Evaluation of image quality in different kV settings using different reconstruction algorithms in CT angiography of the aorta

Congress:

ESCR 2014

Poster Number:

453

Type:

Scientific Poster

Keywords:

Contrast agent-intravenous, CT-Angiography, Arteries / Aorta, Kv imaging

Authors:

M. Kok, C. Mihl, J. Turek, J. E. Wildberger, M. Das; Maastricht/NL

DOI:

DOI-Link:

https://dx.doi.org/

Fig. 1: Thoraco-abdominal aorta of the circulation phantom

Fig. 2: Mean signal noise of the aorta ascendens (AA) for FBP and IR of each kV setting

Fig. 3: Mean signal-to-noise ratio in the aorta ascendens (AA) for FBP and IR of each...

Purpose

Lower kV settings result in lower radiation dose while attenuation increases. Iterative reconstruction (IR) proved potential in reducing image noise compared to filtered back protection (FBP). Purpose was to evaluate image quality at lower kV settings and reconstruction with IR and FBP in CTA.

Methods and Materials

Contrast media (Iopromide 300mg/ml) was injected in a circulation phantom (fig. 1). A CTA of the thoraco-abdominal aorta with a fat ring simulating abdominal profile was obtained using different kV settings (120/100/80/70). Scan protocol was as follows: 128x0.6mm coll., pitch 0.75, mAsref 210, rot.time 0.28s. A standard injection protocol (iodine delivery rate=1.4gI/s; flow rate=4.7ml/s; volume=62ml; saline flush=14ml) was used (scan delay: test bolus technique). Image reconstruction: 2mm/1.4mm slice thickness using FBP (B30f) and IR (I30f, strength 3). Attenuation values (HU) as well as image noise...

Results

FBP image noise and SNR were: 15.2±1.3HU and 24.2±2.7(120kV); 20.1±1.9HU and 24.7±3.1(100kV) 38.4±2.9HU and 18.9±1.8(80kV) 58.3±5.5HU and 15.4±2.0(70kV). IR image noise and SNR were: 11.7±1.1HU and 32.7±3.7(120kV); 15.2±1.2HU and 32.6±3.2(100kV); 28.5±2.3HU and 25.2±2.3(80kV); 45.1±3.8HU and 19.9±2.6(70kV) (fig 2 and 3). Between FBP 120kV and IR 100kV, comparable image noise (15.2±1.3vs.15.2±1.2HU) and significant increased SNR (24.2±2.7vs.32.6±3.2) were found (p<0.03). Comparable SNR was obtained between FBP 100kVvs.IR 80kV (24.7±3.1vs.25.2±2.3) and between FBP 80kV and IR 70kV (18.9±1.8vs.19.9±2.6), p>0.10 (fig. 3).

Conclusion

The use of IR does facilitate lower kV settings, as IR shows same image quality compared to FBP at higher kV settings.