CXCR4 PET/MRI for follow-up of gastric mucosa-associated lymphoid tissue lymphoma after first-line H. pylori eradication.

Post-treatment evaluation of gastric mucosa-associated lymphoid tissue (MALT) lymphoma currently relies on esophagogastroduodenoscopy with histological assessment of biopsies. Overexpression of the G-protein-coupled C-X-C chemokine receptor type 4 (CXCR4) has been previously observed in MALT lymphoma. The aim of this prospective study was to evaluate PET with the novel CXCR4 tracer [68Ga]Pentixafor as a potential alternative to follow-up biopsies for assessment of residual disease (non-complete remission (CR)) after first-line H. pylori (HP) eradication. Forty-six post-HP eradication [68Ga]Pentixafor-PET/MRI examinations of 26 gastric MALT lymphoma patients, and 20 [68Ga]Pentixafor-PET/MRI examinations of 20 control group patients without lymphoma, were analyzed. In the MALT lymphoma group, time-matched gastric biopsies were used as reference standard, and showed CR in six cases. Pooled examination-based accuracy, sensitivity, specificity, and positive and negative predictive value of [68Ga]Pentixafor-PET for detection of residual gastric MALT lymphoma at follow-up, were 97.0%, 95.0%, 100.0%, 100.0%, and 92.9%, respectively. Maximum and mean PET standardized uptake values showed moderate correlation with immunohistochemistry-based CXCR4+ cell counts, with correlation coefficients of r=0.51 and r=0.52 (P=0.008 and P=0.006). In conclusion, CXCR4 imaging with [68Ga]Pentixafor-PET may represent a promising test for assessment of residual gastric MALT lymphomas after HP eradication.