Comparison Between 99mTc-MDP and 18F-NaF is in Diagnosis in Bone Metastases.
Abstract
Imaging techniques such as CT and MRI as well as bone scan interrogate are common methods used for evaluation of metastatic bone lesions. However, the sensitivity of skeletal scanning in diagnosing bone metastases is remarkably high, exceeding 90 %. Also, it is used most commonly based on its effectiveness, low cost, widespread availability and favourable dosimetry. On the other hand, the specificity is rather low, however the specificity rates have improved since the introduction of hybrid cameras that make it possible to combine physiological and anatomical information together (SPECT/CT) (1) . Also, the spatial resolution of bone scintigraphy is poor measuring approximately 1 cm and can result in difficulty determining the precise location of a lesion within a bone which can be of diagnostic significance (2) . 18 F-labelled sodium fluoride (NaF) is an osteotropic compound used in positron emission tomography (PET) which has a higher first pass extraction rate than 99m Tc-MDP which is on average approximately three times higher in metastatic lesions than in adjacent normal bone tissue. Consequently, 18 F-NaF has very high selectivity for bone metastases, however its relatively low specificity when not used in conjunction with morphological imaging techniques and the requirement of a cyclotron for production are limiting factors in its use (2) .