Captivating Cases

Issue 18 - August 2015

We are excited to announce the addition of Dr. Ashley Yanchik to the Animal Imaging team!

Dr. Yanchik is a 2001 graduate of the University of Pennsylvania School of Veterinary Medicine. Recently she was employed at a busy equine practice in Lisle, Illinois. We are excited to have Dr. Yanchik's expertise at Animal Imaging to assist in the management of both equine and companion animal cases.

Equipped for Success

Animal Imaging offers virtually every outpatient veterinary diagnostic imaging option available for small animal and equine, all in one location:

CT Scan
Fluoroscopy
MRI (3-Tesla)
Nuclear Medicine
Teleradiology
Ultrasound/Mobile Ultrasound

Nuclear Scintigraphy and CT of the Thyroid Glands

History and clinical complaint:

Luke is a 9-year-old neutered male Boykin Spaniel that presented to Animal Imaging in October 2014 for nuclear scintigraphy of the thyroid glands. He had a history of weight loss, polyuria, and polydipsia. Elevated thyroid levels were found eight months prior to presentation. The prostate was also slightly palpable on rectal examination.

Scintigraphic Findings:

For the thyroid nuclear scintigraphy, 2.24 mCi of technetium was injected intravenously in the right saphenous vein. Images of the neck and thorax were acquired 30 minutes post injection. Thyroid nuclear scintigraphy showed an abnormal region of increased radiopharmaceutical uptake within the cranial ventral mediastinum. In light of the elevated T4 level, location of the lesion, and uptake of the radionuclide, ectopic thyroid tissue (in particular a carcinoma) was the primary differential.

As part of the thyroid scan, survey abdominal and thoracic radiographs were obtained. The right lateral projection of the thorax showed a well-defined rounded soft tissue nodule that summated with the 10th rib overlying the diaphragm. This nodule could have represented a metastatic nodule, but artifact could not be ruled out.

Lateral Nuclear Scintigraphic Image

CT Findings:

Pre-Contrast CT

A CT of the neck, thorax, and abdomen was recommended to better characterize the cranial mediastinal mass prior to surgical planning and to screen for metastasis. The next day, a CT exam of the cervical region, thorax, and abdomen was performed with acquisitions made both pre and post intravenous contrast. The thyroid lobes were found to be small. There was a well-defined soft tissue attenuating mass within the cranial ventral mediastinum measuring 4.4 x 3.7 x 3.1 cm. The majority of the mass showed evidence of strong contrast enhancement. No other significant findings were noted. No evidence of metastasis to the lungs or lymph nodes was evident. Based on the patient's clinical signs, thyroid scintigraphy, and CT examination, the primary differential was ectopic functional thyroid carcinoma.

Post Contrast CT

Conclusion:

Based on the findings of the CT examination, consultation with a surgeon and oncologist was recommended. Surgical removal of the mediastinal mass followed by doxorubicin or I-131 treatment was recommended. In November 2014, the dog underwent surgery to have the cranial mediastinal mass removed. Histopathology confirmed the diagnosis of ectopic thyroid carcinoma.

Outcome:

As suspected, following removal of the ectopic thyroid carcinoma, the patient became hypothyroid and required supplementation with levothyroxine. It is anticipated that he will eventually be weaned off thyroid supplementation as the thyroid glands become more functional, but it may take weeks to months to return to normal.