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Cardiovascular system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Intravascular ultrasound (IVUS) (Fig. 9.16d) is a technique for examining the inside of a blood vessel using a tiny ultrasound transducer that is passed through the lumen of a vessel, often as part of minimally-invasive heart surgery. This plays an important role before and during interventional procedures, in providing information on the type and extent of disease, enabling the clinician to select the most appropriate interventional procedure. Unlike OCT, which may also be performed during angiography, IVUS enables visualisation of the structures beyond the lumen and the visible wall of the vessel.
Technical Advances and Clinical Perspectives in Coronary MR Imaging
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Giulia Ginami, Imran Rashid, René M. Botnar, Claudia Prieto
Additionally, it has been shown that lipid-lowering therapies using statins result in a reduction of the local progression of coronary atherosclerosis quantified by the plaque burden [82]. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) provide high-resolution images of coronary plaque, but they are invasive and thus not suitable for screening or follow-up. Black-blood coronary MRI [83, 84] allows for high contrast visualization of the coronary vessel wall; this is achieved by suppressing the signal from the flowing blood and by enhancing that of the static tissues. As such, black-blood coronary MRI is a potential candidate for non-invasive investigation of the atherosclerotic processes occurring in the vessel wall and for the assessment of coronary plaque burden. The first in vivo studies on plaque characterization were performed by exploiting the double inversion recovery (DIR) technique [85, 86]; DIR is a flow-dependent technique that utilizes two separate inversion pulses to (1) non-selectively invert the signal from static tissues and blood within the imaging volume and (2) selectively re-invert the signal of static tissues within a target 2D slice. At the moment of data collection, and within the target slice, static tissues will have re-inverted positive magnetization while in-flowing blood will have approximately nulled magnetization (Figures 15.12 and 15.13). Initial clinical studies assessed the presence of plaques in carotid arteries [87–89]. Imaging the coronary vessel wall is more challenging since, as anticipated, the coronaries are small in diameter, exhibit a complex geometry, and are subject to cardiac and respiratory motion. DIR for coronary vessel wall MRI has been performed under breath-hold [86] or during free-breathing [85] in combination with diaphragmatic navigator; ECG-triggering has been used to address the presence of cardiac motion. As mentioned, DIR acquisitions are typically performed in 2D, however the use of local inversion pulses together with 3D imaging can enable larger anatomical coverage that allows for the visualization of the coronary wall along extensive portions of the vessel [90]. In one of the initial non-contrast enhanced coronary MRI vessel wall studies, the presence of positive remodeling in patients with subclinical coronary atherosclerosis was shown [91] (Figure 15.12). In a subsequent multiethnic study, increased coronary vascular remodeling was observed in subjects without prior history of CAD [92, 93]. Similarly, a different study showed increased positive remodeling of the coronary vessel wall in asymptomatic subjects [94]. Therefore, coronary vessel wall MRI holds promise as a screening tool in asymptomatic subjects for detection and quantification of positive remodeling and plaque burden. One of the main disadvantages of DIR, however, consists in the fact that it requires sophisticated acquisition planning, as data has to be collected during the period of optimal blood signal nulling and of minimal cardiac contraction. For these reasons, the reported failure rate of DIR acquisitions in clinical studies is particularly high (about 30%) [18, 86, 95].
Histopathologic and physiologic effect of bifurcation stenting: current status and future prospects
Published in Expert Review of Medical Devices, 2020
Anne Cornelissen, Liang Guo, Atsushi Sakamoto, Hiroyuki Jinnouchi, Yu Sato, Salome Kuntz, Rika Kawakami, Masayuki Mori, Raquel Fernandez, Daniela Fuller, Neel Gadhoke, Frank D. Kolodgie, Dipti Surve, Maria E. Romero, Renu Virmani, Aloke V. Finn
Conventional angiography provides only limited information about bifurcation anatomy, plaque distribution, and stent apposition and expansion. Intracoronary imaging techniques, such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have demonstrated advantages over conventional angiographic guidance and both techniques are highly recommended in complex lesions. With a superior penetration depth, IVUS allows for a more detailed characterization of plaque burden and moreover does not require vessel flushing or additional contrast during acquisition, whereas OCT, which has a ten times higher resolution than IVUS, provides superior images of the lumen surface and of lesional calcification, and allows for a more detailed guidance during the intervention, including the positioning of wires and stent struts [81]. Intracoronary imaging is indispensable to carefully evaluate bifurcation anatomy and plaque distribution, which is of particular importance in deciding whether a single stent is likely to maintain good flow in the side-branch or if a two-stent strategy should be the preferred approach from the outset [81]. Moreover, intracoronary imaging is highly recommended to rule out residual edge stenosis and dissection, and to evaluate stent expansion and apposition after the procedure [34]. In addition, for the particular case of 3D geometry reconstruction in bifurcation lesions, coronary CT angiography can importantly contribute to obtain fundamental morphometric data for patient-specific models of bifurcation lesions before and after PCI [82]. Integrative approaches that combine the high resolution of OCT with CT angiography [83] and/or functional measurements, such as fractional flow reserve (FFR) [84] have been used to enable more realistic CFD models, structural mechanical simulations, and fluid–structure interaction models of coronary bifurcations. However, randomized-controlled studies correlating lesion- and patient-specific pre- and post-procedural CFD simulations with lesion- and patient-specific outcomes are lacking. This data would be indispensable for the translation of biomechanical modeling to daily clinical practice, allowing for modeling and prediction of patient-specific local biomechanical factors that contribute to the intervention outcome, in order to set the stage for an improved patient-tailored bifurcation treatment.