Intelligent Operating Theater Using Intraoperative Open-MRI

Information-guided Surgery Centered on Intraoperative Magnetic Resonance Imaging Guarantees Surgical Safety with Low Mortality

Neurosurgery is complex surgery that requires a strategy that maximizes the removal of tumors and minimizes complications; thus, a safe environment during surgery should be guaranteed. In this study, we aimed to verify the safety of brain surgery using intraoperative magnetic resonance imaging (iMRI), based on surgical experience since 2000. Thus, we retrospectively examined 2,018 surgical procedures that utilized iMRI performed in the operating room at Tokyo Women's Medical University Hospital between March 2000 and October 2019. As per our data, glioma constituted the majority of the cases (1,711 cases, 84.8%), followed by cavernous hemangioma (61 cases, 3.0%), metastatic brain tumor (37 cases, 1.8%), and meningioma (31 cases, 1.5%). In total, 1,704 patients who underwent glioma removal were analyzed for mortality within 30 days of surgery and for reoperation rates and the underlying causes within 24 hours and 30 days of surgery. As per our analysis, only one death out of all the glioma cases (0.06%) was reported within the 30-day period. Meanwhile, reoperation within 30 days was performed in 37 patients (2.2%) due to postoperative bleeding in 17 patients (1.0%), infection in 12 patients (0.7%), hydrocephalus in 6 patients (0.4%), cerebrospinal fluid (CSF) leakage in 1 patient, and brain edema in 1 patient (0.06%). Of these, 14 cases (0.8%) of reoperation were performed within 24 hours, that is, 13 cases (0.8%) due to postoperative bleeding and 1 case (0.06%) due to acute hydrocephalus. Mortality rate within 30 days was less than 0.1%. Thus, information-guided surgery with iMRI can improve the safety of surgical resections, including those of gliomas.

GATOR: connecting integrated operating room solutions based on the IEEE 11073 SDC and ORiN standards

PURPOSE

Medical device interoperability in operating rooms (OR) provides advantages for both, patients and physicians. Several approaches were made to provide standards for successful device integration. However, with high heterogeneity of standards in the market, device vendors may reject these approaches. The aim of this work is therefore to provide a proof of concept for the connection of two promising integration solutions OR.NET and SCOT to increase vendor interest.

METHODS

The connection of devices between both domains is targeted by implementing an application to map device capabilities between the IEEE 11073 SDC and ORiN standards. Potential properties of the respective architectures are defined. The connection was evaluated by latency measurements in a demonstrator setup utilizing an OR light as an exemplary device.

RESULTS

The latency measurements resulted in a similar transmission speed of the GATOR (53.0 ms) and direct SDC-to-SDC (38.0 ms) communication. Direct proprietary ORiN-to-ORiN communication was faster in any case (8.0 ms).

CONCLUSION

A connection between both standards was successfully achieved via the GATOR application. The results show comparable magnitudes of the communication between the standards compared to the direct standard-internal communication.

Quantitative Evaluation of Efficacy of Intraoperative Examination Monitor for Awake Surgery

BACKGROUND

When brain tumors are located near the language area, a test to assess language function is required. During the test, it is practical to display combined information obtained from all the equipment so that the surgeon can confirm the patient's response to the tasks. We developed the intraoperative examination monitor for awake surgery (IEMAS) mainly to combine all information so that the language function test could be performed efficiently. The IEMAS has proved to be useful in clinical settings; however, no quantitative evaluation has been performed. This study aimed to demonstrate the clinical usefulness of the IEMAS through comparison of cases with and without IEMAS use in language function test simulation.

METHODS

The language function test simulator was created to eliminate any uncertain factors, such as symptoms, which vary among patients. Neurosurgeons participated in the test, and the usefulness of the IEMAS was investigated. We analyzed test duration and number of information exchanges between surgeon and examiner.

RESULTS

Total test duration with IEMAS use was significantly shorter than without IEMAS use (116.1 ± 23.1 seconds vs. 147.8 ± 48.7 seconds; P < 0.02). The number of information exchanges between surgeon and examiner was significantly lower with IEMAS use than without IEMAS use (0.2 ± 0.6 times vs. 16.1 ± 15.6 times; P < 0.02).

CONCLUSIONS

We compared cases with and without IEMAS use. Total test duration decreased with IEMAS use, and number of information exchanges was reduced, thus demonstrating the usefulness of the IEMAS.

