Advanced noninvasive imaging of spinal vascular malformations

MR Imaging of Spinal Vascular Lesions

Spinal vascular lesions are an uncommon but important etiology for myelopathy. A high index of suspicion and appropriate protocol development are critical to correctly diagnose and direct management of these lesions. Contrast enhanced MR angiography should be considered for characterization of these lesions following anatomic image acquisition. When reporting on these cases, the presence of intramedullary spinal cord edema and blood products as well as potential arterial supply and venous drainage should be included.

Dual-Source Computed Tomography Angiography versus Time-Resolved Contrast-Enhanced Magnetic Resonance Angiography for Diagnosis of Spinal Vascular Malformations: A Retrospective Study

OBJECTIVE

To investigate the performance of time-resolved angiography with stochastic trajectories (TWIST-MRA) and dual-source CT angiography (CTA), applied independently and in combination, for preoperative assessment of spinal vascular malformation (SVM).

METHODS

This retrospective study included 77 patients with suspected SVM who underwent TWIST-MRA, CTA, and digital subtraction angiography between September 2019 and December 2022. Precision recall curve analysis was used to assess diagnostic performance. The feeding artery and fistula location were evaluated using radiologist confidence level by CTA and TWIST-MRA.

RESULTS

Among the 77 patients, 71 had digital subtraction angiography-confirmed SVM (cervical, n = 7; thoracolumbar, n = 60; deep lumbosacral, n = 4) and 6 did not have SVM. Both TWIST-MRA and CTA showed excellent accuracy (96.1% vs. 94.8%) and sensitivity (98.6% vs. 97.2%) for diagnosis of SVM subtypes. TWIST-MRA performed slightly better than CTA in identifying the feeding artery and fistula (area under the curve-precision recall, 0.958 vs. 0.944); however, sensitivity was not statistically different (P = 0.512). Among SVM patients, the radiologist confidence levels in identifying feeding artery and fistula of SVMs were significantly higher with CTA+TWIST-MRA than with TWIST-MRA alone (P = 0.007). The radiologist confidence levels were significantly higher with CTA alone and CTA+TWIST-MRA compared to TWIST-MRA alone for fistula identification of cervical and deep lumbosacral SVMs (P < 0.001).

CONCLUSIONS

Both TWIST-MRA and CTA are reliable for diagnosing SVM and localizing the feeding artery and fistula. While TWIST-MRA remains the primary technique, the addition of CTA can improve diagnostic confidence. CTA may be considered as an alternative to TWIST-MRA for SVMs in the cervical and lumbosacral regions.

Neurologic pathologies of the vertebral spine

At some institutions, musculoskeletal and general radiologists rather than neuroradiologists are responsible for reading magnetic resonance imaging (MRI) of the spine. However, neurological findings, especially intrathecal ones, can be challenging. Intrathecal neurological findings in the spine can be classified by location (epidural, intradural extramedullary, and intramedullary) or etiology (tumor, infection, inflammatory, congenital). In this paper, we provide a succinct review of the intrathecal neurological findings that can be seen on MRI of the spine, primarily by location and secondarily by etiology, in order that this may serve as a helpful guide for musculoskeletal and general radiologists when encountering intrathecal neurological pathologies.

Angiographic challenges of spinal dural and epidural arteriovenous fistulas: report on 45 cases

PURPOSE

The localization of the fistula level in spinal dural arteriovenous fistulas (dAVFs) and epidural arteriovenous fistulas (edAVFs) remains a diagnostic challenge.

METHODS

Consecutive patients with spinal dAVFs and edAVFs in the thoracic, lumbar, and sacral regions were included. The primary endpoint was to describe the characteristics of patients who required angiography with multiple catheterizations of segmental arteries (10 or more).

RESULTS

Forty-five patients (median age 69 years; male 89%; dAVFs, n = 31; edAVFs, n = 14) were included. Spinal dAVFs commonly developed in the thoracic region and edAVFs in the lumbosacral region. Fistulas were predicted at the correct level or plus/minus 2 level in less invasive examinations using multi-detector CT angiography (n = 28/36, 78%) and/or contrast-enhanced MR angiography (n = 9/14, 64%). We encountered diagnostic challenges in the localization of fistulas in 6 patients. They underwent angiography a median of 2 times. In each patient, spinal levels were examined at a median of 25 levels with a median radiation exposure of 3971 mGy and 257 ml of contrast. Fistulas were finally localized at the high thoracic region (T4-6) in 3 patients, the sacral region (S1-2) in 2, and the lumbar region (L3) in 1. Four patients were diagnosed with edAVFs and 2 with dAVFs. The correlation coefficient between the fistula level and the rostral end of the intramedullary T2 high-signal intensity on MRI was interpreted as none.

