Digital mammographic artifacts on full-field systems: what are they and how do I fix them?

The recent introduction of digital mammography represents a significant technologic advance in breast imaging. However, many radiologists and technologists are unfamiliar with artifacts that are commonly seen with this modality, and recognizing these artifacts is critical for optimizing image quality. Commonly encountered artifacts include patient-related artifacts (motion artifact, antiperspirant artifact, thin breast artifact), hardware-related artifacts (field inhomogeneity, detector-associated artifacts, collimator misalignment, underexposure, grid lines, grid misplacement, vibration artifact), and software processing artifacts ("breast-within-a-breast" artifact, vertical processing bars, loss of edge, high-density artifacts). Although some of these artifacts are similar to those seen with screen-film mammography, many are unique to digital mammography--specifically, those due to software processing errors or digital detector deficiencies. In addition, digital mammographic artifacts depend on detector technology (direct vs indirect) and therefore can be vendor specific. It is important that the technologist, radiologist, and physicist become familiar with the spectrum of digital mammographic artifacts and pay careful attention to digital quality control procedures to ensure optimal image quality.

Coregistered tomographic x-ray and optical breast imaging: initial results.

We describe what is, to the best of our knowledge, the first pilot study of coregistered tomographic x-ray and optical breast imaging. The purpose of this pilot study is to develop both hardware and data processing algorithms for a multimodality imaging method that provides information that neither x-ray nor diffuse optical tomography (DOT) can provide alone. We present in detail the instrumentation and algorithms developed for this multimodality imaging. We also present results from our initial pilot clinical tests. These results demonstrate that strictly coregistered x-ray and optical images enable a detailed comparison of the two images. This comparison will ultimately lead to a better understanding of the relationship between the functional contrast afforded by optical imaging and the structural contrast provided by x-ray imaging.

Breast cancer detection by mapping hemoglobin concentration and oxygen saturation.

Near-infrared (NIR) spectroscopic imaging technology provides a new modality for measuring changes in total hemoglobin concentration (HbT) and blood oxygen saturation (SO2) in human tissue. The technology can be used to detect breast cancer because cancers may cause greater vascularization and greater oxygen consumption than in normal tissue. Based on the NIR technology, ViOptix, Inc., has developed an optical device that provides two-dimensional mapping of HbT and SO2 in human tissue. As an adjunctive tool to mammography, the device was preliminarily tested in a clinical trial with 50 mammogram-positive patients at the Massachusetts General Hospital. The results of the clinical trial demonstrate that the device can reach as much as 92% diagnostic sensitivity and 67% specificity in detecting ductal carcinoma. These results may indicate that the NIR technology can potentially be used as an adjunct to mammography for breast cancer detection to reduce the number of biopsies performed.

Tomographic optical breast imaging guided by three-dimensional mammography.

We introduce a modified Tikhonov regularization method to include three-dimensional x-ray mammography as a prior in the diffuse optical tomography reconstruction. With simulations we show that the optical image reconstruction resolution and contrast are improved by implementing this x-ray-guided spatial constraint. We suggest an approach to find the optimal regularization parameters. The presented preliminary clinical result indicates the utility of the method.