A Comparison between 3 Tesla MRI and 1 to 1.5 Tesla MRI for Sellar Lesions with Special Regard to the Cavernous Sinus

Introduction: The aim is to determine the value of high-field magnetic resonance imaging (MRI) for diagnosis and surgery of sellar lesions and to determine the preoperative predictive value of parasellar invasion into the medial wall of the cavernous sinus using 3 Tesla MRI.

Material and Methods: High-field MRI using a 3 Tesla Bruker Medspec® 30/80 scanner (Bruker and Ettlingen, Germany) with emphasis on sellar and parasellar structures was obtained from 21 patients to verify a pituitary microadenoma that was suspected endocrinologically and/or with conventional 1.0 to 1.5T (standard) MRI, to preoperatively delineate endo-, supra-, and parasellar anatomical structures with special regard to the medial border of the cavernous sinus and a possible invasion of a sellar tumor therein and to assess the application of high-resolution images during intraoperative neuronavigation. 3T MRI was compared to the already available standard MRI (1 to 1.5T) and to intraoperative findings as a reference.

Results: Anatomical structures were studied in all 42 cavernous sinuses; in 32 of them comparison with intraoperative findings was available: The medial cavernous sinus border was rated intact in 53% of standard MRI, in 72% of 3T MRI, and in 81% intraoperatively. With a positive correlation to surgical findings in 84% of 3T MRI compared to 59% of standard MRI, a sensitivity of 83% versus 67% and a specificity of 84% versus 58% (P = 0.016, McNemar test), 3T MRI was superior to standard MRI in predicting tumor invasion through the medial cavernous sinus border. While no difference was noted with the medial, superior, and inferior compartments, there was a better delineation of the lateral cavernous sinus compartment using 3T MRI: it was clearly visible on 40 sides (95%) on 3T MRI versus 34 sides (81%) using standard MRI. Identification of the cavernous sinus segments of the cranial nerves III, IV, V₁, V₂, and VI was improved using high-resolution 3T imaging instead of standard MRI: a mean of 4 cranial nerves as hypointense spots (range: 2–5 spots) was found on 3T MRI versus 3 (range: 0–4) on standard MRI. Intraoperative navigation with fusion of 3T MRI and computed tomography (CT) images was performed in 7 patients and particularly useful for visualization of parasellar tumor extension during microsurgical and/or endoscopic resection.

Conclusions: Due to its higher resolution, 3T MRI was found to be superior to standard MRI for delineation of sellar lesions, parasellar anatomy, and tumor infiltration into the cavernous sinus. 3T MRI was able to visualize parasellar anatomy to such a detailed extent that a medial cavernous sinus border infiltration may be visible, which is particularly important for surgery of laterally invasive sellar lesions. Moreover, 3T MRI provides improved imaging for intraoperative navigation.