Background: Prostate cancer is one of the most common malignant tumours in men. It mostly occurs in elderly men, and most authors state that the average age of patients with prostate cancer is about 72 years Mortality from prostate cancer is usually the result of the advanced disease. The metastasis of this cancer is a combination of lymphogen, hematogen and per continuitatem local spread. Objective: The aim of this study was to compare the detection of bone metastases by 99mTc-methylene diphosphonate (99mTc-MDP) planar whole bone scintigraphy (WBS) and pentavalent tehnetium 99m dimercaptosuccinic acid (99mTc DMSA (V)) in patients with advanced prostate cancer. Also, the aim was to assess to establish the value of 99mTc(V)-DMSA scintigraphy in the detection of metastatic bone lesions and compare the results to 99mTm-MDP bone scintigraphy. Methods: In a prospective study, MDP bone scintigraphy was performed in 40 patients with high-risk prostate cancer. Whole body planar scans were obtained at 3 h after injection of 740 MBq 99mTc MDP and 5 days later at similar times after injection of 555 MBq of 99mTc(V)DMSA. A qualitative as well as quantitative comparison was made between the (99)Tc(m) MDP bone scan and the (99)Tc(m)(V)DMSA scan in detection of osseous metastases. The reference methods used for discordant or equivocal lesions were correlative morphological imaging modalities, for example additional conventional radiography, CT or MRI. All scans were interpreted visually. Lesions were interpreted on each of the 4 modalities as normal, benign, equivocal, or malignant. Results: In 40 patient-based analysis, 18 patients had skeletal metastatic spread (45%) and 22 did not. Categorizing equivocal and malignant interpretation as suggestive for malignancy, the specificity of planar BS was 70%, and DMSA 55%Using the ROC test, DMSA was statistically more specific than planar MDP In lesion-based analysis, 18 lesions with increased uptake of DMSA were assessed. Conclusion: 99TcDMSA is a highly specific modality for detection of bone metastases in patients with high-risk prostate cancer. It is more specific than MDP alone and detection of bone metastases is improved by DMSA compared with planar BS.
Key words: Prostate cancer, bone scintigraphy, bone metastases.
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