Advances in spinal cord MR angiography

Diagnostic Accuracy of 4D-MRA for the Detection and Localization of Spinal Dural Arteriovenous Fistulas: A Systematic Review and Meta-Analysis

BACKGROUND

The gold standard for the diagnosis and detailed evaluation of spinal dural arteriovenous fistula (SDAVF) is a digital subtraction angiography (DSA). However, this procedure is time-consuming and effortful. A time-resolved contrast enhanced 4D magnetic resonance angiography (4D-MRA) can be used to increase the diagnostic accuracy of spinal magnetic resonance imaging for the detection and localization of a SDAVF. The goal of this study is to assess the diagnostic accuracy of 4D-MRA for the detection and localization of a SDAVF in comparison to DSA based on a systematic review of the literature.

METHODS

We performed a systematic review and meta-analysis on the diagnostic accuracy of 4D-MRA compared to DSA. Literature was reviewed from the PubMed, Cochrane, and EMBASE databases.

RESULTS

In comparison with DSA, the pooled sensitivity of MRA was 98.2% (95% confidence interval [CI] 91.5%-99.6%), with a pooled specificity of 88.2% (95% CI 57.5%-97.6%) for the diagnosis of SDAVFs. The side and level of the SDAVFs were correct in 91% (95% CI: 86%-94%) and 76% (95% CI: 71%-80%), respectively.

CONCLUSIONS

Current literature indicates that 4D-MRA has a high sensitivity and specificity for the detection and localization of a SDAVF. It can serve to guide DSA to shorten the procedural time, reduce the risk of complications, and decrease patient discomfort.

Diagnostic accuracy of 4D-MRA for the detection and localization of spinal dural arteriovenous fistulas: A retrospective 10-year cohort study

Research question

The goal of this study was to assess the diagnostic accuracy of spinal time-resolved contrast-enhanced MR angiography (4D-MRA) for the detection and localization of spinal dural arteriovenous fistulas (SDAVF) in our institution.

Material and methods

Single center retrospective cohort study of patients with the clinical suspicion of a SDAVF. Patients were included who had undergone spinal 4D-MRA in the period January 2010-February 2021. A subgroup was identified, who had subsequent digital subtraction angiography (DSA), or clinical/radiological follow-up. Diagnostic performance measures of 4D-MRA were calculated (sensitivity, positive predictive value, specificity, and negative predictive value) with DSA serving as the reference standard.

Results

Overall, 120 patients with the clinical suspicion of having a SDAVF and who underwent spinal 4D-MRA were identified. A subgroup of 30 patients had both 4D-MRA and DSA, or follow-up. In this group, the sensitivity of 4D-MRA for the detection of a SDAVF was 100% and specificity was 91% (positive predictive value of 95% and a negative predictive value of 100%). Sidedness was correctly identified on 4D-MRA in 74% of the cases and the level of the SDAVF in 68%.

Discussion and conclusion

The results indicate that 4D-MRA has a high sensitivity and specificity for the detection and localization of a SDAVF, which is in line with previous studies published in literature. Furthermore, 4D-MRA can serve to guide DSA and shorten the procedural time, which reduces the risk of angiography related complications, and decreases patient discomfort.

What the Musculoskeletal Radiologist Needs to Know About the Vascular Anatomy of the Spine and Spinal Cord

This article describes the vascular anatomy of the spine and spinal cord, highlighting key structures and anatomical variations relevant to musculoskeletal radiologists. It covers the arterial and venous drainage systems, along with examples of vascular conditions affecting the spine. Understanding the vascular anatomy of the spine and spinal cord is crucial for accurate interpretation of imaging studies and safe spinal interventional procedures. Imaging techniques for evaluating vascular pathology of the spine are discussed and compared. Understanding vascular anatomy and the most common vascular disorders will lead to an accurate diagnosis and suggest the appropriate type of study needed for further characterization and/or patient management.

Anatomical study of the thoracolumbar radiculomedullary arteries, including the Adamkiewicz artery and supporting radiculomedullary arteries

OBJECTIVE

The aim of this paper was to identify and characterize all the segmental radiculomedullary arteries (RMAs) that supply the thoracic and lumbar spinal cord.

