THYROID SCINTIGRAPHY FINDINGS IN 2096 CATS WITH HYPERTHYROIDISM

Thyroid scintigraphy is currently the reference standard for diagnosing and staging cats with hyperthyroidism, but few studies describing the scintigraphic characteristics in a large number of cats have been reported. The objective of this study was to better characterize thyroid scintigraphy findin...

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Bibliographic Details
Published in:Veterinary radiology & ultrasound 2015-01, Vol.56 (1), p.84-95
Main Authors: Peterson, Mark E., Broome, Michael R.
Format: Article
Language:English
Subjects:
Animals
cat
Cat Diseases - diagnostic imaging
Cats
feline
Female
hyperthyroidism
Hyperthyroidism - diagnostic imaging
Hyperthyroidism - veterinary
Male
Mediastinal Diseases - diagnostic imaging
Mediastinal Diseases - veterinary
Prospective Studies
Radionuclide Imaging
Radiopharmaceuticals
Salivary Glands - diagnostic imaging
scintigraphy
Sodium Pertechnetate Tc 99m
thyroid
Thyroid Dysgenesis - diagnostic imaging
Thyroid Dysgenesis - veterinary
Thyroid Gland - diagnostic imaging
Thyroid Neoplasms - diagnostic imaging
Thyroid Neoplasms - veterinary
Tongue Diseases - diagnostic imaging
Tongue Diseases - veterinary
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Summary:Thyroid scintigraphy is currently the reference standard for diagnosing and staging cats with hyperthyroidism, but few studies describing the scintigraphic characteristics in a large number of cats have been reported. The objective of this study was to better characterize thyroid scintigraphy findings by evaluating 2096 consecutive cats with hyperthyroidism that were referred over a 3.5‐year period. Of these cats, 2068 (98.7%) had a high thyroid‐to‐salivary ratio (>1.5), whereas 2014 (96.1%) were found to have a high thyroid‐to‐background ratio (>6.1). When the patterns of the cats’ thyroid disease were recorded, 665 (31.7%) had unilateral disease, 1060 (50.6%) had bilateral‐asymmetric disease (two thyroid lobes unequal in size), 257 (12.3%) had bilateral‐symmetric disease (both lobes similar in size), and 81 (3.9%) had multifocal disease (≥3 areas of increased radionuclide uptake). The number of areas of 99mTcO−4 uptake in the 2096 cats ranged from 1 to 6 (median, 2), located in the cervical area in 2057 (98.1%), thoracic inlet in 282 (13.5%), and in the thoracic cavity in 115 (5.5%). Ectopic thyroid tissue (e.g. lingual or mediastinal) was diagnosed in 81 (3.9%) cats, whereas thyroid carcinoma was suspected in 35 (1.7%) of the cats. The results of this study support conclusions that most hyperthyroid cats have unilateral or bilateral thyroid nodules, but that multifocal disease will develop in a few cats that have ectopic thyroid disease or thyroid carcinoma. Both ectopic thyroid disease and thyroid carcinoma are relatively uncommon in hyperthyroid cats, with a respective prevalence of ∼4% and ∼2% in this study.
ISSN:1058-8183
1740-8261
DOI:10.1111/vru.12165