MR Angiography of the Spine and Spinal Cord

Imaging protocols for non-traumatic spinal cord injury: current state of the art and future directions

INTRODUCTION

Non-traumatic spinal cord injury (NTSCI) is a term used to describe damage to the spinal cord from sources other than trauma. Neuroimaging techniques such as computerized tomography (CT) and magnetic resonance imaging (MRI) have improved our ability to diagnose and manage NTSCIs. Several practice guidelines utilize MRI in the diagnostic evaluation of traumatic and non-traumatic SCI to direct surgical intervention.

AREAS COVERED

The authors review practices surrounding the imaging of various causes of NTSCI as well as recent advances and future directions for the use of novel imaging modalities in this realm. The authors also present discussions around the use of simple radiographs and advanced MRI modalities in clinical settings, and briefly highlight areas of active research that seek to advance our understanding and improve patient care.

EXPERT OPINION

Although several obstacles must be overcome, it appears highly likely that novel quantitative imaging features and advancements in artificial intelligence (AI) as well as machine learning (ML) will revolutionize degenerative cervical myelopathy (DCM) care by providing earlier diagnosis, accurate localization, monitoring for deterioration and neurological recovery, outcome prediction, and standardized practice. Some intriguing findings in these areas have been published, including the identification of possible serum and cerebrospinal fluid biomarkers, which are currently in the early phases of translation.

3D visualization and morphometric analysis of spinal motion segments and vascular networks: A synchrotron radiation-based micro-CT study in mice

The structure of spinal motion segments and spinal vasculature is complicated. Visualizing the three-dimensional (3D) structure of the spine may provide guidance for spine surgery. However, conventional imaging techniques fail to simultaneously obtain 3D images of soft and hard tissues, and achieving such coimaging states of the spine and its vascular networks remains a challenge. Synchrotron radiation micro-CT (SRμCT) provides a relatively effective and novel method of acquiring detailed 3D information. In this study, specimens of the thoracic spine were obtained from six mice. SRμCT was employed to acquire 3D images of the structure, and histologic staining was performed for comparisons with the SRμCT images. The whole spinal motion segments and the spinal vascular network were simultaneously explored at high resolution. The mean thickness of the cartilaginous end plates (CEPs) and the volume of the intervertebral discs (IVDs) were calculated. The surface of the CEPs and the facet joint cartilage (FJC) were presented as heat maps, which allowed for direct visualization of the thickness distribution. Regional division revealed heterogeneity among the ventral, central, and dorsal parts of the CEPs and between the superior and inferior parts of the facet processes. Moreover, the connections and spatial morphology of the spinal vascular network were visualized. Our study indicates that SRμCT imaging is an ideal method for high-resolution visualization and 3D morphometric analysis of the whole spinal motion segments and spinal vascular network.

Imaging Considerations in Spinal Cord Evaluation

Multiple diverse pathologies result in the clinical presentation of myelopathy. The preferred way to image the spinal cord depends on clinical history, anatomic site of interest, and patient issues limiting certain imaging modalities. This radiology-focused article discusses pertinent physiological considerations, reviews basic and newer imaging techniques, and examines several distinct disease entities in order to highlight the key role of imaging in the work-up of myelopathy.

Spinal dural fistula evaluation using 4-Dimensional intra-aortic spinal CTAngiography in a hybrid angiography suite

Intra-aortic CT Angiography (IA-CTA) is a relatively new technique that shows promise in efficient diagnosis and evaluation of the angioarchitecture of spinal dural arteriovenous fistulae(sdAVF). The authors document the first reported use of a 4D-CT and C-arm fluoroscope in a hybrid interventional suite to evaluate a sdAVF. Time resolved IA-CTA is clinically feasible in the evaluation of sdAVF, has higher temporal resolution as compared to standard IA-CTA and reduced contrast load, radiation dose and potential for procedural complications as compared to standard spinal angiography.

Vascular imaging of the spine in the US Medicare population: Catheter and MR angiography volumes from 2004 to 2016

AIMS

The purpose of our study was to analyze utilization trends and physician specialty distribution in spinal catheter angiography and magnetic resonance angiography in the Medicare fee-for-service population.

