Ciaschini Michael W, Remer Erick M, Baker Mark E, Lieber Michael, Herts Brian R
Section of Abdominal Imaging, Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, Room A21, Cleveland, OH 44195, USA.
Radiology. 2009 Apr;251(1):105-11. doi: 10.1148/radiol.2511081084. Epub 2009 Feb 27.
To retrospectively determine the effect of 50% and 75% dose reduction on sensitivity and specificity of computed tomography (CT) for the detection of urinary calculi.
This HIPAA compliant study was institutional review board approved; informed consent was waived. Raw CT data from 47 consecutive patients (24 male patients, 23 female patients; mean age, 46.0 years) who underwent unenhanced CT for flank pain were collected. Original CT examinations were performed by utilizing an automated dose modulation algorithm. Reconstructions of raw CT data were performed at 100%, 50%, and 25% of the original tube current by using simulation software; tube currents averaged 177, 88, and 44 mA, respectively. All reconstructed examinations were randomized and evaluated by two radiologists blinded to the presence, number, location, and size of calculi. The opinion of an unblinded radiologist who separately reviewed the original examination and report and the electronic medical record served as the reference standard. One hundred eight calculi (85 renal, 21 ureteral, and two in the bladder) were present in 32 of 47 patients. Calculus diameter ranged from 0.14 to 1.32 cm (mean, 0.34 cm). The decrease in sensitivity was assessed between doses and was independently evaluated for all calculi and separately for calculi greater than 3 mm in diameter by using the McNemar test, adjusted for clustered data.
For all calculi, the blinded readers demonstrated combined sensitivities of 91.7%, 83.3%, and 67.1% for the 100%, 50%, and 25% tube current reconstructions, respectively. For stones greater than 3 mm, combined sensitivities were 97.7%, 93.0%, and 91.9%, respectively, for the 100%, 50%, and 25% reconstructions. There was no significant difference between the 100% examinations and the 50% and 25% reconstructions for detection of stones greater than 3 mm (P = .106 and .099, respectively).
There were no significant differences between the 100% examinations and the 50% and 25% examinations for the detection of calculi greater than 3 mm.
回顾性确定将计算机断层扫描（CT）剂量降低50%和75%对检测尿路结石的敏感度和特异度的影响。
本符合健康保险流通与责任法案（HIPAA）的研究经机构审查委员会批准；豁免了知情同意。收集了47例因胁腹疼痛接受非增强CT检查的连续患者（24例男性患者，23例女性患者；平均年龄46.0岁）的原始CT数据。原始CT检查采用自动剂量调制算法进行。利用模拟软件将原始CT数据分别以原始管电流的100%、50%和25%进行重建；管电流平均分别为177、88和44毫安。所有重建检查均进行随机分组，并由两名对结石的存在、数量、位置和大小不知情的放射科医生进行评估。一名未参与盲法评估的放射科医生单独审查原始检查、报告及电子病历，以此作为参考标准。47例患者中有32例存在108枚结石（85枚位于肾脏，21枚位于输尿管，2枚位于膀胱）。结石直径范围为0.14至1.32厘米（平均0.34厘米）。采用McNemar检验评估不同剂量之间敏感度的降低情况，并针对聚集数据进行调整，分别对所有结石以及直径大于3毫米的结石独立进行评估。
对于所有结石，参与盲法评估的阅片者对管电流为100%、50%和25%重建图像的联合敏感度分别为91.7%、83.3%和67.1%。对于直径大于3毫米的结石，管电流为100%、50%和25%重建图像的联合敏感度分别为97.7%、93.0%和91.9%。在检测直径大于3毫米的结石方面，100%剂量的检查与50%和25%剂量重建图像之间无显著差异（P值分别为0.106和0.099）。
在检测直径大于3毫米的结石方面，100%剂量的检查与50%和25%剂量的检查之间无显著差异。
