PET and PET/CT imaging remains promising, and with current and further improvements, PET and PET/CT imaging may make the diagnosis and evaluation of gastric cancer more standardized and accurate.

This retrospective and prospective study was conducted to evaluate the effectiveness of 18 F-FDG PET/CT imaging in diagnosis of gastric cancer in correlation to other imaging modalities and clinical follow up.

This study included 50 patient pathologically proved gastric cancer. After obtaining written consent from the participants, detailed history was obtained from participants with the help of their data sheets, revision of pathology report (confirmed diagnosis of primary GC), the referral report from the treating physician and any imaging modalities patients were done, FDG PET/CT study was done using dedicated PET/CT scanner, and PET analysis was performed qualitatively and semi qualitatively, tissue biopsy was obtained from patients whenever it was possible.

Results of the current study demonstrate that FDG PET/CT was more accurate and more sensitive than CT in detection of occult distant metastases in advanced or equivocal cases, detection of metabolically active LNs that are morphologically normal on CT, helpful for recurrence detection, and informative for early metabolic response in FDG-avid tumors using standardized criteria (PERCIST),that may not be apparent using other modalities, and may have prognostic value that can change patient management.

PET/CT was more accurate than CT in Detection of Distant metastasis of gastric cancer (liver metastasis, lung metastasis, bone metastasis).

¹⁸F-FDG PET/CT is not a stand-alone staging tool for gastric cancer, but used selectively it meaningfully improves detection of distant metastasis, refines patient selection for radical treatment, and reduces futile surgery.

Clinicians must interpret PET/CT results in light of histologic subtype and complementary diagnostic procedures (endoscopy, laparoscopy, CT). Future work should validate FAPI tracers and define precise clinical pathways where PET/CT adds cost-effective benefit.

Inclusion Criteria:

1. Patients diagnosed as Gastric Cancer on surgically resected specimens.
2. Patients with gastric and extragastric metastasis.
3. Patients with gastric cancer either operated or not

Exclusion Criteria:

1. Patients with second malignancy (Double primary).
2. Patient without proven pathology of Cancer Stomach.
3. Severely ill patient (patient with disturbed conscious level, or couldn't lay supine during the imaging).
4. Uncontrolled diabetic patient with blood glucose level more than 200mg\dl.
5. Pregnant women.

The Current Retrospective and Prospective study was conducted among 50 histologically confirmed Gastric Cancer patients ,mean age of the studied cases was 57.58 ± 10.26 years and ranged between (35-77) years. Moreover, the study included 29 males (58%) and 21 females (42%).

the individual participant data will not be made available to other researchers to maintain patient confidentiality.