Capacities of multidetector spiral computed tomography in the planning and postoperative examination of patients undergoing coronary artery bypass surgery

Multiple investigations show that multidetector spiral computed tomography (MSCT) bypass grafting becomes an alternative to invasive coronary angiography in detecting coronary graft stenoses and occlusions. The investigation retrospectively estimated the patency of aortocoronary and mammary coronary artery anastomoses by MSCT bypass grafting. Examinations were made in 85 (326 anastomoses) patients who had undergone aortocoronary and mammary coronary artery bypass surgery and had MSCT bypass grafting within 3 years after the surgery. In the first year following the surgery, 18 patients with graft stenotic changes, as evidenced by MSCT, underwent intervention coronary angiography, the sensitivity and specificity of which was 100%. The results of clinical and instrumental examinations were also compared with graft incompetence, as shown on MSCT that revealed that MSCT bypass grafting was the only noninvasive technique to evaluate early coronary graft closure both in the absence of clear signs of myocardial ischemia according to the data of exercise tests and in the presence of recurrent angina pectoris.     

Endocranial capacity of the bodo cranium determined from three-dimensional computed tomography

The 600,000-year-old cranium from Bodo, Ethiopia, is the oldest and most complete early Middle Pleistocene hominid skull from Africa. "Virtual endocast" models created by three-dimensional computed tomography (CT) techniques indicate an endocranial capacity of about 1,250 cc for this cranium (with a reasonable range between approximately 1,200-1,325 cc, depending on how missing portions of the basicranial region are reconstructed). From these determinations, several important implications emerge concerning current interpretations of "tempo and mode" in early hominid brain evolution: 1) already by the early Middle Pleistocene, at least one African hominid species, Homo heidelbergensis, had reached an endocranial capacity within the normal range of modern humans; 2) in spite of its large endocranial capacity, estimates of Bodo's encephalization quotient fall below those found in a large sample of Homo sapiens (both fossil and recent) and Neandertals; and 3) the greatest burst of brain expansion in the Homo lineage may not have been in the last several hundred thousand years, but rather much earlier in the Lower to early Middle Pleistocene.     

Automated analysis of three-dimensional xylem networks using high-resolution computed tomography

Connections between xylem vessels represent important links in the vascular network, but the complexity of three-dimensional (3D) organization has been difficult to access. This study describes the development of a custom software package called TANAX (Tomography-derived Automated Network Analysis of Xylem) that automatically extracts vessel dimensions and the distribution of intervessel connections from high-resolution computed tomography scans of grapevine (Vitis vinifera) stems, although the method could be applied to other species. Manual and automated analyses of vessel networks yielded similar results, with the automated method generating orders of magnitude more data in a fraction of the time. In 4.5-mm-long internode sections, all vessels and all intervessel connections among 115 vessels were located, and the connections were analyzed for their radial distribution, orientation, and predicted shared wall area. Intervessel connections were more frequent in lateral than in dorsal/ventral zones. The TANAX-reconstructed network, in combination with commercial software, was used to visualize vessel networks in 3D. The 3D volume renderings of vessel networks were freely rotated for observation from any angle, and the 4.5?μm virtual serial sections were capable of being viewed in any plane, revealing aspects of vessel organization not possible with traditional serial sections.     

Craniofacial deformity in patients with uncorrected congenital muscular torticollis: an assessment from three-dimensional computed tomography imaging

