Intrapatient variability of 18F-FDG uptake in normal tissues

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Medical Imaging

Background:

• Standardized uptake value maximum (SUVmax) variability in normal tissues affects 18F-FDG PET/CT interpretation.
• Identifying stable reference tissues is crucial for accurate quantitative analysis.

Purpose of the Study:

• To assess the impact of serum glucose and other factors on SUVmax variability in normal tissues across repeated 18F-FDG PET/CT scans.
• To identify optimal reference tissues for quantitative imaging.

Main Methods:

• Retrospective analysis of 334 18F-FDG PET/CT scans from 167 patients, including 38 diabetics, with two scans per patient.
• SUVmax was calculated for ten normal tissues (brain, tonsil, blood pool, heart, lung, liver, spleen, bone marrow, fat, iliopsoas muscle).
• Correlations with serum glucose, BMI, injected dose, and uptake time were analyzed.

Main Results:

• Lung and heart SUVmax showed significant differences between scans (P=0.003, P=0.024).
• Brain SUVmax negatively correlated with glucose in diabetics (r=-0.537, P=0.001). Liver SUVmax correlated positively with BMI (r=0.416-0.453, P<0.001).
• Liver SUVmax was influenced by injected dose and uptake duration; spleen and muscle SUVmax were consistently affected only by injected dose.

Conclusions:

• Liver, muscle, and spleen exhibit satisfactory test-retest stability for use as reference tissues.
• Spleen and muscle are more optimal reference tissues due to their sole association with the injected 18F-FDG dose, minimizing confounding factors.