Detection of residual brain arteriovenous malformations after radiosurgery: diagnostic accuracy of contrast-enhanced four-dimensional MR angiography at 3.0 T

Abstract

Objective: To evaluate the diagnostic accuracy of four-dimensional MR angiography (4D-MRA) at 3.0 T for detecting residual arteriovenous malformations (AVMs) after Gamma Knife j (Elekta Instrument AB, Stockholm, Sweden) radiosurgery (GKRS). Methods: We assessed 36 angiographically confirmed AVMs in 36 patients who had been treated with GKRS. 4D-MRA was performed after GKRS and the time intervals were 39.4¡26.0 months [mean ¡ standard deviation (SD)]. 4D-MRA was obtained at 3.0 T after contrast injection, with a measured voxel size of 16161 mm and a temporal resolution of 1.1 s (13 patients) or a voxel size of 16162 mm and a temporal resolution of 0.98 s (23 patients). X-ray angiography was performed as the standard reference within 53¡47 days (mean ¡ SD) after MRA. To determine a residual AVM, the 4D-MRA results were independently reviewed by two readers blinded to the X-ray angiography results. We evaluated diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 4D-MRA for detection of a residual AVM. Results: A residual AVM was identified in 13 patients (13/36, 36%) on X-ray angiography. According to Readers 1 and 2, 4D-MRA had a sensitivity of 79.6% and 64.3%, a specificity of 90.9% and 100%, a PPV of 84.6% and 100% and an NPV of 90% and 81.5%, respectively, and a diagnostic accuracy of 86.1% for Readers 1 and 2, for detecting residual AVMs after GKRS. Conclusion: The diagnostic accuracy of 4D-MRA at 3.0 T seems high, but there is still the possibility of further improving the spatiotemporal resolution of this technique.

Value of 4D MR Angiography at 3T Compared with DSA for the Follow-Up of Treated Brain Arteriovenous Malformation

“…In our study, the proportion of residual bAVM detected with DSA was higher; 18 of 37 (48.6%), of which 12 of 18 (66.7%) were correctly depicted by 4D-MRA. Our results are consistent with the study of Lim et al, 22 which focused on the follow-up after radiosurgery. However, this study, compared with the present study, had the limitation of a large delay (up to 6 months) between the realization of 4D-MRA and DSA images.…”

“…The excellent agreement ( 1.00, 95% CI 1.00 -1.00) for patients treated after radiosurgery could compete with DSA for the follow-up of these patients. These results are consistent with the study of Lim et al, 22 which focused on the diagnostic accuracy of 4D-MRA after radiosurgery and found a diagnostic accuracy of 86.1%, with a sensitivity of 79.6% and 64.3% (reader 1 and 2), a specificity of 90.9% and 100%, a positive predictive value of 84.6% and 100%, and a negative predictive value of 90% and 81.5%. Furthermore, even if 4D-MRA cannot depict all the residual bAVM, its very high sensitivity and positive predictive value make it a very reliable test in case of positivity.…”

“…However, this study, compared with the present study, had the limitation of a large delay (up to 6 months) between the realization of 4D-MRA and DSA images. In contrast to the absence of false-positives in our study, Lim et al 22 reported 1 in their series where a normal vein was interpreted as pathologic. Indeed, sometimes it is difficult to differentiate if a vein is normal or pathologic.…”

“…[17][18][19][20] The value of 4D-MRA for the follow-up of patients with a treated bAVM has been rarely evaluated. 21,22 The purpose of this study was to evaluate the performance of 4D-MRA at 3T for the follow-up of patients with a treated bAVM. In other words, this study will try to answer the 2 following questions: is 4D-MRA enough to assert the cure?…”

Are Dynamic Arterial Spin-Labeling MRA and Time-Resolved Contrast-Enhanced MRA Suited for Confirmation of Obliteration following Gamma Knife Radiosurgery of Brain Arteriovenous Malformations?

“…The potential to improve follow-up procedures after GKR using less invasive and radiation-free imaging methods has been described elsewhere, and important attempts have been made using MRA as an alternative to DSA. 4,5,9,10 Multiple studies have concluded that individually, TOF angiography and time-resolved contrast-enhanced MRA (CE-MRA) have good diagnostic accuracy, which supports their addition to the standard follow-up protocols. However, due to their limited sensitivity and specificity, it is still recommended that DSA be performed to confirm AVM obliteration.…”