Background: Bone subtraction computed tomography angiography (BSCTA) is a useful alternative technique for improving visualization of vessels surrounded by skull bone.However, no studies have compared computed tomography angiography (CTA) and BSCTA for improving the visibility of canine cerebral blood vessels. Objectives: To evaluate the potential benefit of BSCTA for better delineation of brain arteries of the circle of Willis (CoW) in dogs by comparing BSCTA with non-subtraction computed tomography angiography (NSCTA). Methods: Brain CTA was performed for nine healthy beagle dogs using a bolus tracking method with saline flushing. A total dose of 600 mgI/kg of contrast agent with an iodine content of 370 mgI/mL was injected at a rate of 4 ml/s. Bone removal was achieved automatically by subtracting non-enhanced computed tomography (CT) data from contrast CT data. Five main intracranial arteries of the CoW were analyzed and graded on a scale of five for qualitative evaluation. Results: Scores of basilar artery, middle cerebral artery, and rostral cerebral artery in the BSCTA group were significantly higher than those in the NSCTA group (p = 0.001, p = 0.020, and p < 0.0001, respectively). Scores of rostral cerebellar artery (RcA) and caudal cerebral artery (CCA) did not differ significantly between the two groups. However, scores of RcA and CCA in the BSCTA group were higher than those in the NSCTA group. Conclusions BSCTA improved visualization of intracranial arteries of the CoW with close contact to bone. Thus, it should be recommended as a routine scan method in dogs suspected of having brain vessel disease.

A 5-year-old castrated male domestic shorthair cat was referred for further investigation of pulmonary nodules incidentally detected on thoracic radiographs. Thoracic radiographs identified ill-defined soft tissue opacity nodules with small faint mineral opacity. Thoracic computed tomography (CT) revealed that bronchial dilation and bronchial wall thickening in bilateral cranial and accessory lung lobes. Round to ellipsoid mineralized concretions were found embedded in the intrabronchial soft tissue attenuation material. Based on radiography, CT, and cytology, the patient was tentatively diagnosed as having broncholithiasis with chronic bronchitis. This report described the CT diagnosis of broncholithiasis, which has been rarely reported in a cat.