[Imaging of the brain: where is transcranial sonography superior to magnet resonance imaging?]

Transcranial sonography of brain parenchyma (TCS) using sophisticated clinical ultrasound systems today allows a higher image resolution of echogenic deep brain structures than magnet resonance imaging (MRI) under clinical conditions. Subtle changes of certain deep brain structures (substantia nigra, midbrain raphe, basal ganglia) such as abnormal trace metal accumulation and circumscribed degenerative processes can often be detected more sensitively with TCS than with conventional MRI. High mobility of modern ultrasound systems as well as low invasiveness, short investigation time and practically unlimited repeatability argue for the use of TCS for screening of populations at risk of certain neurodegenerative diseases, especially in the early diagnosis of Parkinson's disease. In addition, the high-resolution real-time imaging by TCS allows its application for the intra-operative monitoring of the insertion of deep brain stimulation electrodes. There TCS supports the correct positioning of electrodes while preventing haemorrhages by simultaneous depiction of brain arteries at the target region.