Hiroko Iijima MD, Presenter: Nothing to Disclose

Peter Burns PhD, Abstract Co-Author: Nothing to Disclose

Tae Kyoung Kim MD, Abstract Co-Author: Nothing to Disclose

Hyun-Jung Jang MD, Abstract Co-Author: Nothing to Disclose

Marcus Dill-Macky MBBS, Abstract Co-Author: Nothing to Disclose

Stephanie Ruth Wilson MD, Abstract Co-Author: Nothing to Disclose

Fuminori Moriyasu, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Compared to contrast agents of other modalities and to red blood cells themselves, ultrasound contrast agents are extremely sparse in the circulation: a typical dose might produce a maximum of about 100 bubbles per ml of blood, of which only a few resonate and contribute to the image. Given the low flow velocities in the microcirculation and the brief period used to form an image, it is thus inevitable that the pattern of enhancement in current contrast imaging samples the location of bubbles in small vessels rather than the vessels themselves. Maximum intensity projection (MIP) processing is a simple method that integrates the images between frames, effectively ‘tracking’ the route that individual bubbles take. The result is a new kind of image showing the path of microvessels.

Normal tissue and tumors were examined in 20 patients with focal liver lesions and 10 rabbits with VX2 carcinoma, using bolus injections of Definity (Bristol-Myers Squibb, Boston MA) and pulse inversion imaging (Philips HDI5000, Bothell WA; Toshiba Aplio, Tokyo Japan) at low MI. MIP processing was initiated after a high MI bubble-disruption flash during breath hold. Images were integrated to the point at which tissue motion degraded the image, usually 1-3 seconds.

In all cases the images showed increased spatial detail of small blood vessels, unvisualized on conventional and contrast ultrasound imaging, up to the 6th order branches of the portal vein. The method showed superior morphological structure of tumor vessels and dramatically enhanced such diagnostic features as peripheral nodular enhancement of haemangiomas and stellate patterning of focal nodular hyperplasia. Tissue motion artifact was the limiting challenge in patient imaging.

MIP contrast imaging adds new capability to vascular imaging with contrast ultrasound and helps overcome one fundamental limitation of microbubble contrast: the low number of scatterers injected. It is particularly effective in lesions where flow volume is low and tissue motion is controllable for 1-2 seconds. In addition to the liver, the method has potential for lesion imaging in the kidney, breast and lymph nodes.

Iijima, H, Burns, P, Kim, T, Jang, H, Dill-Macky, M, Wilson, S, Moriyasu, F, et al, , Pulse Inversion Contrast Imaging of the Liver with Maximum Intensity Projection Processing.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4416656.html