CT-guided Needle Placement Research Articles

Puncture Cube Patient-Mounted Navigation System versus Freehand Method for CT-Guided Needle Placement: Study on a Neoprene Covered Elliptical Cylinder Gelatin Phantom.

The study aims to show how the "Puncture Cube" (PC) (Medical Templates, Egg, Switzerland) compares to the freehand method (FHM) for CT-guided punctures. The PC is a patient-mounted disassemblable cube consisting of an upper and lower template with multiple holes each to predefine puncture trajectory. A total of 80 punctures (FHM in-plane, FHM off-plane, PC in-plane, PC off-plane) was performed by 4 radiologists on a target 9.1cm below surface level of a neoprene covered elliptical cylinder gelatin phantom. The PC was never disassembled. Evaluated parameters were procedure time, number of CT-scans, euclidean distance (ED) and normal distance (ND). Respective parameters of FHM and PC were compared using the Wilcoxon signed-rank test and Levene test with significance levels of 5%. PC achieved smaller ED and ND values after initial needle insertion without corrections for both in-plane and off-plane punctures (P > 0.05). Variance of initial NDs was off-plane significantly larger for FHM. Final ED after needle path corrections was smaller for FHM both in- and off-plane (P < 0.05). Final off-plane ND was significantly lower for FHM with no significant difference in final in-plane ND. FHM off-plane punctures were significantly faster. There was no significant difference in CT-scans between both methods. Utilizing the PC may improve initial needle positioning and safety especially off-plane. However, better final needle positioning after correction with the greater freedom of movement method may suggest need for disassembly of the cube.

Evaluation of augmented reality training for a navigation device used for CT-guided needle placement.

Numerous navigation devices for percutaneous, CT-guided interventions exist and are, due to their advantages, increasingly integrated into the clinical workflow. However, effective training methods to ensure safe usage are still lacking. This study compares the potential of an augmented reality (AR) training application with conventional instructions for the Cube Navigation System (CNS), hypothesizing enhanced training with AR, leading to safer clinical usage. An AR-tablet app was developed to train users puncturing with CNS. In a study, 34 medical students were divided into two groups: One trained with the AR-app, while the other used conventional instructions. After training, each participant executed 6 punctures on a phantom (204 in total) following a standardized protocol to identify and measure two potential CNS procedural user errors: (1) missing the coordinates specified and (2) altering the needle trajectory during puncture. Training performance based on train time and occurrence of procedural errors, as well as scores of User Experience Questionnaire (UEQ) for both groups, was compared. Training duration was similar between the groups. However, the AR-trained participants showed a 55.1% reduced frequency of the first procedural error (p > 0.05) and a 35.1% reduced extent of the second procedural error (p < 0.01) compared to the conventionally trained participants. UEQ scores favored the AR-training in five of six categories (p < 0.05). The AR-app enhanced training performance and user experience over traditional methods. This suggests the potential of AR-training for navigation devices like the CNS, potentially increasing their safety, ultimately improving outcomes in percutaneous needle placements.

Evaluation of Accuracy and Performance of a Novel, Fully Gantry Integrated 3D Laser System for Computed Tomography Guided Needle Placement: A Phantom Study.

The purpose of this phantom study was to compare the accuracy, speed and technical performance of CT guided needle placement using a conventional technique versus a novel, gantry integrated laser guidance system for both an expert and a novice. A total of 80 needle placements were performed in an abdominal phantom using conventional CT guidance and a laser guidance system. Analysis of pooled results of expert and novice showed a significant reduction of time (277 vs. 204 s, p = 0.001) and of the number of needle corrections (3.28 vs. 1.58, p < 0.001) required when using laser guidance versus conventional technique. No significant improvement in absolute (3.81 vs. 3.41 mm, p = 0.213) or angular deviation (2.85 vs. 2.18°, p = 0.079) was found. With either approach, the expert was significantly faster (conventional guidance: 207 s vs. 346 s, p < 0.001; laser guidance: 144 s vs. 264 s, p < 0.001) and required fewer needle corrections (conventional guidance: 4 vs. 3, p = 0.027; laser guidance: 2 vs. 1, p = 0.001) than the novice. The laser guidance system helped both the expert and the novice to perform CT guided interventions in a phantom faster and with fewer needle corrections compared to the conventional technique, while achieving similar accuracy.

