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 mm3 and 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.

iMRI During Transsphenoidal Surgery

“…69 We tested the ESC in cadavers using an existing iMRI system (1.5 T, Achieva, Phillips Healthcare) and demonstrated that SNR values 5 – 12 (mean 10.9 ± 1.6) times those achievable with conventional surface coils. We also showed that ultra-high resolution imaging of the sella (voxel size = 0.15 × 0.15 × 0.3 mm 3 ) could be achieved within a reasonable image acquisition time (~ 6 minutes).…”

Pituitary adenomas: current principles of diagnosis and treatment

“…По данным обзора P. S. Jones и B. Swearingen, обобщивших результаты наиболее крупных исследований и собственные данные, применение МРТ во время операции повышает вероятность радикальной резекции и позволяет прицельно контролировать декомпрессию ключевых функциональных анатомических структур [76]. Использование эндосфеноидальной приемной катушки может существенно улучшить качество интраоперационной визуализации структур селлярной области, в том числе межкавернозных синусов [77].…”

A Miniature Flexible Coil for High-SNR MRI of the Pituitary Gland

“…One example in clinical use, the endorectal coil designed for prostate imaging [12], has had limited use due to patient discomfort related to the relatively large diameter of the endorectal component. Chittiboina et al [13] adopted the endorectal prostate coil for pituitary imaging. The study demonstrated a potential 10-fold increase in SNR by positioning the coil apparatus within the sphenoid sinus via a sublabial approach in a cadaver [13].…”

“…Chittiboina et al [13] adopted the endorectal prostate coil for pituitary imaging. The study demonstrated a potential 10-fold increase in SNR by positioning the coil apparatus within the sphenoid sinus via a sublabial approach in a cadaver [13]. However, the design included a potential concern that the coil is needed to be positioned blindly, given the complete obstruction of the surgical corridor by the probe.…”