Intestinal stricture is a complication of Crohn's disease (CD), which is thought to be the result of chronic transmural inflammation combined with a dysregulated wound-healing process. While inflammatory strictures may respond to anti-inflammatory treatment, fibrotic strictures are usually anti-inflammation resistant, requiring further endoscopic balloon dilation or surgical intervention. Therefore, to determinate the inflammatory or fibrotic nature of intestinal stricture is a key step in the treatment of CD. 18F-FDG is a radiotracer reflecting the glucose metabolism of disease and is usually accumulated in inflammatory disease. 68Ga-FAPI is a novel radiotracer that specifically targets fibroblast activation protein (FAP). FAP is a membrane glycoprotein expressed on activated fibroblasts, which are key cells in the process of fibrotic intestinal stricture of CD. In this study, we hypothesis that the inflammatory or fibrotic nature of intestinal stricture can be non-invasively evaluated by 18F-FDG and 68Ga-FAPI PET/CT in patients with CD.
Patients with intestinal stricture will undergo 18F-FDG and 68Ga-FAPI PET/CT on two consectutive days. The accumulation of 18F-FDG and 68Ga-FAPI at the site of stricture will be determined by standard uptake value (SUV), molecular volume (MV), and total molecular index (TMI). In patients with a planned surgical resection of one or more stricture (s), the image results will be compared with histological findings.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
30
Participants will undergo 18F-FDG (0.12-0.15mCi/kg) and 68Ga-FAPI (3-6mCi) PET/CT on two consecutive days. At least 6 hours of fast is required for 18F-FDG PET scan, while no dietary control is necessary for 68Ga-FAPI PET scan. If the patients are on metformin, discontinuation of 48 hours is required before 18F-FDG injection to minimize the bowel uptake. If the patient is planned for surgical resection of one or more stricture (s), the scans have to be completed within a maximum period of 30 days before the surgery.
SUVmax of stenotic intestine
The SUVmax of stenotic intestine will be determined on 18F-FDG and 68Ga-FAPI PET scan to reflect the highest extent of inflammation and fibrosis, respectively.
Time frame: Day 30 after PET scan
MV of stenotic intestine
The MV of stenotic intestine will be determined on 18F-FDG and 68Ga-FAPI PET scan to reflect the involved area of inflammation and fibrosis, respectively.
Time frame: Day 30 after PET scan
TMI of stenotic intestine
The TMI of stenotic intestine will be determined on 18F-FDG and 68Ga-FAPI PET scan to reflect the overall extent of inflammation and fibrosis, respectively.
Time frame: Day 30 after PET scan
Histological findings
In patients with surgical resection of stenotic intestine, the extent of inflammation and fibrosis will be determined.
Time frame: Day 90 after surgery
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