The MR Imaging Appearance of the Vascular Pedicle Nasoseptal Flap

Abstract

BACKGROUND AND PURPOSE:Recently, surgeons have used an expanded endonasal surgical approach (EENS) to access skull base lesions not previously accessible by minimally invasive techniques. Reconstruction of the large skull base defects created during EENS is necessary to prevent postoperative CSF leaks. A vascular pedicle nasoseptal mucoperiosteal flap based on the nasoseptal artery, (Hadad-Bassagasteguy flap) is becoming a common reconstructive technique. The purpose of this study was to review the expected MR imaging appearance of these flaps and to discuss variations in the appearance that may suggest potential flap failure.

MR Imaging Evolution of Endoscopic Cranial Defect Reconstructions Using Nasoseptal Flaps and Their Distinction from Neoplasm

“…13,14 Kang et al 13 reported NSFs used to reconstruct defects following resection of pituitary adenomas and found stable signal intensity but variable changes in thickness and enhancement of NSFs on follow-up MRI at 3-7 months. 13 They described 2 flaps without enhancement in the immediate postoperative period that showed delayed enhancement on follow-up imaging and 8 flaps that enhanced in the immediate perioperative period with persistent enhancement in 7/8 flaps on follow-up imaging. Five of the initially enhancing NSFs became thinner; 2, thicker; and the average flap thickness varied from nonvisualization to 7 mm.…”

“…Larger, extended cranial defects may require harvesting of bilateral nasoseptal flaps from both sides of the nasal septum and additional free mucosal grafts to cover the entire defect. Kang et al 13 described the MR imaging appearance of ESBR using NSFs to repair the surgically created skull base defects in a small cohort of patients following transsphenoidal resection of pituitary adenomas. 13 Recently, Learned et al 14 reported the immediate postoperative MR imaging evaluation of ESBR utilizing NSFs in a spectrum of sinonasal and skull base tumors resected using EEAs with defects along the entire ventral skull base.…”

“…Kang et al 13 described the MR imaging appearance of ESBR using NSFs to repair the surgically created skull base defects in a small cohort of patients following transsphenoidal resection of pituitary adenomas. 13 Recently, Learned et al 14 reported the immediate postoperative MR imaging evaluation of ESBR utilizing NSFs in a spectrum of sinonasal and skull base tumors resected using EEAs with defects along the entire ventral skull base. In the immediate postoperative period, NSFs have a C-shaped configuration on coronal and/or sagittal planes and avid enhancement, with the associated free grafts closely abutting the NSFs and showing no enhancement.…”

“…In the immediate postoperative period, NSFs have a C-shaped configuration on coronal and/or sagittal planes and avid enhancement, with the associated free grafts closely abutting the NSFs and showing no enhancement. 13,14 Follow-up MR imaging is routinely performed for neoplastic surveillance in patients following EEA skull base resections and reconstructions. The normal evolution of the multilayer reconstructions following EEA is not well understood and can be mistaken for recurrent or persistent tumor.…”

Postoperative Findings in Endoscopic Endonasal Surgery of The Skull Base

“…And on T2-weighted images, water also has a long relaxation time and is seen as high signal intensity (''bright'') [46]. Kang et al [47] studied ten patients who underwent endoscopic surgery of the skull base and required reconstruction of the skull base defect by a nasoseptal flap, all patients were evaluated with MRI, and it was concluded that a vital flap is hypo intense on both T1 and T2 and in both phases of the MRI (immediate and delayed). Regarding inflammatory tissue differentiation, it is important to distinguish between the presence of the inflammatory process due to the surgery, the presence of granulations, and the presence of tumour recurrence.…”