Computerized Axial Tomography with the EMI Scanner

New, Paul F. J.; Scott, William R.; Schnur, James Anthony; Davis, Kenneth R.; Taveras, Juan M.

doi:10.1148/110.1.109

Cited by 278 publications

(43 citation statements)

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“…CT examinations after the administration of intravenous X-ray contrast medium have been suggested as being helpful in differentiating vascular lesions from cerebral tumors in doubtful cases. 15 In the present study only one of 26 cases, a clinically highly probable infarction, showed a definite perifocal increase in X-ray attenuation following injection of the contrast medium. Yock and Marshall have reported marked contrast enhancement in four of twenty patients with infarctions.…”

Section: Discussioncontrasting

confidence: 40%

Diagnostic significance of CSF spectrophotometry and computer tomography in cerebrovascular disease. A comparative study in 231 cases.

Söderström¹

1977

Stroke

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SUMMARY Two hundred and thirty-one patients with cerebrovascular disease were examined by spectrophotometry of the cerebrospinal fluid (CSF) and by computer tomography. Many were followed by repeated examinations. Specific diagnoses -bleeding as opposed to non-hemorrhagic or hemorrhagic infarctions -were indicated in 97% by spectrophotometry and in 65% by CT scan in 201 of the 231 cases (excluding 25 patients with transient ischemic attacks and five patients with cerebral tumors with cerebrovascular onset). Comparison between the two methods revealed agreement in most cases, with disagreement in only a few. The specific diagnosis was generally established on only one examination by both methods: repeated examinations were necessary in only a few cases. The results indicated that a combination of the two complementary methods established the diagnosis in almost all cerebrovascular disorders. This was particularly evident if the examinations were performed 24 hours to 21 days after onset of disease.SPECIFIC DIAGNOSIS of a particular type of cerebrovascular disease is often difficult to establish by conventional clinical examination. Recently, attempts have been made to achieve better diagnostic methods as a prerequisite for rational therapy.In intracranial hemorrhage the hemoglobin, depending upon the biochemical environment, is broken down into various visible and non-visible degeneration products. Nonvisible compounds can be found in cases with subdural and intracerebral hematomas and also in those with minimal or previous bleeding from an aneurysm. The appearance of visible and non-visible xanthochromic compounds with different substance patterns can be demonstrated in cerebrospinal fluid (CSF) by spectrophotometry. "4 "Quantitative" CSF spectrophotometry, with corrections made for traumatic lumbar puncture bleeding 6 and for the influence of serum xanthochromia, 3 ' 4 provides markedly improved diagnosis. High diagnostic accuracy of CSF spectrophotometry has been demonstrated in cerebrovascular diseases, 6 and in subacute and chronic subdural hematomas. 7 Computer tomography (CT scan) also has a recognized diagnostic value in cerebrovascular lesions. With it not only is it possible to differentiate between cerebral infarctions and bleeding but also to determine the exact localization and extent of a lesion. "11 The changes seen on the CT scan are direct and indirect. The direct changes in cerebral infarction are characterized by decreased X-ray attenuation and in hemorrhage by increased X-ray attenuation when compared to normal brain tissue, at least during the first weeks after onset. Occasionally there is decreased as well as increased attenuation within the same region, which has been interpreted as a sign of hemorrhagic infarction. The indirect changes -distortion of anatomical structures normally seen on the CT scan -are most pronounced in extra-and intracerebral hematomas.In previous studies of cerebrovascular diseases, specificFrom the Departments of Neurology and Neuroradiology, Karolinska Hospital, S-...

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Section: Discussioncontrasting

confidence: 40%

Diagnostic significance of CSF spectrophotometry and computer tomography in cerebrovascular disease. A comparative study in 231 cases.

Söderström¹

1977

Stroke

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“…Accuracy of the CT scan in the head and body is high [2] and so is the information yield over competing imaging methods such as cerebral angiography and radionuclide scan [3]. In evaluating the cost effectiveness of the CT scan, long-term outcome requires carefully controlled studies over a long period of time.…”

