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ECR 2013 / C-0595
A new method for radiation dose reduction at cardiac CT with multi-phase data-averaging and non-rigid image registration: preliminary clinical trial
Congress: ECR 2013
Poster No.: C-0595
Type: Scientific Exhibit
Keywords: Cardiac, Cardiovascular system, CT, CT-Angiography, Image manipulation / Reconstruction, Comparative studies, Technical aspects, Cardiac Assist Devices
Authors: F. Tatsugami, T. Higaki, M. Kiguchi, S. Date, K. Awai; Hiroshima/JP
DOI:10.1594/ecr2013/C-0595

Results

The mean heart rate during the acquisition of CT scans was 51.9 ± 5.1 bpm (range 45 - 63 bpm); the mean effective radiation dose was 4.9 ± 1.1 mSv.

 

Our quantitative image quality parameters are shown in Table 1. The mean image noise on the de-noised images was significantly lower than on conventional 75% images (P < 0.01). The CNR in the proximal coronary arteries was significantly higher on de-noised- than conventional 75% images (P < 0.01). With our method, image noise was reduced by 20.6 ±3.6% and CNR was increased by24.4 ± 6.4 % in the proximal RCA and by 25.4 ± 6.4 % in the LMA over conventional 75% images.

 

Table 1
References: Diagnostic Radiology, Hiroshima University - Hiroshima/JP

 

 

The noise reduction rate (%) increased proportionally with the time for the R-R interval (msec) (Pearson correlation r = 0.42, P = 0.02) (Fig. 3).

 

Fig. 3: Noise reduction rate (%) increased in proportion to the time for the R-R interval (msec) (Pearson correlation, r = 0.42, P = 0.02). Since the noise reduction rate increased in proportion to the time for the R-R interval, we suggest that our method is applicable in patients with a lower heart rate.
References: Diagnostic Radiology, Hiroshima University - Hiroshima/JP

 

 

The mean image quality score for conventional 75%- and de-noised images was 3.9 and 4.4, respectively; the difference was significant (P < 0.01) (Fig. 4-6). There was substantial interobserver agreement with respect to overall image quality (κ = 0.74). Representative cases are shown in Figs. 7 and 8.

 

Fig. 7: A 51-year-old man with a body mass index of 22.0 kg/m2 who was referred for noninvasive assessment of coronary artery stent patency. The images are curved multiplanar reconstructions of the left anterior descending coronary artery. (a) Conventional 75% image. The image noise was 22.3 HU and CNR in the left main coronary artery was 19.4 and the image quality was rated as good. (b) De-noised image. The image noise was 17.4 HU and CNR in the left main coronary artery was 24.5 and the image quality was rated as excellent.
References: Diagnostic Radiology, Hiroshima University - Hiroshima/JP

 

Fig. 8: A 76-year-old man with atypical chest pain and risk factors for coronary artery disease. The curved multiplanar reformation shows about 75% stenosis of the proximal left anterior descending coronary artery due to atherosclerotic plaque. (a) Conventional 75% image. The image noise was 25.2 HU and CNR in the left main coronary artery was 16.3 and the image quality was rated as good. (b) De-noised image. The image noise was 20.5 HU and the CNR in the left main coronary artery was 20.1 and the image quality was rated as excellent.
References: Diagnostic Radiology, Hiroshima University - Hiroshima/JP
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