Accurate Needle Placement Research Articles

Equine Review

Introduction: This edition of Equine Review looks at the value of continuous per rectum fluid infusion, treatment of dorsal spinous process impingement by interspinous ligament desmotomy, and the use of radiographic monitoring to improve accuracy of needle placement into the distal intertarsal joint.

Assessing the Accuracy of Ultrasound-Guided Needle Placement in Sacroiliac Joint Injections.

Mezian, Kamal MD, PhD; Sobotová, Karolína MD; Angerová, Yvona MD, PhD Author Information

Landmarks For Accurate Sphenopalatine Ganglion Block Via the Transnasal and Infrazygomatic Approaches: A Cadaveric Study

Abstract INTRODUCTION Sphenopalatine ganglion (SPG) block is used for a variety of craniofacial pain syndromes either through the transnasal route or via the infrazygomatic approach. Intraoperative imaging can identify the pterygopalatine fossa (PPF) but not the exact position of the SPG. Accurate localization of the SPG requires knowledge of the relevant anatomical landmarks. METHODS A total of 30 mid sagittal head and neck cadaveric sections were studied. The specimens were fixed in anatomical position and the morphometric data was collected to facilitate correct SPG localization via trans-nasal approach and infrazygomatic approach. The metrical parameters were taken with the help of a digital vernier caliper accurate up to 0.02 mm. RESULTS The sphenopalatine foramen (SPF) was located at an average distance of 55 mm from the anterior nasal spine at a mean angle of 22°. It was at or just superior to the midpoint of a line joining the skull base and the hard palate. The SPG was located 4 mm posterior and 4.7 mm lateral to the SPF at a mean distance of 6.3 mm from the SPF at an inclination of about 50° in both the sagittal and coronal planes. In the infrazygomatic approach, the SPG was between 4.5 and 6.3 cm from the skin and at an angle of about 7° posterior and inferior. These two angles were remarkable in being almost same for all specimens in both the measured planes. CONCLUSION These morphometric measurements will be of help to the clinician for accurate electrode or needle placement for SPG block and in avoiding complications related to inaccurate needle placement.

Ultrasound-Guided Lumbar Transforaminal Epidural Injections; A Single Center Fluoroscopic Validation Study.

To investigate the success rate (technical precision) of ultrasound-guided lumbar transforaminal epidural steroid injection, which was validated by conventional fluoroscopic technique. A total of 20 patients with unilateral single-level lumbar foraminal disc protrusion causing radiculopathy were enrolled. Using transforming route, the needle location was determined by an axial (transvers) view of the ultrasound with fluoroscopic confirmation. We determined the needle placement accuracy of ultrasound- guided lumbar transforaminal injections approach. The accuracy of ultrasound-guided interventions was 90% as confirmed by fluoroscopy. There were 2 failed cases at the L4-L5 level in the US-guided. The success rate in L5-S1 level was 100%, in L4-L5 level was 80% and in L3-L4 level was 100%. No complications were noted. Ultrasound-guided lumbar transforaminal epidural injections are accurate and feasible in clinical setting with an accuracy of 90% and no complications.

Open Source Platform for Transperineal In-Bore MRI-Guided Targeted Prostate Biopsy.

Accurate biopsy sampling of the suspected lesions is critical for the diagnosis and clinical management of prostate cancer. Transperineal in-bore MRI-guided prostate biopsy (tpMRgBx) is a targeted biopsy technique that was shown to be safe, efficient, and accurate. Our goal was to develop an open source software platform to support evaluation, refinement, and translation of this biopsy approach. We developed SliceTracker, a 3D Slicer extension to support tpMRgBx. We followed modular design of the implementation to enable customization of the interface and interchange of image segmentation and registration components to assess their effect on the processing time, precision, and accuracy of the biopsy needle placement. The platform and supporting documentation were developed to enable the use of software by an operator with minimal technical training to facilitate translation. Retrospective evaluation studied registration accuracy, effect of the prostate segmentation approach, and re-identification time of biopsy targets. Prospective evaluation focused on the total procedure time and biopsy targeting error (BTE). Evaluation utilized data from 73 retrospective and ten prospective tpMRgBx cases. Mean landmark registration error for retrospective evaluation was 1.88 ± 2.63 mm, and was not sensitive to the approach used for prostate gland segmentation. Prospectively, we observed target re-identification time of 4.60 ± 2.40 min and BTE of 2.40 ± 0.98 mm. SliceTracker is modular and extensible open source platform for supporting image processing aspects of the tpMRgBx procedure. It has been successfully utilized to support clinical research procedures at our site.

