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- Author or Editor: Jimmy H. Saunders x
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Abstract
Objective—To compare computed tomography (CT) images of equine tarsi with cross-sectional anatomic slices and evaluate the potential of CT for imaging pathological tarsal changes in horses.
Sample—6 anatomically normal equine cadaveric hind limbs and 4 tarsi with pathological changes.
Procedures—Precontrast CT was performed on 3 equine tarsi; sagittal and dorsal reconstructions were made. In all limbs, postcontrast CT was performed after intra-articular contrast medium injection of the tarsocrural, centrodistal, and tarsometatarsal joints. Images were matched with corresponding anatomic slices. Four tarsi with pathological changes underwent CT examination.
Results—The tibia, talus, calcaneus, and central, fused first and second, third, and fourth tarsal bones were clearly visualized as well as the long digital extensor, superficial digital flexor, lateral digital flexor (with tarsal flexor retinaculum), gastrocnemius, peroneus tertius, and tibialis cranialis tendons and the long plantar ligament. The lateral digital extensor, medial digital flexor, split peroneus tertius, and tibialis cranialis tendons and collateral ligaments could be located but not always clearly identified. Some small tarsal ligaments were identifiable, including plantar, medial, interosseus, and lateral talocalcaneal ligaments; interosseus talocentral, centrodistal, and tarsometatarsal ligaments; proximal and distal plantar ligaments; and talometatarsal ligament. Parts of the articular cartilage could be assessed on postcontrast images. Lesions were detected in the 4 tarsi with pathological changes.
Conclusions and Clinical Relevance—CT of the tarsus is recommended when radiography and ultrasonography are inconclusive and during preoperative planning for treatment of complex fractures. Images from this study can serve as a CT reference, and CT of pathological changes was useful.
Abstract
Objective—To provide a detailed computed tomography (CT) reference of the anatomically normal equine stifle joint.
Sample—16 hind limbs from 8 equine cadavers; no horses had evidence of orthopedic disease of the stifle joints.
Procedures—CT of the stifle joint was performed on 8 hind limbs. In all limbs, CT was also performed after intra-articular injection of 60 mL of contrast material (150 mg of iodine/mL) in the lateral and medial compartments of the femorotibial joint and 80 mL of contrast material in the femoropatellar joint (CT arthrography). Reformatted CT images in the transverse, parasagittal, and dorsal plane were matched with corresponding anatomic slices of the 8 remaining limbs.
Results—The femur, tibia, and patella were clearly visible. The patellar ligaments, common origin of the tendinous portions of the long digital extensor muscle and peroneus tertius muscle, collateral ligaments, tendinous portion of the popliteus muscle, and cranial and caudal cruciate ligaments could also be consistently evaluated. The cruciate ligaments and the meniscotibial ligaments could be completely assessed in the arthrogram sequences. Margins of the meniscofemoral ligament and the lateral and medial femoropatellar ligaments were difficult to visualize on the precontrast and postcontrast images.
Conclusions and Clinical Relevance—CT and CT arthrography were used to accurately identify and characterize osseous and soft tissue structures of the equine stifle joint. This technique may be of value when results from other diagnostic imaging techniques are inconclusive. The images provided will serve as a CT reference for the equine stifle joint.
Abstract
Objective—To assess vascular changes induced by hyperadrenocorticism of hyperplastic adrenal glands in dogs via contrast-enhanced ultrasonography.
Animals—12 dogs with pituitary-dependent hyperadrenocorticism (PDH) and 7 healthy control dogs ≥ 7 years old.
Procedures—Dogs were assigned to the PDH and control groups and to small-breed (n = 6), medium-breed (4), and large-breed (9) subgroups. Contrast-enhanced ultrasonography of both adrenal glands in each dog was performed with IV injections of contrast agent. Time-intensity curves for the adrenal cortex, adrenal medulla, and ipsilateral renal artery of both adrenal glands were generated. Perfusion variables (time to peak [TTP], upslope of wash-in phase, and downslope of washout phase) were calculated.
