Xavier Buy

An augmented reality system for liver thermal ablation: Design and evaluation on clinical cases

We present in this paper an augmented reality guidance system for liver thermal ablation in interventional radiology. To show the relevance of our methodology, the system is incrementally evaluated on an abdominal phantom and then on patients in the operating room. The system registers in a common coordinate system a preoperative image of the patient and the position of the needle that the practitioner manipulates. The breathing motion uncertainty is taken into account with a respiratory gating technique: the preoperative image and the guidance step are synchronized on expiratory phases. In order to fulfil the real-time constraints, we have developed and validated algorithms that automatically process and extract feature points. Since the guidance interface is also a major component of the system effectiveness, we validate the overall targeting accuracy on an abdominal phantom. This experiment showed that a practitioner can reach a predefined target with an accuracy of 2mm with an insertion time below one minute. Finally, we propose a passive evaluation protocol of the overall system in the operating room during five interventions on patients. These experiments show that the system can provide a guidance information during expiratory phases with an error below 5mm.

Temperature monitoring during microwave ablation in ex vivo porcine livers

OBJECTIVE The aim of the present study was to assess the temperature map and its reproducibility while applying two different MWA systems (915 MHz vs 2.45 GHz) in ex vivo porcine livers. MATERIALS AND METHODS Fifteen fresh pig livers were treated using the two antennae at three different settings: treatment time of 10 min and power of 45 W for both systems; 4 min and 100 W for the 2.45 GHz system. Trends of temperature were recorded during all procedures by means of fiber optic-based probes located at five fixed distances from the antenna, ranging between 10 mm and 30 mm. Each trial was repeated twice to assess the reproducibility of temperature distribution. RESULTS Temperature as function of distance from the antenna can be modeled by a decreasing exponential trend. At the same settings, temperature obtained with the 2.45 GHz system was higher than that obtained with the 915 MHz thus resulting into a wider area of ablation (diameter 17 mm vs 15 mm). Both systems showed good reproducibility in terms of temperature distribution (root mean squared difference for both systems ranged between 2.8 °C and 3.4 °C). CONCLUSIONS When both MWA systems are applied, a decreasing exponential model can predict the temperature map. The 2.45 GHz antenna causes higher temperatures as compared to the 915 MHz thus, resulting into larger areas of ablation. Both systems showed good reproducibility although better results were achieved with the 2.45 GHz antenna.

Percutaneous thermal ablation of primary lung cancer

Percutaneous ablation of small-size non-small-cell lung cancer (NSCLC) has demonstrated feasibility and safety in nonsurgical candidates. Radiofrequency ablation (RFA), the most commonly used technique, has an 80-90% reported rate of complete ablation, with the best results obtained in tumors less than 2-3cm in diameter. The highest one-, three-, and five-year overall survival rates reported in NSCLC following RFA are 97.7%, 72.9%, and 55.7% respectively. Tumor size, tumor stage, and underlying comorbidities are the main predictors of survival. Other ablation techniques such as microwave or cryoablation may help overcome the limitations of RFA in the future, particularly for large tumors or those close to large vessels. Stereotactic ablative radiotherapy (SABR) has its own complications and carries the risk of fiducial placement requiring multiple lung punctures. SABR has also demonstrated significant efficacy in treating small-size lung tumors and should be compared to percutaneous ablation.

First-in-Human Study Testing a New Radioenhancer Using Nanoparticles (NBTXR3) Activated by Radiation Therapy in Patients with Locally Advanced Soft Tissue Sarcomas

Purpose: This phase I study aimed to determine the recommended dose (RD), safety profile, and feasibility of a procedure combining intratumoral injection of hafnium oxide nanoparticles (NBTXR3; a radioenhancer) and external beam radiotherapy (EBRT) for preoperative treatment of adults with locally advanced soft tissue sarcoma (STS). Experimental Design: Patients had a preoperative indication of EBRT for STS of the extremity or trunk. Baseline tumor volume (TV) was calculated by MRI. NBTXR3 was injected percutaneously into tumors at 53.3 g/L. Dose escalation was based on four levels equivalent to 2.5%, 5%, 10%, and 20% of baseline TV. NBTXR3 was visualized in the tumor 24 hours postinjection, and EBRT was initiated (50 Gy over 5 weeks). Surgery was performed 6 to 8 weeks after EBRT completion. Results: Twenty-two patients completed NBTXR3 injection, EBRT, and surgery and were followed for a median 22 months (range, 6–40). At NBTXR3 20% of TV, two dose-limiting toxicities occurred: injection-site pain and postoperative scar necrosis. The RD was defined as 10%. No leakage of NBTXR3 into surrounding tissues occurred; intratumor NBTXR3 levels were maintained during radiotherapy. At the RD, median tumor shrinkage was 40% (range 71% shrinkage, 22% increase); median percentage of residual viable tumor cells was 26% (range, 10%–90%). Patients receiving 20% of TV demonstrated pathologic complete responses. Seven grade 3 adverse events occurred, which were reversible. Conclusions: A single intratumoral injection of NBTXR3 at 10% of TV with preoperative EBRT was technically feasible with manageable toxicity; clinical activity was observed. Clin Cancer Res; 23(4); 908–17. ©2016 AACR.

Percutaneous Image-Guided Cryoablation of Breast Cancer: A Systematic Review.

A systematic review of the clinical safety and efficacy of percutaneous breast cancer cryoablation was performed. Of 202 papers screened, seven matched the inclusion criteria. Cryoablation was mainly performed under ultrasound guidance, and on average two cryoprobes were used. Complete local tumor control was noted in 73% of patients (mean follow-up, 8 mo). No major complications were noted. The cosmetic outcome was satisfactory. Breast cancer cryoablation is safe, although local tumor control is suboptimal. The best results are achieved with small (<15 mm) ductal tumors treated by application of multiple cryoprobes.

