Planar versus SPET imaging in the assessment of condylar growth

The aim of this study was to compare two methods of quantifying Tc-99(m)-me thylene diphosphonate uptake in the mandibular condyle. The study groups co nsisted of 23 patients with mandibular asymmetry and 16 normal volunteers a ged 10-30 years. The accuracy and reproducibility of SPET using condyle-to- clivus ratios was compared with planar analysis using condyle-to-L4 (fourth lumbar vertebra) ratios. Quantitative analysis was correlated with semi-qu antitative grading by three observers. Normal ranges for condyle-to-L4 and condyle-to-clivus ratios in individuals aged 11 years or over were determin ed. These ratios are useful in the serial monitoring of patients with condy lar hyperplasia to establish when condylar growth has ceased and hence the type of surgery performed. Visual interpretation of condylar activity shoul d use a combination of planar and SPET images and be performed in conjuncti on with quantitative analysis. Semi-quantitative grading on SPET images det ected more subtle differences in condylar activity than planar images (usin g quantitative analysis as a standard). ((C) 2000 Lippincott Williams & Wil kins).