Ultra-High-Resolution and K-Edge Imaging of Prosthetic Heart Valves With Spectral Photon-Counting CT: A Phantom Study.

Invest Radiol

From the University of Lyon, INSA-Lyon, University Claude Bernard Lyon 1, Villeurbanne, France (S.B., F.D.); Department of Cardiovascular and Thoracic Radiology, Louis Pradel Hospital, Hospices Civils de Lyon, Bron, France (S.B., C.M., S.S.-M., L.B., P.D.); University Lyon, INSA-Lyon, University Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, Villeurbanne, France (H.L., S.S.-M., L.B., P.D.); Philips Healthcare, Suresnes, France (M.V.); Department of Cardiology, Louis Pradel Hospital, Hospices Civils de Lyon, Bron, France (F.D.); Department of Radiology and Nuclear Medicine, Erasmus Medical Center, Rotterdam, the Netherlands (R.B.); and Department of Cardiac Surgery, Louis Pradel Hospital, Hospices Civils de Lyon, Bron, France (M.P.).

Published: August 2024

AI Article Synopsis

  • The study investigates the effectiveness of cardiac computed tomography (CT) in detecting complications of prosthetic heart valves (PHVs), focusing on advancements with photon-counting detectors (PCDs) compared to dual-energy dual-layer CT (DEDL-CT).
  • Researchers used a thoracic phantom with various PHVs and lesions to perform scans, analyzing image quality and artifacts such as blooming and streaks.
  • Results indicate that PCD-CT provides improved image clarity, with thinner metallic structures and significantly reduced artifacts compared to DEDL-CT.

Article Abstract

Background And Purpose: The contribution of cardiac computed tomography (CT) for the detection and characterization of prosthetic heart valve (PHV) complications is still limited due mainly to artifacts. Computed tomography systems equipped with photon-counting detectors (PCDs) have the potential to overcome these limitations. Therefore, the aim of the study was to compare image quality of PHV with PCD-CT and dual-energy dual-layer CT (DEDL-CT).

Materials And Methods: Two metallic and 3 biological PHVs were placed in a tube containing diluted iodinated contrast inside a thoracic phantom and scanned repeatedly at different angles on a DEDL-CT and PCD-CT. Two small lesions (~2 mm thickness; containing muscle and fat, respectively) were attached to the structure of 4 valves, placed inside the thoracic phantom, with and without an extension ring, and scanned again. Acquisition parameters were matched for the 2 CT systems and used for all scans. Metallic valves were scanned again with parameters adapted for tungsten K-edge imaging. For all valves, different metallic parts were measured on conventional images to assess their thickness and blooming artifacts. In addition, 6 parallelepipeds per metallic valve were drawn, and all voxels with density <3 times the standard deviation of the contrast media were recorded as an estimate of streak artifacts. For subjective analysis, 3 expert readers assessed conventional images of the valves, with and without lesions, and tungsten K-edge images. Conspicuity and sharpness of the different parts of the valve, the lesions, metallic, and blooming artifacts were scored on a 4-point scale. Measurements and scores were compared with the paired t test or Wilcoxon test.

Results: The objective analysis showed that, with PCD-CT, valvular metallic structures were thinner and presented less blooming artifacts. Metallic artifacts were also reduced with PCD-CT (11 [interquartile (IQ) = 6] vs 40 [IQ = 13] % of voxels). Subjective analysis allowed noticing that some structures were visible or clearly visible only with PCD-CT. In addition, PCD-CT yielded better scores for the conspicuity and for the sharpness of all structures (all P s < 0.006), except for the conspicuity of the leaflets of the mechanical valves, which were well visible with either technique (4 [IQ = 3] for both). Both blooming and streak artifacts were reduced with PCD-CT ( P ≤ 0.01). Overall, the use of PCD-CT resulted in better conspicuity and sharpness of the lesions compared with DEDL-CT (both P s < 0.02). In addition, only with PCD-CT some differences between the 2 lesions were detectable. Adding the extension ring resulted in reduced conspicuity and sharpness with DEDL-CT ( P = 0.04 and P = 0.02, respectively) and only in reduced sharpness with PCD-CT ( P = 0.04). Tungsten K-edge imaging allowed for the visualization of the only dense structure containing it, the leaflets, and it resulted in images judged having less blooming and metallic artifacts as compared with conventional PCD-CT images ( P < 0.01).

Conclusions: With PCD-CT, objective and subjective image quality of metallic and biological PHVs is improved compared with DEDL-CT. Notwithstanding the improvements in image quality, millimetric lesions attached to the structure of the valves remain a challenge for PCD-CT. Tungsten K-edge imaging allows for even further reduction of artifacts.

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Source
http://dx.doi.org/10.1097/RLI.0000000000001068DOI Listing

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