What is expected of CT in the evaluation of stroke?

Mass Effect and Atrophy after Stroke

Cerebral edema, resolution of edema, and subsequent development of cerebral atrophy were studied prospectively in 83 patients with ischemic stroke with CT 3 days, 2 weeks, and 6 months post-stroke. Nineteen patients had large (diameter > 3 cm), 25 medium sized (diameter ≥ 1.5 ≤ 3 cm), and 15 lacunar infarcts (diameter < 1.5 cm). In 24 patients no infarcts were seen. Changes of Evans' ratio (ER), septum-caudate distance (S/C), and width of widest cortical sulci (SuW) were taken as markers of mass effect/atrophy. These parameters were within normal limits in most cases. However, when all CT scans performed in each patient were compared, changes of ER, S/C, and SuW became apparent as evidence of mass effect and subsequent atrophy development. Mass effect occurred in 81 percent and atrophy in 58 percent of patients with large infarcts. In patients with medium sized infarcts, mass effect occurred in 38 percent and atrophy in 45 percent.

Infarct topography and hemiparesis profiles with cerebral convexity infarction: the Stroke Data Bank

For the 183 of 1276 patients in the NINDS Stroke Data Bank with convexity infarction in the middle cerebral artery territory, the size of the infarct did not differ between the two sides but the location of the main site of the infarct differed: on the left side, it was centred in the inferior parietal region, and was mid-frontal on the right. There was a good correlation between infarct size and weakness severity whether estimated by overall motor function on one side, arm, or hand alone. There was a poor correlation, however, for lesion location (lower third, middle third or upper third on either side of the Rolandic fissure) and any of the specific syndromes of focal weakness, no two cases sharing the same lesion for the same syndrome and several cases sharing the same lesion with a different syndrome. The findings indicated a difference in weakness syndromes between the two hemispheres and great individual variation of the acute syndrome caused by a given site of focal infarction along the Rolandic convexity. These variations may explain some of the difficulties showing effects of a given therapeutic agent in studies of acute ischaemic stroke. Large sample sizes will be required for the reliable assessment of any treatment using currently popular clinical stroke scales.

Computed tomography in prognostic stroke evaluation

BACKGROUND AND PURPOSE

Computed tomography is now routinely used in many hospitals to investigate cerebrovascular disease. The purpose of our prospective study was to determine whether cranial computed tomography in connection with neurological assessment was useful in prognostic evaluation of survival after acute stroke.

METHODS

Two-hundred forty-five consecutive stroke patients were included in the project during a 1-year period. Each had a detailed neurological assessment 24-72 hours after stroke onset and underwent cranial computed tomography without intravenous contrast injection within the first week after admission. The lesions were divided according to neuroanatomic regions. In the statistical analyses we used a multiple logistic regression model with survival/death as the binary variable.

RESULTS

Computed tomography showed 76% of the patients had infarcts, 11% had hemorrhages, and 13% had no acute lesion. Forty-three patients had more than one acute lesion, and 57 had one or more old infarctions. The temporal, parietal, and frontal regions and the basal ganglia were most often affected.

CONCLUSIONS

We conclude that age, level of consciousness, and involvement of the temporal lobe on computed tomography were factors of prognostic significance regarding survival in the acute phase.

Positron emission tomography in the investigation of neuropsychiatric disorders: update and comparison with magnetic resonance imaging and computerized tomography

In many neuropsychiatric disorders, PET imaging offers functional insights unavailable from anatomic imaging alone. Functional deficits may be more extensive than structural findings would indicate, may occur before the detection of anatomic changes, or may even occur in the absence of any structural lesions. We contrast the current role of PET with that of MRI and CT in the investigation of neuropsychiatric disorders including stroke, tumor, head trauma, epilepsy, schizophrenia, movement disorders, normal aging and dementia.

Correlation of clinical and computed tomographic findings in stroke patients

We evaluated the correlation between clinical features and computed tomographic findings in a prospective study of 1,191 consecutive patients with acute cerebrovascular disease seen during 1 year. In the 386 patients in whom symptoms and signs initially suggested a cerebrovascular disorder, computed tomography revealed a relevant lesion in 154 (hemorrhagic in 52 [33.8%], ischemic in 102 [66.2%]) and a significant nonstroke abnormality in 14 (3.1%). Among the remaining 805 patients with symptoms and signs suggesting some central nervous system disorder other than stroke, computed tomography revealed a cerebrovascular lesion in 38 (4.7%); 35 of these lesions were ischemic. The computed tomographic findings was compatible with the final clinical diagnosis in 192 (84.2%) of the 228 patients with lesions. In the entire sample of 1,191 patients, a cerebrovascular disorder would have been missed in 38 (3.2%) without computed tomography. On the other hand, computed tomography failed to visualize a cerebrovascular lesion in 40 patients in whom such a lesion was clinically obvious. Our results emphasize that both careful neurologic assessment and a policy of early computed tomography are of crucial importance in the diagnosis of stroke and for therapeutic considerations.

The "dense artery sign"--major cerebral artery thromboembolism demonstrated by computed tomography

A 4 years review of high resolution thin slice (3-5 mm) computed tomography performed within 24 h after cerebral infarction revealed increased density in a major cerebral artery segment in 28 patients. Arteries affected were the vertebral and basilar artery in 6 and 8 patients, the sphenoid course of the middle cerebral artery in 13 cases and the extracranial internal carotid artery in 1 patient. In 35.7% of cases the so called "dense artery sign" provided earliest evidence of the ensuing infarction documented by CT controls in most patients. Angiography carried out in 8 patients, density calculations in the course of the affected vessel and resolution of the increased density on subsequent CT examinations suggest thrombembolism as the most likely etiology. In the clinical setting of acute stroke increased artery density encompassing the entire vessel diameter may serve as an early indicator of major cerebral artery occlusion and prompt angiographic investigation of a lesion potentially amenable to lysis.

Value of contrast enhanced CT scanning in the non-trauma emergency room patient

To determine the value of performing contrast CT in addition to non-contrast CT in the evaluation of acute non-traumatic central nervous system disorders, we retrospectively reviewed 322 cases originating from the emergency room at our institution. The most common indication for scanning was seizure activity (34% of total), followed by headache (30%), focal neurological deficit (10%), and altered mental status (8%). 75% of the non-contrast scans were normal. The contrast-enhanced scan revealed abnormalities not evident on the non-contrast scan in only three of these cases, and the information did not alter patient management. We conclude that in the acute setting, if a non-contrast CT is normal, a contrast study is usually unnecessary. Therefore, given the additional risks of contrast infusion, the contrast study, if needed, is generally best obtained at a later date, after more careful evaluation of the patient's history and medical records. If the non-contrast CT scan is abnormal, a contrast enhanced CT scan may be beneficial, but, again, is often not needed to direct acute patient management.