Effect of synthetic bone replacement material of different size on shear stress resistance within impacted native and thermodisinfected cancellous bone: an in vitro femoral impaction bone grafting model.

Antibiotic carrier particles of variable size might influence mechanic properties within impacted thermodisinfected and native cancellous bone different. Herafill®G containing calciumsulfate and calciumcarbonate provides high local concentrations of gentamicin being important for revision surgery in infected joint replacements. Native and thermodisinfected cancellous bone derived from 6 to 7 months old piglets was used for in vitro impaction bone grafting and supplemented each with Herafill®G granules of two different sizes. Micromovement of implants related to shear force was measured in 29 specimens distributed in 6 groups. Thermodisinfected cancellous bone revealed a significant higher shear force resistance than native bone with a mean difference of 423.8 mdeg/Nm (p < 0.001) ranging within 95% confidence interval from 181.5 to 666.0 mdeg/Nm. Adding small granules to thermodisinfected bone did not reduce shear force resistance significantly since adding large granules to native bone improved it by 344.0 mdeg/Nm (p < 0.003). Shear force resistance was found higher at the distal region of the implant compared to a proximal point of measurement throughout all specimens. Less impaction impulses were necessary for thermodisinfected bone. Thermodisinfected cancellous bone might achieve a higher degree of impaction compared with native bone resulting in increased resistance against shear force since impaction was found increased distally. Supplementation of thermodisinfected bone with small granules of Herafill®G might be considered for application of local antibiotics. Large granules appeared more beneficial for supplementation of native bone. Heterogeneity of bone graft and technical aspects of the impaction procedure have to be considered regarding the reproducibility of femoral impaction bone grafting.

Establishment of a clinically relevant large animal model to assess the healing of metaphyseal bone.

Despite the high incidence of metaphyseal bone fractures in patients, the mechanisms underlying the healing processes are poorly understood due to the lack of suitable experimental animal models. Hence, the present study was conducted to establish and characterise a clinically relevant large-animal model for metaphyseal bone healing. Six female adult Merino sheep underwent full wedge-shaped osteotomy at the distal left femur metaphysis. The osteotomy was stabilised internally with a customised anatomical locking titanium plate that allowed immediate post-operative full-weight bearing. Bone healing was evaluated at 12 weeks post-fracture relative to the untouched right femur. Histological and quantitative micro-computed tomography results revealed an increased mineralised bone mass with a rich bone microarchitecture. New trabeculae healed by direct intramembranous ossification, without callus and cartilaginous tissue formation. Stiffness at the cortical and trabecular regions was comparable in both groups. Functional morphological analysis of the osteocyte lacunae revealed regularly arranged spherically shaped lacunae along with the canalicular network. Bone surface biochemical analysis using time-of-flight secondary-ion mass spectrometry showed high and homogeneously distributed levels of calcium and collagenous components. Ultrastructure imaging of the new trabeculae revealed a characteristic parallel arrangement of the collagen fibrils, evenly mineralised by the dense mineral substance. The specialised bone cells were also characterised by their unique structural features. Bone remodelling in the fractured femur was evident in the higher expression levels of prominent bone formation and resorption genes. In conclusion, the novel metaphyseal fracture model is beneficial for studying healing and treatment options for the enhancement of metaphyseal bone defects.

Visfatin alters the cytokine and matrix-degrading enzyme profile during osteogenic and adipogenic MSC differentiation.

