F. Ibrahim, N.A. Abu Osman, J. Usman and N.A. Kadri (Eds.): Biomed 06, IFMBE Proceedings 15, pp. 232-235, 2007 www.springerlink.com © Springer-Verlag Berlin Heidelberg 2007 ---------------------------------------------------------------- IFMBE Proceedings Vol. 15 --------------------------------------------------------------- A quantitative study of post-biopsy radiofrequency cauterization C.A. Azlan 1 , N.F. Mohd. Nasir 2 , N.A. Kadri 3 , A.A. Saifizul 4 , K.H. Ng 1 , B.J.J. Abdullah 1 1 Department of Biomedical Imaging, University of Malaya, Kuala Lumpur, Malaysia 2 School of Mechatronics Engineering, Kolej Universiti Kejuruteraan Utara Malaysia, Perlis, Malaysia 3 Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia 4 Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia Abstract— Percutaneous image-guided needle biopsy is typically performed in highly vascular organs or in tumors with rich macroscopic and microscopic blood supply. The main risks related to this procedure are bleeding and implan- tation of tumor cells in the needle tract. From numerous con- ducted studies, it was found that heating the needle tract using a radiofrequency (RF) ablation system has a potential to minimize these effects. However, this solution requires the use of specially designed RF needles which would make the proce- dure relatively expensive and complicated. Thus, in order to solve this problem, we propose a simple solution by using readily available biopsy needles connected to an RF generator. In order to do so, we have designed and developed an adapter to interface between these two devices. A bovine liver has been used as a sample tissue for the experimental procedure. The delivery of the RF was varied by varying the values for deliv- ered power, power delivery duration, and insertion depth. The results showed that the size of the coagulation necrosis region is affected by all of the parameters tested. In general, the size of the region is enlarged with higher delivery of RF power, longer duration of power delivery, and shallower needle inser- tion. Keywords— RF ablation, biopsy needle interface I. INTRODUCTION Biopsy is a medical diagnostic test used to determine the structure and composition of tissue or cells. The procedure involves sampling cells or tissue from an organ or other part of the body using a specialized needle. Examination of the tissue sample is then performed using a microscope in order for a diagnosis to be made. The outcome of this procedure is a definitive method to test for the presence of a malignant tumor (cancerous) or to confirm if an abnormality is benign (not cancerous). Another important use of this procedure is to determine the causes of infections or inflammations that cannot be diagnosed with routine testing methods. The main risks related to this procedure are hemorrhage (bleeding) and implantation of tumor cells in the needle tract after the needle is withdrawn. Patients with cirrhosis or hepatic tumors are at greater risk of hemorrhagic complica- tions after biopsy, as are patients with uncorrected coagulo- pathy [1-2]. Hemorrhage has been reported to be one of the main concerns in biopsy procedures, occurring in up to 90% of patients following a percutaneous renal biopsy [3], which may require blood transfusion or other types of intervention. This risk may go undetected unless the patient undergoes subsequent imaging procedures or develops alterations in hemodynamic status as a result of blood loss. In order to minimize these problems, several approaches have been used and reported in the literature. These include trans- needle placement of steel coils [4], injection of fibrin [5], injection of gelatin particles and thrombin [6], and injection of fibrinogen and thrombin [7]. From the various studies conducted, it was found that RF cauterization of the needle tract using a coaxial system has a great potential [7-8] in safely minimizing these risks. The use of coaxial needle eliminated the risk of specimen injury, because RF ablation is routinely performed using an intro- ducer needle. This makes RF ablation as one of the thera- peutic option of choice, since it reduces bleeding during the procedure. Pritchard et al. [9] have developed a coaxial needle bi- opsy system that uses RF energy to cauterize the needle track following a biopsy, and found that the technique effec- tively reduced bleeding (Figure 1). The main limitation of the technique used is that it is proprietary in nature, and requires the use of specially designed RF needles, which would make the procedure relatively expensive and compli- cated. In order to solve this particular problem we have designed and developed a low cost and simple adapter to interface between the RF generator and the biopsy needle. II. MATERIALS AND METHODS A. Device We developed an adapter to interface between the avail- able RF generator and a commercial biopsy needle. The device allows the flow of alternating current (AC) with RF frequencies from RF generator to the biopsy needle and later to a large dispersive pad that acts as a grounding elec- trode. Current in RF frequency range passing through these two electrodes leads to ion agitation, which is then con- verted by into heat caused by the tissue impedance. This