Simultaneous ultra-high resolution multi-energy cardiac imaging in a dual-source photon counting detector CT system.

Abstract

Objectives: To assess quantitative and qualitative image characteristics in phantoms and patients using a simultaneous ultra-high resolution (UHR) and multi-energy (ME) dual-source cardiac scan mode in a photon counting detector (PCD) CT scanner.

Methods: UHR-ME cardiac scans were performed to determine the spatial resolution and multi-energy performance. UHR reconstructions were completed to measure transverse and axial spatial resolution in terms of modulation transfer function (MTF) and slice sensitivity profile (SSP). Virtual monoenergetic images (VMIs), virtual non-contrast (VNC) images, and iodine concentration images were created using moderately sharp reconstruction kernels to assess ME performance. With IRB approval, coronary CT angiograms were acquired in 19 patients using the UHR-ME mode, from which iodine contrast-to-noise ratio (CNR) was measured. Various ME post-processing tasks were performed to show the utility of the spectral capabilities.

Results: VMIs showed a mean CT number error of 5.9%, while iodine accuracy was 0.75 mg/cc (root-mean-square-error). Spatial resolution matched well with a standard UHR mode. Patient images showed a trend of higher CNR at lower keV, while higher keV images showed decreased calcium blooming. ME techniques to separate iodine and calcium were used successfully.

Conclusions: The combination of UHR-ME cardiac mode retains UHR image quality while providing flexibility for ME post-processing.

Advances in knowledge: Cardiac UHR-ME scanning offers simultaneous ultra-high-resolution and ME imaging without loss of spatial or temporal resolution or quantitative accuracy.