METHODS

Data from the CMS Physician/Supplier Procedure Summary Master Files for 2004 to 2016 were used for this study. The Current Procedural Terminology version 4 codes for spinal magnetic resonance angiography (72159) and spinal catheter angiography (75705) were used to analyze the volumes of these procedures. Using Medicare's 108 specialty code, we compared procedure volumes among physician specialties. Data analysis was performed using SAS version 9.3 for Windows.

RESULTS

The volume of spinal catheter angiography performed was 4758 in 2004, peaked at 6869 in 2012, and dropped to 6656 in 2016. Overall, the volume of spinal catheter angiography increased by 40% from 2004 to 2016. Radiologists performed the majority of these procedures (3736 or 56.1%) in 2016, followed by neurosurgeons (2456 or 36.9%), and neurologists (346 or 5.2%). The spinal magnetic resonance angiography volume fluctuated between 0 and 1 from 2004 to 2009, then precipitously increased to 40 in 2010, peaked at 133 in 2011, and declined to 81 in 2016. The volume of spinal magnetic resonance angiography procedures increased by 8000% from 2004 to 2016, with radiologists performing the majority of them.

CONCLUSION

Our results show that spinal catheter angiography volumes continue to rise in the Medicare fee-for-service population, and are largely performed by radiologists, neurosurgeons, and neurologists. Although spinal magnetic resonance angiography volumes have started to increase, they comprise only a small fraction of studies performed for vascular evaluation of the spine.

Microsurgical Management of a Spinal Dural Arteriovenous Fistula With Shared Blood Supply to the Artery of Adamkiewicz: 3-Dimensional Operative Video

The presented case is of a 65-yr-old gentleman referred for thoracic myelopathy. He developed bilateral, nondermatomal foot dysesthesia 14 mo prior to presentation, which progressed to numbness below the L3 level. He reported progressive gait instability, bilateral lower extremity weakness, and required a cane for ambulation. He subsequently developed urinary incontinence, while bowel function was spared. The neurological examination upon presentation revealed lower extremity strength was reduced to 4/5 in all major muscle groups bilaterally, while sensation and proprioception were reduced below the L3 level. Patellar and Achilles reflexes were not elicited and clonus was absent. Gait was unsteady and slow. The patient was not able to perform heel, toe and tandem gait. MRI revealed abnormal T2 hyper-intense signal and spinal cord expansion from T6 through the conus medullaris. Angiography revealed a dural arteriovenous fistula (dAVF) originating from the left T9 radicomedullary pedicle, which also supplied the Artery of Adamkiewicz (AoA). The patient underwent T8-10 laminectomies. Prior to disconnection of the fistula, an aneurysm clip was applied to the fistulous point and an indocyanine green video angiogram was completed to show that the fistula no longer opacified, but that the AoA remained patent, which was later confirmed with angiography. As of discharge, the patient's motor exam had improved substantially, though his sensory deficits persisted. This case demonstrates that surgical disconnection is requisite in the treatment of spinal dAVF that have a shared blood supply with the AoA, as embolization risks spinal cord infarction.  The patient consented to presentation of this case in a de-identified fashion.

ACR Appropriateness Criteria® Ataxia

Ataxia can result from an abnormality in the cerebellum, spinal cord, peripheral nerves, and/or vestibular system. Pathology involving the brain, such as infarct or hydrocephalus, can also present with ataxia as part of the symptom constitution, or result in symptoms that mimic ataxia. Clinical evaluation by history and careful neurological examination is important to help with lesion localization, and helps determine where imaging should be focused. In the setting of trauma with the area of suspicion in the brain, a head CT without intravenous contrast is the preferred initial imaging choice. If vascular injury is suspected, CTA of the neck can be helpful. When the area of suspicion is in the spine, CT or MRI of the spine can be considered to assess for bony or soft-tissue injury, respectively. In the setting of ataxia unrelated to recent trauma, MRI is the preferred imaging modality, tailored to assess the brain or spine depending on the area of suspected pathology. The use of intravenous contrast is generally helpful. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The Initial Exploration of Adamkiewicz Artery Computed Tomographic Angiography With Monochromatic Reconstruction of Gemstone Spectral Imaging

OBJECTIVE

The study aimed to explore whether optimal monochromatic reconstruction can improve the depiction of the Adamkiewicz artery (AKA) on gemstone spectral computed tomographic angiography (GSCTA) compared with the polychromatic reconstruction protocol.

