| Background:Magnetic resonance angiography (MRA) is an important technology of intracranial aneurysm screening. It is a non-invasive technique without intravenous administration and free of radiation. The sensitivity of MRA for detecting intracranial aneurysm was inferior to that of CTA and DSA in the past, because of low magnetic field strength and poor image quality. With the advance of 3 tesla MR scanner and the development of new vessel wall image technologies, MRI plays a more valuable role in assessing aneurysm morphology and rupture risk.Purpose:First, to compare MRA at 3 tesla and digital subtraction angiography (DSA) for measurement of aneurysm neck, diameter and height. Second, to assess aneurysmal wall thickness on high resolution images, and to investigate aneurysmal wall enhancement after gadolinium injection, and finally compare MR images with surgical findings.Methods:In the first session,16 patients underwent DSA and MRA test, the morphology parameters like aneurysmal neck, diameter and height were recorded from three dimensional aneurysm images. Parameters were analyzed with WilCoxon test for significance and Spearman test for rank correlation. In the second session, motion sensitized driven equilibrium (MSDE) sequence and contrast enhanced MSDE were applied to all patients. We evaluated aneurysmal wall of each aneurysm on MSDE and CE MSDE, and wall enhancement were compared between postcontrast and precontrast MSDE images. We classified the aneurysmal wall into three grades: grade 1(more than 60% aneurysmal wall were identified), grade 2 (30%-60%aneurysmal wall were identified) and grade 3 (less than 30% aneurysmal wall were identified). Wall enhancement results were also classified into three groups as "Strong enhancement," "Faint enhancement," and "No enhancement." 12 of 16 patients were underwent surgery, preoperative MR imaging findings were compared to surgical findings. The results were classified as follows:as expected, capable of expectation, and different from expectation.Results:In the first session, no statistically significant differences were found between mean values in MRA and DSA for aneurysmal neck (8.93±4.72mm vs. 9.29±4.04mm, p=0.234, r=0.968), diameter (12.91±6.83mm vs.12.65±6.86mm, p=0.379, r=0.933) and height (13.86±0.96mm vs.14.23±0.95mm, p=0.14, r=0.499). In the second session, on MSDE images grade 1 aneurysmal wall was identified in 2 cases, grade 2 were identified in 8 cases and grade 3 in 6 cases, while on CE MSDE images, grade 1 were found in 12 cases, grade 2 in 3 cases and grade 3 in 3 cases. "Strong enhancement" of aneurysmal wall were identified in 2 cases, "faint enhancement" in 11 cases and "no enhancement" in 3 cases. We predicted surgical findings on preoperative MR imaging in 12 of the 16 patients who underwent craniotomy,7 as expected,3 were capable of expectation and 2 were different from expectation.Conclusions:MRA at 3T is a very effective tool to assess aneurysm morphology. High resolution MSDE images and CE MSDE images provide significant aneurysmal wall information and contribute to making surgical plan and evaluating the risk of aneurysm rupture. |
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