An acquisition and image reconstruction scheme for reduced x-ray exposure dynamic 3D CTA

We present Computed Tomography (CT) acquisition and reconstruction schemes for low-dose neuro-angiography based on the method of HighlY constrained back PRojection (HYPR). Simulated and experimental low X-ray radiation dose scans were prepared using the techniques of interleaved view angle under-sampling and tube current reduction. Dynamic CT Angiograms (CTAs) were produced for both standard and low dose images sets. The spatial correlation coefficient, r, between the two reconstruction approaches was determined for each time frame and the SNR and CNR values in arterial ROIs were calculated. The undersampled HYPR reconstructions produced r values of > 0.95 at undersampling and dose reduction factors-of 10 and SNR and CNR were more than doubled using HYPR techniques at a tube current of 25 mA. HYPR approaches to contrast enhanced neuro-imaging provide not only volumetric brain hemodynamics but also the ability to produce high quality maps of standard perfusion parameters. The synergy of volumetric hemodynamics and assessment of tissue function provides the medical imaging community with high quality diagnostic information at a fraction of the radiation dose in a single contrast-enhanced scan.