Intraoperative Real-Time Near-Infrared Image-Guided Surgery to Identify Intracranial Meningiomas via Microscope

Utility of intraoperative fluorescence imaging with indocyanine green for diagnosing spinal schwannoma: A case report

Background

The delayed-window indocyanine green (DWICG) technique is useful for the removal of brain and spinal tumors.

Case Description

A 41-year-old female presented with lower left back and radicular pain. An magnetic resonance imaging (MRI) revealed an extramedullary L3 lesion located ventrally in the spinal canal that appeared to be a schwannoma. Intravenous indocyanine green (dose, 0.25 mg/kg) was administered 1 h before the L2-L4 laminectomy and L3/L4 posterior lumbar fusion. At surgery utilizing a strong near-infrared (NIR) signal, the tumor was clearly visualized through the dura. Complete tumor excision was confirmed when the NIR signal could no longer be detected. Pathologically, the lesion proved to be a schwannoma. A postoperative MRI scan further confirmed complete tumor excision.

Conclusion

In a 41-year-old female, the DWICG technique intraoperatively facilitated localization of a L3 schwannoma through the dura and expedited gross total tumor removal.

Intraoperative near infrared functional imaging of rectal cancer using artificial intelligence methods - now and near future state of the art

Colorectal cancer remains a major cause of cancer death and morbidity worldwide. Surgery is a major treatment modality for primary and, increasingly, secondary curative therapy. However, with more patients being diagnosed with early stage and premalignant disease manifesting as large polyps, greater accuracy in diagnostic and therapeutic precision is needed right from the time of first endoscopic encounter. Rapid advancements in the field of artificial intelligence (AI), coupled with widespread availability of near infrared imaging (currently based around indocyanine green (ICG)) can enable colonoscopic tissue classification and prognostic stratification for significant polyps, in a similar manner to contemporary dynamic radiological perfusion imaging but with the advantage of being able to do so directly within interventional procedural time frames. It can provide an explainable method for immediate digital biopsies that could guide or even replace traditional forceps biopsies and provide guidance re margins (both areas where current practice is only approximately 80% accurate prior to definitive excision). Here, we discuss the concept and practice of AI enhanced ICG perfusion analysis for rectal cancer surgery while highlighting recent and essential near-future advancements. These include breakthrough developments in computer vision and time series analysis that allow for real-time quantification and classification of fluorescent perfusion signals of rectal cancer tissue intraoperatively that accurately distinguish between normal, benign, and malignant tissues in situ endoscopically, which are now undergoing international prospective validation (the Horizon Europe CLASSICA study). Next stage advancements may include detailed digital characterisation of small rectal malignancy based on intraoperative assessment of specific intratumoral fluorescent signal pattern. This could include T staging and intratumoral molecular process profiling (e.g. regarding angiogenesis, differentiation, inflammatory component, and tumour to stroma ratio) with the potential to accurately predict the microscopic local response to nonsurgical treatment enabling personalised therapy via decision support tools. Such advancements are also applicable to the next generation fluorophores and imaging agents currently emerging from clinical trials. In addition, by providing an understandable, applicable method for detailed tissue characterisation visually, such technology paves the way for acceptance of other AI methodology during surgery including, potentially, deep learning methods based on whole screen/video detailing.

Fluorescence in neurosurgery: its therapeutic and diagnostic significance - a comprehensive review

This review provides a comprehensive overview of the therapeutic and diagnostic implications of fluorescence imaging in neurosurgery. Fluorescence imaging has become a valuable intraoperative visualization and guidance tool, facilitating precise surgical interventions. The therapeutic role of fluorescence is examined, including its application in photodynamic therapy and tumor-targeted therapy. It also explores its diagnostic capabilities in tumor detection, margin assessment, and blood-brain barrier evaluation. Drawing from clinical and preclinical studies, the review underscores the growing evidence supporting the efficacy of fluorescence imaging in neurosurgical practice. Furthermore, it discusses current limitations and future directions, emphasizing the potential for emerging technologies to enhance the utility and accessibility of fluorescence imaging, ultimately improving patient outcomes in neurosurgery.

Achieving Gross Total Resection in Neurosurgery: A Review of Intraoperative Techniques and Their Influence on Surgical Goals

The definition of complete resection in neurosurgery depends on tumor type, surgical aims, and postoperative investigations, directly guiding the choice of intraoperative tools. Most common tumor types present challenges in achieving complete resection due to their infiltrative nature and anatomical constraints. The development of adjuvant treatments has altered the balance between oncological aims and surgical risks. We review local recurrence associated with incomplete resection based on different definitions and emphasize the importance of achieving maximal safe resection in all tumor types. Intraoperative techniques that aid surgeons in identifying tumor boundaries are used in practice and in preclinical or clinical research settings. They encompass both conservative and invasive techniques. Among them, morphological tools include imaging modalities such as intraoperative magnetic resonance imaging, ultrasound, and optical coherence tomography. Fluorescence-guided surgery, mainly using 5-aminolevulinic acid, enhances gross total resection in glioblastomas. Nuclear methods, including positron emission tomography probes, provide tumor detection based on beta or gamma emission after a radiotracer injection. Mass spectrometry- and spectroscopy-based methods offer molecular insights. The adoption of these techniques depends on their relevance, effectiveness, and feasibility. With the emergence of positron emission tomography imaging for use in recurrence benchmarking, positron emission tomography probes raise particular interest among those tools. While all such tools provide valuable insights, their clinical benefits need further evaluation.

