PURPOSE-Respiratory motion can be a complicating factor during image-guided interventions. The ability to reproduce breath-holds may facilitate safer needle-based procedures. The purpose of this study was to evaluate if respiratory biofeedback decreased variability among breath-holds and if the signals from the respiratory bellows belt can be used to measure target motion. MATERIALS AND METHODS-In phase 1 of the study, a respiratory bellows belt was applied to patients before image-guided interventional procedures. Belt stretch from respiratory motion was converted into voltage readings and displayed on a monitor as biofeedback. Patients were asked to perform inspiratory, expiratory, and midcycle breath-holds with and without the biofeedback. The variability in voltage readings between breath-holds with and without biofeedback was compared. In phase 2, the respiratory bellows belt was used during computed tomography (CT)-guided procedures with the patients blinded to the biofeedback. Voltage readings and CT series numbers were recorded as patients were asked to hold their breath during scans. The variability of CT z-axis targets was compared with the variability of voltage readings.RESULTS-A significant decrease in variability was found during expiratory breath-holds (P = . 0083) with trends toward significance with midcycle and inspiratory breath-holds. A positive correlation (Kendall τ = 0.5; P = .024) was shown between CT z-axis and belt stretch variability in subjects who received smaller doses of moderate sedation compared with those who received larger doses or general anesthesia.CONCLUSIONS-Biofeedback may help the patient to have a more consistent breath-hold. The belt could decrease the error and unpredictability from craniocaudal motion of targets during imageguided interventions.PATIENT respiratory motion can be a complicating factor when targeting a tumor for computed tomography (CT)-guided interventional procedures. Respiration-induced motion during the normal breathing cycle can result in significant shifts in tumor position, especially near the diaphragm, in the lung and abdomen (1). Consistent and reproducible breath-holds could reduce procedure time and the number of needle manipulations, promoting a safer procedure. Without a documented measure of their breath-hold position in the respiratory cycle, the patient cannot be expected to precisely reproduce similar pre-and intraprocedural breathholds. The air bellows belt measures chest wall or abdomen excursion and provides patients with visual biofeedback during their respiratory cycle.Address correspondence to J.K.L., National Institutes of Health, Building 10, Room 1C367A, 9000 Rockville Pike, Bethesda, MD 20892; E-mail: locklinj@cc.nih.gov. NIH Public Access MATERIALS AND METHODSIn the present study, a tool consisting of an air bellows belt (Philips Medical Systems, Cleveland, OH) attached to a visual feedback system shown to patients was evaluated for its ability to assist patients to more precisely reproduce preprocedural breath-hold...

A 45-year-old male with renal cell carcinoma secondary to von-Hippel Lindau (VHL) disease presented for radiofrequency ablation (RFA) of kidney tumors. Due to his prior history of several partial nephrectomies and limited renal reserve, RFA was chosen because of its relatively nephronsparing nature. A laser guidance device was used to help guide probe placement in an attempt to reduce procedure time and improve targeting accuracy. The device was successful at guiding needle placement, as both tumors were located with a single pass. Follow-up CT scan confirmed accurate needle placement, showing an area of coagulation necrosis covering the previously seen tumor. KeywordsRadiofrequency ablation; Laser guidance; Renal cell carcinoma; von-Hippel Lindau disease Navigation and guidance devices for CT-guided interventions have been relatively underutilized, however, they show promise for effectively and accurately assisting needle or probe placement. Multiple systems and techniques have been developed to assist CT-guided procedures [5][6][7][8][9], varying from the complex (robotics) [1], to the simple fluid-filled disk, to approximate planned needle angulations [2].Radiofrequency ablation (RFA) is becoming broadly available in the oncology community, and is being studied for kidney tumors with some degree of success. We have performed nearly 200 kidney tumor ablations, and we often rely upon nearby landmarks for accurate needle angle selection to treat radiographically occult tumors. Laser guidance was used to assist in RFA in a kidney tumor that was difficult to visualize by CT scan without contrast. Local ablative therapies rely upon extreme accuracy for successful outcomes. The device (SimpliCT, NeoRad AS, Norway) is free standing, portable, and independent of the CT gantry. It consists of a laser source mounted on an L-shaped track, which stands on a 3-wheel lockable base (Fig. 1). Laser guidance simplified radiofrequency probe angulation implementation, and also facilitated probe repositioning for a second burn, according to a treatment plan developed with pretreatment CT. The authors have no commercial interest in the device. Case ReportA 45-year-old male with a history of von Hippel-Lindau disease presented for radiofrequency ablation of 2 left-sided kidney tumors. VHL is an autosomal dominant disorder, characterized by the development of both benign and malignant tumors [3]. This patient had bilateral renal cell carcinoma, and had undergone a left partial nephrectomy in 1995, and a right partial nephrectomy in 1999. During a follow-up hospitalization in 2000, he was found to have regrowth of tumor in both kidneys. Percutaneous RFA of the left-sided lesions was attempted at that time, but the procedure was aborted secondary to inadequate visualization of the tumors.

Chloroquine is quinolone derivative known to exert dose-related retinal toxicity, albeit in a variable manner. It is thought that variability in the presentation of chloroquine retinopathy may be the result of perturbations in drug bioavailability subsequent to oral ingestion. In order to better understand the ramifications of bioavailability on the development of retinal injury subsequent to chloroquine use, this study investigated the relationship between retinal injury and chloroquine administration via intraperitoneal rather than oral administration. Four-week-old C57/6J mice underwent daily intraperitoneal injection of 10 mg kg(-1) chloroquine hydrochloride for a total of 62 days. Following treatment, tissue was fixed in preparation for analysis by light and transmission electron microscopy. Treated animals demonstrated marked abnormality of the outer retinal layers described as complete loss of the outer plexiform layer as well as photoreceptors and photoreceptor nuclei. The retinal pigmented epithelium demonstrated focal atrophy, loss of nuclei and pigment irregularity. Findings in the inner retina were notable for the loss of Müller cells and the presence of membranous cytoplasmic bodies. Retinae of control animals were entirely normal. In contrast to previous studies in the murine model examining chloroquine retinopathy subsequent to oral administration, this study suggests that intraperitoneal chloroquine administration facilitates retinal toxicity, presumably due to heightened drug absorption and bioavailability. It is posited that an increased rate of drug accumulation within the retina leads to an enhanced lysosomotrophic drug effect due to inability of the lysosome to compensate for chloroquine-induced elevation in pH through re-acidification of the intra-lysosomal content.