FDG PET/CT upstages radiography in unmasking multiple myeloma

Although the outlook for patients with multiple myeloma, a cancer that attacks blood plasma and bone marrow, is typically dismal, F-18 FDG PET/CT has emerged as a strategy that could provide earlier diagnosis as well as more accurate treatment monitoring and patient prognosis, according to a review in the April issue of the American Journal of Roentgenology.

An estimated 20,000 new diagnoses of multiple myeloma are made in the U.S. annually. About half that number of people are expected to die of the disease every year. Multiple myeloma is ranked the number one cause of primary bone cancers and second in incidence of blood malignancy. The workhorse of myeloma imaging has been radiography for some time, but F-18 FDG PET/CT may offer a potential alternative to radiography, according to Ankit Agarwal, MD, from the department of radiology at Boston University School of Medicine, and colleagues.

In this retrospective, multiple-study review citing more than 50 peer-reviewed sources, researchers sought to glean specific value and drawbacks of F-18 FDG PET/CT as an imaging technique for multiple myeloma case management. Across three studies, F-18 FDG PET/CT found more cancerous lesions than radiography and provided better staging of multiple myeloma.

In one prospective study of 46 new diagnoses, FDG PET was more effective for lesion detection in 46 percent of patients, whereas whole-body radiography was better at finding lesions in eight of the subjects. In another study, F-18 FDG PET/CT provided a more thorough assessment of lesions than whole-body radiography by finding additional lesions in 16 of 28 participants. In six out of the seven studies presented in a concordance review, FDG PET showed superior disease staging and detection of lesions than whole-body radiography.

“Overall, FDG PET/CT is a superior imaging modality in the diagnosis and staging of multiple myeloma compared with conventional imaging, and it influences the intended management for a significant number of patients,” wrote the authors.

Potential issues with 18-F FDG PET/CT were contraindications with corticosteroid treatment concurrent with imaging, due to suspected increases of false-positive results. There were reports of both false-negative and false-positive results using the technique cited in one study and another showed limitations to skull imaging of lytic lesions.  However, this observation may have been due to the field of view of the imaging studies from the base of the skull to midthigh, according to the researchers. Utilizing PET on its own was found to miss lytic skeletal lesions smaller than 10 millimeters in size and diffuse spinal lesions in one study. Any lack of specificity was noted to be improved by the structural component of CT.

Although evidence is mounting for the use of F-18 FDG PET/CT for multiple myeloma patients, adoption of the technique remains slow. However, the authors suggested a change in consensus as this review and further research are incorporated into future imaging guidelines.