Development concepts of a Smart Cyber Operating Theater (SCOT) using ORiN technology

Currently, networking has not progressed in the treatment room. Almost every medical device in the treatment room operates as a stand-alone device. In this project, we aim to develop a networked operating room called “Smart Cyber Operating Theater (SCOT)”. Medical devices are connected using Open Resource interface for the Network (ORiN) technology. In this paper, we describe the concept of the SCOT project. SCOT is integrated using the communication interface ORiN, which was originally developed for industry. One feature of ORiN is that the system can be constructed flexibly. ORiN creates abstracts of the same type of devices and increases the robustness of the system for device exchange. By using ORiN technology, we are developing new applications, such as decision-making navigation or a precision guided treatment system.

A Micro Saddle Coil with Switchable Sensitivity for Local High-Resolution Imaging of Luminal Tissue

This paper reports on a micro saddle coil for local high-resolution magnetic resonance imaging (MRI) fabricated by embedding a flexible coil pattern into a polydimethyilsiloxane (PDMS) tube. We can change the sensitivity of the micro coil by deforming the shape of the coil from a saddle-shaped mode to a planar-shaped mode. The inductance, the resistance, and the Q-factor of the coil in the saddle-shaped mode were 2.45 μH, 3.31 Ω, and 39.9, respectively. Those of the planar-shaped mode were 3.07 μH, 3.92 Ω, and 42.9, respectively. In MRI acquired in saddle-shaped mode, a large visible area existed around the coil. Although the sensitive area was considerably reduced in the planar-shaped mode, clear MRI images were obtained. The signal-to-noise ratios (SNR) of the saddle-shaped and planar-shaped modes were 194.9 and 505.9, respectively, at voxel size of 2.0 × 2.0 × 2.0 mm³ and 11.7 and 37.4, respectively, at voxel size of 0.5 × 0.5 × 1.0 mm³. The sensitivity of the saddle-shaped and the planar-shaped modes were about 3 times and 10 times higher, respectively, than those of the medical head coil at both voxel sizes. Thus, the micro saddle coil enabled large-area imaging and highly sensitive imaging by switching the shape of the coil.

Correlation between surgical manipulations and the variation of surgeon's heart rate in brain surgery: technical note

For improvement of surgical performance and safety, we record surgeries by video cameras. However, analysis of the video records is time consuming. To help this task, we are developing methods to automatically mark up significant time points in the surgery. As a possible mean for the marking, we focused on the surgeon's heart rate. During a craniotomy of an intracranial glioma, we recorded the surgeon's electrocardiogram using a telemeter and measured the R-to-R interval (RRI). We detected the stable state of heart rate as a peak-to-peak RRI of less than 5% of the mean of RRI data from 15 consecutive heartbeats. We also quantified the frequency of brain touches by the surgeon under the surgical microscope. We examined the association between the stability of surgeon's heart rate and the brain touches using a chi-square test. As the result, the stable state of surgeon's heart rate was associated with the brain touches (p < 0.05, odds ratio 5.1). We edited a one-minute digest video of the surgery based on only the heart rate data, and it was sufficient to understand how the surgery was preceded.

Development of a new compact intraoperative magnetic resonance imaging system: concept and initial experience

BACKGROUND

Magnetic resonance imaging (MRI) during surgery has been shown to improve surgical outcomes, but the current intraoperative MRI systems are too large to install in standard operating suites. Although 1 compact system is available, its imaging quality is not ideal.

OBJECTIVE

We developed a new compact intraoperative MRI system and evaluated its use for safety and efficacy.

METHODS

This new system has a magnetic gantry: a permanent magnet of 0.23 T and an interpolar distance of 32 cm. The gantry system weighs 2.8 tons and the 5-G line is within the circle of 2.6 m. We created a new field-of-view head coil and a canopy-style radiofrequency shield for this system. A clinical trial was initiated, and the system has been used in 44 patients.

RESULTS

This system is significantly smaller than previous intraoperative MRI systems. High-quality T2 images could discriminate tumor from normal brain tissue and identify anatomic landmarks for accurate surgery. The average imaging time was 45.5 minutes, and no clinical complications or MRI system failures occurred. Floating organisms or particles were minimal (1/200 L maximum).

CONCLUSION

This intraoperative, compact, low-magnetic-field MRI system can be installed in standard operating suites to provide relatively high-quality images without sacrificing safety. We believe that such a system facilitates the introduction of the intraoperative MRI.

