Delineation of the internal iliac vein using MRI with true FISP sequence in patients with locally recurrent rectal cancer: A pilot study using CT/MRI fusion.

Purpose: This study assessed the feasibility of using three-dimensional (3D) models of intrapelvic vascular patterns constructed using computed tomography (CT) and magnetic resonance imaging (MRI) fusion data for preoperative planning in patients with locally recurrent rectal cancer.

Methods: Eleven patients scheduled for pelvic exenteration were included. The 3D fusion data of the intrapelvic vessels constructed using CT and MRI with true fast imaging with steady-state precession sequence (True FISP) were evaluated preoperatively. Contrast ratios (CR) between the piriformis muscle and the intrapelvic vessels were calculated to identify a valid modality for 3D modeling and creating CT/MRI fusion-reconstructed volume-rendered images.

Results: The CR values of the internal and external iliac arteries were significantly higher on CT images than MR images (CT vs. MRI; 0.63 vs. 0.45, p < 0.01). However, the CR value of the internal iliac vein was significantly higher on MR than CT images (CT vs. MRI; 0.23 vs. 0.55, p < 0.01).

Conclusions: MRI with True FISP yielded high signal-to-noise ratios and aided in delineating the internal iliac vein around the piriformis muscle. More precise 3D models can be constructed using this technique in the future to aid in the resection of locally recurrent rectal cancer.