An experience of using combined radionuclide and x-ray examination to find bone system pathologies
The objective. Evaluation of the possibilities of x-ray computed tomography (CT) combined with single photon emission computed tomography (SPECT-CT) in finding a cause of pathological accumulation of a radiopharmaceutical (RP) in a solitary spot according to the findings of planar osteoscintigraphy in oncologic patients. Patients and methods. The study included 56 patients (25 males, 31 females, average age 55.5 ± 2.5 years) with diagnosed oncologic disease (cancer of mammary gland – 58%, prostate cancer – 39%, kidney cancer – 3%), in whom, according to the findings of planar osteoscintigraphy performed to find secondary changes in the bone system, solitary spots of pathological RP accumulation were found (in vertebrae in 58% of patients, in ribs – in 33%, in pelvic bones – in 9%). All patients underwent hybrid SPECT-CT imaging in the area of the spot. Results. The results of the present work have demonstrated a high specificity of CT imaging in detection of benign changes in bone tissue in the projection of a solitary RP accumulation spot –fractures and degenerative-dystrophic changes were found on the whole in 36% of patients. In finding additional spots of enhanced RP accumulation according to SPECT (14%), bone lesion was assessed as multiple, therefore, metastatic- the results of hybrid SPECT-CT imaging did not influence the final conclusion. In 31% of cases, SPECT-CT findings confirmed solitary lesion in bone structures with the signs of the metastatic character of changes obtained by CT. In 19% of cases, changes in the bone tissue were absent in the projection of a RP hyperfixation spot according to CT. Despite this, specialists assessed these spots as metastatic, which was confirmed by the disappearance or decrease of the intensity of the enhanced RP accumulation spot under the influence of local or systemic treatment with dynamic observation. The average size of spots was 1.71 ± 0.21 cm. Sensitivity and specificity for the SPECT component was 91 and 31%, respectively- sensitivity and specificity for the CT component – 52 and 92%. On the whole, hybrid SPECT-CT imaging of solitary RP accumulation spots in the bone system demonstrated the accuracy of 92%, sensitivity – 91%, specificity – 92%. Conclusion. The optimal use of SPECT-CT in the area of a solitary RP accumulation spot enhances the possibilities of planar osteoscintigraphy to detect additional spots of pathological RP accumulation and permits to precisely determine their localization and nature.