관류 자기공명 영상으로부터 Collateral Blood Volume 영상의 재구성

Abstract

Purpose : To reconstruct a collateral blood volume map from the total regional cerebral blood volume(rCBV) map using a-variate function that was used in fitting of the relaxivity()-time curve to separate the direct 1st pass rCBV.

Materials and Methods : MR images used in this study were obtained at 1.5T clinical MRI systems equipped with EPI capability(GE Horizon, Wisconsin USA; Siemens Vision, Erlangen, Germany), with the scan parameters TR/TE 1500/65 and 1200/42 msec respectively. The perfusion series were processed on a pixel-by-pixel basis by the home-made program under the commercial image analysis software IDL(Interactive Data Language, Research Systems Inc., CO, USA). The signal-time curve was converted into-time curve. The change in transverse relaxivity is known to be proportional to the concentration of contrast agent remaining in the tissue. The total rCBV maps was constructed by summation of the, before including the recirculation of Gd-DTPA. The fitted curve was summed for the frigst pass rCBV. Two summed values, the direct sum and the fitted sum, were subtracted to each other,in pixel-by-pixel. the time from a starting of dynamic change to the peak of was searched for time-to-peak(TTP) map.

Results : The total and the first pass rCBV maps were respectively constructed by summation of the directcurves and of the-variate fittedcurves during the first pass time. The subtraction of the first pass rCBV from the total rCBV was assigned to the collateral blood volume map. The TTP map presented the time from a starting of dynamic change to the maximum peak ofcurve.

Conclusion : Elimination of the direct 1st pass rCBV from the total rCBV during the 1st pass time resulted in the collateral blood volume map. The information about this secondary flow may be important for understanding of the hemodynamics of a certain disease such as moyamoya. The perfusion time map(TTP map). could be used as another parametric information about the abnormal local hemodynamics.