Oral and Maxillofacial Radiology
Physiologic distribution of PSMA-ligand in salivary glands and seromucous glands of the head and neck on PET/CT

https://doi.org/10.1016/j.oooo.2018.01.011Get rights and content

Objectives

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) is used for detection and (re)staging of prostate cancer. However, healthy salivary, seromucous, and lacrimal glands also have high PSMA-ligand uptake. This study aimed to describe physiologic PSMA-ligand uptake distribution characteristics in the head and neck to aid in PSMA PET/CT interpretation and to identify possible new clinical applications for PSMA-ligand imaging.

Study Design

Thirty consecutive patients who underwent PSMA PET/CT for prostate cancer were evaluated. Tracer maximum standardized uptake values (SUVmax) in the salivary, seromucous, and lacrimal glands were determined visually and quantitatively. Overall and intraindividual variations were reported.

Results

All gland locations had increased tracer uptake. The mean SUVmax ± standard deviation varied: parotid 12.3 ± 3.9; submandibular 11.7 ± 3.5; sublingual 4.5 ± 1.9; soft palate 2.4 ± 0.5; pharyngeal wall 4.3 ± 1.3; nasal mucosa 3.4 ± 0.9; supraglottic larynx 2.7 ± 0.7; and lacrimal 6.2 ± 2.2. The parotid had the largest overall variation in SUVmax (5.2-22.9), and the sublingual glands had the largest mean intraindividual difference (18.1%).

Conclusions

Major and minor salivary and seromucous glands consistently have high PSMA-ligand uptake. Minor gland locations can be selectively visualized by this technique for the first time. This provides potential new applications such as quantification of present salivary gland tissues and individualization of radiotherapy for head and neck cancer or lutetium-177-PSMA radionuclide treatment.

Section snippets

Materials and Methods

The distribution of healthy salivary and seromucous gland tissues in the head and neck area was retrospectively analyzed in 30 consecutive patients who underwent total body PSMA PET/CT for staging of prostate cancer in March and April 2016. Exclusion criteria were previous salivary gland disease, aberrant tracer uptake suspected of neoplasia, and previous surgery and/or radiotherapy in the head and neck region.

PSMA PET/CT

The 30 male patients had an average age of 68 years (range 54-82 years). The mean administered activity was 173 ± 29 MBq (range 131-273 MBq). The mean time interval between tracer administration and imaging was 66 minutes (interquartile range 58-74 minutes).

PSMA-ligand uptake

All scans clearly depicted anatomic areas of salivary, seromucous, and lacrimal gland concentrations by visualizing high and homogenous uptake of PSMA-ligand (Figure 2). These areas included the major salivary glands and submucosal minor

Discussion

The results of this study provide a comprehensive qualitative and quantitative overview of tracer accumulation on PSMA PET/CT in salivary, seromucous, and lacrimal gland tissues in the head and neck. The presented distribution patterns of the major salivary glands are comparable to those (to a lesser extent) reported in studies on different topics using the same tracer.9, 10 In addition, our study illustrates the ability of PSMA PET/CT to visualize minor gland locations, for example, in the

Conclusions

PSMA PET/CT consistently depicts high tracer uptake in healthy major and minor salivary glands and lacrimal and seromucous glands. Minor salivary and seromucous glands can now be selectively visualized on imaging. Potential clinical applications of PSMA-ligand visualized by PET/CT include quantification of present salivary gland tissues and individualization of head and neck cancer treatment by radiotherapy field adaptation and 177Lu-PSMA radionuclide treatment of salivary gland cancers.

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    This research is supported by the Dutch Cancer Society (Research Grant: 10606/2016-2). The authors declare that they have no conflict of interest.

    *

    Authors contributed equally to the manuscript.

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