A light-guidance system to be used for CT-guided biopsy

Fully Integrated Laser Guidance for CT-Based Punctures: A Study in Phantoms and Patients

PURPOSE

To test the hypothesis of equal or even superior applicability and accuracy of a fully integrated, laser-based computed tomography (CT) navigation system compared with conventional CT guidance for percutaneous interventions.

MATERIALS AND METHODS

CT-guided punctures were first performed in phantoms. Four radiologists with different experience levels (2 residents (L.B., C.D.) and 2 board-certified radiologists (B.M., K.R.) performed 48 punctures using both conventional image-guided and laser-guided approaches. Subsequently, 12 punctures were performed in patients during a clinical pilot trial. Phantom targets required an in-plane or a single-/double-angulated, out-of-plane approach. Planning and intervention time, control scan number, radiation exposure, and accuracy of needle placement (measured by deviation of the needle tip to the designated target) were assessed for each guidance technique and compared (Mann-Whitney U test and t test). Patient interventions were additionally analyzed for applicability in a clinical setting.

RESULTS

The application of laser guidance software in the phantom study and in 12 human patients in a clinical setting was both technically and clinically feasible in all cases. The mean planning time (P = .009), intervention time (P = .005), control scan number (P < .001), and radiation exposure (P = .013) significantly decreased for laser-navigated punctures compared with those for conventional CT guidance and especially in punctures with out-of-plane-trajectories. The accuracy significantly increased for laser-guided interventions compared with that for conventional CT (P < .001).

CONCLUSIONS

Interventional radiologists with differing levels of experience performed faster and more accurate punctures for out-of-plane trajectories in the phantom models, using a new, fully integrated, laser-guided CT software and demonstrated excellent clinical and technical success in initial clinical experiments.

AngleNav: MEMS Tracker to Facilitate CT-Guided Puncture

As a low-cost needle navigation system, AngleNav may be used to improve the accuracy, speed, and ease of CT-guided needle punctures. The AngleNav hardware includes a wireless device with a microelectromechanical (MEMS) tracker that can be attached to any standard needle. The physician defines the target, desired needle path and skin entry point on a CT slice image. The accuracy of AngleNav was first tested in a 3D-printed calibration platform in a benchtop setting. An abdominal phantom study was then performed in a CT scanner to validate the accuracy of the device's angular measurement. Finally, an in vivo swine study was performed to guide the needle towards liver targets (n = 8). CT scans of the targets were used to quantify the angular errors and needle tip-to-targeting distance errors between the planned needle path and the final needle position. The MEMS tracker showed a mean angular error of 0.01° with a standard deviation (SD) of 0.62° in the benchtop setting. The abdominal phantom test showed a mean angular error of 0.87° with an SD of 1.19° and a mean tip-to-target distance error of 4.89 mm with an SD of 1.57 mm. The animal experiment resulted in a mean angular error of 6.6° with an SD of 1.9° and a mean tip-to-target distance error of 8.7 mm with an SD of 3.1 mm. These results demonstrated the feasibility of AngleNav for CT-guided interventional workflow. The angular and distance errors were reduced by 64.4 and 54.8% respectively if using AngleNav instead of freehand insertion, with a limited number of operators. AngleNav assisted the physicians to deliver accurate needle insertion during CT-guided intervention. The device could potentially reduce the learning curve for physicians to perform CT-guided needle targeting.

CT-guided biopsy of thoracic lesions with a novel wire-based needle guide device - initial experiences

BACKGROUND

Biopsies guided by computed tomography (CT) play an important role in clinical practice. A short duration, minimal radiation dose and complication rate are of particular interest. Purpose To evaluate the potential of a novel self-manufactured wire-based needle guide device for CT-guided thoracic biopsies with respect to radiation dose, intervention time and complication rate.

