Computed Tomography and Radionuclide Imaging in the Evaluation of Ischemic Stroke

SUMMARY Twenty patients with stroke were studied for cerebral blood perfusion abnormalities using N-isopropyl 1-123 p-iodoamphetamine (IMP) and rotating dual gamma camera emission computed tomography (ECT). After a single scan, multiple transverse, coronal and sagittal section images were reconstructed with a minicomputer. In eighteen patients, we determined the values of regional cerebral blood flow (rCBF) in the region of interest using an image. Transmission computed tomography (CT) studies were also performed on the same day. ECT showed cerebral perfusion abnormalities in all cases, while CT showed abnormalities in only 10 cases. This technique seems to be useful for evaluating the rCBF in the deep brain.

Section: Discussionmentioning

confidence: 99%

Cerebral blood flow studies using N-isopropyl I-123 p-iodoamphetamine.

Kobayashi¹,

Hayashi²,

Kawano³

et al. 1985

“…Campbell et al 10 have noted that early scans may be negative with a peak detection rate between the eighth and eleventh day. This is unlikely to be the explanation in our patients in that all of the normal scans were carried out at least 5 days after the acute episode.…”

Section: Discussionmentioning

confidence: 99%

Computed tomography in patients presenting with lacunar syndromes.

Nelson¹,

Pullicino²,

Kendall³

et al. 1980

123

SUMMARY Of 312 stroke patients who bad a CT scan, 37 had presented clinically with a lacunar syndrome. In 18 of the 37, lacunar sized infarcts were demonstrated on the scan, 13 had normal scans and in 6 large infarcts were found. Of these 6, 5 had a pure motor hemiplegia and one a pure sensory stroke.Clinical evidence and anglography revealed a potential and treatable source of eraboli in both the lacunar sized and the large infarcts. Two conclusions are drawn: a clinical lacunar syndrome may be associated with a large infarct; demonstration of a lacunar infarct on CT scan does not exdude the need for angiography in appropriate cases to discover a possible source of eraboli.Stroke, Vo! 11, No. 3, 1980 THE DETERMINATION of the anatomical localization and pathology of cerebral infarctions is of more than academic importance. Fisher, 1 Caplan 2 and others have emphasized that patients with lacunes have a good prognosis and should not be submitted to potentially hazardous investigations and needless therapy.The word lacune is a neuropathological term referring to a small area of softening usually situated in the distribution of the basal perforating arteries. Such lesions may, however, occur elsewhere such as, for example, in the brain stem. The pathological features of lacunes have been studied by Fisher who also reviewed the history.1 '' In addition, he has delineated a number of clinical syndromes 4 " 7 which, by subsequent autopsy examination of the brain, he identified with lacunes in specific sites. Thus the term lacunar infarct or lacunar stroke has come into use as a clinical term, the pathological and etiological basis being assumed from the clinical features. These include a specific neurological deficit, the frequent association of arterial hypertension and marked tendency to recovery. The Harvard Stroke Registry project, for example, includes lacunar stroke among the cerebrovascular conditions to be recognized. ' The clinical diagnosis of lacunar stroke could only be confirmed if there were some imaging method which would consistently demonstrate the pathological lesion. Computed tomography (CT) can show the larger lacunes. The value of CT in recognizing the smaller ones is limited and varies with the scanning system. It plays an important part in the diagnostic study of strokes, mainly by excluding other types of pathology and it will reveal most infarcts which are too large or superficial to be termed lacunar.The present study was undertaken to determine the CT scan findings in patients presenting with the clinical syndromes which have been considered to be diagnostic of lacunar infarction. MethodsAmong 312 stroke patients who had been studied by CT scanning at the National Hospital, London, on EMI 1010 or 5005 machines, there were 37 who presented with one of 4 syndromes known to be associated with lacunar infarction. All the patients underwent detailed neurological examination during the acute stage of their stroke and fitted into one of the 4 following groups;1. Pure motor hemiplegia (involvin...

“…The value of contrast enhancement was calculated from the difference of the mean EMI number of the two scans. The intensity of contrast enhancement was graded as marked (numeric value >20), moderate (value [11][12][13][14][15][16][17][18][19], mild (value 4-10), and none (numeric value <3). A possible mass effect on the CT image of each infarcted brain was recorded on the basis of midline shift and local compression due to brain edema.…”

Section: Methodsmentioning

confidence: 99%

“…1, who had temporary cerebral ischemia, the value of contrast enhancement in the area of cerebral infarction increased between the 2nd and 3rd scan, from 42. 17 …”

Section: Assessment Of Contrast Extravasationmentioning

confidence: 99%

CT enhancement after prolonged high-dose contrast infusion in the early stage of cerebral infarction.

Ito¹,

Tomita²,

Kito³

et al. 1986

SUMMARY To demonstrate the BBB break-down on the CT image in the acute stage of cerebral infarction, a 3 hour continuous drip infusion of 200 ml of meglumine amidtrizoate, rather than the conventional bolus Injection, was used. In this study, 22 examinations were carried out in 18 patients in whom cerebral infarction due to temporary or permanent obstruction of the cerebral artery was diagnosed by CT and angiography on admission. With each examination, the first CT was obtained prior to contrast infusion, and second immediately after the end of 3 hours of continuous contrast infusion. The EMI number was calculated at 3 regions of interest in the infarction. Within 3 days after stroke episode, 4 out of 5 patients with temporary vascular obstruction demonstrated enhancement, as well as 6 out of 9 patients with permanent vascular obstruction. Between 4 and 14 days after the stroke episode, all of 8 patients showed enhancement.To further clarify the extravasation of the contrast medium during the first 3 days of a cerebral infarction, a third CT scan was performed 3-hrs after finishing the contrast infusion in 4 patients. In these latter patients, blood was sampled at the time of each of the 3 CT series. The EMI number of the blood samples was also measured. In all 4 patients, the Gado's tissue-blood ratio (the EMI number of the CT lesion divided by that of the blood sample) was higher than 17.2% hi the second, and higher than 54.7% in the third CT scan. Thus break-down of the BBB which was demonstrated by prolonged contrast infusion is an earlier event hi human cerebral infarction than is usually accepted. Stroke Vol 17, No 3, 1986IN STROKE PATIENTS, CT enhancement of the infarcted tissue upon ordinary contrast bolus injection occurs 2-4 weeks after the episode.1 " 8 However, a hypodense mass effect due to ischemic brain edema develops within a week of the episode 5 "* 18 "" and first appears 2-3 days after the occurrence of the stroke. On the other hand, in the experimental ischemic model, blood-brain barrier (BBB) damage due to ischemic vascular change usually occurs in an earlier stage after cerebral ischemia than CT enhancement of the ischemic human brain. In animal models, these findings are particularly pronounced following restoration of the blood flow after experimental temporary cerebral ischemia. 1213 Our animal experiments also suggested that extravasation of markers such as RISA and HRP through the BBB damaged by ischemic insult is a gradual process. Therefore, we asked whether in human cerebral infarction, the BBB change could be demonstrated earlier than is usually accepted, 14 if a high blood concentration of contrast medium could be maintained for a prolonged period of time. To answer this question, we employed prolonged infusion of contrast medium rather than conventional bolus injection to study CT enhancement during the acute phase of human cerebral infarction. Potential risk of using a high dose of contrast materials in acute stroke is discussed. Materials and MethodsTwenty-two examinations wer...