Application Of ⁶⁸Ga-FAPI-04 PET/CT On Assessing Crohn’s Disease Intestinal Lesions

Background:Fibrosis and inflammation are major pathological changes of Crohn’s disease（CD）.Early detection and accurate severity evaluation of CD are critical for patient prognosis.Endoscopy is widely used to evaluate CD progression.Herein,we evaluated the efficacy of⁶⁸Ga-FAPI-04 PET/CT to identify lesions and assess the progression of CD.Methods:All CD patients received computed tomography enterography（CTE）,⁶⁸Ga-FAPI-04 PET/CT examination,and ileocolonoscopy within 1 week.Two independent gastroenterologists computed Crohn’s disease activity index（CDAI）of all patients.Two radiology physicians assessed the CTE images separately,and the CTE scores were calculated.Lastly,two nuclear medicine physicians independently examined the ⁶⁸Ga-FAPI-04 PET/CT images.Once the FAPI uptake of the intestinal segment was equal or higher relative to the liver（considered FAPI-positive）,the target-to-background ratio（TBR）and global FAPI PET/CT score were computed,representing the independent intestinal activity and activity of all intestinal segments,respectively.Levels of fecal calprotectin（FCP）and C-reactive protein（CRP）were determined before the endoscopy.The Crohn’s disease endoscopy index of severity（CDEIS）and the Simple Endoscopic Score for Crohn’s disease（SES-CD）were calculated during endoscopy.Finally,all data were obtained and analyzed.Results:There were 113 intestinal segments in 24 patients were assessed.⁶⁸Ga-FAPI-04 PET/CT identified out 61 of 64 endoscopically lesioned segments（endoscopic lesions detection sensitivity:95.3%）,while CTE identified 59 of them（endoscopic lesions detection sensitivity:92.2%）.According to the receiver operating characteristic（ROC）analysis,⁶⁸Ga-FAPI-04 PET/CT showed better performance in the detection of endoscopic lesions,compared with CTE（P<0.0001）.The TBR was significantly associated with the CTE score（r=0.86;95%CI,0.817-0.898;P<0.0001）and SES-CD values（r=0.86;95%CI,0.807-0.905;P<0.0001）.In addition,the global FAPI PET/CT score was significantly correlated with FCP（r=0.52;95%CI,0.02-0.81;P=0.039）、CRP（r=0.60;95%CI,0.13-0.85;P=0.014）、CDEIS（r=0.55;95%CI,0.06-0.83;P=0.028）、CDAI（r=0.81;95%CI,0.50-0.93;P<0.0001）.Conclusion:In summary,⁶⁸Ga-FAPI-04 PET/CT correlated well with endoscopic,CTE,clinical,and biomarkers of CD.It was also highly sensitive in the detection of different classes of lesions in all intestinal segments,and unlike other examinations,this technique required no patient fasting or bowel preparation.Therefore,⁶⁸Ga-FAPI-04 PET/CT may be a promising method for assessing activity of CD.