Multiple myeloma: characterization of patients through the analysis of semiquantitative parameters with 18F-FDG PET.

Background

Multiple myeloma (MM) is the second most common hematological malignancy after non-Hodgkin lymphoma. Recently, the use of 18F-FDG PET/CT has become more and more diffused thanks to its ability to combine functional and morphological information for diagnosis, prognosis assessment, and evaluation of treatment response. This study aims to describe the semiquantitative parameters obtained from 18F-FDG PET/CT in a population of patients with MM. A comparative analysis was performed with existing literature.

Methods

This retrospective study included 50 patients with suspected MM who had undergone whole-body 18F-FDG PET/CT. The semiquantitative parameters obtained from 18F-FDG PET/CT positive scans were analyzed, specifically the number of focal lesions (FLs), the SUVmax of the “hottest” lesion, the ratio between SUVmax of the bone marrow and the spleen (marrow-to-spleen SUVmean ratio), marrow-to-spleen SULpeak ratio, and MTV.

Results

Of the total cohort of 50 patients submitted to 18F-FDG PET/CT for suspected MM, 39 subjects resulted affected by MM. The 11 negative 18F-FDG PET/CT scans of the remaining subjects were not included. 59% of patients were males, and mean age (SD) was 65 ± 7.8 years. Based on the number of FLs, the entire cohort was divided into three groups: 14 patients in group A with more than 10 lesions; 5 patients in group B had a number of lesions between 5 and 10; and 24 patients in group C presented with less than 5 lesions.

Conclusion

Semiquantitative parameters obtained through 18F-FDG PET can be useful in the assessment of staging criteria for MM, as the metabolic activity of lesions is higher in patients with extensive disease at the time of diagnosis. The predictive and prognostic relevance of these parameters as well as their role in guiding the therapeutic process toward ASCT worths further research.