Hakyoung Yoon

Diffusion tensor imaging of white and grey matter within the spinal cord of normal Beagle dogs: Sub-regional differences of the various diffusion parameters

Diffusion tensor imaging (DTI) is an advanced diffusion weighted imaging technique that can identify early stage lesions and Wallerian degeneration within the spinal cord; these changes are difficult to recognise on conventional magnetic resonance imaging (MRI). The only DTI parameters previously investigated in dogs are fractional anisotropy and mean diffusivity (MD). The aim of this study was to evaluate multiple DTI parameters in sub-regional areas of the spinal cord in normal Beagles. All imaging data were obtained from the lumbar spinal cord (L1-L3) of ten normal dogs using a 3 Tesla MRI scanner. Transverse multi-shot echo planar imaging sequences (b values = 0 and 800 s/mm(2); 12 directions) were used for DTI. Regions of interest were selected from sub-regions of the white and grey matter, and from the whole spinal cord, in the transverse plane in all DTI maps. The DTI parameters in spinal cord sub-regions in the transverse plane were significantly different amongst the white matter, grey matter and whole spinal cord (P < 0.05 for all DTI parameters except MD), as well as between white matter sub-regions (P < 0.05 for most DTI parameters except radial diffusivity, MD and planar index). DTI-based sub-regional analysis of white and grey matter may be useful for regional evaluation of the dog spinal cord.

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHIC ANGIOGRAPHY CHARACTERISTICS OF MULTIPLE VASCULAR ANOMALIES IN A SENIOR DOG WITH LATE-ONSET REGURGITATION

A 10-year-old dog weighing 3.4 kg presented with intermittent regurgitation. Esophagography revealed that the thoracic esophagus was compressed dorsally at the region of the fourth intercostal space and segmentally dilated from the second to third intercostal region. Three-dimensional computed tomographic (CT) angiography confirmed a suspected vascular ring anomaly and also revealed multiple other vascular anomalies. These included aberrant right subclavian artery, absence of bilateral external jugular veins, right-gastric caval shunt, and a completely duplicated caudal vena cava. Findings supported the use of thoracic CT angiography to rule out additional vascular malformations in dogs with suspected vascular ring anomaly.

Quantitative computed tomographic evaluation of bone mineral density in beagle dogs: comparison with dual-energy x-ray absorptiometry as a gold standard

This study aimed to demonstrate the higher accuracy and reproducibility of quantitative computed tomography (QCT) compared with dual-energy X-ray absorptiometry (DXA) as a gold standard for measuring canine bone mineral density (BMD). Seven middle-aged beagle dogs underwent lumbar vertebral and bilateral femoral DXA and QCT scans. BMD (mg/cm2) was measured at the vertebral body from L2 to L6, femoral neck, and proximal and distal femoral diaphyses. The BMD values were measured 3 times and compared. The BMD value on QCT was higher than that on DXA for femoral BMD but not for vertebral BMD. The correlation was strong for the lumbar vertebrae (r=0.66) and was strongest for L3 (r=0.85). No correlation was found for the femoral neck (P=0.35), and only moderate correlations were found for the proximal and distal femoral diaphyses (r=0.43 and r=0.40, respectively). The limits of agreement were narrower for vertebral BMD than for femoral BMD, and L3 had the narrowest limits of agreement. The intraclass correlation (ICC) was higher for DXA than for QCT at all lumbar and femoral sites measured, but the ICC of QCT was higher than 0.7. In conclusion, L3 can be used to monitor changes in BMD, and relative values and sequential monitoring of femoral BMD can also be useful because of the high reproducibility of QCT measurements. QCT would be a useful technique for evaluation of BMD in veterinary practice.

Urogenital anomalies and urinary incontinence in an English Cocker Spaniel dog with XX sex reversal

A 3‐year‐old dog weighing 8 kg was referred with a disorder of sexual development and persistent urinary incontinence before and after gonadohysterectomy performed at a local animal hospital. Histopathological examination disclosed hypoplasia of the testes, epididymis, pampiniform plexus, and uterus. On ultrasonography, an anomalous structure containing anechoic fluid was identified in the region dorsal to the urinary bladder. An anomalous communication between the proximal urethra and the remnant uterus and vagina was found on retrograde urethrography under fluoroscopy. Reflux of contrast medium into the anomalous structure, suspected to be the uterus and cranial vagina, from the urethra was detected. Computed tomography identified the anomalous structure between the rectum and urethra. The anomalous structure was removed via laparotomy and the urinary incontinence resolved. The diagnosis of XX sex reversal with a developmental anomaly of the genitourinary tract was made on the basis of laparotomy findings and cytogenetic and SRY gene analyses.

IMAGING DIAGNOSIS-A LUMINAL LAMINATED DEBRIS BALL IN THE URINARY BLADDER OF A DOG.

A 5-year-old dog presented with pollakiuria and urinary incontinence. Abdominal radiographs revealed an oval, multilayered structure with soft tissue opacity and gas lucency in the urinary bladder. Ultrasonography showed an oval luminal structure with hyper- and hypoechoic layers and internal reverberation artifacts. Following cystotomy, the hemisected plane showed a layered, pale whitish matrix with a gas layer around the core. Histopathological examination showed no evidence of cells, bacteria, or fungi. The core and laminae comprised fibrinous and mineral debris. A final diagnosis of a freely floating, gas-filled laminated debris ball was made.

Multimodality imaging characteristics of tension pyopneumothorax secondary to pulmonary carcinoma in a cat

A 3-year-old Himalayan cat was presented with respiratory distress. Radiography showed multiple gas opacity foci, with the locations dependent on patient positioning, and severe pleural effusion with a contralateral mediastinal shift. A large volume of fluid and air was aspirated, and the fluid components were consistent with a nonseptic exudate. A pulmonary mass, pleural nodules, and an air-fluid interface with air bubbles trapped in fibrous septations were identified using thoracic ultrasonography and CT. The cat died 2 days after imaging studies. Necropsy revealed tension pyopneumothorax caused by pulmonary carcinoma and multiple pleural metastases.

Computed tomography angiography reveals stenosis and aneurysmal dilation of an aberrant right subclavian artery causing systemic blood pressure misreading in an old Pekinese dog

A 14-year-old dog weighing 4 kg presented with hypotension only in the right forelimb. Thoracic radiography revealed a round soft tissue opacity near the aortic arch and below the second thoracic vertebra on a lateral view. Three-dimensional computed tomography angiography clearly revealed stenosis and aneurysmal dilation of an aberrant right subclavian artery. Stenosis and aneurysm of an aberrant subclavian artery should be included as a differential diagnosis in dogs showing a round soft tissue opacity near the aortic arch and below the thoracic vertebra on the lateral thoracic radiograph.