MR Imaging of the Substantia Nigra at 7 T Enables Diagnosis of Parkinson Disease

A potential role of MRI in PD is growing. This interesting paper demonstrates structural changes and signal changes that differentiated PD patients from healthy controls. Obviously it would be useful to replicate this in a larger number of subjects and study the appearances of patients with atypical parkinsonian disorders too. But as well as playing a possible role in diagnosis, it may have a role in early detection, perhaps even in the pre-diagnostic phase. Furthermore it may help us understand some the abnormalities seen with other imaging modalities such as transcranial sonography - Alastair Noyce

Radiology. 2014 Feb 26:131448. [Epub ahead of print]

Cosottini M, Frosini D, Pesaresi I, Costagli M, Biagi L, Ceravolo R, Bonuccelli U, Tosetti M.

Author information

From the IMAGO7 Foundation, Pisa, Italy (M. Cosottini, M. Costagli); Department of Translational Research and New Surgical and Medical Technologies (M. Cosottini) and Neurology Unit, Department of Clinical and Experimental Medicine (D.F., R.C., U.B.), University of Pisa, Pisa, Italy; Neuroradiology Unit, Department of Diagnostic and Interventional Radiology, Azienda Ospedaliero-Universitaria Pisana (AOUP), Pisa, Italy (I.P.); and Stella Maris Scientific Institute, Pisa, Italy (L.B., M.T.).

Abstract

Purpose To evaluate the anatomy of the substantia nigra (SN) in healthy subjects by performing 7-T magnetic resonance (MR) imaging of the SN, and to prospectively define the accuracy of 7-T MR imaging in distinguishing Parkinson disease (PD) patients from healthy subjects on an individual basis. Materials and Methods The 7-T MR imaging protocol was approved by the Italian Ministry of Health and by the local competent ethics committee. SN anatomy was described ex vivo on a gross brain specimen by using highly resolved proton-density (spin-echo proton density) and gradient-recalled-echo (GRE) images, and in vivo in eight healthy subjects (mean age, 40.1 years) by using GRE three-dimensional multiecho susceptibility-weighted images. After training on appearance of SN in eight healthy subjects, the SN anatomy was evaluated twice by two blinded observers in 13 healthy subjects (mean age, 54.7 years) and in 17 PD patients (mean age, 56.9 years). Deviations from normal SN appearance were described and indicated as abnormal, and both diagnostic accuracy and intra- and interobserver agreement for diagnosis of PD with 7-T MR imaging were calculated. Results Three-dimensional multiecho susceptibility-weighted 7-T MR imaging reveals a three-layered organization of the SN allowing readers to distinguish pars compacta ventralis and dorsalis from pars reticulata. The abnormal architecture of the SN allowed a discrimination between PD patients and healthy subjects with sensitivity and specificity of 100% and 96.2% (range, 92.3%-100%), respectively. Intraobserver agreement (κ = 1) and interobserver agreement (κ = 0.932) were excellent. Conclusion MR imaging at 7-T allows a precise characterization of the SN and visualization of its inner organization. Three-dimensional multiecho susceptibility-weighted images can be used to accurately differentiate healthy subjects from PD patients, which provides a novel diagnostic opportunity.