Hyperacute infarct

Fig. 6.3 Arterial enhancement from infarct. T1 weighted postcontrast image shows enhancement of the left MCA vessels in this hyperacute infarct...

Parsons MW, Yang Q, Barber PA, Darby DG, Desmond PM, Gerraty RP, Tress BM, Davis SM. Perfusion magnetic resonance imaging maps in hyperacute stroke relative cerebral blood flow most accurately identifies tissue destined to infarct. Stroke 2001 32 1581-1587. 

Grandin CB, Duprez TP, Smith AM, Mataigne F, Peeters A, Oppenheim C, Cosnard G. Usefulness of magnetic resonance-derived quantitative measurements of cerebral blood flow and volume in prediction of infarct growth in hyperacute stroke. Stroke. 2001 32 1147-1153. 

Because the severity of the vascular lesion contributes to the size of the infarction and thus the clinical outcome, CTA results may be expected to predict outcome. One study assessed the utihty of CTA in 40 patients with acute stroke syndromes and an NIHSS score of >8. The extent of leptomeningeal collaterals on CTA correlated with the outcome from thrombolysis. In 40 hyperacute stroke patients who received rt-PA, those with CTA evidence of poor collaterals, autolysed thrombi, and T lesions showed little benefit from treatment. ... 

Fig. 4. CT and MRI findings in a patient undergoing hypothermia therapy in the hyperacute phase. In this patient, the hypothermia therapy was induced 4 h after embolic occlusion of the right MCA. Only a very small infarction developed in the right temporal cortex.

These repolarisation changes in the extreme right precordial leads are seen only in the hyperacute phase of infarction. Therefore, their absence does not rule out the diagnosis of an RV infarction in the subacute phase. According to our experience,... 

Estimates of hyperacute stroke detection rates for NCCT vary. Early generation CT scanners often failed to detect stroke during the first 48 h after stroke onset [28]. In contrast to this, a 1989 study of 36 patients with MCA infarction reported that 70% of CT examinations obtained within 4 h of stroke onset showed focal decreased attenuation consistent with tissue ischemia [29]. 

Russell E (1997) Diagnosis of hyperacute ischemic infarct with CT key to improved cUnical outcome after intravenous thrombolysis Radiology 205 315-318. 

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. 

Bove, R, et al. CT perfusion imaging improves infarct conspi-cuity in hyperacute stroke. 2001. Ft Lauderdale, FL Stroke. 

Strokes have a characteristic appearance on conventional MRI that varies with infarct age. Temporal evolution of strokes is typically categorized into hyperacute (0-6 h), acute (6-24 h), subacute (24 h to approximately 2 weeks), and chronic stroke (>2 weeks old) (Table 6.1). 

Hyperacute (0-6 h) T2 shows loss of signal flow void FLAIR shows vessel high signal GRE T2 shows blooming susceptibility Occurs within minutes of the infarct... 

Fig. 6.1 Basilar occlusion, (a) The T2 weighted image shows loss of the signal flow void in the basilar artery in this patient with basilar occlusion and hyperacute pontine infarct. No parenchymal abnormality is noted at this early time point, (b) Coronal MIP image from the CT angiogram demonstrates the occlusion as a filling defect (arrow)...

Unlike conventional images, DW images are highly sensitive and specific in the detection of hyperacute and acute infarctions [30, 33-35] (Table 7.3). They are very sensitive to the decreased diffusion of water that occurs early in ischemia, and they have a much higher contrast-to-noise ratio compared with CT and conventional MRI. Reported sensitivities range from 88 to 100%, and reported specificities range from 86 to 100%. A lesion with decreased diffusion highly correlates with infarction. 

Table 7.3 Reliability of DWl for the detection of acute ischemic infarction in hyperacute stroke...

Diffusion-weighted MRI provides the most accurate and reliable estimate of the core infarct in the hyperacute setting (within 6 h of onset)... 

Parsons MW, Pepper EM, Bateman GA et al (2007) Identification of the penumbra and infarct core on hyperacute noncontrast and perfusion CT. Neurology 68 730-736... 

Grandin CB, Duprez TP, Smith AM et al (2002) Which MR-deiived perfusion parameters are the best predictors of infarct growth in hyperacute stroke Comparative study between relative and quantitative measurements. Radiology 223 361-370... 

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