DOI:10.2214/AJR.07.2431
AJR 2007; 189:873-874
© American Roentgen Ray Society
Graphic Representation of Skeletal Maturity Determinations
M. Ines Boechat1 and
David Choen Lee2
1 Department of Radiological Sciences, David Geffen School of Medicine at the
University of California, Los Angeles, 650 S Charles E. Young Dr., CHS B2-252,
Los Angeles, CA 90095-1721.
2 Department of Biomedical Engineering, University of Southern California, Los
Angeles, CA.
Received April 16, 2007;
revised May 19, 2007;
Address correspondence to M. I. Boechat
(iboechat{at}mednet.ucla.edu).
Abstract
OBJECTIVE. Skeletal maturation determinations are usually reported
as numeric data indicating accordance with chronologic age. However,
significant changes in skeletal maturation can occur without falling outside
two SDs. The purpose of our study was to design simple computer-generated
sex-based charts to enhance the evaluation of skeletal maturation, especially
when frequent assessments are made.
CONCLUSION. The graphic representation of successive reports clearly
depicts whether values retain their position in relation to the mean. In
addition, the report includes computation of the exact SD score.
Keywords: bone age • graphic representation • skeletal maturation
Introduction
Bone age assessment is frequently performed in children and adolescents for
the evaluation of growth and the diagnosis and management of a multitude of
endocrine disorders and pediatric syndromes. A single interpretation of
skeletal age informs the clinician of the relative maturity of a patient's
skeleton at a particular time and, integrated with other clinical findings,
separates normal skeletal maturation from relatively advanced or delayed
skeletal maturation. Successive skeletal age interpretations indicate the
direction of the child's development and show the progress under treatment. In
healthy subjects, bone age should fall roughly within two SDs of reference
norms, which are most commonly based on the Greulich and Pyle atlas
[1].
In contrast to other key anthropometric measurements, which are usually
documented on growth charts, bone age is reported in simple numeric form using
SD scores without any graphic representation. However, this reporting format
may limit our ability to discern the direction of a child's development and to
show the progress of abnormal skeletal maturation. For example, a 13-year-old
boy with short stature underwent three bone age determinations during the
previous 28 months, which were all reported as "...within two SDs for
his chronological age," despite a progressive decline in skeletal
maturity as a consequence of the development of hypothyroidism resulting from
a deficient and ectopic thyroid gland (Fig.
1). This clinical case encouraged us to design a simple
computer-generated chart to facilitate the evaluation of a child's skeletal
maturity.
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Fig. 1 —Skeletal maturity chart for boys comparing bone age and
chronologic age, including computation of three SD scores
(asterisks), shows progressively delayed skeletal maturation. Black
line = mean value, green lines = one SD, red lines = 2 SD.
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Materials and Methods
A bone age graphical user interface was designed and programmed as a
stand-alone application using MATLAB R2006a (The MathWorks). Because the
normal rate of skeletal maturity differs between males and females, charts
were developed based on sex (Figs.
1 and
2). The program outputs the
data to a graphic in which the x-axis is chronologic age and the
y-axis is bone age. In addition, the user can enter multiple data
points so that a child's progression over time can be mapped out and
visualized (Fig. 1).
Means and SDs for bone age were obtained from the norms generated by Harold
C. Stuart of the Department of Maternal and Child Health of the Harvard School
of Public Health in Boston, Massachusetts, as indicated in tables 5 and 6 of
the Greulich and Pyle Radiographic Atlas of Skeletal Development of the
Hand and Wrist [1]. The
underlying equation for calculating the SD of a child's bone age from the
expected bone age is
In this formula, BA is the subject's bone age in months, CA
is the subject's chronologic age in months, and SDBA is the SD of
BA as reported by Stuart. The program will accept bone ages and
chronologic ages between integers and calculate the weighted SD
accordingly.
Discussion
The evaluation of a child's skeletal maturity is generally reported in the
context of numeric data indicating the difference in SD scores between the
patient's bone age and chronologic age. When chronologic and skeletal ages
concur, the radiologist frequently reports the bone age to be in accordance
with or within one or two SDs of the chronologic age. However, significant
changes in skeletal maturation can occur without falling outside two SDs.
The simple computer-generated chart described herein will enhance the
information and facilitate the evaluation of skeletal maturation
determinations. The graphic representation of successive reports clearly
depicts whether values retain their position in relation to the mean
(Fig. 1). In addition, the
report includes computation of exact SD scores rather than the range in which
they lie. When values do not track and cross the SD, radiologists will be
encouraged to reassess previous interpretations before finalizing their
reports.
Bone age reports, like those for height, weight, and body mass index, would
benefit from a graphic representation. A limitation of these bone age charts
is that the SD scores were derived from the Greulich and Pyle atlas
[1], which was based on a study
by T. Wingate Todd of a limited group of subjects who were primarily white,
middle-class children from northeastern Ohio. In contrast, the Centers for
Disease Control and Prevention provided comprehensive growth charts relative
to the third or fifth, 10th, 25th, 50th, 75th, 90th, and 95th or 97th
percentiles based on a large cohort of normal children representing the
population of the United States
[2]. This limitation, however,
applies to all interpretations conducted according to the method of Greulich
and Pyle, regardless of whether they are or are not represented
graphically.
Several automated methods to facilitate the analysis of skeletal maturity
are currently available [3,
4]. However, regardless of the
method used, bone age determinations are reported in the context of numeric
data indicating the difference in SD scores between the patient's bone age and
chronologic age. We developed a simple automated method to graphically
represent the bone ages of children to enhance the information and facilitate
the evaluation of skeletal maturation determinations, especially when frequent
assessments are made. Since January 2007, bone age charts generated by this
program have been digitally integrated into the Patient Centric Information
Management System (PCIMS) of the UCLA Healthcare and are part of the permanent
medical records of our patients.
References
- Greulich WW, Pyle SI. Radiographic atlas of skeletal
development of the hand and wrist, 2nd ed. Stanford, CA: Stanford
University Press, 1959:1
–60
- Hamill PV, Drizd TA, Johnson CL, Reed RB, Roche AF, Moore WM.
Physical growth: National Center for Health Statistics percentiles.
Am J Clin Nutr 1979;32
: 607–629[Abstract/Free Full Text]
- Zhang A, Gertych A, Liu BJ. Automatic bone age assessment for young
children from newborn to 7-year-old using carpal bones. Comput Med
Imaging Graph 2007; 31:299
–310[CrossRef][Medline]
- Gertych A, Zhang A, Sayre J, Pospiech-Kurkowska S, Huang HK. Bone
age assessment of children using a digital hand atlas. Comput Med
Imaging Graph 2007; 31:322
–331[CrossRef][Medline]
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Abstract
Introduction
