Biomedical Imaging
The main objective of this group is multidisciplinary research collaborations across a wide range of disciplines to develop non-invasive, in vivo three-dimensional (sub)- cellular resolution, molecular and functional imaging technology that is of significant diagnostic value in ophthalmology as well as cancer diagnosis in a variety of medical fields.
In particular the aims of this research group is the development of compact, low cost, ultrabroad bandwidth light sources, optical as well as hardware and software engineering for the development and clinical application of novel in vivo ultrahigh resolution and functional optical coherence tomography (OCT) technology. OCT is an emerging non-invasive, optical medical diagnostic imaging modality which enables in vivo cross-sectional tomographic visualization of internal microstructure in biological systems, achieving unprecedented image resolutions (1-3 µm), approximately 100 times better than that of conventional ultrasound. Therefore OCT enables for example unprecedented visualization of intraretinal layers and has the potential to perform non-invasive optical biopsy of the human retina, i.e. visualization of intraretinal morphology approaching the level of that achieved with histopathology.
Histology (left) and ultrahigh resolution OCT (right) of a primate retina (Macaca fascicularis).
gc ax: ganglion cell axon layer, gc: ganglion cells, ipl: inner plexiform layer, inl: inner nuclear layer, H’s f: fibers of Henle, onl: outer nuclear layer, cis/cos: cone inner/outer segments, pe: pigment epithelial layer, ch cap: choriocapillaris, ch: choroid,
(Collaboration with P. Ahnelt, Department of Physiology, Medical University Vienna and A. Cowey, Oxford University)
Click on the thumbnail below to see the full image:
45.1 Kb
Click the link below to download the video:
Three dimensional ultrahigh resolution OCT – optical biopsy of the retina
The development of novel detection techniques (Frequency Domain OCT) enabled the combination of ultrahigh resolution OCT (UHR OCT) and extremely fast data acquisition for three dimensional UHR OCT of the living human retina with high axial resolution of 3 µm at video-rate with up to 25-50 B-scans/second. Employing other wavelengths for better penetration into the choroid are investigated.
In vivo three dimensional ultrahigh resolution OCT of a normal human retina at different views (A,B) with simultaneous fly through B-scans of the whole volume (upper left corner). Virutal C-scans system (C-F) enables arbitrary horizontal removal of different retinal layers revealing morphologic information inside the scanned volume. (3D rendering developed in collaboration with C. Glittenberg, S. Binder, Ludwig Boltzmann Institute, Vienna, Austria)
Click on the thumbnail below to see the full image:
78.8 Kb
Click the link below to download the video:
In vivo three dimensional ultrahigh resolution OCT of a patient with macular hole (A) with simultaneous fly through B-scans of the whole volume (upper left corner). A virtual biopsy system allows the user to excise any given shape from the probe in order to visualize intraretinal morphology inside the acquired volume (B-F).
Click on the thumbnail below to see the full image:
72.0 Kb
Click the link below to download the video:
Adaptive optics ultrahigh resolution OCT- cellular resolution retinal imaging
Using adaptive optics to correct higher order aberrations of the human eye in combination with high speed, three-dimensional ultrahigh resolution OCT enables unprecedented in vivo volumetric visualization of intraretinal cellular features like photoreceptors.
Functional ultrahigh resolution OCT – depth resolved functional tissue information
In addition, extension of ultrahigh resolution OCT are developed that provide non-invasive depth resolved functional imaging of the retina, including spectroscopic, blood flow or physiologic tissue information. These extensions of OCT should not only improve image contrast, but should also enable the differentiation of retinal pathologies via localized spectroscopic properties or functional state.
Optophysiology – non-invasive optical analogue of electrophysiology
Functional OCT: Doppler Flow OCT (left top: bidirectional flow of artery and vein labelled in red and green);Spectroscopic OCT (left bottom: optical contrasting via melanin concentration in a patient with RPE atrophy);Optophysiology (right: depth resolved detection of retinal physiology via time resolved optical backscattering changes, (Collaboration with R. Pflug, Department of Physiology, Medical University Vienna)
Electrophysiology is the ‘golden standard’ to detect physiologic/functional changes since decades. This method is invasive, time intensive and has no depth resolution and poor transverse resolution. Non-contact, optical probing of retinal response to visual stimulation with <10µm spatial resolution, achieved by using functional ultrahigh resolution optical coherence tomography (fUHROCT) has recently been demonstrated for the first time in vitro in isolated rabbit retinas. The method utilizes the fact that physiological changes in dark-adapted retinas caused by light stimulation can result in local variations of the tissue reflectivity. fUHROCT scans were acquired prior, during and after external white light stimulation and could be correlated to simultaneous ERG measurements. The observed stimulus-related changes in the retinal reflectivity appeared most pronounced in the inner/outer segments of the photoreceptor layer. Control experiments, e.g. dark adaptation versus light stimulation indicate that the origin of the observed optical changes might be the altered physiological state of the retina evoked by the light stimulus.
