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(630) 938-6161
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25 N Winfield Rd Ste 505, Winfield, IL 60190-1295

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Call
(630) 938-6161
to Schedule a Consultation

25 N Winfield Rd Ste 505
Winfield IL 60190-1295

Primary Hyperparthyroidism

Imaging Studies

Central Neck Dissection

Imaging Studies

The purpose of an imaging study is to help with surgical planning AFTER the diagnosis of Primary Hyperparathyroidism (pHPT) has been established and the decision to PROCEED WITH SURGERY has already been made.

  • Given the unexpected number of parathyroid glands that are involved in pHPT (85% one gland, 10% two glands, 5% all four glands) and their variable location, it is helpful for the surgeon to anticipate how many glands to look for and where to look for them.
  • Imaging studies should not be used to make the diagnosis of pHPT or the decision to perform surgery.

Patients with negative (‘non-localizing’) imaging studies remain candidates for surgery.

  • Imaging accuracy / sensitivity varies widely from hospital to hospital, and interpretation of the images can also vary widely between radiologists.
    • Less sensitive / accurate in smaller hospitals that do not perform or interpret the imaging frequently.
    • Sensitivity is as high as 92% in high volume hospitals (imaging frequently performed and interpreted).
    • Significantly less accurate in multi-gland (double adenomas or 4 gland hyperplasia).
      • Thought to be due to the smaller size of parathyroid glands being affected.

Imaging is helpful in identifying ectopic (abnormal / unexpected location) adenomas.

  • Guides exploration via the standard neck incision approach to abnormal locations (i.e., carotid sheath, thyrothymic ligament, behind the esophagus, etc.).
  • Findings may require a separate incision (if located higher in the neck) or a different approach (e.g., through the chest cavity if located in the chest) depending on location.

Types of Imaging Study

Choice of imaging study is dependent on surgeon preference, hospital experience / strengths, and patient factors (e.g., contrast allergy, radiation exposure, costs, etc.).

Most cost effective, no radiation exposure.

Can be performed in the office during surgical consultation.

Parathyroid adenoma appears as an oval shaped, well circumscribed, hypoechoic (darker compared to the thyroid), solid mass.

  • On the posterior surface (back side) of the thyroid gland.

Parathyroid Ultrasound

Limited accuracy in patients with thicker necks, deep superior adenomas (near the spine, behind the esophagus), inferior adenomas in the mediastinum (behind the chest plate), and multi-gland disease (smaller adenomas).

At the same time, can assess the thyroid gland for thyroid nodules and their risk for cancer (rule out need for concurrent thyroid surgery).

Usually combined with one of the other imaging studies below to increase overall accuracy / sensitivity of locating a parathyroid adenoma.

Ultrasound guided FNA (Fine needle aspiration or ‘needle biopsy’) should NOT routinely be performed to confirm adenoma / location.

  • Leads to increased scarring / inflammation complicating dissection during surgery.
  • Differentiating cells in a benign thyroid nodule or cells in thyroid cancer from parathyroid cells can be difficult on needle biopsy (can lead to confusion).
  • Can cause changes in the cells that complicate final surgical pathology interpretation (ruling out cancer).
    • Should not be considered even if suspicion for parathyroid cancer is high.

Role for FNA with PTH ‘washout.’

  • Needle aspirates (sucks out) fluid from the mass, the fluid is then sent for PTH measurement, very high (> 500) PTH level will confirm parathyroid adenoma.
  • Helpful when considering difficult revision surgery or intrathyroidal adenomas (parathyroid adenoma located inside the thyroid gland – occurs rarely) to confirm the location of the adenoma prior to committing to surgery.

Technetium 99m is infused into the body via an IV.

  • This material can be seen clearly on a nuclear medicine gamma camera.

Technetium 99m is absorbed by thyroid and parathyroid tissues rapidly.

  • Initial images taken ~ 30 min after infusion.
    • Both the thyroid and parathyroid glands will be seen.
  • Second set of images taken ~ 3 hours after infusion.
    • Over time the Technetium 99m washes out of the thyroid and normal parathyroid glands, but remains in the overactive parathyroid adenoma.
    • Only the parathyroid adenoma should be visible.
  • Compare initial and delayed images, should be able to determine where the adenoma is relative to the thyroid.

Parathyroid Ultrasound

Only 2-dimensional imaging

  • Helps with side and relative height of the adenoma location, but no information on depth (superior vs inferior gland, location relative to the recurrent laryngeal nerve).

Greatly improved accuracy / sensitivity when combined with single-photon emission computed tomography (SPECT or Sestamibi SPECT).

  • Produces 3 dimensional images, helps with question of location and depth relative to other structures in the neck.

Drawbacks: invasive, time consuming, quality varies greatly from hospital to hospital, requires radiation exposure, less sensitive for multi-gland disease.

  • Less accurate when thyroiditis is present (e.g., Hashimoto’s).

4th dimension is time.

  • Iodine contrast infused through an IV.
    • When contrast is absorbed by tissues in the body, it becomes brighter on CT images.
  • Parathyroid adenomas absorb iodine rapidly (becomes bright quickly) and washes out very fast (becomes darker).
  • Three sets of images are taken: pre-contrast infusion, ~ 25 seconds after infusion (arterial phase – rapid absorption of contrast), and ~80 seconds after infusion (venous phase – enough time for rapid wash out).
    • A classic parathyroid adenoma appearance will be dark (1st image), become bright (2nd image), then dark again (3rd image).

Parathyroid Ultrasound

Good at detecting smaller adenomas, quicker then Sestamibi scans, easy protocol for all hospitals to recreate (not all hospitals / imaging centers have nuclear medicine departments for Sestamibi imaging).

Less accurate with 4 gland hyperplasia, higher radiation exposure given 3 sets of CT images taken, high contrast load (contraindicated in patients with kidney disease or severe iodine contrast allergy).

To learn more about Parathyroid:

 

Return to the Parathyroid main page here.

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