Reliability of Renal Length Measurements Made With Ultrasound Compared With Measurements From Helical CT Multiplanar Reformat Images

ArticleinAmerican Journal of Roentgenology 196(5):W592-7 · May 2011with18 Reads
DOI: 10.2214/AJR.10.5486 · Source: PubMed
Abstract
The purpose of this article is to determine the reliability of sonographic renal length measurements compared with measurements obtained from helical CT multiplanar reformat images and compared with standard renal growth curves. A retrospective review was performed of 76 subjects who underwent both renal ultrasound and abdominal CT within 2 weeks of one another. Renal lengths were measured using oblique coronal reformat images of helically acquired CT data by two observers on two occasions. Intraobserver and interobserver error for these measurements were calculated. Ultrasound renal length measurements were compared with CT measurements. Measurement variation was compared with standard renal growth curves. The mean (± SD) of the absolute value of interobserver error of CT measurements was 0.9 ± 0.8 mm. Compared with CT, individual ultrasound measurements underestimated renal length by 1.5 ± 5.6 mm on average, with a 95% CI of -12.5 to 9.5 mm. When the maximum of three ultrasound renal length measurements was used, the SD was 4.7 mm, with a 95% CI of -8.2 to 10.1 mm of the reported renal length. This corresponds to greater or less than 3.3 years of normal renal growth. Lack of renal growth can be asserted only when renal length falls below the growth curve, taking into account the corresponding measurement error limits, which we found to be greater or less than 9.3 mm. If the follow-up measurement falls within these limits, one should not infer lack of appropriate renal growth, even if the renal length measurement decreases or remains unchanged for up to 3 years.
    • "Other modalities have also been studied in renal length evaluation. Ultrasound has been found to underestimate renal length when compared with CT, MRI, and gross transplant measurements [6, 10, 11, 15]. SPECT with 99m Tc-dimercaptosuccinic acid has also been evaluated for renal length and showed mild overestimation of the true length [13]. "
    [Show abstract] [Hide abstract] ABSTRACT: Objective: The objective of this study was to determine the accuracy of renal measurement on CT in multiple imaging planes. Materials and methods: In this study, three board-certified radiologists retrospectively measured 110 kidneys on CT in 55 consecutive patients. Five measurement methods were used: axial, coronal single image, coronal multiimage, sagittal single image, and sagittal multiimage. The coronal database was sent to a postprocessing workstation, and each radiologist performed a maximum renal measurement using a best off-axis plane that was our reference standard. An ANOVA test with repeated measures and posthoc Bonferroni corrected t tests were performed. Results: The mean differences (± standard error) compared with the reference standard method were as follows: axial, 7.7 ± 0.7 mm; coronal single image, 13.1 ± 1.4 mm; coronal multiimage, 6.4 ± 0.8 mm; sagittal single image, 6.4 ± 0.6 mm; and sagittal multiimage, 2.8 ± 0.3 mm. The reference standard measurement was larger (p < 0.001), whereas the coronal single-image measurement (p ≤ 0.006) was smaller than all other methods. The sagittal multiimage (p ≤ 0.005) was statistically significantly different from all other methods. There were no statistically significant differences among the axial, coronal multiimage, and sagittal single-image methods (p ≥ 0.088). Conclusion: The single-image coronal method is the least accurate, with an error of approximately 13 mm. The axial, multiimage coronal, and single-image sagittal methods underestimate renal size by approximately 6-8 mm. Multiimage sagittal is the most accurate method for measuring kidneys with an error of approximately 3 mm.
    Article · Sep 2015
    • "However, the kidney contour is not exact ellipse and this method have large intra-and interobserver variations [4]. More accurate measurement can be achieved by using a voxel-count method on computed tomography (CT) [3] or magnetic resonance (MR) images [4]. However, the harmful ionizing radiation for CT, and the increasing scanning time for MR prevent these methods from repeated clinical use. "
    [Show abstract] [Hide abstract] ABSTRACT: An accurate, repeatable and noninvasive measurement of kidney volume is an important but difficult task for nephrologists. This paper proposes a new kidney volumetry method by reconstructing the kidney surface from three-dimensional ultrasonography (3DUS) using statistical shape model (SSM). The measurement starts with picking sparse points on the kidney contour from 3DUS images. Then an accurate 3D kidney surface mesh can be reconstructed from the input points using the SSM in a fine-tune way. The kidney volume is finally calculated from the surface using divergence theorem of Gauss. The accuracy and repeatability of the proposed method have been validated on 36 patients. The results demonstrate that the proposed method is a promising solution for clinical evaluation of the kidney volume.
    Full-text · Conference Paper · Aug 2015 · Korean journal of radiology: official journal of the Korean Radiological Society
    • "First, it was a retrospective study of renal size even though renal length and width measurements were routinely performed by two pediatric radiologists. The second limitation is that we examined renal size only by US, which has indicated a relatively high intra- and inter-observer error with previous studies (19, 20). The difference in US techniques, patient positioning, and cursor placement can affect the reproducibility of measurements on renal length. "
    [Show abstract] [Hide abstract] ABSTRACT: To evaluate the relationship between anthropometric measurements and renal length and volume measured with ultrasound in Korean children who have morphologically normal kidneys, and to create simple equations to estimate the renal sizes using the anthropometric measurements. We examined 794 Korean children under 18 years of age including a total of 394 boys and 400 girls without renal problems. The maximum renal length (L) (cm), orthogonal anterior-posterior diameter (D) (cm) and width (W) (cm) of each kidney were measured on ultrasound. Kidney volume was calculated as 0.523 × L × D × W (cm(3)). Anthropometric indices including height (cm), weight (kg) and body mass index (m(2)/kg) were collected through a medical record review. We used linear regression analysis to create simple equations to estimate the renal length and the volume with those anthropometric indices that were mostly correlated with the US-measured renal sizes. Renal length showed the strongest significant correlation with patient height (R(2), 0.874 and 0.875 for the right and left kidneys, respectively, p < 0.001). Renal volume showed the strongest significant correlation with patient weight (R(2), 0.842 and 0.854 for the right and left kidneys, respectively, p < 0.001). The following equations were developed to describe these relationships with an estimated 95% range of renal length and volume (R(2), 0.826-0.884, p < 0.001): renal length = 2.383 + 0.045 × Height (± 1.135) and = 2.374 + 0.047 × Height (± 1.173) for the right and left kidneys, respectively; and renal volume = 7.941 + 1.246 × Weight (± 15.920) and = 7.303 + 1.532 × Weight (± 18.704) for the right and left kidneys, respectively. Scatter plots between height and renal length and between weight and renal volume have been established from Korean children and simple equations between them have been developed for use in clinical practice.
    Full-text · Article · Jul 2013
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