Diagnostic Accuracy of Non-Contrast Magnetic Resonance Imaging in Diagnosing Pituitary Micro-Adenoma, Taking Histopathology as Gold Standard

Abstract

Background: Pituitary microadenomas (PMs) are common benign tumors that are often not visualized even when they are present due to their asymptomatic nature. The objective of the study was to evaluate the diagnostic accuracy of non-contrast magnetic resonance imaging (MRI) in the diagnosis of pituitary microadenomas using histopathology as a gold standard.

Methods: This cross-sectional validation study (IRB Approval No. IRB/18/2024/01) included 121 patients presenting with severe headaches and focal brain lesions on CT scans at Doctors Hospital, Lahore from September 2024 to November 2024. In this cross-sectional study, a non-probability consecutive sampling technique was used. A standardized protocol was used for non-contrast MRI and findings were interpreted by experienced radiologists. The comparison was made against histopathology as the reference standard. A 2×2 contingency table was used to calculate sensitivity, specificity, positive predictive value and negative predictive value, and overall diagnostic accuracy by using SPSS version 25.

Results: Of 121 patients (mean age 40.74 ± 10.35 years), 70 (57.9%) were females. Non-contrast MRI showed a sensitivity and specificity of 37.25% (38/102) and 89.47% (17/19) respectively. Specificity is high, meaning that the modality is reliable in eliminating false positives, but sensitivity is low, which means that it won’t find true positives correctly. The percentage of diagnostic accuracy was 45.5% (55/121) which showed that the technique had room for significant improvement.

Conclusion: Pituitary microadenomas can be clinicopathologically screened using non-contrast MRI as an initial radiation-free diagnostic modality with minimal ionizing and contrast agents-based risk being valuable for long-term monitoring.