METHODS

All RMAs from T4 to L5 were studied systematically in 25 cadaveric specimens. The RMA with the greatest diameter in each specimen was termed the artery of Adamkiewicz (AKA). Other supporting RMAs were also identified and characterized.

RESULTS

A total of 27 AKAs were found in 25 specimens. Twenty-two AKAs (81%) originated from a left thoracic or a left lumbar radicular branch, and 5 (19%) arose from the right. Two specimens (8%) had two AKAs each: one specimen with two AKAs on the left side and the other specimen with one AKA on each side. Eight cadaveric specimens (32%) had 10 additional RMAs; among those, a single additional RMA was found in 6 specimens (75%), and 2 additional RMAs were found in each of the remaining 2 specimens (25%). Of those specimens with a single additional RMA, the supporting RMA was ipsilateral to the AKA in 5 specimens (83%) and contralateral in only 1 specimen (17%). The specimens containing 2 additional RMAs were all (100%) ipsilateral to their respective AKAs.

CONCLUSIONS

The segmental RMAs supplying the thoracic and lumbar spinal cord can be unilateral, bilateral, or multiple. Multiple AKAs or additional RMAs supplying a single anterior spinal artery are common and should be considered when dealing with the spinal cord at the thoracolumbar level.

Spinal cord ischemia complicating treatment of abdominal aortic aneurysms: a legal overview

BACKGROUND AND AIM

Spinal cord ischemia following open or endovascular aneurysm repair of the abdominal aorta is rare but highly disabling complication. The aim of this work is to report on its occurrence and its legal consequences.

METHODS

We report a case of spinal cord ischemia complicating an endovascular aortic repair, its management and sequalae, comparing it with the existing literature and we examine its legal consequences resulting in a malpractice lawsuit and the final decision of the judge.

RESULTS

Although the causal relation between SCI and the neurological deficits reported were assessed by the Court, no element of responsibility imputable to the Hospital or the Medical Staff were found, since the defendant had made every effort to prevent it in the preoperatory setting, and to treat it once it established in the post-operative phase.

CONCLUSIONS

predictable but unpreventable complications of necessary interventions rule out medical malpractice, as long as the patient is fully informed about the risks and benefits of the treatment, and provided that in the perioperative setting all due measures are taken in order to prevent it and treat it.

Fast three-dimensional contrast-enhanced magnetic resonance angiography of the canine lumbar spinal cord vascular supply: A feasibility study

Magnetic resonance angiography (MRA) is the noninvasive spinal cord vascular imaging modality of choice in human medicine. The aim of this exploratory, prospective, descriptive study was to assess the feasibility of fast three-dimensional (3D) contrast-enhanced (CE) MRA for visualization of spinal vascular structures in the canine lumbar region. Fourteen canine patients weighing > 5 kg were included. The lumbar arteries were consistently visualized (14/14;100%). Spinal arteries, radicular branches, great radicular artery (of Adamkiewicz), ventral spinal artery, and dorsal spinal arteries were not visualized (0/14;0%). The internal vertebral venous plexus was visualized in 11 of 14 (79%) dogs. Overall, the results of this study show that fast 3D CE-MRA of the lumbar region in dogs is feasible. However, the smaller arteries responsible for the spinal cord vascular supply were not visualized in this study.

Feasibility of Noninvasive Diagnosis of Spinal Vascular Diseases Using Time-Resolved Angiography With Stochastic Trajectories

Background and Purpose: To determine the feasibility of time-resolved angiography with stochastic trajectories (TWIST) in the diagnosis of spinal dural arteriovenous fistula (SDAVF) and perimedullary arteriovenous fistula (PAVF).

Methods: A total of 11 negative patients with TWIST examination were retrospective analyzed and then 18 patients with suspected spinal vascular diseases underwent TWIST. For negative patients, Adamkiewicz artery (AKA), great anterior radiculomedullary vein (GARV) and anterior spinal artery (ASA) were retrospective analyzed. In patients, the results of TWIST were compared with those of DSA.