ThoraSite: A device to improve accuracy of lateral decompression needle and chest tube placement.

Multiple reports have detailed an unacceptably high error rate in the siting of decompression needles and tubes and describe associated iatrogenic injuries. The objective of the current study was to measure the accuracy of the novel ThoraSite template for identifying an acceptable intercostal space (ICS) for lateral needle or tube thoracostomy. Two trained operators used the ThoraSite to place radiopaque needles in the left and right lateral chests of 12 cadavers. An independent radiologist reviewed fluoroscopy images to determine the primary outcome: the ICS in which each needle was placed. Secondary outcomes were ICS's palpable through ThoraSite's Safe Zone; needle placement relative to the anterior axillary line (AAL) and midaxillary line (MAL); and percent correct placement (defined as the third, fourth, or fifth ICS from 1 cm anterior to the AAL to 1 cm posterior to the MAL). The six female and six male cadavers spanned 4 ft and 11 inches (150 cm) to 6 ft and 7 inches (201 cm), 80 lb (36 kg) to 350 lb (159 kg), and 16 kg/m to 42 kg/m body mass index. All 24 needles were placed in either the third (4 [17%] of 24 needles), fourth (10 [42%] of 24 needles), or fifth ICS (10 [42%] of 24 needles). In 10 (42%) of 24 assessments, two ICSs were palpable in ThoraSite's Safe Zone. All palpable ICSs were either the third (8 [24%] of 34), fourth (15 [44%] of 34); or fifth ICS (11 [32%] of 34). Twenty-three (96%) of 24 needles were inserted from 1 cm anterior to the AAL to 1 cm posterior to the MAL. Twenty-three (96%) of 24 needle placements were correct. ThoraSite use was associated with needle placement in the third, fourth, or fifth ICS in an area roughly spanning the AAL to MAL in anatomically diverse cadavers. By facilitating appropriate needle/tube placement, ThoraSite use may decrease iatrogenic injuries. Future study involving representative users may be useful to further evaluate ThoraSite accuracy. Therapeutic and care management, level IV.

Assessing the Accuracy of Ultrasound-Guided Needle Placement in Sacroiliac Joint Injections.

The aim of the study was to assess the accuracy of ultrasound-guided needle placement for sacroiliac joint injections. Institutional review board approval was gained for a prospective cohort study of 50 patients (N = 50). Study patients who were referred for sacroiliac joint injections for sacroiliac joint mediate pain and met inclusion/exclusion criteria were enrolled in the study. Each patient underwent needle placement with ultrasound guidance in the procedure suite. After the needle was placed with the ultrasound guidance, fluoroscopy was used to confirm correct placement via contrast injection confirming a sacroiliac joint arthrogram. The arthrogram was confirmed via the performing physician and radiologist. The placement of the needle with ultrasound guidance into the sacroiliac joint was confirmed successful in 96% (48/50) patients by fluoroscopic arthrogram. The two patients with unsuccessful arthrograms after initial placement of the needle with ultrasound were morbidly obese. There was intravascular uptake during the arthrogram of one patient who had a successful arthrogram. Ultrasound-guided injection of the sacroiliac joint is successful and accurate upon confirmation of fluoroscopic arthrogram and should be used as an imaging modality for needle guidance.

Electromagnetic navigation system combined with High-Frequency-Jet-Ventilation for CT-guided hepatic ablation of small US-Undetectable and difficult to access lesions

Objectives: To report the feasibility and efficacy of percutaneous ablation of small hepatic malignant tumors that are invisible on ultrasound and inaccessible using in-plane CT guidance, using a combination of high-frequency jet-ventilation (HFJV) and electromagnetic (EM) needle tracking.Methods: This study reviewed 27 percutaneous ablations of small hepatic tumors (<2 cm) performed using EM navigation-based probe placement and HFJV. All lesions were invisible on ultrasound and difficult to reach on CT requiring a double-oblique approach. The primary outcome was technical efficacy, defined as complete lesion coverage, and evaluated on contrast enhanced MRI after 3 and 6 months. Needle placement accuracy, the number of control CT acquisitions, procedure time, complications and radiation doses were assessed.Results: Twenty-one patients with 27 treated lesions (14 hepatocellular carcinomas and 13 metastases) were included in this study. Mean tumor size was 12 ± 5.7 mm. Thirty-three percent of the lesions were located on the hepatic dome. Complete ablation was obtained in 100% at the 3- and 6-month MRI follow-up. The ablation probe was correctly placed on the first pass in 96%, with a mean path-to-tumor angle of 7 ± 4 degrees and a mean tip-to-tumor distance of 22 ± 19mm. A readjustment for additional overlapping application resulted in complete treatment in 4 patients. Needle placement took a mean 23 ± 12 min with mean radiation doses of 558 mGy*cm. No major complications were reported.Conclusion: Percutaneous liver ablation of lesions that cannot be seen on US and requiring out-of-plane CT access can be successfully and safely treated using electromagnetic-based navigation and jet-ventilation.

