阈值法测量CT图像中肺血管体积

目的 探讨采用阈值法测量CT图像中肺血管体积的可行性.方法 制作7个不同体积的血管床模型,注入不同浓度的碘普罗胺,行CT扫描.分别采用-600、-500、-300 HU,-200 HU作为阈值下限进行分割,测量血管模型体积和体积相对误差.对20例患者先后进行2次胸部CT增强扫描,采用-300 HU作为阈值下限进行分割,由2名操作者测量肺血管体积.进行统计学分析.结果 除阈值下限为-300 HU时测量的肺血管体积与实际体积差异无统计学意义(P=0.375),其余阈值下限测得的肺血管体积与实际体积差异均有统计学意义(P均<0.05).不同浓度碘普罗胺时测量的肺血管模型体积与实际体积差异无统计学意义(P均>0.05).2次CT扫描测量的血管体积有很好的一致性(r=0.94,95%CI:0.85~0.98),且2名操作者间亦有很好的一致性(r=0.96,95%CI:0.91~0.99).结论 阈值法可准确、可靠地测量CT图像中肺血管体积.

Threshold-based method in measurement of pulmonary vessels volume in CT image

Objective To explore the feasibility of threshold-based method in measurement of pulmonary vessels volume in CT image. Methods Seven blood vessel bed phantoms of different volumes were made, and filled with different concentration of iopromide, then scanned by CT. CT data were segmented at different lower limit threshold of -600 HU, -500 HU, -300 HU and -200 HU. The blood volume of phantoms and relative error were measured. Twenty patients underwent twice chest enhanced CT scan. CT data were segmented at lower limit threshold of -300 HU, and the pulmonary vessel volume was measured by 2 operators. Statistical analysis was carried out. Results There were significant difference between the measuring pulmonary vessel volume and the true volume at different limit thresholds (all P<0.05), except for the threshold of -300 HU (P=0.375). There were no significant difference between the measuring pulmonary vessel volume and the true volume with different concentration of iopromide (all P>0.05). The consistency was good between measuring pulmonary vessel volume of 2 times CT scan (r=0.94, 95%CI:0.85-0.98), and the consistency was also good between 2 operators (r=0.96, 95%CI:0.91-0.99). Conclusion The threshold-based 3D quantitative CT volumetry enables accurate and reproducible measurement of pulmonary vessels volume. Threshold-based method can measure pulmonary vessels volume in CT image accurately and reliably.