Positron Nuclide Labeled DOTA-FAPI PET Study in Colocrectal Cancer

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;