8 Hybrid intracavitary and interstitial brachytherapy for cervical cancer in the outpatient setting

Image-guided hybrid intracavitary and interstitial brachytherapy (HBT) for the treatment of locally advanced cervical cancer may improve outcomes compared to intracavitary brachytherapy alone. Pain control is usually achieved with general anesthesia (GA), which increases both treatment duration and the risk of complications with each treatment. Here we detail the results of our institution's protocol with CT-guided interstitial needle placement, utilizing minimal sedation. A single-institutional database of patients who underwent HBT for cervical cancer from June 2018 to May 2020 was queried. Patterns of anesthesia usage, step-by-step procedural times, medication usage, and treatment-related complications were reviewed. All patients had a Smit sleeve placed in the OR under GA days before their first HBT treatment. Prior to HBT, patients received minimal sedation, composed of oral lorazepam and hydrocodone/acetaminophen. Tandem and ovoids were inserted and interstitial needles were placed under CT guidance. The patients were moved from the CT table to a surgical bed, and then to the radiation vault for treatment delivery. The applicator was then removed and vaginal packing was inserted if any bleeding occurred. A total of 244 implants were placed in 63 patients under minimal sedation. 61 patients (96.8%) tolerated the procedure, 2 (3.2%) required epidural anesthesia, and 0 required transition to GA. The median time for the entire procedure (CT room entry to exit of the HDR room) was 70.0 mins (mean 70.3 mins, range 54–100 mins). The median time for the interstitial needle insertion portion was 9.0 mins (mean 9.8 mins, range 4–24 mins). Bleeding occurred in 54 (22.1%) implants, which resolved after 3 minutes of vaginal packing (mean 3.33 mins, range 1–8 mins). Our outpatient HBT protocol was efficient and well-tolerated, with reasonable bleeding rates which were minimal and quickly resolved. HBT with minimal sedation was achievable at a high percentage (96.8%). The performance of HBT without GA may reduce treatment time, costs, and anesthesia-related adverse effects. Treatment with minimal sedation has the potential to enable more universal use of HBT, improve brachytherapy dosimetry, and enhance patient outcomes. Further investigation is warranted.

GSOR2 Presentation Time: 9:05 AM: Implementation of Hybrid Intracavitary and Interstitial Brachytherapy for Cervical Cancer in a Freestanding Clinic

<h3>Purpose</h3> Radiation therapy for locally-advanced cervical cancer consists of external beam radiation therapy and brachytherapy. While the recent introduction of image-guided brachytherapy and hybrid intracavitary and interstitial brachytherapy treatments (HBT) may potentially improve clinical outcomes, current literature describes the procedure requiring significant resources (such as general anesthesia, conscious sedation, and MRI-based treatment planning). With increases in treatment time and patient movements, there is greater potential for positional changes of the applicator and neighboring organs at risk (OAR), which can alter dosimetry. Furthermore, these resources might not be universally available to all radiation oncology centers that perform intracavitary cervical brachytherapy, potentially limiting the widespread implementation of HBT. Here we describe our experience with CT-guided interstitial needle placement in a typical freestanding outpatient setting, with an emphasis on minimization of patient movement and treatment duration. <h3>Materials and Methods</h3> All patients that were treated with HBT from June 2018 to May 2020 were included in this series. Initially, patients were taken to the operating room, for an exam under anesthesia and Smit sleeve placement by the radiation oncologist. The patients were determined to need interstitial brachytherapy either by exam under anesthesia, due to anatomy and tumor extent, or after the first brachytherapy treatment, due to dosimetry. All tandem, ovoid and needle insertions and HDR treatments were performed in a freestanding clinic, on the CT simulator table. The patients were treated using minimal sedation (oral lorazepam and oxycodone/acetaminophen). An indwelling urinary catheter was inserted into the bladder. The tandem and ovoids (Elekta) were inserted in the patient, and a vaginal balloon was substituted for packing. Multiple CT scans were performed while advancing the interstitial needles, the bladder was filled with 180 cc of diluted contrast, and a final CT scan was taken for planning purposes. The patients were shifted from the CT table to a surgical bed (single shift), and then transported to the treatment room while treatment planning was performed using Oncentra (Elekta) treatment planning software. After the treatment plan was approved, the bladder was refilled to 180 cc and treatment was delivered using a microSelectron HDR afterloader (Elekta). The applicator was removed and the patient was examined for bleeding. If any vaginal bleeding occurred, vaginal packing was inserted with pressure applied. Time stamps and clinical data were collected during each procedure. <h3>Results</h3> Sixty-three patients underwent placement of a total of 244 interstitial implants. The median time for the entire procedure, from the time of patient entry into the CT simulation room to exit of the HDR treatment room, was 70.0 minutes (mean 70.3, range 54-100). The median time after tandem and ovoid insertion to complete interstitial needle insertion was 9.0 minutes (mean 9.8, range 4-24), using median 2 needles (mean 1.93, range 1-3) and median 3 CT scans (mean 2.63, range 1-4). Bleeding occurred in 22.1% (54/244) of implants, which resolved after median 3 minutes (mean 3.33, range 1-8) of vaginal packing with pressure. All patients (100%) required only one total shift, from the CT table to the mobile surgical bed. <h3>Conclusions</h3> In our series, the interstitial insertion portion of the HBT added 9 minutes, with an overall procedure time of 70 minutes (including insertion, planning, treatment and removal). There was an acceptable bleeding rate which quickly resolved with vaginal packing and pressure. Combining intracavitary and interstitial implants using a hybrid applicator appears to be feasible, efficient and safe in an outpatient freestanding clinic. Further studies aimed at evaluating long-term toxicities and tumor control are warranted.