Rare complications after lung percutaneous radiofrequency ablation: Incidence, risk factors, prevention and management

Among image-guided thermo-ablative techniques, percutaneous radiofrequency ablation (PRFA) is the most widely used technique for the treatment of primary and secondary lung malignancies. Tolerance of PRFA in the lung is excellent. However, relatively little is known about potential rare complications. This article presents both the clinical and imaging features of lung PRFA complications as well as their prevention and management. Complications may be classified in four groups: pleuropulmonary (e.g., bronchopleural or bronchial fistula, delayed abscess or aspergilloma inside post-PRFA cavitations, pulmonary artery pseudo aneurysm, gas embolism and interstitial pneumonia); thoracic wall and vertebral (e.g., rib or vertebral fractures and intercostal artery injury); mediastinal and apical (e.g., neural damage); or diaphragmatic. Most complications can be managed with conservative treatment, percutaneous or endoscopic drainage, or surgical repair.

Percutaneous thermal ablation of lung tumors – Radiofrequency, microwave and cryotherapy: Where are we going?

Main indications of percutaneous pulmonary thermal ablation are early stage non-small cell lung carcinoma (NSCLC) for patients who are not amenable to surgery and slow-evolving localized metastatic disease, either spontaneous or following a general treatment. Radiofrequency ablation (RFA) is the most evaluated technique. This technique offers a local control rate ranging between 80 and 90% for tumors <3cm in diameter. Other more recently used ablation techniques such as microwaves and cryotherapy could overcome some limitations of RFA. One common characteristic of these techniques is an excellent tolerance with very few complications. This article reviews the differences between these techniques when applied to lung tumors, indications, results and complications. Future potential associations with immunotherapy will be discussed.

PET/Computed Tomography and Thermoablation (Radiofrequency, Microwave, Cryotherapy, Laser Interstitial Thermal Therapy).

Thermal ablation (radiofrequency, microwave, cryosurgery, laser interstitial thermal therapy) is being used more frequently as a local treatment of secondary but also primary cancers and benign lesions. It has a low morbidity and is repeatable. The problem is that computed tomographic scan has limits, and RECIST criteria are not applicable. The objective of this article is to summarize the usefulness and pitfalls of PET/computed tomography in detecting a relapse after thermal ablation as soon as possible.

Intravertebral pseudomeningocele: an unusual complication after disc surgery.

BACKGROUND CONTEXT Pseudomeningoceles are most commonly the result of dural tear during spine surgery. They may sometimes slowly enlarge but they generally develop inside the spinal canal, toward the foramina or toward the surgical incision. PURPOSE To describe a late and exceptional complication of a surgical discectomy. STUDY DESIGN A case report. METHODS We report a unique case of a large asymptomatic pseudomeningocele strictly developed in the L5 vertebra, discovered incidentally in a 38-year-old woman. Computed tomography and magnetic resonance imaging showed a large cystic lesion involving the vertebral body and the left pedicle of L5 without contrast enhancement. There was neither extension of the cyst toward the vertebral lamina nor toward the spinal canal. Consent to publish the data was obtained from our patient. RESULTS Diagnosis was performed during transpedicular image-guided puncture, when opacification of the cyst revealed dural communication. Biochemical analysis and cytology confirmed the presence of cerebrospinal fluid and absence of tumoral cells. CONCLUSIONS Dural tear was considered as a neglected complication after surgical discectomy at the same level performed 18 years ago. Differential diagnoses of cystic spinal lesions are discussed.

High-grade soft-tissue sarcoma: optimizing injection improves MRI evaluation of tumor response

ObjectivesTo determine the acquisition delay after gadolinium-chelate injection that optimizes the prediction of the histological response during anthracycline-based neoadjuvant chemotherapy (NAC) for locally advanced high-grade soft-tissue sarcomas (STS).MethodsThirty patients (mean age 62 years) were included in this IRB-approved study. All patients received 5-6 cycles of NAC followed by surgery. A good response was defined as ≤ 10% viable cells on histological analysis of the surgical specimen. DCE-MRI was performed before treatment (MRI0) and after two cycles (MRI1). Images were obtained every 8 s. Change in contrast enhancement (CE) between MRI0 and MRI1 was calculated for each acquisition delay ‘t’ on the whole tumor volume. Area under the receiver-operating characteristics curves (AUROC) for change in CE was calculated at each acquisition delay, as well as the accuracy of the Choi criteria.ResultsThere were 22 (73.3%) poor responders. Acquisition delay had a significant effect on change in CE and on the response status according to Choi (p = 0.0014 and 0.0270, respectively). The highest AUROC was obtained at t = 58 s (0.792) with an optimal threshold of a -30.5% decrease in CE. At t = 58 s, accuracy to predict a poor response was 82.8% above this threshold, while it was 72.4% and 70% with no objective response according to the Choi criteria and RECIST1.1, respectively.ConclusionOptimization of acquisition delay after injection to estimate change in CE improves the prediction of histological response. For STS undergoing NAC, a 60-s delay can be recommended with MRI.Key points• Accuracy of response criteria based on contrast enhancement, like the Choi criteria, is dependent on the acquisition delay after gadolinium-chelate injection.• DCE-MRI helps determine the optimal acquisition delay after gadolinium-chelate injection for improving evaluation of tumor response.• In soft tissue sarcoma, an acquisition delay at 60 s optimizes the evaluation of the response and accuracy of the Choi criteria.