Section: Discussionmentioning

confidence: 99%

The Use and Misuse of the CT Scan of the Brain

et al. 1992

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Analysis of the results of 897 computerized tomographic (CT) scan examinations of the brain, performed on a wide range of patients over a one-year period was carried out to evaluate the use and possible misuse of the CT scan. During the one-year period, over one-half of the brain scans performed were normal and only 32.7% of CT scans demonstrated a reportable abnormality. The results show a general tendency to request CT scans on patients with little indication for this expensive investigation. This, in return, calls for steps to justify the use of the CT scan facility by means of a medical audit in order to reach optimum efficiency and significant cost effective savings for health institutions in the Kingdom. The computerized axial tomographic (CAT) scan has revolutionized the radiological assessment of the central nervous system (CNS) since its first application in the early 1970s. Over the subsequent decade, it has gradually reduced the need for the more invasive CNS investigations [1]. The subsequent evolution of the second, third, and fourth generation CT scanners with higher resolution and speed has promoted widespread use of computerized axial tomography as a reliable non-invasive tool.In Saudi Arabia, several regional and referral hospitals have acquired CT scanners and put this facility to use. As cost effectiveness has become a central issue in health care delivery, a critical appraisal of the use of CT scan is desirable to justify this facility. The purpose of this study is to assess the use of CT scan, insofar as the brain is concerned, in the Radiology Department of King Fahd Hospital of the University (KFHU). Method and MaterialsThis study covers a 12-month period from April 1986 to March 1987. Table 1 shows the distribution of CT scan orders. A total of 897 cerebral scans were performed during the study period. Forty-six CT scans were missing and were not included in the study. Of the remaining 851 scans, 700 scans were ordered by KFHU staff, and 151 were ordered by staff from other hospitals in the area. Sixty-seven percent of the brain scans were normal and 32.7% showed a reportable abnormality (Figure 1). The abnormalities included cerebral atrophy (22%), intracerebral hemorrhage (19%), infarctions (15%), hydrocephalus (15%), tumor (13%), cerebral edema (11%) which was mostly traumatic, congenital brain anomaly (2.9%), cerebral abscess (1.4%), and foreign body within the brain (0.7%) (Figure 2). Seasonal variation was observed in the CT scan requests with a significant drop in summer which may reflect the general trend of decreased work activity during this hot period of the year.When we further analyzed the abnormalities seen on positive CT scans in order of frequency, we found that patients demonstrating cerebral atrophy on CT scans fell into two groups, the very young and the elderly. In young patients, atrophy is mostly due to postmeningitic atrophic changes, congenital anomalies and in the elderly, changes are related to senile cerebral atrophy (Figure 3). Second in frequency was intracran...

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“…Conventional X-ray micro-CT is a well-established technology first developed for medical purposes (Cormack, 1963;Hounsfield, 1973;New et al, 1974), and subsequently adapted and extended to a wide variety of research fields, including the Earth sciences (Arnold et al, 1983;Conroy and Vannier, 1984;Ketcham and Carlson, 2001). X-ray CT allows for nondestructive 3D visualization and characterization of solids based on differences in the X-ray attenuation coefficients of the sample constituents.…”

Section: Principles Of Conventional Vs Sem Micro-ctmentioning

confidence: 99%

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

Vonlanthen

Rausch

Ketcham

et al. 2015

Journal of Volcanology and Geothermal Research

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The morphology of small volcanic ash particles is fundamental to our understanding of magma fragmentation, and in transport modeling of volcanic plumes and clouds. Until recently, the analysis of 3D features in small objects (b250 μm) was either restricted to extrapolations from 2D approaches, partial stereo-imaging, or CT methods having limited spatial resolution and/or accessibility. In this study, an X-ray computed-tomography technique known as SEM micro-CT, also called 3D X-ray ultramicroscopy (3D XuM), was used to investigate the 3D morphology of small volcanic ash particles (125-250 μm sieve fraction), as well as their vesicle and microcrystal distribution. The samples were selected from four stratigraphically well-established tephra layers of the Meerfelder Maar (West Eifel Volcanic Field, Germany). Resolution tests performed on a Beametr v1 pattern sample along with Monte Carlo simulations of X-ray emission volumes indicated that a spatial resolution of 0.65 μm was obtained for X-ray shadow projections using a standard thermionic SEM and a bulk brass target as X-ray source. Analysis of a smaller volcanic ash particle (64-125 μm sieve fraction) showed that features with volumes N 20 μm 3 (~3.5 μm in diameter) can be successfully reconstructed and quantified. In addition, new functionalities of the Blob3D software were developed to allow the particle shape factors frequently used as input parameters in ash transport and dispersion models to be calculated. This study indicates that SEM micro-CT is very well suited to quantify the various aspects of shape in fine volcanic ash, and potentially also to investigate the 3D morphology and internal structure of any object b 0.1 mm 3 .

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Computerized Axial Tomography with the EMI Scanner

Cited by 278 publications

References 0 publications

Diagnostic significance of CSF spectrophotometry and computer tomography in cerebrovascular disease. A comparative study in 231 cases.

Diagnostic significance of CSF spectrophotometry and computer tomography in cerebrovascular disease. A comparative study in 231 cases.

The Use and Misuse of the CT Scan of the Brain

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

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