Interstitial imaging with multiple diffusive reflectance spectroscopy projections for in vivo blood vessels detection during brain needle biopsy procedures

Intraoperative ex-vivo epifluorescent diagnostics of stereotactic brain biopsies using EndoScell scanner: diagnostic accuracy study

Brain biopsy is commonly employed for the histological diagnosis of complex intracranial diseases. To improve the positive diagnostic rate, the precision of intraoperative tissue sampling is critical. This study evaluated the accuracy of fluorescence imaging technology in rapidly distinguishing tumours from nontumour tissue during surgery, thus providing real-time feedback to surgeons and optimizing the surgical workflow. Biopsy samples from 65 patients were selected for this study. The lesion tissues were sequentially stained with sodium fluorescein and methylene blue, followed by fluorescence imaging via a handheld EndoScell scanner under an intraoperative cellular microscope. Frozen section examinations and haematoxylin-eosin (HE) staining were performed on the same lesion tissue by the pathology department. The time required for fluorescence imaging and pathology of frozen sections was recorded. The results of fluorescence imaging (whether the tissue was a tumour or nontumour tissue) and frozen pathology (whether the tissue was a tumour or nontumour tissue) were also recorded. The HE staining results were used as the final gold standard for diagnosis. The sensitivity, specificity, area under the curve (AUC), Kappa consistency test, and diagnostic efficiency of both methods were calculated. Lesion tissue and diagnostic results were successfully obtained from all 65 patients. When HE-stained histopathology was used as the gold standard, the sensitivity of fluorescence imaging was 100% (95% CI: 0.917-1.000), and the specificity was 63.6% (95% CI: 0.316-0.876). In comparison, the sensitivity of frozen section pathology was 88.9% (95% CI: 0.767-0.954), and the specificity was 100% (95% CI: 0.679-1.000). Both methods demonstrated high diagnostic accuracy. ROC curve analysis revealed that the AUCs for fluorescence imaging and frozen pathology were 0.818 and 0.944, respectively, with no significant difference observed in diagnostic performance (Z = 1.597, P > 0.05). Kappa consistency tests indicated that the Kappa value for frozen pathology compared with HE staining was 0.730 (P < 0.001); for fluorescence imaging compared with HE staining, the Kappa value was 0.744 (P < 0.001), thus demonstrating strong agreement with the HE staining results for both methods. In terms of time efficiency, fluorescence imaging was significantly faster than frozen section pathology [6 (4, 7) min vs. 48 (46, 55) min, Z=-9.856, P < 0.001], thus showing a clear advantage regarding time efficiency for fluorescence imaging. Intraoperative fluorescence imaging via an EndoScell scanner, which represents a novel method for histopathological diagnosis, has high diagnostic accuracy and efficiency. This method provides real-time guidance for tissue sampling strategies in brain biopsy, thereby improving the positive diagnostic rate and reducing surgical risk.

In situ optical feedback in brain tumor biopsy: A multiparametric analysis

Background

Brain tumor needle biopsy interventions are inflicted with nondiagnostic or biased sampling in up to 25% and hemorrhage, including asymptomatic cases, in up to 60%. To identify diagnostic tissue and sites with increased microcirculation, intraoperative optical techniques have been suggested. The aim of this study was to investigate the clinical implications of in situ optical guidance in frameless navigated tumor biopsies.

Methods

Real-time feedback on protoporphyrin IX (PpIX) fluorescence, microcirculation, and gray-whiteness was given before tissue sampling (272 positions) in 20 patients along 21 trajectories in total. The primary variables of investigation were fluorescence in relation to neuropathological findings and gadolinium (Gd) enhancement, increased cerebral microcirculation in relation to bleeding incidence, number of trajectories, and impact on operation time.