CONCLUSION

In patients in whom less invasive examinations failed for fistula localization, high thoracic or sacral AVFs need to be considered.

Removal of Antiscatter Grids for Spinal Digital Subtraction Angiography: Dose Reduction without Loss of Diagnostic Value

Background Spinal digital subtraction angiography (DSA) exposes patients and operators to substantial amounts of radiation. Antiscatter grid (ASG) removal is used to decrease radiation exposure but may reduce image quality. Purpose To determine whether ASG removal during spinal DSA in adults reduces radiation dose while maintaining diagnostic image quality and whether dose reduction is related to body mass index (BMI). Materials and Methods This Health Insurance Portability and Accountability Act-compliant prospective study included adults undergoing spinal DSA between January and December 2016. Each procedure included an additional angiographic acquisition performed twice, once with and once without ASG, either documenting the artery of Adamkiewicz (no pathology group) or the condition leading to the procedure (pathology group). Dose differences between study acquisitions and the influence of BMI were evaluated via paired t test. Two neurointerventionalists blinded to acquisition protocols were asked to independently evaluate a sample of 40 study acquisitions (20 with ASG, 20 without ASG) from 20 randomly selected participants to (a) rate image quality, (b) categorize findings, and (c) determine whether images had been obtained with or without ASG. Percentage agreement on image quality, findings categorization, and ability to correctly identify the acquisition protocol was calculated for both readers. Results Fifty-three participants (mean age ± standard deviation, 51 years ± 15.2; 32 men) were evaluated. ASG removal reduced the mean dose per acquisition by approximately 33% (mean dose-area product and air kerma decreased from 202 to 135.6 µGy/m² and from 35.3 to 24 mGy, respectively; P < .001) independently of BMI (P = .3). Both readers evaluated all images (40 of 40) as being of diagnostic quality and correctly categorized findings in 19 of 20 (95%) cases. Overall percentage agreement for correct protocol identification was 60% (12 of 20) for grid-in and 45% (nine of 20) for grid-out images. Conclusion Antiscatter grid removal during spinal digital subtraction angiography decreased participants' radiation exposure while preserving diagnostic image quality. © RSNA, 2020.

Application of Multimodal Navigation together with Fluorescein Angiography in Microsurgical Treatment of Cerebral Arteriovenous Malformations

This study aimed to explore the clinical applications of multimodal navigation combined with indocyanine green (ICG) fluorescein angiography in microsurgical treatment of cerebral arteriovenous malformations (AVMs). We retrospectively collected 52 patients with AVMs. Assisted by anatomic image, we reestablished three-dimensional structure using preoperative functional magnetic resonance imaging (fMRI) and Diffusion tensor imaging (DTI). The operation for lesion resection was finished under the assistance of neuro-navigation. ICG fluorescein angiography was performed for 16 of the study subjects, meanwhile, FLOW800 was used to rebuild blood vessel color visual image. Brain angiography was performed 1 week after the operation to check residual malformations. The patients’ status was estimated by Modified Rankin Scale score. Of the AVMs, 92.3% (48/52) were totally removed, without severe side events. Among the patients, fluorescein angiography was carried out up to 58 times for 16 cases. All of these 16 cases were confirmed with malformations and 14 of them had draining vein. The total resection rate of these 16 cases reached 100%, and the occurrence rate of postoperative complications was not significantly increased. During the operation of lesion resection, the application of multimodal navigation could effectively protect functional cortex and conduction pathway.

Spinal angiolipomas: A puzzling case and review of a rare entity

Patients with spinal epidural abscesses (SEAs) may have a variable presentation. Such an infection has a typical appearance on magnetic resonance imaging (MRI) and enhances with gadolinium. We present a case that was a diagnostic challenge where pre- and intra-operative findings resulted in conflicting impressions. The mimicker was a spinal angiolipoma (SAL). The authors then provide a thorough review of this rare spinal neoplasm. A 55-year-old man presented with back pain, paresis, paresthesia, and urinary retention. MRI was indicative of a longitudinal epidural thoracic mass with a signal homogeneous to nearby fat, curvilinear vessels, and lack of enhancement. Although at emergent surgery, the lesion was found to contain abundant purulent material. Microbiology was positive for methicillin-resistant Staphylococcus aureus and consistent with SEA without evidence of neoplasia. While the imaging features were suggestive of an angiolipoma, the findings at surgery made SEA more likely, which were validated histopathologically. The diagnosis of SEA is often clear-cut, and the literature has reported only a few instances in which it masqueraded as another process such as lymphoma or myelitis. The case highlights SEA masquerading as an angiolipoma, and further demonstrates to clinicians that obtaining tissue diagnosis plays a crucial role diagnostically and therapeutically. SALs, on the other hand, are slow-growing tumors that can be infiltrating or noninfiltrating. They typically present with chronic symptoms and T1-MRI shows an inhomogeneous picture. Complete surgical excision is standard of care and patients tend to do well afterward.

