Shingo Kakeda MD, Presenter: Nothing to Disclose

Yukunori Korogi MD, Abstract Co-Author: Nothing to Disclose

Keita Watanabe, Abstract Co-Author: Nothing to Disclose

Johji Nishimura MD, Abstract Co-Author: Nothing to Disclose

Tetsuya Yoneda PhD, Abstract Co-Author: Research grant, Koninklijke Philips Electronics NV

Yasuhiro Hiai PhD, Abstract Co-Author: Nothing to Disclose

Toru Sato, Abstract Co-Author: Nothing to Disclose

Norihiro Ohnari, Abstract Co-Author: Nothing to Disclose

Although T2WI and T2*WI demonstrate the increased iron content of the substantia nigra (SN) in patients with Parkinson's disease (PD), it is difficult to apply this finding to the diagnosis of individual PD cases in clinical practice. Recently, we have developed new phase-weighted MR imaging, “Phase Difference Enhanced Imaging (PADRE)”, in which phase difference between objective and surrounding tissue is selected in order to enhance the contrast of objective tissue. Our objective is to clarify whether the high resolution PADRE reveals the anatomical structures within the SN and is useful for the diagnosis of PD.

First, we investigated the effects of varying the reconstitution parameters of PADRE imaging on the depiction of the anatomical structures of the midbrain using three healthy volunteers. The optimized PADRE could display the subregions of the SN as a striped appearance consisting of pars compacta and reticulate. Then, 12 patients with PD and 12 healthy controls (age- and gender-matched) underwent MRI including the optimized PADRE. For each subject, the contrast ratio (CR) between SN and ventral tegmental area was calculated, and two neuroradiologists analyzed the striped appearance of the SN according to the following scores: score 2 = clearly visualized; score 1 = partially visualized; and score 0 = obscured.

PD patients showed significantly higher mean CR than healthy controls (0.65 vs. 0.49, P <.001). The stripe of SN was obscured more frequently in PD than in healthy controls (0.44 vs 1.78, P <.001). When the obscuration of the SN stripe (score 0) was used as a diagnostic criterion of PD, the sensitivity and specificity were 100% and 90%, respectively.

The nigral stripe on PADRE was frequently obscured in patients with PD. This finding showed high accuracy for the diagnosis of PD.

For the diagnosis of PD, the obscuration of nigral stripe on phase difference enhanced imaging seems to have higher accuracy than any other MR findings previously reported.

Kakeda, S, Korogi, Y, Watanabe, K, Nishimura, J, Yoneda, T, Hiai, Y, Sato, T, Ohnari, N, Obscuration of Nigral Stripe in Parkinson's Disease: Evaluation on High-Resolution Phase Difference-enhanced Imaging.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006328.html