Clinical impact of cone beam computed tomography on iterative treatment planning during ultrasound-guided percutaneous ablation of liver malignancies

Clinical Impact of a Protocol Involving Cone-Beam CT (CBCT), Fusion Imaging and Ablation Volume Prediction in Percutaneous Image-Guided Microwave Ablation in Patients with Hepatocellular Carcinoma Unsuitable for Standard Ultrasound (US) Guidance

PURPOSE

to evaluate the clinical impact of a protocol for the image-guided percutaneous microwave ablation (MWA) of hepatocellular carcinoma (HCC) that includes cone-beam computed tomography (CBCT), fusion imaging and ablation volume prediction in patients with hepatocellular carcinoma unsuitable for standard ultrasound (US) guidance.

MATERIALS AND METHODS

this study included all patients with HCC treated with MWA between January 2021 and June 2022 in a tertiary institution. Patients were divided into two groups: Group A, treated following the protocol, and Group B, treated with standard ultrasound (US) guidance. Follow-up images were reviewed to assess residual disease (RD), local tumor progression (LTP) and intrahepatic distant recurrence (IDR). Ablation response at 1 month was also evaluated according to mRECIST. Baseline variables and outcomes were compared between the groups. For 1-month RD, propensity score weighting (PSW) was performed.

RESULTS

80 consecutive patients with 101 HCCs treated with MWA were divided into two groups. Group A had 41 HCCs in 37 patients, and Group B had 60 HCCs in 43 patients. Among all baseline variables, the groups differed regarding their age (mean of 72 years in Group A and 64 years in Group B, respectively), new vs. residual tumor rates (48% Group A vs. 25% Group B, p < 0.05) and number of subcapsular tumors (56.7% Group B vs. 31.7% Group A, p < 0.05) and perivascular tumors (51.7% Group B vs. 17.1% Group A, p < 0.05). The protocol led to repositioning the antenna in 49% of cases. There was a significant difference in 1-month local response between the groups measured as the RD rate and mRECIST outcomes. LTP rates at 3 and 6 months, and IDR rates at 1, 3 and 6 months, showed no significant differences. Among all variables, logistic regression after PSW demonstrated a protective effect of the protocol against 1-month RD.

CONCLUSIONS

The use of CBCT, fusion imaging and ablation volume prediction during percutaneous MWA of HCCs provided a better 1-month tumor local control. Further studies with a larger population and longer follow-up are needed.

Percutaneous Microwave Ablation of Hepatocellular Carcinoma with "Double Fusion" Technique: Technical Note and Single-Center Preliminary Experience

Percutaneous image-guided thermal ablation is included in most society guidelines for treatment of hepatocellular carcinoma (HCC). The results of this treatment in terms of efficacy depend on the ability to precisely place the device into the target tumor. Ultrasound (US) is a commonly used imaging guidance modality for its real-time feedback. However, an accurate device deployment remains challenging in some clinical scenarios, including cases of tumors that are undetectable or not clearly visible by US. To overcome this problem, fusion imaging techniques have been developed, which combine images from different modalities. The most widely known technique combines pre-procedural contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) with real-time US scans. Cone beam CT (CBCT) is a technology that can provide intra-procedural cross-sectional images, which can be registered to images from other modalities, including preprocedural CT/MR scans. The aim of our study is to report the preliminary experience on percutaneous microwave ablation (MWA) of patients with HCC that were treated using the "double fusion" technique, which combines the use of US fusion imaging and CBCT fusion imaging. We describe the technical details, feasibility, safety and short-term efficacy of this technique in a small series of eight patients with 11 HCCs.

Clinical Results, Risk Factors, and Future Directions of Ultrasound-Guided Percutaneous Microwave Ablation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, with a relatively poor prognosis, especially for advanced HCC. With the availability of a variety of treatment options, the treatment strategies for HCC have become more and more diversified. Microwave ablation (MWA) has gradually been considered as a viable alternative to surgical resection (SR) owing to its comparable long-term survival, reduced complications, and greater preservation of hepatic parenchyma. However, clinical outcomes, tumor progression, and recurrence of HCC after MWA remain major concerns. Here, after reviewing the current therapeutic options for HCC, we focus on MWA, describing the advantages and challenges of MWA and the clinical results after treatment. We then focused on prognostic factors that influence post-ablation clinical outcomes and briefly presented the strategy of MWA for future clinical treatment.

Virtual Treatment Zone From Cone Beam CT Commonly Alters Treatment Plan and Identifies Tumor at Risk for Under-Treatment in US or US Fusion-Guided Microwave Ablation of Liver Tumors

Tumor ablation is included in several major cancer therapy guidelines. One technical challenge of percutaneous ablation is targeting and verification of complete treatment, which is prone to operator variabilities and human imperfections and are directly related to successful outcomes, risk for residual unablated tumor and local progression. The use of "Prediction Ablation Volume Software" may help the operating Interventional Radiologist to better plan, deliver, and verify before the ablation, via virtual treatment zones fused to target tumor. Fused and superimposed images provide 3-dimensional information from different timepoints, just when that information is most useful. The aim of this study is to evaluate the technical success and efficacy of an ablation treatment flowchart provided by a cone beam computed tomography (CBCT) "Prediction Ablation Volume Software." This is a single-center retrospective study. From April 2021 to January 2022, 29 nonconsecutive evaluable patients with 32 lesions underwent liver ablation with Prediction Ablation Volume Software. Each patient was discussed in a multidisciplinary tumor board and underwent an enhanced computed tomography or magnetic resonance imaging approximately 1 month before the procedure, as well as ∼1 month after. Technical success was defined as treatment of the tumor according to the protocol, covered completely by the Prediction Ablation Volume. Technical efficacy was defined as assessment of complete ablation of the target tumor at imaging follow up (∼1 month). Technical success, technical efficacy, and procedural factors were studied. Technical success was achieved in 30 of 32 liver lesions (94%), measuring 20 mm mean maximum diameter. The antenna was repositioned in 16 of 30 (53%) evaluable target lesions. Residual tumor was detected at 1 month imaging follow up in only 4 of 30 (13%) of the treated lesion. Technical efficacy was of 87% in this retrospective description of our process. The implementation of a CBCT Prediction Ablation Volume Software and flowchart for the treatment of liver malignancies altered the procedure, and demonstrated high technical success and efficacy. Such tools are potentially useful for procedural prediction and verification of ablation.

Precision Imaging Guidance in the Era of Precision Oncology: An Update of Imaging Tools for Interventional Procedures

Interventional oncology (IO) procedures have become extremely popular in interventional radiology (IR) and play an essential role in the diagnosis, treatment, and supportive care of oncologic patients through new and safe procedures. IR procedures can be divided into two main groups: vascular and non-vascular. Vascular approaches are mainly based on embolization and concomitant injection of chemotherapeutics directly into the tumor-feeding vessels. Percutaneous approaches are a type of non-vascular procedures and include percutaneous image-guided biopsies and different ablation techniques with radiofrequency, microwaves, cryoablation, and focused ultrasound. The use of these techniques requires precise imaging pretreatment planning and guidance that can be provided through different imaging techniques: ultrasound, computed tomography, cone-beam computed tomography, and magnetic resonance. These imaging modalities can be used alone or in combination, thanks to fusion imaging, to further improve the confidence of the operators and the efficacy and safety of the procedures. This article aims is to provide an overview of the available IO procedures based on clinical imaging guidance to develop a targeted and optimal approach to cancer patients.

