Henning Meyer MD, Presenter: Research grant, Koninklijke Philips Electronics NV, Best, Netherlands

Felix Diekmann MD, Abstract Co-Author: Nothing to Disclose

Susanne Dorothea Diekmann MD, Abstract Co-Author: Nothing to Disclose

Sylvie Puong PhD, Abstract Co-Author: Employee, General Electric Company

Ulrich Bick MD, Abstract Co-Author: Travel support, MeVis BreastCare GmbH & Co KG

Patrik Rogalla MD, Abstract Co-Author: Nothing to Disclose

With Tomosynthesis 1 mm thick slices can be generated from a series of different angulated digital mamographies. However these slices suffer from relativly high image noise. Furthermore due to the high number of slices tomosynthesis can be tedious to read. In an initial evaluation, we investigated the potential of different algorithms for generating 1 cm thick slices from tomosynthesis source data (maximum intensity projection - MIP; average algorithm - AV, and image generation by means of a new algorithm, so-called softMip).

Evaluation was performed using a 5 cm thick textured phantom which contained two 0.5 cm thick slabs to simulate microcalcifications, spiculated masses, and round masses. The phantom was examined by tomosynthesis (GE Healthcare). Microcalcifications were simulated by calcium particles of different sizes: a: 250-280 μm; c: 280-300 μm; d: 300-355 μm. Round masses (RM) and spiculated masses (SM) ranging from 1.45 mm to 4.0 mm in diameter. The reconstructed tomosynthesis were postprocessed using MIP, AV, and softMip to generate 1 cm thick slices. with a lower noise three postprocessing algorithms were assessed by calculating the resulting contrast versus the simulated microcalcifications and contrast-to-noise ratios (CNR) for the other objects were assessed for the three postprocessing techniques.

The CNR of RM and SM were highest for the thick slices generated with the average algorithm, followed by softMip and MIP. Contrast of the simulated microcalcifications was best for MIP, followed by softMip and average projection.

The three algorithms investigated have different advantages and disadvantages. SoftMip is a new approach combining advantages of MIP and Average projection. SoftMip images depict low contrast objects and microcalcifcations with a slightly higher noise level than average and a slightly lower contrast than MIP.

In conclusion, our results suggest that the additional generation of thick slices improves the visualization of objects in tomosynthesis.

Meyer, H, Diekmann, F, Diekmann, S, Puong, S, Bick, U, Rogalla, P, Evaluation of Different Projection Algorithms for Tomosynthesis to Generate Thick Slices.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5008809.html