MRI and 18F-fluorothymidine PET-MR for the early evaluation of renal and bone marrow effects in 177Lu-DOTATATE therapy.

BACKGROUND

This study aimed to evaluate whether early renal and bone marrow effects - previously identified through laboratory tests - can be detected using MRI and 18F-FLT PET-MR in neuroendocrine tumor patients treated with 177Lu-DOTATATE. Despite known early changes, precise clinical tools to monitor these effects remain limited.

METHODS

Ten patients with metastatic NETs, scheduled to initiate at least four treatment cycles of 177Lu-DOTATATE, were included. MRI was performed at all designated treatment time points, whereas F-FLT PET was acquired only at baseline and on day 2 following treatment initiation. Bone marrow (BM) fat conversion, proliferative activity, and renal effects were studied with MRI and 18F-FLT PET-MR. Laboratory tests for hematology and kidney and liver function were taken.

RESULTS

Six patients completed the full imaging protocol with MRI, of whom 18F-FLT PET-MR examinations were performed in two patients. All subjects demonstrated increased BM fat content during the study interval, with a mean of +12.8%. The magnitude of the increase varied substantially, from +3.8% to +23.5%. There was a strong correlation between increased BM fat content and reduced peripheral blood cell counts. Decreased FLT uptake was found on day 2 after treatment. An increase in renal arterial flow and parenchymal volume was detected during the first week after treatment. No sustained renal effects were observed.

CONCLUSIONS

The hematological effects observed with laboratory tests after 177Lu-DOTATATE treatment in neuroendocrine tumor patients can be detected by MRI as an increase in bone marrow fat content. This finding was supported by decreased FLT uptake on 18F-FLT PET-MR, indicating decreased bone marrow cell proliferation. MRI can also identify renal effects associated with this therapy.