Comparison of a Robotic and Patient-Mounted Device for CT-Guided Needle Placement: A Phantom Study.

Background: Robotic-based guidance systems are becoming increasingly capable of assisting in needle placement during interventional procedures. Despite these technical advances, less sophisticated low-cost guidance devices promise to enhance puncture accuracy compared with the traditional freehand technique. Purpose: To compare the in vitro accuracy and feasibility of two different aiming devices for computed-tomography (CT)-guided punctures. Methods: A total of 560 CT-guided punctures were performed by using either a robotic (Perfint Healthcare: Maxio) or a novel low-cost patient-mounted system (Medical Templates AG: Puncture Cube System [PCS]) for the placement of Kirschner wires in a plexiglass phantom with different slice thicknesses. Needle placement accuracy as well as procedural time were assessed. The Euclidean (ED) and normal distances (ND) were calculated at the entry and target point. Results: Using the robotic device, the ND at the target for 1.25 mm, 2.5 mm, 3.75 mm and 5 mm slice thickness were 1.28 mm (SD ± 0.79), 1.25 mm (SD ± 0.81), 1.35 mm (SD ± 1.00) and 1.35 mm (SD ± 1.03). Using the PCS, the ND at the target for 1 mm, 3 mm and 5 mm slices were 3.84 mm (SD ± 1.75), 4.41 mm (SD ± 2.31) and 4.41 mm (SD ± 2.11), respectively. With all comparable slice thicknesses, the robotic device was significantly more accurate compared to the low-cost device (p < 0.001). Needle placement with the PCS resulted in lower intervention time (mean, 158.83 s [SD ± 23.38] vs. 225.67 s [SD ± 17.2]). Conclusion: Although the robotic device provided more accurate results, both guidance systems showed acceptable results and may be helpful for interventions in difficult anatomical regions and for those requiring complex multi-angle trajectories.

Abstract No. 270 Safety and performance of the EPIONE robotic assistance for CT-guided percutaneous needle placement in the abdomen: pre-clinical study in pigs

Abstract No. 270 Safety and performance of the EPIONE robotic assistance for CT-guided percutaneous needle placement in the abdomen: pre-clinical study in pigs

Robotic assistance for quick and accurate image-guided needle placement.

