During open surgery, doctors rely on their sense of touch to identify the edges of hidden tumors and to locate hidden blood vessels and other anatomical structures: a procedure they call palpation. But this practice is not possible in minimally invasive surgery where surgeons work with small, specialized tools and miniature cameras that fit through small incisions in a patient’s skin.
In order to provide the benefits of palpation to minimally invasive surgery, a team of engineers and doctors at Vanderbilt University headed by Pietro Valdastri, assistant professor of mechanical engineering and medicine, has designed a special-purpose wireless capsule equipped with a pressure sensor that fits through the small ports that surgeons use for what is also called “keyhole” surgery.
The system is described in an article in press at the journal IEEE Transactions on Biomedical Engineering.
Once in the body, the surgeon can grip the capsule with the jaws or wire loop on the end of the laparoscope he or she is using for the surgery and press the end of capsule against the target tissue. As the surgeon taps the capsule in different places, it sends information about its position and the force being applied to a computer that uses the data to produce a false-color map of the tissue stiffness. This map can reveal the location of tumors, arteries and other important structures that the cameras can’t see because they are covered by a layer of healthy tissue.
“This capsule provides physicians with haptic feedback – in other words, it restores our sense of touch,” said Keith Obstein, an assistant professor of medicine at Vanderbilt University Medical Center who is collaborating on the capsule’s development. Although the prototype is limited to providing this information on a computer screen, “once you have the data you can use it in a number of different ways,” he said. One possibility that he suggests is using the capsule data with a commercially available “haptic glove” that would allow the surgeon to feel pressure that the capsule is exerting and how the tissue is responding almost as if they are touching it directly.
“Because palpation is so important to surgeons, there have been several previous attempts to build instruments that can provide it,” said Valdastri. “Our approach is much simpler because it isn’t attached to a rigid shaft like previous tools and so does not force the surgeon to make an additional incision in the patient to use it.”
Although laparoscopy – the technical term for minimally invasive surgery – has been around for more than a century, its use has grown substantially in the last 20 years since medical researchers have demonstrated that it is not only safer but also less expensive than open surgery for a number of different types of operations. Currently, more than two million of minimally invasive procedures are performed annually in the United States.
“The hope behind something like this capsule is that the surgeon will be able to place it inside the body through an existing incision and leave it in a position where it can be easily grasped and used to map out the stiffness or density of the tissue when needed, much like he or she would palpate it with by hand in open surgery,” said collaborator S. Duke Herrell, associate professor of urologic surgery at Vanderbilt University School of Medicine.
The palpation capsule designed at Valdastri’s Science and Technology of Robotics in Medicine (STORM) Lab is extremely simple. It is 0.6 inches wide and 2.4 inches long. It contains a pressure sensor, an accelerometer, a wireless transmitter, a magnetic field sensor and a small battery.
The pressure sensor records how hard the end of the capsule is being pushed against its target. The accelerometer records its movements. The capsule is used with a fixed external magnet and its position is tracked precisely by measuring the strength and direction of the magnetic field it experiences. The wireless transmitter sends all this information to an external antenna connected to a computer that uses the data to draw the map of tissue stiffness.
In desktop testing with tissue simulated with silicone gel, the researchers report that the capsule can measure the local stiffness of the tissue with a relative error less than 5 percent. In large animal tests, they have achieved a relative error of 8 percent. The researchers goal is to achieve a level of resolution comparable to or greater than that of human touch.
Technical work on the capsule has been done in the STORM Lab by graduate students Marco Beccani and Christian Di Natali. Additional testing and biomechanical analysis of results have been performed in collaboration with graduate student Levin Sliker, Assistant Professor Mark Rentschler at the University of Colorado, Boulder, and Jonathan Schoen, associate professor of surgery at University of Colorado School of Medicine.
Valdastri hopes to get approval to test the device in clinical trials in the next five years.The research was funded by National Science Foundation grant CNS-1239355 and National Center for Advancing Translational Sciences grant UL1-TR000445-06.
Visit Research News @ Vanderbilt for more research news from Vanderbilt. [Media Note: Vanderbilt has a 24/7 TV and radio studio with a dedicated fiber optic line and ISDN line. Use of the TV studio with Vanderbilt experts is free, except for reserving fiber time.]Contact:
David F. Salisbury, | Vanderbilt University
True to type: From human biopsy to complex gut physiology on a chip
14.02.2018 | Wyss Institute for Biologically Inspired Engineering at Harvard
The Scanpy software processes huge amounts of single-cell data
12.02.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy