Dual-contrast agent photon-counting computed tomography of the heart: initial experience

Abstract

To determine the feasibility of dual-contrast agent imaging of the heart using photon-counting detector (PCD) computed tomography (CT) to simultaneously assess both first-pass and late enhancement of the myocardium. An occlusion-reperfusion canine model of myocardial infarction was used. Gadolinium-based contrast was injected 10 min prior to PCD CT. Iodinated contrast was infused immediately prior to PCD CT, thus capturing late gadolinium enhancement as well as first-pass iodine enhancement. Gadolinium and iodine maps were calculated using a linear material decomposition technique and compared to single-energy (conventional) images. PCD images were compared to in vivo and ex vivo magnetic resonance imaging (MRI) and histology. For infarct versus remote myocardium, contrast-to-noise ratio (CNR) was maximal on late enhancement gadolinium maps (CNR 9.0 ± 0.8, 6.6 ± 0.7, and 0.4 ± 0.4, p < 0.001 for gadolinium maps, single-energy images, and iodine maps, respectively). For infarct versus blood pool, CNR was maximum for iodine maps (CNR 11.8 ± 1.3, 3.8 ± 1.0, and 1.3 ± 0.4, p < 0.001 for iodine maps, gadolinium maps, and single-energy images, respectively). Combined first-pass iodine and late gadolinium maps allowed quantitative separation of blood pool, scar, and remote myocardium. MRI and histology analysis confirmed accurate PCD CT delineation of scar. Simultaneous multi-contrast agent cardiac imaging is feasible with photon-counting detector CT. These initial proof-of-concept results may provide incentives to develop new k-edge contrast agents, to investigate possible interactions between multiple simultaneously administered contrast agents, and to ultimately bring them to clinical practice.

Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

“…With PCD‐CT, a series of energy‐bin images can be generated from a single data acquisition, with each energy‐bin image representing the photons detected within a user‐defined energy window. This allows PCD‐CT to measure the change in x‐ray attenuation due to the K‐edges present in materials such as gadolinium (Gd) and bismuth (Bi) …”

Photon-Counting CT of the Brain: In Vivo Human Results and Image-Quality Assessment

“…PCDs measure the number of detected x-ray photons (ie, photon count) and their photon energy. [6][7][8][9][10][11] These characteristics allow equal weighting of low-and high-energy photons and may therefore be useful for improving soft-tissue contrast in the brain. 8 In addition, the direct conversion and counting of individual photons provide a better estimate of the underlying photon statistics, which, in turn, may improve image quality by reducing image noise.…”

Cardiovascular imaging 2017 in the International Journal of Cardiovascular Imaging

“…Symons et al describe feasibility of dual-contrast agent imaging of the heart using photon-counting detector (PCD) computed tomography (CT) to simultaneously assess both first-pass and late enhancement of the myocardium [86]. An occlusion-reperfusion canine model of myocardial infarction was used.…”