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CASE 1:
The case of the hiding parathyroid adenoma

(Courtesy: Department of Nuclear Medicine, Tygerberg Hospital and University of Stellenbosch)

Clinical information:

  • 56 year old female
  • On Eltroxin for hypothyroidism
  • Elevated PTH (32), serum Ca (3,3) with normal renal function
  • TSH elevated (10)
  • Parathyroid scintigraphy for detecting adenoma or hyperplasia as cause for clinical and biochemical primary hyperparathyroidism

Scintigraphy:

  • Tc-99m pertechnetate/ Tc-99m MIBI subtraction scintigraphy performed:
Pertechnetate
Pertechnetate
30 min MIBI
30 min MIBI
Subtraction image
Subtraction image
30 min MIBI
30 min MIBI
Delayed MIBI
Delayed MIBI

Scan findings:

Remarkably good uptake of pertechnetate in thyroid of patient on thyroid replacement therapy: compatible with underlying Hashimoto thyroiditis. Moderately enlarged thyroid with slightly less uptake in left lobe.

In contrast, the Tc-99m-MIBI image shows filling-in of the left lobe. A clear difference in activity between the pertechnetate and MIBI images is seen in the region of the left upper thyroid lobe on the subtraction image.

On the delayed MIBI images no differential retention of the tracer is seen in this area.

Conclusion:

The findings are compatible with the presence of a parathyroid adenoma in the region of the upper pole of the left thyroid lobe.

Outcome:

A parathyroid adenoma was found in the region of the left upper pole of the thyroid during surgery and removed. Parthyroid hormone levels subsequently returned to normal.

Comments:

It has been suggested in recent years that early and delayed Tc-99m MIBI parathyroid scintigraphy could replace the subtraction technique (performed with either Tl-201/Tc-99m pertechnatate, Tc-99m MIBI/Tc-99m pertechnetate or Tc-99m MIBI/I-123). In our department we still prefer the subtraction technique for the following reasons:

  1. It allows evaluation of thyroid function and morphology
  2. Differential washout from abnormal parathyroid tissue is frequently not seen.
    3.
This case is a good example of a "hiding" parathyroid adenoma that would have been very difficult to diagnose on early/delayed Tc-99m MIBI scintigraphy alone.

- Prof Ben van Heerden

 

For more information, visit the following interesting links:

SNM procedure guideline for parathyroid scintigraphy. (Please note, this file is in *.pdf format and requires Adobe Acrobat Reader to view.
If you don't have this reader, click here to obtain it free of charge.

Your parathyroid

Pre-operative localisation of endocrine tumours (this site even contains a 3-D SPECT image!)
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