaneous radiofrequency ablation (RFA) infeasibility in cases of metastatic colorectal cancer and to evaluate factors affecting the invisibility of the tumor on planning ultrasonography (US).

Methods

This study screened 386 patients who underwent planning US using fusion imaging and/or contrast-enhanced US for percutaneous RFA for suspected metastatic colorectal cancer between January 2013 and December 2020, from whom 136 patients with a single hepatic metastasis from colorectal cancer measuring <3 cm were included. The factors related to the infeasibility of percutaneous RFA were investigated. Univariate and multivariate analyses were performed to assess the factors associated with tumor invisibility on planning US.

Results

Among the 136 patients, percutaneous RFA was considered infeasible in 24.3% (33/136) due to a high risk of the heat-sink effect caused by the abutment of a large vessel (n=12), an inconspicuous tumor on planning US (n=11), a high risk of collateral thermal damage to an adjacent organ (n=8), and the absence of a safe electrode path (n=2). In univariate and multivariate analyses, tumor size was a statistically significant factor affecting invisibility on planning US (P=0.003 and P=0.018, respectively).

Conclusion

Percutaneous RFA was infeasible in approximately one-fourth of patients with metastatic colorectal cancer. The reason for the infeasibility was mainly an unfavorable tumor location and invisibility on planning US. Small tumor size was the sole significant factor affecting the invisibility of hepatic metastases on planning US.

Challenges Facing Percutaneous Ablation in the Treatment of Hepatocellular Carcinoma: Extension of Ablation Criteria

As an emerging minimally invasive treatment method, percutaneous ablation is more and more widely used in the treatment of liver tumors. It has been recommended by guidelines for diagnosis and treatment of hepatocellular carcinoma (HCC) as a curative treatment alongside surgical resection and liver transplantation. In recent years, with the continuous advancement and innovation of percutaneous ablation technologies, their clinical efficacy and safety have been significantly improved, which has led to the expanded application of percutaneous ablation in the treatment of HCC—more and more patients who were previously considered unsuitable for ablation therapies are now being treated with percutaneous ablation. Obviously, percutaneous ablation can reduce the risk of treatment changes from curative strategies to palliative strategies. Based on clinical practice experience, this review enumerates the advantages and disadvantages of different ablative modalities and summarizes the existing combinations of ablation techniques, thus will help clinicians choose the most appropriate ablative modality for each patient and will provide scientific guidance for improving prognosis and making evidence-based treatment decisions. In addition, we point out the challenges and future prospects of the ablation therapies, thereby providing direction for future research.

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.

3D ultrasound guided navigation system with hybrid image fusion

A prototype of a navigation system to fuse two image modalities is presented. The standard inter-modality registration is replaced with a tracker-based image registration of calibrated imaging devices. Intra-procedure transrectal US (TRUS) images were merged with pre-procedure magnetic resonance (MR) images for prostate biopsy. The registration between MR and TRUS images was performed by an additional abdominal 3D-US (ab-3D-US), which enables replacing the inter-modal MR/TRUS registration by an intra-modal ab-3D-US/3D-TRUS registration. Calibration procedures were carried out using an optical tracking system (OTS) for the pre-procedure image fusion of the ab-3D-US with the MR. Inter-modal ab-3D-US/MR image fusion was evaluated using a multi-cone phantom for the target registration error (TRE) and a prostate phantom for the Dice score and the Hausdorff distance of lesions . Finally, the pre-procedure ab- 3D-US was registered with the TRUS images and the errors for the transformation from the MR to the TRUS were determined. The TRE of the ab-3D-US/MR image registration was 1.81 mm. The Dice-score and the Hausdorff distance for ab-3D-US and MR were found to be 0.67 and 3.19 mm. The Dice score and the Hausdorff distance for TRUS and MR were 0.67 and 3.18 mm. The hybrid navigation system showed sufficient accuracy for fusion guided biopsy procedures with prostate phantoms. The system might provide intra-procedure fusion for most US-guided biopsy and ablation interventions.

Role of Fusion Imaging in Image-Guided Thermal Ablations

Thermal ablation (TA) procedures are effective treatments for several kinds of cancers. In the recent years, several medical imaging advancements have improved the use of image-guided TA. Imaging technique plays a pivotal role in improving the ablation success, maximizing pre-procedure planning efficacy, intraprocedural targeting, post-procedure monitoring and assessing the achieved result. Fusion imaging (FI) techniques allow for information integration of different imaging modalities, improving all the ablation procedure steps. FI concedes exploitation of all imaging modalities’ strengths concurrently, eliminating or minimizing every single modality’s weaknesses. Our work aims to give an overview of FI, explain and analyze FI technical aspects and its clinical applications in ablation therapy and interventional oncology.