Results: The displaying rates of the ASA, AKA and GARV in 11 negative patients were 100, 90.9, and 90.9%, respectively. The AKA and GARV were separated on TWIST. Of 18 patients, 11 and three were diagnosed with SDAVF and PAVF, respectively. The spinal cord vascular malformation diagnosed on TWIST was consistent with DSA with an excellent intermodality agreement (Kappa = 0.92, p < 0.001). The feeding artery and side of all 11 SDAVF patients were displayed on TWIST and the results were consistent with DSA. For PAVF patients, the feeding artery in two patients and the sides as displayed on TWIST were consistent with DSA.

Conclusions: TWIST enables the differentiation of the spinal artery and vein and the differential diagnosis of SDAVF and PAVF.

The Relevance of Preoperative Identification of the Adamkiewicz Artery in Posterior Mediastinal Pediatric Tumors

Background

Injury to the artery of Adamkiewicz (AKA) during surgery may lead to spinal cord ischemia and severe neurologic complications. Posterior mediastinal tumors may be adjacent to AKA, but data on preoperative visualization of AKA in children are rare. This study analyzed the importance of identifying the AKA preoperatively by spinal digital subtraction angiography (DSA) in children with posterior mediastinal tumors for therapeutic procedure.

Methods

Between 2002 and 2021, 36 children with posterior mediastinal tumors were evaluated for surgery at the authors’ clinic. In 10 children with left-sided or bilateral tumor located at vertebral levels T8 to L1, spinal DSA was performed during preoperative workup to assess AKA. The patient and tumor characteristics as well as the diagnostic and therapeutic procedures were analyzed.

Results

The median age of the 10 children at examination was 69 months (range, 16–217 months). Three of the children were younger than 2 years. The tumor entities were neuroblastoma, ganglioneuroblastoma, ganglioneuroma, local relapse of a hepatocellular carcinoma, and neurofibroma. The AKA was identified in all cases, and proximity to the tumor was detected in four patients, three of whom had their planned surgery changed to irradiation. No complications occurred during spinal DSA or surgery.

Conclusions

In posterior mediastinal pediatric tumors, spinal DSA is a safe and reliable method for preoperative visualization of the AKA. It can show proximity to the tumor and guide the local therapy, thereby avoiding critical intra- and postoperative situations.

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.

Anatomy of the Great Posterior Radiculomedullary Artery

BACKGROUND AND PURPOSE

Although considerable variability exists as to the overall caliber of radiculomedullary arteries, dominant radiculomedullary arteries such as the artery of Adamkiewicz exist. The existence of a great posterior radiculomedullary artery has attracted little attention and has been a matter of debate. The aim of this anatomic study was to determine the presence or absence of the great posterior radiculomedullary artery.

MATERIALS AND METHODS

We performed microsurgical dissection on formaldehyde-fixed cadaveric human spinal cords. The artery of Adamkiewicz in the spinal cord specimens (n = 50) was injected with colored latex until the small-caliber arterial vessels were filled and the great posterior radiculomedullary artery was identified. The course, diameter, and location of great posterior radiculomedullary artery were documented.

RESULTS

A great posterior radiculomedullary artery was identified in 36 (72%) spinal cord specimens. In 11 (22%) specimens, bilateral great posterior radiculomedullary arteries were present. In 13 cases (26%), a unilateral left-sided great posterior radiculomedullary artery was identified. In 11 cases (22%), a unilateral right-sided great posterior radiculomedullary artery was identified. In 1 specimen (2%), 3 right-sided great posterior radiculomedullary arteries were noted. The average size of the great posterior radiculomedullary arteries was 0.44 mm (range, 0.120-0.678 mm on the left and 0.260-0.635 mm on the right).

CONCLUSIONS

A great posterior radiculomedullary artery is present in most (72%) individuals. The authors describe the microsurgical anatomy of the great posterior radiculomedullary artery with emphasis on its morphometric parameters as well as its implications for spinal cord blood supply. Variations of the arterial supply to the dorsal cord are of great importance due to their implications for ischemic events, endovascular procedures, and surgical approaches.

