Preoperative Digital Subtraction Angiography in Incidental Unruptured Intracranial Aneurysms : How Much is too Much?

Digital subtraction angiography (DSA) is deemed necessary to precisely visualize intracranial aneurysms and define individual treatment strategies. In patients with unruptured intracranial aneurysms (UIA) who were diagnosed by MRI, a four-vessel DSA is usually performed to detect additional aneurysms. This study aimed to evaluate whether the evaluation of all vessels beyond the aneurysm-harboring artery is really necessary.

Patients with an UIA that was detected on MRA (TOF/ceMRA) were prospectively included. All patients underwent a four-vessel DSA (including 3D-DSA) and two experienced neuroradiologists independently analyzed the MRI sequences before DSA. The number of aneurysms, size and anatomic localization were documented and correlated with the angiographic findings.

The DSA revealed a total of 134 aneurysms in 106 patients. Overall sensitivity and negative predictive value of MRA were 95.6% and 95.6%, respectively. In patients with multiple (≥2) aneurysms, 4 very small aneurysms <3 mm in the A2 segment, posterior communicating artery (PcomA), extradural internal carotid artery (ICA) were missed with MRI alone. In one patient with an ICA aneurysm, an additional small MCA bifurcation aneurysm was overlooked by MRA but detected by DSA. The periprocedural complication rate was 0.9%.

The rate of aneurysms that were detected by DSA but not by MRA was very low, thus potentially justifying visualization of the vessel harboring aneurysm alone; however, the four-vessel angiography detected further small aneurysms in patients with multiple aneurysms and therefore seems to be indicated in this specific subgroup. This approach has the potential to reduce the risk of complications, the intervention time and thus radiation exposure.