Background: In ruptured aneurysms, vessel wall imaging (VWI) shows aneurysm wall enhancement, which may be caused by inflammation of the aneurysm wall. However, whether this inflammation is the cause or the result of aneurysm rupture remains unknown. In this study, we analyzed high-resolution VWI on posterior communicating artery (PComA) aneurysms, seeking to better understand aneurysm wall inflammation.
Hypothesis: Oculomotor nerve palsy (ONP) is a warning sign of PComA aneurysm rupture. ONP results from compression of the oculomotor nerve and indicates aneurysm enlargement. Thus, PComA aneurysms with ONP are about to rupture, which makes them perfect cases to research aneurysm wall inflammation. If the inflammation of the aneurysm wall is the cause of aneurysm rupture, VWI may capture images of aneurysm wall enhancement before it ruptures.
Methods: PComA aneurysm patients with ONP were examined using a Verio 3.0T scanner with a 12-channel head coil (Siemens Healthcare, Erlangen, Germany). Time-of-flight MRI angiography was performed to localize the aneurysm site. Then, a high-resolution T1-weighted black blood vessel wall sequence was obtained before and after intravenous administration of gadolinium. Each sequence was performed in the axial planes. Additional coronal planes or other planes were obtained if necessary. Patients with ruptured PComA aneurysms were also examined as a positive control, and patients with unruptured PComA aneurysms without ONP were examined as a negative control.
Results: Ten patients with PComA aneurysm were examined. VWI of 3 patients with ONP showed aneurysm wall enhancement. Of these 3 patients, 2 were with post-orbital pain, and VWI showed complete enhancement of the aneurysm wall. VWI showed partial enhancement of the aneurysm wall in the other one patient without post-orbital pain. In the positive control group, complete wall enhancement was seen in all 3 ruptured PComA aneurysms (2 with ONP, 1 without ONP). In the negative control group of 4 cases, no aneurysm wall enhancement was seen.
Conclusion: VWI demonstrated aneurysm wall enhancement in PComA aneurysms with ONP, which indicates that wall inflammation may occur before aneurysm rupture.