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

MR Imaging Evolution of Endoscopic Cranial Defect Reconstructions Using Nasoseptal Flaps and... BACKGROUND AND PURPOSE: Endoscopic endonasal approach is the procedure of choice for the resection of ventral skull base neoplasms, with defect closure requiring multilayer reconstruction. This study evaluates the temporal MR imaging evolution of nasoseptal flaps and free grafts used in endoscopic skull base reconstruction. MATERIALS AND METHODS: Sixty-nine follow-up brain MRIs of 22 patients who had endoscopic skull base reconstruction using 26 nasoseptal flaps combined with 8 collagen-matrix dural grafts, 10 fascia lata grafts, and 10 intracranial fat grafts were retrospectively reviewed. Temporal changes in signal intensity, enhancement, thickness, and the configuration of reconstructive layers were evaluated. Tissue with signal intensity or enhancement different from that of normal evolving reconstructive layers at the surgical bed was evaluated, and its association with clinically confirmed tumor was assessed with the Fisher exact test. RESULTS: All normal reconstructive layers were retracted to cranial defects and showed maturation of imaging features within 2–6 months. The immediate postoperative T2-isointensity to brain and enhancement of nasoseptal flaps persisted, but the flap thickness was reduced by 20%–30% (average thickness, 4.5 ± 1.3 mm); additionally, the C shape and vascular pedicle of the nasoseptal flaps became indistinct, but the flap location remained unchanged. The initial appearance of the nonenhancing fascia lata with variable T2 signal intensity became enhancing with increasing T2-hypointensity and a graft-thickness reduction of ≥50% (average thickness, 3.5 ± 1.6 mm). All fat grafts showed progressive resorption. In 6 patients, abnormal tissue represented residual or recurrent tumor ( P = .0001). CONCLUSIONS: Maturation and stability of multilayer endoscopic skull base reconstructions on MR imaging occurs within 2–6 months postoperatively. Understanding of the normal imaging evolution of endoscopic skull base reconstructions is essential to distinguish them from neoplasms. ABBREVIATIONS: ASB anterior skull base CSB central skull base EEA endoscopic endonasal approach ESBR endoscopic skull base reconstruction NSF nasoseptal flap http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Neuroradiology American Journal of Neuroradiology

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

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Publisher
American Journal of Neuroradiology
Copyright
Copyright © 2014 by the American Society of Neuroradiology.
ISSN
0195-6108
eISSN
1936-959X
DOI
10.3174/ajnr.A3853
pmid
24457820
Publisher site
See Article on Publisher Site

Abstract

BACKGROUND AND PURPOSE: Endoscopic endonasal approach is the procedure of choice for the resection of ventral skull base neoplasms, with defect closure requiring multilayer reconstruction. This study evaluates the temporal MR imaging evolution of nasoseptal flaps and free grafts used in endoscopic skull base reconstruction. MATERIALS AND METHODS: Sixty-nine follow-up brain MRIs of 22 patients who had endoscopic skull base reconstruction using 26 nasoseptal flaps combined with 8 collagen-matrix dural grafts, 10 fascia lata grafts, and 10 intracranial fat grafts were retrospectively reviewed. Temporal changes in signal intensity, enhancement, thickness, and the configuration of reconstructive layers were evaluated. Tissue with signal intensity or enhancement different from that of normal evolving reconstructive layers at the surgical bed was evaluated, and its association with clinically confirmed tumor was assessed with the Fisher exact test. RESULTS: All normal reconstructive layers were retracted to cranial defects and showed maturation of imaging features within 2–6 months. The immediate postoperative T2-isointensity to brain and enhancement of nasoseptal flaps persisted, but the flap thickness was reduced by 20%–30% (average thickness, 4.5 ± 1.3 mm); additionally, the C shape and vascular pedicle of the nasoseptal flaps became indistinct, but the flap location remained unchanged. The initial appearance of the nonenhancing fascia lata with variable T2 signal intensity became enhancing with increasing T2-hypointensity and a graft-thickness reduction of ≥50% (average thickness, 3.5 ± 1.6 mm). All fat grafts showed progressive resorption. In 6 patients, abnormal tissue represented residual or recurrent tumor ( P = .0001). CONCLUSIONS: Maturation and stability of multilayer endoscopic skull base reconstructions on MR imaging occurs within 2–6 months postoperatively. Understanding of the normal imaging evolution of endoscopic skull base reconstructions is essential to distinguish them from neoplasms. ABBREVIATIONS: ASB anterior skull base CSB central skull base EEA endoscopic endonasal approach ESBR endoscopic skull base reconstruction NSF nasoseptal flap

Journal

American Journal of Neuroradiology – American Journal of Neuroradiology

Published: Jun 1, 2014

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