FDG-PET and Multiple Myeloma

Figure 1: A radiograph of the right humerus (a part of skeletal survey) shows no abnormality in a 69-year-old man recently diagnosed with multiple myeloma.
Figure 2: FDG-PET shows multiple areas of hypermetabolism, including in the right humerus where the radiograph was negative. The majority of lesions in the ribs, scapulae and spine are not visualized on the skeletal survey.

Facts: Multiple Myeloma Staging (Durie-Salmon system)

• Based on 4 factors: Hemoglobin, serum calcium, x-ray abnormality and amount of abnormal monoclonal immunoglobulin in blood or urine
• Stage I: slightly decreased Hb, normal serum Ca, normal x-ray or only one area of bone damage, relatively small monoclonal immunoglobulin
• Stage II: between I and III
• Stage III: Hb <> 12 mg/dL, three or more areas of bone damage, large amount of monoclonal immunoglobulin

Multiple Myeloma Imaging Staging

• Staging and monitoring is very important to management decision.
• Studies of the National Oncologic PET Registry with 1300 myeloma patients showed that 36.5% of the time, treating physicians changed the intended management on the basis of PET/CT results
• Traditional radiologic staging is to use skeletal survey but it can underestimate extent and magnitude of disease. Bone scan and gallium scan are unreliable.
• Whole-body MRI has been used but it can be difficult to differentiate active disease from scar tissue, necrosis, fracture or benign disease
• Several studies performed to assess the utility of FDG PET in staging and monitoring of multiple myeloma: they found that FDG PET is useful and superior to radiography in staging of newly diagnosed non-secretory myeloma (PET can upstage disease, can show bone/bone marrow abnormality in the absence of radiographic bone damage, can show sites of extramedullary disease), restaging and monitoring of non-secretory myeloma
• FDG PET also can help differentiating multiple myeloma from monoclonal gammopathy of uncertain significance (MGUS)

FDG-PET has recently been approved for reimbursement by the U.S. Medicare & Medicaid Services.

References:

1. Durie BGM, Waxman AD, D'Agnolo A, Williams CM. Whole-body 18-F-FDG PET identifies high-risk myeloma. J Nucl Med 2002;43:1457-1463

2. Dimopoulos M, Moulopoulos LA, Terpos E. A new pet for myeloma. Blood 2009;114:2007-2008.

3. The American Cancer Society. How is multiple myeloma staged? Link