Browsing by Author "Reader, Andrew J."

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    Motion-corrected simultaneous cardiac positron emission tomography and coronary MR angiography with high acquisition efficiency
    (2018) Munoz, Camila; Neji, Radhouene; Cruz, Gastão; Mallia, Andrew; Jeljeli, Sami; Reader, Andrew J.; Botnar, René Michael; Prieto Vásquez, Claudia
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    MRI-Guided Motion-Corrected PET Image Reconstruction for Cardiac PET/MRI
    (SOC NUCLEAR MEDICINE INC, 2021) Munoz, Camila; Ellis, Sam; Nekolla, Stephan G.; Kunze, Karl P.; Vitadello, Teresa; Neji, Radhouene; Botnar, Rene M.; Schnabel, Julia A.; Reader, Andrew J.; Prieto, Claudia
    Simultaneous PET/MRI has shown potential for the comprehensive assessment of myocardial health from a single examination. Furthermore, MRI-derived respiratory motion information, when incorporated into the PET image reconstruction, has been shown to improve PET image quality. Separately, MRI-based anatomically guided PET image reconstruction has been shown to effectively denoise images, but this denoising has so far been demonstrated mainly in brain imaging. To date, the combined benefits of motion compensation and anatomic guidance have not been demonstrated for myocardial PET/MRI. This work addressed this lack by proposing a single cardiac PET/MRI image reconstruction framework that fully utilizes MRI-derived information to allow both motion compensation and anatomic guidance within the reconstruction. Methods: Fifteen patients underwent an F-18-FDG cardiac PET/MRI scan with a previously introduced acquisition framework. The MRI data processing and image reconstruction pipeline produces respiratory motion fields and a high-resolution respiratory motion-corrected MR image with good tissue contrast. This MRI-derived information was then included in a respiratory motion-corrected, cardiac-gated, anatomically guided image reconstruction of the simultaneously acquired PET data. Reconstructions were evaluated by measuring myocardial contrast and noise and were compared with images from several comparative intermediate methods using the components of the proposed framework separately. Results: Including respiratory motion correction, cardiac gating, and anatomic guidance significantly increased contrast. In particular, myocardiumto-blood pool contrast increased by 143% on average (P < 0.0001), compared with conventional uncorrected, non-guided PET images. Furthermore, anatomic guidance significantly reduced image noise, by 16.1%, compared with nonguided image reconstruction (P < 0.0001). Conclusion: The proposed framework for MRI-derived motion compensation and anatomic guidance of cardiac PET data significantly improved image quality compared with alternative reconstruction methods. Each component of the reconstruction pipeline had a positive impact on the final image quality. These improvements have the potential to improve clinical interpretability and diagnosis based on cardiac PET/MR images.
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    Non-rigid motion-compensated 3D whole-heart T2 mapping in a hybrid 3T PET-MR system
    (2024) Schneider, Alina; Munoz, Camila; Hua, Alina; Ellis, Sam; Jeljeli, Sami; Kunze, Karl P.; Neji, Radhouene; Reader, Andrew J.; Reyes, Eliana; Ismail, Tevfik F.; Botnar, Rene M.; Prieto, Claudia
    Purpose: Simultaneous PET-MRI improves inflammatory cardiac disease diagnosis. However, challenges persist in respiratory motion and mis-registration between free-breathing 3D PET and 2D breath-held MR images. We propose a free-breathing non-rigid motion-compensated 3D T-2-mapping sequence enabling whole-heart myocardial tissue characterization in a hybrid 3T PET-MR system and provides non-rigid respiratory motion fields to correct also simultaneously acquired PET data.Methods: Free-breathing 3D whole-heart T-2-mapping was implemented on a hybrid 3T PET-MRI system. Three datasets were acquired with different T-2-preparation modules (0, 28, 55 ms) using 3-fold under sampled variable-density Cartesian trajectory. Respiratory motion was estimated via virtual 3D image navigators, enabling multi-contrast non-rigid motion-corrected MR reconstruction. T-2-maps were computed using dictionary-matching. Approach was tested in phantom, 8 healthy subjects, 14 MR only and 2 PET-MR patients with suspected cardiac disease and compared with spin echo reference (phantom) and clinical 2D T-2-mapping (in-vivo).Results: Phantom results show a high correlation (R-2 = 0.996) between proposed approach and gold standard 2D T-2 mapping. In-vivo 3D T-2-mapping average values in healthy subjects (39.0 +/- 1.4 ms) and patients (healthy tissue) (39.1 +/- 1.4 ms) agree with conventional 2D T-2-mapping (healthy = 38.6 +/- 1.2 ms, patients = 40.3 +/- 1.7 ms). Bland-Altman analysis reveals bias of 1.8 ms and 95% limits of agreement (LOA) of -2.4-6 ms for healthy subjects, and bias of 1.3 ms and 95% LOA of -1.9 to 4.6 ms for patients.Conclusion: Validated efficient 3D whole-heart T-2-mapping at hybrid 3T PET-MRI provides myocardial inflammation characterization and non-rigid respiratory motion fields for simultaneous PET data correction. Comparable T-2 values were achieved with both 3D and 2D methods. Improved image quality was observed in the PET images after MR-based motion correction.