The vertebral heart scale on CT is correlated to radiographs in dogs.

The vertebral heart scale (VHS) has long been used as an objective standard for evaluation of cardiac silhouette size on thoracic radiographs and plays a key role in the diagnosis as well as the assessment of the severity of canine heart disease. Based on our review of the literature, there has been no published study describing an objective method for measuring overall heart size using computed tomography (CT) in canine patients. The goals of this exploratory prospective method comparison study were to describe a method for objectively evaluating heart size on canine thoracic CT images, determine whether there was a correlation between the VHS when applied to a right lateral thoracic radiograph and a sagittal image of a thoracic CT scan, and determine the effect of cardiac phase on a VHS measured on CT. A method for measuring VHS on canine CT studies was defined. Data were collected on canine patients admitted to The Ohio State Veterinary Medical Center. Each patient received an ECG-gated thoracic CT immediately followed by a right lateral thoracic radiograph. The VHS was measured on non-gated, systolic, and diastolic sagittal CT reformatted images. Our results indicated that cardiac gating may not be necessary when assessing canine heart size on CT. When comparing the VHS on gated and non-gated CT to the VHS on radiographs, there was a moderate to high degree of correlation; however, there was a high degree of variability between CT and radiography.

Comparison of high-field MRI and multidetector CT for grading Chiari-like malformation and syringomyelia in Cavalier King Charles Spaniels.

Chiari-like malformation (CM) and syringomyelia (SM) are common illnesses that can cause debilitating neuropathic pain in Cavalier King Charles spaniels (CKCS). The current imaging modality to screen CKCS for CM/SM is MRI of the brain and cervical spine. Magnetic resonance imaging provides good soft tissue detail and contrast of the cerebellum and cervical spinal cord. Computed tomography (CT) is another cross-sectional imaging technique that facilitates brain and neck evaluation; however, soft tissue resolution does not match that of MRI. Computed tomography benefits include identification of concurrent craniocervical junction anomalies (atlantooccipital overlap) and shorter imaging/anesthesia times with the ability to use only sedation. The aim of this retrospective, method comparison study is to assess the utility of multidetector CT for screening CM and SM in CKCS as compared to high-field MRI. Three groups of observers with different levels of experience graded CM and SM based on the British Veterinary Association/Kennel Club CM/SM classification criteria. Thirty CKCS underwent multidetector CT and 3 Tesla MRI studies. Computed tomography and MRI studies were reviewed at different timepoints to minimize bias. Computed tomography has lower Cohen's Kappa agreement for each observer group compared to MRI. The intraclass correlation coefficient averaging CM and SM for all groups was excellent using MRI, while CT was poor for SM and moderate for cerebellar herniation. Greater observer experience resulted in a higher agreement for CT and MRI. Magnetic resonance imaging should remain the standard for screening of CM and SM as CT can result in misclassification and greater disagreement.