Diagnostic Accuracy of Non-Contrast-Enhanced Time-Resolved MR Angiography to Assess Angioarchitectural Classification Features of Brain Arteriovenous Malformations

Abstract

This study aims to assess the diagnostic accuracy of non-contrast-enhanced 4D MR angiography (NCE-4D-MRA) compared to contrast-enhanced 4D MR angiography (CE-4D-MRA) for the detection and angioarchitectural characterisation of brain arteriovenous malformations (bAVMs). Utilising a retrospective design, we examined 54 MRA pairs from 43 patients with bAVMs, using digital subtraction angiography (DSA) as the reference standard. Both NCE-4D-MRA and CE-4D-MRA were performed using a 3-T MR imaging system. The primary objectives were to evaluate the diagnostic performance of NCE-4D-MRA against CE-4D-MRA and DSA and to assess concordance between imaging modalities in grading bAVMs according to four main scales: Spetzler-Martin, Buffalo, AVM embocure score (AVMES), and R2eDAVM. Our results demonstrated that NCE-4D-MRA had a higher accuracy and specificity compared to CE-4D-MRA (0.85 vs. 0.83 and 95% vs. 85%, respectively) and similar agreement, with DSA detecting shunts in bAVMs or residuals. Concordance in grading bAVMs was substantial between NCE-4D-MRA and DSA, particularly for the Spetzler-Martin and Buffalo scales, with CE-4D-MRA showing slightly higher kappa values for interobserver agreement. The study highlights the potential of NCE-4D-MRA as a diagnostic tool for bAVMs, offering comparable accuracy to CE-4D-MRA while avoiding the risks associated with gadolinium-based contrast agents. The safety profile of imaging techniques is a significant concern in the long-term follow up of bAVMs, and further prospective research should focus on NCE-4D-MRA protocol improvement for clinical use.

Keywords: AVMES; R2DAVM; Spetzler–Martin; brain arteriovenous malformations; buffalo; contrast-enhanced MR angiography; non-contrast-enhanced MR angiography.

Figure 1

Magnetic resonance angiography of a thirty-five-year-old man with an untreated frontoparietal AVM, initially discovered on a haemorrhagic event. The anteroposterior maximal intensity projections of both 4D-MRA techniques studied are presented. The six most relevant of ten dynamic images of NCE-4D-MRA appear in (a–f), with a temporal resolution of 200 ms. Corresponding dynamic images of CE-4D-MRA appear in (g–l), with a temporal resolution of 1400 ms. The images reveal two arterial feeders from the left middle cerebral artery, a small nidus (<30 mm) in the postcentral gyrus, and a superficial veinous drainage in the superior sagittal sinus. The temporal resolution of NCE-4D-MRA allows for precision in the arterial analysis, but the loss of signal in the last scan times limits veinous characteristic descriptions.

Figure 2

Flow chart.

Figure 3

An illustration of a forty-year-old man with an unruptured and untreated brain arteriovenous malformation (bAVM). The anteroposterior (a) and lateral (b) maximal intensity projection (MIP) of a non-contrast-enhanced four-dimensional magnetic resonance angiography (NCE-4D-MRA) at the best nidus phase. The anteroposterior (c) and lateral (d) maximal intensity projection (MIP) of a contrast-enhanced four-dimensional magnetic resonance angiography (CE-4D-MRA) at the best nidus phase. The anteroposterior (e) and lateral (f) projections of a digital subtraction angiography (DSA) at the best nidus phase. The images show a bAVM in eloquence localisation (precentral gyrus in left frontal lobe), with a nidus size between 30 mm and 60 mm, six arterial feeders from the left anterior artery and left middle cerebral artery, and a superficial veinous drainage in the superior sagittal sinus. NCE-4D-MRA allows for precision about arterial feeders with a lack of signal on veinous drainage, while the temporal resolution of CE-4D-MRA does not disassociate arterial and venous phases as accurately as NCE-4D-MRA and DSA. DSA outperforms 4D-MRAs in an arterial feeder analysis.