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NEUROLOCIC/HEAD AND NECK IMAGING 1285

NEUROLOCIC/HEAD AND NECK IMAGING 1285

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TEACHING PO INTS

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CME

Sec to w ca. rsna . otgieducation :rg_cnie. htwl

LEARNING

OB)ECTIVES

After compkluig ihis joiartłal-based CME acńuity, partie tpa uts to iii be a Uc to:

■    E5xplain how to determine the rcla-tivc age of an isch-cmic strokc on the fcasis of MR imaging findings.

■    Dcscribc the in> portancc and liniita-tions of FLAIR MR iniaging in dating acutc ischcmic strokc.

■    Discuss the cur-rent tinie Windows and guidclincs for administering thrombolytic and ncurointcrvcntional thcrapics.

INYITED

Sequence-specific MR Imaging Findings That Are Useful in Dating Ischemic Stroke¹

Laura M. Allen, MD •Anton N. Hasso, MD • Jas on Handzoerker, MD Hatned Far id, MD

Patients may present to the hospital at various times after an ischemic stroke. Many present weeks after a neurologie deficit has occurred, as is often the case with elderly patients and diose in a nursing home. The abi li ty to determine the age of an ischemic stroke provides useful clinical information for die patient, his or her family, and die medical team. Many times, perfusion imaging is not performed, and pulse se-ąuence-specific magnetic resonance (MR) imaging findings may help determine the age of die infaret. The findings seen at apparent diffusion coefficient mapping and diffusion-weighted, fluid-attenuated imersion recovery (FLAIR) and unenhanced and contrast material-enhanced Tl - andT2-weiglited gradient-echo and suscepdbilin-weighted MR imaging may help determine die relative age of a cerebral infaret.

Strokes may be classified and dated as early hyperacute, late hyperacute, acute, subacute, or chronic. Recent data indicate diat in many patients with restricted diffusion and no change on FLAIR images, it is morę likely dian was initially diouglit that the stroke is less dian 6 hours old. The time window to administer intravenous tissue plasminogen activa-tor is currently 4.5 hours from die time when the patient was last seen to be normalj and for anterior circulation strokes, die time window for administering intraarterial tissue plasminogen activator is 6 hours from when die patient was last seen to be normal. For this reason, accurate dating is important in patients with ischemic stroke.