Use of bisecting angle techniques in veterinary orthopaedic radiography

Problems encountered in veterinary orthopaedic radiography include difficulties obtaining optimally positioned radiographs. In these situations, compromise radiographic projections are used to obtain the necessary clinical information. Results of investigations into the use of bisecting angle radiographic techniques for imaging canine long bones are presented. Comparisons are made between radiographs made using ideal positioning and using three different compromise techniques, including bisecting angle projections. The use of bisecting angle techniques in a series of ten clinical cases is also discussed. A study into the radiographic images obtained of canine femora and humeri using an ideal projection technique (with the long axis of the bone parallel to the cassette) and using three techniques when the bone was at an angle to the cassette (beam perpendicular to cassette, beam perpendicular to bone and bisecting projection) demonstrated that the ideal radiographic technique gave the most accurate image of the bone in terms of reproduction of size and proportions. However, of the three angled techniques, the bisecting angle projection gave the most accurate reproduction of proportions at all bone-cassette angles. All angled projections created a size distortion, and at lower bone-cassette angles, this was lowest when the primary X-ray beam was perpendicular to the cassette. At higher bone-cassette angles, this projection was no more accurate at reproducing bone size than the bisecting projection. A subjective assessment demonstrated that maintenance of the radiographic appearance of the trabecular bony detail was best with the ideal projection, followed by the angled projection with the tube perpendicular to the cassette. In 10 clinical cases, where the required information (e.g. implant placement or post-operative progression) could not be adequately obtained from standard radiographic projections, use of the bisecting angle technique allowed the area of interest to be examined more completely. Use of bisecting angle techniques for veterinary orthopaedic investigations could be considered where optimal positioning for radiography is not possible

Effect of osteoarthritis on the repeatability of patella tendon angle measurement in dogs

Objective: To evaluate the influence of osteoarthritis on the measurement of patella tendon angle (PTA) and determine intraobserver and interobserver variability. Study design: Retrospective clinical study. Sample population: Eighty‐seven mediolateral radiographs that were obtained prior to tibial tuberosity advancement. Methods: Radiographic osteoarthritis was scored by 2 observers using guidelines derived from the International Elbow Working Group Protocol. Patella tendon angle was measured by 3 observers on 3 occasions, with at least 7 days between measurements. The data were statistically analyzed via weighted κ and Kruskal‐Wallis testing. Results: A fair strength of agreement was found among observers scoring osteoarthritis, with the same grades in 48% of radiographs. The intraobserver average bias between PTA measurements 1 and 3 ranged from −0.38° to −0.94°. Interobserver bias in angle measurement ranged from −0.92° to −2.00°. Observer 1 had the narrowest range of PTA differences (12.1°), and observer 3 had the highest range of PTA differences (23.5°). Observer 2 had the lowest mean bias (−0.38°). The mean bias was lowest between observers 1 and 2 (−0.92°) and highest between observers 1 and 3 (−2.0°). The mean intraobserver standard deviation of the PTA measurement differences was 2.90°, and interobserver standard deviation of the PTA measurement differences was 2.26°. The degree of osteoarthritis did not influence PTA measurements or their variability. Conclusion: The current study did not find evidence of an influence of osteoarthritis on PTA or on the repeatability of measurements. Clinical significance: Our findings suggest that osteoarthritis should not affect the radiographic planning for tibial tuberosity advancement surgery. The high variances in PTA measurement in less experienced observers may influence the clinical outcome of surgery

One-parametric optimization: jumps in the set of generalized critical points

We consider a one-parametric finite-dimensional optimization problem P(t) whose describing functions are three times continuously differentiable and belong to the generic subset F introduced by Jongen/Jonker/Twilt. We construct feasible descent directions - so-called jumps - at bifurcation and turing points of the set of generalized critical points C of P(t). (In former papers such jumps have already been constructed for the special case that the considered point is an endpoint of a branch consisting of local minimizers.). By using these jumps together with pathfollowing methods several connected components of C can be followed in order to compute solution points of P(t) (e.g. stationary points or local minimizers) for finitely many parameter values t in a given interval. (orig./RWE)SIGLEAvailable from TIB Hannover: RO 7722(482) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman

Evaluation of radiographs for the detection of sublumbar lymphadenopathy in dogs

The purpose of this study was to evaluate radiographs for the detection of sublumbar lymph node (SLN) enlargement. Ultrasound was used to determine SLN size. Twenty-two dogs with anal gland adenocarcinoma or lymphoma were prospectively included, with 16/22 having SLN enlargement on ultrasound. Twenty-one dogs without enlargement were retrospectively included as controls. Three blinded observers evaluated 43 right lateral abdominal radiographs for the presence of SLN enlargement. Sensitivity and specificity of radiographs for the detection of SLN enlargement were 81%/70%, 94%/81%, and 75%/100% for a general practitioner, imaging resident, and radiologist, respectively. Ventral displacement of the colon, a soft tissue opacity in the caudal retroperitoneal space and loss of conspicuity of the ventral margin of the iliopsoas muscle were radiographic findings significantly associated with identification ( -values < 0.05). Markedly enlarged SLNs (> 21.5 mm) were consistently detected radiographically by observers with specialist imaging training. Key clinical message: Radiographic visualization should raise suspicion of neoplastic infiltration of SLN but lack of visualization does not exclude mild to moderate enlargement. Additional imaging such as ultrasound or computed tomography remains important to confirm or exclude sublumbar lymphadenopathy

Paraneoplastic hypercalcemia in a canine patient with a mandibular salivary carcinoma

OBJECTIVE: To describe a novel presentation of paraneoplastic hypercalcemia caused by a canine salivary carcinoma. ANIMAL: A 6-year-old intact male Husky with hypercalcemia and a spontaneous salivary carcinoma, stage III. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The dog presented with polyuria, polydipsia, and hypercalcemia. Physical examination revealed a 37 X 43-mm firm mass in the ventrolateral aspect of the right-hand side of the neck, caudal to the temporomandibular joint. Incisional biopsy was suspicious of metastatic carcinoma to the mandibular lymph node. A full-body CT scan found a large, heterogenous, contrast-enhancing mass on the right ventrolateral neck that appeared to be originating from either the mandibular lymph node or right mandibular salivary gland. Parathyroid hormone–related protein was considered within normal reference intervals, and both parathyroid glands appeared ultrasonographically normal. TREATMENT AND OUTCOME: The patient was treated with a marginal surgical excision of the mass, without immediate complications. Histopathology confirmed the presence of a salivary carcinoma with narrow margins of excision and invasion of the mandibular lymph node. Twenty-four hours after surgery, ionized calcium returned to normal reference values and clinical signs completely resolved. CLINICAL RELEVANCE: Hypercalcemia is an urgent pathology with important systemic implications requiring prompt diagnosis and intervention. In this case report, we identify the first salivary carcinoma associated with a paraneoplastic hypercalcemia, including this pathology as a new differential diagnosis. The hypercalcemia resolved with marginal surgical excision, but interestingly the parathyroid hormone–related protein was not overexpressed, meaning that this neoplasia could mediate hypercalcemia by another pathophysiological mechanism