Improved image quality with simultaneously reduced radiation exposure: Knowledge-based iterative model reconstruction algorithms for coronary CT angiography in a clinical setting.
BACKGROUND
The aim of this study was to assess the potential for radiation dose reduction using knowledge-based iterative model reconstruction (K-IMR) algorithms in combination with ultra-low dose body mass index (BMI)-adapted protocols in coronary CT angiography (coronary CTA).


METHODS
Forty patients undergoing clinically indicated coronary CTA were randomly assigned to two groups with BMI-adapted (I: <25.0 kg/m2, II: <28.0 kg/m2, III: <30.0 kg/m2, IV: ≥30.0 kg/m2) low dose (LD, I: 100kVp/75 mAs, II: 100kVp/100 mAs, III: 100kVp/150 mAs, IV: 120kVp/150 mAs, n = 20) or ultra-low dose (ULD, I: 100kVp/50 mAs, II: 100kVp/75 mAs, III: 100kVp/100 mAs, IV: 120kVp/100 mAs, n = 20) protocols. Prospectively-triggered coronary CTA was performed using a 256-MDCT with the lowest reasonable scan length. Images were generated with filtered back projection (FBP), a noise-reducing hybrid iterative algorithm (iD, levels 2/5) and K-IMR using cardiac routine (CR) and cardiac sharp settings, levels 1-3.


RESULTS
Groups were comparable regarding anthropometric parameters, heart rate, and scan length. The use of ULD protocols resulted in a significant reduction of radiation exposure (0.7 (0.6-0.9) mSv vs. 1.1 (0.9-1.7) mSv; p < 0.02). Image quality was significantly better in the ULD group using K-IMR CR 1 compared to FBP, iD 2 and iD 5 in the LD group, resulting in fewer non-diagnostic coronary segments (2.4% vs. 11.6%, 9.2% and 6.1%; p < 0.05).


CONCLUSIONS
The combination of K-IMR with BMI-adapted ULD protocols results in significant radiation dose savings while simultaneously improving image quality compared to LD protocols with FBP or hybrid iterative algorithms. Therefore, K-IMR allows for coronary CTA examinations with high diagnostic value and very low radiation exposure in clinical routine.
University of Heidelberg, Department of Cardiology, Angiology and Pneumology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany. Electronic address: florian.andre@med.uni-heidelberg.de.
Florian
F
André
University of Heidelberg, Department of Cardiology, Angiology and Pneumology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany.
Philipp
P
Fortner
CT Clinical Science, Philips Healthcare, c595 Miner Road, Cleveland, OH 44143, USA.
Mani
M
Vembar
CT Clinical Science, Philips Healthcare, Luebeckertordamm 5, Hamburg, 20099, Germany.
Dirk
D
Mueller
University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany.
Wolfram
W
Stiller
University of Heidelberg, Department of Cardiology, Angiology and Pneumology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany; Das Radiologische Zentrum - Radiology Center, Sinsheim-Eberbach-Erbach-Walldorf-Heidelberg, Rohrbacher Straße 149, Heidelberg, 69126, Germany.
Sebastian J
SJ
Buss
University of Heidelberg, Department of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany.
Hans-Ulrich
HU
Kauczor
University of Heidelberg, Department of Cardiology, Angiology and Pneumology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany.
Hugo A
HA
Katus
University of Heidelberg, Department of Cardiology, Angiology and Pneumology, Im Neuenheimer Feld 410, Heidelberg, 69120, Germany.
Grigorios
G
Korosoglou
D000368:Aged; D000465:Algorithms; D015992:Body Mass Index; D000072226:Computed Tomography Angiography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D005858:Germany; D006801:Humans; D051188:Knowledge Bases; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000009:adverse effects / Q000517:prevention & control*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio
Coronary CT angiography; Coronary artery disease; Image reconstruction; Iterative reconstruction; Knowledge-based reconstruction; Multidetector computed tomography; Radiation exposure