Ranish Deedar Ali Khawaja MD, Presenter: Nothing to Disclose

Rachna Madan MD, Abstract Co-Author: 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

Michael Austin Blake MBBCh, Abstract Co-Author: Editor with royalties, Springer Science+Business Media Deutschland GmbH

Sanjay Saini MD, Abstract Co-Author: Nothing to Disclose

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

Atul Padole MD, Abstract Co-Author: Nothing to Disclose

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

Erin Angel PhD, Abstract Co-Author: Employee, Toshiba Corporation

To assess ultra-low dose (ULD) abdominal MDCT using a three-dimensional adaptive iterative reconstruction (AIDR-3D) & SafeCT, an image-based vendor-neutral iterative reconstruction (IR) compared with standard-dose imaging.

A total of 36 patients (mean age 66±12 years; M:F 19:17; mean weight 71±15 kg) gave informed consent for this prospective clinical study & underwent abdominal CT on 320 MDCT(AquillionONE, Toshiba Healthcare). Two consecutive image series were acquired in each patient: (i) standard-of-care (SD) CT [6mSv, mean CTDIvol 8 mGy ] and (ii) ULD-CT (0.9mSv, 2.5 mGy). Scan length of ULD-CT was half that of SD-CT (lung bases to mid-abdomen). SD-CT & ULD data were reconstructed with FBP, SafeCT(MedicVision Israel) & AIDR-3D  resulting in 360 image series. Two radiologists independently assessed subjective quality using a task-based evaluation to assess organ-based focal lesions & normal anatomical structures (when no lesions were present). Image noise was measured at homogenous liver parenchyma. Noise-spectral density plots were obtained. Student’s t-test and ANOVA  were used on SPSS v 22.0.

Mean dose reduction relative to SD CT was 75%. Radiologists identified 173 focal lesions with SD-FBP. Lesion detection for ULD-CT images was 79% (139/176; most lesion being missed in patients weighing ≥75kg 37% missed 50/79). ULD-FBP images were clinically inadequate for all abdominal structures. Mean subjective image quality score for ULD-IRT images was significantly higher in patients weighing <75kg (p<.01). For liver margins & parenchyma, ULD-AIDR3D & ULD-SafeCT images were significantly better than ULD-FBP images (p<0.01). Visualization of low-contrast hepatic & renal lesions was clinically adequate on both ULD-AIDR3D & ULD-SafeCT images compared to ULD-FBP (p<0.01). Mean liver image noise for ULD-AIDR3D was 17HU, significantly lower than SD-FBP (22, p=.009), ULD-FBP (60HU, p<.001) & ULD-SafeCT (26HU, p=.003). Although image quality of SD images were significantly better than ULD, lesion detection was deemed acceptable on ULD scans reconstructed with IR techniques (p<.01).

Iterative reconstruction techniques (such as 3-dimensional AIDR and SafeCT) show great potential for substantially reducing radiation dose of abdominal MDCT.

Abdominal MDCT is achievable at 2.5 mGy [~0.9mSv] using 3D-AIDR and image-based SafeCT without significant compromise in image quality at 75% dose reduction.

Khawaja, R, Madan, R, Singh, S, Blake, M, Saini, S, Kalra, M, Padole, A, Pourjabbar, S, Angel, E, Achieving Sub-milliSievert Radiation Dose: Prospective Randomized Clinical Study to Assess Ultra-low Dose Abdominal MDCT with a Three Dimensional Adaptive Iterative Reconstruction (AIDR) and Image-based Iterative Reconstruction (SafeCT).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004243.html