OBJECTIVES: Age-related bone loss is associated with bone marrow adiposity. Adipokines (e.g., visfatin, resistin, leptin) are adipocyte-derived factors with immunomodulatory properties and might influence differentiation of bone marrow-derived mesenchymal stem cells (MSC) in osteoarthritis (OA) and osteoporosis (OP). Thus, the presence of adipokines and MMPs in bone marrow and their effects on MSC differentiation were analyzed. METHODS: MSC and ribonucleic acid (RNA) were isolated from femoral heads after hip replacement surgery of OA or osteoporotic femoral neck fracture (FF) patients. Bone structural parameters were evaluated by microcomputed tomography (µCT). MSC were differentiated towards adipocytes or osteoblasts with/without adipokines. Gene expression (adipokines, bone marker genes, MMPs, TIMPs) and cytokine production was evaluated by realtime-polymerase chain reaction (realtime-PCR) and enzyme-linked immunosorbent assay (ELISA). Matrix mineralization was quantified using Alizarin red S staining. RESULTS: µCT showed an osteoporotic phenotype of FF compared to OA bone (reduced trabecular thickness and increased ratio of bone surface vs volume of solid bone). Visfatin and leptin were increased in FF vs OA. Visfatin induced the secretion of IL-6, IL-8, and MCP-1 during osteogenic and adipogenic differentiation. In contrast to resistin and leptin, visfatin increased MMP2 and MMP13 during adipogenesis. In osteogenically differentiated cells, MMPs and TIMPs were reduced by visfatin. Visfatin significantly increased matrix mineralization during osteogenesis, whereas collagen type I expression was reduced. CONCLUSION: Visfatin-mediated increase of matrix mineralization and reduced collagen type I expression could contribute to bone fragility. Visfatin is involved in impaired bone remodeling at the adipose tissue/bone interface through induction of proinflammatory factors and dysregulated MMP/TIMP balance during MSC differentiation.

[Influence of thermodisinfection on impaction of cancellous bone : An in vitro model of femoral impaction bone grafting]. / Einfluss der Thermodesinfektion auf die Impaktion spongiöser Knochen : Ein In-vitro-Modell für das femorale Impaction-Bone-Grafting.

BACKGROUND: The reconstruction of bony defects during endoprosthesis revision surgery using "impaction bone grafting" leads to the possibility of a longstanding osseous integration to achieve good clinical results. Native allogeneic cancellous bone is often used for the procedure. This study examines the influence of thermodisinfection on the impaction behaviour of cancellous bone of different geometries and on the cement distribution. METHODS: The cancellous bone was obtained from the femoral heads of 7­month old pigs. One half of the head was thermodisinfected while the other remained native. Bone chips with sizes of 3-5, 5-8 and 8-10 mm were produced. The impaction was performed in a cylinder model with an internal diameter of 30 mm and with standardized impaction force using an impactor with a weight of 1450 g. The best particle combination was used for the subsequent computer tomography examination of the cement distribution and the contact surface to the bone in different parts of the shaft in seven investigations. For statistic measurements two-dimensional variance analysis including repetitions of measurement and Bonferroni correction, the LSD post-hoc-zest and the Mann Whitney U Test were used. The error probability was set at α = 5%. The SPSS® for Windows software was used for the statistical analysis. RESULTS: The distribution of the cancellous and compacted bone also along the shaft revealed no significant difference between thermodisinfected and native cancellous bone at different levels (p > 0.05). Impacted native cancellous bone showed less inclusion of air, which resulted in a better distribution of density compared with thermodisinfected bone overall (p < 0.001). In the distal shaft area the cement volume was significantly larger in conjunction with the native bone. The overall area of cement penetration appeared to be significantly larger for native cancellous bone (p < 0.001). CONCLUSIONS: The impaction of thermodisinfected and native cancellous bone showed greater deformation of the processed bone without any significant difference in the maximum density reached at different levels. Cement volume and cement penetration were pronounced proximally in native and processed cancellous bone. The cement distribution was significantly more distal for the native bone. Distally, the stabilization of the shaft appears to be increasingly dependent on the density of the impacted spongiosa, while proximally, the penetration of the cement into cancellous bone seems to correlate with porosity.

[Disseminated osteolytic lesions in a 28-year-old refugee]. / Disseminierte osteolytische Läsionen bei einem 28-jährigen Flüchtling.

