Multi-detector CT of the chest: influence of dose onto quantitative evaluation of severe emphysema: a simulation study.
OBJECTIVE
Quantitative evaluation of the lung parenchyma might be impaired or unreliable by use of reduced-dose CT protocols. Aim of the study was to define the threshold where reduced dose has significant impact on quantitative emphysema parameters.


METHODS
Thirty patients with severe centrilobular emphysema underwent multidetector computed tomography (120 kV, 150 mAs). Original CT raw data were simulated using 10 mAs settings (10-100 SIMmAs). Quantitative analysis provided lung volume, emphysema volume, emphysema index, mean lung density, and 4 emphysema volume classes. Simulated low-dose results were compared with original acquisition.


RESULTS
Emphysema index showed no clinical relevant variation down to 30 SIMmAs. The large emphysema volume class was significantly different below 50 SIMmAs. The intermediate and small classes showed an overproportional variation below 50 SIMmAs.


CONCLUSIONS
Dose reduction down to 30 SIMmAs is possible for clinical routine. Settings below 50 SIMmAs significantly alter the in-detailed 3-dimensional emphysema quantification.
Zaporozhan
Julia
J
Department of Radiology (E 010), German Cancer Research Center, and Department of Pediatric Radiology, Ruprecht-Karls-University, Heidelberg, Germany. juliazapo@web.de
Ley
Sebastian
S
Weinheimer
Oliver
O
Eberhardt
Ralf
R
Tsakiris
Ioannis
I
Noshi
Yasuhiro
Y
Herth
Felix
F
Kauczor
Hans-Ulrich
HU
D000328:Adult; D000368:Aged; D004646:Emphysema / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*