Faculty Bibliography

PURPOSE/OBJECTIVE:To evaluate the feasibility of magnetic resonance imaging (MRI)-guided vertebroplasty at 1.5 Tesla using augmented reality image overlay navigation. MATERIALS AND METHODS/METHODS:Twenty-five unilateral vertebroplasties [5 of 25 (20%) thoracic, 20 of 25 (80%) lumbar] were prospectively planned in 5 human cadavers. A clinical 1.5-Teslan MRI system was used. An augmented reality image overlay navigation system and 3D Slicer visualization software were used for MRI display, planning, and needle navigation. Intermittent MRI was used to monitor placement of the MRI-compatible vertebroplasty needle. Cement injections (3 ml of polymethylmethacrylate) were performed outside the bore. The cement deposits were assessed on intermediate-weighted MR images. Outcome variables included type of vertebral body access, number of required intermittent MRI control steps, location of final needle tip position, cement deposit location, and vertebroplasty time. RESULTS:All planned procedures (25 of 25, 100%) were performed. Sixteen of 25 (64%) transpedicular and 9 of 25 (36%) parapedicular access routes were used. Six (range 3-9) MRI control steps were required for needle placement. No inadvertent punctures were visualized. Final needle tip position and cement location were adequate in all cases (25 of 25, 100%) with a target error of the final needle tip position of 6.1 ± 1.9 mm (range 0.3-8.7 mm) and a distance between the planned needle tip position and the center of the cement deposit of 4.3 mm (range 0.8-6.8 mm). Time requirement for one level was 16 (range 11-21) min. CONCLUSION/CONCLUSIONS:MRI-guided vertebroplasty using image overlay navigation is feasible allowing for accurate vertebral body access and cement deposition in cadaveric thoracic and lumbar vertebral bodies.

High-resolution multidetector computed tomography (MDCT) arthrography of the shoulder can diagnose internal derangement of the glenohumeral joints including abnormalities of the rotator cuff, glenoid labrum, and articular cartilage. Isotropic data sets and postprocessing techniques enable interactive three-dimensional image analysis that is capable of reducing artifacts for metal implants. In this article, we review the indications for MDCT arthrography of the shoulder, highlight techniques and important features of the MDCT acquisition, and review normal and abnormal MDCT arthrography appearances of the glenohumeral joint.

Hip arthroplasty has become the standard treatment for end-stage hip disease, allowing pain relief and restoration of mobility in large numbers of patients; however, pain after hip arthroplasty occurs in as many as 40% of cases, and despite improved longevity, all implants eventually fail with time. Owing to the increasing numbers of hip arthroplasty procedures performed, the demographic factors, and the metal-on-metal arthroplasty systems with their associated risk for the development of adverse local tissue reactions to metal products, there is a growing demand for an accurate diagnosis of symptoms related to hip arthroplasty implants and for a way to monitor patients at risk. Magnetic resonance (MR) imaging has evolved into a powerful diagnostic tool for the evaluation of hip arthroplasty implants. Optimized conventional pulse sequences and metal artifact reduction techniques afford improved depiction of bone, implant-tissue interfaces, and periprosthetic soft tissue for the diagnosis of arthroplasty-related complications. Strategies for MR imaging of hip arthroplasty implants are presented, as well as the imaging appearances of common causes of painful and dysfunctional hip arthroplasty systems, including stress reactions and fractures; bone resorption and aseptic loosening; polyethylene wear-induced synovitis and osteolysis; adverse local tissue reactions to metal products; infection; heterotopic ossification; tendinopathy; neuropathy; and periprosthetic neoplasms. A checklist is provided for systematic evaluation of MR images of hip arthroplasty implants. MR imaging with optimized conventional pulse sequences and metal artifact reduction techniques is a comprehensive imaging modality for the evaluation of the hip after arthroplasty, contributing important information for diagnosis, prognosis, risk stratification, and surgical planning.

