Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dartmouth researchers find new imaging method may lower risks for abdominal aortic aneurysms

03.04.2003


Results of a study by researchers at Dartmouth-Hitchcock Medical Center (DHMC) and Dartmouth Thayer School of Engineering could have implications for choosing which patients with abdominal aortic aneurysms should have surgery and which ones should simply have follow-up with noninvasive studies.



In an article published in the April issue of the Journal of Vascular Surgery, Dr. Mark Fillinger and colleagues describe a new noninvasive method for evaluating abdominal aortic aneurysms (AAA). They found that the new method – examining aneurysm wall stress – predicts AAA rupture risk better than aneurysm diameter, which has been used to predict rupture risk for over 40 years.

The multidisciplinary study was sponsored by the National Institutes of Health and the National Heart Lung and Blood Institute. In the study, conducted at Dartmouth-Hitchcock Medical Center, over 100 patients who had computed tomography scans (CT scans) during the course of routine care had AAA “wall stress analysis”. The CT scan is processed through a series of computer programs, including an engineering process called finite element analysis. Finite element analysis breaks the structure into thousands of tiny elements so a computer can calculate the wall stress using the three-dimensional shape of the AAA (from the CT scan), the patient’s blood pressure, and the tissue properties of typical AAAs. The result is a computer-generated “stress map” that displays the aneurysm wall stress (the force trying to pull the aneurysm apart and cause rupture).


The patients in the study were generally under observation for their aneurysm for one of three reasons: 1) because the aneurysm was felt to be too small to repair, 2) because the risks of repair were felt to be too high compared to the risk of aneurysm rupture, or 3) because the patient decided not to have aneurysm repair. The outcomes of observation were then compared based on the standard method of determining rupture risk (maximum AAA diameter) versus the maximum stress within the aneurysm wall. A prior study by this group had determined that wall stress was high at the time of rupture, but this was the first large study of AAA wall stress in patients under extended periods of observation.

Researchers found that the new technique (aneurysm wall stress analysis) predicted the risk of rupture better than maximum AAA diameter, with a 25 fold increase in rupture risk for patients with high AAA wall stress, and only 9 fold higher rupture risk for patients with large diameter (over 5.5 cm). The location of rupture (when known) was also consistent with the location of maximum stress predicted by the computerized stress map. Interestingly, some patients with small aneurysms had high wall stress (high risk of rupture) and some patients with large aneurysms had low wall stress (low risk of rupture).

“This study has several important aspects. Some patients with small aneurysms (based on diameter) have an unexpectedly high risk of rupture and should have surgery earlier than is typically recommended” says Dr Fillinger. “Other patients with larger aneurysms, but high risks for surgery, may delay surgery and have observation with noninvasive studies if we can reliably predict that they have a low rupture risk. Another impact of this study may be that blood pressure control in aneurysm patients will be examined with more scrutiny, since blood pressure plays a key role in AAA wall stress. We have made great strides with minimally invasive surgery for aortic aneurysms, but not everyone is a candidate for these techniques. AAA wall stress analysis may be able to prevent rupture in some patients and prevent unnecessary surgery in others."

The risk of rupture relative to AAA diameter and female gender (known risks for aneurysm rupture) were consistent with recent large clinical trials in the US and UK. In those studies, patients with AAAs under close observation with ultrasound every 6 months still had a small risk of rupture, with higher risks for women. “The consistency of our current study with the US and UK small aneurysm trials is encouraging. In future work, we hope to determine why females are at greater risk for rupture than males. We would like to improve the aneurysm tissue model, and hope to start a larger multicenter study within the next year.”

It is estimated that 2 million people in the US have abdominal aortic aneurysms, and AAA rupture is the thirteenth leading cause of death in men. Many people are unaware they have aortic aneurysms because they cause no symptoms prior to rupture. The increasing incidence of AAA nationwide has lead to more attention regarding screening for AAA, including a recent feature in the Wall Street Journal. Numerous famous people have died of AAA rupture, including Albert Einstein, Lucille Ball, and George C Scott. Senator Bob Dole and Rodney Dangerfield are among celebrities who have recently had AAA repair to prevent rupture.




Dartmouth-Hitchcock Medical Center (DHMC) is an integrated academic medical center located on a 225-acre campus in the heart of New Hampshire’s Upper Connecticut River Valley in Lebanon. DHMC comprises Mary Hitchcock Memorial Hospital, the Dartmouth-Hitchcock Clinic, Dartmouth Medical School and the Veterans Affairs Medical Center in White River Junction, VT.

For more information contact Tamsin Stubbs at (603) 653-1997.

Tamsin Stubbs | DHMC
Further information:
http://www.dhmc.org/webpage.cfm?site_id=2&org_id=2&morg_id=0&gsec_id=2&sec_id=2&item_id=16691

More articles from Health and Medicine:

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

nachricht A promising target for kidney fibrosis
21.04.2017 | Brigham and Women's Hospital

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>