Pre-Treatment FDG PET Bone Marrow (BM) Uptake and Disease Involvement. Can Semiquantitative Measures Discriminate Between A Normal, Hypercellular or Infiltrated Bone Marrow?

PET studies are used on a regular basis to stage lymphoma patients pretreatment. Bone marrow uptake (BMu) can be associated with disease involvement, however occasionally uptake is related to benign etiologies (anemia, stimulation, a hypercellular marrow etc…). Uncovering quantitative and qualitative parameters to elucidate the etiology of (BMu) may help the radiologist and oncologist in cases where a BM biopsy (BMb) cannot be performed or interpreted by the pathologist or is unavailable. We looked retrospectively at a group of consecutive lymphoma patients (pts) who had an initial staging PET scan. Out of 121 patients, 36 had a (BMb) report available for review. We attempted to evaluate whether semi quantitative parameters – maximum standardized uptake value (SUVm); Average SUV (SUVav); SUVm/Mediastinal blood pool (MBP) ratio - could discriminate between different bone marrow patterns (normal, hypercellular, positive). We also looked at the type of BMu (none; mild; prominent) and pattern (patchy; diffuse; focal). The average age of our patient population was 52.19. 66.66% were males (24/36). Most of our patient’s had a normal BMb. 25 % (9/36) had a positive BM. In the BM positive group, no pts had patchy uptake and 2 pts were found to have no appreciable uptake. In the BM normal group 71.5 % (15/21) had either mild or prominent uptake and only 28.5% had no uptake. None had focal uptake and 90% of pts had diffuse uptake. The majority of whole cohort had a SUVm> 2.5: 90 % of BM normal; 100% of hypercellular BM and 88.88% of the BM positive group and an SUVm/MBP>2.5: 52.4%; 66.66% and 55.5% respectively. Using a Chi-square test BM Pathology level was overall significantly different across the BMu patterns (p=0.0192). Analysis looking at BM positive versus BM negative groups, shows BM pattern is no longer a significant variable to predict BM pathology (p=0.168). Subsequently, the odds ratio of having only positive BM pathology based on focal vs. patchy pattern is not significant. Conclusion: No qualitative or semi quantitative parameters were found to be statistically significantly associated with BM pathology. Further exploration in a larger cohort is necessary.