Results—Contrast-enhanced ultrasonography revealed no qualitative difference between PDH and control groups. Quantitatively, TTPs were longer in the adrenal cortex and adrenal medulla of the PDH group, compared with values for the control group, particularly in the adrenal cortex and adrenal medulla of the small-breed subgroup. Washout downslopes were lower for the renal artery, adrenal cortex, and adrenal medulla of the small-breed subgroup between the PDH and control groups. No other perfusion variables differed between groups.
Conclusions and Clinical Relevance—Contrast-enhanced ultrasonography of the adrenal glands in dogs with PDH revealed a delayed TTP in the adrenal cortex and adrenal medulla, compared with values for control dogs. Contrast-enhanced ultrasonography was able to detect vascular changes induced by hyperadrenocorticism. Further studies are needed to evaluate whether reference ranges for clinically normal dogs and dogs with PDH can be determined and applied in clinical settings.
Abstract
Objective—To determine the detailed computed tomography (CT) anatomy of the metacarpophalangeal (MCP) joint in healthy horses.
Sample Population—10 cadaveric forelimbs from 10 adult horses without orthopedic disease.
Procedures—CT of the MCP joint was performed on 4 forelimbs. In 1 of the limbs, CT was also performed after intra-articular injection of 30 mL of contrast medium (40 mg of iodine/mL). Transverse slices 1-mm thick were obtained, and sagittal and dorsal planes were reformatted with a slice thickness of 2 mm. The CT images were matched with corresponding anatomic slices from 6 additional forelimbs.
Results—The third metacarpal bone, proximal sesamoid bones, and proximal phalanx could be clearly visualized. Common digital extensor tendon; accessory digital extensor tendon; lateral digital extensor tendon; superficial digital flexor tendon (including manica flexoria); deep digital flexor tendon; branches of the suspensory ligament (including its attachment); extensor branches of the suspensory ligament; collateral ligaments; straight, oblique, and cruciate distal sesamoidean ligaments; intersesamoidean ligament; annular ligament; and joint capsule could be seen. Collateral sesamoidean ligaments and short distal sesamoidean ligaments could be localized but not at all times clearly identified, whereas the metacarpointersesamoidean ligament could not be identified. The cartilage of the MCP joint could be assessed on the postcontrast sequence.
Conclusions and Clinical Relevance—CT of the equine MCP joint can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine MCP joint.
Abstract
Objective—To investigate the use of ultrasonography to assess nonunion of fractures in dogs and to compare results of ultrasonography, radiography, and histologic examination.
Sample Population—8 nonunion fractures in 6 dogs (1 each in 5 dogs and 3 in 1 dog); dogs ranged from 7 to 94 months of age and weighed 6 to 30 kg.
Procedures—Diagnostic assessment consisted of complete clinical and orthopedic examinations, radiography, B-mode (brightness mode) ultrasonography, and power Doppler ultrasonography. Biopsy samples were obtained during surgery for histologic examination. They were stained with H&E and immunolabeled by use of anti-CD31 antibodies. Correlations of power Doppler score, power Doppler count, vessel area, and radiographic prediction with the mean number of vessels counted per hpf were derived.
Results—Radiographically, 7 of 8 nonunion fractures were diagnosed as atrophic and were therefore estimated to be nonviable. Vascularity of nonunion fractures during power Doppler ultrasonography ranged from nonvascularized to highly vascularized. Absolute vessel count during histologic examination ranged from 0 to 63 vessels/hpf; 5 nonunion sites had a mean count of > 10 vessels/hpf. Vascularity during power Doppler ultrasonography was highly correlated with the number of vessels per hpf, whereas the correlation between the radiographic assessment and histologic evaluation was low.
Conclusions and Clinical Relevance—Radiographic prediction of the viability of nonunion fractures underestimated the histologically assessed vascularity of the tissue. Power Doppler ultrasonography provided a more accurate estimation of the viability of the tissue and therefore the necessity for debridement and autografts during revision surgery.