Transrectal Ultrasound MRI-Fusion Biopsy of Perirectal Mass

This case report describes the novel use of ultrasound-guided MRI-fusion biopsy to sample an extraluminal perirectal mass. This is a 64-year-old man with a history of pT3N2b mucinous adenocarcinoma of the right colon with metastatic disease to the mesocolic lymph nodes. Two years after initial resection he was found on restaging CT to have a mass measuring ∼4.0 × 4.8 cm superior to the seminal vesicles. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) showed a moderately FDG avid soft tissue mass interposed between the prostate and the rectum. Multiparametric MRI revealed a 6.2 × 4.6 × 2.8 cm heterogeneous lobulated T2 hyperintense mass with enhancement just superior to the seminal vesicles. This mass was unable to be viewed using sigmoidoscopy. Using UroNAV technology, we were able to biopsy the mass in the clinic setting. Biopsy was confirmed as recurrent mucinous adenocarcinoma.

Benefits of contrast-enhanced ultrasonography for interventional procedures

For evaluating unclear tumorous lesions, contrast-enhanced ultrasonography (CEUS) is an important imaging modality in addition to contrast-enhanced computed tomography and magnetic resonance imaging, and may provide valuable insights into the microvascularization of tumors in dynamic examinations. In interventional procedures, CEUS can make a valuable contribution in pre-, peri-, and post-interventional settings, reduce radiation exposure and, under certain circumstances, decrease the number of interventions needed for patients.

Integration of Real-Time Image Fusion in the Robotic-Assisted Treatment of Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma is one of the leading causes of cancer-related deaths worldwide. An image fusion system is developed for the robotic-assisted treatment of hepatocellular carcinoma, which is not only capable of imaging data interpretation and reconstruction, but also automatic tumor detection. The optimization and integration of the image fusion system within a novel robotic system has the potential to demonstrate the feasibility of the robotic-assisted targeted treatment of hepatocellular carcinoma by showing benefits such as precision, patients safety and procedure ergonomics.

Abstract

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide, with its mortality rate correlated with the tumor staging; i.e., early detection and treatment are important factors for the survival rate of patients. This paper presents the development of a novel visualization and detection system for HCC, which is a composing module of a robotic system for the targeted treatment of HCC. The system has two modules, one for the tumor visualization that uses image fusion (IF) between computerized tomography (CT) obtained preoperatively and real-time ultrasound (US), and the second module for HCC automatic detection from CT images. Convolutional neural networks (CNN) are used for the tumor segmentation which were trained using 152 contrast-enhanced CT images. Probabilistic maps are shown as well as 3D representation of HCC within the liver tissue. The development of the visualization and detection system represents a milestone in testing the feasibility of a novel robotic system in the targeted treatment of HCC. Further optimizations are planned for the tumor visualization and detection system with the aim of introducing more relevant functions and increase its accuracy.

Radiofrequency ablation using internally cooled wet electrodes in bipolar mode for the treatment of recurrent hepatocellular carcinoma after locoregional treatment: A randomized prospective comparative study

Objective

This study aimed to compare the efficacy between bipolar radiofrequency ablation (RFA), using twin internally cooled wet (TICW) electrodes, and switching monopolar RFA, using separable clustered (SC) electrodes, in the treatment of recurrent hepatocellular carcinoma (HCC) after locoregional treatment.

Materials and methods

In this single-center, two-arm, parallel-group, randomized controlled study, we performed a 1:1 random allocation on eligible patients with recurrent HCC after locoregional treatment, to receive TICW-RFA or SC-RFA. The primary endpoint was the minimum diameter of the ablation zone per unit ablation time. Secondary endpoints included other technical parameters, complication rate, technical success and technique efficacy, and clinical outcomes.

Results

Enrolled patients were randomly assigned to the TICW-RFA group (n = 40) or SC-RFA group (n = 37). The two groups did not show significant differences in the primary endpoint, the minimum diameter of the ablation zone per unit ablation time was 2.71 ± 0.98 mm/min and 2.61 ± 0.96 mm/min in the TICW-RFA and SC-RFA groups, respectively (p = 0.577). Total RF energy delivery (11.75 ± 9.04 kcal vs. 22.61 ± 12.98 kcal, p < 0.001) and energy delivery per unit time (0.81 ± 0.49 kcal/min vs. 1.45 ± 0.42 kcal/min, p < 0.001) of the TICW-RFA group were less than those of the SC-RFA group. No procedure-related death or major complications occurred. Technical success was achieved in all patients in both groups, and technique efficacy rates were 100% (46/46) in the TICW-RFA group and 95.0% (38/40) in the SC-RFA group (p = 0.213). The 1-year and 2-year cumulative LTP rates were 11.8% and 24.2%, respectively, in the TICW-RFA group, and 8.6% and 18.1%, respectively, in the SC-RFA group (p = 0.661).

