Heterogeneous PSMA ligand uptake inside parotid glands

Area of Science:

• Nuclear Medicine
• Radiology
• Oncology

Background:

• Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is a key imaging modality for prostate cancer.
• Parotid gland uptake of PSMA PET can lead to xerostomia, impacting patient quality of life.
• Understanding PSMA PET uptake patterns within salivary glands is crucial for dose management and toxicity reduction.

Purpose of the Study:

• To quantify the spatial heterogeneity of PSMA PET uptake within parotid glands.
• To identify specific regions of increased PSMA uptake in the parotid glands.
• To investigate the correlation between PSMA PET uptake and computed tomography (CT) texture features.

Main Methods:

• Analysis of [18F]DCFPyL PSMA PET/CT images from 30 prostate cancer patients.
• Application of various segmentation schemes to assess uptake patterns in parotid gland subregions.
• Calculation of Spearman's rank correlation coefficient between PSMA PET uptake and Grey Level Run Length Matrix (GLRLML, GLRLMS) CT texture features.

Main Results:

• PSMA PET uptake was significantly higher in lateral/posterior parotid regions compared to anterior/medial regions (p < 0.001).
• Maximum uptake predominantly occurred in the lateral half of the parotid glands.
• PSMA PET uptake showed significant positive correlation with CT GLRLML (p < 0.001) and negative correlation with CT GLRLMS (p < 0.001).

Conclusions:

• PSMA PET uptake exhibits significant spatial heterogeneity within parotid glands, favoring lateral/posterior locations.
• Parotid gland PSMA PET uptake is strongly correlated with specific CT texture features.
• These findings aid in understanding radiation dose distribution and mitigating salivary toxicity in prostate cancer patients.