title: Optimized radiographic spectra for small animal digital subtraction angiography.
abstract: The increasing use of small animals in basic research has spurred interest in new imaging methodologies. Digital subtraction angiography (DSA) offers a particularly appealing approach to functional imaging in the small animal. This study examines the optimal x-ray, molybdenum (Mo) or tungsten (W) target sources, and technique to produce the highest quality small animal functional subtraction angiograms in terms of contrast and signal-difference-to-noise ratio squared (SdNR2). Two limiting conditions were considered-normalization with respect to dose and normalization against tube loading. Image contrast and SdNR2 were simulated using an established x-ray model. DSA images of live rats were taken at two representative tube potentials for the W and Mo sources. Results show that for small animal DSA, the Mo source provides better contrast. However, with digital detectors, SdNR2 is the more relevant figure of merit. The W source operated at kVps >60 achieved a higher SdNR2. The highest SdNR2 was obtained at voltages above 90 kVp. However, operation at the higher potential results in significantly greater dose and tube load and reduced contrast quantization. A reasonable tradeoff can be achieved at tube potentials at the beginning of the performance plateau, around 70 kVp, where the relative gain in SdNR2 is the greatest.
authors.affiliation: Center for In Vivo Microscopy, Box 3302, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Ming De
authors.initials: MD
authors.lastname: Lin
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
authors.forename: Cristian T
authors.initials: CT
authors.lastname: Badea
authors.forename: Terry T
authors.initials: TT
authors.lastname: Yoshizumi
authors.forename: G Allan
authors.initials: GA
authors.lastname: Johnson
mesh_terms: D000465:Algorithms; D015901:Angiography, Digital Subtraction / Q000295:instrumentation / Q000379:methods* / Q000662:veterinary*; D000818:Animals; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation / Q000379:methods* / Q000662:veterinary*