A 28-year-old Syrian refugee presented with right-sided knee pain and progressive deterioration of the general condition over the past months. Laboratory diagnostics revealed severe hypercalcemia due to primary hyperparathyroidism, and computed tomography (CT) scanning demonstrated disseminated osteolytic lesions throughout the skeleton. Histologically, these lesions were characterized by multinuclear giant cells (defining these lesions as so-called brown tumors). Finally, surgical removal of a jugular mass allowed the histopathologic diagnosis of a sporadic parathyroid carcinoma. In the patient, this condition was associated with a mutation in the HPRT2 gene locus.

Short-term glucocorticoid treatment causes spinal osteoporosis in ovariectomized rats.

PURPOSE: In humans, glucocorticoid-induced osteoporosis is the most common cause of medication-induced osteoporosis. Recent clinical data suggest that glucocorticoid therapy increases the risk of vertebral fractures within a short treatment period. Therefore, this study aimed at investigating vertebral bone in a rat model of glucocorticoid-induced postmenopausal osteoporosis. METHODS: Fifty Sprague-Dawley rats were randomly assigned into three groups: 1) untreated controls, 2) Sham-operated group, and 3) ovariectomized rats treated with glucocorticoid (dexamethasone) for 3 months (3M) after recovery from bilateral ovariectomy. Osteoporotic bone status was determined by means of the gold standard dual energy X-ray absorptiometry (DEXA) scan. Vertebral bodies were examined using µCT, histological analysis, mRNA expression analysis, and biomechanical compression testing. Further systemic effects were studied biochemically using serum marker analysis. RESULTS: Dexamethasone treatment showed at 3M a significantly lower bone mineral density in ovariectomized rats compared to Sham-operated control (p < 0.0001) as analyzed in vivo by DEXA. Furthermore, Z scores reached levels of -5.7 in the spine indicating sever osteoporotic bone status. Biomechanical testing of compression stability indicated a lower functional competence (p < 0.0001) in the spine of treated rats. µCT analysis showed significant reduction of bone volume density (BV/TV%; p < 0.0001), significantly enhanced trabecular spacing (Tb.Sp; p < 0.0001) with less trabecular number (Tb.N; p < 0.001) and complete loss of trabecular structures in glucocorticoid-treated ovariectomized rats. Histological analysis by osteoblast and osteoclast activities reflected a higher bone catabolism reflected by osteoclast counts by TRAP (p < 0.019) and lower bone catabolism indicated by ALP-stained area (p < 0.035).Serum analysis showed a significant increase in osteocalcin (p < 0.0001), osteopontin (p < 0.01) and insulin (p < 0.001) at 3M. Expression analysis of molecular markers in the vertebral body revealed lower expression in tenascin C in the OVX-steroid animals at 3M. CONCLUSIONS: Short-term glucocorticoid treatment of ovariectomized rats indicates according to DEXA standards a severe osteoporotic bone status in vertebral bone. Nonetheless, dysfunctional bone anabolism and enhanced bone catabolism are observed. Alterations of bone extracellular matrix proteins that correlate to inferior mechanical stability and affected microstructure were noticed and suggest further investigation. Treatment with dexamethasone was also seen to affect insulin and osteopontin levels and thus osteoblast function and maturation. This described animal model presents a recapitulation of clinically obtained data from early phase glucocorticoid-induced osteoporosis observed in patients.

Mixed testicular atrophy related to atherosclerosis: first lessons from the ApoE(-/-)/ LDL receptor(-/-) double knockout mouse model.

