Whole-Body Low-Dose CT Scan for Multiple Myeloma Patients
For patients with multiple myeloma, a whole-body low-dose computed tomography (WBLDCT) scan is the recommended imaging modality for bone surveillance and disease assessment. 1
Rationale for WBLDCT in Multiple Myeloma
WBLDCT has several advantages over traditional imaging methods:
- Superior to conventional skeletal survey (plain X-rays) for detecting bone lesions, with up to 80% more lesions identified 1
- Provides comprehensive evaluation of the entire skeleton in a single examination
- Can detect extraosseous findings that may impact management 2
- Delivers acceptable radiation dose (approximately 4.2 mSv) 2
- Offers high-resolution images with fast scanning time 2
Clinical Evidence Supporting WBLDCT
The 2019 American Society of Clinical Oncology (ASCO) guidelines explicitly state that "whole-body low-dose computed tomography (WBCT) scan has been shown to be superior to skeletal survey done with plain x-rays and is the preferred method for baseline and routine bone surveillance" in multiple myeloma patients 1. This recommendation is classified as evidence-based, high quality, with benefit outweighing harm.
Research has demonstrated that WBLDCT can detect bone lesions throughout the skeleton, including the skull, spine, pelvis, ribs, and long bones 2. In a study of 138 multiple myeloma patients, WBLDCT identified 328 pathologic bone findings in 81 patients, and in 40 of these patients, the bone involvement detected by CT was the only CRAB criterion present 2.
Protocol Considerations
The optimal WBLDCT protocol should include:
- Tube voltage: 120 kV
- Tube current time product: 40 mAs 2
- Coverage: From skull vertex to feet (whole-body) 1
- Reconstruction: Axial and multiplanar reformatted images 2
Alternative Imaging Modalities
While WBLDCT is the preferred method, alternative imaging modalities may be considered in specific situations:
- MRI: Useful for monitoring response of nonsecretory and oligosecretory myeloma, and if CT is inconclusive 1
- FDG-PET/CT: May be used for risk stratifying smoldering myeloma and in select situations where CT is inconclusive 1
Important Clinical Considerations
- WBLDCT should be performed at baseline for all multiple myeloma patients 1
- Response assessment should be performed with each treatment cycle initially, then at minimum every 3 months once best response is attained or on maintenance therapy 1
- For patients with apparent IgG MGUS and serum M-protein ≤15 g/L without end-organ damage, imaging may not be routinely recommended until there is evidence of progression 1
- For patients with IgA M-protein ≤10 g/L without bone pain, imaging may not be necessary 1
Pitfalls to Avoid
- Don't rely on skeletal survey alone: Plain X-rays miss up to 30% of bone lesions that require 30% trabecular bone loss to be visible 1
- Don't overlook extraosseous findings: WBLDCT can detect pleuro-pulmonary lesions and other non-bone abnormalities that may impact management 2
- Don't use excessive radiation: Low-dose protocols provide adequate diagnostic quality while minimizing radiation exposure 3
By implementing WBLDCT as the standard imaging modality for multiple myeloma patients, clinicians can achieve more accurate disease assessment, better treatment planning, and improved patient outcomes.