衰减校正和散射校正对单光子发射计算机断层成像图像质量的影响

Effection of CT attenuation correction and scatter correction on SPECT image quality

目的探讨CT衰减校正(CTAC)和双能窗散射校正(SC)对SPECT图像质量的影响。方法分别对Jaszczak模型、IEC体模及16例患者进行SPECT断层显像,并分别进行以下4种校正状态下的图像重建:无衰减校正(NO-AC)无散射校正(NOSC)、SC NOAC、CTAC SC、CTAC NOSC。比较不同校正状态下Jaszczak模型冷区和本底区放射性计数、冷区对比度及均匀区积分均匀性百分比、IEC体模各热区及患者病灶靶/本底比值,并进行统计学分析。结果与Jaszczak模型的NOAC NOSC图像比较:1CTAC NOSC图像可显著提高冷区和本底区的放射性计数(P<0.05);降低均匀区的积分均匀性百分比(P<0.05);冷区对比度的差异无统计学意义(P>0.05)。2SC NOAC显著降低了冷区和本底区的放射性计数(P均<0.05);提高了均匀区的积分均匀性百分比(P<0.05);显著提高了冷区对比度(P均<0.05)。3CTAC SC提高了冷区和本底区的放射性计数及冷区对比度(P均<0.05);降低了均匀区的积分均匀性百分比(P<0.05)。与IEC体模及患者的NOAC NOSC图像比较,CTAC NOSC图像各热区及病灶的靶/本底比值差异均无统计学意义(P均>0.05),SC NOAC图像各热区(除直径10mm)及病灶的靶/本底比值均较大(P均<0.05),CTAC SC图像各热区及病灶的靶/本底比值均较大(P均<0.05)。结论 CTAC可提高图像放射性计数及均匀性,SC可提高图像对比度,将两者结合可获得较高的图像质量。

Objective To evaluate the effect of CT attenuation correction （CTAC） and scatter correction （SC） on SPECT image quality.Methods Jaszczak phantom, IEC body phantom and sixteen patients were scanned with SPECT. Four correction methods were used to reconstruct the images：no attenuation correction （NOAC） no scatter correction （NOSC）, scatter correction （SC） NOAC, CT attenuation correction （CTAC） SC, CTAC NOSC. Cold area and background area radioactive count, cold area contrast and integral uniformity percentage of images reconstructed by different correction methods were compared in Jaszczak phantom. In images reconstructed by different correction methods, target/background ratio of hot area in IEC body phantom and patients＇ lesion was compared. Statistical analysis was performed.Results Compared with NOAC NOSC of Jaszczak phantom images：①In CTAC NOSC images, radioactive count in cold area and background area increased markedly; integral uniformity percentage in uniformity area decreased （P〈0.05）; the difference of cold area contrast had no statistical significance in CTAC NOSE images （all P〉0.05）. ②In SC NOAC images, radioactive count in cold area and background area decreased markedly （all P〈0.05）; integral uniformity percentage in uniformity area and cold area contreast increased （P〈0.05）. ③In CTAC SC images, radioactive count in cold area and background area increased （all P〈0.05）. Integral uniformity percentage in uniformity area decreased （P〈0.05）. Compared with NOAC NOSC of IEC body phantom and patient images, the difference of target/background ratio had no statistical significance in CTAC NOSC images （all P〉0.05）; target/background ratio of different hot area （except diameter 10 mm） and lesion was bigger in SC NOAC images （all P〈0.05）; target/background ratio of different hot area and lesion was bigger in CTAC SC images （all P〈0.05）.Conclusion CTAC can improve radioactive count and image uniformity. SC can improve image contrast. It may obtain high quality image combining the two correction methods.