Afshin Gangi

Injection of alcohol into bone metastases under CT guidance

Objective Percutaneous injection of ethanol was evaluated in terminally ill cancer patients with painful osteolytic bone metastases treated previously without success by radiation or chemotherapy and conventional pain therapy. Methods and Materials Twenty-five patients with 27 bone metastases in various locations underwent one to three instillations of 3–25 ml ethanol (95%) under CT guidance, which allowed precise needle positioning and control of the diffusion of alcohol thus minimizing the complications. Results Within 24 to 48 h 74% of the cases experienced a reduction of analgesic needs. Conclusion Percutaneous ethanol injection under CT guidance is useful in reducing pain and in improving the quality of life of patients with advanced stages of cancer and painful bone metastases.

Quality Assurance Guidelines for Percutaneous Vertebroplasty

Vertebral compression fracture is the reduction in individual vertebral body height by 20% or 4 mm [7]. PVP is a therapeutic, image-guided procedure that involves injection of radio-opaque cement into a partially collapsed vertebral body, in an effort to relieve pain and provide stability.

Percutaneous Bone Tumor Management

Interventional radiology plays a major role in the management of bone tumors. Many different percutaneous techniques are available. Some aim to treat pain and consolidate a pathological bone (cementoplasty); others aim to ablate tumor or reduce its volume (sclerotherapy, thermal ablation). In this article, image-guided techniques of primary and secondary bone tumors with vertebroplasty, ethanol injection, radiofrequency ablation, laser photocoagulation, cryoablation, and radiofrequency ionization (coblation) will be reviewed. For each modality, the principles, the indications, and the results will be presented. The technical choice depends on the therapeutic intent-curative or palliative-and the need for consolidation, but also on the general status of the patient and the other therapeutic options. For the most complex cases, combined treatments can be required. However, the less disabling technique should always be considered first.

IN VIVO STUDY OF FORCES DURING NEEDLE INSERTIONS

Percutaneous procedures are among the developing minimally invasive techniquesto treat cancerous diseases of the digestive system. They require a very accuratetargeting of the organs, achieved by the combination of tactile sensing and medicalimaging. In this paper, we study the forces involved during in vivo percutaneousprocedures for the development of a force feedback needle insertion robotic systemas well as the development of a realistic simulation device. The paper presentsdi erent conditions (manual and robotic insertions) and di erent organs (liver andkidney). Finally, we review some bio-mechanical models of the literature in thelight of our measurements.

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.

Saline-Infused Bipolar Radiofrequency Ablation of High-Risk Spinal and Paraspinal Neoplasms

OBJECTIVE We present three cases of symptomatic high-risk metastases involving the vertebral body treated using infused bipolar radiofrequency ablation either alone or in combination with vertebroplasty. CONCLUSION In our experience, the bipolar technique can reduce the risk of spinal cord damage in radiofrequency ablation of lesions within 1 cm of neural structures and involving paravertebral soft tissue.

Thermal Ablation of Spinal Osteoid Osteomas Close to Neural Elements: Technical Considerations

OBJECTIVE The purpose of this study was to evaluate experience with and determine the efficacy and safety of thermal ablation in the management of spinal osteoid osteomas close to neural elements. MATERIALS AND METHODS The records of all patients with osteoid osteomas of the spine managed with thermal ablation at two academic centers from 1993 to 2008 were reviewed. RESULTS Seventeen patients (13 male patients, four female patients; mean age, 25.9 years) had lesions in the lumbar (seven patients), thoracic (six patients), cervical (three patients), and sacral (one patient) regions of the spine. Two lesions were in the vertebral body, one was within the dens, and the others were in the posterior elements. The mean lesion diameter was 8.8 mm, and the mean distance between the lesion and the closest neural element was 4.3 mm. The lesions were managed with laser (13 lesions) or radiofrequency (four lesions) ablation. Special thermal protection techniques involving the epidural injection of gas or cooled fluid were used. Pain levels were assessed immediately before the procedure and on the day after the procedure. Long-term follow-up findings were available for 11 patients. No complications were encountered, and all patients reported relief of pain. The 11 patients who participated in long-term follow-up reported continued relief of pain. CONCLUSION Percutaneous thermal ablation can be used to manage spinal osteoid osteomas close to the neural elements. Special thermal protection techniques may add a margin of safety.

Radiofrequency ablation of hepatic tumors: simulation, planning, and contribution of virtual reality and haptics.

For radiofrequency ablation (RFA) of liver tumors, evaluation of vascular architecture, post-RFA necrosis prediction, and the choice of a suitable needle placement strategy using conventional radiological techniques remain difficult. In an attempt to enhance the safety of RFA, a 3D simulator, treatment planning, and training tool, that simulates the insertion of the needle, the necrosis of the treated area, and proposes an optimal needle placement, has been developed. The 3D scenes are automatically reconstructed from enhanced spiral CT scans. The simulator takes into account the cooling effect of local vessels greater than 3 mm in diameter, making necrosis shapes more realistic. Optimal needle positioning can be automatically generated by the software to produce complete destruction of the tumor, with maximum respect of the healthy liver and of all major structures to avoid. We also studied how the use of virtual reality and haptic devices are valuable to make simulation and training realistic and effective.

In Vivo Model Estimation and Haptic Characterization of Needle Insertions

During percutaneous interventions, the haptic perception of transitions and ruptures in the tissues is fundamental. In the medical robotics context, these events should be conveyed to a remote telemanipulating practitioner or should be taken into account in a robotic control scheme. However, this problem is extremely complex given the nature and the variety of tissues involved in percutaneous procedures. In this article, in vivo percutaneous experiments associated with an online model estimation of the interaction between tissues and a surgical needle are presented for the first time. The estimation scheme is then used to provide a robust method to automatically detect the transitions that occur during needle insertion. Finally, the principle of a modified teleoperation scheme that would allow better haptic discrimination of ruptures is proposed and illustrated.

Percutaneous thermal ablation: how to protect the surrounding organs.

A variety of thermal ablation techniques have been advocated for percutaneous tumor management. Although the above techniques are considered safe, they can be complicated with unintended thermal injury to the surrounding structures, with disastrous results. In the present article we report a number of different insulation techniques (hydrodissection, gas dissection and balloon interposition, warming/cooling systems) that can be applied. Emphasis is given to the procedure-related details, and we present the advantages and drawbacks of the insulation techniques. We also provide tips on avoiding painful skin burns when treating superficial lesions. Finally, we point out the interest of temperature monitoring and how it can be achieved (use of thermocouples, fiberoptic thermosensors, or direct magnetic resonance imaging temperature mapping). The above thermal insulation and temperature monitoring techniques can be applied alone or in combination. Familiarity with these techniques is essential to avoid major complications and to increase the indications of thermal ablation procedures.