Yonago Acta medica 1997;40:31–42

A Study on Echogenic Changes of the Kidney-Spleen and Liver-SpleenContrasts with Age in Infants and Children
Md. Abdus Samad, Hiroshi Hayashibara, Yasushi Utsunomiya and Kazuo Shiraki
Department of Pediatrics, Faculty of Medicine, Tottori University, Yonago 683, Japan
Individual echogenicities of the kidneys and liver cannot be determined using only thegenerally accepted right kidney/liver contrast ratio. We therefore determined 5 newcontrast ratios: i) left kidney to spleen (Kl/SP); ii) right kidney to spleen (Kr/SP); iii)
liver to spleen (L/SP); iv) Kl/SP – Kr/L; and v) (Kl/SP)/(Kr/L); with the last 2 being
designated as modified ratios alternative to the L/SP ratio. We used the new ratioswith computerized histogram sonography to assess echogenicitic changes in the kidneys,
liver and spleen with age for 257 normal children ranging from birth to 15 years old.
The values in Kr/L, Kl/SP and Kr/SP increased from day 0 to day 2 in early neonates(values > 1), decreased between day 2 to 1 month, and thereafter remained constant.
The values were < 1 from 1 month to 15 years. The values in L/SP ratio were constantfrom birth through 6 months (values > 1), and thereafter decreased gradually to avalue of approximately 1 and remained constant in the later periods. We found therelationship Kl/SP < Kr/L in early neonates, Kl/SP > Kr/L in infants and Kl/SP < Kr/L
again in the later periods. These results suggest that the renal cortical echogenicity was
higher than that of the liver and splenic parenchyma in early neonates and that theechogenicity of the liver was greater than that of the spleen in children from birth to 6
months. Combining these ratios is thus helpful for assessing renal and hepatic
echogenicity individually. Moreover, significantly higher echogenicity of the liver wasobserved in patients with hepatic dysfunction (n = 21) for children of all age groups, as
observed by the L/SP contrast ratio. Significantly increased echogenicity of the liver
was observed by modified ratios in children aged 1 year or older. We suspect that the
L/SP and modified ratios are useful for assessing the echogenicity of the liver in patientswith liver dysfunction.
Key words: childhood; computerized histogram sonography; liver; kidneys; spleen

It is well established that the liver-kidney
contrast by echographic findings varies until 2
to 3 months after birth and thereafter becomes
constant, although a few authors have suggested that the period of variation lasts as longas 6 months (Haller et al., 1982; Han andBabcock, 1985) or even 1 year (Winkler andAltrogge, 1985). Using sonography, Hricak
and colleagues (1983) observed the features ofan adult kidney as early as the 2nd year of life,
and attributed this to the gradual change of theneonatal kidney. This concept is well supportedby the general belief that liver-kidney echogenicity remains unchanged after a certain
period. But determination of the echogenicityof the kidneys is encumbered by inherent
limitations—the standard to which the kidney iscompared may not be normal itself—and a

Abbreviations: Kl < Kr, left renal echogenicity < right renal echogenicity; Kl/SP, left kidney to spleen; Kl/SP– Kr/L, Kl/SP minus Kr/L; (Kl/SP)/(Kr/L), Kl/SP divided by Kr/L; Kr/L, right kidney to liver; Kr/SP, rightkidney to spleen; L > SP, hepatic echogenicity > splenic echogenicity; L/SP, liver to spleen; ROI, region ofinterest; SGPT,serum glutamic-pyruvic transaminase; SGOT, serum glutamic-oxaloacetic transaminase; SP> L, splenic echogenicity > hepatic echogenicity

31

M. A. Samad et al.

Table 1. The values of echointensity in 6 contrast ratios in different childhood age groups(birth to 15 years) in normal children (n = 257)
Age group
Kr/L

