Bone imaging is a critical aspect of care for patients with multiple myeloma (MM), and recent advances in imaging modalities have improved detection of lytic lesions and bone marrow involvement. Incorporating these new modalities into clinical practice, however, has been challenging for many clinicians, according to an article published in the 2018 American Society of Clinical Oncology (ASCO) Educational Book and a corresponding presentation at the 2018 ASCO Annual Meeting.1
“We need to educate the community about the appropriate time to order these scans and also the pros and cons of each test,” Ravi Vij, MD, MBA, of the Washington University School of Medicine in St. Louis, Missouri ― who is an author of the article ― told Cancer Therapy Advisor.
Modalities of Bone Imaging
The International Myeloma Working Group (IMWG) states that the presence of at least 1 lytic bone lesion with radiography or computed tomography (CT) or fluorine-18–2-fluoro-2-deoxy-d-glucose positron emission tomography and CT (FDG-PET/CT) or more than 1 focal lesion by MRI is indicative of MM. Bone involvement is present in about two-thirds of patients at diagnosis, and nearly all patients will develop bone disease at some point during their disease course. Bone imaging is therefore a cornerstone of MM management.
The conventional modality was whole-body skeletal survey by radiography (WBXR), but because more than 30% of trabecular bone loss must occur before this modality can detect a lytic lesion, more advanced imaging techniques were developed.
“Skeletal surveys have been the modality that we used in the work-up and follow-up of patients with MM, but the newer imaging techniques like whole-body CT scan, MRI, and PET/CT offer much more information,” Dr Vij said.
The novel modality whole-body low-dose CT (WBLDCT) is superior to WBXR for detecting lytic lesions because it has higher sensitivity, increased detection rate, and greater accuracy. WBLDCT does not require contrasting agents and uses low doses of radiation that are 2- to 3-fold lower than conventional CT.
Dr Vij noted, however, that “in the United States, it is not reimbursed by Medicare [or] most private insurance [companies], although the guidelines do recommend it.” He said that, “we feel that many doctors in the United States are not able to get [WBLDCT] for their patients, whereas Europe has done away with skeletal surveys.” WBLDCT is now the preferred imaging modality of the European Myeloma Network and the European Society for Medical Oncology for the initial assessment of MM bone disease.
FDG-PET/CT detects bone lesions with a sensitivity and specificity between 80% and 100% and is the most accurate technique for detecting extramedullary disease. It can also be used for prognostication, as the number and metabolism of focal lesions prior to stem cell transplantation has been established as an independent prognostic factor. FDG-PET/CT is also the preferred modality for monitoring metabolic response to MM treatment.
According to Dr Vij, MRI is used in the initial work-up of any plasma cell dyscrasia. “If patients have a normal set of imaging on skeletal survey, whole-body CT, and PET/CT, then an MRI may help distinguish smoldering MM from MM,” he said. Dr Vij also noted that it is used “to evaluate any episode of back pain because it is the best test to rule out spinal cord compression.”