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  • 1
    In: Journal of Neurosurgery, Journal of Neurosurgery Publishing Group (JNSPG), Vol. 95, No. 3 ( 2001-09), p. 450-458
    Abstract: Object. In this study the authors tested the hypothesis that the estimate of the apparent diffusion coefficient (ADC) of water is a reliable pathophysiological index of the viability of ischemic brain tissue. Methods. Cerebral blood flow (CBF) and the cerebral metabolic rates of oxygen and glucose (CMRO 2 and CMR glc , respectively) were measured using positron emission tomography (PET) scanning before and after permanent middle cerebral artery occlusion (MCAO) or reperfusion in pigs. The ADC value, which was measured using diffusion-weighted magnetic resonance (DW MR) imaging was compared with physiological variables obtained by PET scanning and with histological findings. After both permanent MCAO and reperfusion, the decrease in the ADC was significantly correlated with decrease in the CMRO 2 and CMR glc . The infarction coincided with a CMRO 2 threshold of 50% of the value measured on the contralateral side. Thus, an ADC value of 80% or 75% of the contralateral value reflected the CMRO 2 threshold after permanent MCAO or reperfusion, respectively. On DW MR images, lesions with ADC values above 80% of the contralateral value are potentially reversible until 6 hours after MCAO, whereas lesions with ADC values below 75% of the contralateral value are irreversible as early as 2 hours after MCAO. Conclusions. The ADC of water provides a reliable pathophysiological index for tailoring therapy to the condition of individual stroke patients in clinical practice.
    Type of Medium: Online Resource
    ISSN: 0022-3085
    RVK:
    RVK:
    Language: Unknown
    Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
    Publication Date: 2001
    detail.hit.zdb_id: 2026156-1
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  • 2
    In: Journal of Neurosurgery, Journal of Neurosurgery Publishing Group (JNSPG), Vol. 93, No. 4 ( 2000-10), p. 647-657
    Abstract: Object. The authors tested the hypothesis that oxygen metabolism is the key factor linking the long-term viability of ischemic brain tissue to the magnitude of residual blood flow during the first 6 hours following a stroke. Methods. Eleven anesthetized pigs underwent a series of positron emission tomography studies to measure cerebral blood flow (CBF) and metabolism before and for 7 hours after the animals were subjected to permanent middle cerebral artery (MCA) occlusion. The extent of collateral blood supply was assessed using angiography. Abnormal metabolism of the ischemic tissue progressed as a function of time in inverse proportion to the magnitude of residual CBF, and the volume of the infarct grew in inverse proportion to the residual blood supply. Ten hours after occlusion of the MCA, the infarct topographically matched the tissue with a cerebral metabolic rate of oxygen consumption below 50% of values measured on the contralateral side. This was also the threshold for the decline of the oxygen extraction fraction below normal, which was critical for the prediction of nonviable ischemic tissue. Mildly ischemic tissue (CBF 〉 30 ml/100 g/min) did not reach the cerebral metabolic rate of oxygen threshold of viability during the first 6 hours after MCA occlusion; moderately ischemic tissue (CBF 12–30 ml/100 g/ min) reached the threshold of viability in 3 hours; and severely ischemic tissue (CBF 〈 12 ml/100 g/min) remained viable for less than 1 hour. Conclusions. The relationship between the residual CBF and both oxygen metabolism and extraction is critical to the evolution of metabolic deficiency and lesion size after stroke.
    Type of Medium: Online Resource
    ISSN: 0022-3085
    RVK:
    RVK:
    Language: Unknown
    Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
    Publication Date: 2000
    detail.hit.zdb_id: 2026156-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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