Evaluation of bone metastatic burden by bone SPECT/CT in metastatic prostate cancer patients: defining threshold value for total bone uptake and assessment in radium-223 treated patients

Abstract

ObjectivesTo establish a new three-dimensional quantitative evaluation method for bone metastasis, we applied bone single photon emission tomography with computed tomography (SPECT/CT). The total bone uptake (TBU), which measures active bone metastatic burden, was calculated as the sum of [mean uptake obtained as standardized uptake value (SUV) above a cut-off level] × (the volume of the lesion) in the trunk using bone SPECT/CT. We studied the threshold value and utility of TBU in prostate cancer patients treated with radium-223 (Ra-223) therapy.MethodsTo establish the threshold value of TBU, we compared bone metastatic and non-metastatic regions in 61 prostate cancer patients with bone metastasis and 69 without. Five fixed sites in each patient were selected as evaluation points and divided into bone metastatic and non-metastatic sites. Sensitivity and specificity analysis was applied to establish the threshold level. Using the obtained threshold value, we then calculated the TBU in nine prostate cancer patients who received Ra-223 therapy, and compared the results with the bone scan index (BSI) by BONENAVI® and visual evaluation of bone scintigraphy.ResultsUptake was significantly lower in non-metastatic sites in patients with bone metastasis than in patients without metastasis. Sensitivity and specificity analysis revealed SUV = 7.0 as the threshold level. There was a discrepancy between TBU and BSI change in two of the nine patients, in whom TBU change correlated with visual judgement, but BSI change did not. In two patients, BSI was nearly 0 throughout the course, but the TBU was positive and changed, although the change was not large. These results suggest that TBU may be more accurate and sensitive than BSI for quantitative evaluation of active bone metastatic burden.ConclusionWe established a threshold value (SUV > 7.0) for three-dimensional TBU for evaluating active bone metastatic burden in prostate cancer patients using bone SPECT/CT. Despite the small number of patients, we expect the change in TBU could be more accurate and sensitive than the change in BSI among patients who received Ra-223.

Quantitative Bone SPECT/CT: High Specificity for Identification of Prostate Cancer Bone Metastases

“…SUVs were further higher in our study than those reported by Umeda et al, who found a lower threshold of 7 g/mL of SUV max , above which the tumor burden of metastatic prostate cancer patients was determined [9]. Kuji et al reported a high accuracy of quantitative SPECT/CT for the diagnosis of bone metastases in 170 prostate cancer patients [10].…”

Dynamic changes of bone metastasis predict bone‐predominant status to benefit from radium‐223 dichloride for patients with castration‐resistant prostate cancer

“…Then the average SUVpeak was obtained as the average of the peaks of the regional SUV. 11 When osteosclerotic lesions on bone superscans extended on CT and SUVpeak increased on bone SPECT/CT, the dynamic changes of bone metastases were classified as the new progressive lesions group. When osteosclerotic lesions on bone superscans extended without a SUVpeak increase, or osteosclerotic lesions reduced regardless of SUVpeak changes, the dynamic changes of bone metastases were classified into the only known lesions group.…”

Assessment of Skeletal Tumor Load in Metastasized Castration-Resistant Prostate Cancer Patients: A Review of Available Methods and an Overview on Future Perspectives

“…Most single-institution studies (n = 9/25, 36%) originated from the United States; moreover, most of the multi-institutional studies included an American center (n = 6/9, 67%) [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Five studies originated from Germany [ 23 , 24 , 25 , 26 , 27 ], four from Sweden [ 28 , 29 , 30 , 31 ], and six from Japan [ 32 , 33 , 34 , 35 , 36 , 37 ]. Information about patient number, acquisition technique, type of employed isotope (when applicable) and method of computational analysis were obtainable from all studies.…”

“…Lastly, a recent work by Umeda et al used quantitative SPECT to establish a SUV threshold, which was used to discriminate metastases from degenerative changes and to compute a “total bone uptake” as a measure of tumor burden [ 37 ]. This value was compared to BSI and resulted slightly more efficient in assessing presence of disease a therapy response.…”