A look inside the body: On the trail of cancer
Around 19.3 million people worldwide are diagnosed with cancer every year1. The sooner a tumor can be detected and treated, the better the chances of recovery for affected patients. There is a great need in tumor surgery for new technologies that are able to precisely locate tumors in order to remove them as completely as possible, and that enable a reliable tumor typing and classification to quickly initiate an individual and customized therapy plan for a patient.
Leibniz IPHT is working on various endospectroscopic solutions to address these medical problems, which have been insufficiently addressed so far: A multimodal imaging endoscope concept offers the potential to distinguish tumorous from healthy tissue directly during a surgery by generating spatially high-resolution tissue images containing both morphological and biochemical information. To further characterize tumors in terms of tumor grading and staging, the invaScope – a Raman-based system – was developed to enable physicians to characterize conspicuous tumor tissue histopathologically with pinpoint accuracy, without markers and without taking a biopsy.
Characterize bladder cancer in-vivo using optical biopsy
Bladder cancer ranks tenth among the most frequently diagnosed carcinomas worldwide. Men suffer more often from this type of cancer than women. In 2020, 212,536 people with bladder cancer – almost 40 percent of those affected – died of the disease2. Bladder cancer ranks 13th in the death statistics, alongside lung cancer, cancer of the digestive tract and breast cancer. Improved diagnosis significantly increases the chances of a cure.
Until a clear diagnosis of bladder cancer can be made, it usually takes a few days up to several weeks, during which persons affected live in uncertainty. If cancer is suspected, doctors take a tissue sample from the urinary bladder to differentiate a harmless tissue change from a malignant carcinoma. The sample is then analyzed under the microscope in a histopathological examination. If the diagnosis is "cancer," further operations and accompanying therapeutic measures follow.
However, the histopathological examination only provides information on morphological tissue characteristics, such as structure and shape of the extracted cells. Important biochemical information is not covered. A molecular fingerprint of affected cells would allow a more precise diagnostic characterization of the tumor and help to better predict the course of the disease.
In the picture:
The endomicroscope is designed to precisely assist physicians in the removal of tumors.
In order to improve bladder cancer diagnostics and at the same time shorten the time of uncertainty for persons affected, the EU project "MIB" (Multimodal, endoscopic biophotonic imaging of bladder cancer for point-of-care diagnosis) was launched in 2016.
Together with ten European partner institutions, Leibniz PHT took on the task of developing a compact imaging endoscopic system for the detection of bladder cancer as part of the project. "The invaScope is intended to effectively support physicians in the characterization of bladder tissue. Tumor diagnosis will be possible in a quick and painless manner directly in the urinary bladder and in real time. Findings will be available within a very short time, and health risks for patients will be significantly reduced. Medical interventions, such as cystoscopies, can be associated with complications for those affected, for example with bleeding, bladder perforations or infections," explains Prof. Dr. Iwan Schie, head of the Working Group Multimodal Instrumentation in the Department Spectroscopy / Imaging at Leibniz IPHT.
A special challenge on the way to this system was the development of an endoscopic fiber probe suitable for clinical use. The aim was to make the fiber probe extremely thin, flexible, and robust to enable uncomplicated access to the bladder via the urethra. It was particularly important to ensure that no surrounding tissue would be injured, the examination would involved minimal risks and would be painless for patients. Moreover, the probe also had to be biocompatible and sterilizable. Thanks to the close cooperation with physicians from the Hovedstaden region in Denmark and the medical technology manufacturers Blazejewski MEDI-TECH GmbH and 2M Engineering, the application-related and regulatory requirements could be considered even during the research.
"The European Medical Device Regulation (MDR) imposes very high requirements in terms of documentation, functionality and safety on devices for clinical-investigative research. For us at Leibniz IPHT, the development of the invaScope is the first realization of a system for in-vivo use on humans – much in line with the motto 'From Ideas to Instruments'," explains Iwan Schie.
In the picture:
Compact and flexible: The invaScope, wich Iwan Shie (right) developed together with his team, combines all the necessary components for the diagnosis of bladder cancer in a compact design.
In ex-vivo studies, the researchers first demonstrated on biopsies that Raman spectroscopy, in particular, is suitable for diagnosis of bladder cancer and tumor grade differentiation. It enables label-free biochemical characterization of tissue samples. With an accuracy of 92 percent, it was possible to distinguish healthy from tumorous tissue. In differentiating between highly malignant and less malignant tissue, the accuracy was 84 percent.
The diagnostic performance is improved by combining different optical methods. "In collaboration with the Medical University of Vienna, we were able to show that different optical methods can be well combined and complement each other in diagnosis. The combination of optical coherence tomography, or OCT, and Raman spectroscopy offers the advantage of being able to obtain both depthresolved structural and molecular information from samples. Doctors thus obtain comprehensive and meaningful diagnostic information about the aggressiveness and stage of a bladder carcinoma," continues Iwan Schie.
