A pilot study to evaluate 3′-deoxy-3′- ¹⁸F- fluorothymidine PET for initial and early response imaging in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma. Proliferation activity is considered an important prognostic marker. Immunohistochemical analysis from core biopsy or lymph node may not represent the proliferation rate. We investigated the in vivo proliferation marker 3′-deoxy-3′- ¹⁸Ffluorothymidine ( ¹⁸F-FLT) to characterize MCL. Methods: Eight untreated MCL patients were recruited prospectively. ¹⁸F-FLT PET/CT was performed 45 min after injection of ¹⁸F-FLT. ¹⁸F-FDG PET/CT served as reference. Mean ¹⁸F-FLT standardized uptake values were assessed per lesion and compared with respective ¹⁸F-FDG uptake. Correlation of mean ¹⁸F-FLT and ¹⁸F-FDG uptake in the hottest lesion to Ki67 immunostaining was performed. Five patients underwent repetitive early ¹⁸F-FLT PET. Results: All lymphoma lesions identified by ¹⁸F-FDG PET/CT showed increased ¹⁸F-FLT uptake. Semiquantitative analysis revealed a high mean ¹⁸F-FLT standardized uptake value of 9.9 (range, 5.5-15.9). Mean ¹⁸F-FLT uptake and Ki67 expressions showed a strong positive correlation. Conclusion: PET using ¹⁸F-FLT as a biomarker for proliferative activity showed a high sensitivity for MCL. ¹⁸F-FLT uptake shows a correlation with proliferation. Our results warrant further analysis of ¹⁸F-FLT PET in MCL.