False-negative Diffusion-weighted MR Findings in Acute Ischemic Stroke
Catherine Oppenheim
,a,
Ruxandra Stanescua,
Didier Dormonta,
Sophie Croziera,
Béatrice Marroa,
Yves Samsona,
Gérald Rancurela and
Claude Marsaulta
a From the Departments of Neuroradiology (C.O., R.S., D.D., B.M., C.M.) and Cerebrovascular Emergency (S.C., Y.S., G.R.), Groupe Hospitalier Pitié-Salpêtrière, Paris VI University, Paris, France.
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FIG 1. Case 4: 74-year-old man with sudden left paresthesia.
A–D, Seven hours after the onset of symptoms, FLAIR image (10002/148/1, TI = 2200) (A) shows multiple diffuse areas of periventricular hyperintensity with a small hyperintensity in the right subthalamic area (arrowhead, A and C), whereas DWI (2825/92.6/1) (B) is considered normal. Forty-eight hours after symptom onset, FLAIR image remains unchanged (C) while DWI shows a clear hyperintensity in the right subthalamic area (D), matching clinical presentation.
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FIG 2. Case 6: 61-year-old man with sudden right crural hemiparesis.
A–D, Twenty-two hours after onset of symptoms, FLAIR image (10002/148/1, TI = 2200) (A) shows a small cortical hyperintensity in the left paracentral lobule (arrowhead, A and C), whereas DWI (2825/92.6/1) (B) fails to show a stroke lesion. Four days later, the lesion is still visible on FLAIR image (C), and DWI (D) displays a hyperintensity in the paracentral lobule, consistent with a recent stroke lesion and matching clinical presentation.
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FIG 3. Case 7: 45-year-old man with sudden onset of vertigo, dysmetria, and somnolence.
A–D, On initial MR examination, performed 5.5 hours after onset, MR angiogram (not shown) displayed a partially thrombosed dolichobasilar artery, which was responsible for the mass effect on the brain stem and heterogeneous signal anterior to the pons on FLAIR images. Initial FLAIR image (A) (10002/148/1, TI = 2200) and DWI (B) fail to reveal a stroke lesion. On follow-up MR examination, performed 15 hours after onset, FLAIR image shows a small right-sided brain stem hyperintensity (arrowhead) (C), which is more clearly visible on DWI (D).
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FIG 4. Estimation of the probability of false-negative DWI findings by means of a logistic regression. The probability of false-negative DWI findings is plotted against time for stroke lesions located in the anterior (circles) and posterior (crosses) circulation. For vertebrobasilar stroke lesions (crosses), the probability of false-negative DWI findings diminishes when MR latency increases ( = 0.438, ß = 0.127, P = .04). For lesions located in the anterior circulation (circles), this relation is no longer significant
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