Comparison of Time-Resolved and First-Pass Contrast-Enhanced MR Angiography in Pretherapeutic Evaluation of Spinal Dural Arteriovenous Fistulas

Usefulness of time-resolved MR angiography in spinal dural arteriovenous fistula (SDAVF)-a systematic review and meta-analysis

Spinal dural arteriovenous fistulas (SDAVFs) constitute the most common type of spinal vascular malformations. Their diagnosis requires spinal digital subtraction angiography (DSA), which is time-consuming, requires catheterizing many vessels, and exposes patient to a high radiation and contrast doses. This study aims to evaluate the usefulness of time-resolved MR angiography (TR-MRA) in SDAVF diagnosis. We performed a systematic review of the PubMed and EMBASE databases followed by a meta-analysis. TR-MRA was an index test, and spinal DSA was a reference. Of the initial 324 records, we included 4 studies describing 71 patients with SDAVFs. In 42 cases, TR-MRA was true positive, and in 21 cases, it was true negative. We found 7 false-positive cases and 1 false negative. TR-MRA allowed for shunt level identification in 39 cases. Of these, the predicted level was correct in 23 cases (59%), to within 1 level in 38 cases (97.4%) and to within 2 levels in 39 cases (100%). The diagnostic odds ratio was 72.73 (95% CI [10.30; 513.35]), z = 4.30, p value < 0.0001. The pooled sensitivity was 0.98 (95% CI [0.64; 1.00]), and the pooled specificity was 0.79 (95% CI [0.10; 0.99]). The AUC of the SROC curve was 0.9. TR-MRA may serve as a preliminary study to detect SDAVFs and localize the shunt level with sensitivity and specificity as high as 98% and 79%, respectively. Unless the TR-MRA result is unequivocal, it should be followed by a limited spinal DSA.

High diagnostic performance of time-resolved MR angiography in spinal arteriovenous shunts

BACKGROUND AND PURPOSE

In comparison with the limited efficacy of conventional MR imaging and the invasiveness of catheter-based digital subtraction angiography (DSA), time-resolved MR angiography (TR-MRA) has been proposed as a promising examination for early diagnosis of spinal arteriovenous shunts (SAVSs). This paper aims to investigate the diagnostic performance of TR-MRA with scan parameters optimized for SAVSs evaluation in a large number of patients.

METHODS

One hundred patients with suspected SAVSs were enrolled. Each patient underwent preoperative TR-MRA with optimized scan parameters followed by DSA. The presence or absence of SAVS, the types and the angioarchitecture of SAVSs in the TR-MRA images were diagnostically analyzed.

RESULTS

Among the final 97 patients, 80 cases (82.5 %) were diagnosed and classified by TR-MRA as spinal cord arteriovenous shunts (SCAVSs; n = 22), spinal dural arteriovenous shunts (SDAVSs; n = 48), and spinal extradural arteriovenous shunts (SEDAVSs; n = 10). The agreement for classifying SAVSs between TR-MRA and DSA was excellent (κ = 0.91). The sensitivity, specificity, PPV, NPV, and accuracy of TR-MRA for the diagnosis of SAVSs were 100 % (95 % CI, 94.3-100.0 %), 76.5 % (95 % CI, 49.8-92.2 %), 95.2 % (95 % CI, 87.6-98.5 %), 100 % (95 % CI, 71.7-100.0 %), and 95.9 % (95 % CI, 89.9-98.4 %). The accuracy rates of TR-MRA for the detection of feeding arteries were 75.9 %, 91.7 %, and 80.0 % for SCAVSs, SDAVSs, and SEDAVSs respectively.

CONCLUSION

Time-resolved MR angiography showed excellent diagnostic performance for SAVSs screening. Additionally, this method can classify SAVSs and identify feeding arteries in SDAVSs with high diagnostic accuracy.

Arteriovenous malformations of the filum terminale: clinical characteristics, angioarchitecture, and management of a rare spinal vascular pathology

OBJECTIVE

The goal of this study was to describe clinical and neuroradiological features of arteriovenous malformations of the filum terminale (FT AVMs) and to present the authors’ diagnostic and therapeutic management in this rare disease.

METHODS

The presented cases were retrieved from a retrospectively collected database of all spinal vascular malformations treated between June 1992 and December 2021 at the Rheinisch-Westfälische Technische Hochschule (RWTH) University Hospital Aachen. Pretreatment and follow-up clinical and neuroradiological data were analyzed for this study.

