Post-vertebral augmentation spine imaging.

Although imaging plays a critical role and has become an integral part in preprocedure evaluation of osteoporotic patients at risk of compression fracture, many treated patients undergo follow-up imaging, for reasons ranging from potential procedure-related complications to development of new symptoms after initial improvement after successful vertebral augmentation (VA). Although imaging is frequently obtained for evaluation of these patients, there is a general lack of knowledge about imaging characteristics of treated vertebrae. This article reviews various indications for post-VA imaging, the appearance of augmented spine on imaging, and the important complications associated with the VA procedure.

MR-guided vertebroplasty with augmented reality image overlay navigation.

PURPOSE: To evaluate the feasibility of magnetic resonance imaging (MRI)-guided vertebroplasty at 1.5 Tesla using augmented reality image overlay navigation. MATERIALS AND 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: 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 magnetic resonance-guided posterior femoral cutaneous nerve blocks.

OBJECTIVE: To assess the feasibility, technical success, and effectiveness of high-resolution magnetic resonance (MR)-guided posterior femoral cutaneous nerve (PFCN) blocks. MATERIALS AND METHODS: A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 patients [6 (75%) female, 2 (25%) male; mean age, 47 years; range, 42-84 years] with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed with a clinical wide-bore 1.5-T MR imaging system. High-resolution MR imaging was utilized for visualization and targeting of the PFCN. Commercially available, MR-compatible 20-G needles were used for drug delivery. Variables assessed were technical success (defined as injectant surrounding the targeted PFCN on post-intervention MR images) effectiveness, (defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block), rate of complications, and length of procedure time. RESULTS: MR-guided PFCN injections were technically successful in 12/12 cases (100%) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100%). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30-70) min. CONCLUSIONS: Our initial results demonstrate that this technique of selective MR-guided PFCN blocks is feasible and suggest high technical success and effectiveness. Larger studies are needed to confirm our initial results.

Percutaneous plasma mediated radiofrequency ablation of spinal osteoid osteomas.

Plasma mediated radiofrequency ablation (pmRFA) may allow for the percutaneous treatment of spinal tumors with a decreased risk of thermal injury to neural structures compared with traditional (radiofrequency or interstitial laser) ablation. However, usage of pmRFA has not been previously reported for a primary bone tumor, including an osteoid osteoma. Three patients with a spinal osteoid osteoma underwent pmRFA. The procedure was performed under computed tomography guidance using the 11 gauge Coblation SpineWand (ArthroCare). One lesion (at T11) was directly abutting the spinal canal. With an average follow-up of 20.7 (range 16-24) months, the mean Visual Analog Scale score for back pain decreased from 8.67 to 0.67 and no patient experienced tumor recurrence. pmRFA of spinal osteoid osteomas is feasible, even when the tumor is abutting the spinal canal. Larger studies with a longer follow-up are needed to further delineate the safety and efficacy of this technique.

Undulating microcatheter tip motion with respiratory cycle during intracranial aneurysm embolization: description of a case and strategy for its mitigation.

The present report describes a technique for mitigating respiration-related microcatheter motion during endovascular aneurysm treatment by modulating ventilator settings. A rare phenomenon of microcatheter tip movement related to respiration is demonstrated. An adjustment of tidal volume and respiratory rate reduced the degree of inspiratory vessel elongation and stabilized the microcatheter position, allowing for safer, more precise coil deployment. This maneuver can easily be applied to other endovascular procedures for which aberrant microcatheter motion must be minimized.

Congenital arterial and venous anomalies of the brain and skull base.

Congenital cerebral vascular anomalies include a spectrum of conditions that result from perturbation of normal developmental processes. Although some of these conditions are asymptomatic and well compensated by collateral circulation, others can cause significant morbidity or produce a range of complications for affected patients. Knowledge of the underlying developmental etiologies and the associated imaging characteristics helps fully elucidate the morphologic and hemodynamic details of these lesions and determine the necessity for any intervention.

