Multiple Myeloma: Molecular Imaging with 11C-Methionine PET/CT--Initial Experience

Area of Science:

• Nuclear Medicine
• Oncology
• Radiochemistry

Background:

• Multiple myeloma (MM) is a hematologic malignancy characterized by malignant plasma cells in the bone marrow.
• Accurate staging and assessment of disease activity are crucial for effective MM management.
• Current imaging modalities may have limitations in detecting the full extent of MM, particularly extramedullary disease.

Purpose of the Study:

• To prospectively evaluate the utility of carbon 11 ((11)C) methionine positron emission tomography/computed tomography (PET/CT) for molecular imaging of multiple myeloma (MM).
• To assess the uptake patterns of (11)C-methionine in the bone marrow and myeloma lesions.
• To compare (11)C-methionine uptake in MM patients with that in control subjects.

Main Methods:

• Nineteen patients with MM and 10 control patients underwent PET/CT after injection of (11)C-methionine.
• Bone marrow (BM) uptake and tumor manifestations were quantified using maximum standardized uptake value (SUV(max)).
• Plasma cell (35)S-methionine uptake was measured in two MM patients; SUV(max) values were compared between groups using the Mann-Whitney test.

Main Results:

• Plasma cells showed significantly higher (35)S-methionine uptake compared to normal BM cells.
• (11)C-methionine uptake was significantly higher in MM lesions (mean SUV(max) 10.2 +/- 3.5) and normal BM in MM patients (4.3 +/- 2.0) compared to controls (1.8 +/- 0.3; P < .001).
• Extramedullary MM lesions were clearly visualized (mean SUV(max) 7.2 +/- 2.4), and additional lesions were detected in normal cancellous bone in most MM patients.

Conclusions:

• Increased methionine uptake in plasma cells enables molecular imaging of active multiple myeloma using (11)C-methionine PET/CT.
• (11)C-methionine PET/CT demonstrates potential for detecting both intramedullary and extramedullary MM.
• This technique may improve the assessment of disease burden and extent in multiple myeloma.