Technology improvements for image-guided and minimally invasive spine procedures

Outcomes and technical issues of transcorporeal anterior cervical microforaminotomy in patients with cervical brachialgia

INTRODUCTION

Transcorporeal anterior cervical microforaminotomy is a motion-preserving surgery. It addresses directly to the prolapsed disc in contrast to posterior laminoforaminotomy and does not affect facet joints; in the transuncal approach, there is a chance of vertebral artery injury and it also decreases disc height; hence, may alter the motion of that segment.

OBJECTIVE

Aim is to assess the outcome of surgery and its effectiveness.

METHODS

A total of 40 patients were observed retrospectively of which 33 were male and 7 were female. A single study of transcorporeal anterior cervical microforaminotomy was analyzed in a private hospital (Comfort Hospital), Dhaka, Bangladesh. Patients having pure brachialgia who were not relieved by conservative treatment over 6-8 weeks in cervical disc prolapse were included in the study. Patients having more than one level of disease, features of myelopathy, or instability were excluded from the study.

RESULTS

All patients were pain-free postoperatively, although after one to two months 2 out of 40 patients developed brachialgia and required anterior cervical discectomy and fusion.

CONCLUSION

Transcorporeal microforaminotomy for brachialgia is a safe and effective approach that is motion preserving and minimally invasive as well.

Feasibility, safety and accuracy of a CT-guided robotic assistance for percutaneous needle placement in a swine liver model

Evaluate the feasibility, safety and accuracy of a CT-guided robotic assistance for percutaneous needle placement in the liver. Sixty-six fiducials were surgically inserted into the liver of ten swine and used as targets for needle insertions. All CT-scan acquisitions and robotically-assisted needle insertions were coordinated with breath motion using respiratory monitoring. Skin entry and target points were defined on planning CT-scan. Then, robotically-assisted insertions of 17G needles were performed either by experienced interventional radiologists or by a novice. Post-needle insertion CT-scans were acquired to assess accuracy (3D deviation, ie. distance from needle tip to predefined target) and safety. All needle insertions (43/43; median trajectory length = 83 mm (interquartile range [IQR] 72–105 mm) could be performed in one (n = 36) or two (n = 7) attempts (100% feasibility). Blinded evaluation showed an accuracy of 3.5 ± 1.3 mm. Accuracy did not differ between novice and experienced operators (3.7 ± 1.3 versus 3.4 ± 1.2 mm, P = 0.44). Neither trajectory angulation nor trajectory length significantly impacted accuracy. No complications were encountered. Needle insertion using the robotic device was shown feasible, safe and accurate in a swine liver model. Accuracy was influenced neither by the trajectory length nor by trajectory angulations nor by operator’s experience. A prospective human clinical trial is recruiting.

Use of a radiopaque localizer grid and methylene blue staining as an aid to reduce radiation exposure

Background: Localization of small femur lesions for resection can be challenging and may be associated with the need for significant fluoroscopic imaging and tissue dissection. This study was performed to evaluate the use of a radiopaque localizer grid along with methylene blue staining for resection of small femur lesions in children, and to determine the effectiveness of this effectiveness at reducing radiation exposure and tissue injury.Material and methods: A radiopaque localizer grid was used to identify the body surface site of bone lesions, and then 0.02-0.03 mL of methylene blue was injected into the bone lesions. After skin incision, the blue bone tissue was found and complete lesion resection performed.Results: A radiopaque localizer grid was utilized to plan the point of entry for lesion resection. The average operation time was shorter, and the C-arm was used less frequently, and the incision length was shorter in the grid and methylene blue group compared with the control group.Conclusion: A radiopaque localizer grid is a simple and practical device for efficient localization of the skin entry site, and methylene blue accurately pinpoints bone lesions, reducing radiation exposure and tissue injury.

Computed Tomography-Guided Biopsy for Potts Disease: An Institutional Experience from an Endemic Developing Country

Study Design

A retrospective chart review.

Purpose

In endemic resource poor countries like Pakistan, most patients are diagnosed and treated for Potts disease on clinical and radiological grounds without a routine biopsy. The purpose of this study was to evaluate the use and effect of computed tomography (CT)-guided biopsy in the management of Potts disease since the technique is becoming increasingly available.

Overview of Literature

CT-guided biopsy of spinal lesions is routinely performed. Literature on the utility of the technique in endemic resource poor countries is little.

Methods

This study was conducted at the Neurosurgery section of Aga Khan University Hospital Karachi. All the patients with suspected Potts disease who underwent CT-guided biopsy during the 7 year period from 2007 to 2013 were included in this study. Details of the procedure, histopathology and microbiology were recorded.

