• Digital Mammography
  • Breast care
    without compromise
  • Convenient and effective
  • Excellent image quality
  • Insight View ^NEW
  • Tomosynthesis
  • Many questions -
    one answer
• Digital biopsy
  • Expand your
    diagnostic bandwidth
  • Better access
  • Safe procedures
  • Confirm-X ^NEW
• Analog mammography
  • Ergonomy and comfort
  • Analog with digital biopsy

TOMOSYNTHESIS - coming in 2010

Why Tomosynthesis?
The clinical need

Early detection using screening mammography has been shown to significantly reduce the mortality associated with breast cancer.

The introduction of full-field digital mammography in the last few years has improved image quality and has been shown to improve sensitivity in the dense breast 2. However, FFDM relies on 2D projection images, in which pathological structures can be obscured and thus remain undetected. Furthermore, overlapping structures can mimic lesions, leading to false positive results. The complex projection images from conventional mammography present a difficult diagnostic challenge: interpreting multiple layers of overlapping tissue projected into a 2D image.

There is a clear unmet clinical need for a breast imaging modality that can provide high resolution 3D imaging while remaining within both the X-ray 'dose budget' and the financial budget of traditional 2D mammography. This is the clinical need that digital breast tomosynthesis (DBT) addresses.

DBT is a powerful tool that can improve the early detection of breast cancer, particularly in the dense breast. It is a new and advanced technique to better support the radiologist in the daily fight against breast cancer. IMS is dedicated to providing its customers with the most advanced and innovative devices. We present here our own vision of Tomosynthesis: an optimised and original solution capable of providing spectacular clinical results.

Left image: Detail from a plane of a tomosynthesis data set (below) acquired with the IMS prototype. The detail clearly shows the mass, which is less clear in the detail from a digital mammogram of the same breast. Right image: A tomosynthesis slice acquired with the IMS prototype.

Key Differences between Optimized IMS Tomosynthesis and Naive Tomosynthesis

Not all Tomosynthesis systems are designed in the same way and this may lead to different clinical performance between systems. IMS has developed a Tomosynthesis device, using patented solutions, with optimised geometry, dose distribution and advanced reconstruction methods. The table below summarises key differences between approaches:

How has IMS optimised Tomosynthesis?

IMS is developing a second generation DBT device that implements unique, patented optimizations to provide the best image quality at the lowest dose to the patient. This device is the result of ten years of research and clinical study into advanced reconstruction methods, optimal imaging geometries, variable dose distributions3 and novel Tomosynthesis visualization methods for efficient workflow.

Other Tomosynthesis approaches still use CT style filtered back projection (FBP) reconstruction algorithms and geometries with uniform distribution of dose and projection angles.

The IMS DBT system uses methods that are optimal for Tomosynthesis, not for CT. These methods cover, among others, reconstruction algorithms, dose distribution and spacing of images.

Variable dose & central exposure

One special implementation of IMS's optimised variable dose geometry uses sufficient dose in the central projection for that image to be a 2D mammogram. The reconstruction algorithm makes full use of the extra information provided by this high contrast central image.

Digital detector

The IMS Tomosynthesis solution uses the 24x30 cm 2nd Generation Amorphous Selenium detector manufactured by Anrad, Canada. It has been designed especially for DBT and has a very fast read time, the highest DQE at low dose and we have verified its reliability during 7 years of clinical use in FFDM. One of the features that make it ideal for Tomosynthesis applications is the absence of ghosting effects.

3D reconstruction algorithms

The choice of advanced iterative, non-linear reconstruction methods, rather than the more common filtered back projection (FBP) method, allows the use of IMS's optimized variable geometry and decreases noise and image artefacts. FBP is ideal for fully-sampled CT in which information is acquired from a full 360 degree scan.

When used in under-sampled Tomosynthesis, FBP is sub-optimal and generates streaking artefacts and noise. It may also filter out real structures in its efforts to suppress artefacts. IMS's advanced reconstruction methods allow superior image quality (as shown in the tomo slice, left) to be achieved at a lower dose to the patient.