Paediatric Cerebral Arteriovenous Malformations: Value of Colour Doppler Ultrasound in the Diagnosis and Management of Endovascular Treatment

Abstract

Colour Doppler ultrasound is a new diagnostic method in neuroradiology allowing the non invasive imaging of parenchymal and vascular structures in adults as in children through the intact skull.In particular, this study describes the use of colour Doppler US in children with intracranial arteriovenous malformations to determine its value in the evaluation of haemodynamic changes in cerebral vessels. To test the hypothesis that colour Doppler US analysis of spectral waveforms can be considered an indirect measurement of volume flow in major arteries and veins, we performed 13 colour Doppler US examinations on 4 children with vein of Galen malformations, 2 with parenchymal arteriovenous malformations and 7 children with facial angiomas, before the endovascular treatment, immediately thereafter and after a short time.Peak systolic and end-diastolic flow velocities, resistive index and pulsatility index, quantitative expression of cerebral blood flow, was attempted, while qualitative parameters such as blood flow direction, spectral waveform morphology and spectral broadening were not considered useful in the study.Colour Doppler US performed after endovascular treatment showed:a decrease of main feeder flow velocity and an increased pulsatility index and/or resistive index (as indirect measurement of increased peripheral stream resistance); the presence of echogenic foci within blood vessels, in the nidus or in the vein of Galen, representing embolisation materials or thrombi, such as residual color flow in the same embolised vascular territories; decreased blood flow velocity and spectral broadening in draining veins, indicating an incomplete occlusion of fistulas.In one case of vein of Galen malformation, we performed colour Doppler US three days after the embolisation, showing the occlusion by thrombi of the vein of Galen and of the draining veins.Colour Doppler US can be considered a valuable method for non-invasive haemodynamic assessment of blood flow in cerebral arteriovenous malformations. With this procedure, allowing serial examinations with unlimited repeatability and by using portable equipment at the patient' bedside, it is possible to monitor haemodynamic changes after embolisation.This limits the use of more invasive procedures such as CT, MR and angiography and the relatively large amounts of contrast material and radiation dose.