Age-related testicular changes are associated with declining spermatogenesis and testosterone levels. A relationship to atherosclerosis has never been investigated systematically. The ApoE(-/-)/LDL receptor(-/-) double knockout mouse model, providing a remarkable homology to human atherosclerosis, is an ideal tool to investigate spermatogenetic alterations in this context. Testes (n = 10) from ApoE(-/-)/LDL receptor(-/-) double knockout mice at the age of 80 weeks were perfused in vivo with contrast agent, harvested and scanned with micro-CT at (4.9 µm³) voxel size. Testes (n = 8) of C57/BL mice at the same age served as controls. Testis volume (mm³) and total vascular volume fraction (mm³) were quantified using micro-CT. Serum testosterone levels were determined. Testicular histology and epididymal sections were analysed for tubular structure, spermatogenetic scores and sperm count. The expression of protamine 2 as a marker for elongated spermatids, inflammation markers (CD4, F4/80) and hypoxia inducible factor 1 alpha (HIF1 alpha) were investigated using immunohistochemistry. ApoE(-/-)/LDL receptor(-/-) double knockout mice exhibit diminished testis and vascular volume fraction with respect to that of controls (p < 0.001). These findings were associated with a reduction of testosterone levels (p < 0.001). Mixed atrophy was present in 41% of the seminiferous tubuli in ApoE(-/-)/LDL receptor(-/-) double knockout mice at the age of 80 weeks. Sperm counts from the epididymis demonstrated a significant decrease in ApoE(-/-)/LDL receptor(-/-) double knockout mice (p < 0.001). In addition, sperm specific protamine 2 expression was decreased in testicular tissue and epididymis of ApoE(-/-)/LDL receptor(-/-) double knockout mice compared with that of control mice. Peritubular inflammatory infiltration and the expression of the hypoxia related marker was observed. Mixed testicular atrophy in ApoE(-/-)/LDL receptor(-/-) double knockout mice is linked to reduced testis volume, vascular volume fraction and low testosterone serum levels, suggesting a direct relation between atherosclerosis and disturbed spermatogenesis.

Influence of antibiotic pellets on pore size and shear stress resistance of impacted native and thermodisinfected cancellous bone: An in vitro femoral impaction bone grafting model.

INTRODUCTION: Morphology and mechanic properties of impacted cancellous bone are affected by carrier substances which provide high local concentrations of antibiotics. METHODS: Bone chips were taken from the femoral head of 6-7 months old piglets. One half was thermodisinfected and the other remained native. Ten specimens each were mixed with Herafill® antibiotic pellets and a control group of each 10 specimens respectively was examined. The cancellous bone was impacted according to Exeter technique and the implants were cemented. The distribution of the particles and the pores were defined with three dimensional computertomographic scan and shear force resistance was measured until failure. RESULTS: Shear force resistance was not measured significantly less for thermodisinfected (2.7 Nm) compared with native bone (3.5 Nm) and addition of antibiotic pellets reduced shear force resistance in both groups since this was significant for the native group. The average pore volume of the native bone specimens appeared significant smaller compared to the thermodisinfected group (p = 0.011) and the pore volume showed a negative correlation with shear force resistance (p = 0.044). Pore volume around the pellets was found significantly increased and it appeared smaller for native bone. The number of pellets located next to the implant showed a negative correlation with shear force resistance (p = 0.034) and the negative correlation increased for pellets below the tip of the shaft model (p = 0.024). CONCLUSION: Adding antibiotic pellets to native and thermodisinfected impacted cancellous bone increased pore volume since the area around the pellets showed increased porosity which correlated with reduced shear force resistance. Computertomographic three dimensional measurement of porosity might predict shear force resistance of impacted cancellous bone and improve impaction of bone grafting intraoperatively.

Analysis of microscopic bone properties in an osteoporotic sheep model: a combined biomechanics, FE and ToF-SIMS study.