Interventional Radiology ex-machina: impact of Artificial Intelligence on practice

Artificial intelligence (AI) is a branch of Informatics that uses algorithms to tirelessly process data, understand its meaning and provide the desired outcome, continuously redefining its logic. AI was mainly introduced via artificial neural networks, developed in the early 1950s, and with its evolution into "computational learning models." Machine Learning analyzes and extracts features in larger data after exposure to examples; Deep Learning uses neural networks in order to extract meaningful patterns from imaging data, even deciphering that which would otherwise be beyond human perception. Thus, AI has the potential to revolutionize the healthcare systems and clinical practice of doctors all over the world. This is especially true for radiologists, who are integral to diagnostic medicine, helping to customize treatments and triage resources with maximum effectiveness. Related in spirit to Artificial intelligence are Augmented Reality, mixed reality, or Virtual Reality, which are able to enhance accuracy of minimally invasive treatments in image guided therapies by Interventional Radiologists. The potential applications of AI in IR go beyond computer vision and diagnosis, to include screening and modeling of patient selection, predictive tools for treatment planning and navigation, and training tools. Although no new technology is widely embraced, AI may provide opportunities to enhance radiology service and improve patient care, if studied, validated, and applied appropriately.

Feasibility of 3D US/CEUS-US/CEUS fusion imaging-based ablation planning in liver tumors: a retrospective study

PURPOSE

To assess the feasibility of ablation planning based on fusion imaging of three-dimensional ultrasound/contrast-enhanced ultrasound (3D US/CEUS) with real-time US/CEUS for liver tumor thermal ablation.

MATERIALS AND METHODS

Between January 2017 and December 2018, 85 hepatic tumors from 82 patients who underwent percutaneous ablation were included. First, intraprocedural 3D US/CEUS imaging was performed for ablation planning. Then, fusion imaging of 3D US/CEUS with real-time US/CEUS was used to guide the implementation of the plan, immediately evaluate the technical success and indicate the need for supplemental ablation. In addition, contrast-enhanced CT/MR imaging was performed 1 month after the procedure to evaluate the presence of residual tumors, and follow-up scans were repeated every 3 months.

RESULTS

The average liver tumor diameter was 28 ± 9 mm (range, 10-55 mm). 3D US/CEUS-based planning was successfully conducted in all 85 tumors with a 100% technical success rate of planning. The immediate evaluation by 3D CEUS/US-CEUS fusion imaging showed a 100% technical success rate of ablation. The 1-month CT/MR scans found a residual tumor in one intrahepatic cholangiocarcinoma patient; the technique efficacy rate was 98.8%. The median follow-up period was 21.5 months (IQR: 4-36 months). During the follow-up period, the local tumor progression rate was 5.9% (5/84), and no major procedure-related complications occurred.

CONCLUSIONS

Ablation planning based on 3D US/CEUS-US/CEUS fusion imaging is feasible for liver tumors.

A thermochromic tissue-mimicking phantom model for verification of ablation plans in thermal ablation

Background

Our study aims to develop a novel tissue-mimicking thermochromic with tumor model for visualization of thermal ablation and verification of ablation plans.

Methods

Polyacrylamide gel was mixed with thermochromic ink to produce a phantom model. A phantom model embedded in a tumor model was constructed and used to evaluate the ablation procedure. The phantom models were randomly divided into complete ablation group and incomplete ablation group. The ablation planning of the tumor was on the 3D US and performed on a phantom model. We guide the ablation procedures according to the ablation planning. The results measured in a gross specimen of the phantom model were compared with the expected results in ablation planning.

Results

The color of the model changes from cream white to magenta after heating. The mono-site ablation area is a spheroid after thermal ablation with a size of 3.0×1.8 cm at 60 W, 5 minutes, 3.5×2.5 cm at 60 W, 10 minutes, and 4.0×3.5 cm at 60 W, 15 minutes, respectively. According to the ablation planning, a total of 4 ablation points were needed to retrieve the complete ablation of a 3.0 cm tumor. The complete ablation and incomplete ablation were proved by a gross specimen of the phantom model as we expected.

Conclusions

A novel thermochromic tissue-mimicking phantom model with a spherical tumor model has been designed and developed. The ablation area can be visualized on this phantom model by the permanent color change. This phantom model can assess the ablation planning system's accuracy and train operators for ultrasound-guided thermal ablation.

