Analysis of grey scale distribution does not disclose a typical pattern in substantia nigra hyperechogenicity

Purpose: Substantia nigra hyperechogenicity in transcranial ultrasound studies (SN+) is a regular finding in patients with Parkinson's disease (PD) and has been suggested as a biomarker supporting clinical diagnosis. Based on animal and post-mortem studies, the increase of echogenicity at the anatomical site of the midbrain substantia nigra (SN) is believed to be caused by iron deposition and activated microglia, both pathophysiological phenomena in the course of PD. Anyhow, about 10% of healthy adults do exhibit SN+, too. Longitudinal studies could demonstrate an increased risk for PD leading to the question wh…