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

Posttreatment 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 positron emission tomography (PET) with the novel CXCR4 tracer [(68)Ga]Pentixafor as a potential alternative to follow up biopsies for assessment of residual disease (noncomplete remission [CR]) after first-line Helicobacter pylori eradication. Forty-six post–H pylori eradication [(68)Ga]Pentixafor–PET/magnetic resonance imaging (MRI) examinations of 26 gastric MALT lymphoma patients, and 20 [(68)Ga]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 6 cases. Pooled examination-based accuracy, sensitivity, specificity, and positive and negative predictive values of [(68)Ga]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 = .008 and P = .006). In summary, CXCR4 imaging with [(68)Ga]Pentixafor–PET may represent a promising test for assessment of residual gastric MALT lymphomas after H pylori eradication.