New insights into spinal cord ischaemia after thoracic aortic procedures: the importance of the number of anterior radiculomedullary arteries for surgical outcome

OBJECTIVES

Anterior radiculomedullary arteries (ARMAs) link dorsal segmental arteries and the intraspinal compartment of the spinal collateral network. The number of thoracic ARMA is highly variable from one person to another. The impact of the number of ARMAs on spinal cord perfusion during thoracic aortic procedures is unknown. We investigated the influence of the number of thoracic ARMAs on spinal cord perfusion in an aortic surgical large animal model.

METHODS

Twenty-six pigs were included (20 treatment animals, 6 sham animals, weight 34 ± 3 kg). The animals underwent ligation of the left subclavian artery and the thoracic segmental arteries via a left lateral thoracotomy with normothermia. After sacrifice, complete body perfusion with coloured cast resin was performed and the number of thoracic ARMAs was documented at autopsy. End points were spinal cord perfusion pressure, cerebrospinal fluid pressure, spinal cord blood flow (microspheres) and neurological outcome. Observation time was 3 h post-ligation.

RESULTS

The numbers of thoracic ARMAs ranged between 3 (n = 1) and 13 (n = 1). The mean number was 8. Animals were grouped according to number of thoracic ARMA: 6-7 (5 animals), 8-10 (8 animals) and 11-13 (5 animals). A large number of thoracic ARMAs was linked to (i) a lower drop in spinal cord blood flow from baseline to post-clamp, (ii) the presence and increased magnitude of hyperaemia evident 3 h post-clamp (P < 0.001) and (iii) the presence of early hyperaemia starting immediately post-clamp in animals with 11 or more ARMA (P < 0.001).

CONCLUSIONS

We showed that a large number of thoracic ARMA protects against spinal cord injury during descending aortic surgical procedures.1.

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.

Diagnostic accuracy and efficiency of combined acquisition of low-dose time-resolved and single-phase high-resolution contrast-enhanced magnetic resonance angiography in a single session for pre-angiographic evaluation of spinal vascular disease

Background/Purpose

The purpose of this study was to evaluate the utility and efficacy of combined low-dose, time-resolved (TR) and single-phase high-resolution (HR) contrast-enhanced MRA (CE-MRA) as a pre-angiographic study for spinal vascular disease.

Materials and methods

Seventeen consecutive patients with suspected spinal vascular disease were retrospectively reviewed. All patients underwent combined low-dose TR CE-MRA and three-dimensional single-phase HR CE-MRA at 3 Tesla, followed by conventional spinal digital subtraction angiography (DSA) within 90 days. Six patients underwent additional spinal MRA and DSA for treatment follow-up. Spinal lesions were analyzed in terms of presence, disease type, laterality, spinal level, and number of arterial feeders.

Results

Low-dose TR CE-MRA helped proper localization of subsequent HR CE-MRA in two patients with high or low level of the lesion. For initial detection of spinal vascular disease, sensitivity, specificity and accuracy of CE-MRA were 93.3% (n = 14/15), 100% (n = 3/3), and 94.4% (n = 17/18), respectively. In characterization of dural arteriovenous fistula (AVF), perimedullary AVF, spinal cord arteriovenous malformation (AVM), and extraspinal AVM, CE-MRA correctly characterized in 86.7% (n = 13/15) among the positive findings, and in 88.9% (n = 16/18) among the several patients including negative results. CE-MRA showed matched per-case localization of arterial feeders within 1 vertebral level in 80% (n = 12/15), and matched per-lesion localization in 78.3% (n = 18/23).

Conclusion

Combined low-dose TR CE-MRA and single-phase HR CE-MRA at 3 Tesla was an effective and accurate non-invasive tool for the pre-angiographic evaluation of spinal vascular diseases in a single session.

Spinal Ischemia in Thoracic Aortic Procedures: Impact of Radiculomedullary Artery Distribution

BACKGROUND

The aim of this study was to assess the influence of thoracic anterior radiculomedullary artery (tARMA) distribution on spinal cord perfusion in a thoracic aortic surgical model.

METHODS

Twenty-six pigs (34 ± 3 kg; study group, n = 20; sham group, n = 6) underwent ligation of the left subclavian artery and thoracic segmental arteries. End points were spinal cord perfusion pressure (SCPP), regional spinal cord blood flow (SCBF), and neurologic outcome with an observation time of 3 hours. tARMA distribution patterns tested for an effect on end points included (1) maximum distance between any 2 tARMAs within the treated aortic segment (0 or 1 segment = small-distance group; >1 segment = large-distance group) and (2) distance between the end of the treated aortic segment and the first distal tARMA (at the level of the distal simulated stent-graft end = group 0; gap of 1 or more segments = group ≥1).