Teaching FNA techniques and ultrasound guided FNA

Teaching FNA techniques and ultrasound guided FNA

Template for MR Visualization and Needle Targeting.

To improve the targeting accuracy and reduce procedure time in magnetic resonance imaging (MRI)-guided procedures, a 3D-printed flexible template was developed. The template was printed using flexible photopolymer resin FLFLGR02 in Form 2 printer® (Formlabs, Inc., Somerville, MA). The flexible material gives the template a unique advantage by allowing it to make close contact with human skin and provide accurate insertion with the help of the newly developed OncoNav software. At the back of the template, there is a grid comprised of circular containers filled with contrast agent. At the front of the template, the guide holes between the containers provide space and angular flexibility for needle insertion. MRI scans are initially used to identify tumor position as well as the template location. The OncoNav software then pre-selects a best guide hole for targeting a specific lesion and suggests insertion depth for the physician A phantom study of 13 insertions in a CT scanner was carried out for assessing needle placement accuracy. The mean total distance error between planned and actual insertion is 2.7mm, the maximum error was 4.78mm and standard deviation was 1.1mm. The accuracy of the OncoNav-assisted and template-guided needle targeting is comparable to the robot-assisted procedure. The proposed template is a low-cost, quickly-deployable and disposable medical device. The presented technology will be further evaluated in prostate cancer patients to quantify its accuracy in needle biopsy.

Point-of-care ultrasound-guided cannulation versus standard cannulation in haemodialysis vascular access: protocol for a controlled random order crossover pilot and feasibility study

BackgroundPoint-of-care ultrasound (POCUS) has been used in various vascular access contexts; however, to date, it has not been widely adopted in haemodialysis clinics. People with end-stage kidney disease receiving haemodialysis require an arteriovenous fistula (AVF), arteriovenous graft (AVG), or central venous access device (CVAD) in order to access their blood for therapy/treatment. Cannulation issues, such as haematoma and extravasation, related to AVFs and AVGs are common. This pilot and feasibility study will assess the feasibility of a randomised controlled trial aimed at evaluating whether POCUS-guided cannulation results in more successful and accurate AVF needle placement than the standard practice of blind cannulation.MethodsA controlled, random order crossover design will be used to evaluate two clinical conditions: (1) POCUS-guided cannulation and (2) standard practice of blind cannulation, when used by haemodialysis nurses. The feasibility of conducting this type of trial for these two clinical conditions will be assessed through recruitment, retention, and attrition rates; perceptions of acceptability; implementation measures; and assessment of methods of data collection. Clinical outcomes to be assessed are overall cannulation success on first attempt, accuracy of needle tip placement, number of extravasations, procedural time, and patient and nurse perceptions. The setting is a 16-chair dialysis unit in regional Australia. Participants will include adult haemodialysis patients with an AVF in situ for greater than 2 months and haemodialysis-trained registered nurses working full- or part-time. Clinical outcomes will be analysed using generalised linear mixed models. Feasibility data will be reported using descriptive statistics. Qualitative audio data will be digitally recorded, transcribed verbatim, and analysed using thematic analysis.DiscussionPoint-of-care ultrasound for cannulation has the potential to promote high-quality, safe nursing care and decrease cannulation damage for patients on haemodialysis. Due to the lack of evidence for patient benefit and its innovative and niche use in haemodialysis centres, POCUS is currently only specified in one international guideline. This study will inform sample size calculations for a future multi-site trial.Trial registrationAustralian New Zealand Clinical Trials Registry, (21/11/2017) ACTRN12617001569392

Real-time, image-based slice-to-volume registration for ultrasound-guided spinal intervention