Results

One hundred and seventy-eight patients were treated for suspected Potts disease during the study period. CT-guided biopsies of the spinal lesions were performed in 91 patients (51.12%). Of the 91 procedures, 22 (24.2%) were inconclusive because of inadequate sample (10), normal tissue (6) or reactive tissue (6). Sixty-nine biopsies were positive (75.8%). Granulomatous inflammation was seen in 58 patients (84.05%), positive acid-fast bacillus (AFB) smear in 4 (5.7%) and positive AFB culture in 12 patients (17.3%). All 91 cases in which CT-guided biopsy was performed responded positively to antituberculosis therapy (ATT).

Conclusions

75.8% of the specimens yielded positive diagnoses. Granulomatous inflammation on histopathology was the commonest diagnostic feature. In this series, the rates of positive AFB smear and culture were low compared to previous literature.

Robotic-assisted thermal ablation of liver tumours

OBJECTIVE

This study aimed to assess the technical success, radiation dose, safety and performance level of liver thermal ablation using a computed tomography (CT)-guided robotic positioning system.

METHODS

Radiofrequency and microwave ablation of liver tumours were performed on 20 patients (40 lesions) with the assistance of a CT-guided robotic positioning system. The accuracy of probe placement, number of readjustments and total radiation dose to each patient were recorded. The performance level was evaluated on a five-point scale (5-1: excellent-poor). The radiation doses were compared against 30 patients with 48 lesions (control) treated without robotic assistance.

RESULTS

Thermal ablation was successfully completed in 20 patients with 40 lesions and confirmed on multiphasic contrast-enhanced CT. No procedure related complications were noted in this study. The average number of needle readjustment was 0.8 ± 0.8. The total CT dose (DLP) for the entire robotic assisted thermal ablation was 1382 ± 536 mGy.cm, while the CT fluoroscopic dose (DLP) per lesion was 352 ± 228 mGy.cm. There was no statistically significant (p > 0.05) dose reduction found between the robotic-assisted versus the conventional method.

CONCLUSION

This study revealed that robotic-assisted planning and needle placement appears to be safe, with high accuracy and a comparable radiation dose to patients.

KEY POINTS

• Clinical experience on liver thermal ablation using CT-guided robotic system is reported. • The technical success, radiation dose, safety and performance level were assessed. • Thermal ablations were successfully performed, with an average performance score of 4.4/5.0. • Robotic-assisted ablation can potentially increase capabilities of less skilled interventional radiologists. • Cost-effectiveness needs to be proven in further studies.

Torsional dynamics of steerable needles: modeling and fluoroscopic guidance

Needle insertions underlie a diversity of medical interventions. Steerable needles provide a means by which to enhance existing needle-based interventions and facilitate new ones. Tip-steerable needles follow a curved path and can be steered by twisting the needle base during insertion, but this twisting excites torsional dynamics that introduce a discrepancy between the base and tip twist angles. Here, we model the torsional dynamics of a flexible rod-such as a tip-steerable needle-during subsurface insertion and develop a new controller based on the model. The torsional model incorporates time-varying mode shapes to capture the changing boundary conditions inherent during insertion. Numerical simulations and physical experiments using two distinct setups-stereo camera feedback in semitransparent artificial tissue and feedback control with real-time X-ray imaging in optically opaque artificial tissue-demonstrate the need to account for torsional dynamics in control of the needle tip.

Use of a radiopaque localizer grid to reduce radiation exposure

Background

Minimally invasive spine surgery requires placement of the skin incision at an ideal location in the patient's back by the surgeon. However, numerous fluoroscopic x-ray images are sometimes required to find the site of entry, thereby exposing patients and Operating Room personnel to additional radiation. To minimize this exposure, a radiopaque localizer grid was devised to increase planning efficiency and reduce radiation exposure.

Results

The radiopaque localizer grid was utilized to plan the point of entry for minimally invasive spine surgery. Use of the grid allowed the surgeon to accurately pinpoint the ideal entry point for the procedure with just one or two fluoroscopic X-ray images.

Conclusions

The reusable localizer grid is a simple and practical device that may be utilized to more efficiently plan an entry site on the skin, thus reducing radiation exposure. This device or a modified version may be utilized for any procedure involving the spine.

Efficacy of CT-guided biopsies of the spine in patients with spondylitis--an analysis of 164 procedures

OBJECTIVE

To evaluate efficacy of CT-guided spinal biopsy (CTSB) in patients with spondylitis considering patient characteristics, technical issues, antibiotic therapy, histopathological, and microbiological findings.

