Reliability of different radioisotopic techniques in diagnosing solitary hot spots in the spine of patients with malignant neoplasm.

INTRODUCTION Early diagnosis of spinal metastases is of key importance in further therapeutic management. OBJECTIVES The aim of the study was to assess the reliability of single-photon emission computed tomography (SPECT) or SPECT and computed tomography (SPECT/CT) in the diagnosis of solitary hot nodules in the spine identified by scintigraphy. PATIENTS AND METHODS In this retrospective study, 70 patients with neoplastic disease and a solitary nodule detected in the spine were analyzed. Using a SPECT/CT γ-camera, the type and site of the foci in the vertebra were analyzed. Bone scintigraphy, SPECT, and CT were performed. Reliability of the results was assessed depending on the applied technique. RESULTS In malignant lesions, increased isotope uptake was observed in the vertebral body with the posterior arch (89%), the body and both arches (67%), and the body alone (14%). In benign lesions, increased uptake was observed in the body area or in the joint area. Using SPECT, 25 of 27 cases (93%) of foci were properly classified as malignant. Using SPECT/CT, malignant lesions were observed in 26 of 27 cases (96%). Using SPECT, 19 of 43 cases were identified as benign (44%), and using SPECT/CT, 31 of 43 were identified as benign (72%). The agreement between SPECT and SPECT/CT was higher for malignant lesions (89%) than for benign lesions (67%). The use of CT in SPECT/CT examinations allowed to change the SPECT diagnosis of malignant lesions to that of benign lesions in 50% of the cases. CONCLUSIONS The criteria used in the diagnosis of solitary nodules in the spine direct the diagnosis largely towards noncancerous lesions. Reliability of positive assessment was significantly lower than that of negative one - 51% in SPECT and 68% in SPECT/CT. A hybrid SPECT/CT camera is more reliable than SPECT alone in the assessment of spinal lesions.