RECEIVER OPERATING CHARACTERISTIC CURVE ANALYSIS OF THE UTILITY OF THORACIC RADIOGRAPHS FOR THE DIAGNOSIS OF FELINE CARDIAC DISEASE

The results of a retrospective study in which 90 sets of feline thoracic radiographs were examined by six readers were evaluated with the aid of receiver operating characteristic (ROC) curve analysis. There were 51 sets of radiographs of 45 normal cats and 39 sets of radiographs of 33 cats with cardiac disease. The readers were asked to classify each set of radiographs as normal or abnormal, with respect to cardiac disease, into one of five diagnostic cholces that reflected reader confidence. The method of generating an ROC curve is discussed. There was no significant difference in the accuracy of interpretation between the five experienced readers. The mean accuracy of this group was 91%. However, inspection of the individual ROC curves demonstrated a fundamental difference in underlying reader bias (i.e., over-or underreading). As expected, the experienced readers were statistically more accurate than an inexperienced reader. ROC curve methodology has potential applications in veterinary medicine not only for assessing observer performance and reader bias, but also for comparing tests and in clinical decision making.     

SENSITIVITY OF RADIOGRAPHIC DETECTION OF LUNG METASTASES IN THE DOG

Thoracic radiographs were taken in right lateral recumbent (RLR), left lateral recumbent (LLR), and ventrodorsal (VD) projections in 80 dogs with known or suspected malignant tumors. Radiographs in each projection were interpreted, independently of those in the other two projections, by four veterinary radiologists, and classified as positive or negative for one or more lung metastases. The four radiologists then met, to agree on a diagnosis for each patient by simultaneously reviewing all three views. This panel diagnosis became the standard for subsequently classifying individual views as either true positive or true negative. As determined by a consensus of the panel, 25 dogs had at least one positive thoracic radiograph.
The three radiographic projections differed in sensitivity for the detection of lung metastases. In this study, the RLR view was the most sensitive, and the VD view the least sensitive. The sensitivity of detection improved significantly with multiple readers. From these data we recommend that, for detection of lung metastases in the dog, the RLR view be included in any diagnostic protocol; a minimum of two readers be used; and a three-view protocol be used if only one reader is available.     

RADIOGRAPHIC AND ULTRASONOGRAPHIC EVALUATION OF THE PATELLAR LIGAMENT FOLLOWING TIBIAL PLATEAU LEVELING OSTEOTOMY

Objective evaluation of patellar ligament changes following tibial plateau leveling osteotomy (TPLO) for cranial cruciate ligament injury has not been published to date. In this study, the patellar ligament was evaluated using radiographs and high-resolution ultrasound in 31 stifles (29 dogs) preoperatively and at 1 month (n=31), 2 months (n=18), and 6 months (n=13) postTPLO. A ratio of the thickness of the proximal to distal patellar ligament was determined for all radiographs evaluated. Ultrasound evaluation included proximal, middle, and distal mid-sagittal thickness and transverse thickness, and transverse area measurements. Subjective grading (0 being normal through a scale of 3) of the ultrasound changes was also performed at each evaluation. Significant thickening of the distal patellar ligament was noted postoperatively as evidenced by thickness and area measurements and a decreased radiographic ratio (P < 0.01). Preoperative patellar ligament thickness and area were similar at the proximal, middle and distal sites. Ultrasound-derived thickness and area measurements of the distal patellar ligament were increased at 1 and 2 months (P < 0.01). The radiographic ratio was significantly decreased at 1, 2 and 6 months (P < 0.01). Subjectively, all patellar ligaments scored a 0 preoperatively and 16/31 received a score of 2 or 3 during follow-up evaluation. Additionally, these dogs had ultrasonographic and radiographic changes consistent with distal patellar ligament thickening. Body weight (kg) and postoperative TPLO angle had a significant influence on 1-month postoperative distal patellar ligament area using a stepwise logistic model (P < 0.05). Patellar ligament desmitis is a common postoperative sequela to the TPLO procedure, however its clinical significance (i.e., correlation with a residual lameness) was not evaluated in this study.     

Regional Economic Diversity and Diversification

ABSTRACT Regional scientists have long attempted to develop meaningful definitions and measures of economic diversity and diversification, and to establish functional relationships between diversity, diversification, and economic performance. The multiplicity of definitions and measures explains, in part, the confusion about these relationships. A framework that sorts out the overlaps, contradictions, and gaps of the various definitions and measures IS needed. Such a framework would explicitly address the question, “What is the relationship between a region's changing economic structure and performance?” In this paper it is suggested that an input-output model that incorporates elements of portfolio theory be used as the integrating framework for analysis.     