MATERIALS AND METHODS

All CTSB procedures performed between 1995 and 2009 in patients with proven spondylitis were re-evaluated. Patient sex and age, antibiotic treatment, biopsy approach, number of specimens, length of needle path, laboratory results (CRP, WBC), and histopathological/microbiological findings were documented and compared to the final diagnosis of spondylitis. Statistical analysis was performed using Chi-square test and Student's t-test. The p-value was set to 5%.

RESULTS

164 CTSB procedures were performed in 159 patients (mean age 65 years, 60% men) in which spondylitis was histopathologically verified in 95%. Neither patient sex nor age, positioning, localization of the spinal lesion, bioptic approach, number of specimens, or depth of the needle showed significant impact on the rate of positive histopathological findings. A causative germ was identified in 40/127 biopsies (32%) with Staphylococcus aureus being identified in 50%. Tuberculous spondylitis was diagnosed in ten cases (6%). CRP significantly correlated with bacterial growth (13.3±12.2 mg/dl versus 8.8±7.6 mg/dl; p=.015) whereas administration of antibiotics did not show any significant impact on bacterial growth (29% versus 36% in patients without antibiotics; p=0.428). Patients with histopathological signs of active spondylitis showed a significantly higher CRP (16.5±15.8 mg/dl versus 8.9±8.0 mg/dl, p<.001). Complication rate was 0.6% (one focal bleeding).

CONCLUSION

CTSB of the spine in suspected spondylitis is an effective and safe procedure for establishing final histopathological diagnosis. However, microbiological yield is low regardless of technical issues and antibiotic therapy. Other than CRP values, laboratory investigations added little useful information to diagnose infection in our study group. CRP values significantly correlated with bacterial growth and with histopathological signs of active spondylitis.

Modified transcorporeal anterior cervical microforaminotomy assisted by O-arm-based navigation: a technical case report

This study was done to present our surgical experience of modified transcorporeal anterior cervical microforaminotomy (MTACM) assisted by the O-arm-based navigation system for the treatment of cervical disc herniation. We present eight patients with foraminal disc herniations at the C5-C6, C6-C7, and C7-T1 levels. All patients had unilateral radicular arm pain and motor weakness. The inclusion criteria for the patients were the presence of single-level unilateral foraminal cervical disc herniation manifesting persistent radiculopathy despite conservative treatment. Hard disc herniation, down-migrated disc herniation, concomitant moderate to severe bony spur and foraminal stenosis were excluded. We performed MTACM to expose the foraminal area of the cervical disc and removed the herniated disc fragments successfully using O-arm-based navigation. Postoperatively, the patients' symptoms improved and there was no instability during the follow-up period. MTACM assisted by O-arm-based navigation is an effective, safe, and precise minimally invasive procedure that tends to preserve non-degenerated structures as much as possible while providing a complete removal of ruptured disc fragments in the cervical spine.

Effectiveness of CT-guided percutaneous biopsies of the spine: an analysis of 202 examinations

RATIONALE AND OBJECTIVES

The study goal was to retrospectively evaluate the effectiveness of computed tomography (CT)-guided spinal biopsies.

MATERIAL AND METHODS

Two hundred two CT-guided vertebral biopsies performed between May 1999 and June 2004 in 187 patients were retrospectively analyzed. Patient characteristics (age, sex, antibiotic therapy), technical parameters (depth and number of biopsies, needle approach), lesion features (spinal level, osteolysis, fluid collections, soft tissue tumor), and complications were documented. Furthermore, histopathological and microbiological diagnoses were considered.

RESULTS

There were two focal hematomas in our study group (complication rate: 1%). Histopathological diagnosis was established in 74% of examinations with spondylitis (41% of cases) being most common. In spinal tumors (27% of cases), malignant lesions were found in 52 of 54 examinations (96%). Osteolysis was diagnosed in 98% of patients with spondylitis and in 87% of patients with tumors (P < .01). Spinal tumors were most commonly seen in the sacrum (53%, P < .001), whereas spondylitis typically occurred in the lumbar spine (55%, P = .001). Neither patient age nor sex, needle approach, needle depth, or vertebral abnormalities showed a significant impact on diagnostic accuracy. Microbiological tests were performed in 98 patients (49%); 62 of 98 patients (65%) received antibiotic therapy. In 12 of 62 patients (19%) with antibiotic therapy and in 9 of 36 patients (25%) without antibiotic treatment, microbiological tests were positive (P = .153). Staphylococcus aureus was found in 9 of 21 examinations (43%).