METHODS

The prospective study was approved by the ethics committee, and written informed consent was obtained from each patient. The 58 consecutive patients suspected of aortic aneurysm or dissection underwent aortic GSCTA. All images were reconstructed with both polychromatic (group A) and optimal monochromatic (group B) protocol. The CT values of the descending aorta and muscle, background noise, and the contrast-to-noise ratio were measured and calculated. With the criterion standard display of AKA, characteristic hairpin curve sign, 2 blinded radiologists analyzed data independently with the paired samples t, χ, and Mann-Whitney U test.

RESULTS

The CT value of the descending aorta and the contrast-to-noise ratio of group B were significantly superior to group A (t = 12.7, P < 0.01; t = 15.2, P < 0.01). The visual rate of AKA (94.8%) in group B was significantly higher (χ = 4.2, P = 0.04) than group A (82.8%). Using a 5-point scale to assess, the score of the visualization efficiency of group B (226) was significantly higher (Z = -2.4, P = 0.02) than group A (192).

CONCLUSIONS

The optimal monochromatic reconstruction for GSCTA can improve the visualization efficiency and quality of the AKA compared with the polychromatic reconstruction protocol.

Spinal arteriovenous shunts: accuracy of shunt detection, localization, and subtype discrimination using spinal magnetic resonance angiography and manual contrast injection using a syringe

OBJECT

The object of this study was to evaluate the accuracy of fast 3D contrast-enhanced spinal MR angiography (MRA) using a manual syringe contrast injection technique for detecting and evaluating spinal arteriovenous shunts (AVSs).

METHODS

This was a retrospective study of 15 patients and 20 spinal MRA and catheter angiography studies. The accuracy of using spinal MRA to detect spinal AVS, localize shunts, and discriminate the subtype and dominant arterial feeder of the AVS were studied.

RESULTS

There were 14 pretherapeutic and 6 posttherapeutic follow-up spinal MRA and catheter spinal angiography studies. The spinal AVS was demonstrated in 17 of 20 studies. Spinal MRA demonstrated 100% sensitivity for detecting spinal AVS with no false-negative results. A 97% accuracy rate for AVS subtype discrimination and shunt level localization was achieved using this study's diagnostic criteria. The detection of the dominant arterial feeder was limited to 9 of these 17 cases (53%).

CONCLUSIONS

The fast 3D contrast-enhanced MRA technique performed using manual syringe contrast injection can detect the presence of a spinal AVS, locate the shunt level, and discriminate AVS subtype in most cases, but is limited when detecting small arterial feeders.

Spinal Cervical Meningiomas: The Challenge Posed by Ventral Location

OBJECTIVE

To evaluate the incidence, clinical presentation, operative techniques, and long-term outcome of spinal cervical meningiomas after surgery.

METHODS

Twenty-two patients harboring spinal meningiomas on cervical region were treated between 2004 and 2014 in our department. Diagnosis was made via magnetic resonance imaging and confirmed histologically. Microsurgical resection was performed through different surgical approaches according to location of the tumor. To remove the tumor, the posterior, far-lateral, and combined approaches were used, respectively, in 13 patients (56%), 8 patients (35%), and 2 patients (9%).

RESULTS

The mean follow-up was 40 ± 26.5 months. The most common site of dural attachment of meningioma was ventral or ventrolateral to the spinal cord. Macroscopic resection was considered complete in 55% of cases. Neurologic improvement was observed in 60% of cases. The rate of operative mortality and morbidity was high (26.5%). Five patients underwent postoperative radiotherapy according to the actual recommendation, and the overall recurrence rate was 9%.

CONCLUSIONS

Spinal meningiomas are benign tumors for which advances in imaging tools and microsurgical techniques have yielded better results. The goal of surgery should be the total resection, which significantly decreases the risk of recurrence with an acceptable morbidity. Cervical locations represent a challenge particularly for ventro and ventrolaterally located tumors. Despite the difficulty of performing a complete resection, the results obtained in this work advocate for the use of the far-lateral approach to manage meningiomas locate anterior to the neural axis.

