title: Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery.
abstract: OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm3and 0.15 × 0.15 × 0.30 mm3, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary adenomas and identify microscopic invasion of the dura or cavernous sinus.
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.
authors.forename: Prashant
authors.initials: P
authors.lastname: Chittiboina
authors.affiliation: NIH MRI Research Facility.
authors.forename: S Lalith
authors.initials: SL
authors.lastname: Talagala
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke; and.
authors.forename: Hellmut
authors.initials: H
authors.lastname: Merkle
authors.affiliation: NIH MRI Research Facility.
authors.forename: Joelle E
authors.initials: JE
authors.lastname: Sarlls
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.
authors.forename: Blake K
authors.initials: BK
authors.lastname: Montgomery
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Piazza
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.
authors.forename: Gretchen
authors.initials: G
authors.lastname: Scott
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.
authors.forename: Abhik
authors.initials: A
authors.lastname: Ray-Chaudhury
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.|Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio; and.
authors.forename: Russell R
authors.initials: RR
authors.lastname: Lonser
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke.|Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Oldfield
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke; and.
authors.forename: Alan P
authors.initials: AP
authors.lastname: Koretsky
authors.affiliation: Radiology and Imaging Sciences, the National Institutes of Health, Bethesda, Maryland.
authors.forename: John A
authors.initials: JA
authors.lastname: Butman
mesh_terms: D002102:Cadaver; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D016343:Monitoring, Intraoperative / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods; D010902:Pituitary Gland / Q000000981:diagnostic imaging* / Q000601:surgery*; D013101:Sphenoid Sinus
keywords: BFFE = balanced fast field echo; CD = Cushing's disease; ESC = endosphenoidal coil; FFE = fast field echo; ROI = region of interest; SE = spin echo; SNR = signal-to-noise ratio; T1-FFE = T1-weighted fast field echo; TSE = turbo spin echo; TSS = transsphenoidal surgery; endosphenoidal coil; iMRI = intraoperative MRI; iUSG = intraoperative ultrasonography; intraoperative magnetic resonance imaging; pituitary adenoma; pituitary surgery; transsphenoidal surgery