BACKGROUND:Owing to the high risk of abscess drainage by craniotomy, imaging-guided stereotactic aspiration is considered an ideal choice in the management of brain abscesses. Interventional magnetic resonance imaging (MRI) represents a valuable technique for the treatment of brain abscess as a guiding modality. PURPOSE/OBJECTIVE:To evaluate the safety and efficacy of an interventional MRI system in performing the procedure. MATERIAL AND METHODS/METHODS:Thirteen brain abscesses in 11 patients were treated with percutaneous aspiration. All procedures were performed solely under the guidance of a 0.23-T open-configuration MRI scanner with optical tracking. Clinical and imaging follow-up was at 1 week, 1 month, 3 months, and 6 months. The changes of abscess, MRI features, and clinical symptoms were recorded. Procedure efficacy and safety were evaluated by success rate, procedure time, decrease of abscess, recovery rate, and complication. Descriptive statistical analysis was performed. RESULTS:MRI-guided stereotactic aspirations were performed successfully in 13/13 (100%) abscesses. The mean operating time was 70 min (range, 45-100 min). Follow-up MRI at 1 week after the procedure showed average reduction of abscesses by 60% (2.1/3.5). And the abscesses continued to get smaller by up to 89.7% (3.14/3.5) at 1-month follow-up. All cavities resolved at the end of the 6-month follow-up period. The recovery rate was 100% for fever, headache, vomiting, papilledema, meningismus, altered sensorium, 75% (3/4) for hemiparesis, and 83.3% (5/6) for epilepsy. There were no complications. CONCLUSION/CONCLUSIONS:Punctures of brain abscesses with subsequent aspiration can be performed safely and efficiently by monitoring the procedure using an open interventional MRI system.

Magnetic resonance (MR) neurography - guided nerve blocks and injections describe a techniques for selective percutaneous drug delivery, in which limited MR neurography and interventional MR imaging are used jointly to map and target specific pelvic nerves or muscles, navigate needles to the target, visualize the injected drug and detect spread to confounding structures. The procedures described, specifically include nerve blocks of the obturator nerve, lateral femoral cutaneous nerve, pudendal nerve, posterior femoral cutaneous nerve, sciatic nerve, ganglion impar, sacral spinal nerve, and injection into the piriformis muscle.

Imaging studies are central to the evaluation of persistent or recurrent symptoms after hip arthroplasty. The evaluation starts with radiographs and may be followed by arthrography, aspiration, scintigraphy, sonography, computed tomography, and MR imaging. Common etiologies of a painful or dysfunctional hip arthroplasty are mechanical loosening, polyethylene wear-induced osteolysis, adverse local tissue reaction to metal wear products, infection, fractures, heterotopic ossification, tendinopathy, and nerve injury. MR imaging with optimized protocols and dedicated techniques for metal artifact reduction is the most comprehensive imaging modality. In this article, we discuss and illustrate the imaging appearances of these conditions with a focus on the MR imaging evaluation.

PURPOSE/OBJECTIVE:To assess the performance of sterile saline solution as the sole contrast agent for percutaneous magnetic resonance imaging (MRI)-guided epidural injections at 1.5 T. METHODS:A retrospective analysis of two different techniques of MRI-guided epidural injections was performed with either gadolinium-enhanced saline solution or sterile saline solution for documentation of the epidural location of the needle tip. T1-weighted spoiled gradient echo (FLASH) images or T2-weighted single-shot turbo spin echo (HASTE) images visualized the test injectants. Methods were compared by technical success rate, image quality, table time, and rate of complications. RESULTS:105 MRI-guided epidural injections (12 of 105 with gadolinium-enhanced saline solution and 93 of 105 with sterile saline solution) were performed successfully and without complications. Visualization of sterile saline solution and gadolinium-enhanced saline solution was sufficient, good, or excellent in all 105 interventions. For either test injectant, quantitative image analysis demonstrated comparable high contrast-to-noise ratios of test injectants to adjacent body substances with reliable statistical significance levels (p < 0.001). The mean table time was 22 ± 9 min in the gadolinium-enhanced saline solution group and 22 ± 8 min in the saline solution group (p = 0.75). CONCLUSION/CONCLUSIONS:Sterile saline is suitable as the sole contrast agent for successful and safe percutaneous MRI-guided epidural drug delivery at 1.5 T.

Multi-detector computed tomography angiography (MDCTA) of the lower extremities is an integral part of the decision-making process of lower extremity trauma. MDCTA can be integrated into multiphasic whole-body trauma MDCT and has replaced the traditional gold standard of catheter-based angiography as the preferred technique for the initial assessment of lower extremity trauma in many institutions worldwide. Advances in MDCT technology enable high speed simultaneous evaluation of both complete lower extremities, rapid image reconstruction, and advanced image visualization for the noninvasive and accurate diagnosis of vascular, including hematoma, active extravasation, vasospasm, stenosis, external compression, occlusion, intimal injury and dissection, arteriovenous fistulas, and pseudoaneurysm formation. In this exhibit, we outline the role of MDCTA in the management of lower extremity trauma, review current MDCT protocols and the practical use of advanced visualization techniques, and illustrate typical MDCTA findings, pearls, and pitfalls, which help to accurately characterize vascular injury and guide management.

