高速CT灌注成像感兴趣区的选择对肺癌灌注参数的影响

Quantitative assessment of lung cancer tumor vascular parameters by using high speed perfusion CT： influence of tumor region of interest

目的探讨256层螺旋CT肺癌灌注成像中不同ROI选择方法对测量结果准确性的影响。方法对27例经临床确诊为肺癌的患者行肺CT灌注扫描。将所得图像传入工作站做后处理，ROI的选择采用60、120mm。和最大层面全肿瘤大小3种方式，分别获得中心区和边缘区的灌注值、血容量和强化峰值等灌注参数，并与其中19例手术患者微血管密度（MVD）进行相关分析，以配对t检验对所获得的各种灌注参数值进行比较。结果在60和120mm。的ROI，边缘区所测得灌注值（M：15．40、9．50ml·min-1·100ml-1）、血容量（M=35．60、25．40ml·100g。）及强化峰值（M：16．47、10．20HU）均高于中心区灌注值（M：14．80、8．52ml·min-1·100ml-1）、血容量（M=33．50、23．90ml·100g-1）及强化峰值（M=15．64、9．40HU），差异有统计学意义（t值分别为10．95、9．80、7．06、2．93、7．74和10．09，P值均〈0．05）；包括全肿瘤大小的ROI所测灌注值（M=12．51ml·min-1·100ml-1）、血容量（M=29．31ml·100g-1）及强化峰值（M=12．93HU）介于上述两者之间。包括全肿瘤大小的ROI所测灌注值、血容量及强化峰值与MVD[（19．43±8．78）条／0．74mm2]相关性最好（r值分别为0．732、0．590和0．544，P值均〈0．05）。结论R01的位置和大小均影响灌注参数值；以最大层面全肿瘤区域法划定ROI，可获得比随机勾画ROI准确性更高的数据。

Objective To prospectively determine whether position and size of tumor region of interest （ROI） influence estimates of lung cancer vascular parameters at 256-slice CT perfusion study. Methods After institutional review board approval and informed consent, 16 men and 11 women with lung cancer underwent 70-second CT perfusion study. Perfusion, blood volume, peak enhancement were determined for 60 or 120 mm2 circular ROIs placed at the tumor edge and center and around （outlining） visible tumor. ROI analysis was repeated twice by two observers in the same way to get the average values. The eone^ation between the measurements and microvascular density counts was determined in 19 patients with operation. Measurements were compared by using Pair-Samples t test, a difference with P ~ 0. 05 was significant. Results Peffusion, blood volume, peak enhancement measurements were substantially higher at the edge than at the center for both 60 and 120 mm2 ROI. For 60 and 120 mm2 ROI, median of the three measurements were （M=15.40,9.50 ml · min-1 .100 ml-l,M=35.60,25.40 ml 100 g-l,and M= 16. 47,10. 20 HU）, respectively, at the edge versus（M = 14. 80,8.52 ml·min-1 100 ml -1 ,M = 33.50, 23.90 ml · 100 g-1, and M = 15.64,9.40 HU） , respectively, at the center （t value was 10. 95 ,9.80, 7. 06,2. 93,7. 74 and 10. 09, respectively, all P 〈 0. 05 ）. Measurements varied substantially depending on the ROI size, values for the ROI for outlined tumor were intermediate between those at the tumor edge and center. Perfusion（M = 12.51 ml· min-1· 100 ml-1）, blood volume（M =29.31 ml · 100 g-1）, peak enhancement （M = 12. 93 HU） for the ROI outlining tumor were intermediate between those at the tumor edge and center. There was a good correlation between perfusion, blood volume, peak enhancement for the ROI outlining tumor and microvascular density[ （ 19. 43 ＋ 8.78 ） vessels/0. 74 mm2 ], respectively （ r value 0. 732, 0. 590 and 0. 544, all P 〈 0.05 ） . Conclusions Position and size of tumor ROI substantially influence ultimate perfusion values. ROI for outlined entire tumor is more reliable for perfusion measurements and more appropriate clinically than use of arbitrarily determined smaller ROI.