RESULTS

The number of tARMA ranged from 3 to 13 (mean, 8). In the large-distance group, SCBF dropped from 0.48 ± 0.16 mL/g/min to 0.3 ± 0.08 mL/g/min (p < 0.001). We observed no detectable SCBF drop in the small-distance group: 0.2 ± 0.05 mL/g/min at baseline to 0.23 ± 0.05 mL/g/min immediately after clamping (p = 0.147). SCBF increased from 0.201 ± 0.055 mL/g/min at baseline to 0.443 ± 0.051 mL/g/min at 3 hours postoperatively (p < 0.001) only in the small-distance group.

CONCLUSIONS

We demonstrate experimental data showing that distribution patterns of tARMAs correlate with the degree of SCBF drop and insufficient reactive parenchymal hyperemia in aortic procedures. Individual ARMA distribution patterns along the treated aortic segment could help us predict the individual risk of spinal ischemia.

Serial magnetic resonance imaging findings in subarachnoid hemorrhage due to an initially angiographically occult type II spinal aneurysm: Case report

Background: Spinal aneurysms are rare causes of spontaneous subarachnoid hemorrhage. Methods: We present an unusual, initially occult, case of an upper thoracic intradural extramedullary isolated aneurysm arising from the T2 intercostal-radicular circulation that was initially angiographically occult but was discovered due to unique, albeit nonspecific, magnetic resonance imaging findings of spinal cord T2 hyperintensity and contrast enhancement that were noted to progress with a clinical picture of ictal rehemorrhage. Results: Repeat spinal angiography revealed a spinal aneurysm that was treated surgically. Conclusion: In cases of sufficient clinical suspicion and nonspecific imaging findings, continued vigilance is advised in seeking an underlying pathoanatomic etiology. (www.actabiomedica.it)

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.

Dynamic contrast-enhanced magnetic resonance angiography for the localization of spinal dural arteriovenous fistulas at 3T

OBJECTIVE

This study was undertaken to evaluate the accuracy of dynamic contrast-enhanced magnetic resonance angiography (DCE-MRA) in the precise location and demonstration of fistulous points in spinal dural arteriovenous fistulas (SDAVFs).

METHODS

Fifteen patients (14 men, 1 woman; age range: 40-78 years; mean: 55.5 years) harboring SDAVF who underwent preoperative DCE-MRA and spinal digital subtraction angiography (DSA) between January 2012 and January 2015 were evaluated retrospectively. Two reviewers independently evaluated the level and side of the arteriovenous fistula and feeding artery on 3T DCE-MRA and DSA images. The accuracy of DCE-MRA was assessed by comparing its findings with those from DSA and surgery in each case.

RESULTS

All 15 patients underwent DCE-MRA and DSA. DSA was unsuccessful in two patients due to technical difficulties. All cases were explored surgically, guided by the DCE-MRA. Surgery confirmed that 14 AVF sites were located in the thoracic spine, 5 in the lumbar spine, and 1 in the cervical spine. The origin of the fistulas and feeding arteries was accurately shown by DCE-MRA in 11 of the 15 patients. DCE-MRA also detected dilated perimedullary veins in all 15 patients. Overall, DCE-MRA facilitated DSA catheterization in 10 cases. In six patients, the artery of Adamkiewicz could be observed. In 15 out of 20 fistulas (75%), both readers agreed on the location on DCE-MRA images, and the κ coefficient of the interobserver agreement was 0.67 (95% confidence interval [CI], 0.16-0.87). In 13 of 16 shunts (75%), the DCE-MRA consensus findings and DSA findings coincided. The intermodality agreement was 0.77 (95% CI: 0.35-0.92).

CONCLUSIONS

Our DCE-MRA studies benefited from the use of a high-field 3T MR imaging unit and reliably detected and localized the SDAVF and feeding arteries. As experience with this technique grows, it may be possible to replace DSA with DCE-MRA if surgery is the planned treatment.

