Cerebral blood flow, arterial pulsation, and vasomotion play important roles in the transport of waste metabolites out of the brain. Impaired vasomotion results in reduced driving force for the perivascular/glymphatic clearance of beta-amyloid. Noninvasive cerebrovascular characteristic features that potentially assess these transport mechanisms are mean blood flow (MBF) and pulsatility index (PI). In this study, 4D flow MRI was used to measure intra-cranial flow features, particularly MBF, PI, resistive index (RI) and cross-sectional area in patients with Alzheimer's disease (AD), mild cognitive impairment and in age matched and younger cognitively healthy controls. Three-hundred fourteen subjects participated in this study. Volumetric, time-resolved phase contrast (PC) MRI data were used to quantify hemodynamic parameters from 11 vessel segments. Anatomical variants of the Circle of Willis were also cataloged. The AD population reported a statistically significant decrease in MBF and cross-sectional area, and also an increase in PI and RI compared to age matched cognitively healthy control subjects. The 4D flow MRI technique used in this study provides quantitative measurements of intracranial vessel geometry and the velocity of flow. Cerebrovascular characteristics features of vascular health such as pulsatility index can be extracted from the 4D flow MRI data.

The popular press frequently reports that coat colour bias negatively impacts shelter adoption rates for black domestic dogs. This phenomenon, commonly called ‘black dog syndrome’ (BDS), reportedly increases the likelihood of euthanasia for black dogs and negatively affects the length of black dogs’ time to adoption. While organisations may focus on BDS and ways to promote black dogs, it is possible that the influences of other important factors, such as sex, age and breed, may be overlooked. To evaluate the veracity of BDS and examine the impact of various phenotypic traits on shelter outcomes, we analysed four years of intake and outcome data from two animal shelters in the Pacific Northwestern United States. Results indicated that the average length of availability for adoption (LOA) for black dogs was not significantly longer than that for other coloured dogs, nor was the rate of euthanasia of black dogs significantly higher than average. On the other hand, age and breed group were consistent predictors of shelter outcomes across the two shelters. Older dogs tended to have longer LOA and to be euthanised at rates higher than expected. Bully breeds had significantly longer LOA in both shelters and, compared to other breeds, were euthanised at higher than expected rates. The methods implemented in this study could be utilised by other shelters to inform intake and marketing strategies.

Objective The objective is to study the correlations between physical examination and stifle radiography findings and severity of arthroscopic cranial cruciate ligament (CrCL) fibre damage in dogs with cruciate rupture (CR).Design Design Prospective clinical study.Methods Twenty-nine client-owned dogs with CR underwent physical examination, stifle radiography and arthroscopy, and the findings were recorded. Initial examination was repeated after sedation and after general anaesthesia. The Spearman rank correlations of examination variables with diagnostic imaging were examined.Results Overall, cranial tibial translation assessed by the tibial compression test in extension showed correlation with arthroscopic CrCL fibre damage (P < 0.05). Correlations between severity of cranial drawer laxity and arthroscopic CrCL fibre damage were not significant. Under general anaesthesia, stifle laxity tests were positively correlated with lameness severity grade (S R ≥ 0.41, P < 0.05). Meniscal damage was correlated with pain on the internal rotation of the tibia (S R = 0.42, P < 0.05) and severity of radiographic osteophytosis (S R = 0.53, P = 0.01).Conclusion Detection and estimation of severity of cranial tibial translation enable the diagnosis of CR and also the inference of the severity of CrCL fibre rupture, particularly with the tibial compression test in extension. Severity of joint laxity is best assessed under general anaesthesia. Such knowledge should reduce the risk of misdiagnosis and may enhance early diagnosis and treatment of dogs with CR over time.

Background 2D digital subtraction angiography (DSA) is utilized qualitatively to assess blood velocity changes that occur during arterial interventions. Quantitative angiographic metrics, such as blood velocity, could be used to standardize endpoints during angiographic interventions. Purpose To assess the accuracy and precision of a quantitative 2D DSA (qDSA) technique and to determine its feasibility for in vivo measurements of blood velocity. Materials and methods A quantitative DSA technique was developed to calculate intra-procedural blood velocity. In vitro validation was performed by comparing velocities from the qDSA method and an ultrasonic flow probe in a bifurcation phantom. Parameters of interest included baseline flow rate, contrast injection rate, projection angle, and magnification. In vivo qDSA analysis was completed in five different branches of the abdominal aorta in two 50 kg swine and compared to 4D Flow MRI. Linear regression, Bland-Altman, Pearson’s correlation coefficient and chi squared tests were used to assess the accuracy and precision of the technique. Results In vitro validation showed strong correlation between qDSA and flow probe velocities over a range of contrast injection and baseline flow rates (slope = 1.012, 95% CI [0.989,1.035], Pearson’s r = 0.996, p < .0001). The application of projection angle and magnification corrections decreased variance to less than 5% the average baseline velocity (p = 0.999 and p = 0.956, respectively). In vivo validation showed strong correlation with a small bias between qDSA and 4D Flow MRI velocities for all five abdominopelvic arterial vessels of interest (slope = 1.01, Pearson’s r = 0.880, p = <.01, Bias = 0.117 cm/s). Conclusion The proposed method allows for accurate and precise calculation of blood velocities, in near real-time, from time resolved 2D DSAs.

The availability of 4D-DSA provides the opportunity to use the shifted least-squares method to estimate velocity in vessels within a 3D volume.