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.

[Micro-CT analysis of cancellous bone fragments from the distal radius fracture zone in osteoporosis]. / Mikro-CT Analyse spongiöser Fragmente aus der distalen Radiusfrakturzone bei Osteoporose.

The incidence and prevalence of osteoporosis must be considered to continue to increase significantly due to the expected demographic development and environmental changes. In the diagnosis and staging of osteoporosis the three-dimensional bone structure should be as important as the bone mass or the mineral content of the bone. In this study, microfragments were taken from distal radius fracture zones and investigated in Micro-CT scans. Patients in which osteodensitometry of the lumbal spine had revealed osteoporosis in were found to have significantly reduced bone mass, bone density and trabecular thickness. Trabecular fractures which were found in non-osteoporotic patients even in robust trabeculae were detected by the two-dimensional analysis in thin locations and arborizations. Despite some trabeculae turned out to be very small the differences in the histomorphometry and the quality of trabecular fractures in osteoporotic as well as non-osteoporotic patients could be visualized very good in the Micro-CT analysis.

[Ultrasonography as a diagnostic measure in the rupture of fibular ligaments. Comparative study: sonography versus radiological investigations]. / Die sonographische Untersuchung in der Diagnostik der fibularen Bandruptur. Eine vergleichende Studie: Sonographie versus Röntgenuntersuchung.

PURPOSE: The present prospective clinical study was designed to verify the value of ultrasound examination concerning injuries of the fibular ligaments of the ankle using functional examinations under ultrasound supervision. METHOD: 34 patients who had sustained a lesion of the fibular ligaments of the ankle were compared with 42 healthy persons. The lateral malleolus and the collum tali were used as reproducible bony landmarks in ultrasound. The distance between those two points is first of all was measured in neutral position and later on under the influence of supinating force of 15 kp using a Telos fixation device. RESULTS: The average lateral opening of the upper ankle joint measured with the dynamic ultrasound examination was 4.4 mm (1-12 mm) in the group of patients who had been suffering from rupture of the fibular ligaments. In comparison the average lateral opening of the healthy contralateral ankle was 3.9 mm (1-9 mm). The control group showed an average lateral opening of 0.9 mm (0-5 mm). CONCLUSION: Direct ultrasonic visualisation of the fibular ligament is not yet reliable. The described method allows an estimation of the stability of the fibular ligaments even in cases of chronic instability. The ultrasound investigation method discussed is difficult to handle and for that reason it cannot replace the standardised x-ray examination.

[Standardized ultrasound examination of the ankle joint. Clarification of ultrasound standard image sections by corresponding MRI sections]. / Standardisierte sonographische Untersuchung des Sprunggelenkes. Erläuterungen der sonographischen Standard-Schnittebenen durch korrespondierende MRT-Schnitte.

AIM: The sonographical examination of the ankle was demonstrated in five standard cross-sections presented by the DEGUM (German Society for the Development of Ultrasonography in the Locomotor Apparatus) and compared with corresponding MRI cross-sections. METHOD: The sonographical examination was done in a real-time method with an ultrasound unit Type Versa (Siemens, Erlangen, Germany) and with a linear transducer (frequency 7.5 Mhz). The MRI tomographies were taken in two planes with the unit Type Magnetom (Siemens, Erlangen, Germany) with a 1.5 Tesla head-coil in T1- and T2-weighted spin echo sequences. RESULTS: Focus on the ventral, lateral and dorsal region provided a good overview of the superior ankle joint and the periarticular soft tissues. CONCLUSION: Being a cross-sectional method, the sonographical examination of the ankle joint offers additional information with regard to pathological changes of the joint and the periarticular soft-tissues.