12. Patterns of Adrenal Gland Involvement from Lung Cancer Shown by 18F-Fluorodeoxyglucose Positron Emission Tomography Compared to Computed Tomography and Magnetic Resonance Imaging

Purpose: The frequency of adrenal metastases from non-small cell lung cancer (NSCLC) varies between 4 to 25%. Adrenal metastases are frequently missed (78%) by Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). The purpose of this study was to characterize the patterns of adrenal gland involvement from lung cancer by 18-F-Fluorodeoxyglucose Positron Emission Tomography (¹⁸FDG-PET).

Methods: Retrospective review of patients evaluated for known or suspected lung carcinoma. Results of ¹⁸FDG-PET, CT, MRI, and scans were compared.

Results: From February 1996 to May 2000, 91 patients with known (85 patients) or suspected (6 patients) lung cancer were evaluated with ¹⁸FDG-PET scan. Twenty-two patients (mean age 63, range 38-88 years) had abnormal adrenal glands by either ¹⁸FDG-PET (16 patients), CT (12 patients) or MRI (1 patient). In 13 cases ¹⁸FDG-PET scan was ordered to clarify CT or MRI findings. Only 7 patients showed adrenal gland involvement: 5 patients (5.5%) with unilateral disease and 2 patients (2.2%) with bilateral disease. PET depicted unsuspected findings in 9 patients: 8 patients (8.8%) with unilateral disease and 1 patient (1.1%) with bilateral disease.¹⁸FDG-PET upstaged 9 patients from limited (N1M0) to widespread disease (M1), thus obviating surgical intervention.

Conclusion: This study demonstrates the potential of ¹⁸FDG-PET scanning in revealing unsuspected adrenal metastases in patients with early stages of NSCLC as well as characterizing CT or MRI equivocal adrenal masses.