Microvessels may Confound the "Swallow Tail Sign" in Normal Aged Midbrains: A Postmortem 7 T SW-MRI Study.

Background And Purpose: Susceptibility weighted imaging (SWI) plays a role in the differential diagnosis of Parkinson's disease, but lacks widespread acceptance in clinical routine. In a descriptive pilot study, we assessed hypointense microstructures of the normal substantia nigra pars compacta at ultrahigh-field strength for interpretation of the "swallow tail sign."

Methods: Magnetic resonance imaging at 7 Tesla was performed in five postmortem samples obtained from subjects not affected by Parkinson's disease.

The influence of brain iron and myelin on magnetic susceptibility and effective transverse relaxation - A biochemical and histological validation study.

Quantitative susceptibility mapping (QSM) and effective transverse relaxation rate (R2*) mapping are both highly sensitive to variations in brain iron content. Clinical Magnetic Resonance Imaging (MRI) studies report changes of susceptibilities and relaxation rates in various neurological diseases which are often equated with changes in regional brain iron content. However, these mentioned metrics lack specificity for iron, since they are also influenced by the presence of myelin.

Noise reduction in FLAIR images using total generalized variation, Gaussian and Wiener filtering.

Purpose: Multiplication of FLAIR and T2-weighted MRI scans results in images (called FLAIR) with an improved contrast-to-noise ratio (CNR) for multiple sclerosis (MS) lesions but with a reduced signal-to-noise ratio (SNR). Denoising of these images may therefore further improve FLAIR image quality. The purpose of this work is to present a systematic investigation of FLAIR image denoising methods using Gaussian, Wiener and Total Generalized Variation (TGV) filtering approaches.