Real-time fusion of magnetic resonance (MR) and ultrasound (US) images could facilitate safe and accurate needle placement in spinal interventions. We develop an entirely image-based registration method (independent of or complementary to surgical trackers) that includes an efficient US probe pose initialization algorithm. The registration enables the simultaneous display of 2D ultrasound image slices relative to 3D pre-procedure MR images for navigation.A dictionary-based 3D–2D pose initialization algorithm was developed in which likely probe positions are predefined in a dictionary with feature encoding by Haar wavelet filters. Feature vectors representing the 2D US image are computed by scaling and translating multiple Haar basis filters to capture scale, location, and relative intensity patterns of distinct anatomical features. Following pose initialization, fast 3D–2D registration was performed by optimizing normalized cross-correlation between intra- and pre-procedure images using Powell’s method. Experiments were performed using a lumbar puncture phantom and a fresh cadaver specimen presenting realistic image quality in spinal US imaging. Accuracy was quantified by comparing registration transforms to ground truth motion imparted by a computer-controlled motion system and calculating target registration error (TRE) in anatomical landmarks.Initialization using a 315-length feature vector yielded median translation accuracy of 2.7 mm (3.4 mm interquartile range, IQR) in the phantom and 2.1 mm (2.5 mm IQR) in the cadaver. By comparison, storing the entire image set in the dictionary and optimizing correlation yielded a comparable median accuracy of 2.1 mm (2.8 mm IQR) in the phantom and 2.9 mm (3.5 mm IQR) in the cadaver. However, the dictionary-based method reduced memory requirements by 47× compared to storing the entire image set. The overall 3D error after registration measured using 3D landmarks was 3.2 mm (1.8 mm IQR) mm in the phantom and 3.0 mm (2.3 mm IQR) mm in the cadaver. The system was implemented in a 3D Slicer interface to facilitate translation to clinical studies.Haar feature based initialization provided accuracy and robustness at a level that was sufficient for real-time registration using an entirely image-based method for ultrasound navigation. Such an approach could improve the accuracy and safety of spinal interventions in broad utilization, since it is entirely software-based and can operate free from the cost and workflow requirements of surgical trackers.

ECIRS (Endoscopic Combined Intrarenal Surgery) Versus Fluoroscopic-guided Renal Access during supine Percutaneous Nephrolithotomy (PCNL): A Comparative Study

Objective: To evaluate the intra- and post-operative outcomes of percutaneous renal access using either ECIRS (Endoscopic Combined Intrarenal Surgery) or fluoroscopic-guided renal access for supine percutaneous nephrolithotomy (PCNL). Methods: In our institute, over a 24-month period (April 2012 to March 2014), two surgeons performed a total of 68 PCNLs (not consecutive staghorn stone cases); 33 ECIRS and 35 fluoroscopically- guided access (FGA). All patient and calculi demographics were recorded, as well as intra-operative parameters and complication/secondary procedure rates. Results: We demonstrate that ECIRS offers rapid operating time (total procedure time 113 vs. 142 min, p<0.05), low complication rates (sepsis (0% vs. 5.8%), transfusion (0% vs. 8.6%) or bowel injury (0%)), with reduced in-patient stay (2 vs. 4 days, p<0.05) and high rates of stone clearance/residual fragments <4mm (3% vs. 25.7%, p<0.05) and low rate of secondary procedure (6.1% vs. 31.4%, p<0.05). Conclusion: ECIRS offers shorter operating times, with low complication rates, higher rates of stone clearance and a reduced requirement for secondary procedures in comparison to purely FGA. We envisage that this is due to a combination of quicker and more accurate needle placement, as well as the ability to perform concomitant FURS and laser stone fragmentation.

Development of a shoulder-mounted robot for MRI-guided needle placement: phantom study.

This paper presents new quantitative data on a signal-to-noise ratio (SNR) study, distortion study, and targeting accuracy phantom study for our patient-mounted robot (called Arthrobot). Arthrobot was developed as an MRI-guided needle placement device for diagnostic and interventional procedures such as arthrography. We present the robot design and inverse kinematics. Quantitative assessment results for SNR and distortion study are also reported. A respiratory motion study was conducted to evaluate the shoulder mounting method. A phantom study was conducted to investigate end-to-end targeting accuracy. Combined error considering targeting accuracy, respiratory motion, and structure deformation is also reported. The SNR study showed that the SNR changes only 2% when the unpowered robot was placed on top of a standard water phantom. The distortion study showed that the maximum distortion from the ground truth was 2.57%. The average error associated with respiratory motion was 1.32mm with standard deviation of 1.38mm. Results of gel phantom targeting studies indicate average needle placement error of 1.64mm, with a standard deviation of 0.90mm. Noise and distortion of the MR images were not significant, and image quality in the presence of the robot was satisfactory for MRI-guided targeting. Combined average total error, adding mounting stability errors and structure deformation errors to targeting error, is estimated to be 3.4mm with a standard deviation of 1.65mm. In clinical practice, needle placement accuracy under 5mm is considered sufficient for successful joint injection during shoulder arthrography. Therefore, for the intended clinical procedure, these results indicate that Arthrobot has sufficient positioning accuracy.