In 2021, the work on the endoscopic system with fiberoptic Raman probe was completed. The developed probe can be sterilized several times and is therefore reusable. All elements necessary for Raman spectroscopy, such as laser, spectrometer, and camera, are integrated in a compact and splashproof housing, and are supplemented by software specially developed for clinical use. The Raman system is installed on a medical equipment cart and can be used flexibly in operating rooms or outpatient clinics.
In the picture:
Endoscopic, fiber-optic Raman probe that helps distinguish healthy and diseased tissue.
At the Copenhagen Herlev Hospital in Denmark, the invaScope system was subjected to a practical test at the end of 2021 as part of a clinical study. Using the new instrument, physicians were able to examine the bladder wall of 20 study participants within a few minutes each using Raman spectroscopy. For this purpose, the probe was inserted into the bladder through the working channel of a nephroscope, the probe tip was brought into contact with the bladder wall, and the measurements were started. A brightfield camera connected to the system provided simultaneous images from inside the body and assisted in the selection of the tissue region.
"It was fascinating to see the results of our work from the past few years live in the clinical setting. The Danish physicians were convinced by the ease of use of the system and are interested in continuing the development towards a medical product," Iwan Schie summarizes. In addition to medical benefits, the invaScope could offer economic benefits: Expensive and timeconsuming operations involving surgeons, anesthetists and nurses could be better planned due to improved diagnostics, and could be performed in a more targeted manner. This could save costs in the healthcare system.
The endoscopic approach and the uncomplicated operation of the system will make other hard-to-reach regions of the body accessible for application. In a subsequent clinical study, the suitability of the system for the diagnosis of cancer tumors in the neck and head region will be demonstrated.
Tumor margin detection with triple imaging
Researchers at Leibniz IPHT, together with the company Grintech from Jena, have researched and developed a multimodal endoscope for improved tumor margin detection.
So far, surgeons have had to rely on the findings of frozen section diagnostics to be able to see whether a tumor has been completely removed during surgery. The evaluation of the results requires many years of experience and can sometimes be incorrect. Only a subsequent intensive pathological examination of the removed tissue provides certainty. It can take up to four weeks for an exact finding to be available. For patients, this is a time of agonizing uncertainty – during which any remaining tumor cells may already be multiplying again.
Scientists at Leibniz IPHT have researched a diagnostic method that could revolutionize the previous procedure: The endomicroscope is able to reliably distinguish healthy from tumorous tissue in real time in-vivo during a surgery. For this purpose, the system combines powerful laser, innovative optical fiber, and endomicroscopic lens. "In the previous project 'MediCARS', we researched a method for multimodal tissue diagnostics. We have now transferred the experience gained here into a miniaturized flexible endoscope design. Together with our partner, the Grintech GmbH, this has resulted in one of the most compact and powerful endoscopes for gentle in-vivo imaging – an even smaller realization is hardly possible," explains Dr. Tobias Meyer-Zedler, head of the Molecular Imaging Group in the Spectroscopy / Imaging Department at Leibniz IPHT.
To be able to generate as much information as possible from
the tissue to be examined, the researchers combined three imaging techniques: coherent anti-stokes Raman scattering, frequency doubling, and two-photon excited fluorescence microscopy. This multimodal approach visualizes tissue structures and their molecular composition as well as morphology down to the submicrometer scale without labeling. "The generated images can even compete with those of high-resolution, high-end microscopes," summarizes the researcher.
An important milestone in this development was the realization of the double-core double-clad optical fiber, which was designed for both laser guidance and signal acquisition. With expertise from several decades of experience, the fiber experts at Leibniz IPHT developed a microstructured fiber consisting of two cores for guiding the two excitation lasers for coherent anti-stokes Raman scattering, which are used to irradiate the tissue from both cores with light. The two cores are surrounded by an outer cladding that collects the tissue's response to excitation by laser light.
"In order to make the concept fit for clinical application, further challenges lie ahead: We will, for example, further refine the endoscope technologically and perform clinical tests. The approval as a medical device will be another important milestone. In a few years, our endoscope could contribute to optimally support cancer diagnostics in a minimally invasive manner," says Tobias Meyer-Zedler.
1 Cf. Statista: Number of new cancer cases worldwide by cancer type in 2020, 2022: https://de.statista.com/statistik/daten/ studie/286545/umfrage/zahl-der-krebsneuer- krankungen-weltweit/ [17.01.2022]
2 Cf. Statista: Number of cancer deaths by cancer type worldwide 2020, 2022: https:// de.statista.com/statistik/daten/stud- ie/286584/umfrage/zahl-der-krebstodesfa- elle-nach-krebsart-weltweit/ [18.01.2022]