OBJECTIVE:The objective of this study was to evaluate the diagnostic performance and safety of magnetic resonance (MR) imaging-guided percutaneous mediastinal biopsy procedures using a 0.23-T open MR system with optical tracking navigation. MATERIALS AND METHODS/METHODS:A retrospective analysis of 59 participants (38 males and 21 females; mean age, 45 years; range, 16-73 years) who underwent MR imaging-guided percutaneous mediastinal biopsy procedures was performed. The access techniques included extrapleural (40 of 59; 67.8%) and transpulmonary (19 of 59; 32.2%) needle paths. Tissue sampling techniques included fine-needle aspiration (22 of 59; 37.3%) and core-needle biopsy (37 of 59; 62.7%). Histopathological analysis of surgical specimen and clinical and imaging follow-ups were used as the reference standard. The procedures were evaluated for technical success rate, number of biopsy passes, diagnostic performance, procedure time, and complications. RESULTS:Technical success was achieved in 57 of the 59 procedures (96.6%). For the fine-needle aspiration, a mean of 3 passes (range, 2-4 passes) was performed. For the core-needle biopsy, a mean of 4 passes (range, 3-6 passes) was performed. Pathological and cytological analysis of biopsy specimens showed 41 of 57 malignant lesions (71.9%) and 16 of 57 benign lesions (28.1%), with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 93.2% (41 of 44), 100% (13 of 13), 100% (41 of 41), 81.2% (13 of 16), and 94.7% (54 of 57), respectively. Procedure time was 30 minutes (range, 20-50 minutes). Mild hemoptysis occurred in 3 cases, and in 2 cases, a small pneumothorax occurred. CONCLUSIONS:Magnetic resonance imaging-guided biopsy of mediastinal masses has a high diagnostic performance and is safe for use in clinical practice.

PURPOSE/OBJECTIVE:The purpose of this study was to prospectively test the hypothesis that image overlay technology facilitates accurate navigation for magnetic resonance (MR)-guided osseous biopsy. MATERIALS AND METHODS/METHODS:A prototype augmented reality image overlay system was used in conjunction with a clinical 1.5-T MR imaging system. Osseous biopsy of a total of 16 lesions was planned in 4 human cadavers with osseous metastases. A loadable module of 3D Slicer open-source medical image analysis and visualization software was developed and used for display of MR images, lesion identification, planning of virtual biopsy paths, and navigation of drill placement. The osseous drill biopsy was performed by maneuvering the drill along the displayed MR image containing the virtual biopsy path into the target. The drill placement and the final drill position were monitored by intermittent MR imaging. Outcome variables included successful drill placement, number of intermittent MR imaging control steps, target error, number of performed passes and tissue sampling, time requirements, and pathological analysis of the obtained osseous core specimens including adequacy of specimens, presence of tumor cells, and degree of necrosis. RESULTS:A total of 16 osseous lesions were sampled with percutaneous osseous drill biopsy. Eight lesions were located in the osseous pelvis (8/16, 50%) and 8 (8/16, 50%) lesions were located in the thoracic and lumbar spine. Lesion size was 2.2 cm (1.1-3.5 cm). Four (2-8) MR imaging control steps were required. MR imaging demonstrated successful drill placement inside 16 of the 16 target lesions (100%). One needle pass was sufficient for accurate targeting of all lesions. One tissue sample was obtained in 8 of the 16 lesions (50%); 2, in 6 of the 16 lesions (38%); and 3, in 2 of the 16 lesions (12%). The target error was 4.3 mm (0.8-6.8 mm). Length of time required for biopsy of a single lesion was 38 minutes (20-55 minutes). Specimens of 15 of the 16 lesions (94%) were sufficient for pathological evaluation. Of those 15 diagnostic specimens, 14 (93%) contained neoplastic cells, whereas 1 (7%) specimen demonstrated bone marrow without evidence of neoplastic cells. Of those 14 diagnostic specimens, 11 (79%) were diagnostic for carcinoma or adenocarcinoma, which was concordant with the primary neoplasm, whereas, in 3 of the 14 diagnostic specimens (21%), the neoplastic cells were indeterminate. CONCLUSIONS:Image overlay technology provided accurate navigation for the MR-guided biopsy of osseous lesions of the spine and the pelvis in human cadavers at 1.5 T. The high technical and diagnostic yield supports further evaluation with clinical trials.