To evaluate the normal physiological distribution of positron nuclide labeled DOTA-FAPI PET/CT in human body and its diagnostic efficiency for colorectal cancers

Participants first undergo an 18F-FDG PET/CT, followed by 68Ga-FAPI04 PET/CT in groups. The purpose of the study is to explore the possibility of superiority of FAPI in diagnosis of colorectal cancer (TNM staging) by the comparison of the two tracers uptake (the maximum of standardized uptake value, SUVmax). Histopathology and conventional imaging follow-up are served as the reference standard.

Inclusion Criteria:

• ECOG score 0-2
• patients with newly diagnosed or previously treated colorectal cancers
• patients who underwent paired 18F-FDG and 68Ga-FAPI PET/CT for tumor staging to decide the most proper treatment strategy
• patients who underwent paired 18F-FDG and 68Ga-FAPI PET/CT to detect tumor recurrence and metastases (repeat staging)
• expected survival ≥12 weeks
• blood routine, liver and kidney function meet the following criteria : blood routine: WBC≥4.0×109L or neutrophils ≥1.5×109L, PLT≥100×109/L, Hb≥90g/L;PT and APTT ULN 1.5 or less; Liver and kidney function: t-bil ≤1.5×ULT(upper limit of normal value), ALT/AST≤2.5ULN or ≤5×ULT(subjects with liver metastasis), ALP≤2.5ULN(ALP≤ 4.5ULN if there is bone metastasis or liver metastasis);BUN 1.5 x or less ULT, SCr 1.5 x or less ULT
• at least one measurable target lesion according to RECIST1.1
• women must use effective contraception during the study period and for 6 months after the end of the study (effective contraception means sterilization, hormone devices, condoms, contraceptives/pills, abstinence or vasectomy by a partner, etc.);Men should consent to subjects who must use contraception during the study period and for 6 months after the end of the study period
• able to understand and sign the informed consent voluntarily, with good compliance.

Exclusion Criteria:

• severe abnormalities of liver and kidney function;
• women preparing for pregnancy, pregnancy and lactation;
• cannot lie supine for half an hour;
• refuse to join the clinical researcher;
• suffering from claustrophobia or other mental illness;