Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


MRI techniques improve pulmonary embolism detection

New research shows that the addition of two magnetic resonance imaging (MRI) sequences to a common MR angiography technique significantly improves detection of pulmonary embolism, a potentially life-threatening condition traditionally diagnosed through computed tomography (CT). Results of the study are published online in the journal Radiology.

Pulmonary embolism occurs when a blood clot—usually from the leg—travels to the lung and blocks the pulmonary artery or one of its main branches. CT angiography is the gold standard for diagnosis, but it exposes patients to ionizing radiation and iodinated contrast agent, which carries a risk of allergic reactions and kidney damage in some patients.

"MRI is developing much faster than CT," said Diego R. Martin, M.D., Ph.D., head of the Department of Radiology at the University of Arizona College of Medicine in Tucson. "The images we're getting are already significantly better than they were a year ago. There is no doubt that in the future we will be able to offer a non-radiation-based alternative to CT for the diagnosis of pulmonary embolism."

MRI has been used for pulmonary embolism detection in pregnant women and patients whose kidneys may be harmed by CT angiography contrast agents. However, the Prospective Investigation of Pulmonary Embolism Diagnosis III (PIOPED III) study, a major multicenter trial, found that centers had difficulty obtaining adequate quality MR pulmonary angiography (MRPA) for suspected pulmonary embolism. The PIOPED researchers determined that MRPA should be considered only at centers that routinely perform it and perform it well, and for patients who have contraindications to standard tests.

In the new study, the research team assessed the impact of two additional MRI sequences on MRPA's accuracy. The two techniques—contrast-enhanced volumetric interpolated breath-hold examination (VIBE) and non-contrast true fast imaging with steady-state precession (true FISP)—complement MRPA, according to Dr. Martin.

The addition of VIBE provides a gray scale that enables readers to distinguish between the clot, or thrombus, and the lung, which both appear dark on MRPA.

"Also, VIBE is not time sensitive," Dr. Martin said. "If the patient coughs, you can do it again. You don't have that option with MRPA."

The true FISP test does not require contrast agent or a breath hold, an important consideration for embolism patients who often cannot hold their breath long enough for image acquisition on MRPA.

When Dr. Martin and colleagues studied the three techniques on 22 patients with CTA diagnosis of pulmonary embolism, they found a sensitivity of 55 percent, 67 percent and 73 percent for MRPA, true FISP and VIBE, respectively. Combining all three MRI sequences improved the overall detection rate to 84 percent. Specificity was 100 percent for all detection methods except for MRPA, which demonstrated one false positive.

Dr. Martin hopes his findings stimulate discussion of a new, redesigned PIOPED study.

"PIOPED III did not answer the question of whether or not MRI is a useful alternative to CT, because it didn't use all the tools available," he said.

The MRI sequences used in the study are offered on all the major vendor systems, according to Dr. Martin, with the entire three-sequence protocol taking only 15 minutes to set up and perform.

"MR Imaging of Pulmonary Embolism: Diagnostic Accuracy of Contrast-enhanced 3D MR PulmonaryAngiography, Contrast-enhanced Low–Flip Angle 3D GRE, and Nonenhanced Free-induction FISP Sequences." Collaborating with Dr. Martin were Bobby Kalb, M.D., Puneet Sharma, Ph.D., Stefan Tigges, M.D., M.S.C.R., Gaye L. Ray, N.P., Hiroumi D. Kitajima, Ph.D., James R. Costello, M.D., Ph.D., and Zhengjia Chen, Ph.D.

Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc. (

RSNA is an association of more than 48,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (

For patient-friendly information on MR angiography, visit

Linda Brooks | EurekAlert!
Further information:

More articles from Medical Engineering:

nachricht Gentle sensors for diagnosing brain disorders
29.09.2016 | King Abdullah University of Science and Technology

nachricht New imaging technique in Alzheimer’s disease - opens up possibilities for new drug development
28.09.2016 | Lund University

All articles from Medical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel light sources made of 2D materials

Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.

So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Prototype device for measuring graphene-based electromagnetic radiation created

28.10.2016 | Power and Electrical Engineering

Gamma ray camera offers new view on ultra-high energy electrons in plasma

28.10.2016 | Physics and Astronomy

When fat cells change their colour

28.10.2016 | Life Sciences

More VideoLinks >>>