This clinical trial studies positron emission tomography (PET) imaging utilizing 18F-(2S,4R)4-fluoroglutamine, a glutamic acid derivative, to image patients with malignant tumor. [18F]Fluoroglutamine PET may provide additional information that help diagnose and stage cancer patients.

Inclusion Criteria:

• Age between 18-79;
• The patient must be able to give informed consent;
• Patients can finish PET/CT scan without tranquilizers;
• Patients with pathology-proven cancer or a tumor highly suspected to be malignant ;
• Lesions can be measured and assessed at the RECIST 1.1 standard;
• No chemotherapy, radiotherapy or immune/biologic therapy,or biopsy were allowed between the 18F-FDG and the 4-[18F]Fluoroglutamine PET/CT.

Exclusion Criteria:

• Pregnant or lactating patients;
• Inability or refusal to have at least one peripheral intravenous line for intravenous access;
• From assays obtained <2 weeks prior to study enrollment（ULN：the upper limit of normal value ）:Bilirubin>1.5*ULN,AST/ALT >2.5 * ULN, Albumin< 3 g/dl, GGT > 2.5 x ULN if ALP> 2.5 x ULN, Creatinine>1.5*ULN or creatinine clearance <60ml/min；
• Patients with a history of allergic reaction to this drugs or its analogues；
• patients with poor compliance;
• Acute major illness