RESULTS

Data in 15 patients with FT AVM with a mean age of 60 years were included, with an overall incidence of FT AVM of 19% among all spinal AVMs in our cohort. Twelve of 15 (80%) patients were men. Nonspecific but typical clinical and MR findings of thoracolumbar congestive myelopathy were found in all patients. Spinal MR angiography, performed in 10 patients, identified in all cases the arterialized FT vein as well as a lumbar/lumbosacral location of an AV shunt. Digital subtraction angiography (DSA) showed an arterial supply solely via the FT artery in 12/15 (80%) patients and via an additional feeder from the lumbosacral region in the other 3/15 (20%) patients. All patients were treated surgically. During 1-year follow-up, 2 patients presented with recurrent FT AVM due to further arterial supply from the lumbosacral region, and were treated surgically. Neurological status was improved in all patients within the 1-year follow-up, with marginal further changes during long-term follow-up.

CONCLUSIONS

Congestive myelopathy is the major pathological mechanism of symptoms in these patients, with no evidence for intradural bleeding. Missing the presence of possible multiple arterial supply of FT AVM during DSA may result in misdiagnosis and/or insufficient treatment. Due to the frequently prolonged course of FT artery, resection of the FT AVM may be a favorable treatment modality in comparison with endovascular treatment. Follow-up examinations are obligatory within the first 3 years after treatment, and further MR angiography and DSA examinations are indicated if congestive myelopathy persists.

Time-Resolved Magnetic Resonance Angiography for Follow-Up of Treated Dural and Epidural Spinal Arteriovenous Fistula

BACKGROUND

 Spinal arteriovenous fistulas (AVFs) are uncommon vascular malformations of spinal dural and epidural vessels. Actually digital subtraction angiography (DSA) is the gold standard for diagnosis and follow-up. The aim of this study is to demonstrate the validity of the multiphasic magnetic resonance angiography (MRA) to identify recurrent/residual AVFs or their correct surgical and/or endovascular closure.

METHODS

 A retrospective cases series with perimedullary venous plexus congestion due to spinal dural or epidural AVF was performed at our center from April 2014 to September 2019. After 1 month from treatment, the patients were subjected to time-resolved MRA and DSA to demonstrate recurrence or correct closure of AVFs.

RESULTS

 We collected a series of 26 matched time-resolved MRA and DSA in 20 patients who underwent an endovascular and/or surgical procedure. In our series, we reported five cases of recurrence. Time-resolved MRA detected six cases of recurrence, with 100% sensitivity and 95% specificity (p < 0.001). We used DSA as the standard reference.

CONCLUSION

 Time-resolved MRA is a valid tool in posttreatment follow-up to detect recurrent or residual AVFs. It has high sensitivity and specificity and may replace DSA.

Spinal Vascular Shunts: A Patterned Approach

Spinal vascular shunts, including fistulas and malformations, are rare and complex vascular lesions for which multiple classification schemes have been proposed. The most widely adopted scheme consists of 4 types: type I, dural AVFs; type II, intramedullary glomus AVMs; type III, juvenile/metameric AVMs; and type IV, intradural perimedullary AVFs. MR imaging and angiography techniques permit detailed assessment of spinal arteriovenous shunts, though DSA is the criterion standard for delineating vascular anatomy and treatment planning. Diagnosis is almost exclusively based on imaging, and features often mimic more common pathologies. The radiologist's recognition of spinal vascular shunts may improve outcomes because patients may benefit from early intervention.

Paralysis After Lumbar Interlaminar Epidural Steroid Injection in the Absence of Hematoma: A Case of Congestive Myelopathy Due to Spinal Dural Arteriovenous Fistula and a Review of the Literature

Paraplegia after interlaminar epidural steroid injection is a rare event and has typically been described after epidural hematoma or direct spinal cord injury. We present a case of an 87-yr-old man who experienced transient lower limb weakness after a lumbar interlaminar epidural steroid injection due to an alternative cause, congestive myelopathy related to an underlying vascular malformation, namely, a spinal dural arteriovenous fistula. This is a poorly recognized and potentially treatable cause of progressive myelopathy. We present this case and review the literature on paraplegia after epidural steroid injection due to spinal dural arteriovenous fistula. Notably, this case of paralysis occurred in association with the lowest volume of epidural injectate reported in the literature to date (4 ml); importantly, this volume is consistent with the current clinical practice guideline standards for the safe performance of interlaminar epidural steroid injections. Physicians should be aware of this potential complication of epidural steroid injection and remain vigilant for the possibility after a procedure, even when performed according to current practice standards.

Transarterial CT angiography for surgical planning of spinal dural arteriovenous fistula

OBJECTIVE

We report a novel method to provide excellent anatomical depiction of a dural arteriovenous fistula (dAVF) for surgical planning.