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.

How to image patients with spine pain

Different radiological methods play an important role in the work-up of patients complaining of spine pain. Depending on the symptoms and the suspected underlying etiology different methods are selected. In the following presentation we briefly present the different radiological and magnetic resonance tomography methods that are at hand, give some guidance in which method to use, and present the typical imaging findings in some of the most common conditions that presents with spine pain.

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.

Novel application of 3-dimensional rotational C-arm conebeam computed tomography angiography for metastatic hypervascular tumor mass in the spine

STUDY DESIGN

This is a case report.

OBJECTIVE

To report a 3-dimensional (3D) rotational C-arm conebeam computed tomography (CT) (DynaCT) angiography generating computed tomographic data concurrently with spinal angiographic datasets. This technology allowed 3D modeling of the anterior spinal arterial supply in juxtaposition to a hypervascular tumor mass, thus affording unprecedented guidance in presurgical planning.

SUMMARY OF BACKGROUND DATA

An enhanced demonstration of spatial relationships between the vascular elements and their adjacent soft-tissue structures is needed to visualize the minute anterior spinal artery optimally.

METHODS

A 76-year-old male with a history of renal cell carcinoma metastasis to the T6 vertebra 1 year prior, presented with worsening myelopathy caused by severe spinal cord compression at T6 level, and a plan for surgical decompression was established. Because of the hypervascular nature of this renal cell carcinoma metastasis, preoperative embolization was requested to minimize blood loss during the operation. A digital subtraction angiogram identified the major arterial contribution to the tumor to also supply the radiculomedullary branch to the anterior spinal artery. To further characterize this blood supply, a rotational DynaCT angiography was performed.

RESULTS

The rotationally acquired data were processed generating volumetric CT datasets demonstrating the 3D relationships of the anterior spinal artery, the blood supply to the tumor and the adjacent soft-tissue and bony structures. A shared blood supply to both the tumor mass and the anterior spinal artery from the left T6 segmental artery was confirmed. The dual nature of this blood supply presented increased risk of ischemic spinal cord injury by possible nontarget embolization. Therefore, the embolization was deferred.

CONCLUSION

The DynaCT angiography precisely characterized the complex blood supply of a hypervascular vertebral tumor mass in relation to a shared arterial supply to the thoracic spinal cord. The optimal visualization properly aided presurgical planning.

LEVEL OF EVIDENCE

N/A.

Cognard Type V Intracranial Dural Arteriovenous Shunt

BACKGROUND AND IMPORTANCE:

Prompt diagnosis of intracranial dural arteriovenous shunt (DAVS) with spinal venous drainage, classified as Cognard type V, is difficult. We investigated the angiographic and magnetic resonance imaging (MRI) characteristics of Cognard type V DAVS to determine the reason for the difficulty in early diagnosis.

CLINICAL PRESENTATION:

We systematically reviewed 54 published and 3 new cases of Cognard type V DAVS. The pattern of venous drainage was classified on the basis of relative dominance of the anterior and posterior spinal veins with the use of angiograms. T2-weighted sagittal MRIs were used to detect signal flow voids of enlarged spinal veins. Types of venous drainage were determined in 49 of the 57 cases. Twenty-eight and 8 cases showed a dominance of anterior and posterior spinal venous drainage, respectively. In 13 cases, venous drainage was equally distributed through the anterior and posterior spinal veins. Of 41 cases with an abnormally dilated anterior spinal vein, MRIs were available for 25 cases. Signal flow voids of enlarged anterior spinal veins were detected in 9 cases (36.0%), whereas dilatation of the posterior spinal veins was apparent in 9 of 16 cases (56.3%). Overall, MRI detected enlargement of either anterior or posterior spinal veins in 15 of 41 cases (36.6%).

CONCLUSION:

In Cognard type V DAVS, anterior venous drainage is dominant. Because the anterior spinal veins are located subpially, flow voids are less prominent on sagittal T2-weighted MRI. This may lead to difficulties in diagnosing. Evaluation with MR angiography may compensate for these limitations.

