Is low-dose computed tomography (CT) suitable for patients with multiple myeloma?

Whole Body Low-Dose CT for Multiple Myeloma

Whole body low-dose CT (WBLDCT) is strongly recommended as the primary imaging modality for patients with multiple myeloma, as it significantly outperforms conventional skeletal surveys in detecting bone lesions. 1, 2

Advantages of WBLDCT in Multiple Myeloma

• WBLDCT detects 25.5% more osteolytic lesions compared to conventional skeletal surveys, leading to treatment changes in up to 20% of patients 2, 1, 3
• WBLDCT is particularly superior for detecting abnormalities in the spine and pelvis, as well as the skull and ribs, which are difficult to visualize with skeletal surveys 2, 1
• WBLDCT is faster to perform and more convenient for patients, with radiation doses of 3.2-4.8 mSv, significantly lower than standard CT protocols 1, 4
• WBLDCT extends from skull vertex to knees without requiring intravenous contrast, which should generally be avoided in myeloma patients 1, 2

WBLDCT Technical Specifications

• Recommended detector configuration: 80×0.5 mm, with scanning range in a single spiral acquisition from skull to proximal femoral bones 4
• Standard parameters: tube voltage 120 kVp, current tube time product 86 mAs, slice thickness 1 mm 4
• Two sets of axial images should be reconstructed - one for bone assessment and one for soft tissue evaluation 4
• Secondary coronal and sagittal reconstructions should be generated for comprehensive evaluation 4

Comparison with Other Imaging Modalities

• FDG-PET/CT is an acceptable alternative to WBLDCT, offering additional value in detecting extramedullary disease and metabolically active lesions 2, 3
• If using PET/CT instead of WBLDCT, the CT component must have imaging quality equivalent to WBLDCT, not just for attenuation correction 2, 1
• MRI is particularly useful when WBLDCT or FDG PET/CT is negative, especially to differentiate between smoldering myeloma and active multiple myeloma 2, 1
• The LDCT co-registered to PET has shown comparable performance to standalone WBLDCT (sensitivity 89.4%, specificity 98.3%, accuracy 93.5%), suggesting potential for using PET/CT as a single multimodal imaging method 5

Imaging Protocol Recommendations

• For initial diagnostic workup, either WBLDCT or FDG PET/CT is recommended by the NCCN Panel 2, 1
• Conventional skeletal survey should only be used when advanced imaging is not available (e.g., in low-resource settings) 2, 1
• For follow-up after treatment, the same imaging modality used during initial workup should be used for consistency 1, 3
• Assessment should be performed at minimum every 3 months during active treatment 1, 3

Clinical Considerations

• A middle-frequency reconstruction algorithm (B50f kernel) has proven beneficial for all energy protocols 6
• Image quality may be reduced in patients with diffuse skeletal infiltration or concurrent osteoporosis 6
• WBLDCT is obligatory at diagnosis but not required during response assessment unless symptoms develop, according to the EHA-ESMO clinical practice guidelines 2
• PET-CT is optional at diagnosis but obligatory to confirm imaging MRD (minimal residual disease) negativity 2

WBLDCT represents a significant advancement in multiple myeloma imaging, providing superior detection of bone lesions with reasonable radiation exposure and should be the standard imaging approach for these patients.