Conclusion

In this single-center randomized controlled study from a Korean tertiary referral hospital, TICW-RFA demonstrated similar therapeutic efficacy and safety profile for recurrent HCC after locoregional treatment compared with SC-RFA.

Trial registration

ClinicalTrials.gov (NCT03806218)

Ultrasound 2020 - Diagnostics & Therapy: On the Way to Multimodal Ultrasound: Contrast-Enhanced Ultrasound (CEUS), Microvascular Doppler Techniques, Fusion Imaging, Sonoelastography, Interventional Sonography

BACKGROUND

 Ultrasound as a non-ionizing imaging procedure is one of the most important diagnostic procedures in everyday clinical practice. The technology is widely used. Due to constant technical innovations, sonographic procedures, such as contrast-enhanced ultrasound (CEUS), sonoelastography, new microvascular Doppler modalities and, as an example of interventional procedures, sonographically controlled microwave ablation (MWA), are becoming increasingly important in diagnostic imaging and interventional medicine alongside CT and MRI. However, this also requires greater expertise, specialization and qualification on the part of users.

METHOD

 This review article provides information about the range of technical innovations in ultrasound in recent years and describes the underlying technology, the clinical applications, and their diagnostic value. These are presented in the context of the current literature, explaining their advantages and disadvantages and their clinical value.

RESULTS AND CONCLUSION

 Contrast-enhanced ultrasound (CEUS), microvascular Doppler modalities, fusion imaging and elastography complement B-scan ultrasound and conventional Doppler procedures for various problems. Microwave ablation (MWA) has a firm place as an ablative procedure for local tumor therapy in different organ systems and can be performed under ultrasound guidance. Thanks to new developments, the possibilities of ultrasound are now greater than ever. Knowledge of the technology, indications, and possible applications of newer procedures is essential for adequate patient care.

KEY POINTS

  · Contrast-enhanced ultrasound (CEUS) allows an increase in sensitivity and specificity in the assessment of parenchymal lesions.. · CEUS allows the microperfusion to be visualized and quantified. For larger vessels, CEUS is an important instrument in diagnosing endoleak after stenting.. · Microvascular Doppler techniques with clutter suppression algorithms allow a more accurate representation of the smallest vessels than regular color or power Doppler.. · Elastography of the liver in diffuse hepatopathies is a noninvasive diagnostic tool to exclude higher grade fibrosis/cirrhosis.. · Microwave ablation (MWA) also offers sonographically controlled ablation of tumors..

CITATION FORMAT

· Kloth C, Kratzer W, Schmidberger J et al. Ultrasound 2020 - Diagnostics & Therapy: On the Way to Multimodal Ultrasound: Contrast-Enhanced Ultrasound (CEUS), Microvascular Doppler Techniques, Fusion Imaging, Sonoelastography, Interventional Sonography . Fortschr Röntgenstr 2021; 193: 23 - 32.

Intra-procedural real-time ultrasound fusion imaging improves the therapeutic effect and safety of liver tumor ablation in difficult cases

In certain difficult cases involving tumors unclear in B-mode ultrasound or tumors in a high-risk location, image-guided liver tumor thermal ablation was previously contraindicated. The aim of this retrospective study was to investigate the value of intra-procedural ultrasound fusion imaging in improving the therapeutic effect and safety of liver tumor ablation in difficult cases. A total of 502 patients (441 males and 61 females, aged 52 ± 11 years) with 805 liver tumors (16 ± 6 mm; range, 4-29 mm) who underwent thermal ablation with intra-procedural fusion imaging from October 2010 to June 2018 in our hospital were enrolled. Fusion imaging was employed for targeting, puncture guidance and immediate evaluation of the therapeutic response. Contrast-enhanced computed tomography (CT)/magnetic resonance imaging (MRI) was performed one month after ablation and every 3~6 months in the follow-up period. 511 and 294 liver tumors were in classified in the difficult case group and the non-difficult case group, respectively. The technical efficacy rate was 99.4% (800/805), and no difference was found between the two groups (P=0.658). No significant difference in the local tumor progression rate was found between the difficult case group (1 year: 3.2%; 3 years: 7.6%; 5 years: 7.6%) and non-difficult case group (1 year: 2.1%; 3 years: 5.5%; 5 years: 11.6%) (P=0.874). The major complication rate was 1.8% (11/608). Injury to adjacent organs occurred in only 1 patient who sustained a bile duct injury. We conclude that intra-procedural fusion imaging can improve the therapeutic efficacy and safety of thermal ablation in difficult cases and may expand the indications for thermal ablation.

