. The aim of this study was to assess age-related changes and anatomic variation in trabecular bone mineral density (tBMD) using quantitative computed tomography (QCT) in normal cats. Seventeen normal cats were included in this study and divided into the following 3 age groups:<6 months (n=4), 2-5 years (n=10) and >6 years (n=3). A computed tomographic scan of each vertebra from the 12th thoracic to the 7th lumbar spine and the pelvis was performed with a bone-density phantom (50, 100 and 150 mg/cm 3 , calcium hydroxyapatite, CIRS phantom ® ). On the central transverse section, the elliptical region of interest (ROI) was drawn to measure the mean Hounsfield unit (HU) value. Those values were converted to equivalent tBMD (mg/cm 3 ) by use of the bone-density phantom and linear regression analysis (r 2 >0.95). The mean tBMD value of the thoracic vertebrae (369.4 ± 31.8 mg/cm 3 ) was significantly higher than that of the lumbar vertebrae (285 ± 58.1 mg/cm 3 ). The maximum tBMD occurred at the T12, T13 and L1 levels in all age groups. There was a statistically significant difference in the mean tBMD value among the 3 age groups at the T12 (P<0.001), T13 (P<0.001) and L4 levels (P=0.013), respectively. The present study suggests that age-related changes and anatomic variation in tBMD values should be considered when assessing tBMD using QCT in cats with bone disorders. KEY WORDS: bone mineral density, feline, quantitative computed tomography, trabecular bone. doi: 10.1292/jvms.11-0579; J. Vet. Med. Sci. 74(11): 1461-1467, 2012 Bone mineral density (BMD) decreases in accordance with normal aging and metabolic or systemic disease. The turnover rates for cancellous bone are 4 to 8 times greater than for cortical bone, so cancellous bone is more sensitive to disease-induced changes [25]. Therefore, in humans with osteoporosis, BMD has been primarily investigated in cancellous bone.On the basis of this relationship, several techniques have been developed to noninvasively measure bone mineralization at various skeletal sites. These include radioabsorptiometry (RA), single photon absorptiometry (SPA), dual photon absorptiometry (DPA), quantitative ultrasound (QUS), dual-energy x-ray absorptiometry (DEXA), quantitative computed tomography (QCT) and peripheral QCT (pQCT). Among these, DEXA, QCT and pQCT have become the established methods for evaluating skeletal status, assessing osteoporosis, determining fracture risk and monitoring metabolic diseases and therapies in humans [8,[10][11][12][13].Feline diseases affecting BMD include mucopolysaccharidosis, osteopetrosis, osteogenesis imperfect and osteopenia related to primary hyperparathyroidism and secondary to renal or nutritional hyperparathyroidism. Reports in cats have been limited to the studies for BMD evaluation using DEXA [17] and a few peer-reviewed studies that measured BMD in clinically normal cats and abnormal cats using DEXA [3,23]. DEXA has been accepted as the gold standard method of BMD measurement, and it requires less X-ray exposure for the patient...

ABSTRACT. The purposes of this study were to determine the optimal dose and delay time for lymphography by injection of Iohexol into popliteal lymph nodes and to assess images of computed tomography by the established protocol. Three different doses (30, 60 and 90 mgI/kg) of water-soluble iodinated contrast medium were injected into 15 popliteal lymph nodes of 10 adult beagles, and fluoroscopy was performed. Filling and duration of contrast media and the number of visible ducts from popliteal lymph nodes to the thoracic duct and its branches were recorded. CT lymphography was performed, and the number of visible thoracic ducts was compared with that found by radiographic lymphography. Radiographs obtained between 130 and 800 seconds after injection of contrast medium provided a detailed view of the thoracic duct. The dose of 60 mgI/kg was determined to enable quality diagnostic imaging without extranodal leakage in radiographic lymphography. There was no significant difference in the number of thoracic ducts between the two modalities at each anatomic location. However, CT lymphography provided images of the thoracic duct with better spatial resolution and without superimposition of surrounding tissue. The present study provides an adequate delay time and injection for identification of the canine thoracic duct, and therefore, this technique could be applied to diagnosis of disease associated with chest lymphatic drainage.KEY WORDS: CT, dog, Percutaneous ultrasound guided popliteal lymphograhy, thoracic duct.

Computed tomographic arthrography (CTA) of four cadaveric canine stifles was performed before and after partial cranial cruciate ligament rupture in order to verify the usefulness of CTA examination for the diagnosis of partial cranial cruciate ligament rupture. To obtain the sequential true transverse image of a cranial cruciate ligament, the computed tomography gantry was angled such that the scanning plane was parallel to the fibula. True transverse images of cranial cruciate ligaments were identified on every sequential image, beginning just proximal to the origin of the cranial cruciate ligament distal to the tibial attachment, after the administration of iodinated contrast medium. A significant decrease in the area of the cranial cruciate ligament was identified on CTA imaging after partial surgical rupture of the cranial cruciate ligament. This finding implies that CTA can be used for assessing partial cranial cruciate ligament ruptures in dogs.