Imaging diagnosis and the role of endovascular embolization treatment for vascular intraspinal tumors

Intraspinal tumors comprise a large spectrum of neoplasms, including hemangioblastomas, paragangliomas, and meningiomas. These tumors have several common characteristic imaging features, such as highly vascular mass appearance in angiography, hypointense rim and serpentine flow voids in MRI, and intense enhancement after intravenous contrast administration. Due to their rich vascularity, these tumors represent a special challenge for surgical treatment. More recently, the surgical treatment of intraspinal vascular tumors has benefited from the combination of endovascular techniques used to better delineate these lesions and to promote preoperative reduction of volume and tissue blood flow. Endovascular embolization has been proven to be a safe procedure that facilitates the resection of these tumors; hence, it has been proposed as part of the standard of care in their management.

Clinical application and diagnostic value of noninvasive spinal angiography in spinal vascular malformations

OBJECTIVE

The purpose of this study was to explore the value of computed tomographic (CT) spinal angiography with 256-slice CT and fast dynamic contrast-enhanced 3-dimensional magnetic resonance angiography (MRA) at 3.0 T in the diagnosis of spinal vascular malformations.

METHODS

Seventeen patients who presented with suspected spinal vascular diseases by initial magnetic resonance and clinical findings all underwent CT spinal angiography. Among these, 10 patients underwent MRA, 15 patients underwent digital subtraction angiography (DSA) within 3 to 5 days, and 8 patients finally underwent surgical treatment.

RESULTS

Computed tomographic angiography examination clearly showed the abnormal vascular lesions in 16 of the 17 patients, including 7 patients with the diagnosis of spinal dural arteriovenous fistula, 7 patients with perimedullary arteriovenous fistula, and 2 patients with spinal arteriovenous malformations. The results were consistent with the diagnosis of DSA or surgery. One patient was poorly diagnosed. The fistulas could be seen in 12 patients; feeding arteries were correctly displayed in 12 patients. The fistulas and feeding arteries were accurately shown in 7 of 10 patients by MRA; DSA results were also negative in the other 3 patients.

CONCLUSIONS

Spinal angiography with 256-slice CT and contrast-enhanced MRA at 3.0 T can clearly show the extent of spinal vascular malformations, feeding arteries, and fistulas. They are safe, noninvasive, as well as rapid and can shorten the time of DSA diagnosis and treatment.

MRI and MRA of spinal cord arteriovenous shunts

The purpose of this review is to describe the diagnostic criteria for spinal cord arteriovenous shunts (SCAVSs) when using magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), and to discuss the extent to which the different MRI and MRA sequences and technical parameters provide the information that is required to diagnose these lesions properly. SCAVSs are divided into four groups according to location (paraspinal, epidural, dural, or intradural) and type (fistula or nidus); each type of lesion is described. SCAVSs are responsible for neurological symptoms due to spinal cord or nerve root involvement. MRI is usually the first examination performed when a spinal cord lesion is suspected. Recognition of the image characteristics of vascular lesions is mandatory if useful sequences are to be performed-especially MRA sequences. Because the treatment of SCAVSs relies mainly on endovascular therapies, MRI and MRA help with the planning of the angiographic procedure. We explain the choice of MRA sequences and parameters, the advantages and pitfalls to be aware of in order to obtain the best visualization, and the analysis of each lesion.

Common origin of the artery of adamkiewicz and a posterior spinal artery with a spinal dural arteriovenous fistula: a case report

Progressive nature of the myelopathy seen in patients with dural arteriovenous fistulas call for timely diagnosis and surgical intervention to alleviate symptoms of neurologic dysfunction. We present a case report of a 51-year-old male presented with progressive sensory and motor deficits, along with gait instability associated with urinary incontinence for a period of one year. MRI of the spine demonstrated a thoracic spinal dural arteriovenous fistula. Spinal angiography showed at T7 on the left a common origin of the artery of adamkiewicz, a posterior spinal artery and the spinal dural arteriovenous fistula. The fistula was surgically treated and the patient made an almost complete recovery. To the author's knowledge, this is the first time that this common origin, of the three vessels, is described in the literature.

Advances in imaging of the spinal cord vascular supply and its relationship with paraplegia after aortic interventions. A review

INTRODUCTION

Preoperative knowledge of the spinal cord (SC) vasculature could be useful for stratifying and decreasing the risk of perioperative paraplegia after thoracic and thoraco-abdominal aortic surgery. Recent advances in magnetic resonance (MR) and computed tomography (CT) angiography and post-processing techniques have improved this knowledge.