Click on the thumbnail below to see the full image.
67.9 KbUltrahigh resolution OCT in non-transparent tissue – early cancer diagnosis
The key objective is to develop ultrahigh resolution OCT (UHR OCT) technology which enables non-invasive in vivo optical biopsy for detection of early neoplastic changes at a sub-cellular level for improved cancer diagnosis. This novel version of OCT would enable real time, in situ visualization of tissue microstructure without the need to excisionally remove and process a specimen as in conventional biopsy and histopathology. Preliminary studies to evaluate the clinical feasibility of three-dimensional UHR OCT in dermatology, gastroenterology and neurology are conducted at the moment.
In vivo 3D UHR OCT in dermatology (human skin (left) collaboration H. Pehamberger, Medical University Vienna) and gastroenterology (mouse colon (right) collaboration J. Barton, A. Tumlinson, L. Hariri, University of Arizona, USA)
Click on the thumbnail below to see the full image.
82.6 KbIn the last years, we have initiated and established several academic collaborations:
Photo of Biomedical Imaging Group Members: Wolfgang Drexler, Boris Hermann, Boris Považay, Bernd Hofer, Angelika Unterhuber, Enrique J. Fernández.
- Massachusetts Institute of Technology, Cambridge, USA (Prof. James G. Fujimoto)
- Imperial College (Dr. Sergei Popov, Prof. Roy J. Taylor)
- University of Arizona (Prof. Jennifer Barton, Alex Tumlinson, Lida Hariri)
- LMU Munich, MPQ Garching, Germany (Prof. F. Krausz, Dr. A. Apolonski)
- City University London (Dr. Luis Diaz-Santana, Dr. Steve Grupetta)
- Laboratorio de Optica, Universidad de Murcia, Murcia, Spain (Prof. Pablo Artal)
- RISOE National Laboratory, Denmark (Prof. Peter Anderson, Dr. Lars Thrane)
- Centre for Biomedical Engineering and Physics, Medical University Vienna (Prof. L. Schmetterer)
- Ludwig Boltzmann Institute, Rudolfstiftung Vienna, Austria (Prof. Susanne Binder, Dr. Carl Glittenberg, Dr. Florian Zeiler, Dr. Christiane Falkner)
- Department of Ophthalmology, Medical University Vienna, Austria (Prof. U. Schmid-Erfurth, Prof. O. Findl, Prof. M. Stur, Prof. C. Scholda)
- Department for Physiology, Medical University Vienna (Prof. Peter Ahnelt, Dr. Renate Pflug)
- Institute of Electrical Measurements and Circuit Design, Vienna University of Technology (Dr. H. Arthaber)
- Institut fuer Nachrichtentechnik und Hochfrequenztechnik, Technische Universitaet Wien (Prof. F. Hlawatsch, Prof. G. Matz)
- Department of Dermatology, Medical University Vienna (Prof. H. Pehamberger, Prof. M. Binder)
- Institute of Neurology, Medical University Vienna (Prof. H. Budka, Dr. C. Preusser)
- Department for Histology, Medical University Vienna (Prof. Pavelka)
Since several years, we are also collaborating with following companies:
- Carl Zeiss Meditec AG (Jena, D) und Inc. (Dublin, Ca, USA)
- Femtolasers Produktions GmbH (Vienna, Austria)
- SuperlumDiodes Ltd (Moscow, Russia)
- NP Photonics (Tucson, USA)
- Crystal Fibre (Birkeroed, Denmark)
- Laser Quantum (Cheshire, GB).
- Novartis Ophthalmics AG (Basel, CH)
- Imaging Eyes (Orsay, France)
- Thorlabs Inc. (USA) & GmbH (Germany)
- Hamamatsu Photonics GmbH (Germany) & K.K. (Japan)
We are also working with two external members:
Enrique J. Fernández (Laboratorio de Optica, Universidad de Murcia, Spain)
Harald Sattmann (Centre for Biomedical Engineering and Physics, Medical University Vienna, Austria)