The present study deals with the characterization of bone quality in a sheep model of postmenopausal osteoporosis. Sheep were sham operated ( n = 7), ovariectomized ( n = 6), ovariectomized and treated with deficient diet ( n = 8) or ovariectomized, treated with deficient diet and glucocorticoid injections ( n = 7). The focus of the study is on the microscopic properties at tissue level. Microscopic mechanical properties of osteoporotic bone were evaluated by a combination of biomechanical testing and mathematical modelling. Sample stiffness and strength were determined by compression tests and finite-element analysis of stress states was conducted. From this, an averaged microscopic Young's modulus at tissue level was determined. Trabecular structure as well as mineral and collagen distribution in samples of sheep vertebrae were analysed by micro-computed tomography and time-of-flight secondary ion mass spectrometry. In the osteoporotic sheep model, a disturbed fibril structure in the triple treated group was observed, but bone loss only occurred in form of reduced trabecular number and thickness and cortical decline, while quality of the residual bone was preserved. The preserved bone tissue properties in the osteoporotic sheep model allowed for an estimation of bone strength which behaves similar to the human case.

Quantitative 3D micro-CT imaging of the human feto-placental vasculature in intrauterine growth restriction.

OBJECTIVE: Placental vascular development matches fetal growth and development. Quantification of the feto-placental vasculature in placentas from pregnancies is complicated by intrauterine growth restriction (IUGR) revealed confounding results. Therefore, the feto-placental vascular volume in IUGR placentas was assessed by 3D micro-computed tomography (micro-CT). METHODS AND RESULTS: Placental probes from IUGR (n=24) and healthy control placentas (n=40) were perfused in situ with Microfil or BaSO(4) and randomly chosen samples were scanned by micro-CT. Using 3D images, we quantitated the feto-placental vascular volume fraction (VVF). A subanalysis was performed at three different levels, reaching from the chorionic plate artery (level A), to intermediate arteries (level B) and capillary system (level C). Results were complemented by histology. The significance of differences in vascular volume measurements was tested with analysis of variance [ANOVA]. RESULTS: Microfil perfused placentas showed a total vascular volume fraction of 20.5+/-0.9% in healthy controls. In contrast, the VVF decreased to 7.9+/-0.9% (p<0.001) in IUGR placentas. Significant differences were found between Microfil and BaSO(4) perfused placentas in the vascular volume fraction using micro-CT and histology. Micro-CT demonstrated localized concentric luminal encroachments in the intermediate arteries in placentas complicated by IUGR. CONCLUSION: Micro-CT imaging is feasible for quantitative analysis of the feto-placental vascular tree in healthy controls and pregnancies complicated by IUGR.

Diagnostic value of ex-vivo three-dimensional micro-computed tomography imaging of primary nonhematopoietic human bone tumors: osteosarcoma versus chondrosarcoma.

BACKGROUND: Osteosarcoma and chondrosarcoma are the most common nonhematopoietic primary malignancies of bone. However, unusual radiographic appearances can lead to delay in diagnosis and confusion with benign diseases. PURPOSE: To evaluate the feasibility of micro-computed tomography (CT) for the analysis of primary, nonhematopoietic human bone tumors ex vivo. MATERIAL AND METHODS: Samples from 12 human bone specimens (osteosarcoma, n=6; chondrosarcoma, n=6) obtained for diagnostic purposes were scanned using industrial X-ray film without amplifier foil and scanned with micro-CT (7- and 12-microm-cubic voxels). Trabecular bone CT "density" and tumor matrix CT "density" were determined, and results were compared with those obtained from a detailed conventional histopathologic analysis of corresponding cross-sections. The significance of differences in grayscale measurements was tested with analysis of variance. RESULTS: Micro-CT provided quantitative information on bone morphology equivalent to histopathological analysis. We established grayscale measurements by which tumor matrices of chondrosarcoma and osteosarcoma could be radiographically categorized following histological classifications (P<0.001). CONCLUSION: Micro-CT is feasible for the analysis and differentiation of human osteosarcoma and chondrosarcoma.

Calcium phosphate bone cement/mesoporous bioactive glass composites for controlled growth factor delivery.

