CT in endocrinology

Role

CT imaging in endocrinology is used predominantly for adrenal gland characterisation (incidentaloma work-up, phaeochromocytoma/adrenal carcinoma localisation) and, more broadly, for staging and localising endocrine tumours where cross-sectional anatomical detail is needed
A frequently used investigation once an endocrine tumour is biochemically suspected or an adrenal mass has been incidentally detected on imaging performed for another indication

Attenuation characteristics on unenhanced CT (measured in Hounsfield units) help distinguish a benign lipid-rich adenoma (low attenuation) from a more concerning lesion (higher attenuation, requiring further characterisation) - this non-contrast attenuation assessment is a key initial step in adrenal incidentaloma work-up before proceeding to contrast-enhanced imaging or biopsy

Adrenal protocol CT (unenhanced plus contrast-enhanced washout phases) provides the best non-invasive characterisation of an adrenal mass, since washout kinetics further discriminate benign adenoma from other pathology
Biochemical functional assessment must always accompany structural CT characterisation of an adrenal incidentaloma - imaging appearance alone cannot exclude a functioning tumour (e.g. subclinical Cushing syndrome, phaeochromocytoma) regardless of how benign the lesion looks structurally

Benign-appearing, non-functioning adrenal incidentaloma -> surveillance imaging per local protocol rather than immediate intervention
Indeterminate or functioning lesion -> further characterisation (MRI, biopsy where appropriate) or surgical referral depending on the specific findings and biochemical work-up result

Adrenal incidentaloma characterisation (attenuation and washout kinetics), phaeochromocytoma localisation (requiring careful pre-imaging biochemical exclusion given catecholamine crisis risk with contrast/biopsy in an unrecognised functioning tumour), biochemical assessment as a mandatory accompaniment to structural imaging

A benign-appearing adrenal mass on CT still requires biochemical functional assessment before being dismissed as clinically insignificant - imaging characteristics alone cannot exclude a subclinical functioning tumour, and skipping the biochemical work-up risks missing a hormonally active lesion requiring treatment

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