Results

PpIX fluorescence was detected in Glioblastoma IDH-wildtype CNS WHO grade 4 (n = 12), Primary diffuse large B-cell lymphoma (n = 3), astrocytoma IDH-mutated CNS WHO grade 4 (n = 1) (Ki67 indices ≥ 15%). For 2 patients, no PpIX fluorescence or Gd was found, although samples contained tumorous tissue (Ki67 index 6%). Increased microcirculation was found along 9 trajectories (34 sites), located in cortical, tumorous, or tentorium regions. Postoperative bleedings (n = 10, nine asymptomatic) were related to skull opening or tissue sampling. This study strengthens the proposed independence from intraoperative neuropathology as PpIX fluorescence is detected. Objective real-time feedback resulted in fewer trajectories compared to previous studies indicating reduced operation time.

Conclusions

The integrated optical guidance system provides real-time feedback in situ, increasing certainty and precision of diagnostic tissue before sampling during frameless brain tumor biopsies.

One-Insertion Stereotactic Brain Biopsy Using In Vivo Optical Guidance-A Case Study

BACKGROUND

Stereotactic neurosurgical brain biopsies are afflicted with risks of inconclusive results and hemorrhage. Such complications can necessitate repeated trajectories and prolong surgical time.

OBJECTIVE

To develop and introduce a 1-insertion stereotactic biopsy kit with direct intraoperative optical feedback and to evaluate its applicability in 3 clinical cases.

METHODS

An in-house forward-looking probe with optical fibers was designed to fit the outer cannula of a side-cutting biopsy kit. A small aperture was made at the tip of the outer cannula and the edges aligned with the optical probe inside. Stereotactic biopsies were performed using the Leksell Stereotactic System. Optical signals were measured in millimeter steps along the preplanned trajectory during the insertion. At the region with the highest 5-aminolevulinic acid (5-ALA)-induced fluorescence, the probe was replaced by the inner cannula, and tissue samples were taken. The waiting time for pathology diagnosis was noted.

RESULTS

Measurements took 5 to 10 minutes, and the surgeon received direct visual feedback of intraoperative 5-ALA fluorescence, microcirculation, and tissue gray-whiteness. The 5-ALA fluorescence corroborated with the pathological findings which had waiting times of 45, 50, and 75 minutes. Because only 1 trajectory was required and the patient could be prepared for the end of surgery immediately after sampling, this shortened the total surgical time.

CONCLUSION

A 1-insertion stereotactic biopsy procedure with real-time optical guidance has been presented and successfully evaluated in 3 clinical cases. The method can be modified for frameless navigation and thus has great potential to improve safety and diagnostic yield for both frameless and frame-based neurosurgical biopsy procedures.

Noninvasive hemoglobin sensing and imaging: optical tools for disease diagnosis

SIGNIFICANCE

Measurement and imaging of hemoglobin oxygenation are used extensively in the detection and diagnosis of disease; however, the applied instruments vary widely in their depth of imaging, spatiotemporal resolution, sensitivity, accuracy, complexity, physical size, and cost. The wide variation in available instrumentation can make it challenging for end users to select the appropriate tools for their application and to understand the relative limitations of different methods.

AIM

We aim to provide a systematic overview of the field of hemoglobin imaging and sensing.

APPROACH

We reviewed the sensing and imaging methods used to analyze hemoglobin oxygenation, including pulse oximetry, spectral reflectance imaging, diffuse optical imaging, spectroscopic optical coherence tomography, photoacoustic imaging, and diffuse correlation spectroscopy.

RESULTS

We compared and contrasted the ability of different methods to determine hemoglobin biomarkers such as oxygenation while considering factors that influence their practical application.

CONCLUSIONS

We highlight key limitations in the current state-of-the-art and make suggestions for routes to advance the clinical use and interpretation of hemoglobin oxygenation information.

Optical Brain Biopsy with a Fluorescence and Vessel Tracing Probe

BACKGROUND

Accurate stereotactic biopsies of brain tumors are imperative for diagnosis and tailoring of the therapy. Repetitive needle insertions enhance risks of brain lesioning, hemorrhage, and complications due to prolonged procedure.

OBJECTIVE

To investigate clinical benefits of a combined 5-aminolaevulinic acid (5-ALA) fluorescence and laser Doppler flowmetry system for the detection of malignant brain tumor and blood vessels in stereotactic biopsies.