Needle placement errors: do we need steerable needles in interventional radiology?

PurposeAccurate and precise needle placement is of utmost importance in interventional radiology. However, targeting can be challenging due to, eg, tissue motion and deformation. Steerable needles are a possible solution to overcome these challenges. The present work studied the clinical need for steerable needles. We aimed to answer three subquestions: 1) What are the current challenges in needle placement? 2) What are allowable needle placement errors? and 3) Do current needles need improvement and would steerable needles add clinical value?MethodsA questionnaire was administered at the Annual Meeting of Cardiovascular and Interventional Radiology Society of Europe in 2016. In total, 153 respondents volunteered to fill out the survey, among them 125 (interventional) radiologists with experience in needle placement.Results1) Current challenges in needle placement include patient-specific and technical factors. Movement of the target due to breathing makes it most difficult to place a needle (90%). 2) The mean maximal allowable needle placement error in targeted lesions is 2.7 mm. A majority of the respondents (85%) encounter unwanted needle bending upon insertion. The mean maximal encountered unwanted needle bending is 5.3 mm. 3) Needles in interventional radiology need improvement, eg, improved needle visibility and manipulability, according to 95% of the respondents. Added value for steerable needles in current interventions is seen by 93% of the respondents.ConclusionSteerable needles have the potential to add clinical value to radiologic interventions. The current data can be used as input for defining clinical design requirements for technical tools, such as steerable needles and navigation models, with the aim to improve needle placement in interventional radiology.

Cadaveric Evaluation of Different Approaches for Quadratus Lumborum Blocks.

Background A quadratus lumborum (QL) block is an abdominal truncal block technique that primarily provides analgesia and anaesthesia to the abdominal wall. This cadaveric study was undertaken to compare the dye spread between different needle approaches for ultrasound-guided QL blocks in soft-embalmed cadavers. Methods After randomization, an experienced anesthesiologist performed two lateral, three posterior, and five alternative QL blocks on the left or right sides of five cadavers. The target injection point for the alternative approach was the lumbar interfascial triangle, same as that of conventional posterior QL block, with a different needle trajectory. For each block, 20 ml of dye solution was injected. The lumbar region and abdominal flank were dissected. Results Ten blocks were successfully performed. Regardless of the approach used, the middle thoracolumbar fascia was deeply stained in all blocks, but the anterior layer was less stained. The alternative approach was more associated with spread of injectate to the transversus abdominis and transversalis fascia plane. Despite accurate needle placement, all lateral QL blocks were associated with a certain amount of intramuscular or subcutaneous infiltration. Two posterior QL blocks showed a deeply stained posterior thoracolumbar fascia, and one of them was associated with obvious subcutaneous staining. The subcostal, iliohypogastric, and ilioinguinal nerves were mostly involved, but the thoracic paravertebral space and lumbar plexus were not affected in all blocks. Conclusions The alternative approach for QL blocks was able to achieve a comparable extent when compared to the conventional approach.

Reliability of Pressure Waveform Analysis to Determine Correct Epidural Needle Placement in Laboring Women

(Anaesthesia. 2017;72(7):840–844) Epidural failure is a significant problem in obstetric anaesthesia with one survey of parturients reporting a failure rate of 23%. There can be many causes of epidural failure, including technical failure due to misidentification of the epidural space. A false loss-of-resistance during epidural needle advancement is a common cause of misidentification. Pressure waveform analysis has been used to provide confirmation of correct epidural needle position when the loss-of-resistance technique was used to identify the epidural space during thoracic epidural procedures. Accurate needle placement is confirmed if a pulsatile waveform synchronized with arterial pulsations is seen. In one study, the failure rate decreased from 24% with loss-of-resistance only to 2% with the addition of pressure waveform analysis. However, the reliability of this technique for lumbar epidural analgesia for labor is unclear. This observational study was performed to determine the reliability of pressure waveform analysis in identifying accurate epidural needle placement during lumbar epidural insertion for labor analgesia.