Abstract
Objective—To develop a practical ultrasonography-guided injection approach to anesthetic blockade of the femoral nerve in calves and to assess the method's accuracy.
Animals—13 cadavers of 4-week-old male Holstein Friesian calves.
Procedures—Detailed topographic and anatomic cross-sectional evaluation of the relevant topography in 3 cadavers was performed to identify optimal injection approaches to the femoral nerve. Three approaches (ventral paravertebral, dorsal paravertebral, and ileal) were evaluated by simulated ultrasonography-guided perineural injection of methylene blue dye in 10 cadavers. Ultrasonographic image quality, number of needle redirections required for correct needle positioning, and injection success as defined through a 3-point grading system were recorded.
Results—The dorsal paravertebral approach yielded the best results, compared with the ileal and ventral paravertebral approaches, to properly and adequately stain the targeted nerve.
Conclusions and Clinical Relevance—The dorsal paravertebral injection technique appeared to be the best choice for performing a femoral nerve block in calves, although this technique will need to be further evaluated in live calves to determine its effectiveness and clinical usefulness. Diagnostic perineural anesthesia of the femoral nerve in cattle might be helpful in identifying quadriceps muscle involvement in those with complex spastic paresis.
Abstract
Objective—To use computed tomography (CT) and magnetic resonance imaging (MRI) to provide a detailed description of the nasal cavities and paranasal sinuses in clinically normal mesaticephalic dogs.
Animals—2 clinically normal Belgian Shepherd Dogs that weighed 25 and 35 kg, respectively.
Procedure—The first dog was anesthetized and positioned in ventral recumbency for CT and MRI examinations, and transverse slices were obtained from the caudal part of the frontal sinuses to the nares. For MRI, T1-weighted, T2-weighted, and proton-density sequences were obtained. The second dog was anesthetized and positioned in dorsal recumbency with the head perpendicular to the table, and CT and MRI examinations were again conducted. At the completion of the MRI examination, each dog received an IV injection of heparin and then was euthanatized. A 4% solution of formaldehyde was perfused IV immediately after each dog was euthanatized. The skull was prepared, decalcified, embedded with gelatin, and sectioned into 5-mmthick sections by use of a stainless-steel knife. Each anatomic section was photographed and compared with the corresponding CT and MRI views.
Results—Structures on the CT and MRI views matched structures on the corresponding anatomic sections. The CT scans provided good anatomic detail of the bony tissues, and MRI scans were superior to CT scans for determining soft-tissue structures.
Conclusions and Clinical Relevance—CT and MRI provide a means for consistent evaluation of all structures of the nasal cavities and frontal sinuses. Both techniques could be useful for evaluation of diseases that affect the nasal region. (Am J Vet Res 2003;64:1093–1098)
Abstract
Objective—To determine magnetic resonance imaging (MRI) vertebral ratio values representing vertebral canal height, vertebral canal shape, and vertebral body shape in Doberman Pinschers with and without disk-associated cervical spondylomyelopathy (DACSM) and clinically normal English Foxhounds.
Animals—Doberman Pinschers with (n = 18) and without (20) DACSM and clinically normal English Foxhounds (18).
Procedures—All dogs underwent low-field MRI of the cervical vertebral column. From 5 specific measurements made at C3 through C7, 4 linear vertebral ratios were calculated and assessed for correlation: vertebral canal height-to-body height ratio (CBHR), vertebral canal height-to-body length ratio (CBLR), caudal canal height-to-cranial canal height ratio (CCHR), and vertebral body length-to-height ratio (BLHR). The CBHR and CBLR described vertebral canal height, CCHR described vertebral canal shape, and BLHR described vertebral body shape. A midvertebral canal-occupying ratio (mVCOR) for the spinal cord was calculated at C5.