Normal cerebral arterial development and variations.

The cerebral vascular architecture is both unique and heterogeneous in its structure, organization, and function. For many years, it was believed that brain vasculature was dominated by nonanastomosing terminal or "end-arteries." This was primarily based upon the observation of discrete distribution of brain infarcts after embolic occlusion of particular vessels. It was not until the detailed anatomy work of Pfeiffer in 1928 that the new concept of an almost-uninterrupted vascular network of brain vasculature was proposed. Since then, the cerebral vascular anatomy and embryology has been studied in great detail. Its full description is beyond the scope of this article, and our aim is to provide a brief overview of the development of cranial arterial anatomy, with special emphasis on commonly encountered anatomical variations that may have clinical implications. The failure to recognize these can lead to misdiagnosis as well as otherwise-preventable iatrogenic injuries and complications. We describe the proposed underlying embryologic processes, pathology and clinical implications of these variations, including aberrant internal carotid arteries, carotid agenesis and hypoplasia, azygous anterior cerebral arteries, arterial fenestrations, and persistent embryonic vessels.

Improved diagnosis of actively bleeding aneurysm on CT angiography using delayed CT images.

Computed tomographic angiography (CTA) is being increasingly utilized in the non-invasive diagnosis of aneurysmal subarachnoid hemorrhage (SAH). There are emerging reports of diagnosis of active aneurysmal bleeding on CTA, furthering our understanding of imaging features of active extravasation on cross-sectional studies. We demonstrate imaging characteristics of two such cases of active contrast extravasation from intracranial aneurysms. Additionally, we demonstrate that delayed CT images greatly improve the confidence of this diagnosis by demonstrating pooling of contrast in the subarachnoid space. Prompt recognition and management can improve prognosis of this potentially lethal condition.

Successful treatment of a symptomatic L5/S1 discal cyst by percutaneous CT-guided aspiration.

BACKGROUND: Discal cysts are a rare cause of lumbar radiculopathy. Benefits of percutaneous computed tomography (CT)-guided aspiration of the cyst include decreased rate of infection, avoidance of general anesthesia, and quicker recovery. However, since the publication of a case of cyst recurrence after CT-guided aspiration, few have utilized this potentially valuable technique. CASE DESCRIPTION: We present a patient with a discal cyst arising from the L5/S1 disc causing right S1 radiculopathy. He underwent percutaneous CT-guided aspiration with substantial improvement in his radicular pain with 19 months of follow-up. His improvement was measured quantitatively using the Japanese Orthopedic Association scale: 6/15 pre-procedure, 15/15 post-procedure. CONCLUSION: Percutaneous CT-guided aspiration of discal cysts may be a valid initial treatment option for this condition. Patients who do not respond or who have a recurrence can subsequently be treated by surgical excision.

Noninvasive imaging techniques in the diagnosis and management of aneurysmal subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating condition, requiring prompt diagnosis and therapeutic intervention as well as close monitoring for the development of complications including vasospasm (VS). Although digital subtraction angiography is still considered the gold standard for the diagnosis of aSAH (and vasospasm), new and less invasive modalities are emerging including ultrasound, CT, CT angiography and CT perfusion, and MR imaging. The current evidence for the use of these newer modalities is described for the diagnosis of aSAH and the management of its sequelae including VS.

State of the art head and neck imaging for the endovascular specialist.

Recent technologic advances including multidetector CT, dynamic CT angiography, high-field MR imaging, four-dimensional MR angiography, and physiologic studies, such as perfusion imaging, have revolutionized the imaging work-up of head, neck, and skull base lesions. These techniques not only provide accurate diagnostic information, but also help plan endovascular therapy. The future holds great promise for interventional neuroradiologists because excellent imaging tools are becoming available that are capable of providing morphologic, hemodynamic, and physiologic information. Furthermore, availability of faster, real-time guidance systems and hybrid systems improves the ability to perform procedures not only in a rapid and safe manner but also with great precision.