Schindera Sebastian T, Nelson Rendon C, Mukundan Srinivasan, Paulson Erik K, Jaffe Tracy A, Miller Chad M, DeLong David M, Kawaji Keigo, Yoshizumi Terry T, Samei Ehsan
Department of Radiology, Duke University Medical Center, Box 3808, Erwin Rd, Durham, NC 27710, USA.
Radiology. 2008 Jan;246(1):125-32. doi: 10.1148/radiol.2461070307.
To prospectively evaluate, for the depiction of simulated hypervascular liver lesions in a phantom, the effect of a low tube voltage, high tube current computed tomographic (CT) technique on image noise, contrast-to-noise ratio (CNR), lesion conspicuity, and radiation dose.
A custom liver phantom containing 16 cylindric cavities (four cavities each of 3, 5, 8, and 15 mm in diameter) filled with various iodinated solutions to simulate hypervascular liver lesions was scanned with a 64-section multi-detector row CT scanner at 140, 120, 100, and 80 kVp, with corresponding tube current-time product settings at 225, 275, 420, and 675 mAs, respectively. The CNRs for six simulated lesions filled with different iodinated solutions were calculated. A figure of merit (FOM) for each lesion was computed as the ratio of CNR2 to effective dose (ED). Three radiologists independently graded the conspicuity of 16 simulated lesions. An anthropomorphic phantom was scanned to evaluate the ED. Statistical analysis included one-way analysis of variance.
Image noise increased by 45% with the 80-kVp protocol compared with the 140-kVp protocol (P < .001). However, the lowest ED and the highest CNR were achieved with the 80-kVp protocol. The FOM results indicated that at a constant ED, a reduction of tube voltage from 140 to 120, 100, and 80 kVp increased the CNR by factors of at least 1.6, 2.4, and 3.6, respectively (P < .001). At a constant CNR, corresponding reductions in ED were by a factor of 2.5, 5.5, and 12.7, respectively (P < .001). The highest lesion conspicuity was achieved with the 80-kVp protocol.
The CNR of simulated hypervascular liver lesions can be substantially increased and the radiation dose reduced by using an 80-kVp, high tube current CT technique.
前瞻性评估在体模中对模拟的富血供肝脏病变进行成像时，低管电压、高管电流计算机断层扫描（CT）技术对图像噪声、对比噪声比（CNR）、病变显示度及辐射剂量的影响。
使用含16个圆柱形腔（直径分别为3、5、8和15mm的腔各4个）的定制肝脏体模，这些腔填充有各种碘化溶液以模拟富血供肝脏病变，用64排多层螺旋CT扫描仪分别在140、120、100和80kVp进行扫描，相应的管电流 - 时间乘积设置分别为225、275、420和675mAs。计算填充不同碘化溶液的6个模拟病变的CNR。计算每个病变的优值（FOM），即CNR²与有效剂量（ED）之比。三名放射科医生独立对16个模拟病变中的显示度进行分级。扫描一个仿真人体模型以评估ED。统计分析包括单因素方差分析。
与140kVp扫描方案相比，80kVp扫描方案的图像噪声增加了４５％（P <.001）。然而，80kVp扫描方案实现了最低的ED和最高的CNR。FOM结果表明，在恒定ED下，管电压从140kVp降至120、100和80kVp时，CNR分别至少增加了1.6、2.4和3.6倍（P <.001）。在恒定CNR下，相应的ED降低分别为2.5、5.5和12.7倍（P <.001）。80kVp扫描方案实现了最高的病变显示度。
使用80kVp、高管电流CT技术可显著提高模拟富血供肝脏病变的CNR并降低辐射剂量。
