Simon Veldhoen MD, Presenter: Nothing to Disclose

Maximillian Schollchen, Abstract Co-Author: Nothing to Disclose

Henning Hanken, Abstract Co-Author: Nothing to Disclose

Clarissa Precht, Abstract Co-Author: Nothing to Disclose

Frank Oliver Gerhard Henes MD, Abstract Co-Author: Nothing to Disclose

Gerhard Schon, Abstract Co-Author: Nothing to Disclose

Hans Dieter Nagel, Abstract Co-Author: Consultant, Koninklijke Philips NV

Max Heiland MD, Abstract Co-Author: Nothing to Disclose

Gerhard B. Adam MD, Abstract Co-Author: Nothing to Disclose

Marc Regier, Abstract Co-Author: Nothing to Disclose

As an overlap of cone beam computed tomography (CBCT) and MDCT use for imaging in midfacial trauma can be observed, purpose of the study is to compare a state-of-the-art CBCT device and a 256-MDCT for imaging of the midface.

A CBCT device (3D Accuitomo, Morita) and a 256-MDCT (Brilliance iCT, Philips) were compared based on scans of 25 cadaver heads and phantoms. Scan protocols at three dose levels were generated (standard-dose, CTDIvol≈24mGy; reduced-dose, CTDIvol ≈9mGy; low-dose,CTDIvol≈4mGy). MDCT images were reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) (iDose4™, Philips Healthcare). Spatial resolution was assessed using a phantom (Catphan™ 500, The Phantom Laboratory). Objective image noise (OIN) was measured and four readers evaluated the subjective quality of the blinded images separately.

Using low-dose settings, spatial resolution of CBCT and MDCT was equal (10 identifiable line pairs (lp) per cm). At reduced- and standard-dose, CBCT was superior with 11/13 lp/cm compared to 10/11 lp/cm in MDCT. Concerning cadaver head scans, OIN was higher in FBP-MDCT images when compared to CBCT (standard dose, 33 vs. 82HU; reduced dose, 47 vs. 135HU; low-dose, 71 vs. 196HU). Iterative reconstruction was able to lower the OIN of MDCT images but except standard-dose they remained higher than in CBCT (standard-dose, 40HU; reduced-dose, 93HU; low-dose, 132HU). Subjective image quality was comparable at standard-dose (CBCT 3.5 vs. MDCT 3.7). CBCT was superior at reduced- and low-dose settings (CBCT, 3.3/3.0 vs. MDCT 2.9/2.3). At low-dose settings, MDCT images were of limited diagnostic quality. Image acquisition and reconstruction times were markedly higher for the CBCT device.

CBCT imaging provided better objective and subjective image quality at low-dose settings, when compared to MDCT whereas spatial resolution was equal. Similar performance was observed at higher exposure settings but CBCT then provided better spatial resolution. Modern CBCT devices seem to make use of noise-reduction techniques similar to IR as very low image noise and long reconstruction times were observed.

Due to the high resolution, dental imaging is the specific strength of CBCT. Long image reconstruction times and the inferiority in soft-tissue assessment are main limitations of CBCT use in midfacial trauma. Therefore, MDCT should be preferred for this purpose.

Veldhoen, S, Schollchen, M, Hanken, H, Precht, C, Henes, F, Schon, G, Nagel, H, Heiland, M, Adam, G, Regier, M, Diagnostic Performance of Cone Beam Computed Tomography and MDCT in Diagnostic Imaging of the Midface: A Comparative Study on Phantoms and Cadaver Head Scans.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006653.html