METHODS

A search of MEDLINE/Pubmed and SCOPUS databases identified 1414 pertinent abstracts; 123 full-length manuscripts were screened to identify relevant studies with acceptable design and patient numbers. Forty-three were selected.

RESULTS

SC circulation was studied in 1196 patients to detect the great radicular artery: 522 by MR-angiography and 674 by CT angiography. Detection rates were 67-100% (mean 80.8%) with MR-angiography being 18-100% (mean 72%) with CT angiography. The side and level of the great radicular artery were consistent between the methods. Several authors tried to use the imaging results to guide clinical management.

CONCLUSIONS

Non-invasive imaging of the SC blood supply allows preoperative definition of the vasculature in many, but not all, cases. The impact of these findings on clinical management is potentially beneficial but still uncertain. Further improvements in image acquisition and post-processing techniques are needed. Future studies need to be large enough to compensate for inter-individual variability in SC vasculature in health and disease; however, even a partial reduction of paraplegia rate offers a formidable motivation for further research in this area.

Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen's kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.

Optimal contrast medium injection protocols for the depiction of the Adamkiewicz artery using 64-detector CT angiography

AIM

To determine the optimal contrast medium injection protocol for demonstrating the Adamkiewicz artery (AKA) using 64-detector CT angiography (CTA).

MATERIALS AND METHODS

CTA was performed using 64-detector CT. The study population consisted of 80 patients (mean age 67.2 years) with aortoiliac diseases. In the first 60 patients 540 mg I/kg body weight was administered over 25s. The patients were randomly assigned to three protocols with imaging started at 15 (protocol A-1), 18 (A-2), or 21s (A-3) after triggering (threshold 150 HU). The other 20 received 720 mg I/kg body weight with an imaging delay of 18s (protocol B). Two radiologists evaluated the presence of the AKA and measured the attenuation of the aorta and AKA.

RESULTS

Aortic enhancement was 360.4, 348, 279.3, and 372 HU for protocols A-1, A-2, A-3, and B, respectively. There was no significant difference between the A-1 and A-2 protocols (Tukey-Kramer test, p=0.73); however, aortic enhancement was significantly lower in A-3 than A-1 and A-2 (p<0.01). There was no significant difference between A-2 and B (p=0.40). AKA attenuation was 69.3, 91.9, 94.6, and 105.4 HU for protocols A-1, A-2, A-3, and B, respectively. There was no significant difference between the A-2 and A-3 protocols (p=0.91); however, AKA attenuation was significantly lower with A-1 than A-2 or A-3 (p=0.01). AKA attenuation was significantly lower with A-2 than B (p=0.03) and there was a significant difference between A-2 (50%) and B (95%) in the depiction of the hairpin configuration of the AKA (p=0.02).

CONCLUSION

For the demonstration of the AKA at CTA, the optimal protocol used an imaging delay of 18s after triggering and an iodine dose of 720 mg I/kg body weight.

Advances in spinal cord MR angiography

Novel developments in MR angiography are reviewed that enable non-invasive clinical imaging of normal and abnormal vessels of the spinal cord. Current fast contrast-enhanced MR techniques are able 1) to visualize vessels supplying or draining the spinal cord and 2) to differentiate spinal cord arteries from veins. The localization of the Adamkiewicz artery, the largest artery supplying the thoracolumbar spinal cord, has become possible in a reproducible and reliable manner. Knowledge of the anatomic location of this artery and its arterial supplier may be of benefit in the work-up for aortic aneurysm surgery to reduce incidences of ischemic injury. Spinal cord MR angiography is ready to become a diagnostic tool that can compete with catheter angiography for detecting and localizing arterial feeders of vascular lesions and is strongly advised for use prior to invasive catheter angiography. Successful clinical application strongly relies on in depth knowledge of the complex spinal cord vasculature and skills in image postprocessing.

Value and limitations of contrast-enhanced MR angiography in spinal arteriovenous malformations and dural arteriovenous fistulas

BACKGROUND AND PURPOSE

The purpose of this work was to study the validity of MR angiography (MRA) for identification of spinal arteriovenous (AV) abnormalities.

