Example images of ultra low dose (ULD), HYPR-LR-post-processed ultra low dose (ULD+HYPR), low dose (LD) and HYPR-LR-post-processed low dose (HYPR+LD) brain perfusion CT of a 58-years old male patient with no pathology.

<p>The images are all reconstructed with the same slice thickness (5 mm) and presented with identical window settings.</p

Mean attenuation values in a corresponding 60 s time series of the ultra low dose (ULD), the HYPR-LR-post-processed ultra low dose (ULD+HYPR), the low dose (LD) and the HYPR-LR-post-processed low dose (HYPR+LD) images.

<p>Mean attenuation values in a corresponding 60 s time series of the ultra low dose (ULD), the HYPR-LR-post-processed ultra low dose (ULD+HYPR), the low dose (LD) and the HYPR-LR-post-processed low dose (HYPR+LD) images.</p

Subjective image quality scores and and quantitative attenuation measurements of LD and ULD and HYPR-LR post-processed BPCT data sets.

<p>Note: Subjective quality score are reported as mean values.</p

Low dose (LD, a), HYPR-LR-post-processed low dose (LD+HYPR, b), ultra low dose (ULD, c) and HYPR-LR-post-processed ultra low dose (ULD+HYPR, d) brain perfusion CT of a 75-year old male patient with a lung cancer metastasis adjacent to the right thalamus and chronic left frontal infarction.

<p>Last image of the 60 s time series (1) and the normalized cerebral blood flow (CBF, 2), mean transit time (MTT, 3), time to peak (TTP, 4), cerebral blood volume (CBV, 5) maps. The utilized software does not use reduced matrix reconstructions or spatial smoothing, the images are left noisy. The pathology is recognizable in a, b and d with excellent subjective image quality and low noise in b. No diagnosis possible in c.</p

Correlation of mean attenuation between original and post-processed data sets.

<p>Correlation of mean attenuation between original and post-processed data sets.</p

Ultra low dose (ULD), HYPR-LR-post-processed ultra low dose (ULD+HYPR), low dose (LD) and HYPR-LR-post-processed low dose (HYPR+LD) brain perfusion CT of a 35-years old patient with no pathology.

<p>This patient has slightly moved his head several times starting after 8 seconds of the data acquisition. As the HYPR-algorithm is using information of all time frames in the composite image for the calculation of the individual images, this resulted in an artifact visible in all HYPR-LR-post-processed images of this patient with a double contour of the skull and the brain on the right side and a frontal right hypodensity. The frontal right hypodensity was also visible in some non-post-processed images. The subjective image quality of the LD+HYPR image (rated 3) was still preferred to LD and ULD+HYPR (both rated 4). The ULD image was subjectively non-diagnostic (5). In the case of motion artifacts image registration might further improve image quality if used before the HYPR-LR algorithm is applied.</p

Example of manual measurement.

<p>Example of manual measurement of MPA diameter performed on axial reconstructions of the same magnetic resonance angiography data used for 3D segmentation. Manual measurements were performed for comparison with automated measurements.</p

Pulmonary artery volumes indexed to vessel length and corrected for BSA [μl/(cm length x m² BSA)].

<p>Pulmonary artery volumes indexed to vessel length and corrected for BSA [μl/(cm length x m² BSA)].</p

Example of 3D segmentation result.

<p>Representative automated 3D segmentation of central pulmonary arteries based on magnetic resonance angiography used for automated measurements. A color-coding is used to visualize pulmonary artery diameters of the 3D segmentation along the vessel course.</p

Bland-Altman plots for intra- and interobserver agreement.

<p>Bland-Altman plots show the differences between the two measurements performed by reader 1 (upper row) and the differences between measurements by the two readers (lower row) for automated 3D volume measurements (left), automated 3D mean diameter measurements (center) and manual diameter measurements (right) plotted against the means of the respective measurements. The straight line represents the mean difference, the dotted lines the limits of agreement. No systematic differences for repeated measurements could be observed. There is better agreement of automated 3D mean diameter measurements compared to manual diameter measurements.</p