Planar and single‐photon emission computed tomography imaging in dogs with thyroid tumors: 68 cases

Abstract

Background: Information on scintigraphy findings in dogs with thyroid neoplasia is scarce. The use of single-photon emission computed tomography (SPECT) could improve detection of metastatic disease. Hypothesis/Objectives: To describe planar and SPECT imaging findings in dogs with thyroid tumors, and to compare SPECT and thoracic radiography for metastasis detection. Animals: Sixty-eight dogs with thyroid neoplasia. Methods: Retrospective study, search of medical records for dogs with thyroid neoplasia (2008-2018). Results: Thyroid scintigraphy was available from 68 dogs, of which 6 presented after surgical resection. Radionuclide uptake was increased in 56% of dogs, decreased in 24%, and comparable to that of the salivary glands in 13%. The remainder had multiple masses with variable uptake. A homogeneous uptake pattern was present in 16% and a heterogeneous uptake pattern in 73%. In 11% (all dogs with multiple masses), various uptake patterns were present. Thyroid tumors were well delineated in 55%. There was a significant association between hormone status and uptake pattern (P = .009), with a heterogeneous uptake pattern in the majority of euthyroid dogs, and hormone status and tumor circumscription (P = .003), with well-circumscribed margins in the majority of hypothyroid and hyperthyroid dogs. Thoracic SPECT imaging was available in 39 dogs and identified metastatic lesions in 15 dogs. Thoracic radiographs were performed in 14 of these dogs, and detected metastases in 3 dogs.

In Vivo Imaging of Thyroid Cancer with 99mTc-TR1401 and 99mTc-TR1402: A Comparison Study in Dogs

“…Dogs often develop spontaneous thyroid cancers with histological features very similar to human follicular cancer, and expressing TSHR. Several authors have investigated thyroid cancer in dogs by nuclear medicine procedures, but scans were limited to SPECT/CT with 123 I, 131 I, or 99m TcO 4 − [ 29 , 30 ]. No data are available about FDG uptake in dogs with thyroid cancer or information about galectin-3 expression in this model for the lack of species-specific galectin-3 mAbs.…”

The role of companion animal models in radiopharmaceutical development and translation

“…This also allows for SPECT or PET imaging of thyroid malignancies using Na[ 123 I]I or Na [ 124 I]I, respectively. [9][10][11] These chemical analogues extend beyond a single isotope, however, as elements within the same group of the periodic table often share many chemical properties. It is this mechanism that allows for the targeting of regions of bone remodelling with agents such as [ 89 Sr]SrCl 2 (Metastron) and [ 223 Ra]RaCl 2 (Xofigo), used to treat metastatic bone cancer.…”

“…22 Despite a low percentage of functional hyperthyroid dogs, nearly 40%-50% of dogs will demonstrate accumulation of radiotracer on pertechnetate or iodine imaging. 10,11 A 1989 case report described the use of 131 I in a dog with a functional thyroid tumour who received three doses of 2220-2775 MBq at 5-7 month intervals, with noted, though transient, tumour response after each treatment. 23 A retrospective paper describing the use of 131 I in the treatment of 65 dogs in Australia delivered one to three doses of 555-1850 MBq either in the single-agent, or as an adjuvant treatment to surgery found prolonged median survival of 30 or 34 months, respectively, significantly longer than those which were untreated (3 months).…”

“…9 SPECT and PET have the advantage of being both more sensitive and providing for a more quantitative assessment of iodine accumulation. 10,11 There is also a report of dosimetry estimates using OLINDA (MIRDOSE3) in 3 normal dogs receiving 1-(2 0 -deoxy-2 0 -18 F-fluoro-1-β-d-arabinofuranosyl)-5-bromouracil ( 18 F-FBAU), a potential PET tracer of DNA synthesis. 51 MIRD-based models were also used to estimate dosimetry and plan therapy using intralesional administration of 166 Ho microspheres in dogs and cats with spontaneously occurring tumours.…”

Application of Advanced Imaging Modalities in Veterinary Medicine: A Review

“…Single-photon emission computed tomography (SPECT) is an important imaging modality for various applications in veterinary medicine. Among its numerous applications, SPECT is useful for noninvasive investigation of renal function in the mouse by means of dynamic imaging, parenchymal scanning, and quantification of filtration, secretion, and reabsorption events, 80 comparison of regional cerebral blood flow (rCBF) in dogs with congenital portosystemic shunt (PSS) and hepatic encephalopathy (HE) with rCBF in healthy control dogs with a 99mtechnetium-hexamethylpropylene amine oxime (99mTcHMPAO) tracer, 81 in vivo assessment of the dopamine transporter (DAT) availability in healthy dogs, 82 non-invasive assessment of neuroinflmmation, blood–brain barrier alterations, and neurotransmitter systems, provision of better insight into the neurobiology of epilepsy in human and dogs that is desirable for veterinary epilepsy patients these promising developments in the medium term, 83–85 to screen thoracic metastasis and is recommended in dogs with thyroid neoplasia, 86 and also used extensively to study cardiac health-like blood flow to the heart through myocardial perfusion imaging and to image blood flow to the brain. 77…”