Results—Compared with both groups of unaffected dogs, CBHR, CBLR, and BLHR for Doberman Pinschers with DACSM were significantly smaller. The C7 CCHR was significantly larger in DACSM-affected Doberman Pinschers, compared with clinically normal English Foxhounds. Ratios did not differ significantly between unaffected Doberman Pinschers and clinically normal English Foxhounds. Correlation coefficients between CBHR, CBLR, and mVCOR were low and not significant.
Conclusions and Clinical Relevance—Doberman Pinschers with DACSM had significantly smaller vertebral canal heights and more square-shaped vertebral bodies, compared with unaffected Doberman Pinschers, combined with a funnel-shaped vertebral canal at C7. Breed-specific differences were not evident. Linear MRI vertebral canal-to-body ratios do not appear to predict relative vertebral canal stenosis.
Abstract
Objective—To determine radiographic vertebral ratio values representing vertebral canal stenosis in Doberman Pinschers with and without clinical signs of caudal cervical spondylomyelopathy (CCSM).
Animals—Doberman Pinschers with (n = 81) and without (39) signs of CCSM.
Procedures—All dogs underwent lateral survey radiography of the cervical vertebral column. Five specific measurements were made at C3 through C7, and from those data, 3 ratios were calculated and analyzed for use in diagnosis of CSSM: canal height-to-vertebral body height ratio (CBHR), canal height-to-vertebral body length ratio (CBLR), and caudal vertebral canal height-to-cranial vertebral canal height ratio (CCHR). The CBHR and CBLR were considered indicators of vertebral canal stenosis, and CCHR described vertebral canal shape.
Results—Compared with Doberman Pinschers without CCSM, mean CBHR and CBLR values were significantly smaller for Doberman Pinschers with CCSM; for CBHR, this difference was evident at each assessed vertebra. The CCHR value for C7 was significantly larger in dogs with CCSM. Receiver operating characteristic statistics did not identify a threshold point that had combined high sensitivity and specificity sufficient to differentiate between Doberman Pinschers with and without CCSM.
Conclusions and Clinical Relevance—Doberman Pinschers with CCSM had vertebral canal stenosis combined with a funnel-shaped vertebral canal at C7 significantly more often than did Doberman Pinschers without CCSM. Despite these significant differences, no reliable threshold ratio values were identified to differentiate groups of dogs.
Abstract
Objective—To describe the contrast-enhanced ultrasonographic characteristics and vascular patterns of adrenal gland tumors in dogs and determine whether those features are indicative of malignancy or histologic type of tumor.
Animals—14 dogs with 16 adrenal gland lesions (10 carcinomas [8 dogs], 3 adenomas [3 dogs], and 3 pheochromocytomas [3 dogs]).
Procedures—Unsedated dogs with adrenal gland lesions underwent B-mode ultrasonography and contrast-enhanced ultrasonography ≤ 48 hours before adrenalectomy; contrast-enhanced ultrasonographic examinations were video-recorded. Macroscopic evaluation of the adrenal gland lesions and histologic examination of removed adrenal gland tissues were subsequently performed. Surgical and histopathologic findings and the ultrasonographic and contrast-enhanced ultrasonographic characteristics were recorded for the various tumor types. Time-intensity curves were generated from the contrast-enhanced ultrasonographic recordings and used to calculate regional blood volume (value proportional to area under the curve) and mean transit time (time the lesion began to enhance to the half-peak intensity).
Results—In adrenal gland carcinomas, tortuous feeding vessels were noticeable during the arterial and venous phases of contrast enhancement. Heterogeneity of contrast enhancement was evident only in malignant tumors. Compared with adenomas, adrenal gland carcinomas and pheochromocytomas had significantly less regional blood volume. Mean transit times were significantly shorter in adrenal gland carcinomas and pheochromocytomas than in adenomas.
Conclusions and Clinical Relevance—For dogs, evaluation of the vascular pattern and contrast-enhancement characteristics of adrenal gland tumors by means of contrast-enhanced ultrasonography may be useful in assessment of malignancy and tumor type.