CONCLUSIONS

CT-guided vertebral biopsy is a safe and effective procedure to establish final diagnosis in spinal lesions of unclear origin. Patient characteristics, lesions features, and technical considerations did not influence sample quality. In spondylitis, which was commonly caused by Staphylococcus aureus, microbiological yield was low regardless of antibiotic therapy.

CT fluoroscopically guided percutaneous placement of transiliosacral rod for sacral insufficiency fracture: case report and technique

Treatment of sacral insufficiency fractures (SIFs) has traditionally been conservative, but several patients have been treated with percutaneous sacroplasty. Unfortunately, in the setting of severe, bilateral SIFs, cement may not withstand shear forces present at the lumbosacral junction, and surgical hardware may not provide adequate fixation in osteoporotic, cancellous bone of the sacrum, leading to eventual pseudarthrosis. Thus, we propose a novel technique in which guidance with CT fluoroscopy allows placement of a transiliosacral bar in conjunction with sacroplasty.

Distributed computing methodology for training neural networks in an image-guided diagnostic application

Distributed computing is a process through which a set of computers connected by a network is used collectively to solve a single problem. In this paper, we propose a distributed computing methodology for training neural networks for the detection of lesions in colonoscopy. Our approach is based on partitioning the training set across multiple processors using a parallel virtual machine. In this way, interconnected computers of varied architectures can be used for the distributed evaluation of the error function and gradient values, and, thus, training neural networks utilizing various learning methods. The proposed methodology has large granularity and low synchronization, and has been implemented and tested. Our results indicate that the parallel virtual machine implementation of the training algorithms developed leads to considerable speedup, especially when large network architectures and training sets are used.

Computerized tomography guided sacroplasty: a practical treatment for sacral insufficiency fracture: case report

STUDY DESIGN

Small case series projecting widespread therapeutic implications.

OBJECTIVE

To promote sacroplasty as a feasible treatment for sacral insufficiency fractures.

SUMMARY OF BACKGROUND DATA

Osteoporosis, a major cause of vertebral and sacral insufficiency fractures, is an increasingly serious problem in the elderly population. Painful sacral fractures often cause patients to be immobile, and at increased risk for comorbidities and osteoporosis progression. Currently, there is no therapy available for the treatment of these fractures. Vertebroplasty has evolved as a standard of care for treating fractures as a result of malignant and nonmalignant spinal pathology. Sacroplasty represents a reasonable adaptation of this interventional technique.

METHODS

Computerized tomography (CT) guidance was used to monitor percutaneous polymethylmethacrylate injection into sacral insufficiency fractures.

RESULTS

We report 2 cases of elderly patients with posttraumatic sacral insufficiency fractures, whose symptoms were completely relieved following CT-guided internal fixation by percutaneous polymethylmethacrylate injection.

CONCLUSION

Under CT guidance, sacroplasty is a safe, practical, and effective solution to this underdiagnosed problem, with potential for comorbidities resulting in prolonged, costly hospital admissions for the elderly.

Technology improvements for image-guided and minimally invasive spine procedures

This paper reports on technology developments aimed at improving the state of the art for image-guided minimally invasive spine procedures. Back pain is a major health problem with serious economic consequences. Minimally invasive procedures to treat back pain are rapidly growing in popularity due to improvements in technique and the substantially reduced trauma to the patient versus open spinal surgery. Image guidance is an enabling technology for minimally invasive procedures, but technical problems remain that may limit the wider applicability of these techniques. The paper begins with a discussion of low back pain and the potential shortcomings of open back surgery. The advantages of minimally invasive procedures are enumerated, followed by a list of technical problems that must be overcome to enable the more widespread dissemination of these techniques. The technical problems include improved intraoperative imaging, fusion of images from multiple modalities, the visualization of oblique paths, percutaneous spine tracking, mechanical instrument guidance, and software architectures for technology integration. Technical developments to address some of these problems are discussed next. The discussion includes intraoperative computerized tomography (CT) imaging, magnetic resonance imaging (MRI)/CT image registration, three-dimensional (3-D) visualization, optical localization, and robotics for percutaneous instrument placement. Finally, the paper concludes by presenting several representative clinical applications: biopsy, vertebroplasty, nerve and facet blocks, and shunt placement. The program presented here is a first step to developing the physician-assist systems of the future, which will incorporate visualization, tracking, and robotics to enable the precision placement and manipulation of instruments with minimal trauma to the patient.