Manual versus automated image fusion of real-time ultrasonography and MR/CT images for radiofrequency ablation of hepatic tumors: results of a randomized prospective trial (NCT02705118)

PURPOSE

This study compared the technical parameters and clinical outcomes of manual and automatic image fusion techniques of ultrasonography and magnetic resonance imaging/computed tomography for radiofrequency ablation (RFA) of hepatic tumors.

METHODS

Seventy consecutive patients (male:female=47:23, 67.1±10.9 years old) who underwent RFA for hepatic tumors were prospectively enrolled and randomly assigned to the manual or automatic registration group. Two operators performed RFA with one of two imaging fusion techniques. Technical parameters (the registration error, time required for image registration, number of point registrations) and clinical outcomes (technical success, technical effectiveness, local tumor progression [LTP]-free survival, and progression-free survival [PFS]) were compared.

RESULTS

The automatic group contained 35 patients with hepatocellular carcinoma, while the manual group included 34 hepatocellular carcinoma patients and a patient with colon cancer liver metastasis. The registration error, time required for registration, and number of point registrations were 5.7±4.3 mm, 147.8±78.2 seconds, and 3.26±1.20 in the automatic group, and 6.3±5.0 mm, 150.3±89.7 seconds, and 3.20±1.13 in the manual group, respectively. The technical success and effectiveness rates were both 97.1% in the automatic group and both 100.0% in the manual group. The above differences were not significant. The LTP-free survival and PFS (28.3 and 21.2 months in the automatic group, and 29.0 and 24.9 months in the manual group, respectively) showed no significant between-group differences during a median 20.1-month follow-up period.

CONCLUSION

The technical parameters and clinical outcomes of automatic image fusion were not significantly different from those of manual image fusion for RFA of hepatic tumors.

A closer look to the new frontier of artificial intelligence in the percutaneous treatment of primary lesions of the liver

The purpose of thermal ablation is induction of tumor death by means of localized hyperthermia resulting in irreversible cellular damage. Ablative therapies are well-recognized treatment modalities for HCC lesions and are considered standard of care for HCC nodules < 3 cm in diameter in patients not suitable for surgery. Effective lesion treatment rely on complete target volume ablation. Technical limitations are represented by large (> 3 cm) or multicentric nodules as well as complex nodule location and poor lesion conspicuity. Artificial Intelligence (AI) is a general term referred to computational algorithms that can analyze data and perform complex tasks otherwise prerogative of Human Intelligence. AI has a variety of application in percutaneous ablation procedures such as Navigational software, Fusion Imaging, and robot-assisted ablation tools. Those instruments represent relative innovations in the field of Interventional Oncology and promising strategies to overcome actual limitations of ablative therapy in order to increase feasibility and technical results. This work aims to review the principal application of Artificial Intelligence in the percutaneous ablation of primary lesions of the liver with special focus on how AI can impact in the treatment of HCC especially on potential advantages on the drawbacks of the conventional technique.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Current role of ultrasound in the diagnosis of hepatocellular carcinoma

Ultrasonography (US) is a major, sustainable hepatocellular carcinoma (HCC) surveillance method as it provides inexpensive, real-time, and noninvasive detection. Since US findings are based on pathological features, knowledge of pathological features is essential for delivering a correct US diagnosis. Recent advances in US equipment have made it possible to provide more information, such as malignancy potential and accurate localization diagnosis of HCC. Evaluation of malignancy potential is important to determine the treatment strategy, especially for small HCC. Diagnosis of blood flow dynamics using color Doppler and contrast-enhanced US is one of the most definitive approaches for evaluating HCC malignancy potential. Recently, a new Doppler microvascular imaging technique, superb microvascular imaging, which can detect Doppler signals generated by low-velocity blood flow, was developed. A fusion imaging system, another innovative US technology, has already become an indispensable technology over the last few years not only for US-guided radiofrequency ablation but also for the detection of small, invisible HCC. This article reviews the evidence on the use of ultrasound and contrast-enhanced ultrasound with Sonazoid for the practical management of HCC.

Application of Image Fusion in Diagnosis and Treatment of Liver Cancer

With the accelerated development of medical imaging equipment and techniques, image fusion technology has been effectively applied for diagnosis, biopsy and radiofrequency ablation, especially for liver tumor. Tumor treatment relying on a single medical imaging modality might face challenges, due to the deep positioning of the lesions, operation history and the specific background conditions of the liver disease. Image fusion technology has been employed to address these challenges. Using the image fusion technology, one could obtain real-time anatomical imaging superimposed by functional images showing the same plane to facilitate the diagnosis and treatments of liver tumors. This paper presents a review of the key principles of image fusion technology, its application in tumor treatments, particularly in liver tumors, and concludes with a discussion of the limitations and prospects of the image fusion technology.