When the brain structure of interest is clearly displayed, the image should be fixed and zoomed in two- to three-fold for further measurements [11]. The examination is performed at axial scanning planes through the midbrain and the thalami [11] and [12]. The mesencephalic brainstem can be depicted as a butterfly shaped structure of low echogenicity surrounded by the highly echogenic basal cisterns. The echogenicity of the ipsilateral SN, red nucleus (RN) and the BR could be evaluated (Fig. 1). The BR is usually seen as a highly echogenic continuous line with an echogenicity that selleck kinase inhibitor is identical to that of the RN [13]. Echogenicity of BR is rated semiquantitatively, using either a 3-point (grade

1: raphe invisible; grade 2: slightly echogenic or interrupted BR; grade 3: high echogenicity

identical to that of RN or basal cisterns) or, preferably, a 2-point (grade 0: invisible, hypoechogenic or interrupted BR; grade 1: highly echogenic BR as RG7422 molecular weight a continuous line) grading system [13]. It is important to scan the subject investigated from both sides, as the bone window may vary allowing sufficient visualization of the BR only if both sides are considered. Therefore, if the BR can be depicted as continuous line from one side, it is rated as a normal (grade 1) – that is, hyperechogenic, non-interrupted continuous line. Changes in raphe echogenicity reflect changes in tissue impedance and point towards an alteration of the brainstem microarchitecture which could be due to a shift in tissue cell density, a change in interstitial matrix composition, or an alteration of fiber tract integrity [5] and [14]. Various anatomical, physiological, and biochemical findings underline the importance of the basal

limbic system in the pathogenesis of affective disorders, and compelling evidence suggests that the nuclei, fiber tracts, and neurotransmitter systems associated with the basal limbic system are involved in the pathogenesis of primary depression and depression associated with some neurodegenerative diseases such as PD [15] and [16]. The change of acoustic impedance, which is recorded by TCS as reduced clonidine BR echogenicity, might be the result of microstructual changes, gliosis and disruption of fiber tract integrity [14]. Numerous evidence from neuroimaging, biochemical and animal studies implicates basal limbic system and raphe nuclei involvement in the pathogenesis of the mood disorders, particularly depression. Typical ultrasound marker that can be of value in the diagnosis and differential diagnosis of depression is the low echogenicity or interrupted BR. Raphe hypoechogenicity is a common finding in 50–70% of patients with unipolar depression [2] and [17] and is associated with responsivity to serotonin-reuptake inhibitors (SSRI) [18]. In a pioneer study, echogenicity of the BR was examined by TCS in 20 patients with unipolar depression and 20 healthy adult controls.