Thrombus imaging in acute ischaemic stroke using thin-slice unenhanced CT: comparison of conventional sequential CT and helical CT.
OBJECTIVE
Thin-slice helical unenhanced CT can be used for thrombus imaging but increases radiation exposure. Conventional sequential images obtained by multidetector CT can be reconstructed into thin-slice images. The purpose of this study was to evaluate if conventional sequential unenhanced CT images can replace helical unenhanced CT for thrombus imaging.


METHODS
Fifty consecutive patients with acute ischaemic stroke underwent both 5-mm conventional sequential unenhanced CT and helical unenhanced CT. Each of the sequential and helical unenhanced CT images was subsequently reconstructed into four 1.25-mm images. Thrombus volumes and HU were measured semi-automatically using both types of unenhanced CT. Thrombus HU ratio (rHU) was calculated using the HU of the contralateral segment. The intraclass correlation coefficient (ICC) and Bland-Altman plots were used to assess measurement agreement.


RESULTS
The mean rHUs were 1.47 ± 0.17 for sequential unenhanced CT and 1.47 ± 0.18 helical unenhanced CT (P = 0.542). The mean thrombus volumes were 124.25 ± 125.65 mm(3) and 117.84 ± 124.32 mm(3) on sequential and helical unenhanced CT images, respectively (P = 0.063). Measurement agreement between thrombus volumes from the two unenhanced CT images was high (ICC = 0.981).


CONCLUSIONS
Thin-slice unenhanced CT images reconstructed from 5-mm sequential images can replace helical unenhanced CT for thrombus imaging in acute ischaemic stroke.


CONCLUSIONS
• Unenhanced CT is used to evaluate intra-arterial thrombus.                 • Thrombus HU and volume measurements using sequential or helical CT are comparable.                                  • Conventional sequential images can replace helical CT for thrombus imaging.                                  • Radiation dose for thrombus imaging can be reduced using sequential CT.
Department of Radiology and the Research Institute of Radiological Science, Yonsei University College of Medicine, 250 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea.
Sung Soo
SS
Ahn
Eung Yeop
EY
Kim
D000368:Aged; D002343:Carotid Artery, Internal / Q000473:pathology; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007511:Ischemia / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology; D015203:Reproducibility of Results; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology; D013927:Thrombosis / Q000473:pathology*; D036542:Tomography, Spiral Computed / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*