Browsing by Author "Kunze, Karl P."

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    3D joint T 1/T 1 ρ/T 2 mapping and water-fat imaging for contrast-agent free myocardial tissue characterization at 1.5T.
    (2025) Crabb, Michael G.; Kunze, Karl P.; Littlewood, Simon J.; Tripp, Donovan; Fotaki, Anastasia; Prieto Vásquez, Claudia; Botnar, René Michael
    PURPOSE: To develop a novel, free-breathing, 3D joint T 1 $$ {T}_1 $$ / T 1 ρ $$ {T}_{1\rho } $$ / T 2 $$ {T}_2 $$ mapping sequence with Dixon encoding to provide co-registered 3D T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ maps and water-fat volumes with isotropic spatial resolution in a single ≈ 7 $$ \approx 7 $$ min scan for comprehensive contrast-agent-free myocardial tissue characterization and simultaneous evaluation of the whole-heart anatomy. METHODS: An interleaving sequence over 5 heartbeats is proposed to provide T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ encoding, with 3D data acquired with Dixon gradient-echo readout and 2D image navigators to enable 100 % $$ 100\% $$ respiratory scan efficiency. Images were reconstructed with a non-rigid motion-corrected, low-rank patch-based reconstruction, and maps were generated through dictionary matching. The proposed sequence was compared against conventional 2D techniques in phantoms, 10 healthy subjects, and 1 patient. RESULTS: The proposed 3D T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ measurements showed excellent correlation with 2D reference measurements in phantoms. For healthy subjects, the mapping values of septal myocardial tissue were T 1 = 1060 ± 48 ms $$ {T}_1=1060\pm 48\kern0.2778em \mathrm{ms} $$ , T 1 ρ = 48 . 1 ± 3 . 9 ms $$ {T}_{1\rho }=48.1\pm 3.9\kern0.2778em \mathrm{ms} $$ , and T 2 = 44 . 2 ± 3 . 2 ms $$ {T}_2=44.2\pm 3.2\kern0.2778em \mathrm{ms} $$ for the proposed sequence, against T 1 = 959 ± 15 ms $$ {T}_1=959\pm 15\kern0.2778em \mathrm{ms} $$ , T 1 ρ = 56 . 4 ± 1 . 9 ms $$ {T}_{1\rho }=56.4\pm 1.9\kern0.2778em \mathrm{ms} $$ , and T 2 = 47 . 3 ± 1 . 5 ms $$ {T}_2=47.3\pm 1.5\kern0.2778em \mathrm{ms} $$ for 2D MOLLI, 2D T 1 ρ $$ {T}_{1\rho } $$ -prep bSSFP and 2D T 2 $$ {T}_2 $$ -prep bSSFP, respectively. Promising results were obtained when comparing the proposed mapping to 2D references in 1 patient with active myocarditis. CONCLUSION: The proposed approach enables simultaneous 3D whole-heart joint T 1 $$ {T}_1 $$ / T 1 ρ $$ {T}_{1\rho } $$ / T 2 $$ {T}_2 $$ mapping and water/fat imaging in ≈ $$ \approx $$ 7 min scan time, demonstrating good agreement with conventional mapping techniques in phantoms and healthy subjects and promising results in 1 patient with suspected cardiovascular disease.
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    3D whole-heart grey-blood late gadolinium enhancement cardiovascular magnetic resonance imaging
    (2021) Milotta, Giorgia; Munoz, Camila; Kunze, Karl P.; Neji, Radhouene; Figliozzi, Stefano; Chiribiri, Amedeo; Hajhosseiny, R.; Masci, Pier Giorgio; Prieto Vásquez, Claudia; Botnar, René Michael
    Abstract Purpose To develop a free-breathing whole-heart isotropic-resolution 3D late gadolinium enhancement (LGE) sequence with Dixon-encoding, which provides co-registered 3D grey-blood phase-sensitive inversion-recovery (PSIR) and complementary 3D fat volumes in a single scan of < 7 min. Methods A free-breathing 3D PSIR LGE sequence with dual-echo Dixon readout with a variable density Cartesian trajectory with acceleration factor of 3 is proposed. Image navigators are acquired to correct both inversion recovery (IR)-prepared and reference volumes for 2D translational respiratory motion, enabling motion compensated PSIR reconstruction with 100% respiratory scan efficiency. An intermediate PSIR reconstruction is performed between the in-phase echoes to estimate the signal polarity which is subsequently applied to the IR-prepared water volume to generate a water grey-blood PSIR image. The IR-prepared water volume is obtained using a water/fat separation algorithm from the corresponding dual-echo readout. The complementary fat-volume is obtained after water/fat separation of the reference volume. Ten patients (6 with myocardial scar) were scanned with the proposed water/fat grey-blood 3D PSIR LGE sequence at 1.5 T and compared to breath-held grey-blood 2D LGE sequence in terms of contrast ratio (CR), contrast-to-noise ratio (CNR), scar depiction, scar transmurality, scar mass and image quality. Results Comparable CRs (p = 0.98, 0.40 and 0.83) and CNRs (p = 0.29, 0.40 and 0.26) for blood-myocardium, scar-myocardium and scar-blood respectively were obtained with the proposed free-breathing 3D water/fat LGE and 2D clinical LGE scan. Excellent agreement for scar detection, scar transmurality, scar mass (bias = 0.29%) and image quality scores (from 1: non-diagnostic to 4: excellent) of 3.8 ± 0.42 and 3.6 ± 0.69 (p > 0.99) were obtained with the 2D and 3D PSIR LGE approaches with comparable total acquisition time (p = 0.29). Similar agreement in intra and inter-observer variability were obtained for the 2D and 3D acquisition respectively. Conclusion The proposed approach enabled the acquisition of free-breathing motion-compensated isotropic-resolution 3D grey-blood PSIR LGE and fat volumes. The proposed approach showed good agreement with conventional 2D LGE in terms of CR, scar depiction and scan time, while enabling free-breathing acquisition, whole-heart coverage, reformatting in arbitrary views and visualization of both water and fat information.
