CG11SZZ
Planar Nuclear Medicine Imaging Parathyroid Glands to None with None, Thallium 201 (Tl-201) Approach
Procedural Specifications
| Clinical Axis | Detail Definition |
|---|---|
| Section | C Nuclear Medicine |
| Body System | G Endocrine System |
| Operation | 1 Planar Nuclear Medicine Imaging |
| Body Part | 1 Parathyroid Glands |
| Approach | S Thallium 201 (Tl-201) |
| Device | Z None |
| Qualifier | Z None |
Operation Definition
Introduction of radioactive materials into the body for single plane display of images developed from the capture of radioactive emissions
Procedure Overview
This family describes single-plane radioactive imaging of endocrine glands, most often a thyroid scan and sometimes a parathyroid or adrenal scan. A small amount of radioactive iodine or technetium pertechnetate is swallowed or injected, the gland absorbs it in proportion to how active its cells are, and a gamma camera held in one or two fixed positions captures flat, two-dimensional pictures of the uptake pattern.
Physicians use this scan to tell apart different causes of an overactive thyroid, such as Graves' disease versus a single toxic nodule, to characterize a thyroid nodule found on ultrasound, or to look for residual or recurrent thyroid cancer tissue after surgery. A parathyroid version, usually done with a sestamibi tracer, helps locate an overactive parathyroid gland before surgery. The scan is painless and usually completed within an hour of the tracer being given, though thyroid studies sometimes require the patient to return for delayed images.
Anatomy & Axis Detail
Parathyroid Glands
The parathyroid glands are typically four tiny structures embedded behind or near the thyroid that regulate calcium homeostasis by secreting parathyroid hormone, and their small size combined with variable location, including occasional ectopic sites in the mediastinum, makes them a particular challenge for planar nuclear imaging. Radiotracers such as technetium-99m sestamibi are taken up preferentially by hyperfunctioning parathyroid tissue, including adenomas, and imaging typically relies on comparing early and delayed images or subtracting thyroid uptake to isolate the smaller parathyroid signal from the much larger, more avid thyroid gland immediately adjacent to it. This study is most often requested before parathyroidectomy to localize an adenoma or hyperplastic gland preoperatively, sparing the surgeon a broader neck exploration.
Radionuclide: Thallium 201 (Tl-201)
Thallium 201 (Tl-201) identifies studies using this radionuclide, historically significant for myocardial perfusion imaging because it is taken up by viable heart muscle in proportion to blood flow. It has largely been supplemented by technetium-based agents for cardiac imaging but remains coded distinctly when used, differing from Tc-99m tracers and from positron-emitting isotopes used in PET perfusion studies.
Coding & Documentation
Coding from this family depends on documentation showing that only flat, single-position images were acquired, without a rotational SPECT component. The report should identify the tracer, the gland imaged, and the camera views obtained. A frequent mistake is applying this code when the department actually performed a combined uptake-and-scan visit; the uptake measurement and the imaging are distinct root operations and both must be captured if both were done. Another recurring error is defaulting to "planar" because that is the more familiar term, when the technologist's protocol notes actually describe a SPECT acquisition.
Commonly Confused With
The closest look-alike is Tomographic Nuclear Medicine Imaging of the endocrine system, which differs only in whether the camera rotated to produce 3D reconstructions; dual-phase parathyroid protocols in particular are frequently planar-only despite reports that use the word "tomographic" loosely. It is also confused with Nonimaging Nuclear Medicine Uptake, which measures gland function as a percentage or count rate and produces no picture at all.