METHODS

Planning of targets and trajectories was followed by optical measurements in 20 patients, using the Leksell Stereotactic System and a manual insertion device. Fluorescence spectra, microvascular blood flow, and tissue grayness were recorded each millimeter along the paths. Biopsies were taken at preplanned positions. The diagnoses were compared with the fluorescence signals. The recordings were plotted against measurement positions and compared. Sites indicating a risk of hemorrhage were counted as well as the time for the procedures.

RESULTS

Signals were recorded along 28 trajectories, and 78 biopsies were collected. The final diagnosis showed 17 glioblastomas, 2 lymphomas, and 1 astrocytoma grade III. Fluorescence was seen along 23 of the paths with 4 having the peak of 5-ALA fluorescence 3 mm or more from the precalculated target. There was increased microcirculation in 40 of 905 measured positions. The measurement time for each trajectory was 5 to 10 min.

CONCLUSION

The probe provided direct feedback of increased blood flow along the trajectory and of malignant tissue in the vicinity of the target. The method can increase the precision and the safety of the biopsy procedure and reduce time.

Multispectral diffuse reflectance can discriminate blood vessels and bleeding during neurosurgery based on low-frequency hemodynamics

SIGNIFICANCE

The practicality of optical methods detecting tissue optical contrast (absorption, elastic and inelastic scattering, fluorescence) for surgical guidance is limited by interferences from blood pooling and the resulting partial or complete inability to interrogate cortex and blood vessels.

AIM

A multispectral diffuse reflectance technique was developed for intraoperative brain imaging of hemodynamic activity to automatically discriminate blood vessels, cortex, and bleeding at the brain surface.

APPROACH

A manual segmentation of blood pooling, cortex, and vessels allowed the identification of a frequency range in hemoglobin concentration variations associated with high optical signal in blood vessels and cortex but not in bleeding. Reflectance spectra were then used to automatically segment areas with and without hemodynamic activity as well as to discriminate blood from cortical areas.

RESULTS

The frequency range associated with low-frequency hemodynamics and respiratory rate (0.03 to 0.3 Hz) exhibits the largest differences in signal amplitudes for bleeding, blood vessels, and cortex. A segmentation technique based on simulated reflectance spectra initially allowed discrimination of blood (bleeding and vessels) from cortical tissue. Then, a threshold applied to the low-frequency components from deoxyhemoglobin allowed the segmentation of bleeding from vessels. A study on the minimum acquisition time needed to discriminate all three components determined that ∼25  s was necessary to detect changes in the low-frequency range. Other frequency ranges such as heartbeat (1 to 1.7 Hz) can be used to reduce the acquisition time to few seconds but would necessitate optimizing instrumentation to ensure larger signal-to-noise ratios are achieved.

CONCLUSIONS

A method based on multispectral reflectance signals and low-frequency hemoglobin concentration changes can be used to distinguish bleeding, blood vessels, and cortex. This could be integrated into fiber optic probes to enhance signal specificity by providing users an indication of whether measurements are corrupted by blood pooling, an important confounding factor in biomedical optics applied to surgery.

Rise of Raman spectroscopy in neurosurgery: a review

SIGNIFICANCE

Although the clinical potential for Raman spectroscopy (RS) has been anticipated for decades, it has only recently been used in neurosurgery. Still, few devices have succeeded in making their way into the operating room. With recent technological advancements, however, vibrational sensing is poised to be a revolutionary tool for neurosurgeons.

AIM

We give a summary of neurosurgical workflows and key translational milestones of RS in clinical use and provide the optics and data science background required to implement such devices.

APPROACH

We performed an extensive review of the literature, with a specific emphasis on research that aims to build Raman systems suited for a neurosurgical setting.

RESULTS

The main translatable interest in Raman sensing rests in its capacity to yield label-free molecular information from tissue intraoperatively. Systems that have proven usable in the clinical setting are ergonomic, have a short integration time, and can acquire high-quality signal even in suboptimal conditions. Moreover, because of the complex microenvironment of brain tissue, data analysis is now recognized as a critical step in achieving high performance Raman-based sensing.

CONCLUSIONS

The next generation of Raman-based devices are making their way into operating rooms and their clinical translation requires close collaboration between physicians, engineers, and data scientists.