Spinal dural fistulas without swelling and edema of the cord as incidental findings

SUMMARY

SDAVFs cause hypertension and hence outflow obstruction in the perimedullary venous system resulting in swelling and edema of the cord followed by dysfunction. Clinical presentation is usually with gradual progressive paraparesis, numbness, and sphincter problems. MR imaging typically demonstrates the dilated perimedullary veins and the swelling and edema of the cord. During the past few years, we incidentally found an SDAVF on MR imaging with dilated perimedullary veins but without swelling and edema of the cord in 5 patients with unrelated presenting clinical symptoms. Spinal angiography confirmed the presence of an SDAVF in all 5 patients. Although the indication was considered questionable, eventually all 5 fistulas were endovascularly or surgically treated, resulting in normalization of the MR images.

Neuroradiology back to the future: spine imaging

Although radiography of the spine began shortly after Roentgen's discovery in 1895, there was little written in the medical literature about spine imaging until nearly 25 years later with the development of myelography, first by using air and then a variety of positive contrast agents. The history of spine imaging before CT and MR imaging is, in large part, a history of the development of contrast agents for intrathecal use. The advent of CT and, more important, MR imaging revolutionized spine imaging. The spinal cord and its surrounding structures could now be noninvasively visualized in great detail. In situations in which myelography is still necessary, advances in contrast agents have made the procedure less painful with fewer side effects. In this historical review, we will trace the evolution of spine imaging that has led to less invasive techniques for the evaluation of the spine and its contents and has resulted in more rapid, more specific diagnosis, therapy, and improved outcomes.

Open repair of extensive thoracoabdominal and thoracic aneurysm: a preliminary single-center experience with femorofemoral distal aortic perfusion with oxygenator and without cerebrospinal fluid drainage

Thoracoabdominal aortic aneurysms (TAAA) and extensive thoracic descending aortic aneurysms (TDA) are not accessible through standard endovascular treatment. Fenestrated and branched endograft technology was developed rapidly without widespread application. The aim of this study was to review our open repair (OR) experience of TAAA and TDA. A total of 28 patients who underwent elective OR of TAAA or TDA between January 2001 and January 2009 were analyzed retrospectively. The mean age of the patients was 65.5 years (three women). The anatomic locations of the aneurysms were as follows: six in thoracic descending aorta and 22 in thoracoabdominal aorta (14 TAAA I, two TAAA II, six TAAA III). TDA (40 patients) available for ordinary endovascular treatment and TAAA IV (35 patients) were excluded from this study. To focus on spinal cord vascularization, 25 patients were submitted for angiography. Three patients suffering from back pain required quick treatment and were excluded from angiographic investigations. Angiography procedures were contributive in 23 patients (92%). Surgical repairs were driven through left thoraco-phreno-laparotomy, with the adjunct of distal aortic perfusion (femorofemoral bypass) including the use of an oxygenator and sequential aortic cross-clamping. Cerebrospinal fluid drainage was not used in this experience. The 30-day mortality rate was 14.3% (four of 28 patients): one multiorgan failure and three pulmonary sepsis. An immediate postoperative paraplegia occurred, affecting a patient with TDA who was previously submitted for infrarenal aorta replacement, despite angiographic identification and revascularization of intercostal artery destined to spinal artery. The 1-year survival rate was 82.1% (23 of 28 patients). In the preliminary experience of this study, OR of extensive TAAA and TDA with distal aortic perfusion and an oxygenator without use of cerebrospinal fluid drainage was associated with a significant perioperative mortality rate (14.2%), a reasonable rate of paraplegia (3%), and 1-year survival rate of 82.1%.

[Imaging of non-traumatic and non-tumoral cord lesions]

There is a wide range of spinal cord pathologies (vascular, inflammatory, infectious, metabolic, degenerative). They present clinically as acute partial or complete cord syndromes, or chronic myelopathies (more than 4 weeks in duration). MRI examination should be undertaken with a very strict protocol. Spinal cord lesions should be evaluated with regards to their T1W and T2W signal characteristics, involvement of grey and/or white matter, axial and sagittal extension, cord volume changes, contrast uptake and associated lesions (perimedullary, radicular or brain). The correlation of MR imaging features with clinical and biological data (blood and CSF) should suggest a differential diagnosis.

