We evaluated microfocal X-ray-computed tomography (micro-CT) as a method to visualize lung architecture two and three dimensionally and to obtain morphometric data. Inflated porcine lungs were fixed by formaldehyde ventilation. Tissue samples (8-mm diameter, 10-mm height) were stained with osmium tetroxide, and 400 projection images (1,024 x 1,024 pixel) were obtained. Continuous isometric micro-CT scans (voxel size 9 microm) were acquired to reconstruct two- and three-dimensional images. Tissue samples were sectioned (8-microm thickness) for histological analysis. Alveolar surface density and mean linear intercept were assessed by stereology-based morphometry in micro-CT scans and corresponding histological sections. Furthermore, stereology-based morphometry was compared with morphometric semi-automated micro-CT analysis within the same micro-CT scan. Agreement of methods was assessed by regression and Bland-Altman analysis. Comparing histology with micro-CT, alveolar surface densities (35.4 +/- 2.4 vs. 33.4 +/- 1.9/mm, P < 0.05) showed a correlation (r = 0.72; P = 0.018) with an agreement of 2 +/- 1.6/mm; the mean linear intercept (135.7 +/- 14.5 vs. 135.8 +/- 15 microm) correlated well (r = 0.97; P < 0.0001) with an agreement of -0.1 +/- 3.4 microm. Semi-automated micro-CT analysis resulted in smaller alveolar surface densities (33.4 +/- 1.9 vs. 30.5 +/- 1/mm; P < 0.01) with a correlation (r = 0.70; P = 0.023) and agreement of 2.9 +/- 1.4/mm. Non-destructive micro-CT scanning offers the advantage to visualize the spatial tissue architecture of small lung samples two and three dimensionally.
Structural data about the human lung fine structure are mainly based on stereological methods applied to serial sections. As these methods utilize 2D images, which are often not contiguous, they suffer from inaccuracies which are overcome by analysis of 3D micro-CT images of the never-sectioned specimen. The purpose of our study was to generate a complete data set of the intact 3-dimensional architecture of the human acinus using high-resolution synchrotron-based micro-CT (synMCT). A human lung was inflation-fixed by formaldehyde ventilation and then scanned in a 64-slice CT over its apex to base extent. Lung samples (8-mm diameter, 10-mm height, n = 12) were punched out, stained with osmium tetroxide, and scanned using synMCT at (4μm)3 voxel size. The lung functional unit (acinus, n = 8) was segmented from the 3D tomographic image using an automated tree-analysis software program. Morphometric data of the lung were analyzed by ANOVA. Intraacinar airways branching occurred over 11 generations. The mean acinar volume was 131.3 ± 29.2 mm3 (range 92.5 – 171.3 mm3) and the mean acinar surface was calculated with 1012 ± 26 cm2. The airway internal diameter (starting from the bronchiolus terminalis) decreases distally from 0.66 ± 0.04 mm to 0.34 ± 0.06 mm (p < 0.001) and remains constant after the 7th generation (p < 0.5). The length of each generation ranges between 0.52 – 0.93 mm and did not show significant differences between the second and 11th generation. The branching angle between daughter branches varies between 113–134° without significant differences between the generations (p < 0.3). This study demonstrates the feasibility of quantitating the 3D structure of the human acinus at the spatial resolution readily achievable using synMCT.
Purpose: To assess the feasibility of micro-CT for obtaining quantitative volumetric and morphologic information of changes in soft tissue, respiratory tracts and vascularization in fibrotic, emphysematous and non-diseased human lung specimens. Materials and Methods: Specimens from autopsy or lung explantation with lung fibrosis of UIP pattern (n?=?22) or centrilobular emphysema (n?=?10) were scanned by micro-CT and compared to controls (n?=?22). Imaging was performed subsequent to intravascular contrast enhancement for the assessment of the vascular volume fraction. The soft tissue and air fraction were quantified after the fixation of ventilated lungs followed by tissue contrast enhancement using osmium. Aiming an artifact-free 3?D reconstruction of lung acini, synchrotron-based micro-CT scans of specimens with emphysema (n?=?5) and non-diseased tissue (n?=?6) was performed. Micro-CT imaging was complemented by histology for the demonstration of comparable findings. Results: Quantitative analysis showed a significant increase of the soft tissue fraction, equivalent to a decrease of the air fraction in fibrotic lungs compared to controls (p?0.001) and a significant reduction of the vascular volume fraction compared to controls (p?0.02). Specimens with emphysema demonstrated a significant increase of the air fraction with a decrease in soft tissue compared to controls (p?0.001). 3?D reconstructions of lung acini worked successfully in non-diseased tissue but failed in fibrotic and emphysematous lungs. Conclusion: Our findings indicate micro-CT?s technical feasibility to assess quantitative and morphological data from diseased and non-diseased human lung specimens. Citation Format:
A 49-year-old patient sustained an ipsilateral fracture of the lateral femoral neck and distal femoral shaft, which were treated with a long intramedullary nail with a hip screw component. Both fractures did not heal, and both nonunion sites were revised by reosteosynthesis with a dynamic hip screw for the femoral neck and a locked intramedullary nail for the shaft region combined with autogenous bone grafting at both sites. At 14 months from injury and after 2 operations, both nonunions persisted. At a third surgery, 1 kit of recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge was applied to each site, without any modification of the osteosynthesis or additional bone grafting. The lateral femoral neck and the femoral shaft consolidated 24 and 30 weeks, respectively, after the rhBMP-2 application, and the patient resumed his work as industrial worker after 7 months after his last surgery. We believe this is the first study to report the successful use of 2 kits of rhBMP-2 in a double nonunion of the femur.
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