Abstract / Summary
Purpose: Maxillofacial metastases from prostate cancer are accounts for 9–11% of metastatic jaw lesions. Optimal imaging for suspected maxillofacial metastases remains undefined. Conventional imaging often lacks sensitivity for early disease, while PET/CT may be limited due to physiologic tracer uptake in adjacent salivary glands. With increasing use of PET/CT in advanced prostate cancer, its diagnostic performance in the mandibular region requires further evaluation.
Methods: We conducted a single-institution paired retrospective study using the prospectively maintained Mayo Clinic Advanced Prostate Cancer Registry. Patients with clinically confirmed mandibular metastases who underwent molecular PET/CT ([⁶⁸Ga]Ga-PSMA-11 or [¹¹C]choline) and conventional imaging (CT or MRI) within 1 month were included. All studies were blindly reviewed by a board-certified radiologist specialized in nuclear medicine. Detection rates, anatomic distribution, and quantitative imaging parameters were assessed. paired detection rates were compared using a one-sided exact McNemar test, with a two-sided exact test performed as a sensitivity analysis.
Results: Eighteen patients with clinically confirmed mandibular metastases underwent 36 paired imaging evaluations (18 molecular PET/CT and 18 conventional studies). Median age was 70.5 years (IQR, 60–77), and median Gleason score was 8 (IQR, 7–9). At detection of mandibular metastasis, 56% of our cohort had hormone-sensitive and 44% had castration-resistant disease. Molecular PET/CT detected mandibular involvement in 18/18 patients (100%; 95% CI, 81–100%) versus 13/18 (72.2%; 95% CI, 47–90%) with conventional imaging. All five discordant cases were detected by molecular PET/CT but not conventional imaging, with no discordant cases favoring conventional imaging (one-sided exact McNemar p = 0.031; two-sided p = 0.063). Mandibular involvement was predominantly unilateral (94.4%), most commonly involving the body (50%), followed by the ramus (28%) and condyle (17%). Median SUVmax was 6.3 (IQR, 4.4–16.9) for PSMA PET/CT and 4.3 (IQR, 3.8–8.5) for choline PET/CT; median lesion volume was 5.0 mL (IQR, 1.1–11.3).
Conclusions: Molecular PET/CT identified all clinically confirmed mandibular prostate cancer metastases in this paired cohort, including five cases not detected by conventional imaging. Despite physiologic tracer uptake in adjacent salivary structures, mandibular metastatic disease remained detectable on molecular imaging. These findings suggest that molecular PET/CT may provide complementary value when mandibular metastasis is suspected, particularly when conventional imaging is negative or equivocal.