Prolonged effect of chemotherapy on FDG uptake of the lumbar bone marrow and its correlation with hematological parameters in patients with malignant lymphoma

Objectives To evaluate the prolonged effect of chemotherapy on FDG uptake in the lumbar bone marrow and to correlate it with hematological parameters.

Methods Fifty patients with malignant lymphoma without proven bone marrow infiltration were studied. All the patients had pre-chemotherapy PET/CT and were treated with R-CHOP regimen (n=22), rituximab (n=13), R-THP- COP (n=12) and ABVD (n=3). Short acting granulocytes colony stimulating (GCS) factor was given only for three cases, this have no affect , as the stimulatory effect of GCS factor on the bone marrow usually disappears after 10-20 days , while in our study the minimum time interval between end of treatment and post-treatment PET-CT was 27 days.The mean time interval between the end of chemotherapy and post-chemotherapy PET-CT was 86.7, the range was 27-346 days. The mean time interval between hematological examinations and pre-chemotherapy PET/ CT was 10.8 +/- 11.2 days, and mean time interval between hematological examinations and post-chemotherapy PET/ CT was 4.6 +/- 5.2 days. The bone marrow uptake of FDG was calculated by measuring the maximum standardized uptake value (SUVmax), with setting of region of interest (ROI) over the lumbar vertebrae from the first to the fifth, using three dimensional method on sagittal , coronal and tranaxial planes of FDG - PET/ CT scan . SUVmax was used rather than SUVmean to avoid calculation of the FDG uptake of intervertebral discs and the cortical bone. P value significant if less than 0.05.

Results Significant difference was observed between pre-chemotherapy SUVmax of FDG in the lumbar bone marrow (1.97 +/- 0.45) and post-chemotherapy (1.67 +/- 0.37 ) with 11.5% reduction (P < 0.00138). Gender, age and type of chemotherapy showed no significant correlation with the change in SUVmax post-chemotherapy. There was a significant difference between pre-chemotherapy WBC counts (6.42 +/- 2.03) (109/L) and post-chemotherapy (4.84 +/-2.16)(109/Liter) with 23% reduction (P < 0.00001) . There was a significant difference between pre-chemotherapy platelets counts (227 +/- 70.5)(109/L) and post-chemotherapy platelets counts (207.2 +/- 61.4) (109/L) with 8.5% reduction (P <0.005). There was no significant difference in RBC counts. The was no significant correlation between pre-chemotherapy SUVmax and pre-chemotherapy WBC, RBC or platelets counts . The was no significant correlation between post-chemotherapy SUVmax and post-chemotherapy WBC, RBC or platelets counts. There was no significant correlation between the magnitude of change in SUVmax and magnitude of chnage in WBC, RBC or platelets counts after chemotherapy.

Conclusions Post-chemotherapy FDG PET/CT efficiently detected a prolonged effect of chemotherapy on bone marrow uptake of FDG, which was associated with significant reduction in WBC and platelets counts.