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Optical projection tomography permits efficient assessment of infarct volume in the murine heart postmyocardial infarction.

Zhao X, Wu J, Gray CD, McGregor K, Rossi AG, Morrison H, Jansen MA, Gray GA - Am. J. Physiol. Heart Circ. Physiol. (2015)

Bottom Line: Experimental studies therefore commonly assess injury by histological analysis of sections sampled from the infarcted heart, an approach that is labor intensive, can be subjective, and does not fully assess the extent of injury.Tissue processing for OPT did not compromise subsequent immunohistochemical detection of endothelial cell and inflammatory cell markers.OPT is thus a nondestructive, efficient, and accurate approach for routine in vitro assessment of murine myocardial infarct volume.

View Article: PubMed Central - PubMed

Affiliation: BHF/University Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom;

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3D (A, B) and 2D (C, D) quantification of infarct size acquired by MRI, OPT, and histology. This figure shows a section through the same heart viewed by MRI (A), OPT (B and D), and histology (C). For 3D infarct volume measurement, in images generated by T2* weighted LGE-MRI (A), semiautomatic thresholding permitted separation of viable myocardium (black) from infarcted myocardium [white after injection of gadolinium (Gd) contrast, with yellow contour]. In OPT reconstructions, infarct threshold setting was based on weaker emission from the infarct scar, highlighted in red (B). For 2D infarct area measurement, the infarct area is identified by blue staining in Masson's trichrome-stained sections (C). D: the same section viewed using OPT, in both the infarct is traced in red. In all images, signal associated with the pericardium and the fluid within the pericardial sac (in in vivo MR only) is manually excluded for analysis.
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Figure 2: 3D (A, B) and 2D (C, D) quantification of infarct size acquired by MRI, OPT, and histology. This figure shows a section through the same heart viewed by MRI (A), OPT (B and D), and histology (C). For 3D infarct volume measurement, in images generated by T2* weighted LGE-MRI (A), semiautomatic thresholding permitted separation of viable myocardium (black) from infarcted myocardium [white after injection of gadolinium (Gd) contrast, with yellow contour]. In OPT reconstructions, infarct threshold setting was based on weaker emission from the infarct scar, highlighted in red (B). For 2D infarct area measurement, the infarct area is identified by blue staining in Masson's trichrome-stained sections (C). D: the same section viewed using OPT, in both the infarct is traced in red. In all images, signal associated with the pericardium and the fluid within the pericardial sac (in in vivo MR only) is manually excluded for analysis.

Mentions: For 3D quantification and comparison of infarct size, LGE-MRI image files were first converted to Digital Imaging and Communications in Medicine (DICOM) format, the international standard for medical images and related information. For LGE-MRI, infarct was identified by semiautomatic threshold setting with CAAS software (Pie Medical) to allow quantification of viable and infarcted myocardium (Fig. 2A). For OPT imaging, 3D volume quantification was performed using Analyze 11 (AnalyzeDirect, Overland Park, KS). In brief, reconstructed tomographic image files were imported into Analyze, then intensity thresholds were adjusted manually for one slice to achieve the optimum delineation between viable and infarcted tissue. A standard region growing algorithm within Analyze then allowed identification of regions of interest (ROIs) for infarct volume within that slice. Areas away from the infarcted ventricle that had similar pixel intensity e.g., the pericardium, were manually excluded (see Fig. 2B). This process was repeated at intervals of 10–20 slices throughout the infarct (260–340 slices), and then ROIs were propagated automatically for all slices in between the manually adjusted slices, forming an infarct ROI for the whole left ventricle (LV). Similarly, LV volume was determined by manually segmenting epicardial and endocardial contours at intervals of every 50 slices (360–450 slices), with automatic propagation of contours for all slices in between. LV volume was then calculated as the difference between epicardial and endocardial volumes. The pixel intensity threshold of the infarcted area was adjusted in both software packages so that only the lesion was selected. Infarct size was calculated as a proportion of LV volume (infarct volume/total LV volume × 100, LV volume includes viable myocardium above ligation). All OPT analyses were performed in a blinded manner and independently of MR images.


