Hyun-Ju Lim MD, Presenter: Nothing to Disclose

Myung Jin Chung MD, Abstract Co-Author: Patent agreement, General Electric Company Patent agreement, Samsung Electronics Co Ltd

Kyung Eun Shin MD, Abstract Co-Author: Nothing to Disclose

Miyeon Yie, Abstract Co-Author: Nothing to Disclose

Hye Sun Hwang, Abstract Co-Author: Nothing to Disclose

Kyung Soo Lee MD, PhD, Abstract Co-Author: Nothing to Disclose

To compare the radiologists’ performance for the evaluation of diffuse interstitial lung disease (DILD) on CT images reconstructed with Model Based Iterative Reconstruction (MBIR), Adaptive Statistical Iterative Reconstruction (ASIR), and conventional Filtered Back Projection (FBP)

Included were 23 subjects (5 normal, 11 usual intersitial pneumonia(UIP), and 7 nonspecific interstitial pneumonia(NSIP); 13 men, 20 women; mean age, 64 ± 6 years) who underwent high dose thin section non-helical CT (HRCT, 1.25mm thickness, 100 – 300mA with dose modulation) and low dose helical CT (LDCT, 0.625mm x 64 rows with 0.984 pitch, fixed 40mA with 0.5 sec rotation). CTDI was 1.87 ± 0.01 mGy and 21.5 ± 5.5 mGy for LDCT and HRCT, respectively. LDCT was reconstructed using FBP, 50% ASIR, and MBIR. Matching images from four subsets were blinded and randomly sorted. Four board certified radiologists independently reviewed shuffled images. Semi-quantitative results for the extent of abnormalities (GGO, ground glass opacity; RET, reticular or honeycombing opacity; CON, consolidation) and confidence scores for disease status (normal vs. abnormal; UIP vs. NSIP) were compared.

The difference of overall diagnosis in presence of disease did not reach statistical significance (The AUCs for detection of DILD by HRCT, FBP, ASIR and MBIR were as follows: 0.978, 0.979, 0.972 and 0.963.). There was a trend of underestimation than HRCT of RET (-2.8%, -4.1%, and -5.3% in FBP, ASIR, and MBIR, respectively) and overestimation of GGO (+4.6%, +8.9%, and +8.5% in FBP, ASIR, and MBIR, respectively). However, no significant difference was found among above mentioned reconstruction methods for decision making on type of DILD (The AUCs for differentiation of UIP vs. NSIP by HRCT, FBP, ASIR and MBIR were as follows: 0.780, 0.805, 0.785 and 0.778).

LDCT with MBIR showed similar diagnostic performance to HRCT for typical DILD cases with reduced image noise in spite of much lower dose (less than 1/10). However, our study confirmed more caution is needed for comparing the disease extent especially on follow up studies reconstructed with iterative recontruction (IR) due to its possible influence on characterization of the interstitial lung disease pattern.

IR has potential to distort the perception of extent and character of DILD. Further caution is needed for radiologists in evaluating DILD using IR.

Lim, H, Chung, M, Shin, K, Yie, M, Hwang, H, Lee, K, Model Based Iterative Reconstruction in Chest CT: Influence to the Low-contrast High Spatial Frequency Lung Abnormalities in Diffuse Interstitial Lung Disease.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044112.html