Descriptive Histomorphometric Ingrowth Analysis of the Zurich Cementless Canine Total Hip Acetabular Component

Objectives— To (1) determine bone contact with the outer surface and ingrowth into the perforated outer shell of the Kyon acetabular component at 2, 6, and 12 months after total hip replacement (THR) and (2) determine correlation between radiographic lucency surrounding the cup–bone interface and bone contact and ingrowth.
Study Design— Experimental study.
Animals— Large breed dogs (n=11) with and without hip dysplasia.
Methods— Force platform gait analysis was performed preoperatively and 2, 6, and 12 months after THR. Curvilinear length of lucency (CLL) was measured on pelvic radiographs. Tissue contact with the outer cup and ingrowth into the cup were determined histomorphometrically at 2, 6, and 12 months.
Results— Peak vertical force and vertical impulse of the treated and control hind limb were not significantly different at any time. Median bone contact with the outer cup surface was 77%, 48%, and 76% at 2, 6, and 12 months, respectively. Median bone ingrowth into the cup perforations was 50%, 20%, and 44% at 2, 6, and 12 months, respectively. Median bone ingrowth to the inner cup surface was minimal at any time. CLL did not correlate with bone ingrowth.
Conclusions— Bone ingrowth into cup perforations occurred in each dog and was already present 2 months after THR, but most of the inner cup space remained vacant.
Clinical Relevance— Radiographic lucency surrounding the cup–bone interface does not allow assessment of bone contact with the outer surface or bone ingrowth into the Kyon cup in dogs without clinical problems.     

Life Threatening Complication Associated with Anesthesia in a Dog with Masticatory Muscle Myositis

Objective— To report a serious complication in a dog with masticatory muscle myositis (MMM) that occurred during general anesthesia for diagnostic testing.
Study Design— Case report.
Animals— A 2-year-old male Pug.
Methods— MMM was diagnosed in a Pug with a 2-week history of trismus by electrodiagnostics, histopathology, and 2M antibody test. During anesthesia tongue protrusion occurred and because of trismus, an inability to reposition the tongue resulted in venous congestion and severe swelling. Forceful physical attempts and subsequent removal of the rostral digastricus and masseter muscle attachments from the mandible did not increase jaw mobility. Mandibular symphysiotomy was necessary to resolve lingual venous congestion and to reposition the tongue into the oral cavity.
Results— Tongue swelling rapidly subsided after symphysiotomy allowing the tongue to be repositioned into the oral cavity. After treatment of MMM with corticosteroids, jaw range of motion improved and at 6 months was ∼70% normal.
Conclusions— Trismus could not be overcome by detachment of the masseter and digastricus muscle insertions from the mandible, and symphysiotomy was required to reposition the tongue in the oral cavity.  

Clinical Relevance—

In dogs with MMM, tongue position should be monitored during anesthesia to avoid inadvertent protrusion and swelling from venous congestion. Use of anesthetic monitoring equipment on the tongue, such as a pulse oximeter probe, should be avoided in these patients.     

Interobserver Repeatability of Measurements on Computed Tomography Images of Lax Canine Hip Joints from Youth to Maturity

Objectives— To determine interobserver repeatability of measurements on computed tomography (CT) images of lax canine hip joints at different ages and in the presence of degenerative joint disease at maturity. Study Design— Longitudinal observational investigation. Animals— Sibling crossbreed hounds. Methods— Pelvic CT was performed at 20, 24, 32, 48, 68, and 104 weeks of age. Measures were performed on 3 contiguous two‐dimensional (2D) transverse CT images of both hips at each time point by 3 investigators. Center‐edge angle (CEA), horizontal toit externe angle (HTEA), ventral (VASA), dorsal (DASA), and horizontal (HASA) acetabular sector angles, acetabular index (AI), and percent femoral head coverage (CPC) were measured. Interobserver repeatability was quantified with the intraclass correlation coefficient (ICC). Satisfactory repeatability was considered when ICC≥0.75. Results— DASA, CEA, and CPC were repeatable in all age groups. HASA and HTEA were repeatable for all but 1 time point. At 20 weeks of age, all measures but AI were repeatable, and at 104 weeks of age, DASA, CEA, CPC, and HASA were repeatable. Measures were repeatable in hips with and without degenerative changes with the exceptions of AI and HASA in normal hips and VASA and HTEA in osteoarthritic hips. Conclusions— Most 2D CT measurements examined were repeatable regardless of age or joint disease. Clinical Relevance— Two‐dimensional CT measures may augment current techniques for assessing joint changes in lax canine hips.