Jaakkola P, Hippeläinen M, Farin P, Rytkönen H, Kainulainen S, Partanen K
Department of Surgery, Kuopio University Hospital, Finland.
Eur J Vasc Endovasc Surg. 1996 Aug;12(2):230-7. doi: 10.1016/s1078-5884(96)80112-2.
To examine the interobserver variability in measuring the abdominal aorta by ultrasound (US) and computed tomography (CT).
A prospective clinical study in a university hospital.
Thirty-three patients whose abdominal aortas were scanned both with CT and US as a part of aneurysm investigation or for a variety of other reasons.
Three radiologists measured abdominal aortic diameters by US and CT. The interobserver differences (IOD) in US and CT and intraobserver differences for CT-US-pairs were analysed by various statistical methods. A new concept of "clinically acceptable difference" (CAD) was adopted denoting differences of less than 5mm.
The IOD in US was 2mm or less in 65% of the anteroposterior and 61% of the transverse measurements and 5mm or more in 11% of the anteroposterior and 14% in the transverse measurements in 102 observer pairs for all aortas. The IODs were significantly larger in measuring the aneurysmal aortas compared with normal aortas (p < 0.001). The CAD-value for the aneurysmal aortas was 84% in the anteroposterior and 82% in the transverse directions. In CT the IODs were 2mm or less in 62% of the anteroposterior and 66% of the transverse measurements and 5mm or more in 12% of both anteroposterior and transverse measurements in 94 observer pairs for all aortas. The CAD-value in the aneurysmal aortas was 91% in the anteroposterior and 85% in the transverse directions. There was no significant difference between the US and CT CAD-levels. The absolute CT-US difference of an individual observer was 2mm or less in 54%, 5mm or more in 17% and 10mm or more in 2% of the anteroposterior measurements in the 95 CT-US pairs. In the transverse direction the corresponding figures were: 2mm or less in 63%, 5mm or more 13% and 10mm or more in 2% of the pairs. The diameters obtained by US were smaller in 84% of the cases compared with those of CT in measuring the maximum aortic diameter in anteroposterior direction, whereas the same figure for the transverse measurements was 59%.
Both US and CT measurements are subject to significant interobserver variability that must be taken into account in the clinical follow-up of small abdominal aortic aneurysms and in screening studies. Neither of these methods can be considered as a 'gold standard'.
通过超声（US）和计算机断层扫描（CT）检查测量腹主动脉时观察者间的变异性。
在大学医院进行的一项前瞻性临床研究。
33例患者，其腹主动脉作为动脉瘤检查的一部分或因各种其他原因接受了CT和US扫描。
三名放射科医生通过US和CT测量腹主动脉直径。采用各种统计方法分析US和CT中的观察者间差异（IOD）以及CT-US配对的观察者内差异。采用了“临床可接受差异”（CAD）这一新概念，指差异小于5mm。
在所有主动脉的102对观察者中，US的IOD在前后径测量的65%和横径测量的61%中为2mm或更小，在前后径测量的11%和横径测量的14%中为5mm或更大。与正常主动脉相比，测量动脉瘤性主动脉时的IOD显著更大（p < 0.001）。动脉瘤性主动脉在前后方向的CAD值为84%，在横方向为82%。在CT中，所有主动脉的94对观察者中，IOD在前后径测量的62%和横径测量的66%中为2mm或更小，在前后径和横径测量的12%中为5mm或更大。动脉瘤性主动脉在前后方向的CAD值为91%，在横方向为85%。US和CT的CAD水平之间无显著差异。在95对CT-US配对中，个体观察者的绝对CT-US差异在前后径测量的54%中为2mm或更小，在17%中为5mm或更大，在2%中为10mm或更大。在横方向上，相应的数字为：63%的配对中为2mm或更小，13%中为5mm或更大，2%中为10mm或更大。在测量主动脉最大前后径时，84%的病例中US测得的直径小于CT测得的直径，而横径测量的这一数字为59%。
US和CT测量均存在显著的观察者间变异性，在小腹主动脉瘤的临床随访和筛查研究中必须予以考虑。这两种方法都不能被视为“金标准”。