Wireless modification of the intraoperative examination monitor for awake surgery

The dedicated intraoperative examination monitor for awake surgery (IEMAS) was originally developed by us to facilitate the process of brain mapping during awake craniotomy and successfully used in 186 neurosurgical procedures. This information-sharing device provides the opportunity for all members of the surgical team to visualize a wide spectrum of the integrated intraoperative information related to the condition of the patient, nuances of the surgical procedure, and details of the cortical mapping, practically without interruption of the surgical manipulations. The wide set of both anatomical and functional parameters, such as view of the patient's mimic and face movements while answering the specific questions, type of the examination test, position of the surgical instruments, parameters of the bispectral index monitor, and general view of the surgical field through the operating microscope, is presented compactly in one screen with several displays. However, the initially designed IEMAS system was occasionally affected by interruption or detachment of the connecting cables, which sometimes interfered with its effective clinical use. Therefore, a new modification of the device was developed. The specific feature is installation of wireless information transmitting technology using audio-visual transmitters and receivers for transfer of images and verbal information. The modified IEMAS system is very convenient to use in the narrow space of the operating room.

Development of modified intraoperative examination monitor for awake surgery (IEMAS) system for awake craniotomy during brain tumor resection

Gliomas represent the most frequent type of primary intracranial tumors, which originate from the brain tissue itself, have infiltrative growth, unclear borders, and usually affect functionally-important cerebral structures. From March 2000 till March 2010, 839 neurosurgical procedures directed on resection of such neoplasms were performed in the intelligent operating theater of Tokyo Women's Medical University with the use of intraoperative MRI, real-time updated neuronavigation system, and Hi-vision operative microscope. To facilitate maximal possible tumor resection with minimal risk of neurological morbidity a special device, called Intraoperative Examination Monitor for Awake Surgery (IEMAS) was developed by us. It provides an opportunity to visualize a wide spectrum of inraoperative information related to condition of the patient, nuances of the surgical procedure, and details of the cortical mapping. The wide set of both anatomical and functional parameters, such as view of the patient's mimic and face movements during answering on the specific questions, type of examination test, position of the surgical instruments, parameters of the bispectral index monitor, and general view of the surgical field through the operating microscope and/or endoscope, is presented compactly in one screen with several displays, which allows fast integrated real-time analysis of the multiple data, nearly without interruption of the surgical manipulations. All members of the surgical team can share this information using several in-room liquid crystal displays. However, the initially designed IEMAS system was occasionally affected by interruption or detachment of the connecting cables, which could interfere with effective advancement of the surgical procedure. To avoid this problem a modified device was created. Its specific feature is wireless information transmitting function attained by incorporation of transmitters with a frequency range of 2.4 GHz. The clinical testing of t- - his system was initiated on February 1, 2010, but quickly revealed crossed line effect between transmitters and receivers. To overcome this obstacle and to isolate transmitters, one channel was changed from wireless connection into wired, which resulted in significant improvement of the clearness of both transmitted images and sounds, and provides an opportunity for effective clinical use of the device. In perspective we wish to make IEMAS system fully wireless, using several types of frequency range transmitters.

Real-time magnetic resonance-guided microwave coagulation therapy for pelvic recurrence of rectal cancer: initial clinical experience using a 0.5 T open magnetic resonance system

PURPOSE

This study aims to evaluate consecutive cases of recurrent rectal cancer in the pelvic cavity treated with microwave coagulation therapy using real-time navigation by an open magnetic resonance system.

METHODS

Nine recurrent pelvic lesions in 8 patients after curative resection of rectal cancer were treated with real-time magnetic resonance-guided microwave coagulation therapy as a palliative local therapy to reduce tumor volume and/or local pain. Clinical and pathological data were collected retrospectively by reviewing medical records and clinical imaging results.

RESULTS

Seven patients received other treatments before real-time magnetic resonance-guided microwave coagulation. Six patients had distant synchronous metastases. Three patients underwent surgery under lumbar anesthesia. Microwave coagulation was performed percutaneously in 5 lesions and under laparotomy in 4 lesions. Although adverse events related to microwave coagulation (skin necrosis and nerve injury) were observed, no fatal complications occurred. Local re-recurrence was observed in 2 of 9 ablated lesions. Except for 1 patient who died of chronic renal failure, the remaining 7 patients died of cancer. Median overall survival after microwave coagulation for all patients was 10 months (range, 4-37 mo). Median overall survival after discovery of pelvic recurrence in all patients was 22 months (range, 9-42 mo).

CONCLUSIONS

The benefits of using an open magnetic resonance system in the pelvic cavity include the abilities to treat tumors that cannot be visualized by other modalities, to demonstrate internal architectural changes during treatment, to differentiate treated vs untreated areas, and to allow adjustments to the treatment plan during the procedure. Additional studies are required to clarify the efficacy of tumor coagulation for local control.

