A patient with biochemically confirmed primary hyperparathyroidism needs preoperative localization before a minimally invasive parathyroidectomy. Thyroid scintigraphy shows a functioning nodule, and the surgeon also wants to know whether an adenoma lies low in the neck or behind the sternum. Which imaging plan best meets these localization requirements?

Neck-to-chest sestamibi/pertechnetate subtraction with SPECT/CT addresses both key localization issues: subtraction helps distinguish parathyroid activity from uptake in the functioning thyroid nodule, while tomographic imaging and CT provide three-dimensional localization and anatomic detail, including whether a focus is below the neck or retrosternal. Dual-phase sestamibi SPECT/CT is an established localization approach and covers the relevant region, but delayed washout alone does not subtract thyroid activity; a functioning thyroid nodule can therefore complicate interpretation. Planar subtraction images can reduce thyroid-related signal and cover the chest, but without SPECT/CT they lack fused cross-sectional anatomy, making precise localization of a deep or mediastinal focus less reliable for operative planning. Neck-only subtraction SPECT/CT provides thyroid discrimination and detailed neck anatomy, but does not image the mediastinum and could miss a retrosternal adenoma. Exam caveat: localization studies guide surgery; they do not establish primary hyperparathyroidism, which is diagnosed biochemically, and a negative study does not exclude an adenoma. Practical check: confirm that acquisition coverage extends from the neck through the mediastinum and that the subtraction and SPECT/CT datasets are technically adequate and reviewed together.