Chapter 11 Intensive Care Unit

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CHAPTER 11 • Intensive Care Unit Imaging

Time Dependence of CT Ischemic Stroke

A

Relative Sensitivity of Diffusion Weighted MRI to Acute Stroke

CT

MRI

B

FIGURE 11-16. A: Time dependence of imaging ischemic stroke by unenhanced CT in patient presenting with new-onset neurologic deficit. The large ischemic zone was not evident on the earlier study. Arrows delineate compromised zone ( Left : upon admission; right : after 36 hours). B: Comparison of near-simultaneously obtained head CT ( left ) and diffusion-weighted MRI ( right ) of a patient with isch- emic (right hemispheric) stroke.

MRI can reveal inflammation and edema (T2 and flair weighting) and perfusion adequacy (diffusion weighting). Despite limitations, the chest CT often provides information not otherwise available. It frequently

reveals a small or loculated pneumothorax in patients when previous CXRs are unrevealing. Chest CT also aids discovery of lung abscess or empyema and usu- ally can differentiate between the two conditions. In patients with empyema and persistent, unexplained