May 25, 2012
In brief: research round-up
Microscope visualizes flow of individual blood cells
Researchers from Technion, the Israel Institute of Technology, have invented an optical microscope that provides high-resolution images of individual blood cells as they flow inside the body, simply by shining light through the skin. The device uses spectrally encoded confocal microscopy, which creates images by splitting a light beam into its constituent wavelengths. A probe pressed against the patient's skin directs the line of light across a blood vessel near the surface. Blood cells crossing the spectral line scatter the light, which is collected and analysed to create 2D images of the flowing cells (Biomed. Opt. Express 3 1455).
The team used the microscope to image blood flowing through a vessel in the lower lip of a volunteer, successfully measuring the average diameter of the red and white blood cells and calculating the volume of different cell types, a key measurement for many medical diagnoses. They note that while other blood-scanning systems with cellular resolution do exist, these are less practical, relying on bulky equipment or injection of fluorescent dyes. The researchers are now working on a second-generation system with higher penetration depth, and also plan to miniaturize the (currently shoebox-sized) system.
Guided brachytherapy improves cervical cancer outcome
The use of 3D image-guided adaptive brachytherapy to treat cervical cancer has proven effective at controlling the return and spread of the disease and, in most cases, avoids the need for hysterectomies. That's the conclusion of a study from Institut Gustave Roussy in France, presented by Renaud Mazeron at the recent World Congress of Brachytherapy in Barcelona, Spain. In the study, 163 cervical cancer patients all received concomitant chemoradiation, followed by brachytherapy guided by either MRI (in 88% of cases) or CT.
Of 61 women who underwent a radical hysterectomy, residual cancer cells were found in only 13 cases. After an average follow-up of 36 months, 45 patients had relapsed, 70.4% of whom had distant metastases. After three years, overall and disease-free survival were 84% and 73%, respectively. Only 12 patients experienced more severe side-effects (grade 3/4), but of these, nine had undergone a hysterectomy after radiotherapy. Mazeron noted that results were far superior to historical data, with high rates on control at the primary tumour site.
Photoacoustics promising for breast cancer diagnosis
Preliminary results from tests of a photoacoustic imaging device demonstrate that the technology can distinguish malignant breast tissue by providing high-contrast tumour images. Researchers from the University of Twente and Medisch Spectrum Twente Hospital in the Netherlands used the Twente Photoacoustic Mammoscope (PAM) to visualize breast tumours in 10 patients with malignancies and two with cysts. The PAM device, which is built into a hospital bed, scans the breast with 1064 nm laser light. Increased absorption in malignant tissue increases the temperature slightly, creating a pressure wave that's detected by an ultrasound transducer. Reconstructed images show abnormal areas as high intensity (Opt. Express 20 11582).
By comparing photoacoustic data with conventional imaging data and tissue exams, the team showed that malignancies produced a distinct photoacoustic signal. They also observed that the photoacoustic contrast of the abnormality was higher than the contrast on X-ray mammography. Next, they plan to make technical improvements to the instrument and perform studies on less suspicious lesions to further investigate PAM's potential.
Simple intestinal probe detects pancreatic cancer
A small study performed at Mayo Clinic's campus in Florida has demonstrated that using a light probe to image the small intestine close to its junction with the pancreas can detect pancreatic cancer. The light probe, developed by collaborators at Northwestern University, uses polarization gating spectroscopy to measure the amount of oxygenated blood and the size of blood vessels in tissue. As the pancreas is notoriously difficult to visualize, due to its deep location in the abdomen, the investigators examined "field effects", in which a tumour growing in the pancreas produces changes in cells and blood vessels in the adjoining small intestine.
The researchers tested the probe on 10 patients who had pancreatic cancer and nine participants who did not. Measurements of blood vessel diameter and blood oxygenation detected all 10 pancreatic cancers; though the probe was less precise (63% accurate) in determining which of the healthy volunteers did not have cancer. The technique will now be tested in a much larger international clinical trial led by the Mayo Clinic researchers. The findings were presented at Digestive Disease Week 2012, held earlier this week in San Diego, CA.
About the author
Tami Freeman is editor of medicalphysicsweb.