Iterative micro-tomography of biopsy samples from truncated projections with quantitative gray values.

Three-dimensional reconstruction from truncated two-dimensional projections cannot be solved analytically without prior knowledge of the sample or access to the non-truncated projections. To suppress reconstruction artifacts in region of interest (ROI) or local tomography, an iterative algorithm has been devised based on back-projection and re-projection, assuming an approximately cylindrical shape of the entire sample of general homogeneity, which is especially applicable for micro-tomography of biopsy samples from biological tissue. Tomographic reconstruction is iteratively refined by minimizing the mismatch between an empty ROI and the reconstruction from the difference between measured sinogram and forward projected ROI reconstruction. By numerical simulation and experimental demonstration, it is shown that the algorithm is not only able to reconstruct quantitative gray values, but also to reduce artifacts of peripheral glow, and may lead to increased image sharpness. The method is particularly suitable for examination of biopsy/autopsy-samples of soft tissue by micro/nano-computed tomography.

Three-dimensional resolution enhancement in fluorescence microscopy by harmonic excitation.

A method for increasing lateral as well as axial resolution in fluorescence microscopy is presented. A passband with a high cutoff frequency throughout reciprocal space can be achieved by illumination of the object with spatially harmonic excitation patterns generated by the interference of two collimated laser beams. Theoretical calculations show an almost isotropic point-spread function with a FWHM near 100 nm.

True optical resolution beyond the Rayleigh limit achieved by standing wave illumination.

During the last decade, various efforts have been undertaken to enhance the resolution of optical microscopes, mostly because of their importance in biological sciences. Herein, we describe a method to increase the resolution of fluorescence microscopy by illuminating the specimen with a mesh-like interference pattern of a laser source and electronic postprocessing of the images. We achieve 100-nm optical resolution, an improvement by a factor of more than 2 compared with standard fluorescence microscopy and of 1.5 compared with confocal scanning.

Atomic force microscopy in effusion cytology.

OBJECTIVE: To investigate whether atomic force microscopy (AFM) in combination with classical light microscopy allows simple identification of surface structures of cells from pleural and ascitic fluids for diagnostic purposes in place of scanning electron microscopy (SEM). STUDY DESIGN: We examined a total of 180 cells obtained from 9 reactive pleural or peritoneal effusions, 14 associated with carcinomatosis from histologically confirmed tumors and 5 from mesotheliomas. Cells of interest were selected in air-dried, uncovered, May-Grünwald-Giemsa (MGG)-stained smears and subsequently investigated by AFM. Incorporation of a very compact AFM scanner into the nose piece of a conventional Axioscope light microscope allowed alternating application of both techniques. RESULTS: AFM was able to detect cell surface structures, such as microvilli, phagocytic pits, secretory blebs and lytic holes. The image resolution was sufficient but not as good as that with SEM. We found differences in number, length and diameter of microvilli between cells from mesotheliomas and from metastatic adenocarcinomas. CONCLUSION: As AFM can be carried out in combination with light microscopy quickly and easily on uncovered, MGG-stained smears, we propose this method as a suitable tool for obtaining additional useful information in routine cytologic diagnosis of effusions.

[Computer supported documentation of diagnostic results and interpretation of bone scintigraphy]. / Computergestützte Befunddokumentation und -interpretation der Skelettszintigraphie.

A PC software program with a graphical users platform was developed which enables the transfer of bone scintigraphy results to vectorgraphy-based skeleton images, and to implement a fully automatic anatomical localization definition of lesions. Documentation of the results is made possible by a complete, conventional structured medical letter. Additional information such as data on the patient, diagnostic methods and results, sacro-iliacal indexes, recommendations and remarks can be added to the scintigrams. By implementation of a database and PCX-interface, the system is open.

Effect of aortic sclerosis on bone mineral measurements by dual-photon absorptiometry.

Measurements of the bone mineral content (BMC) of lumbar spine by dual-photon absorptiometry (DPA) are performed mainly in the anteroposterior (AP) projection. Due to superimposition of the abdominal aorta, the BMC measured for patients with aortic calcification usually is too high. To determine the influence of aortic calcifications, DPA scans were performed in the AP-projection on 100 dissected abdominal aortae with different degrees of atherosclerosis placed on a human lumbar spine cast in lucite. The measured values were compared with those obtained in the same projection without the aortae. The average increase of the BMC values relative to the mean for the vertebrae L2 to L4 for aortae with severe complicated lesions, i.e., those containing larger amounts of calcium, was 0.03 g/cm2, with a maximum deviation of 0.09 g/cm2. Aortae with fatty streaks or fibrous plaques did not cause significant increases of the BMC. The mean deviation for aortae with mild complicated lesions, i.e., those containing smaller amounts of calcium, was within the range of instrument precision.

Early immunoscintigraphic localisation of a mediastinal tumour with indium 111-DTPA CEA-specific F(ab')2 monoclonal antibody fragments (BW 431/31) using second tracer isocontour technique.

A female patient with steadily increasing carcinoembryonic antigen (CEA) serum levels of unknown origin was referred for immunoscintigraphy with indium 111-labelled CEA-specific monoclonal antibody. The procedure revealed a tumour, undetectable by conventional diagnostic methods. Anatomical landmarking using the second tracer isocontour technique allowed the distinction between an intra- or extrapulmonary lesion. Two months later, tumour infiltration along the aortic arch was confirmed by a targeted angio-CT scan. Upon surgery, the diagnosis was definitely established histologically (undifferentiated, solid large cell carcinoma, most probably arising from the bronchus), and staining by CEA-specific immunohistochemistry confirmed the presence of the CEA antigen.

[Immunoscintigraphy using 111In-DTPA-labeled monoclonal antibodies: comparison with ECT and planar scintigraphy]. / Immunszintigraphie mit 111In-DTPA-markierten monoklonalen Antikörpern: Vergleich zwischen ECT und planarer Szintigraphie.

The present study was done in order to examine if the use of 111In-DTPA-labeled MAb fragments in place of 131I-labeled MAb fragments increases the sensitivity of tomographic immunoscintigraphy to reach the level of that of planar imaging techniques. In 11 patients with various primary tumors, local recurrences or metastases [colorectal carcinoma (n = 7), ovarian carcinoma (n = 2), papillary thyroid carcinoma (n = 1), undifferentiated carcinoma of the lung (n = 1)], immunoscintigraphy (IS) was carried out using 111In-DTPA-labeled F(ab')2 fragments of various MAbs (anti-CEA, OC 125, anti-hTG) and planar and tomographic imaging were compared intra-individually. By conventional diagnostic procedures, the presence of a tumor mass was confirmed (transmission computer tomography, ultrasound) or verified (131I whole-body scintigraphy, histology) in all cases. Immunoscintigraphy was positive in 9 out of 11 cases by ECT and in 10 out of 11 cases by planar imaging. When using 111In-labeled MAb fragments, intra-individual comparison of ECT and planar imaging resulted in a similar sensitivity. The increased sensitivity of ECT using this tracer in contrast to 131I-labeled MAb fragments may be attributed to the fact that the physical properties of 111In are much more suitable for the gamma cameras most commonly used (single detector, 3/8'' crystal); using 111In-labeled MAb fragments, count rates sufficient for ECT can be obtained within a reasonable acquisition time. This allows to combine IS with the advantages of ECT regarding tumour localization and prevention of artefacts due to superposition of background.