Challenges and opportunities for new intraoperative optical techniques in the surgical treatment of pituitary adenomas: a review

Abstract

Significance: Surgery is a common intervention for patients with pituitary adenomas, particularly those experiencing endocrine symptoms or mass effect. Persistent challenges in pituitary surgery include the detection of small microadenomas, difficulty in discerning residual tumor from normal gland, and infiltrative adenomas. Although standard perioperative diagnostics include magnetic resonance imaging (MRI), computed tomography, ultrasound imaging, and neuronavigation, some centers employ intraoperative MRI, ultrasound, and fluorescence-guided endoscopy to increase the rate of gross total resection and preserve pituitary function. However, these techniques are often limited by availability, time requirements, cost, and inability to provide histological diagnosis.

Aim: This review addresses opportunities to optimize both the extent of resection and gland preservation in pituitary adenoma procedures. We discuss the existing constraints faced in pituitary surgery and showcase the current and emerging detection techniques employed in clinical practice, as well as their limitations. We also discuss newer probing approaches such as elastography and Raman spectroscopy.

Approach: We outline key attributes for an ideal optical tool, considering surgical theater functionality, ergonomics, and result reliability and accuracy.

Results: A case study is presented describing the recent development of a fiber-optics instrument specifically designed for endonasal applications based on clinical requirements, along with preliminary data supporting the feasibility of intraoperative implementation.

Conclusions: Current imaging and navigation tools, although invaluable, have inherent limitations in resolution, integration, and molecular specificity. Raman spectroscopy offers a promising, label-free method for real-time tissue identification, especially when integrated into fiber-optic probes for endonasal use. As a complementary tool, it could enhance intraoperative decision-making and surgical precision. Further clinical validation is needed to support its integration into standard workflows.

Keywords: Raman spectroscopy; clinical translation; instrumentation; neurosurgery; pituitary adenoma; tissue optics.

Fig. 1

Illustrative case of a 40-year-old man with a pituitary macroadenoma found incidentally. There was radiological chiasmatic compression without signs or symptoms of optic neuropathy. (a) Preoperative T2-weighted MRI in coronal view of the macroadenoma pushing the pituitary gland to the left. (b) Postoperative T1-weighted MRI with contrast in coronal view. (c) Anterior view of a 3D model of the macroadenoma on the surgical navigation system from the T1-weighted MRI with contrast. (d) Endoscopic endonasal view at the end of the resection showing the pituitary gland displacement to the left and free fat graft used for closure. The interface between the tumor and the gland was visualized, and the gland was preserved to avoid postoperative endocrine deficits. ICA, internal carotid artery.

Fig. 2

Illustrative case of a 57-year-old woman presenting with acromegaly. The patient was referred to neurosurgery for a pituitary microadenoma secreting growth hormone. (a) Preoperative T1-weighted MRI with contrast in coronal view of the microadenoma. (b) Postoperative T1-weighted MRI with contrast in coronal view. (c) Endoscopic endonasal view of microadenoma excision in the pseudocapsular plane. (d) Visualization of the tumor margin during dissection. Histopathological analysis of the specimen confirmed the diagnosis of a growth hormone (GH)-secreting adenoma, and the postoperative course was notable for complete remission of the acromegaly. ICA, internal carotid artery.

Fig. 3

Illustrative case of a 36-year-old man referred for Cushing’s disease. (a) Preoperative T1-weighted MRI with contrast in coronal view showing a pituitary macroadenoma extending inferiorly and toward the left internal carotid artery. (b) Antero-lateral view of a 3D model of the macroadenoma in relation to the internal carotid arteries and pituitary gland. This model was made with the surgical navigation system from the T1-weighted MRI with contrast. (c) Endoscopic endonasal view of macroadenoma resection. (d)–(f) The bottom three images in the figure represent resection steps of the medial wall of the cavernous sinus due to radiological signs of cavernous sinus invasion. The medial wall incision of the cavernous sinus is performed (e), followed by its excision (e), then by post-excision visualization (f). Postoperative pathological analysis confirmed the tumor invasion of the cavernous sinus. Intraoperative confirmation of this tumor invasion would have provided an additional argument justifying excision of the medial wall of the cavernous sinus. The patient remains in remission as of the last follow-up (18 months postoperatively). ICA, internal carotid artery.

Fig. 4

Illustrative case of a 69-year-old woman with a pituitary microadenoma causing acromegaly. (a) Preoperative T1-weighted MRI with contrast in coronal view of the microadenoma near the right cavernous sinus. (b) Anterior view of a 3D model of the microadenoma lining the medial wall of the cavernous segment of the internal carotid artery. This model was made with the surgical navigation system from the T1-weighted MRI with contrast. (c) Endoscopic endonasal view of the dura mater of the sella turcica. The tumor is visualized, and the planned cavernous sinus incision is marked in blue. (d) Visualization of the opening of the right cavernous sinus. (e) Extracapsular dissection of the tumor. (f) Excision of the medial wall of the right cavernous sinus. Pathology confirmed that the tumor was a pituitary adenoma that did not infiltrate the cavernous sinus despite its proximity. A tool allowing assessment of the presence of neoplastic cells intraoperatively would have made it possible to demonstrate the absence of infiltration of the cavernous sinus before its resection. ACA, anterior cerebral artery. ICA, internal carotid artery.

Fig. 5

(a) Handheld Raman spectroscopy probe specifically designed for use during endonasal surgery. (b) Raman spectroscopy system equipped with the endonasal probe. (c) Ex vivo Raman spectroscopy measurement performed in situ on the pituitary gland of a lamb with the designed probe. (d) Average Raman spectra for each lamb tissue type, with corresponding variance computed for each spectral bin across measurements in light grey. Each spectrum is averaged on more than 20 different measurement locations per tissue type.