Atul Padole MD, Presenter: Nothing to Disclose

Sarabjeet Singh MD, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Toshiba Corporation Research Grant, General Electric Company Research Grant, Koninklijke Philips NV

Diego Alfonso Lira MD, Abstract Co-Author: Nothing to Disclose

Sarvenaz Pourjabbar MD, Abstract Co-Author: Nothing to Disclose

Ranish Deedar Ali Khawaja MD, Abstract Co-Author: Nothing to Disclose

Mannudeep K. S. Kalra MD, Abstract Co-Author: Nothing to Disclose

Alexi Otrakji MD, Abstract Co-Author: Nothing to Disclose

Roberto Lo Gullo MD, Abstract Co-Author: Nothing to Disclose

To assess diagnostic image quality in post mortem chest CT acquired at eight different dose levels and reconstructed with FBP, ASIR and MBIR techniques.

In an IRB approved, post mortem chest CT was performed in 40 human cadavers (57±13years, body mass index 26±6, F:M 13:27) at eight different dose levels with mean CTDIvol of 3.7-15 mGy at 100-120 kV and 10-40 noise index (NI) on a 64 channel MDCT (GE Discovery CT750 HD). The remaining scan parameters were held constant at pitch of 0.984:1, rotation time of 0.5 second. Sinogram data at each dose level were reconstructed with FBP, ASIR (SS50, GE Healthcare) and MBIR (Veo, GE Healthcare) (n= 8*3*40= 960 series). Radiologist performed independent and blinded comparison of one image series at a time for lesions detection, lesions conspicuity, and visibility of small structures. In addition, subjective image noise and artifacts were also assessed. Objective image noise was measured at each dose levels.

There were total 256 lesions detected on 15 mGy. In mediastinal window, at CTDIvol of 5.7 mGy lesions conspicuity was acceptable for 40/71 with FBP, 59/71 with ASIR, and 67/71 with MBIR. Similary, visibility of small structures was acceptable in 8/40 with FBP, 23/40 with ASIR and 40/40 with MBIR. At CTDI vol of 3.7 mGy, lesion conspicuity was acceptable for 21/71 with FBP, 27/71 with ASIR, and 57/71 with MBIR. Visibility of small structures was acceptable in 1/40 with FBP, 1/40 with ASIR and 20/40 with MBIR. In lung window, at all dose levels, lesion conspicuity and visibility of small structures were equally seen on FBP, ASIR, and MBIR. At CTDIvol of 3.7 mGy, lesions conspicuity was acceptable for 50/57 with FBP, 49/57 with ASIR, and 50/57 with MBIR. Similary, visibility of small structures was acceptable in 38/40 with FBP, 39/40 with ASIR and 39/40 with MBIR. For all dose levels, subjective image noise and artifact were lower with MBIR compared to FBP and ASIR. In addition, for all dose level, objective image noise was significantly lower for MBIR compared to FBP and ASIR (p<0.001). 

MBIR improves the mediastinal lesion conspicuity and visibility of small structures in post mortem chest CT performed at CTDIvol down to 3.7 mGy when compared to ASIR and FBP. 

Mediastinal structures can be better seen with iterative reconstruction techniques at CTDIvol of 3.7 mGy, where FBP technique is suboptimal.

Padole, A, Singh, S, Lira, D, Pourjabbar, S, Khawaja, R, Kalra, M, Otrakji, A, Lo Gullo, R, Comparison of Filtered Back Projection (FBP), Adaptive Statistical Iterative Reconstruction (ASIR) and Model Based (MBIR) Iterative Reconstruction Techniques for Post Mortem Chest CT Acquired at Eight Different Dose Levels.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004289.html