Computed tomography exam of the thorax of bitches with malignant mammary gland tumors: I - Technical exam determination

Abstract

Given the importance of malignant mammary gland tumors in veterinary medicine clinics, new perspectives of diagnostic imaging in order to evaluate pacients that have this neoplasia, and the lack of information about it in literature, this research intended to analyse some technical aspects of the contrast computed tomography scanning. The scanning time, the choice of the axial slices thickness, quality of the mediastinal vases contrast and the window width and level were studied in order to have images that make possible the evaluation of lungs, mediastinum, and bones. This research was performed at the Diagnostic Imaging Service of the Veterinary School Hospital of the Faculdade de Medicina Veterinária e Zootecnia at the University of São Paulo in twenty, different breed and age, bitches with malignant mammary gland tumors that were examined at the Obstetric and Ginecology and Small Animal Surgery Services of the same hospital. The average time for the complete contrast computed tomography scanning of the thorax, with nearly 30 slices, was thirty minutes; the ventral recumbency with the cranial traction of thoracic limbs, and the administration of intravenously iodine contrast medium (2ml/kg) that was given; two thirds of the dose in bolus and the complement under continuing infusion presented to be appropriate for the thoracic contrast computed tomography scanning. The 10 milimeters thickness for animals weighting over 30 kilograms and 5 milimeters for animals weighting under 30 kilograms presented to be appropriate in order to reach an average of thirty slices; the window and level selections to obtain pulmonary, mediastinal and bone images presented appropriate to be evaluated starting from window width 1500 Hounsfield unit (HU) with level varyng from -550 e -650 for lungs, window width between 250 to 300 HU with level varyng from 0 e 50 for mediastinum and window width of 1500 with the level between 50 and 350 HU.