Comparison of 64-row and 16-row multidetector CT in the perfusion CT evaluation of acute ischemic stroke patients receiving intravenous thrombolytic therapy.

INTRODUCTION: Perfusion computed tomography (PCT) is increasingly performed in multimodal CT evaluation of acute ischemic stroke. We compared the technical quality of perfusion studies performed with a 16-row and a 64-row scanner and analyzed the differences between the scanners in their ability to detect perfusion defects.
METHODS: We analyzed retrospectively the clinical and imaging data of 140 consecutive acute (<3 h) stroke patients who underwent multimodal CT evaluation and received intravenous rtPA. Alberta Stroke Program Early CT Score (ASPECTS) was assigned to PCT maps. Clinical and imaging parameters were compared between the two scanners.
RESULTS: There were more motion artifacts in the 16-row studies (p = 0.04), and the analysis software was able to completely correct significantly fewer of these (p < 0.001). Both ASPECTS levels were optimally covered in only 29% of the 16-row studies, whereas in the 64-row studies, both levels were invariably optimally visualized (p < 0.001). This significantly decreased the sensitivity of the 16-row scanner to detect perfusion defects in the upper ASPECTS level (p = 0.02). The 64-row scanner was able to detect more perfusion defects that were located entirely outside the ASPECTS regions (p = 0.03). There was no significant difference in the 3-month functional outcome.
CONCLUSIONS: The 16-row scanner suffered from limited anatomic coverage that decreased the sensitivity to detect perfusion defects in the cranial parts of the middle cerebral artery region. The 16-row studies had poorer technical quality that was in part attributable to higher sampling frequency and smaller slice thickness making the imaging more sensitive to small-scale movement of the patient.