<p><b><i>Background:</i></b> Thrombus visualization in patients with
acute ischemic stroke has been detected and reported using various
imaging modalities. T1-weighted imaging (T1-WI) can depict thrombi as
hyperintense signals within vessels. Moreover, in addition to thrombi,
T1-WI hyperintensities in arteries may suggest arterial dissection.
However, the frequency of and factors related to the T1-hyperintense
vessel sign (T1-HVS) are not fully known. The aim of this study was to
clarify the prevalence of and related factors for the T1-HVS in patients
with acute ischemic stroke. <b><i>Methods:</i></b> From September 2014
through December 2015, consecutive acute ischemic stroke patients who
were admitted to our stroke unit within 7 days from symptom onset were
retrospectively recruited from the prospective registry. A T1-HVS was
defined as the presence of a hyperintense signal, with intensity higher
than surrounding brain, within the vessel lumen. Moreover, T1-HVSs were
separated into filled T1-HVSs (hyperintensity fills whole vessel lumen)
and non-filled T1-HVSs. The frequency of the T1-HVS and the timing of
emersion and the relationship between the presence of the T1-HVS and
arterial occlusion were assessed. <b><i>Results:</i></b> A total of 399
patients (139 women; median age 73 years; National Institutes of Health
Stroke Scale score 3) were enrolled in the present study. Of these, 327
(82%) patients had T1-WI on admission. Two hundred and sixty-seven (67%)
subjects had at least one follow-up T1-WI (median 6 days after
admission), and 134 (34%) cases had ≥2 follow-up T1-WI examinations. The
T1-HVS was observed in 18 patients during admission; therefore, the
frequency of the T1-HVS in acute ischemic stroke patients was 4.5% (95%
CI 2.5-6.5%). All but one (94%) of the T1-HVSs were first observed on
follow-up imaging, and the median number of days from onset to T1-HVS
appearance was 9. For patients having initial major artery occlusion and
follow-up MRI (<i>n</i> = 95), sensitivity and specificity of the
T1-HVS for persistent arterial occlusion on follow-up MR angiography
were 22 and 100%, respectively. T1-HVS persisted for a few months and
then normalized. Although there were no significant differences between
filled and non-filled T1-HVS, more patients with non-filled T1-HVS had
arterial dissection (43%) than those with filled T1-HVS (9%, <i>p</i> = 0.245). <b><i>Conclusion:</i></b>
The T1-HVS was observed in 4.5% of acute ischemic stroke patients.
T1-HVSs appeared in the subacute phase in arteries with persistent
occlusion and remained for a few months.</p
