Most sensitive investigation for preoperative localization of abnormal parathyroid glands is
**Core Concept**
Preoperative localization of abnormal parathyroid glands is crucial in the management of primary hyperparathyroidism. This involves identifying the location of the parathyroid adenoma or hyperplasia to guide surgical excision. Sensitive imaging modalities are essential for accurate localization.
**Why the Correct Answer is Right**
Sestamibi scan, also known as Technetium-99m-sestamibi scan, is a highly sensitive and widely used imaging modality for preoperative localization of parathyroid glands. It works by detecting the increased mitochondrial activity in abnormal parathyroid tissue, allowing for the identification of parathyroid adenomas or hyperplasia. The scan is particularly useful in localizing parathyroid glands in the neck and mediastinum.
**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound is a useful imaging modality for parathyroid localization, but it is less sensitive than sestamibi scan, especially in cases of mediastinal parathyroid glands. It is more operator-dependent and may require expertise to interpret.
**Option B:** CT scan is not typically used for preoperative localization of parathyroid glands due to its lower sensitivity compared to sestamibi scan. However, it may be useful in identifying ectopic parathyroid glands in the mediastinum.
**Option C:** MRI is not commonly used for parathyroid localization, as it has lower sensitivity compared to sestamibi scan. However, it may be useful in cases of ectopic parathyroid glands in the mediastinum.
**Clinical Pearl / High-Yield Fact**
Sestamibi scan is a highly sensitive imaging modality for preoperative localization of parathyroid glands, but it is not 100% accurate. A combination of imaging modalities and intraoperative parathyroid hormone (PTH) monitoring may be necessary to ensure accurate localization and successful surgical excision.
**Correct Answer:** C. Sestamibi scan is the most sensitive investigation for preoperative localization of abnormal parathyroid glands.