Intraoperative visualization of cranial nerve schwannomas using second-window indocyanine green: A case series

BACKGROUND

Second Window Indocyanine Green (SWIG) is a novel intraoperative imaging technique that uses near-infrared (NIR) light for intra-operative tumor visualization using the well-known fluorophore indocyanine green (ICG). Because schwannomas often incorporate the nerve into the encapsulated tumor and impinge on surrounding neural structures, SWIG is a promising technique to improve tumor resection while sparing the nerve.

OBJECTIVE

To demonstrate the use of SWIG in resection of cranial nerve schwannomas.

METHODS

Three patients with cranial nerve schwannomas (i.e., trigeminal, vestibular, and vagus) underwent SWIG-guided resection. During surgery, NIR visualization was used intermittently used to detect fluorescence to guide resection. Signal-to-background ratio was then calculated to quantify fluorescence.

RESULTS

Patients were infused with ICG at a dose of 5.0 mg/kg 24 hours before surgery. Each patient achieved total or near-total resection and relief of symptoms with lack of recurrence at six-month follow-up. The average SBR calculated was 3.79, comparable to values for SWIG-guided resection of other brain and spine tumors.

CONCLUSION

This case series is the first published report of trigeminal and vagus nerve schwannoma resection using the SWIG technique and suggests that SWIG may be used to detect all schwannomas, alongside many other types of brain tumor. This paper also demonstrates the importance of preoperative ICG infusion timing and discusses the inverse pattern of NIR signal that may be observed when infusion occurs outside of the optimal timing. This provides direction for future studies investigating the administration of SWIG to resect cranial nerve schwannomas and other brain tumors.

Dielectric Spectroscopy Shows a Permittivity Contrast between Meningioma Tissue and Brain White and Gray Matter-A Potential Physical Biomarker for Meningioma Discrimination

The effectiveness of surgical resection of meningioma, the most common primary CNS tumor, depends on the capability to intraoperatively discriminate between the meningioma tissue and the surrounding brain white and gray matter tissues. Aiming to find a potential biomarker based on tissue permittivity, dielectric spectroscopy of meningioma, white matter, and gray matter ex vivo tissues was performed using the open-ended coaxial probe method in the microwave frequency range from 0.5 to 18 GHz. The averages and the 95% confidence intervals of the measured permittivity for each tissue were compared. The results showed the absence of overlap between the 95% confidence intervals for meningioma tissue and for brain white and gray matter, indicating a significant difference in average permittivity (p ≤ 0.05) throughout almost the entire measured frequency range, with the most pronounced contrast found between 2 GHz and 5 GHz. The discovered contrast is relevant as a potential physical biomarker to discriminate meningioma tissue from the surrounding brain tissues by means of permittivity measurement, e.g., for intraoperative meningioma margin assessment. The permittivity models for each tissue, developed in this study as its byproducts, will allow more accurate electromagnetic modeling of brain tumor and healthy tissues, facilitating the development of new microwave-based medical devices and tools.

Intraoperative Real-Time Near-Infrared Image-Guided Endoscopic Endonasal Surgery for Pituitary Tumors

BACKGROUND

For endoscopic endonasal surgery of pituitary tumors, tissue identification and intraoperative judgment depend largely on surgeon expertise. In the present study, we assess whether the delayed-window indocyanine green (ICG) technique can identify pituitary gland tumors in real-time during surgery and analyze the mechanism of ICG fluorescence in the pituitary gland and tumor.

METHODS

Twenty-five patients with a pituitary adenoma were administered 12.5 mg of ICG intravenously during surgery. Thereafter, near-infrared (NIR) visualization was performed from 0 to 180 minutes. Only 8 patients underwent dynamic contrast-enhanced perfusion magnetic resonance imaging (MRI) owing to predicaments with insurance coverage. Consequently, we analyzed these 8 patients extensively.

RESULTS

The pituitary gland and pituitary adenoma were visualized in all 25 patients with NIR fluorescence. The relative ratio of the fluorescence emission of the normal gland to that of the tumor (signal/background ratio [SBR] of the normal gland vs. the tumor) had increased after 15 minutes, peaking (5.8) at 90 minutes, demonstrating that the pituitary gland was distinctly visualized during that period. The tumor/blood (SBR tumor) and normal gland/blood (SBR gland) NIR fluorescence was significantly and positively correlated with each transfer constant on dynamic contrast-enhanced MRI, indicating vascular permeability.