Shift of the pyramidal tract during resection of the intraaxial brain tumors estimated by intraoperative diffusion-weighted imaging

The present study evaluated the shift of the pyramidal tract during resection of 17 proximal intraaxial brain tumors. In each case intraoperative diffusion-weighted (iDW) magnetic resonance imaging with a motion-probing gradient applied in the anteroposterior direction was performed using a scanner with a 0.3 T vertical magnetic field. The position of the white matter bundles containing the pyramidal tract was estimated on the coronal images before and after resection of the neoplasm, and both quantitative and directional evaluation of its displacement was done. In all cases iDW imaging provided visualization of the structure of interest. The magnitude of the pyramidal tract displacement due to removal of the neoplasm varied from 0.5 to 8.7 mm (mean 4.4 +/- 2.5 mm) on the lesion side and from 0 to 3.6 mm (mean 1.3 +/- 1.1 mm) on the normal side (p < 0.001). Tumor location in regards to the pyramidal tract was significantly associated with the direction of the pyramidal tract displacement (p < 0.05). Outward shift occurred in 10 out of 13 cases of the lateral neoplasms, whereas in all 4 superomedial tumors inward shift was marked. In conclusion, the direction of the pyramidal tract displacement during resection of the proximal intraaxial brain tumors is mainly determined by position of the neoplasm, but can be unpredictable in some cases, which necessitates use of subcortical brain mapping and intraoperative imaging, particularly iDW imaging with updated neuronavigation.

Towards oncological application of Raman spectroscopy

As the possibilities in the treatment of cancer continue to evolve, its early detection and correct diagnosis are becoming increasingly important. From the early detection of cancer to the guidance of oncosurgical procedures new sensitive in vivo diagnostic tools are much needed. Many studies report the Raman spectroscopic detection of malignant and premalignant tissues in different sites of the body with high sensitivities. The great appeal of this technique lies in its potential for in vivo clinical implementation. We present an overview of the in vitro and in vivo work on the oncological application of Raman spectroscopy and discuss its potential as a new tool in the clinico-oncological practice. Opportunities for integration of Raman spectroscopy in oncological cure and care as a real-time guidance tool during diagnostic (i.e. biopsy) and therapeutic (surgical resection) modalities as well as technical shortcomings are discussed from a clinician's point of view.

Comparison of navigated 3D ultrasound findings with histopathology in subsequent phases of glioblastoma resection

OBJECTIVE

The purpose of the study was to compare the ability of navigated 3D ultrasound to distinguish tumour and normal brain tissue at the tumour border zone in subsequent phases of resection.

MATERIALS AND METHODS

Biopsies were sampled in the tumour border zone as seen in the US images before and during surgery. After resection, biopsies were sampled in the resection cavity wall. Histopathology was compared with the surgeon's image findings.

RESULTS

Before resection, the tumour border was delineated by ultrasound with high specificity and sensitivity (both 95%). During resection, ultrasound had acceptable sensitivity (87%), but poor specificity (42%), due to biopsies falsely classified as tumour by the surgeon. After resection, sensitivity was poor (26%), due to tumour or infiltrated tissue in several biopsies deemed normal by ultrasound, but the specificity was acceptable (88%).

CONCLUSIONS

Our study shows that although glioblastomas are well delineated prior to resection, there seem to be overestimation of tumour tissue during resection. After resection tumour remnants and infiltrated brain tissue in the resection cavity wall may be undetected. We believe that the benefits of intraoperative ultrasound outweigh the shortcomings, but users of intraoperative ultrasound should keep the limitations shown in our study in mind.

Raman spectroscopic characterization of porcine brain tissue using a single fiber-optic probe

Accurate targeting of diseased and healthy tissue has significantly been improved by MRI/CT-based navigation systems. Recently, intraoperative MRI navigation systems have proven to be powerful tools for the guidance of the neurosurgical operations. However, the widespread use of such systems is held back by the costs, the time consumption during operation, and the need for MR-compatible surgical devices. Raman spectroscopy is a nondestructive optical technique that enables real-time tissue identification and classification and has proved to be a powerful diagnostic tool in a large number of studies. In the present report, we have investigated the possibility of distinguishing different brain structures by using a single fiber-optic probe to collect Raman scattered light in the high-wavenumber region of the spectrum. For the Raman measurements, 7 pig brains were sliced in the coronal plain and Raman spectra were obtained of 11-19 anatomical structures. Adjacent brain structures could be distinguished based on their Raman spectra, reflecting the differences in their biochemical composition and illustrating the potential Raman spectroscopy holds as a guidance tool during neurosurgical procedures.