Calcium phosphate (CaP) bone cements are widely used for the treatment of bone defects and have been proposed to serve as a delivery platform for therapeutic drugs, proteins and growth factors into the defect region. However, they lack sufficient porosity to allow immediate bone ingrowth and thus foster rapid integration into the bone tissue. In this study we investigated a composite prepared from a hydroxyapatite forming bone cement and mesoporous bioactive glass (MBG) granules as a potential carrier for biologically active proteins. The mechanical properties of the composite were not compromised by up to 10 wt% MBG granule addition, which can be attributed to the strong interface between the cement matrix and MBG particles, however this modification induced a significant increase in porosity within 3 weeks ageing in an aqueous liquid. The release profiles of two proteins, lysozyme and the vascular endothelial growth factor (VEGF), could be controlled when they were loaded onto MBG granules that were subsequently embedded into the cement when compared to direct loading into the cement precursor. Both proteins were also demonstrated to maintain their biologic activity during embedding and release from the composite. These findings suggest the CaP bone cement/MBG composite developed in this study as a potential delivery platform for growth factors or other bioactive substances.

The Relationship between Brachycephalic Head Features in Modern Persian Cats and Dysmorphologies of the Skull and Internal Hydrocephalus.

BACKGROUND: Cat breeders observed a frequent occurrence of internal hydrocephalus in Persian cats with extreme brachycephalic head morphology. OBJECTIVE: To investigate a possible relationship among the grade of brachycephaly, ventricular dilatation, and skull dysmorphologies in Persian cats. ANIMALS: 92 Persian-, 10 Domestic shorthair cats. METHODS: The grade of brachycephaly was determined on skull models based on CT datasets. Cranial measurements were examined with regard to a possible correlation with relative ventricular volume, and cranial capacity. Persians with high (peke-face Persians) and lower grades of brachycephaly (doll-face Persians) were investigated for the presence of skull dysmorphologies. RESULTS: The mean cranial index of the peke-face Persians (0.97 ± 0.14) was significantly higher than the mean cranial index of doll-face Persians (0.66 ± 0.04; P < 0.001). Peke-face Persians had a lower relative nasal bone length (0.15 ± 0.04) compared to doll-face (0.29 ± 0.08; P < 0.001). The endocranial volume was significantly lower in doll-face than peke-face Persians (89.6 ± 1.27% versus 91.76 ± 2.07%; P < 0.001). The cranial index was significantly correlated with this variable (Spearman's r: 0.7; P < 0.0001). Mean ventricle: Brain ratio of the peke-face group (0.159 ± 0.14) was significantly higher compared to doll-face Persians (0.015 ± 0.01; P < 0.001). CONCLUSION AND CLINICAL RELEVANCE: High grades of brachycephaly are also associated with malformations of the calvarial and facial bones as well as dental malformations. As these dysmorphologies can affect animal welfare, the selection for extreme forms of brachycephaly in Persian cats should be reconsidered.

Changes in Dynamic Pelvic Floor Magnet Resonance Imaging and Patient Satisfaction after Resection Rectopexy for Obstructed Defecation Syndrome.