CONCLUSIONS

The results from the present study exhibit the utility of the delayed-window ICG technique in distinguishing the normal pituitary gland from a tumor during endoscopic endonasal surgery from 15 to 90 minutes after ICG administration. Permeability can contribute to gadolinium enhancement on MRI, as well as ICG retention and NIR fluorescence in a normal pituitary gland and tumor.

[Surgical treatment of large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading]

OBJECTIVE

To investigate the surgical strategy for large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading.

METHODS

The clinical data of 16 patients with large and giant recurrent meningioma in the middle and posterior third part of the superior sagittal sinus with extracranial invasion who underwent surgery in the Department of Neurosurgery of Peking University Third Hospital from May 2019 to May 2022 were retrospectively analyzed. All the patients underwent brain-enhanced magnetic resonance imaging (MRI), magnetic resonance venography (MRV), computed tomography angiography (CTA) and three-dimensional skull computed tomography (CT) before, to evaluate the extent of tumor invasion, the edema of brain tissue, the degree of skull damage, the blood supply of the tumor, and the degree of compression of the superior sagittal sinus, etc, and to formulate an individualized surgical plan. The neurological function of the patients was evaluated 1 week, 1 month, and 3 months after the operation, and the tumor condition was evaluated by brain-enhanced MRI 3 months, 6 months, and 1 year after the operation.

RESULTS

The tumors in the 16 patients were all located in the middle and posterior 1/3 part of the superior sagittal sinus and invaded extracranially. Among them, 8 cases were operated for the second time, 6 cases for the third time, and 2 cases for the fourth time; In the last operation, the bone flap was used to repair the skull in 4 cases, and the titanium mesh was used in 12 cases; Tumor arterials of 3 cases were embolized under digital subtraction angiography (DSA). Tumors of 10 cases were resected at Simpson grade Ⅰ, and 6 cases at Simpson grade Ⅱ; 2 cases underwent decompressive craniectomy during operation, and 14 cases underwent cranioplasty at the same time; scalp incisions of 14 cases were directly sutured, and flap transposition was used in 14 cases. When evaluating nerve function after operation, the limb muscle strength was improved compared with that before operation, and the Karnofsky performance scale (KPS) score reached 100 points 3 months after operation. During the follow-up, 1 patient's tumor recurred after 1 year and received Gamma Knife treatment, and the rest of the patients had no recurrence during the follow-up period.

CONCLUSION

Surgical treatment is the first choice for large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading. It is a safe and effective surgical method to take individualized surgical plan after detailed preoperative assessment of cerebral edema, tumor blood supply, venous sinus compression, and scalp invasion.

[Surgical treatment of large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading]

OBJECTIVE

To investigate the surgical strategy for large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading.

METHODS

The clinical data of 16 patients with large and giant recurrent meningioma in the middle and posterior third part of the superior sagittal sinus with extracranial invasion who underwent surgery in the Department of Neurosurgery of Peking University Third Hospital from May 2019 to May 2022 were retrospectively analyzed. All the patients underwent brain-enhanced magnetic resonance imaging (MRI), magnetic resonance venography (MRV), computed tomography angiography (CTA) and three-dimensional skull computed tomography (CT) before, to evaluate the extent of tumor invasion, the edema of brain tissue, the degree of skull damage, the blood supply of the tumor, and the degree of compression of the superior sagittal sinus, etc, and to formulate an individualized surgical plan. The neurological function of the patients was evaluated 1 week, 1 month, and 3 months after the operation, and the tumor condition was evaluated by brain-enhanced MRI 3 months, 6 months, and 1 year after the operation.

RESULTS

The tumors in the 16 patients were all located in the middle and posterior 1/3 part of the superior sagittal sinus and invaded extracranially. Among them, 8 cases were operated for the second time, 6 cases for the third time, and 2 cases for the fourth time; In the last operation, the bone flap was used to repair the skull in 4 cases, and the titanium mesh was used in 12 cases; Tumor arterials of 3 cases were embolized under digital subtraction angiography (DSA). Tumors of 10 cases were resected at Simpson grade Ⅰ, and 6 cases at Simpson grade Ⅱ; 2 cases underwent decompressive craniectomy during operation, and 14 cases underwent cranioplasty at the same time; scalp incisions of 14 cases were directly sutured, and flap transposition was used in 14 cases. When evaluating nerve function after operation, the limb muscle strength was improved compared with that before operation, and the Karnofsky performance scale (KPS) score reached 100 points 3 months after operation. During the follow-up, 1 patient's tumor recurred after 1 year and received Gamma Knife treatment, and the rest of the patients had no recurrence during the follow-up period.

CONCLUSION

Surgical treatment is the first choice for large and giant recurrent meningiomas near the middle and posterior third part of the superior sagittal sinus with extracranial invading. It is a safe and effective surgical method to take individualized surgical plan after detailed preoperative assessment of cerebral edema, tumor blood supply, venous sinus compression, and scalp invasion.