Congenital muscular torticollis is caused by idiopathic fibrosis of the sternocleidomastoid muscle that restricts movement and pulls the head toward the involved side. Deformation of the craniofacial skeleton will develop if the restriction is not released and result in aesthetic and functional problems. The purpose of this study was to use three-dimensional computed tomography imaging for qualitative and quantitative evaluation of the craniofacial deformity in a series of patients with uncorrected congenital muscular torticollis, and to assess age as a precipitating factor for severity of the deformity. A total of 14 patients from 1 month to 24 years of age were included. The skull images were rotated into standard orientation and reconfigured for evaluation of the cranium, endocranial base, and facial skeletal structures. The midlines of cranial base and facial bone, angle of midline deviation, width of each hemicranium and hemiface, and the orbital index were defined and measured. The results showed that the cranium and cranial base deformation took place as early as in infant stage, with the most prominent change occurring in the posterior cranial fossa. Facial bone asymmetry started to appear after 5 years of age, at which time the mandibular and occlusal abnormalities were observed. The deformity of the orbits and maxilla occurred at an older age, characterized by the deviation and decreased vertical height on the affected side. The severity of the observed deformities increased with age. The angle of midline deviation was 2.48 +/- 1.68 degrees in the cranial base and 3.26 +/- 3.28 degrees on the facial bone. Both of the midline deviations were significantly correlated with age. Compared with the contralateral side, the width of the ipsilateral posterior hemicranium was longer (54.36 +/- 6.72 mm versus 50.81 +/- 6.55 mm), and the width of the ipsilateral lower hemiface was shorter (35.30 +/- 7.27 mm versus 43.49 +/- 11.34 mm). Both differences were statistically significant. Measurement of the orbital index demonstrated a significantly flatter orbit on the ipsilateral side (89.48 +/- 0.11 versus 92.74 +/- 0.08). This study showed that the cranium and cranial base deformity occurred early in patients with uncorrected torticollis, while the facial bone deformity occurred in childhood stage. The cranial and facial deformity became more severe with age. Early release of the muscle restriction is advised to prevent craniofacial deformation.     

Three-dimensional computed tomography of the mummy Wenuhotep

Computed tomography allows cross-sectional imaging of anthropological as well as clinical subjects. Recently, technical innovations have made three-dimensional reconstruction of these images feasible. We performed two-dimensional and three-dimensional computed tomography of a Late Period Egyptian mummy to reexamine findings seen on previous radiographic studies and to evaluate the usefulness of these techniques in paleopathology. Two-dimensional images provided excellent anatomic detail. There was graphic depiction of the mummification process that corroborated information previously obtained from Egyptological studies. Three-dimensional reconstruction provided images of facial features as if the mummy had been unwrapped. Three-dimensional computed tomography is a useful method of nondestructively evaluating paleopathological remains, and it may yield information not obtainable by any other means.     

Effect of diagnostic cone-beam computed tomography protocols on image quality,patient dose,and lesion detection

ObjectiveTo evaluate the effect of cone-beam computed tomography (CBCT) image acquisition protocols on image quality, lesion detection, delineation, and patient dose.Methods100-patients and a CTDI phantom combined with an electron density phantom were examined using four different CBCT-image acquisition protocols during image-guided transarterial chemoembolization (TACE). Protocol-1 (time: 6 s, tube rotation: 360°), protocol-2 (5 s, 300°), protocol-3 (4 s, 240°) and protocol-4 (3 s, 180°) were used. The protocols were first investigated using a phantom. The protocols that were found to be clinically appropriate in terms of image quality and radiation dose were then assessed on patients. A higher radiation dose and/or a poor image quality were inappropriate for the patient imaging. Patient dose (patient-entrance dose and dose-area product), image quality (Hounsfield Unit, noise, signal-to-noise ratio and contrast-to-noise ratio), and lesion delineation (tumor-liver contrast) were assessed and compared using appropriate statistical tests. Lesion detectability, sensitivity, and predictive values were estimated for CBCT-image data using pre-treatment patient magnetic resonance imaging.ResultsThe estimated patient dose showed no statistical significance (p > 0.05) between protocols-2 and -3; the assessed image quality between these protocols manifested insignificant difference (p > 0.05). Two other phantom protocols were not considered for patient imaging due to significantly higher dose (protocols-1) and poor image quality (protocol-4). Lesion delineation and detection were insignificant (p > 0.05) between protocols-2 and -3. Lesion sensitivities generated were 81–89% (protocol-2) and 81–85% (protocol-3) for different lesion types.ConclusionData acquisition using protocols-2 and -3 provided good image quality, lesion detection and delineation with acceptable patient dose during CBCT-imaging mainly due to similar frame numbers acquired.     