MATERIAL AND METHODS

Forty patients that underwent CT-guided biopsies of thoracic lesions were included in this study and assigned to two groups. Patients in group A (n = 20, mean age 69 ± 8.4 years) underwent biopsies with a novel wire-based needle guide device, while patients in group B (n = 20, mean age 68.4 ± 10.1 years) were biopsied without a needle guide device. The novel self-manufactured needle guide device consists of an iron/zinc wire modelled to a ring with a flexible arm and an eye at the end of the arm to stabilize the biopsy needle in the optimal position during intervention. Predefined parameters (radiation dose, number of acquired CT-slices, duration of intervention, complications) were compared between both groups.

RESULTS

Mean radiation dose (CTDIvol 192 mGy versus 541 mGy; P ≤ 0.001) and the number of acquired slices during intervention (n = 49 ± 33 vs. n = 126 ± 78; P ≤ 0.001) were significantly lower in group A compared with group B. Intervention time in group A (13.1 min) was significantly lower than in group B (18.5 min, P < 0.01). A pneumothorax as peri-interventional complication was observed less frequent after device assisted biopsies (n = 4 vs. n = 8, n.s.).

CONCLUSION

The novel wire-based needle guide device is a promising tool to facilitate CT-guided thoracic biopsies reducing radiation dose, intervention time, and related complications. Further studies are mandatory to confirm these initial results.

Laser-guided computed tomography puncture system: simulation experiments using artificial phantom lesions and preliminary clinical experience

PURPOSE

To conduct computed tomography (CT)-guided puncture exactly and safely, we newly developed a laser guiding puncture system that can be used in a commercially available CT scanner.

MATERIALS AND METHODS

The laser-guided CT puncture system is built on the CT table with an aluminum frame. Preliminary simulation tests were conducted using two models representing the body and nodular lesions, and puncture procedures were carried out for 15 patients using this system.

RESULTS

The mean distance and standard deviation from the center in simulation experiments conducted using this puncture system were 2.95 +/- 1.20 mm for operator A and 3.52 +/- 1.12 mm for operator B. There was no statistically significant difference between the operators (P = 0.40) or the angles (P = 0.32). For five lung biopsy patients, the distance from the target point planned before biopsy to the actual last puncture point was 0-8 mm. For 10 percutaneous vertebroplasty (PVP) patients (two performed in Th11, one in Th12, five in L1, two in L2), the plan before the puncture procedure was to pass the needle through the vertebral pedicle in all cases. The distance between the planned target point and the actual last puncture point was 0-5 mm.

CONCLUSION

This system has the potential to accomplish the CT-guided puncture procedure safely and accurately.

Computed-tomography-guided punctures using a new guidance device

PURPOSE

To evaluate a new adjunctive guidance device, a puncture guide, constructed to simplify computed tomography (CT)-guided punctures and to make the procedure more accurate and safe.

MATERIAL AND METHODS

17 patients referred for CT-guided punctures were included in the study. There were 10 thoracic and 7 abdominal or pelvic lesions with a mean maximum diameter of 29 +/- 18 mm. All punctures were performed using a laser guide combined with the new device. The needle guide created a streak artefact in the image, indicating the needle path.

RESULTS

The puncture was successful at the first attempt in 15 of the 17 patients. The artefact was visible in all patients, and in the majority there was a distinct artefact reaching from the entry point to the lesion. The deviation between the angle of the streak artefact and the final angle of the needle was 1.1 degrees.

CONCLUSION

The benefits of the puncture guide were the artefact pointing at the target, the needle support, and accuracy when performing CT-guided punctures.

A navigation system for minimally invasive CT-guided interventions

The purpose of our project was to develop a novel navigation system for interventional radiology. Fields of application are minimally invasive percutaneous interventions performed under local anaesthesia. In order to reduce unintentional patient movements we used a patient vacuum immobilization device. Together with the vacuum fixation and a newly developed reference frame we achieved a fully automatic patient-to-image registration independent from the tracking system. The combination of the software and a novel designed needle holder allows for an adjustment of the needle within a few seconds. The complete system is adapted to the requirements of the radiologist and to the clinical work-flow. For evaluation of the navigation system we performed a phantom study with a perspex phantom and achieved an average needle positioning accuracy of less than 0.7 mm.

