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(Stroke. 2003;34:e17.)
© 2003 American Heart Association, Inc.

Letters to the Editor

Correlation of Apparent Diffusion Coefficient and Computed Tomography Density in Acute Ischemic Stroke

Department of Neurosurgery, University of Pécs, Pécs, Hungary

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We read with interest the recent article by Kucinski et al.¹ The authors observed a decrease in the apparent diffusion coefficient (ADC) in diffusion-weighted MR imaging and a corresponding decrease in CT density in patients suffering from acute ischemic stroke of the anterior cerebral circulation. CT measurements showed a continuous linear decrease of 0.4 Hounsfield U/h, whereas the decrease in ADC was almost complete after 1.5 hours. Thus, a different time course was found between the 2 phenomena. A correlation between the decrease in ADC and that of CT density was found. They concluded that the severity of diffusion restriction correlated with net water uptake in acute ischemic stroke.

However, as the authors stated, the underlying pathophysiology and different time courses indicated a common reason rather than a direct causality for both phenomena. The underlying pathophysiology was explained as follows: Changes in CT density are known to correlate linearly with the specific gravity of the nervous tissue, ie, with net water changes in ischemic brain tissue, thus describing the course of water uptake after ischemia. The decrease in ADC in acute ischemia correlates with the reduction in extracellular space caused by a shift of extracellular water into intracellular compartments with consecutive restriction of molecular water diffusion. This water shift results from ion pump failure caused by a severe decrease in oxygen and glucose supply.

The different time courses of ADC and CT values do not support a direct causality between diffusion restriction (brought about by intracellular volume . . . [Full Text of this Article]

Thomas Kucinski, MD; Ole Väterlein; Jens Fiehler, MD; Bernd Eckert, MD Hermann Zeumer, MD

Department of Neuroradiology, University-Hospital Hamburg Eppendorf, Eppendorf, Germany

Volkmar Glauche, MS Joachim Röther, MD

Department of Neurology, University-Hospital Hamburg Eppendorf, Eppendorf, Germany

Ernst Klotz, MS

Siemens Medical Solutions, Erlangen, Germany

Christoph Koch, MD

Department of Neuroradiology, University of Lübeck, Lübeck, Germany