The Significance of the Intercarotid Distances for Transsphenoidal Pituitary Surgery: A Magnetic Resonance Imaging Study

Abstract

We performed MRI to analyze the distance between the left and right internal carotid arteries (ICD) around pituitary tumors for transsphenoidal surgery (TSS). Measurements were performed using thin slice T2-weighted MRI, and/or time-of-flight MR angiography imaging for 64 non-functioning pituitary neuroendocrine tumors (NF-pitNETs), 22 growth hormone-producing pitNETs (GH producing pitNETs), and 46 normal controls. We measured the ICD at 3 anatomic levels: at the distal dural ring (ICD-A); at the most concave point of the C4-C5 bend (ICD-B); and at the most convex point of the C4 bend (ICD-C). Additionally, we measured the sagittal distance between the tuberculum selle and the junction of the sellar floor and clivus on the mid sagittal MRI (TS-C). We found that ICD-B was the longest and that ICD-A was the shortest among the three distance parameters in all groups (P<0.001). The comparison of the groups revealed that the NF-pitNET group had longer distances than the normal control group at all ICDs (P<0.001). The GH producing pitNET group had longer distance than the normal control group at ICD-B (P<0.001). Tumor volume was correlated with ICD-A and ICD-B in the NF-pitNET, and was correlated with ICD-C in the GH producing pitNET group. Among the distance parameters, ICD-B is the longest, and was approximately twice the width of the TS-C. The shape of the sella is an ellipse that is widest in the lateral dimension in TSS. A horizontal based dural incision may be more rational than a conventional X-shaped dural incision.