What is the best way to assess for new bone lesions in treated multiple myeloma?

Assessment of New Bone Lesions in Treated Multiple Myeloma

Whole-body low-dose computed tomography (WBLD-CT) is the preferred imaging modality for detecting and monitoring new bone lesions in treated multiple myeloma patients due to its superior sensitivity compared to conventional radiography. 1

Primary Imaging Modalities for Bone Lesion Assessment

Whole-Body Low-Dose CT (WBLD-CT)

• WBLD-CT is the standard procedure for detecting lytic bone disease in multiple myeloma patients with high-quality evidence supporting its use 1
• WBLD-CT can detect up to 60% more relevant findings compared to conventional skeletal surveys, leading to treatment changes in up to 20% of patients 1
• WBLD-CT is quick to perform (examination completed in 2 minutes or less) and provides more accurate evaluation of areas with instability or fracture risk 1
• In prospective studies, WBLD-CT consistently identified more bone lesions per patient (8.2) compared to conventional skeletal surveys (3.6) 2

Alternative Imaging Modalities

PET/CT

• FDG-PET/CT is particularly valuable for:
  • Evaluating extramedullary disease 1
  • Assessing treatment response in nonsecretory and oligosecretory myeloma 1
  • Defining complete or stringent complete response 1
  • Detecting disease progression 1, 3
• If using PET/CT instead of WBLD-CT, ensure the CT component has imaging quality equivalent to WBLD-CT, not just for attenuation correction 1

MRI

• Whole-body MRI is superior for detecting bone marrow involvement prior to development of osteolytic destruction 4
• MRI is the gold standard for evaluation of spinal and vertebral lesions 4, 3
• MRI can be useful in patients with smoldering multiple myeloma, as 30-50% of such patients will have bone marrow abnormalities 1
• Caution: MRI may show nonspecific lesions and occasionally overestimate the extent of bone disease 1

Imaging Algorithm for Treated Multiple Myeloma

1. Baseline Assessment:

   • WBLD-CT as the primary imaging modality 1
   • Consider additional focused X-rays for skull and rib lesions, which may not be well detected by WBLD-CT 1

2. Routine Surveillance:

   • WBLD-CT for regular bone disease monitoring 1, 2
   • Minimum assessment frequency of every 3 months during active treatment 1
   • May be assessed less frequently once best response is attained or on maintenance therapy, but at minimum every 3 months 1

3. Special Situations:

   • For nonsecretory or oligosecretory myeloma: Consider PET/CT for monitoring response 1, 3
   • If WBLD-CT is inconclusive: Use PET/CT or MRI for further evaluation 1
   • For suspected spinal cord compression: MRI is the preferred imaging method 1

Clinical Pitfalls and Considerations

• Conventional skeletal surveys significantly underestimate progression rates compared to WBLD-CT 2
• Healing of lytic lesions is slow, taking 3-6 months to begin appearing and more than a year to mature 5
• Skull and rib lesions are not well detected by WBLD-CT or MRI compared to conventional skeletal surveys; focused X-rays may still be valuable if these areas are of concern 1
• MRI and radiographs cannot always differentiate between treated bone marrow lesions and viable neoplastic tumors; PET/CT may help in these cases 1, 3
• For patients with established diagnosis, avoid unnecessary bone marrow biopsies and redundant imaging 6

Comprehensive Assessment Approach

• Combine imaging assessment with regular monitoring of serum and/or urine M-protein values and serum free light chain levels 1
• Assess response with each treatment cycle during active therapy to determine treatment effectiveness 1
• Consider the pattern of bone disease when selecting imaging modality - diffuse disease may be better evaluated with different techniques than focal lesions 1, 3