Technical Innovations and Concepts in Coronary CT

Vogler, Nils; Meyer, Mathias; Henzler, Thomas

doi:10.1007/174_2016_95

Cited by 1 publication

(2 citation statements)

References 48 publications

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“…8 Time-resolved computed tomography (CT) datasets allow the calculation of various functional cardiac parameters including volumes, ejection fraction, myocardial mass, and wall motion. 9,10 CT may also offer a valuable alternative to echocardiography for the detection of conditions such as thrombosis, cannula malposition, and bleeding, and its adoption has been on the rise. 11 In energy integrated detector (EID) CT, the presence of metal in the LVAD commonly introduces image artifacts, such as beam hardening, blooming, noise, and scatter, which for instance explains the relatively low sensitivity and high specificity for detection of LVAD thrombus.…”

Section: Introductionmentioning

confidence: 99%

“…The metal of the LVAD severely limits the acoustic window resulting in an inability to visualize the entire outflow graft 7 and restricting assessment of thrombosis, bleeding, and infections 8 . Time‐resolved computed tomography (CT) datasets allow the calculation of various functional cardiac parameters including volumes, ejection fraction, myocardial mass, and wall motion 9,10 . CT may also offer a valuable alternative to echocardiography for the detection of conditions such as thrombosis, cannula malposition, and bleeding, and its adoption has been on the rise 11 .…”

Section: Introductionmentioning

confidence: 99%

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Optimization of photon counting CT for cardiac imaging in patients with left ventricular assist devices: An in‐depth assessment of metal artifacts

Konst,

Ohlsson,

Henriksson

et al. 2024

J Applied Clin Med Phys

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PurposePhoton counting CT (PCCT) holds promise for mitigating metal artifacts and can produce virtual mono‐energetic images (VMI), while maintaining temporal resolution, making it a valuable tool for characterizing the heart. This study aimed to evaluate and optimize PCCT for cardiac imaging in patients during left ventricular assistance device (LVAD) therapy by conducting an in‐depth objective assessment of metal artifacts and visual grading.MethodsVarious scan and reconstruction settings were tested on a phantom and further evaluated on a patient acquisition to identify the optimal protocol settings. The phantom comprised an empty thoracic cavity, supplemented with heart and lungs from a cadaveric lamb. The heart was implanted with an LVAD (HeartMate 3) and iodine contrast. Scans were performed on a PCCT (NAEOTOM Alpha, Siemens Healthcare). Metal artifacts were assessed by three objective methods: Hounsfield units (HU)/SD measurements (DiffHU and SDARTIFACT), Fourier analysis (AmplitudeLowFreq), and depicted LVAD volume in the images (BloomVol). Radiologists graded metal artifacts and the diagnostic interpretability in the LVAD lumen, cardiac tissue, lung tissue, and spinal cord using a 5‐point rating scale. Regression and correlation analysis were conducted to determine the assessment method most closely associated with acquisition and reconstruction parameters, as well as the objective method demonstrating the highest correlation with visual grading.ResultsDue to blooming artifacts, the LVAD volume fluctuated between 27.0 and 92.7 cm3. This variance was primarily influenced by kVp, kernel, keV, and iMAR (R2 = 0.989). Radiologists favored pacemaker iMAR, 3 mm slice thickness, and T3D keV and kernel Bv56f for minimal metal artifacts in cardiac tissue assessment, and 110 keV and Qr40f for lung tissue interpretation. The model adequacy for DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was 0.28, 0.76, 0.29, and 0.99 respectively for phantom data, and 0.95, 0.98, 1.00, and 0.99 for in‐vivo data. For in‐vivo data, the correlation between visual grading (VGSUM) and DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was −0.16, −0.01, −0.48, and −0.40 respectively.ConclusionWe found that optimal scan settings for LVAD imaging involved using 120 kVp and IQ level 80. Employing T3D with pacemaker iMAR, the sharpest allowed vascular kernel (Bv56f), and VMI at 110 keV with kernel Qr40 yields images suitable for cardiac imaging during LVAD‐therapy. Volumetric measurements of the LVAD for determination of the extent of blooming artifacts was shown to be the best objective method to assess metal artifacts.

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