Advances and innovations in brain arteriovenous malformation surgery

Arteriovenous malformations (AVMs) of the brain are very complex and intriguing pathologies. Since their initial description by Luschka and Virchow in the middle of the 19th century, multiple advances and innovations have revolutionized their management and surgical treatment. Here, we review the historical landmarks in the surgical treatment of AVMs and then illustrate the most recent and futuristic technologies aiming to improve outcomes in AVM surgeries. In particular, we examine potential advances in patient selection, imaging, surgical technique, neuroanesthesia, and postoperative neuro-rehabilitation and quantitative assessments. Finally, we illustrate how concurrent advances in radiosurgery and endovascular techniques might present new opportunities to treat AVMs more safely from a surgical perspective.

Three-dimensional angioarchitecture of spinal dural arteriovenous fistulas, with special reference to the intradural retrograde venous drainage system

Object

There have been significant advances in understanding the angioarchitecture of spinal dural arteriovenous fistulas (AVFs). However, the major intradural retrograde venous drainage system has not been investigated in detail, including the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater, which are the final targets of interruption in both microsurgical and endovascular treatments.

Methods

Between April 1984 and March 2011, 27 patients with 28 AVFs were treated for spinal dural AVFs at the authors' university hospital. The authors assessed vertebral levels of feeding arteries and dural AVFs by using conventional digital subtraction angiography. They also assessed 3D locations of the most proximal sites of intradural radiculomedullary veins and the 3D positional relationship between the major intradural retrograde venous drainage system and intradural neural structures, including the spinal cord, spinal nerves, and the artery of Adamkiewicz, by using operative video recordings plus 3D rotational angiography and/or 3D computer graphics. In addition, they statistically assessed the clinical results of 27 cases. Of these lesions, 23 were treated with open microsurgery and the rest were treated with endovascular methods.

Results

Feeding arteries consisted of T2–10 intercostal arteries with 19 lesions, T-12 subcostal arteries with 3 lesions, and L1–3 lumbar arteries with 6 lesions. The 3D locations of the targets of interruption (the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater) were identified at the dorsolateral portion of the dura mater adjacent to dorsal roots in all 19 thoracic lesions, whereas they were identified at the ventrolateral portion of the dura mater adjacent to ventral roots in 7 (78%) of 9 cases of conus medullaris/lumbar lesions (p < 0.001). The major intradural retrograde venous drainage system was located dorsal to the spinal cord in all 19 thoracic lesions, whereas it was located ventral to the spinal cord in 4 (44%) of 9 cases of conus/lumbar lesions (p = 0.006). In 3 (11%) of 27 cases, AVFs had a common origin of the artery of Adamkiewicz. In 2 lumbar lesions, the artery of Adamkiewicz ascended very close to the vein because of its ventral location. Although all lesions were successfully obliterated without major complications and both gait and micturition status significantly improved (p = 0.005 and p = 0.015, respectively), conus/lumbar lesions needed careful differential diagnosis from ventral intradural perimedullary AVFs, because the ventral location of these lesions contradicted the Spetzler classification system.

Conclusions

The angioarchitecture of spinal dural AVFs in the thoracic region is strikingly different from that in conus/lumbar regions with regard to the intradural retrograde venous drainage system. One should keep in mind that spinal dural AVFs are not always dorsal types, especially in conus/lumbar regions.

Absence of abnormal vessels in the subarachnoid space on conventional magnetic resonance imaging in patients with spinal dural arteriovenous fistulas

Spinal dural arteriovenous fistula (DAVF) is an uncommon condition that can be difficult to diagnose. This often results in misdiagnosis and treatment delay. Although conventional MRI plays an important role in the initial screening for the disease, the typical MRI findings may be absent. In this article, the authors present a series of 4 cases involving patients with angiographically proven spinal DAVFs who demonstrated cord T2 prolongation on conventional MRI but without abnormal subarachnoid flow voids or enhancement. These cases suggest that spinal DAVF cannot be excluded in symptomatic patients with cord edema based on conventional MRI findings alone. Dynamic Gd-enhanced MR angiography (MRA) was successful in demonstrating abnormal spinal vasculature in all 4 cases. This limited experience provides support for the role of spinal MRA in patients with abnormal cord signal and symptoms suggestive of DAVF even when typical MRI findings of a DAVF are absent.