Computed tomography (CT) image-guided procedures including biopsy, drug delivery, and ablation are gaining increasing application in medicine. Robotic technology holds the promise for allowing surgeons, and other proceduralists, access to such CT-guided procedures by potentially shortening training, improving accuracy, decreasing needle passes, and reducing radiation exposure. We evaluated surgeon learning and proficiency for image-guided needle placement with an FDA-cleared robotic arm. Five out of six surgeons had no prior CT-guided procedural experience, while one had prior experience with freehand CT-guided needle placement. All surgeons underwent a 60-min training with the MAXIO robot (Perfint Healthcare, Redmond, WA). The robot was used to place needles into three different pre-specified targets on a spine model. Performance time, procedural errors, and needle placement accuracy were recorded. All participants successfully placed needles into the targets using the robotic arm. The average time for needle placement was 3:44 ± 1:43min. Time for needle placement decreased with subsequent attempts, with average third placement taking 2:29 ± 1:51min less than the first attempt. The average vector distance from the target was 2.3 ± 1.2mm. One error resulted in the need for reimaging by CT scan. No errant needle placement occurred. Surgeons (attending fellows and residents) without previous experience and minimal training could successfully place percutaneous needles under CT guidance quickly, accurately, and reproducibly using a robotic arm. This suggests that robotic technology may be used to facilitate surgeon adoption of CT image-guided needle-based procedures in the future.

Semiautomated robotic, CT-guided needle placement for postmortem CSF sampling – a Novel application of the Virtobot

The sampling of cerebrospinal fluid (CSF) for chemical analysis is usually performed by a freehand lumbar puncture in a routine clinical procedure, while the suboccipital region is used for postmortem examinations. We introduce a new application for a semiautomated robotic, computed tomography (CT)-guided needle placement for postmortem lumbar and suboccipital CSF sampling. Postmortem computed tomography (PMCT) imaging was performed, and the data were sent to a custom-made Virtopsy Control Center and Virtopsy Planning and Navigation Station. Needle trajectories were planned for both suboccipital and lumbar approaches. Coaxial introducer needles were fully inserted automatically by the robotic system. PMCT was repeated to verify correct placement of the needles. Subsequently, CSF samples were taken using a syringe. By using this new application, the puncture of the spinal canal and cerebellomedullary cistern could be accurately performed to within a millimeter. Thus, failure of puncture and iatrogenic injury of the medulla oblongata may be prevented, and the risk of infection is significantly reduced. An early analysis of the CSF sample allows for a risk assessment in regard to the subsequent autopsy. Our application allows for minimally invasive, fast, efficient and safe CSF sampling prior to autopsy, enabling an analysis for metabolic imbalance, infection, etc.

Methylene Blue/Collagen Mixture for CT-Guided Presurgical Lung Nodule Marking: High Efficacy and Safety

PurposeTo assess outcomes of computed tomography (CT)-guided methylene blue/collagen marking of preoperative lung nodules before video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS). Materials and MethodsA retrospective cohort study assessing 25 methylene blue/collagen solution CT-guided lung nodule localization procedures on 26 nodules in 25 patients was performed. The procedures were performed by a fellowship-trained radiologist 1–2 hours before scheduled surgery under local anesthesia. Approximately 4–6 ml of methylene blue/collagen solution was injected in a perinodular location under CT guidance with a 19-gauge trocar needle and along the track to the visceral pleural surface. Post-procedural CT images confirmed appropriate lung nodule location marking. ResultsPerinodular CT-guided trocar needle placement was achieved in all marking procedures (n = 26/26). Increased consolidation near the target nodule was also demonstrated in all patients on the post-procedural localized CT scans. One patient with moderate emphysema developed a small to moderate-sized pneumothorax (∼20%–30%), and an 8-Fr thoracentesis catheter was placed under CT guidance before surgery. There was no bleeding or hemoptysis in any patient. Methylene blue/collagen solution was readily visible by the thoracic surgeon in association with all target nodules. One patient required conversion to open procedure due to the proximal portion of the right lower lobe pulmonary artery segmental branch. Of the 26 identified nodules, pathology specimens confirmed the adequacy of nodule resection in all cases. ConclusionsPreoperative CT-guided methylene blue/collagen solution injection offers a safe and highly effective technique for marking subpleural lung nodules undergoing VATS or RATS.

Deep learning-based liver segmentation for fusion-guided intervention.

