脊柱同源动态能谱CT与MSCT辐射剂量和图像质量的对比

目的探讨同源动态能谱CT和MSCT在脊柱扫描中的差异。方法将脊柱疾病患者50例随机分为A、B组两组,每组25例。A组采用同源双电压(80、140kVp)动态扫描,FBP重建单能量图像,记录图像噪声-能级曲线、椎体CNR随能量变化曲线,得出最低图像噪声值及最高CNR值的最佳能级,测量图像噪声及椎体CNR。B组常规MSCT扫描,FBP图像重建。比较两组辐射剂量、图像噪声和椎体CNR。结果 A组最佳能级为70keV,图像噪声为(16.12±1.48)HU,较B组(53.95±4.97)HU明显降低(t=3.25,P<0.05);CNR为5.89±0.46,是B组(1.67±0.15)的3.5倍(t=5.43,P<0.05);容积CT剂量指数为(7.64±0.71)mGy,较B组的(16.34±1.24)mGy降低了53%(t=15.62,P<0.05)。结论同源动态能谱CT脊柱成像较常规MSCT可明显降低辐射剂量,降低图像噪声,提高椎体CNR,改善图像质量。

Comparison of radiation dose and image quality between single source dual-energy CT and conventional multi-slice spiral CT of the spine

Objective To explore the differentiations of single source dual-energy (SSDE) CT and MSCT in spine imaging. Methods Fifty patients with spine diseases were randomly divided into A, B groups (each n=25). Group A underwent SSDE (80 and 140 kVp) CT scans, and monoenergetic images were reconstructed with FBP. The optimal energy level (keV) with lowest image noise and highest contrast to noise ratio (CNR) was determined by recording image noise-energy and vertebral CNR-energy curves, then the image noise and vertebral CNR were measured. Patients in group B underwent conventional MSCT with FBP reconstruction. Radiation dosage, image noise and spine CNR were statistically compared between the two groups. Results In group A, the optimal energy level was at 70 keV, which achieved the highest CNR and lowest noise. Image noise was (16.12±1.48)HU for 70 keV monoenergetic images and (53.95±4.97)HU for conventional CT (t=3.25, P<0.05). CNR of the vertebral for 70 keV monoenergetic images was 5.89±0.46, which was 3.5 times as many as CNR (1.67±0.15) for conventional MSCT (t=5.43, P<0.05). The CT dose index volume of the dual-energy CT was (7.64±0.71)mGy, which was 53% lower than that of the conventional MSCT ([16.34±1.24]mGy, t=15.62, P<0.05). Conclusion Compared with conventional spine MSCT, SSDE CT can reduce radiation dosage, decrease image noise, increase vertebral CNR and improve image quality.