Color Flow Doppler Imaging and Doppler Spectral Analysis of the Brain of Neonatal Dogs

Abstract

Doppler ultrasonography was performed on the cerebral arteries of 19 neonatal dogs. Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed or examined under a stereomicroscope. Color flow Doppler imaging was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured in transverse images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.

Foetal echoencephalography and Doppler ultrasonography of the middle cerebral artery in canine foetuses

“…During the 6th, 7th and 8th gestational weeks, pulsed Doppler ultrasonography was performed to assess the PSV, end‐diastolic velocity (EDV), resistance indice (RI=[PSV−EDV]/PSV) and pulsatility index (PI=[PSV−EDV]/mean velocity) of the middle cerebral artery of the foetuses directly from Doppler waveforms using the ultrasound machine's electronic callipers (Hudson et al . ).…”

Small breed dogs with confirmed stroke: concurrent diseases and sonographic findings

“…The brain has efficient compensatory hemodynamic mechanisms that maintain normal intracranial pressure and RI (Guyton and Hall, 2000), but the waveform of the affected vessel may be compromised in the correspondent territory (Nagai et al, 1997). Although the deposition of atheromatous plaques does not happen naturally in the aging process of the dog, it is known that animals which have diseases that lead to changes in cholesterol metabolism may have vascular stenosis similar to that which occurs in humans (Pattersen et al, 1985;Joseph et al, 1987;Braund, 1994;Garosi, 2010). These promote vascular stenosis in several degrees (Burgin et al, 2000) and can be detected by Doppler spectral (Nagai et al, 1997;Fukushima et al, 2000;Saito et al, 2003;Carvalho et al, 2007;Carvalho et al, 2010a;Carvalho et al, 2010b).…”

“…The vessels of the arterial circle were considered normal when observed with minimum adjustment of Doppler color gain settings, without aliasing. Special attention was given to obtaining a correct insonation angle to maximize the Doppler signal, as described in technical reports in previous literature literature (Hudson et al, 1997;Fukushima et al, 1999;Seo et al, 2005;Carvalho et al, 2009;Duque et al, 2009). Once the vessels were identified, the pulsed wave Doppler was initiated, and a spectral tracing with three similar sequential waveforms was collected.…”

“…These diseases became clinically important because of the recognized impact in the cognitive, neurological and well-being areas of the dog. Previously considered uncommon, cerebrovascular disease is being recognized with greater frequency in veterinary medicine since imaging techniques such as ultrasonography, computed tomography and magnetic resonance have become more readily available (Joseph et al, 1987). Stroke is currently one of the leading causes of human death (Joseph et al, 1987;Garosi, 2010) but its occurrence in dogs is not well known.…”

“…Cerebrovascular diseases in dogs are defined as brain abnormalities caused by blood supply impairment (Joseph et al, 1987;Garosi, 2010). These diseases became clinically important because of the recognized impact in the cognitive, neurological and well-being areas of the dog.…”