Feasibility and accuracy of tissue characterization with dual source computed tomography

PurposeTo evaluate the feasibility and accuracy of a model for tissue characterization with dual source computed tomography (DSCT).Methods and MaterialsA model for tissue characterization in CT was used with a parameterization of linear attenuation coefficients. Sixteen chemical substances with effective atomic numbers between 5.21 and 13.08 and electron densities between 2.20 and 4.12 x10²³ electrons/cm³ were scanned at energies of 80 and 140 kV on a DSCT. From the reconstructed dual energy data sets, effective atomic numbers and electron densities of the substances were calculated.ResultsOur presented model using DSCT approximated the effective atomic numbers and effective electron densities of 16 substances very well. The measured effective atomic numbers deviated 3.4 ± 6.8% (R² = 0.994) from theoretical effective atomic numbers. In addition, measured effective electron densities deviated ?0.6 ± 2.2% (R² = 0.999) from theoretical effective electron densities.ConclusionEffective atomic numbers and effective electron densities can be determined with a high accuracy with DSCT. Therefore the model can be of potential benefit for clinical applications of quantitative tissue characterization with DSCT.     

Magnetic resonance tomography, computed tomography and ultrasonic diagnosis of hemangiomas of the liver

The paper is concerned with the potentialities of modern radiation methods in the diagnosis of liver hemangiomas. USI, CT, angiography and MR-tomography (MRT) were used for investigation of 64 patients with liver hemangiomas. The diagnostic potentialities and the role of each of the above methods in the diagnostic algorithm in liver hemangiomas were studied. The results of the investigation have shown that MRT possesses a higher informative value than USI and CT in the diagnosis of liver hemangiomas and can even replace angiography in the verification of diagnosis.     

3D analysis of anatomical reactions in conifers after mechanical wounding: first qualitative insights from X-ray computed tomography

The ability of trees to recover from damage beyond the last-formed periderm as well as the drivers and nature of associated wound reactions have been studied for more than two centuries using macroscopic (desiccation, aeration or discoloration of wood) and microscopic approaches (anatomical and chemical reactions). However, no studies currently exist which address large-scale macroscopic and microscopic reactions surrounding wounds in the tangential, axial, and radial directions over continuous segments of tree stems. This note explores the potential of 3D X-ray computed tomography in assessing effects of wounding under natural conditions in European conifers (Abies alba, Larix decidua, Picea abies). We present results from a pilot study and qualitatively evaluate the potential of the approach used in assessing and illustrating the formation and spread of de-differentiated xylem parenchyma cells, xylem decay compartmentalization, resin ducts, and stabilizing compression wood cells.     

Noninvasive three-dimensional viewing of the motion and anatomical structure of the heart, lungs, and circulatory system by high speed computerized X-ray tomography.

A new generation X-ray computerized tomography system now under construction, the Dynamic Spatial Reconstructor (DSR), will record 1680 multiple view X-ray video images of the chest or other segments of the body per second. This allows com0utation of stop-action and 60-per-second instant replay motion pictures of the dynamic three-dimensional changes in shape and dimensions of the full anatomic extents of the internal and external surfaces of the heart chambers or the vascular anatomy and circulatory dynamics in any region of the body. Current commercially available scanners require one or more seconds per cross-sectional scan and lack the synchronous volumetric scanning capabilities of the DSR. These capabilities allow nondestructive mathematical selection and removal of any subvolume of interest from a reconstructed volume. The associated abilities to "zoom in" and "section" this subvolume so as to examine its structure and physiologic function in detail allow direct visualization of the internal anatomy and function of organ systems within the body. These capabilities of "noninvasive numerical biopsy" and "vivisection" have heretofore been the preserve of pathologists at autopsy or surgeons at the operating table. Possible future availability of these techniques to the practicing internist carries promise of revolutionary improvements in clinical diagnosis and treatment of the myriad of disease processes, including cancer, which may affect the heart, lungs, vascular anatomy or circulatory dynamics in any region of the body.