Tumors often have different imaging properties, and there is no single imaging modality that can visualize all tumors. In CT-guided needle placement procedures, image fusion (e.g. with MRI, PET, or contrast CT) is often used as image guidance when the tumor is not directly visible in CT. In order to achieve image fusion, interventional CT image needs to be registered to an imaging modality, in which the tumor is visible. However, multi-modality image registration is a very challenging problem. In this work, we develop a deep learning-based liver segmentation algorithm and use the segmented surfaces to assist image fusion with the applications in guided needle placement procedures for diagnosing and treating liver tumors. The developed segmentation method integrates multi-scale input and multi-scale output features in one single network for context information abstraction. The automatic segmentation results are used to register an interventional CT with a diagnostic image. The registration helps visualize the target and guide the interventional operation. The segmentation results demonstrated that the developed segmentation method is highly accurate with Dice of 96.1% on 70 CT scans provided by LiTS challenge. The segmentation algorithm is then applied to a set of images acquired for liver tumor intervention for surface-based image fusion. The effectiveness of the proposed methods is demonstrated through a number of clinical cases. Our study shows that deep learning-based image segmentation can obtain useful results to help image fusion for interventional guidance. Such a technique may lead to a number of other potential applications.

System for CT-guided needle placement in the thorax and abdomen: A design for clinical acceptability, applicability and usability.

Various systems exist for CT-guided needle placement in the thorax and abdomen, but widespread adoption is lacking. The goal of this work is to develop a system for precise needle placement with a design focus on clinical acceptability, applicability and usability. A system was outlined incorporating a needle guide on a mechanism with a remote centre of motion, manually placeable around the patient at the desired entry point and lockable by push-button to the CT table. System and patient are scanned for system-to-CT registration and target specification. The needle guide is automatically aimed at the target, for manual needle insertion to specified depth. A fully functional prototype was realized, achieving 1.2±0.6 mm placement error at 79.0±8.4 mm depth and 2.1±0.7 mm at 156.0±6.9 mm for 2×12 in- and out-of-plane punctures in a gelatin phantom. The system enables precise needle placement in a single insertion and is ready for its first clinical deployment.

Educational Exhibit Abstract No. 445 - Feasibility of utilizing CT- guided theraputic pudendal nerve block in treating pudendal neuralgia

Detail the indications, benefits, and procedural details of a therapeutic pudendal nerve block. Trauma, compression, or entrapment of the pudendal nerve along its course can produce chronic pelvic and perineal pain. Presenting symptoms can mimic a variety of dermatological, urological, and gynecological conditions making the initial diagnosis challenging. A variety of non-diagnostic tests are typically performed and ineffective treatments are attempted with no relief of patient’s symptoms. Even after a diagnosis is established, conservative treatment with physiotherapy and pharmacotherapy might fail to relief symptoms. Studies have found CT-guided pudendal nerve block to be a quick, safe, and effective procedure to diagnose and treat pudendal neuralgia. A local anesthetic injected adjacent to the nerve can provide immediate relief and subsequent treatments with steroid and or botox can be performed for maintenance therapy. Using CT-guided needle placement, a 26 gauge spinal needle is guided towards the pudendal bundle either between the sacrospinous and sacrotuberious ligaments or in the pudendal canal (Alcock’s canal). The needle tip is positioned adjacent to the pudendal nerve and a long acting local anesthetic, such as bupivacaine is administered. If patient’s symptoms resolve immediately, the procedure is found to be diagnostic for pudendal neuralgia and repeated one week apart for two more times. When the procedure is repeated, a corticosteroid, such as triamcinolone or methylprednisolone, is often administered concurrently for its anti-inflammatory effects. CT-guided pudendal nerve block is a safe and effective treatment for patient's with pudendal neuralgia. The procedure can be performed relatively quick for both diagnostic and therapeutic goals.

Virtobot 2.0: the future of automated surface documentation and CT-guided needle placement in forensic medicine

In this paper we present the second prototype of a robotic system to be used in forensic medicine. The system is capable of performing automated surface documentation using photogrammetry, optical surface scanning and image-guided, post-mortem needle placement for tissue sampling, liquid sampling, or the placement of guide wires. The upgraded system includes workflow optimizations, an automatic tool-change mechanism, a new software module for trajectory planning and a fully automatic computed tomography-data-set registration algorithm. We tested the placement accuracy of the system by using a needle phantom with radiopaque markers as targets. The system is routinely used for surface documentation and resulted in 24 surface documentations over the course of 11months. We performed accuracy tests for needle placement using a biopsy phantom, and the Virtobot placed introducer needles with an accuracy of 1.4mm (±0.9mm). The second prototype of the Virtobot system is an upgrade of the first prototype but mainly focuses on streamlining the workflow and increasing the level of automation and also has an easier user interface. These upgrades make the Virtobot a potentially valuable tool for case documentation in a scalpel-free setting that uses purely imaging techniques and minimally invasive procedures and is the next step toward the future of virtual autopsy.