Kl/SP

Contrast ratio
Kr/SP
L/SP

Kl/SP – Kr/L

(Kl/SP)/(Kr/L)d0[16] 1.084±0.164 1.037±0.186 1.185±0.278 1.092±0.189 –0.047±0.244 0.978±0.237
d2[17] 1.211±0.175 1.129±0.169 1.332±0.224 1.110±0.177 –0.082±0.217 0.946±0.172d5[15] 1.072±0.124 0.977±0.167 1.207±0.140 1.137±0.169 –0.095±0.227 0.927±0.216m1[40] 0.918±0.195 0.938±0.213 0.994±0.261 1.096±0.235 0.020±0.276 1.059±0.288
m3–4 [23] 0.873±0.150 0.872±0.163 0.959±0.234 1.100±0.206 –0.001±0.192 1.019±0.227
m5–6 [ 6] 0.839±0.124 0.886±0.135 0.885±0.072 1.081±0.244 0.047±0.189 1.082±0.273
m7–8 [ 5] 0.853±0.170 0.834±0.167 0.772±0.086 0.918±0.100 –0.019±0.291 1.023±0.355
m9–11 [12] 0.797±0.089 0.886±0.118 0.826±0.157 1.034±0.126 0.089±0.154 1.126±0.210
y1–2 [17] 0.857±0.130 0.889±0.156 0.858±0.189 1.011±0.219 0.032±0.210 1.060±0.255
y3–4 [15] 0.871±0.169 0.855±0.171 0.876±0.178 1.018±0.160 –0.017±0.092 0.989±0.117
y5–6 [21] 0.901±0.212 0.828±0.139 0.788±0.181 0.909±0.272 –0.073±0.289 0.974±0.292
y7–8 [13] 0.883±0.146 0.883±0.188 0.928±0.203 1.070±0.287 –0.000±0.285 1.042±0.359
y9–10 [13] 0.871±0.265 0.916±0.164 0.904±0.221 1.061±0.190 0.045±0.206 1.101±0.263
y11–13 [16] 0.869±0.126 0.836±0.113 0.792±0.146 0.915±0.131 –0.034±0.111 0.971±0.123
y13–15 [28] 0.914±0.220 0.895±0.152 0.878±0.213 0.973±0.204 –0.019±0.187 1.002±0.082
Mean ± SD.
[ ], number of subjects.
Kl/SP, left kidney to spleen; Kl/SP – Kr/L, Kl/SP minus Kr/L; (Kl/SP)/(Kr/L), Kl/SP divided by Kr/L; Kr/L,
right kidney to liver; Kr/SP, right kidney to spleen; L/SP, liver to spleen.
d0, 0 day old; d2, 2 days old; d5, 5 days old; m1, 1 month old; m3–4, 3 to 4 months old; m5–6, 5 to 6 months
old; m7–8, 7 to 8 months old; m9–11, 9 to 11 months old; y1-2, 1 to 2 years old; y3–4, 3 to 4 years old; y5–6,
5 to 6 years old; y7–8, 7 to 8 years old; y9–10, 9 to 10 years old; y11–12, 11 to 12 years old; y13–15, 13 to 15
years old.

Simpson, 1957; Rosenfield et al., 1980). Other
biological components, such as fat, calcium,proteins, the volume of cellular elements,
hepatic perfusion, etc. (Rosenfield et al., 1980),
may play important roles in echogenic variation
with age. Clearly, it is rather difficult to construct a rigid contrast ratio, and by using only
the generally accepted liver and kidney contrast, we cannot determine the variation in echogenicity for different childhood age groups. It
is therefore necessary to establish the actual
parameters of kidney and liver echogenicity invarious childhood age groups.
To this end, we determined the i) rightkidney to spleen (Kr/SP); ii) left kidney tospleen (Kl/SP); iii) liver to spleen (L/SP); iv)
Kl/SP – Kr/L; and v) (Kl/SP)/(Kr/L) ratios forthe purpose of establishing the changes in echogenicity of the liver and kidney individually.
Kl/SP – Kr/L and (Kl/SP)/(Kr/L) are modified
ratios alternative to the L/SP.

standard reference for kidneys is needed. If, inlate childhood and adult life, the kidney is of thesame echogenicity as the liver, this should not
be considered an indicator of renal disease(Eggert et al., 1991). In fact, the idea that hepatic echogenicity remains constant is still only anassumption. The physiological increase inechogenicity of the liver may be disguised bypathological causes (Eggert et al., 1991). Or theechogenicity of the liver and kidneys may varywith certain physiological and pathologicalchanges, e.g., primary viral infections of theliver and kidneys, physiological hepatomegalyin early infants, or quantitative changes in renal
anatomy in early infants (Hricak et al., 1983).
Structural collagenous changes also have an
impact on echogenicitic changes within theseorgans during physiological processes(Harkness and Nightingale, 1962; Harkness andHarkness, 1963; Fields and Dunn, 1973;
Rosenfield et al., 1980), as well as duringpathological processes (Fields and Dunn, 1973;32

