Characterization of Abdomino-pelvic Lesions by 18Fluorine- Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

positron Emission Tomography combined Computed Tomography is a hybrid imaging that provides both anatomical and functional data that helps to differentiate between benign and malignant diseases. [18F]FDG is taken up by both normal cells utilizing glucose like (kidneys, ureters and urinary bladder due to urinary excretion, Variable degrees of uptake can also seen in the liver, spleen, bone marrow, bowel, testes and uterus) .and also the tumor cells which usually have a high glucose demand. This uptake is mediated by the cell surface carrier molecules designated as glucose transporters (GLUT) and can be measured with the semi quantitative index called standardized uptake values (SUV) Cancer cells divide rapidly and have greater metabolic rates. Through the upregulation of glucose transport proteins on the cell membrane, cancer cells exhibit enhanced glucose uptake . Studies have demonstrated that SUV of 2.5 can differentiate malignant versus benign tissues , thus, Proper characterization of abdomino-pelvic lesions will lead to improve chances for successful management and treatment.

Multiple studies have shown that Dual-time point (DTP) 18F-FDG PET/CT may provide more help in the differentiation of malignant lesions from benign ones.as Dual-Time-Point PET/CT involves two scans, one early and one delayed, allowing for the assessment of FDG uptake kinetics, malignant tumors tend to show increased FDG uptake over time, indicating higher glucose metabolism. But benign Lesions or those with inflammatory processes may show a decrease or no significant change in FDG uptake over time.

FDG activity in urine interferes with tumor activity. Therefore, the value of FDG PET has only a limited role in detecting tumors in the bladder wall and urinary tract, Thus several methods have been investigated and tested to reduce urine FDG activity: catheterization, dual-phase imaging, early PET images, late PET images after voiding, oral hydration, and forced diuresis

Inclusion criteria

• Inclusion criteria: All of the patients were suspected of having malignancy (new, recurrent or metastatic) based on pathology or conventional radiological studies and were referred to nuclear medicine unit for 18F-FDG-PET-CT scan

Exclusion criteria

• patients underwent recent abdominal or pelvic surgery.
• patients with blood glucose level ˃200 mg/dL
• Pregnancy