Dynamic MR angiography (MRA) of spinal vascular diseases at 3T

Spinal magnetic resonance angiography (MRA) is difficult to perform because of the size of the spinal cord vessels. High-field MR improves resolution and imaging speed. We examined 17 patients with spinal vascular diseases with dynamic contrast-enhanced three-dimensional MR sequences. In three patients, the artery of Adamkievicz could be seen; we could also detect all arteriovenous malformations and dural fistulas. MRA has the potential to replace diagnostic spinal angiography and the latter should be used only for therapeutic purposes.

A Little Talk on Adamkiewicz's Artery. Some Practical Considerations on the Pre-Operative Identification of this Artery Starting from a Single Team Experience in Pre-Surgical Selective Embolization of Vascularized Spinal Lesions

The major radicular artery eponymically named "Adamkiewicz's artery" (AKA) is an important vessel supplying the spinal cord, especially the lumbar enlargement. This report emphasizes the importance of anatomical knowledge of this artery and highlights the concept of the potential risk of neurological complications during different procedures: spine orthopedic/neurosurgery, aortic repair (vascular surgery) and endovascular selective embolizations performed by interventional neuro/radiologists. Anatomical considerations are made on the spinal cord arterial circulation with a special focus on the AKA. Our review of the literature considered this anatomical element essential to compare the potential risk of spinal cord ischemic damage during orthopedic/neurosurgical spine procedures, aortic vascular surgery repair procedures and endovascular selective arterial embolizations. Evaluation of the endovascular selective arterial spine embolization risk was based on our series of 410 embolization procedures. Spinal cord infarction and transient or permanent paraplegia may result from inadvertent interruption of the AKA. The presence of intersegmental collaterals may decrease the risk of spinal cord ischemia: this is an important element to bear in mind that may help in spine surgery or aortic repair procedures performed by vascular surgeons. Nevertheless, during aortic repair (open surgery or stent-graft procedures) interruption of bilateral segmental arteries at multiple consecutive levels including that of the AKA may occur thereby increasing the ischemic spinal cord risk, annulling the benefit of intersegmental collaterals. Accidental embolizations of the AKA during endovascular spine procedures (i.e. selective arterial embolizations) performed by interventional neuro/radiologists will cause an almost certain spinal cord infarction due to the consequent embolizations of the anterior spinal artery (ASA).

Comparison of gadobenate dimeglumine and gadodiamide in the evaluation of spinal vascular anatomy with MR angiography

BACKGROUND AND PURPOSE

Spinal MRA has been increasingly used to evaluate non-invasively the spinal cord vasculature. Our aim was to prospectively compare gadobenate dimeglumine with gadodiamide in the assessment of the normal spinal cord vasculature by using contrast-enhanced MRA, with the hypothesis that high T1 relaxivity gadolinium compounds may improve visualization of the intradural vessels.

MATERIALS AND METHODS

Twenty subjects underwent 2 temporally separated contrast-enhanced spinal MRAs with gadobenate dimeglumine and gadodiamide (0.2 mmol/kg). Two blinded observers rated postprocessed images on the following qualitative parameters: background homogeneity, sharpness, vascular continuity, and contrast enhancement. Delineation of the ASA, AKA, hairpin configuration of the ASA-AKA connection, and visualized ASA length were recorded. Each observer indicated which of the 2 matched studies he or she thought was of the best overall diagnostic quality.

RESULTS

According to both observers gadobenate dimeglumine was superior to gadodiamide in the representation of vascular continuity and contrast (P value < .05). Background homogeneity was not significantly different between the studies. One observer favored gadobenate dimeglumine over gadodiamide in the demonstration of vascular sharpness, while the second observer did not find any significant difference between contrast agents. There was no significant difference between contrast agents in the visualization of the ASA, AKA, hairpin-shaped ASA-AKA connection, and visualized length of the ASA. The overall quality of the gadobenate dimeglumine-enhanced MRA was deemed superior in 15 and 16 cases, respectively, by the 2 observers.

CONCLUSIONS

Improved image quality and vascular contrast enhancement of spinal MRA at 1.5T is achieved with high T1 relaxivity gadolinium contrast agents compared with conventional agents at equivalent doses.

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.