Echogenic changes with age in children

Subjects and Methods

supine positions in the longitudinal plane. In
the case of neonates, the babies were placed in
the supine position and then rotated into a rightlateral position with the transducer movingfrom back to front as the spleen and left kidney
were adequately visualized. Newborn babies
were examined in an incubator with minimal
handling and disturbance. Babies were kept
warm by radiant heat lamps. No sedation wasused. Two people were present at the time ofthe study. One assisted by restraining the baby
while the other scanned. The neonates wereplaced in a supine or decubitus position for
examination of the left kidney and spleen, andthis position was maintained for the rightkidney and liver. The 5.00 MHz transducer wasfavored as the standard choice (Frank et al.,1979).
The histogram analysis with region of interest (ROI) was used for measuring the intensities
of echogenicity. The relative number of echoesof given intensities were plotted on the verticalaxis against the varying levels of echobrightness on the horizontal axis. The histogram
ROIs were placed closely in the most clear andhomogeneous areas of the hepatic parenchyma,
renal cortex and splenic parenchyma, as theseregions were nearly equidistant from the transducer (Fig. 1). Because placing an object
within the near or far field of the transducer
may alter echogenic properties (Carson andOughton, 1977; Taylor et al., 1979; Jaffee andTaylor, 1979), we selected a transducer thatwould include the area to be studied within the
focal zone of the transducer.

Sonograms were performed in 278 male andfemale children from 0 to 15 years of age at theout- and inpatient departments of our hospital.
Among the 278 children, 257 were normal and
21 were patients with hepatic dysfunction. Informed, written consent was obtained from theparents or guardians of each subject prior to thesonogram study. Children were considered
normal if they only showed signs of hepatomegaly, but were negative for both hepatic dysfunction (laboratory evidence) and kidneydiseases (clinical and/or laboratory evidence).
Hepatic dysfunction was defined in 21 cases bya steep rise in serum transaminases. Of the 257
normal children examined, 68 were neonates,
and the rest were non-neonates. Correlation
with clinical status (hematuria, proteinuria,
hepatomegaly, jaundice) and laboratory data
[blood urea nitrogen, serum creatinine, serum
glutamic-pyruvic transaminase (SGPT) andserum glutamic-oxaloacetic transaminase(SGOT)] served as the basis for defining therenal and hepatic status of each patient. Renalfunction was considered abnormal if the serum
creatinine level exceded 1.0 mg/dL. Liverfunction abnormality was based on SGPT and
SGOT of greater than 47 IU/L. We divided
neonates into 3 age groups: 0 day of birth (d0),
2nd day of birth (d2) and 5th day of birth (d5);and the non-neonates into 12 age groups: 1
month (m1), 3 to 4 months (m3–4), 5 to 6
months (m5–6), 7 to 8 months (m7–8), 9 to 11
months (m9–11), 1 to 2 years (y1-2), 3 to 4
years (y3–4), 5 to 6 years (y5–6), 7 to 8 years(y7–8), 9 to 10 years (y9–10), 11 to 12 years(y11–12) and 13 to 15 years (y13–15) (Table 1).
We used an ultrasonogram machine
ALOCA SSD 670 with either 5.00 or 3.5 MHz
transducers of a convex type. A 5.00 MHz
transducer was used in neonates and young
children of small body size and a 3.5MHz
transducer in older children, and young childrenof large body size. Gain settings and Sensitivity
Time Control (STC) were adjusted and kept
constant for the most satisfactory visualizationof parenchyma of the organs throughout eachexamination. All patients were scanned in

Histogram analysis
The histograms represent the echo-distribution
intensity of the ROI area. The horizontal axis
represents 0 to 63 shades of gray, and thevertical axis the distribution ratio of each shade.
Here the number of picture elements (pixels) of
the most common shades in the ROI areas wereassumed to be 100%. (T, total number of pixels
in ROI; L, gray scale level of shade component
that is most common in the ROI; M, number ofpixels of the shade component that is mostcommon in the specified area).
33

M. A. Samad et al.

1A

1B

Statistical analysis

L in the histogram of the left kidney

All data were expressed asmean ± SD. Differences between the variables in multiple groups were assessed using both parametric and nonparametric analyses due to an
insufficient number of data.
One-way analysis of varianceand a post hoc test [Fisher’sProtected Least Significant
difference (PLSD) method]
was used to calculate between
the 2 variables in multiple
groups. Differences between
more than 2 groups (multiple
groups) were assessed using
the Kruskal-Wallis test. Student’s t-test was used to compare between patients withliver dysfunction and normal
controls. Correlations between
variables were performed byregression analysis. A valueof P < 0.05 was considered significant.

