The assessment of vasomotor reactivity by transcranial Doppler ultrasound correlates with cerebral blood flow changes even when different vasodilatory stimuli are used. In cooperative patients the breath-holding maneuver as vasodilatory stimulus seems clinically useful for a first estimation of cerebral vasomotor reactivity.

No abstract

Stereotactic burr-hole procedures like biopsies of brain tumours based on CT scan or MRI and angiographic data have so far usually been carried out without real-time ultrasound image control. Intra-operative real-time ultrasound imaging was carried out during twelve target-point stereotactic procedures via a single standard burr-hole using a new slender ultrasound transducer with a diameter of 8 mm. The technical parameters of the transducer are: frequency range of 5 < - > 3.5 MHZ, phased array sector scan, 90 degree sector. The transducer has a bayonet-like configuration and can be sterilized. Sufficient quality of the images was achieved in these twelve cases with different pathological entities such as malformation cysts (3 cases), gliomas (7 cases), one metastasis and one intracerebellar haemorrhage. Moreover, co-ordinate values may be calculated from the ultrasound images generated peroperatively, allowing the surgeon to choose additional targets. Colour flow mapping provides the visualization of vascular structures. For the beginner stereotaxy may be easier to learn using ultrasound real-time imaging.

The behavior of cerebral tumors and their appearance on CT and MR images after interstitial irradiation seem to be variable. Decrease in tumor size may take place at different intervals after therapy. Brachytherapy of tumors with a diameter of > 4 cm may produce space-occupying radionecrosis.

No abstract