Methodological standards for Transcranial Sonography of brain parenchyma

Background This paper is the first in a series of narrative reviews highlighting the advancements in diverse applications of ultrasonography in Neurology. Neurological sonography is a cost-effective and safe neuroimaging method with expanding applications. Transcranial sonography (TCS) investigates the brain parenchyma with B-mode sonography insonating through the temporal bone windows with a 1-5 MHz transducer. It may assist in the differential diagnosis of movement disorders and, especially, of Parkinson's disease. More recently, a good correlation to MRI (Magnetic Resonance Imaging) in Alzheimer's dementia diagnosis was found. Objectives In the present paper we review the standardized method of transcranial sonography for B-mode (bidimensional) imaging of the brain parenchyma in movement disorders and other neurodegenerative conditions. Methods The authors used their experience with the method and reviewed the updated literature on the technique of TCS in the evaluation of brain parenchyma structures that are helpful in the diagnosis of neurological intracranial conditions. Results The structures that can be visualized and measured at four axial planes - mesencephalic, thalamic, ventricular bodies (cella media) and posterior fossa - and at a coronal plane - medial temporal lobe structures - are described. Conclusions Although ultrasonography is named an "operator-dependent" technique, this can be overcome by increasing standardization of the exam, sophistication of equipment software and by expanding expertise among specialists.