Pituitary Macroadenoma Grading Using Magnetic Resonance Imaging: A Sipap Classification Study

Abstract

BACKGROUND: Magnetic resonance imaging (MRI), which is the recommended technique, is often used to identify pituitary adenomas. All pituitary adenomas, with the probable exception of prolactinoma, must initially undergo surgery. As a result, choosing the best surgical strategy and ensuring the safest possible outcome during excision need a straightforward and reproducible MRI classification based on the primary routes of cancer growth. Based on the KNOSP-STEINER categorization of parasellar development, which now includes a classification for posterior, superior, anterior, and inferior tumour extension, the SIPAP MRI categorization for pituitary adenomas was developed.

OBJECTIVE: We thus advocate including the SIPAP classification in the standardized reporting format for pituitary adenomas in order to offer the best imaging definition of the tumour’s delineation, connection to tumour size and juxtasellar structure. As a result, surgical procedures and subsequent clinical treatment will have a better success rate.

METHODS: 49 patients with histopathology pituitary macroadenoma had their imaging retrospectively examined by two radiologists, who used the SIPAP approach to evaluate the outcomes. The study was carried out at Mayo Hospital from December 1, 2021, to November 30, 2022. Stata version 15 was used to analyze the data. Cohen's Kappa was used to determine interobserver variability. The Chi-square test was used to evaluate grades before and after therapy. In statistics, P values ≤ 0.05 were regarded as significant.

RESULTS: The patient population was 63% male and 37% female. 71.82 cm3 and 49.50 cm3 respectively were the largest preoperative and postoperative volumes. With a mean of 14.1 and a standard deviation of 17.7 compared to a mean of 4.5 and a standard deviation of 10.4, pre- and postoperative volumes were significantly different, with a p-value of less than 0.001. The length that differed most noticeably between pre- and post-operative lengths had a mean value of 2.4 and a standard deviation of 1.1 compared to a mean value of 1.3 and a standard deviation of 1.1, with a p-value less than 0.001. The pre-and post-operative SIPAP grading of each tumour extension varied significantly, with the exception of the anterior extension. Prior to surgery, 67.3% of patients had grade 3 suprasellar extension, but thereafter, 63.3% had grade 0. Prior to surgery, grade 2 was present in 51.0% of patients with intrasellar extension, whereas grade 0 was present in 71.4%. Grade 0 anterior, posterior, and parasellar extensions occurred more often postoperatively as compared to preoperatively. All Kappa statistical values exceeding 0.7 (p-value less than 0.001) indicated strong inter-observer agreement for the inferior, anterior, posterior, and superior extents.

CONCLUSIONS: We suggest adopting the straightforward and objective SIPAP categorization into standard MR reporting for the identification of the optimal pituitary tumour, its association with juxtasellar structures, and the tumour size.