In a patient with suspected multiple myeloma, should I order head, chest, and pelvis CT scans to rule out metastatic disease?

Imaging for Suspected Multiple Myeloma

You should order whole-body low-dose CT (not limited CT of head, chest, and pelvis) or FDG PET/CT as the preferred imaging modality for suspected multiple myeloma—this is to detect bone disease, not metastatic disease, as multiple myeloma is a primary bone marrow malignancy, not a metastatic cancer. 1

Critical Conceptual Clarification

Multiple myeloma is not a metastatic disease—it is a primary hematologic malignancy arising from clonal plasma cells in the bone marrow. 1 The imaging goal is to detect osteolytic bone lesions and extramedullary plasmacytomas, not distant metastases from a solid tumor. 1

Recommended Imaging Approach

First-Line Imaging Options

Whole-body low-dose CT is the preferred standard imaging modality for initial diagnostic workup of suspected multiple myeloma. 1 This recommendation is based on:

• Superior sensitivity: Whole-body CT detects 25.5% more bone lesions compared to conventional skeletal surveys in patients with negative plain radiographs. 1
• Better anatomic coverage: Particularly superior for detecting abnormalities in the spine, pelvis, skull, and ribs—areas difficult to visualize on plain films. 1
• Clinical impact: CT findings lead to treatment changes in up to 20% of patients compared to skeletal survey alone. 2

FDG PET/CT is an equally acceptable alternative for initial workup. 1 It offers:

• Equivalent or superior lesion detection compared to whole-body CT. 2
• Particular utility for detecting extramedullary disease outside the spine. 1
• Value in evaluating equivocal lesions and nonsecretory/oligosecretory myeloma. 2

Important Technical Considerations

• Contrast is NOT necessary for detecting myeloma bone disease and should be generally avoided in myeloma patients due to renal concerns. 1
• If PET/CT is chosen, ensure the CT component has diagnostic quality equivalent to whole-body low-dose CT, not just attenuation correction quality. 1
• The imaging must be whole-body, not limited to head, chest, and pelvis, as lesions can occur throughout the skeleton. 1

When to Add MRI

Whole-body MRI without contrast should be considered if whole-body CT or PET/CT is negative, particularly to:

• Distinguish smoldering myeloma from active multiple myeloma. 1
• Detect bone marrow infiltration with higher sensitivity (30-50% of smoldering myeloma patients have MRI abnormalities). 1, 2

Common Pitfalls to Avoid

1. Do not order limited anatomic CT scans (head, chest, pelvis only)—you will miss lesions in the spine, long bones, and other skeletal sites. 1

2. Do not confuse myeloma with metastatic cancer—the imaging strategy is fundamentally different because myeloma is a primary bone marrow disease. 1

3. Avoid conventional skeletal survey as first-line imaging unless advanced imaging is unavailable (low-resource settings)—it requires 30% trabecular bone loss to detect lytic lesions and misses lesions in 25.5% of cases. 1, 2

4. Do not use bone scintigraphy—it has no role in routine myeloma staging. 3

Evidence Quality

These recommendations are based on high-quality evidence from the 2020 NCCN Guidelines 1 and 2019 ASCO/CCO Joint Clinical Practice Guidelines 2, both representing consensus from major international expert panels. The NCCN panel specifically designates whole-body low-dose CT or FDG PET/CT as the standard of care, with moderate-to-strong strength of recommendation. 1, 2