Thoracoscopic resection of computed tomography-localized lung nodules in children

PurposeDetection and treatment of small lung nodules are important in managing pediatric cancer. We studied the effectiveness of preoperative localization of pulmonary nodules by CT-guided needle hook wire placement followed by thoracoscopic resection in children with cancer. MethodsWe reviewed records of patients who underwent thoracoscopic resection of lung nodules localized preoperatively with CT-guided needle and hook wire placement at our hospital between March 1999 and April 2010 for nodule characteristics and outcomes of procedure. ResultsThirty-seven patients (median age, 14years) with osteosarcoma or other cancers underwent thoracoscopic resection of needle-localized lung nodules. Lesion (median nodule size, 4mm) location was left lung (n=11), right lung (n=19), and bilateral (n=7). The procedure was successful in 36 (97.3%) patients. Five patients had a pneumothorax after localization but none required chest tube placement before thoracoscopy. All patients underwent thoracoscopy, but 4 required conversion to open thoracotomy. During thoracoscopic inspection, the hook wire slipped out of the lesion in 6 patients, of whom 1 needed thoracotomy to locate nodule. Lesions (malignant in 13 patients) were removed in all patients. Five patients with benign lesions had recurrent malignant lung nodules. ConclusionsThoracoscopic resection of preoperatively localized small lung nodules is a safe and effective procedure in children.

CT-guided procedures: evaluation of a phantom system to teach accurate needle placement

To evaluate the use of a phantom system to help teach the basic techniques of accurate CT-guided needle placement, thereby avoiding the risks associated with teaching on patients. Gelatine phantoms with five, 1.9 cm embedded spherical wooden targets were constructed. Four trainee operators performed 15 simulated biopsy procedures on the targets (series one) and repeated identical procedures 2 weeks later (series two). Statistical analysis of accuracy of needle placement and subject confidence were performed. Significant sequential improvement in axial plane angular error was noted with the average error decreasing by 0.33 degrees after every five procedures performed (95% CI: -0.58 to -0.08, p=0.01). Operator confidence indicated significant improvement both within each series and from series one to series two (95% CI: 0.08 to 1.17, p=0.025 and 95% CI: 0.00 to 0.58, p=0.05) respectively. However, variability in operator performance made statistically significant improvement in other variables unproven. Despite the study comprising a relatively small number of participants and procedures, it clearly demonstrated the effectiveness of teaching operators to perform CT-guided procedures using a phantom system. Needle placement accuracy significantly improved, with a reduction in axial angular error, and improved operator confidence without the risks associated with training on patients. Three of the operators in this study had never performed a CT-guided procedure previously, and their proficiency, after a relatively short but intense period of training, was impressive. The use of phantoms should be considered routinely for basic training of CT-guided needle placement.

Percutaneous laser-induced thermoablation (LIT) of non-resectable lung metastases and primary lung tumors: A preliminary evaluation of technical aspects and local efficiency

17106 Background: Surgical resection remains the standard of care for solitary lung metastasis from colorectal cancer or primitive lung tumors. Nevertheless only a small part of patients can be radically resected. Thermal ablation is a mini-invasive local treatment that can be considered an alternative approach in non-resectable lesions or inoperable patients. Methods: We present a consecutive series of thirteen patients treated with LIT from March 2004 to March 2005. Nine patients had a small (maximum diameter smaller than 5 cm) non-resectable lung carcinoma while four patients had a solitary metastasis from colorectal cancer. Median age was 70-yrs (range 55–87), male-female ratio was 2:1. After mild sedation and local anaesthesia, optical fibers were inserted directly into the tumor with CT-guided percutaneous needle placement. Each optical fiber was connected to a neodymium:yttrium-aluminium-garnet (ND:YAG) laser, which delivers concentrated light at a wave-length of 1064 nm, with a 5-Watt power and a 1800-Joule energy per single fiber. A minimum of two and a maximum of four needles were used, with a 5 to 8 mm distance from one needle to another. Results: All the patients tolerated LIT procedure well, developing a minimal pneumothorax, which did not require any treatment. Easy manageable local side-effects occurred in two cases (a mild self-limiting haemoptysis and a pleural empyema). Post-treatment CT-scan demonstrated complete thermonecrosis in all the lesions smaller than 3 cm and almost complete in the bigger ones (3 to 5 cm). All the patients are still alive, with a local tumor control rate of 100% at radiological follow-up: no local progression was observed in 10 pts with a follow-up of at least 12 months and in 3 pts with a follow-up of at least 6 months. Conclusions: Percutaneous LIT permitted a complete ablation of lung metastases and lung carcinomas with an optimal local tumor control rate at 1-year and a low complication rate. Complete necrosis was achieved only in lesions with maximum diameter smaller than 3 cm. No significant financial relationships to disclose.