Prostatic artery embolization in patients with benign prostatic hyperplasia: perfusion cone-beam CT to evaluate planning and treatment response

This proof of concept is to evaluate the utility of perfusion cone-beam computed tomography (CT) in patients undergoing prostatic artery (PA) embolization (PAE) for benign prostatic hyperplasia (BPH) with moderate or severe-grade lower urinary tract symptoms (LUTS). PAE is a novel minimally invasive therapy and is both safe and effective procedure with low risks and high technical successes, making this procedure as the best alternative to surgery. A lot of technical changes would compromise clinical outcomes after procedure, including a variable prostate vascular anatomy, thin PA, and extensive atherosclerotic disease. The purpose of our study is to exploit the advantages of Perfusion Cone Beam Computed Tomography (CBCT) that could impact treatment and help interventional radiologists for treatment planning, diagnosis and for assessing the technical feasibility during PAE, mitigating the risk of nontarget embolization and suggesting clinical outcomes. Qualitative and quantitative clinical pre- and post-treatment values will be compared, to reach the best possible results.

Hepatic tumors: pitfall in diagnostic imaging

On computed tomography (CT) and magnetic resonance imaging (MRI), hepatocellular tumors are characterized based on typical imaging findings. However, hepatocellular adenoma, focal nodular hyperplasia, and hepatocellular carcinoma can show uncommon appearances at CT and MRI, which may lead to diagnostic challenges. When assessing focal hepatic lesions, radiologists need to be aware of these atypical imaging findings to avoid misdiagnoses that can alter the management plan. The purpose of this review is to illustrate a variety of pitfalls and atypical features of hepatocellular tumors that can lead to misinterpretations providing specific clues to the correct diagnoses. (www.actabiomedica.it)

Extranodal Lymphomas: a pictorial review for CT and MRI classification

Extranodal lymphomas represent an extranodal location of both non-Hodgkin and Hodgkin lymphomas. This study aims to evaluate the role of CT and MRI in the assessment of relationships of extranodal lymphomas with surrounding tissues and in the characterization of the lesion. We selected and reviewed ten recent studies among the most recent ones present in literature exclusively about CT and MRI imaging of extranodal lymphomas. Contrast-enhanced computed tomography (CT) is usually the first-line imaging modality in the evaluation of extranodal lymphomas, according to Lugano classification. However, MRI has a crucial role thanks to the superior soft-tissue contrast resolution, particularly in the anatomical region as head and neck. (www.actabiomedica.it)

Basic embolization techniques: tips and tricks

Good knowledge of the various approaches of embolization of peripheral bleedings and different embolic materials available is of paramount importance for successful and safe embolization. We review and illustrate the main endovascular and percutaneous techniques used for embolization, along with the characteristics of the different embolic materials, and the potential complications.

Diagnostic and interventional radiology: an update

NOT PRESENT.

Imaging guided percutaneous renal biopsy: do it or not?

Since its first reported application, renal biopsy became an important part of the diagnostic algorithm, considered advantages and risks, to better manage therapeutic options. The biopsy can be performed with different techniques (open, laparoscopic, transjugular, transurethral and percutaneous). Currently, the percutaneous approach is the modality of choice. Percutaneous biopsy can be performed under CT or US guidance, but critical benefits and disadvantages have to be considered. Core needle biopsy is usually preferred to fine-needle aspiration because of the sample quality, usually obtaining multiple cores, especially in heterogeneous tumors. Principal complications are hematuria (1-10%), perinephric hematoma (10-90%), pneumothorax (0,6%), clinically significant pain (1,2%).

