Comparison of four methods for quantitative assessment of 99mTc-MDP SPECT in patients with suspected condylar hyperplasia. / Comparación de cuatro métodos de valoración cuantitativa de la SPECT con 99mTc-MDP en pacientes con sospecha clínica de hiperplasia condilar.

OBJECTIVE: To compare variability, reproducibility and repeatability of four quantitative evaluation methods to interpret the 99mTc-MDP SPECT reports in patients with clinically suspected unilateral condylar hyperplasia. METHOD: This was a descriptive observational study carried out with SPECT images of 38 patients with clinical and radiographic signs of unilateral condylar hyperplasia, and interpreted using four quantitative methods: 1) one image, variable-size region of interest (ROI); 2) one image, fixed-size ROI (1.76cm2), 3) five image variable-size ROI; 4) five image, fixed-size ROI (1.76cm2). Each of the images was reported simultaneously (but in an independent way) by two nuclear medicine experts, in both total radioactive counts as well as normalized counts to evaluate the reproducibility (inter-operator variability) and the repeatability (intra-operator variability). RESULTS: Higher reproducibility and repeatability were obtained in 5-image fixed-size ROI method (intra-class correlation coefficient: 0.979 [0.959; 0.989]). A high grade of diagnostic agreement (97.4%) was also attained in fixed methods (Kappa 0.940, p value: .000) from either total or normalized counts. There was no difference between fixed-size 1 vs 5 image methods. The methods based on variable-size ROI had a low grade of agreement (Kappa<0.20). More positive cases were identified using one image, ROI variable total counts (27 cases), but when the counts were normalized, they presented a lower number (5 cases). CONCLUSION: Five-image fixed-size ROI provides the best intra-operator and inter-operator reliability for the diagnosis of unilateral condylar hyperplasia. In the four methods using normalized counts fewer positive cases were detected (≥10%), unlike with total counts when more positive cases were found.

Comparison of 99mTc-MDP SPECT qualitative vs quantitative results in patients with suspected condylar hyperplasia. / Comparación de resultados cualitativos vs. cuantitativos de 99mTc-MDP SPECT en pacientes con sospecha clínica de hiperplasia condilar.

OBJECTIVE: To compare qualitative vs quantitative results of Single Photon Emission Computerised Tomography (SPECT), calculated from percentage of 99mTc-MDP (methylene diphosphonate) uptake, in condyles of patients with a presumptive clinical diagnosis of condylar hyperplasia. MATERIALS AND METHOD: A retrospective, descriptive study was conducted on the 99mTc-MDP SPECT bone scintigraphy reports from 51 patients, with clinical impression of facial asymmetry related to condylar hyperplasia referred by their specialist in orthodontics or maxillofacial surgery, to a nuclear medicine department in order to take this type of test. Quantitative data from 99mTc-MDP condylar uptake of each were obtained and compared with qualitative image interpretation reported by a nuclear medicine expert. RESULTS: The concordances between the 51 qualitative and quantitative reports results was established. The total sample included 32 women (63%) and 19 men (37%). The patient age range was 13-45 years (21±8 years). According to qualitative reports, 19 patients were positive for right side condylar hyperplasia, 12 for left side condylar hyperplasia, with 8 bilateral, and 12 negative. The quantitative reports diagnosed 16 positives for right side condylar hyperplasia, 10 for left side condylar hyperplasia, and 25 negatives. CONCLUSIONS: Nuclear medicine images are an important diagnostic tool, but the qualitative interpretation of the images is not as reliable as the quantitative calculation. The agreement between the two types of report is low (39.2%, Kappa=0.13; P>.2). The main limitation of quantitative reports is that they do not register bilateral condylar hyperplasia cases.