Value of CT Volume Imaging for Optimal Placement of Radiofrequency Ablation Probes in Liver Lesions

To determine the value of multiplanar and volume-rendered modes of analysis versus axial imaging for the optimal placement of probes in spiral image computed tomography (CT)-guided radiofrequency (RF) ablation of liver lesions. Thirty-two malignant hepatic lesions in 21 patients with hepatocellular carcinoma (n = 10) or metastases (n = 11) were treated with percutaneous RF ablation. After axial CT-guided placement (biopsy mode) of the probe in the tumor, a contrast-enhanced spiral image set was obtained and data were viewed in contiguous axial sections and the multiplanar and volume-rendered modes. The position of the probe was characterized as "central," "marginal," or "outside," corresponding with its position in the lesion. Outside positioning was corrected before ablation was performed and, in cases of "marginal" positioning, the probe was redirected after initial ablative therapy in the same session. Multiplanar and volume-rendered analysis reclassified the needle position before 14 of 32 RF ablation procedures (44%; P =.0034, McNemar test). In 10 cases, probe positions considered "central" on biopsy-mode images were found to be "marginal" with multiplanar/volume-rendered analysis. In three cases, probe positions considered "marginal" on biopsy-mode images were found to be "outside" with multiplanar/volume-rendered analysis. In one lesion, multiplanar/volume-rendered analysis upgraded the probe position from "marginal" to "central." Comparison of multiplanar and volume-rendered analysis revealed no difference in probe positioning. The time requirements to obtain additional data were 159 seconds +/- 49 for multiplanar analysis and 434 seconds +/- 78 for volume-rendered analysis. A contrast-enhanced spiral CT image data set with multiplanar reformations to verify an optimal probe location after axial CT-guided needle placement should be obtained before RF ablation of liver lesions.

Symptomatic intraspinal synovial cysts: opacification and treatment by percutaneous injection.

Intraspinal synovial cysts are usually located in the lower lumbar spine in association with osteoarthritis of the facet joints, and they are most accurately diagnosed by using CT. Surgical removal of intraspinal synovial cysts implicated in the development of radiculopathy has resulted in symptomatic relief. A nonoperative method of treatment consists of CT-guided needle placement into the facet joint adjacent to the cyst, followed by injection of contrast material to show communication between the joint and the cyst and injection of corticosteroids. Three outpatients were treated in this fashion without complications. Complete relief of symptoms was achieved in two cases and partial relief was achieved in one. Follow-up CT scans performed 2 months after the procedure showed no change in the size of the cysts in two of the patients. A 6-month follow-up CT scan in the third patient, however, showed significant improvement in cyst size. These preliminary results suggest that this procedure is an alternative to surgical management of intraspinal synovial cysts.

CT-guided needle placement in the central nervous system: results in 146 consecutive patients

The authors present their experiences with 185 computed tomography (CT)-guided needle placement procedures in 146 consecutive patients. There was 100% accuracy in first-pass entry into the lesion using a needle guide; 100% success in drainage of intracranial abscesses; 100% success in palliative decompression of intracranial cystic lesions including tumor cysts; and 97% accuracy in histologic diagnosis of unknown lesions. CT-guided aspiration biopsy corrected clinically incorrect diagnoses and altered patient management in 23% of all cases biopsied. Tabulation of complications revealed 0% incidence of scalp infection, bone infection, dissemination of tumor, or dissemination of infection; 13.5% incidence of clinically insignificant postprocedural bleeding; and 0.5% incidence of serious postprocedural hemorrhage leading to death (one patient only). Transient hemipareses were observed in three of 22 procedures for implantation of 192Ir but in none of 163 procedures for aspiration biopsy alone.