Optical projection tomography permits efficient assessment of infarct volume in the murine heart postmyocardial infarction.

Zhao X, Wu J, Gray CD, McGregor K, Rossi AG, Morrison H, Jansen MA, Gray GA - Am. J. Physiol. Heart Circ. Physiol. (2015)

3D (A, B) and 2D (C, D) quantification of infarct size acquired by MRI, OPT, and histology. This figure shows a section through the same heart viewed by MRI (A), OPT (B and D), and histology (C). For 3D infarct volume measurement, in images generated by T2* weighted LGE-MRI (A), semiautomatic thresholding permitted separation of viable myocardium (black) from infarcted myocardium [white after injection of gadolinium (Gd) contrast, with yellow contour]. In OPT reconstructions, infarct threshold setting was based on weaker emission from the infarct scar, highlighted in red (B). For 2D infarct area measurement, the infarct area is identified by blue staining in Masson's trichrome-stained sections (C). D: the same section viewed using OPT, in both the infarct is traced in red. In all images, signal associated with the pericardium and the fluid within the pericardial sac (in in vivo MR only) is manually excluded for analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4537945&req=5

Figure 2: 3D (A, B) and 2D (C, D) quantification of infarct size acquired by MRI, OPT, and histology. This figure shows a section through the same heart viewed by MRI (A), OPT (B and D), and histology (C). For 3D infarct volume measurement, in images generated by T2* weighted LGE-MRI (A), semiautomatic thresholding permitted separation of viable myocardium (black) from infarcted myocardium [white after injection of gadolinium (Gd) contrast, with yellow contour]. In OPT reconstructions, infarct threshold setting was based on weaker emission from the infarct scar, highlighted in red (B). For 2D infarct area measurement, the infarct area is identified by blue staining in Masson's trichrome-stained sections (C). D: the same section viewed using OPT, in both the infarct is traced in red. In all images, signal associated with the pericardium and the fluid within the pericardial sac (in in vivo MR only) is manually excluded for analysis.
Mentions: For 3D quantification and comparison of infarct size, LGE-MRI image files were first converted to Digital Imaging and Communications in Medicine (DICOM) format, the international standard for medical images and related information. For LGE-MRI, infarct was identified by semiautomatic threshold setting with CAAS software (Pie Medical) to allow quantification of viable and infarcted myocardium (Fig. 2A). For OPT imaging, 3D volume quantification was performed using Analyze 11 (AnalyzeDirect, Overland Park, KS). In brief, reconstructed tomographic image files were imported into Analyze, then intensity thresholds were adjusted manually for one slice to achieve the optimum delineation between viable and infarcted tissue. A standard region growing algorithm within Analyze then allowed identification of regions of interest (ROIs) for infarct volume within that slice. Areas away from the infarcted ventricle that had similar pixel intensity e.g., the pericardium, were manually excluded (see Fig. 2B). This process was repeated at intervals of 10–20 slices throughout the infarct (260–340 slices), and then ROIs were propagated automatically for all slices in between the manually adjusted slices, forming an infarct ROI for the whole left ventricle (LV). Similarly, LV volume was determined by manually segmenting epicardial and endocardial contours at intervals of every 50 slices (360–450 slices), with automatic propagation of contours for all slices in between. LV volume was then calculated as the difference between epicardial and endocardial volumes. The pixel intensity threshold of the infarcted area was adjusted in both software packages so that only the lesion was selected. Infarct size was calculated as a proportion of LV volume (infarct volume/total LV volume × 100, LV volume includes viable myocardium above ligation). All OPT analyses were performed in a blinded manner and independently of MR images.

Bottom Line: Experimental studies therefore commonly assess injury by histological analysis of sections sampled from the infarcted heart, an approach that is labor intensive, can be subjective, and does not fully assess the extent of injury.Tissue processing for OPT did not compromise subsequent immunohistochemical detection of endothelial cell and inflammatory cell markers.OPT is thus a nondestructive, efficient, and accurate approach for routine in vitro assessment of murine myocardial infarct volume.

View Article: PubMed Central - PubMed

Affiliation: BHF/University Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom;

Show MeSH
Related in: MedlinePlus