METHODS

A 78-year-old female presented with progressive back pain, deteriorating mobility and urinary incontinence with a background of obesity and severe osteoarthritis. Initial MRI suspected dAVF and subsequent spinal angiography encountered an extremely tortuous and arteriosclerotic aorta, hence catheterisation of the segmental-intercostal and lumbar vessels proved challenging. Contrast injection into the aortic arch via a pigtail catheter for arterial-phase CT angiogram of the descending aorta was performed.

RESULTS

This modality of imaging delineated the dAVF showing extensive involvement of the whole spine accounting for the patient's symptoms. Furthermore this allowed characterisation of bony anatomy in relation to the fistula facilitating precise surgical approach. The dAVF was successfully disconnected through a localised laminectomy centred over the lesion.

CONCLUSION

This specific technique for dAVF characterisation has not been previously reported, although trans-venous angiography has been used to some effect. In view of diagnostic and therapeutic technical difficulties that are often faced in such patients, this technique may be a useful alternative that is not only helpful in accurate diagnosis but helps in providing an invaluable guide for the surgical approach.

ADVANCES IN KNOWLEDGE

This case highlights the difficulties that one may be faced within cases of tortuous vasculature and the obese patient population. With this in mind we demonstrate how a unique hybridised technique may provide valuable alternative to the neurosciences team should such a future scenario arise.

Long-term surgical outcomes of patients with delayed diagnosis of spinal dural arteriovenous fistula

Spinal dural arteriovenous fistula (dAVF) is an extremely rare vascular entity that is usually misdiagnosed. We sought to determine the long-term clinical outcomes of patients undergoing microsurgical treatment for delayed diagnosis of spinal dAVF. This retrospective study identified patients with delayed diagnosed spinal dAVF at our institution from 2009 to 2018. Patients' data, including demographics, imaging, and follow-up data, were evaluated. This cohort included 65 consecutive patients with 68 dAVFs and a male-to-female ratio of 4:1 and a mean age of 53.5 ± 13.7 years. The presenting symptoms consisted of limb weakness (n = 42, 64.6%), paraparesis (n = 34, 52.3%), sphincter disturbances (n = 8, 12.3%), and pain (n = 13, 20.0%). The proportion of patients with each symptom significantly increased and patients experienced increased disability when the diagnosis was finalized. The mean length of delay of diagnosis was 20.7 ± 30.0 months. Surgery resulted in complete occlusion of the fistula on the first attempt in all patients. Three patients developed recurrent fistulas, and three died in the follow-up period. Improved motor function was achieved in 38 patients (59.5%). Other symptoms, such as sensory disorders, sphincter dysfunction, and pain, improved by 37.3%, 32.3%, and 66.7%, respectively. Patients with spinal dAVF usually exhibit progressive ascending myelopathy and often remain misdiagnosed for months to years. Some patients' increased disability cannot be reversed through surgery.

Comparative Analysis of Volumetric High-Resolution Heavily T2-Weighted MRI and Time-Resolved Contrast-Enhanced MRA in the Evaluation of Spinal Vascular Malformations

BACKGROUND AND PURPOSE

Volumetric high-resolution heavily T2-weighted imaging or time-resolved contrast-enhanced MRA is used in the detection and characterization of spinal vascular malformations, though inherent trade-offs can affect their overall sensitivity and accuracy. We compared the efficacy of volumetric high-resolution heavily T2-weighted and time-resolved contrast-enhanced images in spinal vascular malformation diagnosis and feeder characterization and assessed whether a combined evaluation improved the overall accuracy of diagnosis.

MATERIALS AND METHODS

Twenty-eight patients with spinal vascular malformations (spinal dural arteriovenous fistula, spinal cord arteriovenous malformation, and perimedullary arteriovenous fistula) were prospectively enrolled. MR images were separately analyzed by 2 neuroradiologists blinded to the final diagnosis.

RESULTS

Both sequences demonstrated 100% sensitivity and 93.5% accuracy for the detection of spinal vascular malformations. Volumetric high-resolution heavily T2-weighted imaging was superior to time-resolved contrast-enhanced MR imaging for identification of spinal cord arteriovenous malformations (100% versus 90% sensitivity and 96.7% versus 93.5% accuracy), however, for the diagnosis of perimedullary arteriovenous fistula, time resolved contrast enhanced MRI was found to perform better than the volumetric T2 sequence (80% versus 60% sensitivity and 96.7% versus 93.5% accuracy). Both sequences showed equal sensitivity (100%) and accuracy (87%) for spinal dural arteriovenous fistulas. Combined evaluation improved the overall accuracy across all types of spinal vascular malformation. Volumetric high-resolution heavily T2-weighted imaging was superior or equal to time-resolved contrast-enhanced MR imaging for feeder identification of spinal dural arteriovenous fistulas for both observers (90.9% and 72.7% versus 72.7%), which improved to 90.9% when the sequences were combined. Time-resolved contrast-enhanced MR imaging performed better for major and total feeder identification of spinal cord arteriovenous malformation (80% versus 60%) and perimedullary arteriovenous fistula (80% versus 60%-80%).