PURPOSE: Resection rectopexy (RR) provides good functional results and low recurrence rates for the treatment of obstructed defecation syndrome based on rectal prolapse and cul-de-sac syndrome, whereas little is known about changes in pelvic floor dynamics and patient satisfaction after surgery. MATERIALS AND METHODS: Within three years 26 consecutive female patients were prospectively included. Indications for RR (22 laparoscopic, 3 primary open and 1 converted-to-open) were rectal prolapse III° in 11 patients and cul-de-sac syndrome in 15 patients. Patients' quality of life (QOL), fecal behavior and defecation-associated pain were investigated before and after surgical treatment using anamnesis and clinical examination, Rand 36-idem health survey (SF-36), Cleveland-Clinic Incontinence Score (CCIS) and the visual analog scale for defecation-associated pain (VAS). Dynamic pelvic floor magnet resonance imaging (dPF-MRI) was used for the investigation of changes in pelvic floor anatomy and function before and after surgery. RESULTS: RR improved the rate of fecal incontinence (p < 0.01) and CCIS (p = 0.01). The use of laxatives (p = 0.01), the need for self-digitation (p = 0.02) and VAS (p < 0.01) were decreased, leading to improvements in QOL (overall p < 0.01). RR led to shortening of the H-line but not of the M-line under rest (p < 0.01) and during defecation (p = 0.04). A rectocele was co-incident in all patients in dPF-MRI before surgery. RR led to a reduction (p < 0.01) and declined protrusion (p = 0.03) of the rectocele. This results in a decreased rate of cul-de-sac (p < 0.01) and increased rate of complete defecation (p < 0.01) after surgery. At the 36-month follow-up no recurrence was observed. CONCLUSION: RR promises high rates of patient satisfaction and improvement in pelvic floor anatomy in select patients. KEY POINTS: • RR improves the pelvic floor anatomy of patients suffering from ODS. • RR improves the QOL of patients suffering from ODS. • An improvement in pelvic floor anatomy led to an improved QOL. • RR is an adequate treatment for select patients suffering from ODS.

Nano-Computed Tomography: Technique and Applications.

UNLABELLED: Nano-computed tomography (nano-CT) is an emerging, high-resolution cross-sectional imaging technique and represents a technical advancement of the established micro-CT technology. Based on the application of a transmission target X-ray tube, the focal spot size can be decreased down to diameters less than 400 nanometers (nm). Together with specific detectors and examination protocols, a superior spatial resolution up to 400 nm (10 % MTF) can be achieved, thereby exceeding the resolution capacity of typical micro-CT systems. The technical concept of nano-CT imaging as well as the basics of specimen preparation are demonstrated exemplarily. Characteristics of atherosclerotic plaques (intraplaque hemorrhage and calcifications) in a murine model of atherosclerosis (ApoE (-/-)/LDLR(-/-) double knockout mouse) are demonstrated in the context of superior spatial resolution in comparison to micro-CT. Furthermore, this article presents the application of nano-CT for imaging cerebral microcirculation (murine), lung structures (porcine), and trabecular microstructure (ovine) in contrast to micro-CT imaging. This review shows the potential of nano-CT as a radiological method in biomedical basic research and discusses the application of experimental, high resolution CT techniques in consideration of other high resolution cross-sectional imaging techniques. KEY POINTS: Nano-computed tomography is a high resolution CT-technology for 3D imaging at sub-micrometer resolution. The technical concept bases on a further development of the established ex-vivo-micro-CT technology. By improvement of the spatial resolution, structures at a cellular level become visible (e.g. osteocyte lacunae).

Quantitative 3D micro-CT imaging of human lung tissue.

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.

Quantitative CT imaging of the spatio-temporal distribution patterns of vasa vasorum in aortas of apoE-/-/LDL-/- double knockout mice.

OBJECTIVE: To investigate the distribution of vasa vasorum (VV) relative to advanced atherosclerotic lesions (calcified, fibrotic or hemorrhaged) along the aortic wall of apoE-/-/LDL-/- mice at the age of 25 and 80 weeks using high-resolution nano-CT. METHODS: Aortas from male apoE-/-/LDL-/- mice at the age of 25 weeks (n=4) and 80 weeks (n=7) were infused in situ with contrast agent and harvested for scanning with nano-CT. The spatial distribution of vasa vasorum [number and area/cross-section (mm2)] was compared to aortic luminal cross-sectional area and plaque cross-sectional area in the ascending aorta, aortic arch and descending aorta. Results were complemented with co-localized histology. RESULTS: The number and total luminal cross-sectional area of VV showed a significant decrease in the ascending aorta and aortic arch from 25 to 80 weeks but not in the descending aorta. The number and cross-sectional area of VV showed significant local differences depending on whether it was near a fibrotic, and hemorrhaged or calcified plaque in animals at the age of 80 weeks. Area of VV progressively increased along the aorta from least in the ascending aorta