Fig. 1. A computerized histogram analysis of the right renal cortex,
liver and splenic parenchyma by longitudinal scan. A: The portion of
the left renal cortex and splenic parenchyma that is of interest isdemarcated by a circle. The regions of interests (ROIs) are placed in theleft renal cortex and splenic parenchyma at the same distance from thetransducer. B: The portion of the right renal cortex and hepatic
parenchyma that is of interest is demarcated by a circle. The ROIs areplaced in the right renal cortex and hepatic parenchyma at the same
distance from the transducer.

Results

Correlations in echogenicity between
the right and left kidneys

y = 5.604 + 0.687 × x
r = 0.752
P < 0.0001

4035

In non-neonates (n = 209), statistically significant correlation in echogenicity was foundbetween right and left kidneys (r = 0.752) (Fig.
2). In early neonates (n = 48), there was nocorrelation between the echogenicity of theright and left kidneys (r = 0.075) (Fig. 3)

30
25
20
15
10

Correlations in echogenicity between
the liver and spleen

5
0
0

5

10

15

20

25

30

35

40

A significant correlation was found between theechogenicity of liver and spleen in non-neonatal
children (r = 0.677) (Fig. 4). A weak correlation was seen between the echogenicity of liverand spleen in early neonates (r = 0.334) (Fig. 5).
No significant differences in echogenicity were
found between males and females.

L in the histogram of the right kidney
Fig. 2. Relationship in echogenicity between the left
and right renal cortices during the non-neonatal period. L, the gray scale level of the shaded component
that is most common in ROI; , L in the histogramof the left and right renal cortices.

34

40
35

y = 6.995 + 0.657 × x
r = 0.677
P < 0.0001

40

y = 18.678 + 0.076 × x
r = 0.075

L in the histogram of the spleen

L in the histogram of the left kidney

Echogenic changes with age in children

30
25

20
15

10

5

0

35

30

25

20

15

10

5

0
0

5

10

15

20

25

30

35

0

40

5

10

25

20

15

30

35

40

L in the histogram of the right kidney

L in the histogram of the liverFig. 3. Relationship in echogenicity between left
and right renal cortices during the early neonatal
period. L, the gray scale level of the shaded component that is most common in ROI; , L in thehistogram of the left and right renal cortices.

Fig. 4. Relationship in echogenicity between
hepatic and splenic parenchyma during the nonneonatal period. L, the gray scale level of the shaded
component that is most common in ROI; , L in thehistogram of the hepatic and splenic parenchyma.

The Kr/L contrast ratio in normal children

Kruskal-Wallis test. Significant changes were also
observed between d0 and d2 (P < 0.05); d0 andeach group of months and years (P < 0.01); d2 andd5 (P < 0.05); d2 and each group of months andyears (P < 0.001); and d5 and each of thefollowing: m3–4, m5–6, m7–8, m9–11, y1–2,
y3–4, y5–6 and y7–8 (P < 0.01) as analyzed by the
Fisher PSLD test.

The Kr/L contrast ratio in normal children (n =257) increased from d0, peaked at d2, decreased
until 1 month of age, and thereafter became
constant (Fig. 6). The average value was higher
than 1 between d0 to d5 and lower than 1 between
m1 to 15 years. Statistically significant changes
were seen from birth to 15 years (P < 0.001) by the

P < 0.001*
P < 0.001*

y =13.289 + 0.298 × x
r = 0.334
P = 0.0199

35

1.4

Kr/LKr/L

40

30

25

1.2

1.0

0.8

0.6

20

0.4

–1
1

5
–1
y13 2
–1
y11
10
y9–
8
y7–
6
y5–
4
y3–

m9

–8
–6

2

m7

–4

10

y1–

m5

m1

m3

d5
d2

15

d0

L in the histogram of the spleen

1.6

Age group
5

0
0

5

10

15

20

25

30

35

40

L in the histogram of the liverFig. 5. Relationship in echogenicity between
hepatic and splenic parenchyma during the earlyneonatal period. L, the gray scale level of theshaded component that is most common in ROI;
, L in the histogram of the hepatic and splenicparenchyma.