Laser navigation for radiofrequency ablation

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 nephron-sparing 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.

A whole-body registration-free navigation system for image-guided surgery and interventional radiology

RATIONALE AND OBJECTIVES

To develop and test an image-guided navigation system in which the base of reference is taken from the imaging modality, here, a helical CT scanner.

METHODS

An optical digitizer together with a calibration device is used to measure the transformation matrix between the digitizer reference system and a CT reference system. During intervention, it tracks radiological and surgical tools with tool references. A specific software visually integrates the current tool position with the corresponding image information. In vitro accuracy tests were performed.

RESULTS

With helical CT, freehand positioning accuracy was 1.9 +/- 1.1 mm (mean +/- SD) in vitro (n = 718).

CONCLUSIONS

The navigation system developed by the authors appears to be feasible for radiological interventions as well as for minimally invasive surgery. It is not limited to a certain procedure, can be used in every region of the body, and is functional after imaging. Intraprocedural scans can be integrated immediately.

CT-guided intervention using a patient laser marker system

To prove the usefulness of a simple laser marker system (LMS) in target definition as well as examination procedure for CT-guided interventions, 130 cases of diagnostic biopsies and lumbal sympathectomies were compared. In 75 cases LMS and in 55 cases a simple crossgrid was used. Taking advantage of the LMS, the parameters of intervention (cutaneous location, length, and angle) can be planned, exactly demonstrated, and it is possible to check the needle position during the whole procedure. Thus, the number of necessary control scans decreased to 30%, and corrections of needle location were reduced to approximately 30%. Moreover, the average target deviation of the needle decreased below 5 mm in 50% of cases, and the duration of interventional procedure was reduced considerably. It can be concluded that LMSs are recommended in CT-guided interventions for quality assurance, dose reduction, and improvement of handling. It will be especially advantageous in cases of small target volume, oblique needle path, and tilted gantry.

Accuracy of CT biopsy: laser guidance versus conventional freehand techniques

RATIONALE AND OBJECTIVES

The purpose of this study was to determine whether laser-guided computed tomographic (CT) biopsy is more accurate than CT-guided biopsy with conventional freehand techniques.

MATERIALS AND METHODS

Two independent operators performed an equal number of freehand and laser-guided needle passes at varying single and double angles (0 degree, 30 degrees, 60 degrees, 25 degrees/30 degrees, and 25 degrees/60 degrees) on targets within six pork and beef phantoms. A total of 180 biopsy passes were performed, and error distances of needle tip to target were tabulated. Data were analyzed by means of repeated measures analysis of variance (ANOVA) to compare the accuracy of laser guidance with freehand passes. ANOVA and correlation analysis were also used to confirm the relative equivalency of phantom targets and biopsy parameters.

RESULTS

Overall, laser-guided passes were statistically significantly more accurate than freehand passes. Mean error with laser guidance was 5.01 mm (standard error [SE] = 0.41 mm), whereas mean error with freehand techniques was 10.58 mm (SE = 0.82 mm) (F = 52.0, df = 1.17, P = .0001). Ninety-three percent of laser-guided passes and 56% of freehand passes were within 1 cm of the intended target. Error increased for both laser-guided and freehand techniques with larger angles or double-angle biopsies, but the increases were greater with freehand technique. No statistically significant differences existed between the targets themselves or biopsy parameters for the two operators.

CONCLUSION

Laser-guided CT biopsies were more accurate than freehand CT biopsies. Practical advantages of laser guidance over freehand CT biopsy methods may include decreased procedure times and reduced patient morbidity.

Belt device for simplified CT-guided puncture and biopsy: a technical note

A new radiolucent device for increased accuracy of CT-guided fine-needle punctures permits precise determination of the optimum angle, depth, and position of the fine needle, which can be preset from the data supplied on the CT monitor. Puncture and repeat scans for controlling the tip of the needle can be performed with the patient in a stationary position. The device is designed as a belt that holds a needle holder sheath and a goniometric scale, both of which can be moved to varying positions around the patient.