Multimodal Ultrasound Tomography Correctly Spots Breast Cancer Lesions

Becky McCall

March 14, 2011

March 14, 2011 (Vienna, Austria) — In the first such clinical trial to date, a novel 3-dimensional (3D) diagnostic imaging technology for the detection of breast cancer, called multimodal ultrasound tomography (MUT), has correctly identified 49 malignant and 62 benign lesions in 64 volunteers. All lesions were confirmed with histopathologic analysis.

Vasilis Marmarelis, PhD, the inventor of the MUT technology and professor of biomedical engineering at the University of Southern California, Los Angeles, presented the initial clinical results with MUT here at the European Congress of Radiology (ECR) 2011.

"MUT is unique in its lesion differentiation capability that distinguishes malignant from benign lesions noninvasively and its ability to detect breast lesions as small as 2 mm in size in 3D breast images, even in dense or silicon-augmented breasts. The results to date are rather encouraging. These are preliminary results and require more clinical data and analysis, but they do provide initial confirmation of the ability of MUT technology to detect and differentiate suspicious lesions discernible in mammograms," reported Dr. Marmarelis.

MUT uses ultrasound, eliminating x-ray ionizing radiation, and does not require breast compression so is more comfortable for the patient.

MUT technology performs a 3D tomographic scan of the female breast suspended in a water bath, using transmission-mode ultrasound in a fixed-coordinate system. It represents a significant evolution of the pioneering work conducted at the Mayo Clinic in the 1970s, and is distinct from other previous or current efforts in this regard.

The patient lies prone, and the breast is suspended freely in continuously degasified, deionized, filtered, and sanitized water contained in a cylindrical scanning chamber. The chamber contains parallel sets of transmitting and receiving ultrasound arrays that perform transmission tomography over a 16-cm field of view for multiple view angles and elevations. Pixel size is 0.25 × 0.25 mm, and the separation between adjacent coronal scans ranges from 2 to 4 mm, depending on the clinical needs of the radiologist.

MUT differentiates noninvasive lesions using a combination of the refractive, dispersive, and frequency-dependent attenuation attributes of each voxel in the 3D image, Dr. Marmarelis explained. This lesion differentiation capability is unique to transmission-mode ultrasound tomography and is not achievable with reflection-mode ultrasound imaging, which is used extensively in current clinical practice.

In this clinical study, 64 female volunteers (median age, 59 years) who were mammographically characterized as having American College of Radiology Breast Imaging Reporting and Data System scores of 3, 4, or 5 underwent 3D MUT scans lasting 12 minutes per breast. Because MUT use is off-label, established clinical procedures were followed (usually biopsy or possible surgery) regardless of the MUT results.

Histopathologic analysis of the biopsied or excised lesions yielded 49 malignant and 62 benign lesions, ranging in size from 3 to 38 mm. Reliable noninvasive differentiation of benign and malignant lesions has been achieved in all cases to date.

Bar M. ter Haar Romeny, PhD, from Eindhoven University of Technology, the Netherlands, confirmed that the results show great promise. "Normally, a breast is investigated with x-ray, magnetic resonance imaging [MRI], dynamic contrast-enhanced MRI, or regular ultrasound. Dr. Marmarelis and his team have developed a breakthrough ultrasound tomography technique."

Dr. ter Haar Romeny explained that because the breast is rather homogeneous tissue, with no air and no bones, this method works well. With this technique, it is possible to measure elastic and mechanical tissue properties, such as the stiffness of a (palpable) nodule. "This system is capable of finding even tiny nodules, also deep in the breast. The results I have seen were quite impressive. The applied physics of the method are solid and well understood. Because it is a tomographic technique, the location of the lesion is known exactly, so it is a natural step to integrate a stereotactically or robot-controlled biopsy system with it," he said.

"I certainly [commend the ECR's] attention to this new development. The method is safe with no radiation and no contrast. It needs to be refined to an efficient and well-validated method for breast cancer screening and detection," he told Medscape Medical News.

Initial development was supported by the USC Alfred Mann Institute (2000 to 2006). Prototype development and clinical testing was supported by MastoScopia S.A. (2006 to 2011). Dr. ter Haar Romeny has disclosed no relevant financial relationships.

European Congress of Radiology (ECR) 2011: Poster C-1135. Presented March 4, 2011.


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