Detection of subarachnoid blood clot and other thin, flat structures by computed tomography

The diagnosis of subarachnoid haemorrhage

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Identification of an anteriorly displaced meniscus in vitro by means of three-dimensional image reconstructions

Computerized tomography has some limitations for diagnosis of internal derangements of the TMJ. The use of three-dimensional image reconstructions of CT data may enhance the diagnostic utility of CT. In a cadaver simulation, three-dimensional imaging was able to demonstrate the location of a displaced meniscus which was not obvious in two-dimensional sections. Location of the meniscus was aided by the use of a "transparency mode" in displaying the data.

Correlation between CT findings and subsequent development of cerebral infarction due to vasospasm in subarachnoid haemorrhage

We have studied the correlations between computed tomograms (CT), clinical severity at the time of onset, and subsequent development of cerebral infarction due to vasospasm in 32 cases with subarachnoid haemorrhage secondary to rupture of cerebral aneurysms. It was found that the clinical severity could be judged by CT as shown by the amount of blood in subarachnoid space. Furthermore, it was possible to predict the subsequent occurrence of cerebral infarction by sequential findings of CT. A Hounsfield number of the high density area over 60 showed good correlation with the development of cerebral infarction.

Computed tomography in the diagnosis of subarachnoid haemorrhage and ruptured aneurysm

One hundred consecutive patients with subarachnoid haemorrhage were investigated by computed tomography (CT) within five days of the bleeding. In 19 cases CT indicated other sources than a ruptured aneurysm, most often a cerebellar haematoma. The other 81 patients did not all undergo angiography. It could be estimated by extrapolation that an aneurysm would be demonstrated in 66 of the 68 patients in whom CST showed extravasated blood in the basal cisterns, and in only five of the remaining 13 patients. In a consecutive series of 50 patients with bleeding from a verified aneurysm, CT showed some extravasated blood in all cases and a haematoma in half of these. In 74% the site of the haemorrhage correctly predicted the site of the ruptured aneurysm. Intravenous contrast medium visualized the aneurysm on CT in 15 of 25 cases; this can improve the identification of the bleeding aneurysm to 88%. Rebleeding occurred in 21 patients, and was obvious in Ct in 19. If available, CT should be the first investigation in patients with first and recurrent subarachnoid haemorrhage.

Computer tomography as the primary radiologic procedure in acute subarachnoid hemorrhage

CT was performed in 149 patients with acute subarachnoid hemorrhage and clinical findings consistent with an aneurysm rupture, and was found informative in most cases when performed within one week after the hemorrhage. CT disclosed in 29 per cent of cases other causes for the hemorrhage than a ruptured aneurysm (intracerebral hemorrhage, tumor, trauma, infarct) and an extensive angiographic evaluation could be omitted. In those patients where the hemorrhage was caused by an aneurysm rupture, the distribution of extravasated blood in the subarachnoid space and the brain parenchyma usually indicated the aneurysm location--angiography could thus be restricted to the proper vessel. These capabilities of CT are sufficient to economically motivate its routine use as the primary investigation in cases with an acute subarachnoid hemorrhage.

Evaluation of subarachnoid hemorrhage and cerebral vasospasm by computed tomography

The CT findings in patients with subarachnoid hemorrhage include visualization of the aneurysm (10% of the cases), subarachnoid, intraventricular, or intracerebral hemorrhage (87% of cases scanned within five days), "ischemic" lucency secondary to spasm (10%), and hydrocephalus (54%).

Value of electroencephalography (EEG) before and after surgery of intracranial aneurysms

Electroencephalographic (EEG) investigations were done in 36 patients with intracranial aneurysms, before and after surgery. Thirty five of them suffered from subarachnoid hemorrhage (SAH). Pre-operatively, there was no correlation between patients' age or sex and localisation of the aneurysm or degree of EEG disturbances. The most frequent finding was a generalised slowing, the degree of which depended on the time from bleeding to EEG. Focal abnormalities were due to spasms of the vessels or intracerebral haematomas. There was a high correlation with neurological deficits. Post-operatively, EEG disturbances became worse in 21 cases. Generalised and focal abnormalities increased. These were due to focal oedema and the operative approach. The EEG could be correlated very well with the findings from other investigative methods (CT scanning, angiography). The EEG, as a functional method, showed very well the whole state of the brain after bleeding and after operation.

Measurements of the partial volume phenomenon

The partial volume phenomenon can produce subtle changes in the reconstructed value of the linear attenuation coefficient which may in turn make the detection of an object more difficult. A model for studying the effects of the partial volume phenomenon is presented along with measurements made on the General Electric CT/T whole body scanner. The results of these measurements indicate that small differences in the linear attenuation coefficient may go unnoticed when the video display format is used exclusively to evaluate the CT image. It is suggested that this display format incorporate profiles of the CT numbers to assist the viewer in the evaluation of the CT scans.

Computed tomography of vertebrobasilar artery aneurysm

Review of computed tomographic as well as clinical and angiographic findings in 19 patients with vertebrobasilar artery aneurysms has revealed that there are two roentgenographically and clinically distinct types of aneurysms: saccular and fusiform. The saccular aneurysms often present with acute subarachnoid hemorrhage that differs in distribution from that seen with anterior circulation aneurysms. Small interpeduncular cisternal hematomas are helpful in localization of these aneurysms. Fusiform aneurysms of the basilar artery frequently present as posterior fossa mass lesions and have a fairly characteristic appearance on computed tomograms.

[Contribution to the diagnosis of cortical atrophy: evaluation of computer tomograms and angiograms of patients over 70 years old (author's transl)]

To find evidence of cortical atrophy, 112 computer tomograms and 40 angiograms of patients above the age of 70 were evaluated. In the CT the width of the interhemispheric and of the sylvian fissure, in the angiograms the distance between the vessels extending into the interhemispheric fissure (anteroposterior view) and the distance between the cortical branches and the inner table (lateral view) were measured. The same measurements were performed in 100 normal computer tomograms and in 100 normal angiograms of patients between 20 and 40 years old. Statistically significant differences could be ascertained between the mean values for the patients over 70 and those for the younger ones, indicating that age-induced cerebral atrophy can be neuroradiologically demonstrated. The radiologic findings, however, do not necessarily correspond to the grade of intellectual impairment in the elderly. Neuropathologic and molecular biological research could bring us closer to the solution of this correlative problem.