3D Imaging of vascular networks for biophysical modeling of perfusion distribution within the heart

American Journal of Physiology-Heart and Circulatory Physiology

Wijngaard

et al. 2016

van Horssen P, van Lier MG, van den Wijngaard JP, VanBavel E, Hoefer IE, Spaan JA, Siebes M. Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume. Am J Physiol Heart Circ Physiol 310: H839 -H846, 2016. First published January 29, 2016 doi:10.1152/ajpheart.00728.2015.-Computational predictions of the functional stenosis severity from coronary imaging data use an allometric scaling law to derive hyperemic blood flow (Q) from coronary arterial volume (V), Q ϭ ␣V ␤ . Reliable estimates of ␣ and ␤ are essential for meaningful flow estimations. We hypothesize that the relation between Q and V depends on imaging resolution. In five canine hearts, fluorescent microspheres were injected into the left anterior descending coronary artery during maximal hyperemia. The coronary arteries of the excised heart were filled with fluorescent cast material, frozen, and processed with an imaging cryomicrotome to yield a three-dimensional representation of the coronary arterial network. The effect of limited image resolution was simulated by assessing scaling law parameters from the virtual arterial network at 11 truncation levels ranging from 50 to 1,000 m segment radius. Mapped microsphere locations were used to derive the corresponding relative Q using a reference truncation level of 200 m. The scaling law factor ␣ did not change with truncation level, despite considerable intersubject variability. In contrast, the scaling law exponent ␤ decreased from 0.79 to 0.55 with increasing truncation radius and was significantly lower for truncation radii above 500 m vs. 50 m (P Ͻ 0.05). Hyperemic Q was underestimated for vessel truncation above the reference level. In conclusion, flow-crown volume relations confirmed overall power law behavior; however, this relation depends on the terminal vessel radius that can be visualized. The scaling law exponent ␤ should therefore be adapted to the resolution of the imaging modality. FRACTIONAL FLOW RESERVE (FFR) has been shown to be a reliable and a widely accepted method to assess whether a coronary artery stenosis is responsible for myocardial ischemia (11). Conceptually, FFR is defined as the hyperemic flow in a vessel with a stenosis relative to the hypothetical hyperemic flow in the undiseased vessel. In practice, FFR is measured invasively as the ratio between pressure distal to a stenosis and aortic pressure, during adenosine-induced hyperemia. This requires passing of a guide wire with a pressure sensor through the stenosis. Despite the reliability of this method, risks of vessel and plaque rupture, procedure time, and costs have inspired the search for new less-invasive alternatives for assessing FFR (18), based on computational methods applied to arterial models obtained from angiography (27) or CT (6). By using experimentally established form-function relationships, coronary flow can be calculated from image-derived morphological data. These relationships are expressed in terms of allometric scaling laws r...

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Section: Methodsmentioning

confidence: 99%

Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume

American Journal of Physiology-Heart and Circulatory Physiology

Wijngaard

et al. 2016

show abstract

“…The objective of this study was to demonstrate the feasibility of the imaging cryomicrotome [10][11][12][13] to visualize monocytes at μm resolution on a 3D level, in conjunction with the coronary microvascular network. This imaging modality has been successfully employed in the assessment of vascular adaptation due to cryoablation [14], and in the detection of coronary collateral vessels [10][11][12][13], but not in conjunction with monocyte detection.…”

Section: Introductionmentioning

confidence: 99%

“…This imaging modality has been successfully employed in the assessment of vascular adaptation due to cryoablation [14], and in the detection of coronary collateral vessels [10][11][12][13], but not in conjunction with monocyte detection. We utilized different animal models and examined various fluorescent probes for cellular imaging, with a focus on monocytes.…”

Section: Introductionmentioning

confidence: 99%

Detection and quantification methods of monocyte homing in coronary vasculature with an imaging cryomicrotome

Hakimzadeh

Journal of Molecular and Cellular Cardiology

et al. 2014

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“…Frozen hearts were immersed in a cylindrical container containing 5% carboxymethylcellulose sodium solvent supplemented with Indian ink and frozen at Ϫ20°C. All samples were processed with a custom-built automated imaging cryomicrotome (26,27). Hearts were alternately cut at 14-m slice thickness and the block face was imaged using a 16-bit cooled CCD camera (Apogee Alta U-16) with an adjustable focus lens (Nikon 70 -180 mm).…”

Section: Methodsmentioning

confidence: 99%

Selective subepicardial localization of monocyte subsets in response to progressive coronary artery constriction

Hakimzadeh

American Journal of Physiology-Heart and Circulatory Physiology

et al. 2016

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