Purpose: Using transcranial color coded duplex sonography (TCCS) it is possible to visualize intracranial arteriovenous malformations (AVMs). The purpose of this study is to describe their typical ultrasonographic features and to define sensitivity for diagnosis with regard to the localization of an AVM.
Materials and methods: Over a period of six years we prospectively examined 54 intracranial AVMs confirmed by angiography. Using TCCS the vessels of the circle of Willis were identified by location, course and direction of flow on color flow images. The examination was performed during the first three years of the study using the Acuson 128 XP 10 system, equipped with a sector transducer with a 2.0/2.5 - MHz imaging frequency for the transcranial examination, and with a 7.0 MHz linear transducer fot the extracranial examination. During the second three years of the study, transcranial examination was performed with an Acuson Seqouia 512 ultrasound system equipped with a 2 - 4 MHz phased array transducer.
Results: In accordance with digital subtraction angiography, the intracranial AVMs could be visualized in 42 cases (77.8 %). The major feeding vessels of the AVMs could be easily identified due to typical hemodynamic parameters showing increased systolic and diastolic flow velocities and decreased pulsatility index. We failed to visualize AVMs localized near the cortex, i. e. in the parietal, frontal, occipital and cerebellar regions of the brain. In contrast, 88.9 % of AVMs localized in the basal regions were very easy to image. Additionally, TCCS was useful for postoperative or postinterventional follow-up, although only a limited number of patients could be examined by TCCS in the post-treatment period.
Conclusion: TCCS is a noninvasive method for the diagnosis and possibly valuable in the long-term follow-up of intracranial AVMs. However, further research is needed to establish TCCS as an imaging modality in the follow-up after treatment of AVMs. The method can be regarded as a useful supplement to the palette of established, noninvasive diagnostic techniques such as MRI and MRA. However, since TCCS cannot rule out an AVM, angiography is still the method of choice for the definitive diagnosis.