Estimación del tamaño normal de órganos o estructuras anatómicas mediante la realización de mediciones utilizando diferentes técnicas de imagen en perros y gatos

Abstract

In order to establish ultrasonographic reference values of certain organs in dogs and cats, we evaluated the relationship of the size of the following organs: adrenal glands, intestine and kidneys, with measurements of reference anatomical structures or with measurements obtained by other techniques (e.g. Histology), with the following objectives: 1.To estimate the thickness of the adrenal gland by ultrasonography in dogs without adrenal pathology, and to obtain an adrenal gland/Aorta ratio, using the diameter of the Ao as the reference anatomical structure. To establish the effect of body weight, sex and age of the animals on this ratio. 2. To perform ultrasonographic measurements of the wall and layers of the small intestine in cat cadavers without gastrointestinal pathology, to determine the relationship between the longitudinal and transverse planes, and to determine the agreement between these measurements and the histological measurements. 3. To estimate the length of the kidneys by ultrasonography and radiography, in cats without renal pathology, and to establish a kidney/vertebra ratio, using the length of the lumbar vertebrae (L5 and L6), as an anatomical reference structure. To determine the effect of age, weight, sex and reproductive status of the animals on the renal and vertebral lengths, and ratios. Material and methods: 1. The study included 234 dogs without adrenal pathology. The animals were distributed in 3 weight categories (<10 kg, 10-20 kg and >20 kg), and 4 age categories (<1 year, 1-5 years, 5-10 years and >10 years). Ultrasonographic images were obtained in sagittal plane, making measurements of the thickness of the caudal pole of both adrenal glands and the diameter of the aortic lumen, obtaining the different Adrenal/Ao ratios. 2. Seventeen adult cat cadavers that were euthanized for reasons other than gastrointestinal disease were included in the study. Ultrasound images of the duodenum, jejunum, ileum and distal ileum were obtained in longitudinal and transverse planes. Samples of the different intestinal portions were taken and histological preparations were performed. Measurements of the intestinal layers were taken and the total wall thickness was calculated from the ultrasonographic images and histological preparations. 3. Sixty cats were included in the study. The cats were divided into 3 age groups (<7 months, 7 months-7 years, and >7 years), 2 weight groups (≤3.5kg and >3.5 kg), and 2 sex and reproductive status groups (male and female, and intact and neutered, respectively). Measurements of renal length and the vertebral bodies of L5 and L6 were performed on ultrasonographic and radiological images. Two ultrasonographic ratios Kidney/L5 and Kidney/L6 were obtained. Conclusions: 1. The adrenal gland/aorta ratio was determined to estimate a reference ultrasonographic value of the adrenal glands in dogs without adrenal disease. This ratio was influenced only by body weight, being the values obtained 0.8 ± 0.17 (0.41-1.49) in dogs <10 kg, 0.68 ± 0.15 (0.4-1.06) in dogs 10-20 kg, and 0.61 ± 0.12 (0.31-0.83) in dogs > 20kg. 2. Ultrasonographic and histologic measurements of wall thickness and its layers in the different portions of the small intestine were obtained in cat cadavers without intestinal disease. a. Ultrasonographic measurements in the longitudinal and transverse planes showed differences only in the distal ileum at the level of the folds. For this reason, only the transverse plane was considered at this level. b. The ultrasound and histological measurements of the total thickness of the intestinal wall, and of the layers in the different intestinal segments, showed good agreement, with the exception of the submucosal and muscularis layers of the duodenum. The ultrasound thickness of the submucosal layer was thicker and the muscularis layer thinner in comparison with the histological thickness. 3. The ultrasonographic kidney length/vertebral length (L6) ratio was established in cats without renal disease to obtain a reference value of the kidney. The kidney/L6 ratio obtained 1.81 ± 0.20 (1.76 -1.86), was not influenced by any of the variables studied of age, weight, sex or gonadal status of the animals.