Stretchable electronics device maps beating heart
Flexible electronics that can adhere to the surfaces of living, moving tissues such as the heart could be used to sense and control the electrical activity of these tissues. Now, researchers from Northwestern University (Evanston, IL), the University of Illinois (Urbana, IL) and the University of Pennsylvania (Philadelphia, PA) have demonstrated how a flexible electronics-based device can map the electrical activity in a beating pig's heart with sub-millimetre and sub-millisecond resolution (Sci. Transl. Med. 2 24ra22).
The 14.4 x 12.8 mm sensor includes 2016 silicon nanomembrane transistors and 288 contact points, and is engineered to operate when immersed in the body's fluids. By locating the electronic circuits next to the tissue, rather than remotely, the device can incorporate a much higher number of electrodes for sensing or stimulation than is currently possible in medical devices. "The heart is dynamic and not flat, but electronics currently used for monitoring are flat and rigid," said Younggang Huang, from Northwestern University. "Our electronics have a wavy mesh design so they can wrap around irregular and curved surfaces, like the beating heart. The device is thin, flexible and stretchable, and brings electronic circuits right to the tissue. More contact points mean better data."
Lymph node irradiation suitable after cancer surgery
A new study reveals that irradiating specific lymph nodes after surgery is well tolerated in patients with early breast cancer. In a cohort of 4004 patients, 76% had undergone breast-conserving surgery, followed by standard radiotherapy plus a boost. The remaining 24% underwent mastectomy, with three quarters of this group receiving chest-wall radiotherapy. Patients were randomized to receive radiotherapy to the lymph nodes behind the breast bone and above the collar bone, or no further lymph node therapy. At three years follow-up, there was no evidence of increased toxicity to the heart in patients who received the additional lymph node radiotherapy. Further follow-up will look for possible long-term damage to the heart or lungs.
The longer-term aim of the study, carried out by the EORTC radiotherapy and breast cancer groups (46 institutions from 13 countries), is to determine whether specific lymph-node radiotherapy improves overall survival. "We are hopeful that we will see a survival benefit of at least 5% in patients at the time of the primary analysis. With a median follow-up of over seven years, 558 patients have died, so the estimated 10-year overall survival rate of 79–83% is even above the anticipated range," said Philip Poortmans, from the Dr Bernard Verbeeten Instituut in the Netherlands, who presented the findings at the recent European Breast Cancer Conference (EBCC7) in Barcelona, Spain.
Nanoparticles provide targeted photothermal therapy
Scientists at Washington University in St Louis (St Louis, MO) have demonstrated successful photothermal treatment of tumours in mice using gold nanocages. When injected, the nanocages selectively accumulate in tumour tissue. Subsequent exposure to NIR light causes the cages to heat up and destroy the tumour – with minimum damage to surrounding healthy tissue. The thickness of the nanocage walls controls their resonance wavelength, which was tuned to 800 nm. "We saw significant changes in tumour metabolism and histology," said Michael Welch, professor of radiology and developmental biology. "This is remarkable given that the work was exploratory, the laser 'dose' had not been maximized, and the tumours were 'passively' rather than 'actively' targeted."
Mice bearing tumours were injected with PEG-coated nanocages, and several days later exposed to a diode laser for 10 minutes. Thermal imaging during irradiation revealed that the skin surface temperature increased rapidly from 32 to 54 ºC. In control mice injected with buffer solution, the temperature remained below 37 ºC. The researchers used PET/CT to monitor metabolic activity and saw that tumours in nanocage-injected mice were significantly fainter on the PET scans, indicating that many tumour cells were no longer functioning. The next step will involve creating nanocages that actively target tumour cells, and loading the particles with cancer-fighting drugs (Small 6 811).
Microsphere treatment shows promise for liver cancer
Intra-arterial yttrium-90 (Y-90) microspheres show promise for prolonging the life of patients with inoperable liver cancer. That's the conclusion of a study presented at the recent Society of Interventional Radiology Annual Scientific Meeting in Tampa, FL. The therapy uses the radioactive isotope Y-90 encapsulated in microspheres to deliver radiation directly to the tumour. This allows a higher, local dose of radiation to be used without subjecting healthy tissue to radiation. The microspheres, which are about the size of five red blood cells, are injected via a catheter into the liver artery supplying the tumour and become lodged within tumour vessels.
In the study, 291 patients with hepatocellular carcinoma were treated with intra-arterial Y-90 microspheres. The researchers administered 526 Y-90 treatments and reviewed 1250 scans to assess response and time-to-progression. The overall time-to-progression was 7.9 months. "In oncologic standards for this disease, this is a very promising finding," said Riad Salem, an interventional radiologist at Northwestern University (Chicago, IL). "While patients aren't cured, their lives are being extended and their quality of life is improving with Y-90 microsphere treatment."
FDG-PET may hold answers for patients with heart failure
PET imaging with the radiotracer 18F-fluorodeoxyglucose (FDG) can assess myocardial viability, to determine whether heart tissue would benefit from revascularization. Now, a study headed up at the University of Ottawa Heart Institute, Ontario, Canada has revealed a trend toward better patient outcomes when PET is used in diagnostic work-up of patients with heart failure (J. Nucl. Med. 51 567).
The researchers analysed data from a study comparing FDG-PET-directed management with standard clinical management of patients with coronary artery disease and poor left ventricular function. They showed that FDG-PET is useful for identifying patients who would benefit from bypass surgery or other procedures to improve blood flow, and that it has the potential to streamline management, reduce cost and improve survival. "We are confident that FDG-PET viability can be used to direct therapy," said lead author Robert Beanlands, chief of cardiac imaging at the University of Ottawa Heart Institute. "In cases where it is available, we recommend this course of action because it can improve patient care and patient outcomes."
Reducing radiation dose during coronary CTA
Reduced or no "padding" during ECG-triggered coronary CT angiography can substantially lower radiation dose without affecting image quality, according to research published in the American Journal of Roentgenology. During ECG-triggered coronary CT angiography – a minimally invasive procedure used to evaluate coronary artery blockages – there is a mandatory minimum time that the scanner must be on during each heartbeat. Typically, extra time is added before and after this, referred to as "padding". Reducing or eliminating this padding time shortens the scanner on-time and lowers the radiation dose (AJR 194 933).
The study – performed at Weill Cornell Medical College (New York, NY), Fairfax Radiological Consultants (Fairfax, VA) and the University of British Columbia in Vancouver, Canada – included 886 patients who underwent ECG-triggered coronary CT angiography with a padding duration of either 0, 1–99 or 100–150 ms. Increased padding was associated with a greater radiation dose (45% increase per 100 ms), but no difference in image interpretability was seen between the three groups. "Padding duration can be adjusted on a patient-by-patient basis, and decreased padding should be considered in dose reduction strategies for patients with excellent heart rate control," explained lead author Troy LaBounty, from Weill Cornell Medical College.