Negative Parathyroid Scintigraphy: What Can You Conclude?

Endocrine · 2 min read

Understanding the limits of localisation.

A patient with biochemically established primary hyperparathyroidism has a negative technetium-99m sestamibi scan. Does this exclude an abnormal parathyroid gland? No. Scintigraphy is a localisation test for surgical planning; the diagnosis rests on biochemical assessment. [1,3]

What a negative result means

An adequate negative study means that no convincing hyperfunctioning parathyroid focus was localised with the technique used. It does not establish that all glands are normal, exclude an adenoma or multigland disease, or determine whether surgery is indicated. Patients who meet surgical criteria remain candidates despite nonlocalising imaging. [1,3]

Why an abnormal gland may not be seen

These mechanisms explain nonvisualisation; none can be diagnosed from a negative scan alone. [1,2]

Three checks before concluding

1. Revisit the early images. Review early and delayed images together when using a dual-phase protocol. Absence of delayed retention alone is insufficient because some lesions wash out rapidly. [2]

2. Check localisation and technical adequacy. Review available SPECT/CT, including ectopic sites within the imaged field. Document motion, inadequate coverage, or poor image quality rather than calling a compromised examination simply negative. [2]

3. Correlate with the clinical question. Review ultrasound and previous localisation studies. In a surgical candidate, negative or discordant imaging should prompt specialist assessment, not reversal of a biochemical diagnosis. [3]

Reporting examples

Adequate negative examination: “No definite scintigraphic localisation of hyperfunctioning parathyroid tissue. A negative study does not exclude primary hyperparathyroidism.”

Technically limited examination: “Localisation is limited by significant patient motion. No definite focus is identified, but the examination is not reliably negative.”

What may follow

If further localisation will influence surgery, specialist-directed options include expert neck ultrasound, fluorine-18 fluorocholine PET/CT, or 4D-CT, selected according to prior studies, availability, and patient factors. [1] Nonlocalising imaging does not automatically prevent surgery; an experienced parathyroid surgeon can assess the appropriate operative approach, including bilateral exploration. [3]