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Computed tomographic densitometry of normal feline thyroid glands
Wm Tod Drost1, John S Mattoon, Valerie F Samii
1Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH 43210, USA.
Summary
Normal feline thyroid tissue is easily detected on computed tomographic (CT) scans without contrast medium. This study determined Hounsfield units for normal thyroid tissue, aiding in CT evaluations of feline thyroid conditions.
Area of Science:
- Veterinary Radiology
- Comparative Anatomy
Background:
- Computed tomography (CT) is crucial for diagnosing feline thyroid abnormalities.
- Establishing baseline CT values for normal feline thyroid tissue is essential for accurate interpretation.
Purpose of the Study:
- To characterize the computed tomographic (CT) appearance and Hounsfield unit (HU) values of normal feline thyroid tissue.
- To compare the attenuation of normal thyroid tissue with surrounding structures before and after contrast medium administration.
Main Methods:
- Helical CT scans were acquired in eight cats from C2 to C4, before and after contrast medium administration.
- Attenuation values (HU) of the thyroid lobes were measured using circular regions of interest.
- Thyroid tissue attenuation was compared to surrounding soft tissues and contrast-enhanced blood vessels.
Main Results:
- Normal feline thyroid tissue was consistently hyperattenuating to surrounding soft tissues on precontrast CT scans (123.2 HU).
- Postcontrast enhancement increased thyroid tissue attenuation, becoming isoattenuating to contrast-laden vessels after delayed enhancement and hypoattenuating after immediate enhancement.
- Thyroid glands appeared ovoid, dorsolateral to the trachea, with homogeneous enhancement.
Conclusions:
- Normal feline thyroid tissue is readily identifiable on non-contrast CT scans.
- The determined Hounsfield unit ranges provide valuable reference data for CT evaluation of feline thyroid pathology.