Intraoperative ultrasound-directed resection of pituitary tumors

Abstract

Microadenomas of the pituitary vary in size, particularly those related to Cushing's disease. They are often not visualized on preoperative magnetic resonance (MR) imaging and may be difficult to find during surgical exploration of the pituitary. To enhance intraoperative localization of pituitary adenomas, we assessed the feasibility of using ultrasound to detect and localize pituitary tumors. Intraoperative ultrasound (IS) in the axial and sagittal planes was performed with an Intrascan system using a 12-MHz mechanically oscillating, end-firing transducer. Interpretation of the scans was performed by two individuals, who were usually blinded to the results of preoperative MR imaging or petrosal sinus sampling. Twenty-eight patients were examined. Eighteen of these patients had microadenomas (1.5-7 mm), all with Cushing's disease; nine had macroadenomas (10-20 mm), three of which were adrenocorticotropic hormone-secreting, three growth hormone-secreting, two thyroid-stimulating hormone-secreting, and one nonfunctioning; and one patient had an intrasellar craniopharyngioma. Normal sellar and parasellar structures, such as intrapituitary cysts, the intracavernous carotid arteries, and the diaphragma sella were easily visualized. Twenty-three of the 28 tumors, including 13 of the 18 microadenomas, were detected on IS (82% sensitivity). Tumors were seen as hyperechoic masses in 19 patients, mixed echogenicity in three, and isoechoic in one. In most macroadenomas IS allowed visualization of the interface between the tumor and the normal pituitary gland. These results indicate the potential of IS to aid the intraoperative localization and definition of pituitary tumors.

Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics

“…Intraoperative ultrasound during transsphenoidal surgery has been reported by several surgical centers to be valuable in tumor localization in patients with microadenomas and extent of tumor resection in macroadenomas [88][89][90][91][92][93]. Recently, low-field intraoperative MRI was developed to facilitate assessment of extent of tumor resection before the patient is awakened from anesthesia [94][95][96].…”

Volumetric Measurement for Comparison of the Accuracy between Intraoperative CT and Postoperative MR Imaging in Pituitary Adenoma Surgery

“…Ultrasonography has been used recently to detect both micro-and macroadenomas during trans-sphenoidal surgery. 7,8 The implementation of iMR imaging in standard neurosurgical procedures has been widely appreciated because of its ability to immediately control tumor resection. In addition, it offers more accurate intraoperative lesion localization and assessment of tumor resection, which allows intraoperative modification of the surgical strategy.…”

“…4,5 Intraoperative imaging procedures have been devised in an attempt to increase the effectiveness of the surgery, including plain x-ray, fluoroscopy, ultrasonography, iCT, and iMR imaging. [6][7][8][9] Plain xray and fluoroscopy are limited to defining bony anatomy, usually in a single plane, and they are primarily helpful in identifying the floor of the sella turcica. Ultrasonography has been used recently to detect both micro-and macroadenomas during trans-sphenoidal surgery.…”

Intraoperative MRI in transsphenoidal surgery

“…Preoperative diagnostic measures routinely consist of a CT scan and an MRI of the sellar region for visualization of the paranasal sinuses and the tumor and for data acquisition for intraoperative measures such as neuronavigation and intraoperative MRI (iMRI); an endocrine workup; and in some instances blood sampling from the inferior petrosal sinuses with an associated venography. Intraoperative diagnostic measures may consist of fluoroscopy, neuronavigation, intraoperative ultrasound [3], intraoperative inferior petrosal sinus sampling [2], endoscopy, intraoperative frozen sections for histology, or iMRI. Currently, there are two different iMRI techniques in use: low-field iMRI and high-field iMRI.…”