Rotational angiography for diagnosis and surgical planning in the management of spinal vascular lesions

Object

The management of spinal vascular malformations has undergone significant evolution with the advent of advanced endovascular and angiographic technology. Three-dimensional rotational spinal angiography is an advanced tool that allows the surgeon to gain a better appreciation of the anatomy of these spinal vascular lesions and their relation to surrounding structures. This article describes the use of rotational angiography and 3D reconstructions in the diagnosis and management of spinal vascular malformations.

Methods

The authors present representative cases involving surgical treatment planning for spinal vascular malformations with focus on the utility and technique of rotational spinal angiography. They report the use of rotational spinal angiography for a heterogeneous collection of vascular pathological conditions.

Results

Eight patients underwent rotational spinal angiography in addition to digital subtraction angiography (DSA) for the diagnosis and characterization of various spinal vascular lesions. Postprocessed images were used to characterize the lesion in relation to surrounding bone and to enhance the surgeon's ability to precisely localize and obliterate the abnormality. The reconstructions provided superior anatomical detail compared with traditional DSA. No associated complications from the rotational angiography were noted, and there was no statistically significant difference in the amount of radiation exposure to patients undergoing rotational angiography relative to traditional angiography.

Conclusions

The use of rotational spinal angiography provides a rapid and powerful diagnostic tool, superior to conventional DSA in the diagnosis and preoperative planning of a variety of spinal vascular pathology. A more detailed understanding of the anatomy of such lesions provided by this technique may improve the safety of the surgical approach.

Time-resolved magnetic resonance angiography: evaluation of intrapulmonary circulation parameters in pulmonary arterial hypertension

PURPOSE

To determine whether pulmonary arterial and venous transit times measured by time-resolved magnetic resonance angiography (MRA) can be used as a diagnostic tool for pulmonary arterial hypertension (PAH).

MATERIALS AND METHODS

Twelve patients with confirmed PAH and 10 healthy volunteers were scanned with Institutional Review Board (IRB) approval. Time-resolved MRA and 2D phase contrast flow images of the pulmonary vasculature were acquired. Pulmonary arterial and venous transit times (PaTT and PvTT) and pulmonary valve flow (PVF) were obtained. Pulmonary arterial and pulmonary venous blood volumes (PaBV and PvBV) were calculated as the product of flow and transit time.

RESULTS

Patients with PAH showed statistically significant increases in PaTT and PvTT (P < 0.0004, P < 0.05, respectively) compared to controls. PaBV (165.2 ± 92.0 mL) was significantly higher in PAH subjects than controls (97.0 ± 47.1 mL) (P < 0.04), whereas PvBV (127.9 ± 148.9 mL) of PAH subjects had no significant increase from those of healthy controls (142.5 ± 104.1 mL) (P < 0.38).

CONCLUSION

Pulmonary arterial transit times measured using time-resolved MRA can be used as a simple, noninvasive metric for detection of altered hemodynamics in PAH.

Recovery from paraplegia after the treatment of spinal dural arteriovenous fistula: case report and review of the literature

BACKGROUND

Spinal dural arteriovenous fistula (SDAVF) is a rare and enigmatic disease. Functional outcome is particularly uncertain for the small group of patients that are unable to stand at the time of diagnosis (grade 5 gait disturbance on the Aminoff-Logue scale, ALS). The objective of this study is to examine the final functional outcome of patients with SDAVF in grade 5 gait ALS before treatment.

METHODS

We conducted a PubMed search using the keyword "spinal dural arteriovenous fistula." A review of the clinical series and single well-detailed case reports of SDAVF gathered 106 patients with grade 5 gait ALS on the initial examination. Additionally, we report the case of a 56-year-old man presenting acute paraplegia and urinary retention on admission who had complained of sporadic motor and sphincter disturbances for 1 year. Spine T2-weighted MR imaging showed a central hyperintensity within the spinal cord, and the angiography demonstrated a T-11 SDAVF. Interruption of the fistula was performed through an urgent one-level laminectomy.

RESULTS

Grade 5 gait ALS was present in 25% of the patients with SDAVF included in the clinical series. Latest follow-up showed that gait disturbance improved in 73% of patients after treatment, although less than 6% became grade 1 gait ALS. Micturition disturbances improved in 39%. Exploration of our patient showed improvement to grade 1 gait ALS 1 year after the surgical treatment.

CONCLUSION

Interruption of SDAVF in paraplegic patients may improve the final functional gait outcome in some cases. No complete recovery (grade 0 gait ALS) was achieved after treatment. Micturition disturbances had a worse prognosis than motor deficits.