Wilfried Schneider

Integrated wavelets for enhancement of microcalcifications in digital mammography

This paper presents a new algorithm for enhancement of microcalcifications in mammograms. The main novelty is the application of techniques we have developed for construction of filterbanks derived from the continuous wavelet transform. These discrete wavelet decompositions, called integrated wavelets, are optimally designed for enhancement of multiscale structures in images. Furthermore, we use a model based approach to refine existing methods for general enhancement of mammograms resulting in a more specific enhancement of microcalcifications. We present results of our method and compare them with known algorithms. Finally, we want to indicate how these techniques can also be applied to the detection of microcalcifications. Our algorithm was positively evaluated in a clinical study. It has been implemented in a mammography workstation designed for soft-copy reading of digital mammograms developed by IMAGETOOL, Germany.

Visualization of microcalcifications by full-field digital mammography using a wavelet algorithm.

Abstract Purpose : A method is presented for visualizing microcalcifications by full-field mammography using wavelet frames, an enhancement operator, and a suitable reconstruction technique. Material and methods : The computer algorithm is tested on 24 digital mammographies (Senographe 2000D, GE Medical Systems) containing microcalcifications. This algorithm highlights microcalcification-like structures by means of a filter bank that is based on wavelet decomposition. What is new about this filter bank is that the discretization of the continuous wavelet transformation is specifically adjusted to the problem of image analysis, allowing for a better discrimination of microcalcifications from the image background. Results : In all cases (24/24), microcalcifications were depicted with a markedly higher contrast. Conclusion : Special computer algorithms improve the visualization of microcalcifications. This means in principle, that there is a potential to improve diagnostic assessment.

Computerassistierte Radiologie (CAR) in der Mammographie

Die Treffsicherheit bei der Beurteilung pathologischer Zustande an Hand radiologischer Bilder ist von apparativen Einflusgrosen und subjektiven Wahrnehmungen gepragt. In der vorliegenden Arbeit stellen wir eine die Befundung objektivierende Methode vor, mit deren Hilfe computerassistiert speziell mikrokalkformige Strukturen in Mammographien hervorgehoben werden konnen. Die Uberprufung der Methode an uber 100 in einem DICOM-Archiv des IT-ASSIST gespeicherten Bildern mit gesicherten Befunden zeigt, dass sie unterstutzend beim Auffinden von Mikrokalk im Rahmen der Mammographie vorteilhaft einsetzbar ist.

MammoInsight Computer Assisted Detection: Performance Study with Large Database

We extend our previous publications by presenting results on a large number of mammograms digitized with a laser scanner and analyzed by our MammoInsight CAD-system for the detection of clustered microcalcifications. We measure sensitivities on a per breast basis and on a per cluster basis for our system and show how they interrelate. We compare the performance of our system to the state-of-the art in the research literature. Finally, we show that our CAD-system is able to obtain a high sensitivity per breast, justifying it’s use in a clinical environment.

An integrated approach to computer-assisted diagnosis in digital mammography

Abstract This paper presents new techniques for the enhancement and detection of clustered microcalcifications in mammograms. They allow the integration of different existing mammographic imaging devices such as film or direct digital mammography. Using a wavelet image compression optimized for radiologic images, these techniques are integrated in a teleradiology workflow. This integrated system—open to existing infrastructure using only interfaces based on the DICOM standard—provides an excellent environment for large scale mammography screening programs.

Integrated wavelets for medical image analysis

Integrated wavelets are a new method for discretizing the continuous wavelet transform (CWT). Independent of the choice of discrete scale and orientation parameters they yield tight families of convolution operators. Thus these families can easily be adapted to specific problems. After presenting the fundamental ideas, we focus primarily on the construction of directional integrated wavelets and their application to medical images. We state an exact algorithm for implementing this transform and present applications from the field of digital mammography. The first application covers the enhancement of microcalcifications in digital mammograms. Further, we exploit the directional information provided by integrated wavelets for better separation of microcalcifications from similar structures.