Figure 1
Right-sided weakness, hemisensory loss, and homonymous hemianopia
Acute infarct and leukoariasis
The patient presented with a transient ischemic attack. Six days later he developed right-sided weakness, hemisensory loss, and homonymous hemianopia. Echo-planar diffusion MRI was performed using the 'trace' technique (TR=5700, TE=139 msec), providing images with diffusion sensitivity values (b values) of 0.50 sec/mm2, 500 sec/mm2, and 1000 sec/mm2. Also, automated apparent diffusion coefficient (ADC) maps were provided by this sequence.
In ischemia cytotoxic edema develops in the involved region. Cytotoxic edema is associated with restriction of the mobility of water molecules, therefore high signal is observed on true diffusion images (i.e. b=1000 sec/mm2 images), and low signal is seen on corresponding ADC maps with low ADC values. On the other hand, leukoariasis (white matter hyperintensities) is commonly seen in the periventricular regions of elderly, and on ADC maps of diffusion MRI these have high signal, while they may not be apparent on true diffusion (b=1000 sec/mm2) images. Both, acute infarction and leukoariasis have high signal on T2-weighted images, however, their discrimination is possible using the b=500 sec/mm2 , and b=1000 sec/mm2 images, and ADC maps.
References
[1]
Castillo M, Mukherji SK, Isaacs D, Smith JK. Cerebral infarctions: evaluation with single-axis versus trace diffusion-weighted MR imaging.
AJR Am J Roentgenol. 2000 Mar;174(3):853-7. (PMID: 10701638)
[2]
Roh JK, Kang DW, Lee SH, Yoon BW, Chang KH. Significance of acute multiple brain infarction on diffusion-weighted imaging.
Stroke. 2000 Mar;31(3):688-94. (PMID: 10700505)
[3]
Yamada H, Ezuka I, Ikegami Y, Suda T, Kakinuma K, Kanazawa T, Higuchi S. Diffusion-weighted echo planar imaging of acute brain infarction: a preliminary report.
Neurol Med Chir (Tokyo). 1999 Dec;39(13):913-21. (PMID: 10658452)
[4] Altieri M, Metz RJ, Muller C, Maeder P, Meuli R, Bogousslavsky J. Multiple brain infarcts: clinical and neuroimaging patterns using diffusion-weighted magnetic resonance. Eur Neurol. 1999;42(2):76-82. (PMID: 10473978)
[5]
Burdette JH, Elster AD, Ricci PE. Acute cerebral infarction: quantification of spin-density and T2 shine-through phenomena on diffusion-weighted MR images.
Radiology. 1999 Aug;212(2):333-9. (PMID: 10429687)
Case information
| URL: | https://eurorad.org/case/651 |
| DOI: | 10.1594/EURORAD/CASE.651 |
| ISSN: | 1563-4086 |
