[Differentiating between tumor and implant material in the postoperative sella using MRT]

Area of Science:

• Neurosurgery
• Radiology
• Endocrinology

Background:

• Transsphenoidal hypophysectomy is a common surgical procedure for pituitary tumors.
• Distinguishing between residual tumor and surgical implant material post-operatively can be challenging.
• Accurate postoperative assessment is crucial for patient management and treatment planning.

Purpose of the Study:

• To develop and validate magnetic resonance imaging (MRT) criteria for differentiating pituitary tumor remnants from implant material.
• To assess the diagnostic performance of MRT in identifying residual or recurrent pituitary tumors.
• To provide guidance for the use of MRT in postoperative evaluation of hypophyseal tumors.

Main Methods:

• Retrospective analysis of MRT scans from 50 patients who underwent transsphenoidal hypophysectomy.
• Utilized T1-weighted spin-echo sequences with Gd-DTPA contrast enhancement.
• Correlated MRT findings with postoperative hormonal status and operative notes.

Main Results:

• Implant material typically appeared as sandwich-like, linear, or circular structures.
• Residual/recurrent tumor showed homogenous or non-homogenous patterns without marginal enhancement in 84% of cases.
• Infundibular displacement was observed in 73% of patients with tumor remnants.
• MRT demonstrated a sensitivity of 70%, specificity of 95%, positive predictive value of 94%, and negative predictive value of 72%.

Conclusions:

• Established MRT criteria effectively differentiate tumor remnants from implant material after hypophysectomy.
• MRT is a valuable tool for assessing surgical success and diagnosing residual or recurrent pituitary tumors.
• Recommended for routine use in postoperative evaluation of hypophyseal tumors when clinical doubt exists.