Masafumi Kidoh, Abstract Co-Author: Nothing to Disclose

Takeshi Nakaura MD, Abstract Co-Author: Nothing to Disclose

Yasuhiko Iryo, Presenter: Nothing to Disclose

Toshinori Hirai MD, Abstract Co-Author: Nothing to Disclose

Kazunori Harada, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Consultant, DAIICHI SANKYO Group

Shinichi Nakamura MD, Abstract Co-Author: Nothing to Disclose

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

There is still no consensus regarding the optimal method for diagnosing the dissection of intracranial arteries with MRI. Previous reports suggested that the criteria of increase in the external diameter of the artery and narrowing of the lumen offer high diagnostic accuracy. We hypothesized that the 3D time-of-flight (TOF) and True fast imaging with steady-state precession (true-FISP) fusion imaging would be sufficient to confidently confirm or exclude vertebral artery dissection (VAD). The purpose of this study was to compare the accuracy of lesion detection and the diagnostic confidence of VAD between TOF images alone and fused TOF and true-FISP images.

This prospective study received institutional review board approval; prior informed consent to participate was obtained from all patients. Fifty patients were studied: 17 had VAD, and 33 had vertebral artery hypoplasia. The imaging parameters on a 1.5T MR scanner were: TOF: 18/2.84 (TR/TE); flip angle, 20°; section thickness, 0.77 mm; unenhanced true-FISP: 6.82/3.41 (TR/TE); flip angle, 70°; section thickness, 0.7 mm. Fusion images of the vertebral artery were reconstructed using a workstation. A receiver operating characteristic (ROC) analysis was conducted with a continuous rating scale from 1 to 100 to compare observer performance in the detection of VAD. Five radiologists participated in the observer performance test, and their performances with TOF images were compared with those using fused images. The observers first analyzed only TOF images and then analyzed two separate sets of TOF and fused images. The images were presented in random order at each case. The jackknife method was applied to find any significant differences among the methods and readers.

The five observers found the mean area under the best-fit ROC curve between TOF images alone and fused TOF images were 0.74±0.04 and 0.96±0.03, and the difference was significant (p<0.05).

The display of fusion images significantly improved the diagnostic performance of radiologists in the detection of VAD. Fused images made it possible to precisely assess the relationship between the inner and outer contours of the vessels.

The fused images of TOF and true-FISP can improve radiologists’ performance in detecting vertebral artery dissection. Fused images therefore make it possible to clearly visualize the vertebral artery.

Kidoh, M, Nakaura, T, Iryo, Y, Hirai, T, Harada, K, Yamashita, Y, Nakamura, S, Oda, S, A Simple and Useful MRI Fusion Technique for the Diagnosis of Vertebral Artery Dissection.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12036488.html