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    High-resolution non-contrast free-breathing coronary cardiovascular magnetic resonance ngiography for detection of coronary artery disease: validation against invasive coronary angiography
    (2022) Nazir, Muhummad Sohaib; Bustin, Aurelien; Hajhosseiny, Reza; Yazdani, Momina; Ryan, Matthew; Vergani, Vittoria; Neji, Radhouene; Kunze, Karl P.; Nicol, Edward; Masci, Pier Giorgio; Perera, Divaka; Plein, Sven; Chiribiri, Amedeo; Botnar, Rene; Prieto, Claudia
    Background: Coronary artery disease (CAD) is the single most common cause of death worldwide. Recent technological developments with coronary cardiovascular magnetic resonance angiography (CCMRA) allow high-resolution free-breathing imaging of the coronary arteries at submillimeter resolution without contrast in a predictable scan time of similar to 10 min. The objective of this study was to determine the diagnostic accuracy of high-resolution CCMRA for CAD detection against the gold standard of invasive coronary angiography (ICA).
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    Highly efficient image navigator based 3D whole-heart cardiac MRA at 0.55T
    (2024) Castillo-Passi, Carlos; Kunze, Karl P.; Crabb, Michael G.; Munoz, Camila; Fotaki, Anastasia; Neji, Radhouene; Irarrazaval, Pablo; Prieto, Claudia; Botnar, Rene M.
    PurposeTo develop and evaluate a highly efficient free-breathing and contrast-agent-free three-dimensional (3D) whole-heart Cardiac Magnetic Resonance Angiography (CMRA) sequence at 0.55T.MethodsFree-breathing whole-heart CMRA has been previously proposed at 1.5 and 3T. Direct application of this sequence to 0.55T is not possible due to changes in the magnetic properties of the tissues. To enable free-breathing CMRA at 0.55T, pulse sequence design and acquisition parameters of a previously proposed whole-heart CMRA framework are optimized via Bloch simulations. Image navigators (iNAVs) are used to enable nonrigid respiratory motion-correction and 100% respiratory scan efficiency. Patch-based low-rank denoising is employed to accelerate the scan and account for the reduced signal-to-noise ratio at 0.55T. The proposed approach was evaluated on 11 healthy subjects. Image quality was assessed by a clinical expert (1: poor to 5: excellent) for all intrapericardiac structures. Quantitative evaluation was performed by assessing the vessel sharpness of the proximal right coronary artery (RCA).ResultsOptimization resulted in an imaging flip angle of 110 degrees$$ 11{0}<^>{\circ } $$, fat saturation flip angle of 180 degrees$$ 18{0}<^>{\circ } $$, and six k-space lines for iNAV encoding. The relevant cardiac structures and main coronary arteries were visible in all subjects, with excellent image quality (mean 4.9/5.0$$ 4.9/5.0 $$) and minimal artifacts (mean 4.9/5.0$$ 4.9/5.0 $$), with RCA vessel sharpness (50.3%+/- 9.8%$$ 50.3\%\pm 9.8\% $$) comparable to previous studies at 1.5T.ConclusionThe proposed approach enables 3D whole-heart CMRA at 0.55T in a 6-min scan (5.9 +/- 0.7 min$$ 5.9\pm 0.7\;\min $$), providing excellent image quality, minimal artifacts, and comparable vessel sharpness to previous 1.5T studies. Future work will include the evaluation of the proposed approach in patients with cardiovascular disease.
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    Isotropic, high-resolution, whole-chest inversion recovery contrast-enhanced magnetic resonance angiography in under 4.5 min using image-based navigator fluoro trigger
    (2025) Craft, Jason; Parikh, Roosha; Cheng, Josh Y.; Diaz, Nancy; Kunze, Karl P.; Schmidt, Michaela; Neji, Radhouene; Leung, Amanda; Weber, Suzanne; Weber, Jonathan; Carter, Timothy; Biso, Sylvia; Yamashita, Ann-Marie; Wolff, Eric H.; Prieto Vásquez, Claudia Del Carmen; Botnar, Rene Michael
    BACKGROUND: Serial assessment of the thoracic aorta with magnetic resonance angiography (MRA) is desirable due to 3D volumetric dataset, high spatial resolution, and lack of ionizing radiation. Electrocardiogram (ECG) gated, contrast-enhanced (CE), inversion recovery gradient echo MRA is efficient and historically provides low artifact burden, but the window for imaging with weak albumin binding extracellular gadolinium based contrast agents is small. Our purpose was to acquire whole-chest gated CE-MRA with 1.2 mm 3 resolution using image-based navigator (iNAV) for motion correction/contrast monitoring, and variable density sampling in 4-5 min. Image quality and vessel diameter reproducibility are assessed against time resolved MRA (TR-MRA). METHODS: iNAV CE-MRA and TR-MRA were obtained prospectively in 40 patients and reviewed by 3 blinded cardiologists for vessel diameter and image quality rated on a four point scale: (1) non-diagnostic; (2) poor-significant blurring; (3) good-mild blurring; and (4) excellent. Reproducibility and image quality were evaluated using the concordance correlation statistic and Cohen's kappa with mean differences evaluated using paired t-tests and repeat-measures ANOVA. RESULTS: iNAV CE-MRA scan time was 4.2 ± 0.7 min. iNAV CE-MRA quality score was higher ( p  
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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.