Imaging Scans

Core Conclusion

Whole-body low-dose CT, MRI, and 18F-FDG PET-CT detect osteolytic bone lesions with over 90% sensitivity, replacing plain X-rays which miss marrow lesions in 30% to 50% of multiple myeloma patients.

Detailed Points

• (1) The Shift from Conventional X-Rays to WBLDCT: In the past, doctors used conventional X-rays (often called a "skeletal survey") to look for broken or damaged bones, but these are no longer recommended because they cannot detect bone damage until it has already become extensive. Today, the preferred starting point is a Whole-Body Low-Dose CT (WBLDCT) scan. This scan uses a computer to generate 3D pictures of your bones with minimal radiation exposure. It is incredibly sensitive; in fact, clinical studies show that WBLDCT can find hidden bone lesions in 25.5% of patients whose old-fashioned X-rays appeared completely normal.
• (2) When MRI is Preferred: Magnetic Resonance Imaging (MRI) uses powerful magnets and radio waves instead of radiation to take highly detailed pictures of your bone marrow and soft tissues. Your doctor will specifically prefer an MRI if there is a concern that a tumor is pressing against your spinal cord (spinal cord compression), or to evaluate soft tissue tumors (plasmacytomas). It is also the "gold standard" for spotting very early, diffuse myeloma cell growth inside the bone marrow before it even creates a hole in the bone. For example, finding more than one focal lesion that is >= 5$ mm in size on an MRI is one of the definitive markers used to officially diagnose active myeloma.
• (3) The Role of PET-CT: While a CT scan shows the physical structure of your bones, a PET-CT scan acts as an "activity tracker." It uses a safe radioactive sugar tracer (like FDG) to light up areas in your body where cancer cells are actively consuming energy and growing. This scan is the absolute best choice for finding "extramedullary disease"—meaning myeloma that has grown outside of the bone marrow and into other organs or soft tissues. Furthermore, it plays a vital role in assessing your remission depth; doctors use it to confirm "imaging MRD negativity," which proves that every single previously active tumor spot has completely disappeared or faded to normal background levels.
• (4) How Frequently Scans Should Be Repeated: You will not need a scan at every single visit, but they are scheduled strategically to protect you:

  • During Remission/Follow-up: If you have achieved a remission, guidelines generally recommend repeating an advanced whole-body scan (like a low-dose CT, PET-CT, or MRI) annually or as clinically indicated, ideally using the exact same machine and technique you used at diagnosis so the doctors can accurately compare the images.
  • For "Smoldering" Myeloma: If you have early, asymptomatic disease and your imaging findings are doubtful, doctors recommend repeating the scan in 3 to 6 months to ensure nothing is rapidly changing.
  • At Suspected Relapse: If your routine blood work shows that the myeloma protein is rising, or if you develop new bone pain, your doctor will order new imaging (such as a PET-CT or MRI) immediately. Finding new bone lesions or active tumors helps your team decide exactly when it is time to pivot to a new treatment plan.

(A quick safety note from the guidelines: When these scans are performed, they should generally be done without intravenous contrast dye to protect your kidneys, which can be fragile in myeloma patients.)

The above content is sourced from the following references

• NCCN Clinical Practice Guidelines in Oncology: Multiple Myeloma
• EHA–EMN Evidence-Based Guidelines for diagnosis, treatment and follow-up of patients with multiple myeloma
• Singapore Myeloma Study Group consensus guidelines for the management of patients with multiple myeloma
• Management of relapsed multiple myeloma: A British Society of Haematology and UK Myeloma Society guideline
• Patient Handbook
• NCCN Guidelines for Patients® Multiple Myeloma