Infarct final

Several studies have validated the ability of CTP to distinguish between core and penumbra. In one study, Wintermark et al. found that the volumes of early infarcts in CTP CBV maps were highly correlated with volumes of early DWI lesions, whereas volumes of lesions seen in CTP CBF maps were close to those seen in the corresponding MRP MTT maps. In another study, the volume of the CBF abnormahty in an acute-stage infarct was highly correlated with final infarct volume in patients who did not exhibit recanalization after thrombolysis, consistent with extension of infarction into the penumbra. However, in patients who did exhibit recanalization after thrombolysis, final infarct volume was highly correlated with the initial CBV abnormality, consistent with failure of infarcts to extend into the ischemic penumbra. ... 

Lev MH, Segal AZ, Farkas J, Hossain ST, Putman C, Hunter GJ, Budzik R, Harris GJ, Buonanno FS, Ezzeddine MA, Chang Y, Koroshetz WJ, Gonzalez RG, Schwamm LH. Utility of perfusion-weighted CT imaging in acute middle cerebral artery stroke treated with intra-arterial thrombolysis prediction of final infarct volume and clinical outcome. Stroke 2001 32 2021-2028. 

Coutts SB, Lev MH, Eliasziw M, Roccatagliata L, Hill MD, Schwamm LH, Pexman JH, Koroshetz WJ, Hudon ME, Buchan AM, Gonzalez RG, Demchuk AM. ASPECTS on CTA source images versus unenhanced CT added value in predicting final infarct extent and clinical outcome. Stroke 2004 35 2472-2476. 

Additional factors influence the extent of the final infarction. The speed of obstruction may allow collateral arteries to develop, if it occurs gradually (Busch et al. 2003), whereas complete sudden blockade of a major artery by an embolus leaves only some minutes to activate sufficient collateral flow. Hypoxia, hyperglycemia, acidosis, fever, hypotonia, and normal or abnormal variants in vascular anatomy my contribute to the resulting infarction (Hossmann 1999). Basically, the loss of oxygen and... 

Haefelin et al. 1999 Parsons et al. 2001). However, these PI maps significantly overestimate final infarct size (Fig. 3.7) (Parsons et al. 2001). 

Fig. 3.7. Acute DWI and colour PI maps compared to outcome infarct size. Note that the acute CBF lesion is closest to final infarct size and the MTT lesion overestimates final infarct size, suggesting that the MTT map is demonstrating benign oligaemia as well as true penumbra ...

Therefore, most of the final infarct is already irreversibly damaged at the time of the first evaluation... 

Fig.8.6a-d. Various subareas within and outside of the final brain infarction as determined by PET measurements of CBF and flu-mazenil (FMZ) binding on benzodiazepine receptors extension of final infarct as seen on MRI3 weeks post-insult (a) subarea with severely decreased FMZ binding (b) subarea with CBF < 14 ml/100 g/min combination of (a), (b) and (c) showing infarct subareas with decreased FMZ binding and reduced CBF in relation to final infarction. [Reproduced with permission from Heiss et al. (2001)]... 

Ordidge RJ, Van de Vyver FL (1985) Re Separate water and fat MR images. Radiology 157 551-553 Parsons M, Li T, Barber P, Yang Q, Darby D, Desmond P, Tress B, Davis S (2000) Acute hyperglycaemia in stroke leads to increased brain lactate production and greater final infarct size. Stroke 31 2795-2795... 

Perfusion computed tomography prediction of final infarct extent and stroke outcome. Annals of Neurology 58 672-679... 

In the past, in patients without reperfusion treatment, usually exists a clear relationship between the site of artery occlusion, myocardial area at risk and final infarcted area. However, the area at risk with the modem treatment in general diminishes considerably in size. Furthermore, sometimes, even if the culprit artery was reperfused, this has not been sufficient to avoid an extensive infarction (Figure 2.3). 

On the other hand, to know where is the site of occlusion (see Table 4.1) in STE-ACS is important, to decide the need and the urgency to perform a primary PCI. As a consequence of reperfusion treatment (fibrinolytic or PCI) it has been shown that the area at risk during the acute phase is larger than the final infarcted area. 

Puetz V et al (2008) Intracranial thrombus extent predicts clinical outcome, final infarct size and hemorrhagic transformation in ischemic stroke the clot burden score. Int J Stroke 3 230-236. 

An early report from our group indicated that, in the absence of early recanalization, CTA-Sl typically defines minimal final infarct size and, hence, like DWI and thresholded CBF maps (Fig.5.5, 5.6), can be used to identify infarct core in the acute setting [34] (Figs. 5.5, 5.6). Coregistration and subtraction of the conventional, unenhanced CT brain images from the axial, post contrast CTA source images should result in quantitative blood volume maps of the entire brain [15, 27, 70]. CTA-SI subtraction maps, obtained by coregistration and subtraction of the unenhanced head CT... 

In another study, CTA-SI preceding DWI imaging was performed in 48 consecutive patients with clinically suspected stroke, presenting within 12 h of symptom onset (42 patients within 6 h) [24]. CTA-SI and DWI lesion volumes were independent predictors of final infarct volume, and overall sensitivity and specificity for parenchymal stroke detection were 16% and 90% for CTA-SI, and 100% and 100% for DWI, respectively. When cases with initial DWI lesion volume <15 mL (small lacunar and distal infarctions) were excluded from analysis, CTA-SI sensitivity and specificity increased to 95% and 100%, respectively. Although DWI is more sensitive than CTA-SI for parenchymal stroke detection of small lesions (Fig. 5.7), both DWI and CTA-SI are highly accurate predictors of final infarct volume. DWI tends to underestimate final infarct size, whereas CTA-SI more closely approximates final infarct size, despite the bias towards DWI being obtained after the CTA-SI in this cohort of patients with unknown recanalization status. 

Berzin, T, et al., CT perfusion imaging versus MR diffusion weighted imaging prediction of final infarct size in hyperacute stroke [abstract]. Stroke, 2001. 32 p. 317. 

Mehta, N., et al. Prediction of final infarct size in acute stroke using cerebral blood flow/cerebral blood volume mismatch added value of quantitative first pass CT perfusion imaging in successfully treated versus unsuccessfully treated/untreated patients, in Proceedings of the 41st Annual Meeting of the American Society of Neuroradiology. 

Aksoy, F.G., et al. CT perfusion imaging of acute stroke how well do CBV CBE, and MIT maps predict final infarct size in Proceedings of the 86th Scientific Assembly and Annual Meeting of the Radiological Society of North America. 2000. Chicago, IL. 

Chronic infarcts can demonstrate peripheral gyriform T1 high signal from petechial hemorrhage or from laminar necrosis [13] (Fig. 6.7). For the purposes of followup for clinical trials, 30-day FLAIR images have been suggested to be sufficient for final infarct volume [14],... 

Gaudinski, M.R., et al., Establishing final infarct volume stroke lesion evolution past 30 days is insignificant. Stroke, 2008. 39(10) p. 2693-4. 

A number of studies have shown that DW images can be used to predict radiologic outcomes. Several have demonstrated that initial DW images lesion volume correlates well with final infarct volnme on T2 and/or FLAIR images, and slightly nnderestimates it, with correlation coefficients ranging from 0.72 to 0.9 [30, 80-82]. 

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