對標準體型病人行低管電壓CT肺動脈成像的可行性研究

趙磊楊曉光包麗麗劉挨師

對標準體型病人行低管電壓CT肺動脈成像的可行性研究

趙磊1楊曉光1包麗麗2劉挨師1

目的通過對比低管電壓CT肺動脈成像（CTPA）與常規CTPA的影像質量與輻射劑量，從而評價低管電壓CTPA應用于標準體型病人的臨床價值。方法前瞻性選取我院2013年2月—2014年8月標準體型（體質量指數≤25 kg/m2，體質量≤80 kg）病人60例，并隨機分為2組。A、B兩組管電壓分別設置為80 kV和120 kV。管電流設置基于循環時間測試峰值。評價并對比A、B兩組影像質量與輻射劑量，選取肺動脈干影像質量參數與輻射劑量進行Pearson相關性分析。結果A組總體肺動脈CT值與噪聲值高于B組，差異具有統計學意義（P= 0.000）。A組總體肺動脈SNR和CNR與B組相比差異無統計學意義（分別P=0.187，P=0.309）。A組有效劑量顯著低于B組［（1.69±0.43）mSv∶（5.63±1.84）mSv，P=0.000］。有效劑量與CT值和噪聲值呈負相關。結論低管電壓CTPA應用于標準體型病人可以有效減低輻射劑量，同時保證影像質量，具有臨床應用價值。

體層攝影術，X線計算機；血管成像；肺栓塞

DOI：10.19300/j.2016.L3343

【Abstract】ObjebtiveThe purpose of this study was to compare image quality and radiation dose between low voltage CT pulmonary angiography（CTPA）and conventional CTPA protocols in patients of standard body type.Methods60 consecutive patients with low body mass index（≤25 kg/m2）and low body mass（≤80 kg）suspected having pulmonary embolism（PE）were prospectively enrolled from February 2013 to August 2014.The patients were divided into two groups. Tube voltage was set at 80 kV for group A and 120 kV for group B.Tube current settings were determined by testing bolus peak attenuation.Radiation dose and image quality were compared between the two groups.The relationship between image quality parameter and radiation dose measured at pulmonary artery trunk were analyzed with Pearson correlation.Results The total pulmonary arteries showed significantly higher attenuation and noise in group A than in group B（P=0.000）.The total signal-to-noise ratio and total contrast-to-noise ratio did not significantly differ between groups A and B（P=0.187，P= 0.309，respectively）.The mean effective dose showed significantly lower in group A than in group B（1.69±0.43 mSv vs 5.63± 1.84 mSv，P=0.000）.The attenuation or noise and effective dose was negatively correlated.ConclusionUsing 80 kV-CTPA can achieve stable image quality with reduced effective radiation dose compared with 120 kV-CTPA in patients with low body mass index（≤25 kg/m2）and low body mass（≤80 kg）.

【Key words】Tomography，X-ray computed；Angiography；Pulmonary embolism

Int J Med Radiol，2016，39（2）：107-110；115

CT肺血管成像（CT pulmonary angiography，CTPA）是一種對可疑肺栓塞篩查或肺栓塞溶栓后評價的重要診斷工具，已常規應用于臨床實踐［1］。由于其掃描范圍覆蓋整個胸部，因而輻射劑量較高［2］。近年來，隨著迭代重建算法的投入使用，80～100 kV逐漸開始替代120～140 kV［3-6］。低管電壓可以提高靶血管的衰減值，與120 kV相比，80 kV下的X線更易產生光電效應，從而一定程度上提高了影像質量［7］。多項100 kV與80 kV的研究均得出了上述結論［3-6，8］。本研究嘗試通過降低管電壓來降低輻射劑量，并與常規CTPA方案進行影像質量與輻射劑量的比較，從而明確其臨床應用的可行性。……