CONCLUSIONS

Combined volumetric high-resolution heavily T2-weighted imaging and time-resolved contrast-enhanced MR imaging can improve the sensitivity and accuracy of spinal vascular malformation diagnosis, classification, and feeder characterization.

Volumetric T2-weighted MRI improves the diagnostic accuracy of spinal vascular malformations: comparative analysis with a conventional MR study

Background

To date, very little study of the importance of a volumetric T2-weighted MR sequence in the evaluation of spinal vascular malformations (SVMs) has been carried out.

Objective

To determine the utility and accuracy of a volumetric T2 MR sequence compared with conventional T2 in the diagnosis of SVMs.

Methods

Retrospective analysis of all patients who underwent spinal DSA for suspected SVMs was conducted. Conventional T2 and volumetric T2 MR images were analysed for the presence of flow voids and parenchymal changes, and SVMs were characterized. The sensitivity, specificity, and overall diagnostic accuracy of these MRI diagnoses were calculated.

Results

Of 89 subjects included in the final analysis, 70 patients had angiographically proved SVMs (38 patients with spinal cord arteriovenous malformations [SCAVM—intramedullary or perimedullary] and 32 cases of spinal dural arteriovenous fistula (SDAVF)) and the remaining 19 subjects were normal. The sensitivity and specificity for identification of SVMs were 98.1% and 90% for volumetric T2 sequences, compared with 82.8% and 89.4% for conventional T2 MRI, respectively. For characterization of spinal vascular lesions, volumetric MRI showed high sensitivity, specificity, and accuracy for SDAVF (100%, 90%, 97%, respectively) compared with conventional T2 MRI (71.8%, 89%, 79%, respectively). The positive likelihood ratio was high and negative likelihood ratio was zero for volumetric MRI evaluation of SDAVF, while these ratios were comparable between the two sequences for SCAVM.

Conclusion

Volumetric T2 MRI is highly sensitive for the detection of SVMs, especially for SDAVF. Volumetric T2 MRI could be introduced into routine clinical practice in the screening of suspected SVMs.

Dilated Vein of the Filum Terminale on MRI: A Marker for Deep Lumbar and Sacral Dural and Epidural Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Conventional MR imaging can provide important clues regarding the location of a spinal vascular malformation. We hypothesized that a dilated vein of the filum terminale, identified as a curvilinear flow void on T2WI, could be an imaging marker for a lower lumbar (L3-L5) or sacral fistula.

MATERIALS AND METHODS

We retrospectively identified all spinal dural and spinal epidural arteriovenous fistulas from 2 large tertiary referral centers from 2005 to 2018. All patients had a lumbar spinal MR imaging and a conventional spinal angiography. Images were reviewed by 2 neuroradiologists who categorized the level of the arterial feeder to the fistula and the presence or absence of a dilated vein of the filum terminale on T2WI and T1 postcontrast images. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula.

RESULTS

One hundred sixty-two patients were included. An enlarged filum terminale vein was identified in 39 patients. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of a dilated filum terminale vein for a deep lumbar or sacral fistula were 86%, 98.3%, 94.9%, and 95.1%, respectively.

CONCLUSIONS

The presence of a dilated vein of the filum terminale can accurately localize a spinal dural arteriovenous fistula/spinal epidural arteriovenous fistula to the lower lumbar or sacral spine in patients being evaluated for such lesions. This finding can be used to facilitate both noninvasive and conventional spinal angiography.

Spinal dural arteriovenous fistulas: the most frequent vascular malformations of the spinal cord

Spinal dural arteriovenous fistulas are produced by direct communication between the arterial and venous systems of the spinal cord, causing hypertension in the latter with spinal cord dysfunction. It is a rare pathology with unknown etiology and non-specific clinical symptoms that usually results in a delayed diagnosis. Often radiologists are the first to guide the disease towards an adequate diagnosis. Characteristic findings can be seen through MR or MR angiography, and may even locate the fistula in a high percentage of cases, although the pathology must be confirmed by spinal angiography. There are two treatment modalities: endovascular and surgical therapy. Endovascular treatment has improved in recent years with the advantages of a less invasive approach and is therefore usually chosen as primary therapy. In this article we review the main clinical manifestations, imaging findings and treatment of this pathology.