NewsEtc., April, 1998. Steven Jacques, Oregon Medical Laser Center
The 3rd biennial Optical Society of America (OSA) Topical Meeting on biomedical optics was held in Orlando, FL, March 8-11, 1998. Here is a quick summary of the meeting and some highlights.
There were three meetings held with some simultaneous sessions and some joint sessions. The links to the original OSA website listing the conference schedule of talks with 25-word abstracts are:
This summary lists the session topics and mentions a few talks, but cannot cite all the excellent presentations. My apologies. It was a really good conference.
The session topics were:
My favorite talk was by Britton Chance who discussed the use of a dual criteria for identifying malignant tumors of the breast. He used a source/detector array incorporating two wavelengths to map blood content and hemoglobin oxygenation. The dual criteria for identifying malignant tumors were: (1) an area of increased blood perfusion, AND (2) an area of increased deoxygenation of hemoglobin. The concept is that a malignant tumor will have recruited an enhanced blood supply and that the high metabolic rate of a malignant tumor will more vigorously deplete the oxygenation status of blood in that supply. Dr. Chance reported good performance of this dual criteria in discriminating malignant breast tumors from various benign lesions.
A session of "Light and sound" highlighted projects combining light and sound in optical diagnostics. The two major categories of measurements were:
The session topics were:
My favorite talk was by Michael Feld, M.I.T., who spoke on "Spectral pathology using reflected light." He discussed the work of his colleagues Lev Perelman et al. who are using simple white light reflectance spectroscopy to detect the onset of Barrett's esophagus, a condition which can result from chronic gastric acid reflux and may be regarded as a premalignant condition. The MIT group is delivering/collecting white light using two small closely spaced optical fibers such that the reflectance is dominated by the scattering near the fibers and is somewhat sensitive to the wavelength-dependent Mie scattering from the nuclei. Such Mie scattering causes slight but distinguishable oscillatory variations in the reflectance as a function of wavelength which are characteristic of nuclei size. In Barrett's esophagus, the nuclei of esophageal cells are enlarged from their normal approx. 7 um diameter to greater than 10 um diameter and with a broader range of diameters as well. The MIT group could spectrally detect these differences.
The Mie scattering patterns observed by the MIT group supports the contention long championed by Irv Bigio and his colleagues at Los Alamos National Labs that Mie scattering patterns can detect cancer, although the Los Alamos group's work has emphasized shorter wavelength reflectance changes attributable to smaller scale structures than the nuclei. The Los Alamos group presented their recent work on scattering from cancer cell suspensions, Judith Mourant et al., "Scattering properties of biological cells", in which the wavelength dependence of the reduced scattering coefficient (mus') can be characterized by a value x which is related to the size distribution of scatterers in the cell suspension, mus' = constant*nm^(-x), where nm is the wavelength in the UV-VIS-NIR spectral range.
The session topics were:
This meeting was new at the OSA Spring Topical Meeting, expanding beyond purely optical techniques to consider the physics and chemistry of how lasers and light interact with tissue. Of particular interest were the invited talks by Tayyaba Hasan, Wellman Laboratory of Photomedicine, on "Photodynamic Therapy: current status and future directions", Raimund Hibst, Institut fuer Lasertechnologien in der medizin and Mestechnik, Ulm, Germany, on "Hard tissue laser ablation for caries removal", and Dr. Cornelius Borst, Utrecht Univ. Hospital, The Netherlands, on "The octopus tissue stabilizer for local cardiac wall immobilization during CABG without CPB", illustrating the wide range of topics covered in this meeting.
In summary, the conference was very good. Next year, this biomedical optics community will meet at the SPIE meeting in San Jose, CA, January, 1999. The next OSA Spring Topical Meeting will be held in March, 2000.