We found evidence of a new infarct by CCT in 3.1% of patients with a TIA in our study. This finding was associated with symptoms of TIA lasting more than 1 h, the length to assessment of more than 6 h, the presence of aphasia at admission, and diabetes as a vascular risk factor. In a previous study, the presence of a new infarct was detected by CCT in 4% of patients with a TIA and was associated with the risk of stroke during a period of 90 days after the TIA (Douglas et al. 2003).
In the present study, 17 patients with a TIA (1.1%) suffered a stroke during hospitalization. We also determined that the early short-term risk of stroke was not associated with the evidence of a new infarct on the initial CCT scan. A previous study reported the risk of stroke to be about 4% among patients with a TIA who presented to hospital with a median time of 3 days (Dennis et al. 1990
). The low frequency of stroke in the present study may be explained by early admission, hospitalization of patients, a comprehensive and rapid evaluation including all required diagnostic procedures, and early secondary prophylaxis.
To the best of our knowledge, previous studies have not specifically evaluated the predictors of a new infarct on CCT in patients with a TIA.
Other studies have investigated the relationship between cerebral infarction that is detected by CCT and long-term outcome and suggested that evidence of infarct is correlated with an increase in the risk of recurrent stroke and mortality, but the association between stroke recurrence during hospitalization and infarcts evidence in patients with TIA has not been investigated previously (Evas et al. 1991
; van Swieten et al. 1992
; Gladstone et al. 2004
Obviously, the sensitivity of CCT to detect infarcts is considerably lower than that of other imaging techniques. For example, Fazekas et al. (Fazekas et al. 1996
) detected a new infarct by MRI in 31% of patients with a TIA. Similarly, Prabhakaran et al. (Prabhakaran et al. 2011
), using perfusion computed tomography, found perfusion abnormalities in 33.8% of patients with a TIA. Previous research has also shown that the impact of CCT on visualizing cerebral ischemia in patients with a TIA can be improved with CT perfusion imaging that can provide comprehensive information rapidly (Smith et al. 2003
). In summary, the CCT is less sensitive than MRI and diffusion-weighted imaging (DWI) in identification of new infarct in patients with TIA. In the present study, almost (96.9%) of patients did not show a new infarct on CCT. Several investigations, using DWI, demonstrated the frequency of abnormalities in patients with TIA from 41% to 68% that suggest that DWI is a preferable technique in verifying infarcts in patients with TIA and affords more precise detection of ischemic lesion compared to conventional CCT (Kidwell et al. 1999
; Ay et al. 2002
; Inatomi et al. 2004
; Restrepo et al. 2004
; Oppenheim et al. 2006
Our study has several limitations. The present study did not include the long-term outcome after discharge; the CT findings were abstracted from the radiology reports, which may underestimate the incidence of acute infarction seen on initial CT. The data acquisition was obtained from different hospitals (departments of neurology and internal medicine) without common protocol that could impact the study results, especially in the low rate of stroke risk during hospitalization. However, the work up of TIA follows the uniform recommendation of the German Society of Neurology and German Stroke Society. Another limitation was that the study protocol did not include the findings of the duplex sonography of the arteries in the neck and brain.
Despite these limitations and risks (namely, radiation and iodine contrast exposure) that are associated with CCT (Brenner and Hall 2007
), CCT is performed more frequently than MRI on a daily basis for various reasons. These reasons include the fast acquisition, economical factors, ability to reliably exclude a hemorrhage, availability, and the ease of interpretation of CCT findings compared with other diagnostic brain imaging techniques.