Multiphysics modeling toward enhanced guidance in hepatic microwave ablation: a preliminary framework

We compare a surface-driven, model-based deformation correction method to a clinically relevant rigid registration approach within the application of image-guided microwave ablation for the purpose of demonstrating improved localization and antenna placement in a deformable hepatic phantom. Furthermore, we present preliminary computational modeling of microwave ablation integrated within the navigational environment to lay the groundwork for a more comprehensive procedural planning and guidance framework. To achieve this, we employ a simple, retrospective model of microwave ablation after registration, which allows a preliminary evaluation of the combined therapeutic and navigational framework. When driving registrations with full organ surface data (i.e., as could be available in a percutaneous procedure suite), the deformation correction method improved average ablation antenna registration error by 58.9% compared to rigid registration (i.e., 2.5 ± 1.1    mm , 5.6 ± 2.3    mm of average target error for corrected and rigid registration, respectively) and on average improved volumetric overlap between the modeled and ground-truth ablation zones from 67.0 ± 11.8 % to 85.6 ± 5.0 % for rigid and corrected, respectively. Furthermore, when using sparse-surface data (i.e., as is available in an open surgical procedure), the deformation correction improved registration error by 38.3% and volumetric overlap from 64.8 ± 12.4 % to 77.1 ± 8.0 % for rigid and corrected, respectively. We demonstrate, in an initial phantom experiment, enhanced navigation in image-guided hepatic ablation procedures and identify a clear multiphysics pathway toward a more comprehensive thermal dose planning and deformation-corrected guidance framework.

Computed tomography densitometric study of anti-angiogenic effect of regorafenib in colorectal cancer liver metastasis

Aim: Regorafenib induces radiological changes in liver metastasis among patients with metastatic colorectal cancer (mCRC). The standard criteria used to evaluate solid tumor response (Response Evaluation Criteria in Solid Tumors) may be limited in assessing response to biologic agents with anti-angiogenic action. Patients & methods: A total of 67 hepatic lesions in 32 selected patients were analyzed to evaluate tumor attenuation as measured by Hounsfield unit (HU) and size changes. Results: Following two cycles of regorafenib, tumor HU values decreased in the in 73.1% (49/67) of lesions (average HU changes -25.6%) while tumor size increased in 64.2% (43/67) of them (average size changes +25.4%). Conclusion: The computed tomography density changes evaluation may be an additional tool, in combination with tumor sizing, to evaluate tumor response in patients treated with regorafenib.

A Novel CT to Cone-Beam CT Registration Method Enables Immediate Real-Time Intraprocedural Three-Dimensional Assessment of Ablative Treatments of Liver Malignancies

Aim

To evaluate a novel contrast-enhanced cone-beam computed tomography (CE-CBCT) registration method for accurate immediate assessment of ablation outcomes.

Materials and Methods

Contrast-enhanced computed tomography (CECT) was registered with CE-CBCT by applying semiautomatic landmark registration followed by automatic affine and non-rigid registration to correct for respiratory phase differences and liver deformation. This scheme was retrospectively applied to 30 patients who underwent 38 percutaneous microwave liver ablations. Three datasets were obtained for each case: (1) conventional CECT scans 24 h before ablation, (2) intraprocedural CE-CBCT scans, and (3) CECT scans 24 h post-ablation. Using a five-point scale, two experienced radiologists qualitatively assessed registration quality, equivalence of CE-CBCT assessment of ablation outcome to 24 h post-ablation CECT, and perceived increase of confidence using the fusion method to CBCT alone. Additionally, residual post-ablation tumor volumes were measured at both CE-CBCT and 24 h CECT and compared to the pre-CECT.

Results

Registration quality was high for both radiologists (R1: 4.3 ± 0.6, R2: 4.4 ± 0.5; p = 0.87). Comparisons between the registration of pre-ablation CECT with CE-CBCT versus post-ablation CECT regarding the position of the ablated area to the treated target (R1: 4.4 ± 0.6, R2: 4.6 ± 0.4) and treatment outcome (R1: 4.5 ± 0.5, R2: 4.6 ± 0.4) were equivalent (p > 0.35). Increased confidence was noted when using fusion (R1: 4.6 ± 0.4, R2: 4.6 ± 0.4; p = 0.84). Moreover, in 6 ablations (15.8%) the intraprocedural registered CBCT showed residual tumor precisely where identified on the 24 h post-ablation CECT.

Conclusions

Combined CE-CBCT holds the potential to change the current workflow of mini-invasive cancer local treatments. Given earlier visual identification of residual tumor post-ablation, this includes potentially eliminating the need for some additional treatments.