MATERIALS AND METHODS

Thirty-four consecutive patients with suspicion of spinal vascular abnormalities underwent digital subtraction angiography (DSA) after MRA. The level and side of the suspected spinal dural arteriovenous fistula (SDAVF) and the feeding arteries in spinal arteriovenous malformations (SAVMs) were determined from the MRA and compared with DSA.

RESULTS

DSA revealed SDAVF in 20 abnormalities of which 19 were spinal and 1 was tentorial with spinal drainage, as well as SAVM in 11 patients. In 3 patients, MRA and DSA were both normal. For detection of spinal arteriovenous abnormalities, neither false-positive nor false-negative MRA results were obtained. The MRA-derived level of the feeding artery in SDAVF agreed with DSA in 14 of 19 cases. In 5 cases, a mismatch of 1 vertebral level (not side) was noted for the feeding artery. For the tentorial AVF, only the spinal drainage was depicted; the feeding artery was outside the MRA field of view. In intradural SAVM, the main feeding artery was identified by MRA in 10 of 11 patients. MRA could differentiate between glomerular and fistulous SAVM in 4 of 6 cases and between sacral SDAVF and filum terminale SAVM in 2 of 5 cases.

CONCLUSIONS

MRA reliably detects or excludes various types of spinal AV abnormalities and localizes the (predominant) arterial feeder of most spinal AV shunts. Although classification of the subtype of SAVMs remains difficult, with MRA it greatly helps to focus subsequent DSA.

Nouvelles techniques en imagerie vasculaire cervico-encéphalique et médullaire

Recent technical progress of MRI and CT made it possible to widen the field of exploration of the noninvasive vascular imaging in the study of supra-aortic, encephalic and medullary vessels. MRI of the carotid plaques, CT angiography in the detection of the intracranial aneurysms, intracranial time-resolved MRA and MRA of the spinal cord took their place in the field of the noninvasive vascular imaging.

Surgical management of cervical spine osteoblastomas

The treatment of cervical spine osteoblastomas requires complex therapeutic and reconstructive strategies depending on the tumor's location, local aggressiveness, and proximity to the surrounding neurovascular structures. Despite careful removal, lesions recur in as much as 10% of patients. Preoperative embolization is useful to minimize intraoperative bleeding and decrease the relapse of vascular tumors, but its role in osteoblastoma surgery is yet to be defined. We asked whether preoperative embolization with marginal resection would lead to osteoblastoma recurrence, and whether marginal excision with reconstruction would improve neurologic symptoms. We retrospectively analyzed a consecutive series of patients with cervical spine osteoblastoma, treated by one surgeon with a combined approach of preoperative embolization, marginal excision, and spinal reconstruction. One of nine patients presented with a monoradiculopathy, whereas only two patients presented with symptomatic spinal cord compression. At followup, all patients showed neurologic improvement, no tumor relapse, and adequate bony healing. Followup imaging studies showed cervical alignment was maintained. Although we report only a small uncontrolled cohort, the data suggest preoperative embolization and a tumor-free margin are consistent with a prolonged disease-free interval or complete tumor eradication.

Avoiding neurologic complications following ligation of the segmental vessels during anterior instrumentation of the thoracolumbar spine

STUDY DESIGN

A retrospective evaluation of anterior instrumentation of the vertebral bodies in the thoracolumbar spine.

OBJECTIVE

To evaluate the possibility of preserving the segmental vessels following anterior instrumentation.

SUMMARY OF BACKGROUND DATA

Occlusion of the segmental vessels, routinely performed during anterior spine instrumentation, might cause neurologic injury secondary to cord ischemia.

METHODS

The medical data of 29 patients following anterior instrumentation of the vertebral bodies at the thoracolumbar spine were reviewed. All underwent surgery recently when we decided to preserve the segmental vessels whenever possible. We sought the reasons that enabled us to do so regarding age, gender, underlying pathology, surgical technique, operation duration, instrumentation type and size, and location in the vertebral body.

RESULTS

In only 7 patients, fused between T10 and L5, were we able to preserve the segmental vessels. All were instrumented with one 6.25-7-mm wide screw in each vertebral body connected by one rod, approximately half the screws above and half below the segmental vessels. In 22 patients, we were unable to preserve the vessels due to the need to insert 2 screws or a large threaded wide vertebral cage into each vertebra.

