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. 2015 Sep;76(5):340-3.
doi: 10.1055/s-0035-1549005. Epub 2015 Apr 27.

Prediction of Consistency of Pituitary Adenomas by Magnetic Resonance Imaging

Kyle A Smith  1 , John D Leever  2 , Roukoz B Chamoun  1
Affiliations

Prediction of Consistency of Pituitary Adenomas by Magnetic Resonance Imaging

Kyle A Smith et al. J Neurol Surg B Skull Base. 2015 Sep.

Abstract

Objective Pituitary adenomas are typically soft. The prevalence of fibrous adenomas is ∼ 5 to 13%. Firm tumors are difficult to remove by curettage or suction. Predicting fibrous adenomas by magnetic resonance (MR) imaging is typically difficult and unreliable. We propose a new prediction method based on MR T2-sequence intensity. Methods The MRIs of 36 consecutive patients with nonsecreting macroadenomas were evaluated preoperatively by a blinded radiologist. Using an MR T2-weighted sequence, regions of interest were sampled from the adenoma and cerebellar peduncle, and the ratio was calculated. Intraoperatively, tumors were graded prospectively for their consistency by the operating surgeon. Results There were 28 soft and 6 fibrous tumors. Unpaired t test for these ratios was found to be statistically significant (p < 0.0240; 95% confidence interval, -0.8229 to -0.06207). Mean values for soft tumors were found to be 1.918 (standard error of the mean [SEM] = 0.08212); firm tumors, 1.475 (SEM = 0.1179). Soft tumors were associated with ratios > 1.5 (sensitivity 100%; specificity 66.7%); firm tumors were associated with ratios < 1.8 (sensitivity 100%; specificity 42.9%). Conclusion Fibrous adenomas are typically diagnosed intraoperatively. However, their resection can be technically challenging. Using T2 intensity ratios on routine preoperative MRI allows identification of these challenging cases. The surgeon can then be better prepared for the surgical resection.

Keywords: MRI; adenoma consistency; endoscopic transsphenoidal; fibrous adenomas; pituitary adenomas.

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Conflict of interest statement

Disclaimer The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this article.

Figures

Fig. 1
Fig. 1
How to use the adenoma- to-cerebellar peduncle ratio. (A) Region of interest (ROI) in adenoma on T2 sequence. (B) ROI in middle cerebellar peduncle on T2 sequence. Calculating the adenoma-to-cerebellar peduncle ratio. Ratio = intensity value for ROI within tumor (A)/Intensity value for ROI within middle cerebellar peduncle (B).
Fig. 2
Fig. 2
Adenoma-to- cerebellar peduncle intensity ratio example. (A) Region of interest (ROI) intensity within tumor = 938.4 (B) ROI intensity within middle cerebellar peduncle = 977.5. ACP ratio = 938.4/977.5 = 0.96.
Fig. 3
Fig. 3
Frequency distribution for adenoma-cerebellar peduncle intensity ratios by consistency.
See this image and copyright information in PMC

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