Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
Invest Radiol. 2010 Apr;45(4):202-10. doi: 10.1097/RLI.ob013e3181dzfeec.
To assess radiation dose reduction for abdominal computed tomography (CT) examinations with adaptive statistical iterative reconstruction (ASIR) technique.
With institutional review board approval, retrospective review of weight adapted abdominal CT exams were performed in 156 consecutive patients with ASIR and in 66 patients with filtered back projection (FBP) on a 64-slice MDCT. Patients were categorized into 3 groups of <60 kg (n = 42), 61 to 90 kg (n = 100), and >or=91 kg (n = 80) for weight-based adjustment of automatic exposure control technique. Remaining scan parameters were held constant at 1.375:1 pitch, 120 kVp, 55 mm table feed per rotation, 5 mm section thickness. Two radiologists reviewed all CT examinations for image noise and diagnostic acceptability. CT dose index volume, and dose length product were recorded. Image noise and transverse abdominal diameter were measured in all patients. Data were analyzed using analysis of variance.
ASIR allowed for an overall average decrease of 25.1% in CT dose index volume compared with the FBP technique (ASIR, 11.9 +/- 3.6 mGy; FBP, 15.9 +/- 4.3 mGy) (P < 0.0001). In each of the 3 weight categories, CT examinations reconstructed with ASIR technique were associated with significantly lower radiation dose compared with FBP technique (P < 0.0001). There was also significantly less objective image noise with ASIR (6.9 +/- 2.2) than with FBP (9.5 +/- 2.0) (P < 0.0001). For the subjective analysis, all ASIR and FBP reconstructed abdominal CTs had optimal or less noise. However, 9% of FBP and 3.8% of ASIR reconstructed CT examinations were diagnostically unacceptable because of the presence of artifacts. Use of ASIR reconstruction kernel results in a blotchy pixilated appearance in 39% of CT sans which however, was mild and did not affect the diagnostic acceptability of images. The critical reproduction of visually sharp anatomic structures was preserved in all but one ASIR 40% reconstructed CT examination.
ASIR technique allows radiation dose reduction for abdominal CT examinations whereas improving image noise compared with the FBP technique.
评估自适应统计迭代重建（ASIR）技术在腹部 CT 检查中的辐射剂量降低效果。
经机构审查委员会批准，回顾性分析了 156 例连续接受 ASIR 扫描和 66 例接受滤波反投影（FBP）扫描的患者的体重适应腹部 CT 检查。根据体重调整自动曝光控制技术，将患者分为三组：<60kg（n=42）、61-90kg（n=100）和≥91kg（n=80）。其余扫描参数保持不变，即 1.375:1 螺距、120kVp、55mm 表进/转、5mm 层厚。两名放射科医生对所有 CT 检查的图像噪声和诊断可接受性进行了评估。记录 CT 剂量指数体积和剂量长度乘积。所有患者均测量图像噪声和横截面积。采用方差分析进行数据分析。
与 FBP 技术相比，ASIR 可使 CT 剂量指数体积平均降低 25.1%（ASIR，11.9±3.6mGy；FBP，15.9±4.3mGy）（P<0.0001）。在每个体重类别中，使用 ASIR 技术进行的 CT 检查与 FBP 技术相比，辐射剂量均显著降低（P<0.0001）。ASIR 技术的客观图像噪声也显著低于 FBP 技术（6.9±2.2）比（9.5±2.0）（P<0.0001）。在主观分析中，所有 ASIR 和 FBP 重建的腹部 CT 扫描均具有最佳或较低的噪声。然而，9%的 FBP 和 3.8%的 ASIR 重建 CT 检查因伪影而被认为诊断不可接受。使用 ASIR 重建核会导致 39%的 CT 扫描出现斑驳的像素化外观，但这种情况较轻，不会影响图像的诊断可接受性。除了一次 ASIR 重建 40%的 CT 扫描外，所有 ASIR 重建 CT 扫描均能清晰再现具有诊断意义的解剖结构。
与 FBP 技术相比，ASIR 技术可降低腹部 CT 检查的辐射剂量，同时改善图像噪声。