CONCLUSIONS

There is adequate space anteriorly in the vertebral body, above and below the segmental vessels, for the insertion of one screw, even with staples.

Double-subtraction maximum intensity projection MR angiography for detecting the artery of Adamkiewicz and differentiating it from the drainage vein

PURPOSE

To evaluate the efficacy of double-subtraction magnetic resonance angiography (MRA) (subtraction of the subtracted venous phase image from the subtracted arterial dominant phase image) for depicting the artery of Adamkiewicz and differentiating it from the drainage vein.

MATERIALS AND METHODS

A total of 170 patients (123 men, 47 women; aged 17-84 years, mean = 67 years), with a thoracoabdominal vascular lesion underwent MRA for detection of the artery of Adamkiewicz. MRA was performed as a five-phase dynamic-enhanced three-dimensional (3D) fast spoiled gradient recalled acquisition in steady state (GRASS) sequence on a 1.5-T system, with double-dose bolus contrast and saline injection. The levels at which the artery of Adamkiewicz and drainage vein originated were determined. Signal intensities of the two vessels were measured with source images to assess the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and necessity of the double-subtraction technique.

RESULTS

The artery of Adamkiewicz was detected in 140 patients (82.4%). Branching occurred at levels T8-T12 on the left and T8-T11 on the right. An additional anterior radiculomedullary artery was detected in 18 patients. The drainage vein was detected in 133 patients (78.2%). It merged at the T9-L2 level on both sides. In six of the 133 patients (4.5%), the drainage vein branched upwardly. Neither SNR nor CNR differed significantly between the artery of Adamkiewicz and the drainage vein in the arterial phase; but on the subtraction image, signal intensity of the artery was higher than that of the drainage vein (P < 0.05).

CONCLUSION

Double-subtraction MRA is useful for detecting the artery of Adamkiewicz when it is necessary to differentiate it from the drainage vein.

[Imaging of spinal tumors]

Spinal tumors are often categorized into extradural, intradural extramedullary, or intramedullary. Although this classification represents somewhat of an overgeneralization as a lesion may reside in two compartments, it still helps to characterize spinal tumors. In the intradural, extramedullary space, primary tumors, such as neurofibroma and meningioma, are relatively common. Secondary tumors or leptomeningeal enhancement also occur. In the intramedullary space, primary tumors are far more common than secondary tumors or metastases.

[Spinal dural arteriovenous fistula with peri-medullary venous drainage: analysis of a series from a single centre and review of the literature]

INTRODUCTION

The optimal diagnosis and therapeutic managements of spinal dural arteriovenous fistulae, a rare disease, is discussed.

MATERIAL AND METHODS

We report a series of 10 patients seen in a 7-year period, treated by embolization.

RESULTS

There were 6 males and 4 females, with an average age of 58.4 years (range: 31 to 74 years). Diagnosis was made 2 days to 5 years (mean 15.3 months) after symptom onset with a high rate of incomplete or atypical clinical patterns (prolonged isolated sensory disorder, lumbo-sciatalgia, claudication, monoplegia), or sudden-onset deficit. In all cases, spinal MRI showed an intramedullary high-intensity signal on T2-weighted images but enlarged intradural vessels in only 70p.cent of cases. Angiography showed in all cases an arteriovenous fistula at the upper dorsal level (T1 to T7, 5 cases), lower dorsal (T8-T12, in 3 cases) and lumbar levels (2 cases). The fistula was successfully obliterated after initial embolization in 3 cases, but two (2 cases) or 3 procedures (2 cases) were sometimes required. The endovascular therapy failed in 3 cases.

CONCLUSION

In this series, the fistula was successfully obliterated in 70p.cent of patients. In the literature, fistula of 96.8p.cent to 97.9p.cent of patients were obliterated by surgery, which is a more invasive treatment. Embolization could be used as the first-line therapy, but incomplete obliteration requires rapid surgery. While the success of embolization is demonstrated, MRI and angiography must still be performed 6 months later.

The role of non-invasive computed tomography in patients with suspected dural fistulas with spinal drainage

OBJECTIVE

Accurate diagnosis and demonstration of the angioarchitecture and localization of a spinal dural arteriovenous fistula is of crucial importance before treatment. Selective spinal angiography (DSA) has been considered the standard technique, but is invasive, time-consuming, and may be falsely negative. This report evaluates the use of noninvasive vascular imaging (computed tomographic and magnetic resonance angiography [MRA]) in patients suspected to have a dural fistula with spinal drainage.

