Akiyoshi Hamaguchi, Presenter: Nothing to Disclose

Noriyuki Fujima MD, Abstract Co-Author: Nothing to Disclose

Daisuke Yoshida, Abstract Co-Author: Nothing to Disclose

Naoko Hamaguchi, Abstract Co-Author: Nothing to Disclose

Syuichi Kodera MD, Abstract Co-Author: Nothing to Disclose

Cerebral ischemia secondary to vasospasm occurs postoperatively in 20%–30% subarachnoid hemorrhage patients. Digital subtraction angiography (DSA) is the gold standard for diagnosing cerebral vasospasm but it is invasive. Noninvasive auxiliary diagnosis by magnetic resonance angiography (MRA) has been attempted; however, subacute hemorrhage prevents the visualization of vasculature in postoperative subarachnoid hemorrhage (SAH). The subtraction process removed this hyperintensity. In this study, we compared subtraction MRA (SMRA) and conventional MRA (CMRA) with regard to diagnosis of vasospasm in patients with aneurysmal SAH.

From October 2009 to December 2010, 23 patients who underwent routine computed tomography (CT) and multidetector-row spiral CT angiography (MDCTA) for initial diagnosis of aneurysmal SAH were retrospectively analyzed. MRA was acquired by a spoiled gradient-echo imaging sequence with the following acquisition parameters: FOV = 200 mm2, matrix = 192 × 256 pixels, TR = 32 ms, TE = 6.9 ms, flip angle = 18°, BW = 19.23 kHz, slice thickness = 1.4 mm, NEX = 1, asset factor = 2, and acquisition time = 3 min 12 s. Arteries were assigned to 1 of 3 categories based on the degree of MRA appropriateness for diagnosis of vasospasm: 0, bad ... 2, good. Furthermore each artery was assigned to 1 of 4 categories based on the degree of vasospasm severity: 0, no spasm … 3, severe. The separation of severity against DSA was defined as subtracting DSA score from MRA score for vasospasm severity. CMRA and SMRA were compared for each arterial region by the two-sided Wilcoxon signed rank test for diagnosing vasospasms and separation of severity against DSA.

For diagnosis of cerebral vasospasm, CMRA and SMRA scores were 1.23 and 1.76, respectively, with regard to MRA appropriateness; SMRA scores were significantly higher than CMRA scores (p<0.05). For the separation of severity against DSA, CMRA and SMRA scores were 0.88 and 0.30, respectively; SMRA scores were significantly lower than CMRA scores (p<0.05).

This demonstrated that SMRA can diagnose vasospasm more accurately than CMRA. Furthermore, SMRA can help in exclusion of vasospasm in postoperative SAH, and SMRA can the decrease the use of MDCTA and DSA.

Subtraction MRA can improve diagnostic accuracy due to decrease in overestimation as compared with CMRA. 

Hamaguchi, A, Fujima, N, Yoshida, D, Hamaguchi, N, Kodera, S, Improvement of the Diagnostic Accuracy of MRA with Subtraction Technique in the Cerebral Vasospasm.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002034.html