Observer variability and sensitivity of radiographic diagnosis of canine medial coronoid disease.

OBJECTIVE: Medial coronoid disease (MCD) is a very common form of elbow joint disease and it's radiographic diagnosis can be challenging since it is frequently based on the detection of rather subtle primary or secondary changes than on a large primary lesion. We hypothesized that accuracy of radiographic diagnosis of MCD is highly dependent on training and experience level. METHODS: Radiographs of 102 canine elbows were evaluated for MCD by four observers with different levels of training and experience. All elbows underwent CT scans and arthroscopy. Sensitivity and specificity of radiographic and CT interpretation was determined using arthroscopy as a gold standard. Interobserver and intraobserver agreement (reliability and repeatability) were assessed by using Cohen's Kappa (κ) statistic. RESULTS: The sensitivity (92.4-96.7%) of the two experienced observers was almost comparable to that of CT (100%) and significantly higher than that of the two less experienced observers (77.2-80.4%). Reliability of the radiographic diagnosis of MCD was better between observers with higher experience level (κ= 0.74) than between observers of lower or different experience levels (κ=0.07-0.42). Repeatability was better in experienced (κ= 0.73-0.88) than in less experienced observers (κ= 0.31-0.42). CONCLUSION: Our results confirm that training and experience play important roles in reaching high sensitivity, reliability and repeatability for the radiographic diagnosis of MCD. CLINICAL RELEVANCE: Although radiography is inferior to CT in imaging of the medial coronoid process itself, sensitivity of radiographic diagnosis MCD can be significantly improved with observer experience almost reaching that of CT. Therefore, it is advised that radiographic screening for MCD should be performed by specialists experienced in the radiographic evaluation of elbow joint disease.

PET imaging of somatostatin receptors: design, synthesis and preclinical evaluation of a novel 18F-labelled, carbohydrated analogue of octreotide.

Because of the excellent nuclear properties of fluorine-18 and the growing interest in somatostatin receptor (sst) scintigraphy with PET, a novel carbohydrated (18)F-labelled sst ligand was developed and preclinically evaluated. Synthesis of N(alpha)-(1-deoxy- D-fructosyl)- N(epsilon)-(2-[(18)F]fluoropropionyl)-Lys(0)-Tyr(3)-octreotate ([(18)F]FP-Gluc-TOCA) was completed in approximately 3 h (20%-30% yield). [(19)F]FP-Gluc-TOCA showed no affinity to hsst1 and hsst3, moderate affinity to hsst4 (IC(50): 437+/-84 n M) and hsst5 (IC(50): 123+/-8.8 n M) and very high affinity to hsst2 (IC(50): 2.8+/-0.4 n M). As a result of carbohydration, lipophilicity of [(18)F]FP-Gluc-TOCA was found to be low (lg P(OW)=-1.70+/-0.02). In mice, the tracer was rapidly cleared via renal excretion (kidneys: 8.69%+/-1.09%ID/g) and showed low uptake in liver (0.72%+/-0.14%ID/g) and intestine (1.88%+/-0.52%ID/g) and high tumour uptake (13.54%+/-1.47%ID/g) (all data at 1 h p.i.). Tumour to non-tumour ratios at 60 min p.i. reached 25, 19, 7, 1.6 and 56 for blood, liver, intestine, kidney and muscle, respectively. A similar biodistribution pattern was observed in pancreatic tumour-bearing rats. Tumour uptake in rats was reduced to 36% and 18% of control (30 and 60 min) by co-injection of 500 microg Tyr(3)-octreotide, demonstrating sst-specific uptake. In a first [(18)F]FP-Gluc-TOCA-PET study of a patient with a metastatic carcinoid in the liver the tracer showed superior pharmacokinetics, e.g. rapid urinary excretion and low uptake in liver, kidney and spleen. Multiple liver lesions (SUVs ranging from 21.4 to 38.0) and previously unknown focal uptake in the abdomen (SUV 10.0) were clearly visible. This is the first report on PET imaging using an (18)F-labelled sst binding peptide; it indicates that [(18)F]FP-Gluc-TOCA offers excellent imaging characteristics and allows sst imaging with high tumour to non-tumour contrast.