<prompt> Brain infarct is detected at the earliest byNCCTCECTX rayDiffusion weighted MRI  <response>: Diffusion weighted imaging DWI is the most sensitive sequence for stroke imaging, becomes positive within minutes in 95 casesDiffusion-negative acute strokes may be Small lacunar infarcts, Brainstem lesions, Rapid clot lysisrecanalization, and Transientfluctuating hypoperfusionDiffusion tensor imaging DTI is even more sensitive than DWI, especially for pontine and medullary lesionsOn CT Early signs of ischemiaHypo attenuating brain tissueObscuration of the lentiform nucleusInsular Ribbon signDense MCA signHemorrhagic infarctsOsborns Brain: Imaging, Pathology, and Anatomy, page 189,190,191 