Lin E, Connolly L P, Zurakowski D, DiCanzio J, Drubach L, Mitchell K, Tetrault T, Laffin S P, Treves S T
Department of Radiology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Nucl Med. 2000 Oct;41(10):1632-5.
Renal length measurements are used in evaluating several abnormalities of the pediatric genitourinary tract. This study assesses reproducibility of renal length measurements obtained with 99mTc-dimercaptosuccinic acid (DMSA) SPECT.
The lengths of 98 kidneys of 51 children (age range, 1-16 y; mean age, 5.4 y) who underwent 99mTc-DMSA SPECT were measured independently by 2 observers. Renal length was calculated by converting pixels between points at the superior and inferior renal margins on a summated coronal image to centimeters. Lengths were measured for kidneys as they appeared in situ and after realignment along their long axes. SPECT reconstruction, choice of display parameters, positioning of points used for measuring, and alignment were performed independently by each observer. Interobserver variability, interobserver correlation, and mean differences between observers' measurements (expressed as measurement of observer 2 - measurement of observer 1) were calculated.
Correlation between the observers' measurements was highly significant for both nonaligned and aligned studies (r = 0.95 and 0.97, respectively; both, P < 0.0001). Interobserver variability expressed as 1 SD was 3.6 mm for nonaligned studies and 2.8 mm for aligned studies. The mean difference between the 2 observers' measurements for nonaligned studies was 2.0 +/- 4.8 mm (P < 0.0001) with a range of -11 to 14 mm. For aligned studies the mean difference between the 2 observers' measurements was -0.1 +/- 4.0 mm (P = 0.88) with a range of -20 to 10 mm. Differences between observers were not dependent on absolute renal length (P = 0.68 for nonaligned studies; P = 0.40 for aligned studies).
The variability in renal length measurements determined by 99mTc-DMSA SPECT is similar to that reported previously using sonography. Because the interobserver differences in renal length are similar to annual renal growth rates during childhood, caution should be applied when incorporating renal length measurements determined by 99mTc-DMSA SPECT into management algorithms. Additional studies are required to further establish interobserver variability, to assess intraobserver variability, and to evaluate means of improving standardization.
肾长度测量用于评估小儿泌尿生殖道的多种异常情况。本研究评估了用99m锝-二巯基丁二酸（DMSA）单光子发射计算机断层扫描（SPECT）获得的肾长度测量的可重复性。
对51名儿童（年龄范围1至16岁；平均年龄5.4岁）的98个肾脏进行了99mTc-DMSA SPECT检查，由2名观察者独立测量肾脏长度。通过将冠状位叠加图像上肾上下边缘点之间的像素转换为厘米来计算肾长度。分别测量肾脏在原位时以及沿其长轴重新对齐后的长度。每位观察者独立进行SPECT重建、显示参数选择、测量点定位和对齐操作。计算观察者间的变异性、观察者间的相关性以及观察者测量值之间的平均差异（表示为观察者2的测量值 - 观察者1的测量值）。
对于未对齐和对齐研究，观察者测量值之间的相关性均高度显著（分别为r = 0.95和0.97；均P < 0.0001）。以1个标准差表示的观察者间变异性，未对齐研究为3.6毫米，对齐研究为2.8毫米。未对齐研究中2名观察者测量值的平均差异为2.0 +/- 4.8毫米（P < 0.0001），范围为 - 11至14毫米。对于对齐研究，2名观察者测量值的平均差异为 - 0.1 +/- 4.0毫米（P = 0.88），范围为 - 20至10毫米。观察者之间的差异不取决于绝对肾长度（未对齐研究P = 0.68；对齐研究P = 0.40）。
99mTc-DMSA SPECT测定的肾长度测量变异性与先前报道的超声检查相似。由于观察者间肾长度差异与儿童期每年的肾脏生长速率相似，在将99mTc-DMSA SPECT测定的肾长度测量纳入管理算法时应谨慎。需要进一步开展研究以进一步确定观察者间变异性、评估观察者内变异性并评估提高标准化的方法。
