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

Cincinnati Children's Hospital Medical Center, OH 45229, USA.
American Journal of Roentgenology (Impact Factor: 2.73). 05/2011; 196(5):W592-7. DOI: 10.2214/AJR.10.5486
Source: PubMed


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.

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    • "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. "
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    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.
    Korean journal of radiology: official journal of the Korean Radiological Society 07/2013; 14(4):677-82. DOI:10.3348/kjr.2013.14.4.677 · 1.57 Impact Factor
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    ABSTRACT: In 122 children (ages, newborn to 17 years) without urinary tract disease, 244 kidneys were examined sonographically. Renal length and volume were measured and correlated with age, body weight, height, and total body surface area, permitting preparation of nomograms with predicted means and 95% prediction intervals. Also evaluated were renal parenchymal echogenicity, medullary pyramids, and central sinus echoes, and the appearance of each was correlated with age.
    American Journal of Roentgenology 10/1985; 145(3):611-6. DOI:10.2214/ajr.145.3.611 · 2.73 Impact Factor
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    ABSTRACT: The article presents the most frequent errors made in the ultrasound diagnosis of the urinary system. They usually result from improper technique of ultrasound examination or its erroneous interpretation. Such errors are frequent effects of insufficient experience of the ultrasonographer, inadequate class of the scanner, insufficient knowledge of its operation as well as of wrong preparation of patients, their constitution, severe condition and the lack of cooperation during the examination. The reasons for misinterpretations of ultrasound images of the urinary system may lie in a large polymorphism of the kidney (defects and developmental variants) and may result from improper access to the organ as well as from the presence of artefacts. Errors may also result from the lack of knowledge concerning clinical and laboratory data. Moreover, mistakes in ultrasound diagnosis of the urinary system are frequently related to the lack of knowledge of the management algorithms and diagnostic possibilities of other imaging modalities. The paper lists errors in ultrasound diagnosis of the urinary system divided into: errors resulting from improper technique of examination, artefacts caused by incorrect preparation of patients for the examination or their constitution and errors resulting from misinterpretation of ultrasound images of the kidneys (such as their number, size, fluid spaces, pathological lesions and others), ureters and urinary bladder. Each physician performing kidney or bladder ultrasound examination should possess the knowledge of the most frequent errors and their causes which might help to avoid them.
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