Force Model for Ultrasonic Needle Insertion

A better understanding of needle-tissue interaction forces when needle is inserted into tissue during injection and minimally invasive surgery can lead to more accurate needle placement, better needle path planning, and better surgical simulation. In this study, a vibratory needle insertion force model is experimentally developed to explore the effect of ultrasonic amplitude on the insertion force. The maximum insertion force is comprised of three forces: tearing force, spreading force, and friction force. Ultrasonic vibration needle insertion experiments are performed on a tissue simulant to measure how vibratory parameters influence friction force, dynamic fracture toughness, and crack length. Results show that with the vibration amplitude changing from 0 to 517.2 μm, the maximum puncture force reduces up to 60.8%, the friction force reduces up to 80.7%, the dynamic fracture toughness of the phantom decreases up to 76.8%, and the crack length increases up to 325.8%. The increase in crack length created by the high amplitude vibration allows for the substantial decrease in frictional force.

Follow-up of negative MRI-targeted prostate biopsies: when are we missing cancer?

Multiparametric magnetic resonance imaging (mpMRI) has improved clinicians' ability to detect clinically significant prostate cancer (csPCa). Combining or fusing these images with the real-time imaging of transrectal ultrasound (TRUS) allows urologists to better sample lesions with a targeted biopsy (Tbx) leading to the detection of greater rates of csPCa and decreased rates of low-risk PCa. In this review, we evaluate the technical aspects of the mpMRI-guided Tbx procedure to identify possible sources of error and provide clinical context to a negative Tbx. A literature search was conducted of possible reasons for false-negative TBx. This includes discussion on false-positive mpMRI findings, termed "PCa mimics," that may incorrectly suggest high likelihood of csPCa as well as errors during Tbx resulting in inexact image fusion or biopsy needle placement. Despite the strong negative predictive value associated with Tbx, concerns of missed disease often remain, especially with MR-visible lesions. This raises questions about what to do next after a negative Tbx result. Potential sources of error can arise from each step in the targeted biopsy process ranging from "PCa mimics" or technical errors during mpMRI acquisition to failure to properly register MRI and TRUS images on a fusion biopsy platform to technical or anatomic limits on needle placement accuracy. A better understanding of these potential pitfalls in the mpMRI-guided Tbx procedure will aid interpretation of a negative Tbx, identify areas for improving technical proficiency, and improve both physician understanding of negative Tbx and patient-management options.

3:36 PM Abstract No. 215 Patient-specific needle guidance templates manufactured intraprocedurally for image-guided intervention

Multifocal or large tumors can be treated effectively using multiple ablation needles, but it is time consuming and difficult to perform accurately without frequent re-scanning or use of navigation systems. A new targeting method was developed using a custom patient-specific needle guide template, fabricated intraoperatively. In an IACUC approved study, a 78kg pig was studied under general anesthesia. Steel balls (1.5 mm) were implanted into the liver to serve as targets. Fiducial markers were affixed to the abdomen. A custom 150 × 220 mm plastic frame designed to hold two parallel plates was fixed over the abdomen using a rigid mounting arm. The frame and subject underwent CT scan with breath-hold. The targets, fiducial and frame were identified in the images. A preprocedure needle trajectory plan was created for each target, with defined skin entry sites and a path that avoided critical structures. The plan that included all needle paths was converted into a drilling program for an inexpensive numerical-controlled table-top milling machine, and the hole pattern corresponding to the planned trajectories was drilled into two plates. The plates were attached to the frame and needles were passed through the drilled holes toward the targets. After each needle placement, the animal was re-scanned to determine the accuracy of needle placement by determining the distance from needle tip to target. The system was also studied in similar fashion in static phantom experiments. The needle to target error distance for four live animal insertions was 3.2 (standard deviation, 1.8 mm) and ranged between 1.5 and 5.2 mm. The needle delivery technique was feasible for targeting multiple liver locations and facilitated complex oblique paths to the target. The planning step required approximately 5 minutes. The template was manufactured at bedside in 7.5 minutes. Accurate placement of multiple needles using a custom-drilled, patient-specific template (based on a preprocedure CT) is possible and can be performed in the scan room immediately prior to insertion. The system is similar in performance to more complex systems that require tracking.