PET imaging in ectopic Cushing syndrome: a systematic review

Area of Science:

• Endocrinology
• Nuclear Medicine
• Oncology

Background:

• Cushing syndrome from endogenous hypercortisolism presents significant health risks.
• Ectopic sources of cortisol are challenging to pinpoint using conventional CT and MRI.
• The heterogeneity of ectopic Cushing syndrome complicates imaging localization.

Purpose of the Study:

• To systematically review the literature on the effectiveness of various PET imaging radiotracers for localizing ectopic sources of Cushing syndrome.
• To compare the diagnostic performance of different PET tracers in identifying the specific etiology of ectopic Cushing syndrome.

Main Methods:

• A systematic literature review was conducted.
• Studies evaluating the use of various PET imaging radiotracers, including Gallium-based somatostatin receptor analogs and FDG, were analyzed.
• Data on tracer sensitivity and specificity for different tumor types causing ectopic Cushing syndrome were extracted.

Main Results:

• Gallium-based somatostatin receptor analogs demonstrated higher sensitivity in diagnosing bronchial carcinoids causing Cushing syndrome.
• FDG PET imaging showed superiority in detecting small-cell lung cancers and other aggressive tumors responsible for ectopic Cushing syndrome.
• Evidence for other radiotracers remains unclear due to the diverse nature of ectopic causes.

Conclusions:

• PET imaging offers potential for localizing ectopic Cushing syndrome, with specific tracers showing differential efficacy based on tumor type.
• Gallium-based somatostatin receptor analogs and FDG PET are valuable tools for specific etiologies of ectopic Cushing syndrome.
• Further large-scale studies are essential to establish definitive guidelines for the optimal PET tracer selection in ectopic Cushing syndrome.