Clinical Features of Patients with False Negative Diffusion-weighted MR Findings in Acute Ischemic Stroke

Nam, Koong Ihn; Han, Kap Su; Cho, Han Jin; Moon, Sung Woo; Choi, Sung Hyuk; Lee, Byung Chan

Abstract

PURPOSE
Diffusion-weighted magnetic resonance (MR) image (DWI) has advantages for the assessment of acute stroke. However, false negative DWI findings in acute ischemic stroke have been reported. Our purpose was to estimate the rate of initial false negative DWI studies in acute ischemic stroke patients and to identify characteristics of false negative DWI stroke patients.
METHODS
In this retrospective study from January 2010 to June 2011, acute ischemic stroke patients (within 6 hours after stroke onset) were enrolled. A total of 56 patients were included in this study. Cases with negative initial DWI findings, with an ischemic lesion visible on follow-up MR studies, were analyzed for times between the onset of symptoms and initial DWI, National Institute of Health Stroke Scale (NIHSS), and the location of the ischemic stroke lesion.
RESULTS
We found seven cases (12.5%) of false negative initial DWI studies. The initial false negative DWI group had a significantly shorter time from the onset of symptoms to the initial DWI compared to the initial positive DWI group (p=0.011). The false negative group had a lower NIHSS without significance (p=0.091).
CONCLUSION
A false-negative DWI study is not uncommon in the assessment of acute ischemic stroke. Thus, patients suspected of having a stroke should not be ruled out on the basis of a negative DWI, especially a suspected low NIHSS, for an early onset of symptoms.