We exploited 4-dimensional flow magnetic resonance imaging (4D Flow), combined with two in vitro setups for the evaluation and estimation of paravalvular leaks (PVLs) associated with transcatheter aortic valve implantation (TAVI). 4D Flow analysis was performed on a Portico™ TAVI (Abbott Laboratories, Irvine, USA). The valve was implanted in an anatomically realistic silicone phantom of left ventricle, aortic root, and ascending aorta. In the two different MRI-compatible setups, the systolic peak was simulated through continuous anterograde flow, the diastolic phase through continuous retrograde flow, and the entire cardiac cycle through pulsatile flow. Acquisitions were processed using a Phyton code to obtain 4D Flow. Flow rates were calculated, velocity patterns in ascending aorta were visualized, and PVLs were visualized and estimated. For the PVLs assessment with continuous flow, the results obtained by 4D flow were compared with the ground truth flowmeter measurements, obtaining a similar classification of PVLs according to the 5-grading scale. The results acquired with the pulsatile setup were validated against echo color doppler imaging, the current gold standard for the detection of PVLs, also in this case the classification was confirmed. The efficacy of the noninvasive 4D Flow MRI protocol for the detection of PVLs and their estimation could overcome the main limitations of the techniques currently used in clinical applications, as well as represent a useful tool in the process of evaluating the performances of TAVI in vitro.
É stata utilizzata la tecnica di MRI 4D Flow in combinazione con due setup in vitro per la valutazione e la stima dei rigurgiti paravalvolari (PVLs) associati all'impianto di una valvola aortica transcatetere (TAVI). L'analisi tramite 4D Flow è stata eseguita su una Portico™ TAVI (Abbott Laboratories, Irvine, USA). La valvola è stata impiantata in un phantom anatomicamente realistico di ventricolo sinistro, radice aortica ed aorta ascendente in silicone. Nei due differenti setup compatibili con risonanza magnetica sono stati simulati: con il flusso continuo anterogrado, il picco sistolico; con il flusso continuo retrogrado, la fase diastolica e con il flusso pulsatile, l'intero ciclo cardiaco. Le acquisizioni sono state processate tramite un codice Phyton per l'ottenimento del 4D Flow. Sono state quindi calcolate le portate, è stato visualizzato l'andamento delle velocità in aorta ascendente e sono stati visualizzati e stimati i PVLs. La tecnica di 4D Flow ha permesso la visualizzazione tridimensionale dell'andamento del flusso in aorta ascendente e nel ventricolo sinistro. Per la valutazione dei PVLs nel caso di flusso continuo, i risultati ottenuti tramite 4D flow sono stati confrontati con le misure effettuate mediante flussimetro ottenendo un'analoga classificazione dei PVLs secondo la scala a 5-gradi proposta da Pibarot et al.. Per il setup pulsatile, i risultati sono stati invece validati tramite la tecnica di eco color doppler, attuale gold standard per l'individuazione di PVLs ed anche in questo caso la classificazione è stata confermata. L'efficacia del protocollo di MRI 4D Flow non invasivo per l'individuazione dei PVLs e per la loro stima potrebbe superare le principali limitazioni delle tecniche attualmente in uso in clinica, oltre a rappresentare un utile strumento nel processo di valutazione dell'efficacia della TAVI in vitro.
Stima del rigurgito paravalvolare associato a impianti TAVI mediante l'uso di MRI 4D Flow e di phantom della radice aortica
Panfili, Sebastiano;Sella Bart, Eleonora
2019/2020
Abstract
We exploited 4-dimensional flow magnetic resonance imaging (4D Flow), combined with two in vitro setups for the evaluation and estimation of paravalvular leaks (PVLs) associated with transcatheter aortic valve implantation (TAVI). 4D Flow analysis was performed on a Portico™ TAVI (Abbott Laboratories, Irvine, USA). The valve was implanted in an anatomically realistic silicone phantom of left ventricle, aortic root, and ascending aorta. In the two different MRI-compatible setups, the systolic peak was simulated through continuous anterograde flow, the diastolic phase through continuous retrograde flow, and the entire cardiac cycle through pulsatile flow. Acquisitions were processed using a Phyton code to obtain 4D Flow. Flow rates were calculated, velocity patterns in ascending aorta were visualized, and PVLs were visualized and estimated. For the PVLs assessment with continuous flow, the results obtained by 4D flow were compared with the ground truth flowmeter measurements, obtaining a similar classification of PVLs according to the 5-grading scale. The results acquired with the pulsatile setup were validated against echo color doppler imaging, the current gold standard for the detection of PVLs, also in this case the classification was confirmed. The efficacy of the noninvasive 4D Flow MRI protocol for the detection of PVLs and their estimation could overcome the main limitations of the techniques currently used in clinical applications, as well as represent a useful tool in the process of evaluating the performances of TAVI in vitro.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/173446