Qingguo Wang, Presenter: Nothing to Disclose

To evaluate the impact of kV assist associated with adaptive statistical iterative reconstruction based on body mass index (BMI) on dose and image quality of CT angiography (CTA) for upper abdomen. 

This study included 46 patients who underwent CT angiography for upper abdomen using a 64-row CT scanner (GE Discovery CT750 HD). Patients were divided into two groups using and not using kV assist technique. Group A (n=23, BMI: 20.72±2.37) and group B (n=23, BMI: 22.31±1.82) underwent CT scan with standard tube kVp (120kVp) and low tube kVp (≤100kVp) recommended by kV assist. Data of Group B were reprocessed with a fixed blending level (50% and 0% respectively) of adaptive statistical iterative reconstruction (ASiR) for each image set. The baseline was 120 kVp, noise index (NI) =12.0(5mm). The CT value of abdominal fat layer, aorta (AR), superior mesenteric artery (SMA) were measured. The contrast noise ratio (CNR) and signal noise ratio(SNR) of AR and SMA were calculated respectively. The CT dose index volume (CTDIvol) of each patient were recorded. The dose length produce (DLP) was recorded and effective radiation dose was calculated.

The mean CTDIvol and effective radiation dose in group B (6.06 ±2.80mGy, 2.31 ±1.06mSv) were significantly lower than group A (9.26±4.69mGy, 3.81 ±2.31mSv) (p＜0.05). The mean CT values of AR and SMA in group A(219.08±45.93Hu, 217.09±44.90Hu) were lower than group B(50% ASiR)(276.00±111.32Hu, 269.82±104.32Hu) (p＜0.05). The mean CT values of AR and SMA in group B (0% ASiR) (276.32±111.25Hu, 264.10±101.67Hu) had no significant difference with those in group B (50% ASiR) (276.00±111.32Hu, 269.82±104.32Hu) (p>0.05). The SD values of subcutaneous fat in group A (8.17±1.49) was lower than group B(50% ASiR) (9.57±1.59) (p＜0.01). The CNRs of AR and SMA (50.05±15.40,48.53±14.16) in group B (50% ASiR) were higher than in group A (35.15±8.85,18.99±3.75) (p＜0.05). The SNRs of AR and SMA (34.62±13.82,33.11±12.48) in group B (50% ASiR) were higher than in group A (23.72±7.40,23.54±7.34) (p＜0.05).

KV assist can recommend optimal scan protocol and approximate 39% radiation dose reduction can be reached without degradation of image quality. 

KV assist helps to improve patient care through personalized protocols and simplify scan technique optimization. There is a potential to use significantly less radiation dose without image quality loss.

Wang, Q, Application of kV Assist Associated with Adaptive Statistical Iterative Reconstruction (ASiR) in Upper Abdominal CT Angiography.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045666.html