Technetium-99m-sestaMIBI scintigraphy in multiple myeloma and related gammopathies: a useful tool for the identification and follow-up of myeloma bone disease

Background and Objectives. Technetium-99m 2-methoxyisobutyl-isonitrile (Tc- 99m-sestamibi) has recently been proposed as a potential tracer in patients with multiple myeloma (MM), as its increased uptake in the bone marrow has been reported as indicator of myeloma activity. We evaluated the role of T c-99m-sestamibi scintigraphy in the detection of myeloma bone disease in MM and related gammopathies, and also assessed its relationship with clinical status and stage of the disease, focusing in particular on the early follo w-up of a smalt series of MM patients treated with high-dose therapy. Design and methods. Forty-six consecutive patients affected by MM or monocl onal gammopathy of undefined significance (MGUS) were studied by whole body scans obtained 20 minutes after administration of 740 MBq of Tc-99m-sestam ibi. A semiquantitative uptake score was used and scintigraphic findings we re correlated with clinical and laboratory data. Results. All the MGUS patients showed a negative Tc99m--sestamibi scan. Amo ng the 32 MM patients (25 with active disease and 7 in clinical remission) 24 showed a positive scan, while 8 presented only a physiologic uptake of t he tracer. The uptake score correlated significantly with all the mast rele vant clinical variables. in the follow-up of 8 MM patients treated with hig h-dose chemotherapy Tc-99m-sestamibi closely paralleled the activity of mye loma bone disease. Comparison with X-ray skeletal survey showed discordant results in 14 out of the overall 56 scans obtained (27%), with 10 cases of negative Tc-99m-sestamibi scans but lytic bone lesions revealed by X-ray (7 of them were in clinical remission), and 4 negative X-ray surveys in patie nts with positive Tc-99m-sestamibi scans. Overall sensitivity and specifici ty of Tc-99m-sestamibi scintigraphy in detecting myeloma bone disease were 90% and 88%, respectively. Interpretation and Conclusions. This study provides additional evidence ind icating that Tc-99m-sestamibi scintigraphy closely reflects myeloma disease activity in bone marrow, with very high sensitivity and specificity, Tc-99 m-sestamibi scintigraphy is therefore suggested as a reliable new tool for the staging and follow-up of myeloma bone disease. (C) 2001, Fenata Storti Foundation.