Safety of diagnostic spinal angiography in children

Pediatric Interventional Neuroradiology: "How I Do It" v. I - Diagnostic Angiography

Pediatric neurointervention differs from the adult in several important respects. Here we describe a modern approach to readily acquire diagnostic quality images of children. Preparation, access, angiogragraphy and closure have evolved along with new knowledge and technology. This timely "how I do it" series addresses each topic utilizing literature review and our own experience over 35 years.

Preoperative spinal angiography decreases risk of spinal ischemia in pediatric posterior thoracic tumor resection

PURPOSE

Resection of pediatric posterior thoracic tumors (PTTs) can be complicated by Artery of Adamkiewicz (AKA) injury. Post-op spinal ischemia occurs in approx. 3.2% of patients, typically due to iatrogenic vascular injury. Pre-op angiography (PSA) may help to avoid this complication. Herein, we aim to evaluate outcomes after initiation of routine PSA prior to PTT resection.

METHODS

A single-institution retrospective review identified 25 children (< 18 years) treated for PTTs from 2009 to 2021. PTTs included: posterior mediastinum, paraspinal thorax and posterior chest wall tumors. PSA patients were compared to those without pre-operative angiography (NA). Demographics, perioperative and long-term outcomes and event-free survival (EFS) were assessed.

RESULTS

Prior to 2012, eleven patients were treated without PSA. However, the last developed post-operative paraplegia secondary to spinal ischemia. Since this event, PSA has become routine for all PTTs (n = 14) identifying six AKAs and nine accessory spinal arteries. Resection was performed in ten (90.1%) NA patients and eight (57.1%) PSA patients. Based on PSA findings, resection was not offered to six patients and planned partial resection was performed in three patients. Five PSA patients required radiation therapy for local control vs two NA patients. There were no differences in recurrence or overall EFS.

CONCLUSION

PSA aids in identifying patients with high-risk thoracic vascular anatomy and may prevent risk of post-operative paraplegia associated with PTT resection.

Interactive spinal computed tomography angiography-guided spinal digital subtraction angiography and embolization for thoracolumbar epidural arteriovenous fistulas: illustrative case

BACKGROUND

Spinal digital subtraction angiography (sDSA) is the gold standard for examining spinal arteriovenous fistulas; however, thorough sDSA evaluations of spinal arteriovenous fistulas require a long procedure, which may increase the radiation exposure time.

OBSERVATIONS

A 72-year-old man presented with progressive myelopathy due to a spinal epidural arteriovenous fistula. Spinal computed tomography angiography (sCTA) showed an epidural arteriovenous fistula fed by the left L3 segmental artery. To prepare for sDSA, the sCTA images were modified to mark the segmental artery bifurcations from T5 to L5 with multicolored markers. These modified sCTA images were loaded onto the multiwindow DSA display. The sCTA images were interactively modulated during sDSA. This sCTA-guided sDSA identified 18 segmental arteries within 47 minutes. The total radiation exposure was 1,292 mGy. Subsequently, transarterial embolization resolved the epidural arteriovenous fistula with clinical improvement.

LESSONS

Three-dimensional sCTA can provide detailed anatomical information before sDSA. Modified sCTA images with segmental artery bifurcation marking can provide interactive guidance on multipanel DSA displays. sCTA-guided sDSA is useful for accurate catheterization and reduction of procedure time.

Radiation Dose and Fluoroscopy Time of Diagnostic Angiography in Patients with Spinal Dural Arteriovenous Fistula

PURPOSE

Spinal dural arteriovenous fistulas (SDAVFs) represent the most common indication for a spinal angiography. The diagnostic reference level (DRL) for this specific endovascular procedure is still to be determined. This single-center study provides detailed dosimetrics of diagnostic spinal angiography performed in patients with SDAVFs.

METHODS

Retrospective analysis of all diagnostic spinal angiographies between December 2011 and January 2021. Only patients with an SDAVF who had baseline magnetic resonance angiography (MRA), diagnostic digital subtraction angiography (DSA), treatment and follow-up at this institution were included. Dose area product (DAP, Gy cm²) and fluoroscopy time were compared between preoperative and postoperative angiographies, according to SDAVF locations (common versus uncommon), MRA results at baseline (positive versus negative) and DSA protocols (low-dose, mixed-dose, normal-dose). The 75th percentile of the DAP distribution was used to define the local DRL.

RESULTS

A total of 62 spinal angiographies were performed in 25 patients with SDAVF. Preoperative angiographies (30/62, 48%) yielded a significantly higher DAP and longer fluoroscopy time when compared to postoperative angiographies (32/62, 53%) (p < 0.01). The local DRL was 329.41 Gy cm² for a nonspecific (n = 62), 395.59 Gy cm² for a preoperative and 138.6 Gy cm² for a postoperative spinal angiography. Preoperative angiography of uncommonly located SDAVFs yielded a significantly longer fluoroscopy time (p = 0.02). The MRA-based fistula detection had no significant impact on dosimetrics (p > 0.05). A low-dose protocol yielded a 61% reduction of DAP.

CONCLUSION

The results of the present study suggest novel DRLs for spinal angiography in patients with SDAVF. Dedicated low-dose protocols enable radiation dose optimization in these procedures.

Spinal vascular malformations: Angiographic evaluation and endovascular management

Spinal vascular malformations (SVM) are classified based on their location (intramedullary, perimedullary, radicular, extradural) and flow pattern (high-flow, low-flow, no arteriovenous shunt). High-flow SVMs are generally congenital lesions diagnosed in children and young patients without gender predominance. They present with hemodynamic disturbances, mass effect, or hemorrhages, but may also be discovered incidentally. Low-flow SVMs tend to be acquired lesions presenting in older men with progressive myelopathy caused by spinal venous hypertension. They are rarely associated with vascular syndromes but may accompany prothrombotic conditions. The sensitivity and specificity of conventional MRI are excellent for high-flow SVMs but poor for low-flow lesions, which are frequently diagnosed with extensive delays reducing the potential for favorable outcomes. The sensitivity of advanced MRI techniques remains unclear, notably for the detection of low-flow shunts without flow voids on conventional MRI. Catheter angiography remains the gold standard modality for the evaluation of the spinal vasculature and its disorders. SVMs can be treated by surgical or endovascular means. Initially plagued by high recurrence rates due to inadequate embolization material, endovascular techniques represent nowadays a valid alternative to surgery, thanks notably to the introduction of liquid embolic agents.