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

OBJECTIVE: We performed magnetic resonance imaging (MRI) to analyze the distance between the left and right internal carotid arteries (ICD) around pituitary tumors for transsphenoidal surgery (TSS).METHODS: Measurements were performed using thin slice T2-weighted MRI, and/or time-of-flight (TOI) MR angiography imaging for 64 nonfunctioning 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 dis-tance between the tuberculum selle and the junction of the sellar floor and clivus on the midsagittal MRI (TS-C).RESULTS: We found that ICD-B was the longest and that ICD-A was the shortest among the 3 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 corre-lated with ICD-A and ICD-B in the NF-pitNET, and was correlated with ICD-C in the GH producing pitNET group.CONCLUSIONS: 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.