METHOD

Ten consecutive patients had DSA and multidetector computed tomographic angiography (MDCTA), eight also had MRA. Nine were men with an average age of 67 years. In nine patients, the diagnosis was confirmed at surgery or intravascular treatment. Eight were proven to have a spinal dural fistula. In two, the fistula was within the cervical cranial dura. In all patients, the venous drainage involved only the spinal venous plexus.

RESULTS

MDCTA identified the level of the feeding artery in nine patients. In two cases, selective DSA failed to show the abnormality found on MDCTA, but both were confirmed at surgery. MRA was diagnostic in a case in which the lesion was not accurately depicted by either MDCTA or DSA. MRA was less accurate than MDCTA in determining the level of the feeding artery.

CONCLUSION

MDCTA and MRA can direct and focus DSA. MDCTA gives additional useful three-dimensional bone detail and localization information for the surgeon. It may replace DSA if surgery is the planned treatment.

Spinal dural arteriovenous fistula

PURPOSE OF REVIEW

To summarize clinical key points, diagnostic features, and results of imaging and therapy of spinal dural arteriovenous fistula (SDAVF).

RECENT FINDINGS

SDAVF accounts for 70% of spinal arteriovenous malformation with an annual incidence of 5-10 cases per million. At least 80% of patients are male, and more than 66% of patients are in the sixth and seventh decade of life indicating preponderance of gender and age. Thrombophilia is not a predisposing factor of disease. Clinical course is predominated by symptoms of congestive myelopathy, but subarachnoid hemorrhage may occur. Double SDAVF is a rare problem in the management of disease. Magnetic resonance imaging has replaced myelography as screening procedure. Contrast-enhanced magnetic resonance angiography and multislice computerized tomographic angiography may facilitate diagnostic procedure, however, spinal angiography is still required to confirm diagnosis. Treatment by permanent occlusion of fistula results in clinical improvement in 70% of cases. Microsurgical shunt interruption has proven secure and reliable. Endovascular shunt embolization has been established as a standardized procedure, but occlusion rates are still lower than in surgical treatment.

SUMMARY

Advances have been made in diagnosis and treatment of SDAVF, but the disease is still not completely understood.

Thoracic Spinal Cord Ischemia Following Acute Myocardial Infarction and Cardiac Arrest in a Young Male

In an era of percutaneous stenting for acute myocardial infarction (AMI), a case of thoracic spinal cord ischemia following AMI and cardiac arrest is presented, to highlight and discuss this rare but debilitating condition, well-documented within the neurological literature, but rarely encountered in cardiovascular practice.

Comparison of 0.5-M Gd-DTPA with 1.0-M gadobutrol for magnetic resonance angiography of the supplying arteries of the spinal cord in thoracoabdominal aortic aneurysm patients

PURPOSE

To prospectively compare 0.5-M gadopentetate dimeglumine (Gd-DTPA) with 1.0-M gadobutrol for contrast-enhanced magnetic resonance angiography (CE-MRA) of the blood supplying arteries of the spinal cord in patients referred for open surgical repair of a thoracoabdominal aortic aneurysm (TAAA).

MATERIALS AND METHODS

A total of 11 patients with a TAAA underwent two three-dimensional CE-MRA exams of the aorta, segmental arteries (SAs), artery of Adamkiewicz (AKA), and anterior spinal artery (ASA). Imaging was performed on two separate occasions using Gd-DTPA and gadobutrol as contrast agents at 0.3 mmol/kg. Images were evaluated by measuring signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and were judged for different image quality criteria by two blinded observers.

RESULTS

In all patients both CE-MRA exams were of sufficient image quality to detect the AKA and ASA. No significant differences in SNR and CNR were observed between the two contrast agents. According to the observers, no significant differences in subjective image quality were found.

CONCLUSIONS

Using both contrast agents it was possible to visualize the ultrasmall spinal cord arteries in all cases. The use of the 1.0-M contrast agent did not improve image quality of CE-MRA images of the blood supplying arteries of the spinal cord compared to the 0.5-M contrast agent.