Osteoscintigraphy and SPECT/CT in the Diagnosis of Various Variants of Bone Metastases
Authors: Рыжков А. , Ryzhkov A. , Крылов А. , Krylov A. , Блудов А. , Bludov A. , Ширяев С. , Shiryaev S. 
Published: April 2018

Purpose: To determine the diagnostic capabilities of body scan (BS) and SPECT/CT in the diagnosis of various variants of bone metastases (BM). Material and methods: The data of 37 patients with BM of breast cancer (20 patients), prostate cancer (7 patients) and other tumors various localization (10 patients) were analyzed. The study was carried out in two stages: first, BS was performed, 3 hours after intravenous introduction of an osteotropic radiopharmaceutical labeled with 99mTc (technephor or phosphotech), followed by SPECT/CT of the selected zone of interest. All studies were performed on a combined system Symbia T2 (Siemens) with a 2-slice low dose CT. Results: With BS the foci of the tumor lesion were identified in 33 cases, and in SPECT/CT in 37 cases. There were detected 159 BM (21 sites: 0.4–0.9, 59 sites: 1.0–1.9, 79 sited: 2.0–4.5 cm). The total detectable incidence of metastases with BS was 66.0 % (105 BM) of all metastases detected in comparison with SPECT/CT (159 BM). Detectability with BS increased with increasing size of detectable foci. Foci less than 1 cm are detected in isolated case (1 from 21 cases). Metastases measuring from 1 cm to 1.9 cm are detected only in 52.5 % of cases (31 from 59 cases). The detectability of large metastases (2 cm or more) with BS (92.4 %) approaches the SPECT/CT (100 %) – 73 from 79 cases. There were detected with BS 27 osteoblastic BM in comparison 56 BM with SPECT/CT (48.2 %). The detectability with BS of mixed BM (76.3 %) and octeolitic BM (75.4 %) showed no differences. Firstly it can be explained by a predominance of smaller osteoblastic foci, and secondly reparative processes in metastases, accompanied by reduction of the radiopharmaceutical. The correction of the conclusion of the BS was required just in 24 cases: in 8 cases, when the BS was marked overdiagnosis, 16 – underdiagnosis. However, BS does not lose its value as a screening. In one case, even if BS has been revealed metastasis, it is not yet accompanied by destruction of bone tissue. Despite such significant differences in diagnostic accuracy of BS and SPECT/CT, BS proved to be uninformative only in 2 cases: when undetected metastases without primary tumor identified, and in the case of the screening of metastasis the accumulation of the radiopharmaceutical in the bladder. In 2 other cases, the lack of accumulation of the radiopharmaceutical was determined by the reparation that can only be considered conditionally uninformative. However, SPECT/CT shows clear advantages in the visualization of bone metastases due to computed tomography, allowing to estimate the structure of bone tissue. In 9 cases even to SPECT-slices metastases were not accompanied by pathological accumulation of the radiopharmaceutical. Conclusion: SPECT/CT is a highly informative method for detecting bone metastases, the use of which allows reducing the time of examination and dose irradiation of patients due to the rejection of additional radiological procedures. In addition, SPECT/CT at the same time allows differential diagnosis of structural and metabolic bone changes, which increases both the accuracy of primary diagnosis and control of treatment.