Ct and Mri Evaluation of Skull Bones and Soft Tissues in Six Cats With Presumed Acromegaly Versus 12 Unaffected Cats

Abstract

Feline acromegaly is predominantly caused by an adenoma of the pituitary gland, resulting in excessive growth hormone and insulin-like growth factor (IGF-1) secretion. In advanced cases, cats will display prominent facial features and upper airway congestion secondary to bony and soft tissue proliferation. The purpose of this study was to describe CT and MRI characteristics of soft tissues and skull bones in six cats with presumed acromegaly and to compare findings with those observed in 12 unaffected cats. In the five acromegalic cats with CT or MRI evidence of a pituitary tumor, frontal bone thickness was greater than age-matched controls with and without a history of upper airway disease. These five cats also had evidence of soft tissue accumulation in the nasal cavity, sinuses, and pharynx. One cat with insulin-resistant diabetes mellitus, elevated IGF-1, and a normal pituitary size did not have evidence of frontal bone thickening or upper airway congestion.

Computed tomographic signs of acromegaly in 68 diabetic cats with hypersomatotropism

“…These findings, which represent signs of feline acromegaly, are in agreement with previous reports. 7,12 Inclusion of a larger number of subjects in the present study enabled more powerful statistical testing of differences between affected and control cats. The crosssectional area of the nasopharynx is reduced (depth 3.6 mm, width 8.5 mm).…”

“…It seems likely that average head width in entire male cats will be greater than in neutered male cats, and hence the overlap between normal entire male cats and male cats with hypersomatotropism may be greater, further reducing sensitivity of this test. The site of measurement chosen for head width measurement in the present study was that used by previous investigators 12 to measure the frontal bone thickness. This site does not correspond to the maximal head width, which is 1-2 cm further caudal.…”

“…We included this measurement in an attempt to address a limitation in assessing the mandible identified by other investigators. 12 In retrospect, clinical assessment of prognathia may be sufficiently accurate that there is no advantage for CT. Although the observed prevalence of prognathia inferior (24%) was significantly greater than in control cats, it is less than in earlier studies, 4,5 in which prognathia inferior affected 10/14 (71%) and 8/17 (47%) cats, respectively.…”

“…8,9 Computed tomography (CT) and magnetic resonance imaging (MRI) have been used to document the presence of pituitary tumours in cats with insulin-resistant diabetes mellitus and/or hypersomatotropism. 5,[10][11][12] In addition to pituitary morphology, a recent report described CT findings compatible with acromegaly affecting the head in six cats with hypersomatotropism. 12 These signs included thickening of the frontal and parietal bones, thickening of the lining of the nasal cavity and paranasal sinuses, thickening of soft tissue around the pharynx and subcutaneous thickening.…”

“…12 These signs included thickening of the frontal and parietal bones, thickening of the lining of the nasal cavity and paranasal sinuses, thickening of soft tissue around the pharynx and subcutaneous thickening. 12 The aim of the present study was to describe in more detail the signs of acromegaly based on CT scans of a larger series of cats with hypersomatotropism.…”