Measurement of the normal feline pituitary gland in brachycephalic and mesocephalic cats

Objectives The purpose of this study was to determine differences in normal feline pituitary dimensions in brachycephalic and mesocephalic cats as a basis for establishing cryohypophysectomy in cats. Methods Measurements were performed on sagittal T2-weighted and transverse post-gadolinium T1-weighted or T1 3D fast field echo-weighted MRI images. A total of 32 brachycephalic and 27 mesocephalic cats were examined. Inter-observer reproducibility was assessed by t-test and Bland-Altman analysis. Results The cats were 0.6-15.9 years of age with a body weight range of 1.84-6.60 kg. For brachycephalic cats, the mean pituitary gland sagittal height was 2.15 ± 0.15 mm, pituitary gland transverse height was 2.42 ± 0.21 mm, pituitary gland transverse width was 4.44 ± 0.27 mm and pituitary gland sagittal length was 3.14 ± 0.30 mm. In mesocephalic cats, the pituitary gland dimensions were 2.94 ± 0.16 mm, 3.09 ± 0.26 mm, 4.73 ± 0.31 mm and 4.88 ± 0.30 mm for pituitary gland sagittal height, transverse height, transverse width and sagittal length, respectively. There was a highly significant correlation between brachycephalic and mesocephalic cats and pituitary gland height and length ( P <0.0001), respectively. Sex also had an effect on pituitary gland measurements. Neutering status had no significant effect on hypophyseal measurements. Age had a significant influence on pituitary gland height, width and length in the brachycephalic population. Inter-observer reproducibility was good to excellent. Conclusions and relevance The different pituitary measurements in brachycephalic and mesocephalic cats has to be considered if surgery comes into question. There are ranges in pituitary gland sizes, even among the mesocephalic cat population. Thus, exact measuring of the pituitary gland is crucial before any surgical intervention.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Preoperative Imaging Assessment of Patients With Suspected Nonfunctioning Pituitary Adenomas

BACKGROUND

The authors reviewed published articles pertaining to the preoperative imaging evaluation of nonfunctioning pituitary adenomas (NFPAs) and formulated recommendations.

OBJECTIVE

To provide an exhaustive review of published articles pertaining to the preoperative imaging evaluation of nonfunctioning pituitary adenomas.

METHODS

The MEDLINE database was queried for studies investigating imaging for the preoperative evaluation of pituitary adenomas.

RESULTS

From an initial search of 5598 articles, 122 articles were evaluated in detail and included in this article. Based on analysis of these articles, the recommendations are as follows: (1) High-resolution magnetic resonance imaging (level II) is recommended as the standard for preoperative assessment of nonfunctioning pituitary adenomas, but may be supplemented with CT (level III) and fluoroscopy (level III). (2) Although there are promising results suggesting the utility of magnetic resonance spectroscopy, magnetic resonance perfusion, positron emission tomography, and single-photon emission computed tomography, there is insufficient evidence to make formal recommendations pertaining to their clinical applications.

CONCLUSION

The authors identified 122 articles that form the basis of recommendations for preoperative imaging evaluation of nonfunctioning pituitary adenomas. The full guidelines document for this chapter can be located at https://www.cns.org/guidelines/guidelines-management-patients-non-functioning-pituitary-adenomas/Chapter_2.

ABBREVIATIONS

CT, computed tomographyDWI, diffusion-weighted imagingMRI, magnetic resonance imagingNFPA, nonfunctioning pituitary adenoma.

Magnetic resonance imaging of cavernous sinus invasion by pituitary adenoma diagnostic criteria and surgical findings

This study used MRI to define preoperative imaging criteria for cavernous sinus invasion (CSI) by pituitary adenoma (PA). MR images of 103 patients with PA submitted to surgery (48 with CSI) were retrospectively reviewed. The following MR signs were studied and compared to intraoperative findings (the latter were considered the gold standard for CSI detection): presence of normal pituitary gland between the adenoma and CS, status of the CS venous compartments, CS size, CS lateral wall bulging, displacement of the intracavernous internal carotid artery (ICA) by adenoma, grade of parasellar extension (Knosp-Steiner classification) and percentage of intracavernous ICA encased by the tumor. Statistical analysis was performed using qui-square testing and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were obtained for each MR finding. The following signs have been found to represent accurate criteria for non-invasion of the CS: 1- normal pituitary gland interposed between the adenoma and the CS (PPV, 100%); 2- intact medial venous compartment (PPV, 100%); 3- percentage of encasement of the intracavernous ICA lower than 25% (NPV, 100%) and 4- medial intercarotid line not crossed by the tumor (NPV, 100%). Criteria for CSI were: 1- percentage of encasement of the intracavernous ICA higher than 45%; 2- occlusion of three or more CS venous compartments and 3- occlusion of the CS lateral venous compartment. The CS was very likely to be invaded if the inferior venous compartment was not detected (PPV. 92,8%), if the lateral intercarotid line was crossed (PPV. 96,1%) or if a bulging lateral dural wall of the CS was seen (PPV, 92,3%). The preoperative diagnosis of CSI by PA is extremely important since endocrinological remission is rarely obtained after microsurgery alone in patients with invasive tumors. The above mentioned MR imaging criteria may be useful in advising most of the patients preoperatively on the potential need for complimentary therapy after surgery.

Dynamic magnetic resonance imaging of the normal canine pituitary gland

The pituitary glands of six normal dogs were evaluated using dynamic magnetic resonance imaging. T1 weighted images were obtained every 13 seconds for three minutes of three contiguous slices through the pituitary gland following a bolus intravenous injection of gadolinium-DTPA. Contrast enhancement was seen initially in the region of the pituitary stalk at 52-65 seconds followed by uniform enhancement at 104-143 seconds post injection. This pattern of enhancement was seen in all subjects and is similar to that reported in humans.