New hope for tiny hearts

"Making the correct diagnosis is the greatest challenge facing paediatric cardiologists," explains Siri-Ann Nyrnes, Consultant at the Paediatric Department of St. Olav's Hospital. "The organs are so small, and current ultrasound imaging can only provide limited information. A cardiologist needs many years of experience to be able to make a diagnosis with any certainty." Dr Nyrnes is part of the Medical Imaging Laboratory (MI Lab), whose host institution is the Norwegian University of Science and Technology (NTNU).

MI Lab is one of Norway's 14 original Centres for Research-based Innovation (SFI) which have received funding from the Research Council of Norway since 2007.

New imaging of blood flow

Colour Doppler imaging has been the standard in ultrasound since the late 1980s. MI Lab's new method, called blood flow imaging (BFI), provides two-dimensional blood flow information by visualising blood speckle movement superimposed on colour Doppler images. The resulting pattern displays blood flow regardless of the ultrasound beam orientation -- providing greater information about flow direction as well as a more intuitive visualisation. Blood flow rate can also be measured, and doctors will soon be able to determine the actual volume of blood flowing through normal and pathological openings.

In a pilot study, researchers examined 13 children with ventricular septal defect (a hole in the wall between the right and left ventricles of the heart, the most common heart defect in newborns). Using both new and conventional blood flow imaging methods, the researchers concluded that compared to the colour Doppler, the new method provides a significantly more detailed image of blood flow.

3D imaging in future

"The images in this study were created by the physician and technician working together, so the latter could see first-hand what we physicians are contending with, and what we need in order to improve our diagnostics," says Dr Nyrnes. "The method is being refined with each patient."

Now MI Lab is taking the method a step further by using plane wave imaging, which can generate an image more quickly. A pilot study of five newborns indicated that plane wave imaging yielded 5-10 times more images per second, with a substantially higher image quality.

"Quantifying the blood flow is our next objective," says engineer and research fellow Lasse Løvstakken. "Ultimately we want to develop this method to provide blood flow information in 3D."