Fig. 6. Echointensity of the right renal cortex andhepatic parenchyma in the Kr/L contrast ratio versus
different childhood age groups: d0, 0 days old; d2, 2
days old; d5, 5 days old; m1, 1 month old; m3–4, 3 to 4
months old; m5–6, 5 to 6 months old; m7–8, 7 to 8
months old; m9–11, 9 to 11 months old; y1-2, 1 to 2
years old; y3–4, 3 to 4 years old; y5–6, 5 to 6 years old;y7–8, 7 to 8 years old; y9–10, 9 to 10 years old; y11–12,
11 to 12 years old; y13–15, 13 to 15 years old. *KruskalWallis test.

35

M. A. Samad et al.

P < 0.001*

1.6

P < 0.001*

The Kl/SP contrast ratio in normalchildren

1.4

Kl/SP

1.2

1.0

0.8

0.6

0.4

4

2

5
–1
y13 2
–1
y11
10
y9–
8
y7–
6
y5–

y3–

–1

y1–

m9

–8

–6

–4

m7

m5

m3
m1

d5
d2
d0

1

Age group
Fig. 7. Echointensity of the left renal cortex and splenicparenchyma in the Kl/SP contrast ratio versus different
childhood age groups: age classification is the same asin the legends to Fig. 6. *Kruskal-Wallis test.
P < 0.05*
P < 0.001*

1.6

Kr/SP

1.4

1.2

1.0

0.8

The Kr/SP contrast ratio in normalchildren

0.6

0.4

4

2

5
–1
y13 2
–1
y11
10
y9–
8
y7–
6
y5–

y3–

–1

y1–

m9

–8

–6

–4

m7

m5

m3
m1

d5
d2
d0

1

Age group

Fig. 8. Echointensity of the right renal cortex andsplenic parenchyma in the Kr/SP contrast ratio versus
different childhood age groups: age classification is thesame as in the legends to Fig. 6. *Kruskal-Wallis test.

P < 0.05*
P < 0.01*

1.6

1.4

L/SP

The values of this ratio increased fromd0, peaked at d2 and decreased until 1month of age (n = 257) (Fig. 7). After 1
month, the values became constant. The
average value was greater than 1 between
d0–d2, equal to 1 at d5, and less than 1
between m1–15 years. Statisticallysignificant changes were seen from birth
to 11 months (P < 0.001), and from birth
to 15 years (P < 0.001) analyzed by the
Kruskal-Wallis test. Significant changes
were seen between d0 and m1 (P < 0.05);
d0 and each of the following: m3–4, m7–
8, m9–11, y1–2, y3–4, y5–6, y7–8 andy11–12 (P < 0.01); d2 and d5 (P < 0.05);
and d2 and each group of months andyears (P < 0.01) by the Fisher PSLD test.

1.2

1.0

0.8

0.6

0.4

8

10

5
–1
y13 2
–1
y11

y9–

4

6

2

1

y7–

y5–

y3–

–1

y1–

m9

–6

–8

–4

m7

m5

m3
m1

d5
d2
d0

Age group

Fig. 9. Echointensity of the hepatic and splenicparenchyma in the L/SP contrast ratio versus different
childhood age groups: age classification, the same as in
the legends to Fig. 6. *Kruskal-Wallis test.

36

The values of this ratio increased fromd0, peaked at d2, and decreased until 1month of age (n = 257) (Fig. 8). After 1
month, the values became constant. The
average value was greater than 1 between
d0 to d5, and less than 1 between m1 to15 years. Significant changes were seenfrom birth to 15 years (P < 0.001), andfrom 1 month to 15 years (P < 0.05) asanalyzed by the Kruskal-Wallis test.
Significant changes were found between
d0 and d2 (P < 0.05); d0 and each groupof months and years (P < 0.01); d2 andeach group of months and years (P <0.001); d5 and each group (except m5–6)
of months and years (P < 0.001); m1 andeach of the following: m7–8, y1–2, y5–
6, y11–12 and y13–15 (P < 0.05); andm3–4 and each of these: y5–6, y11–12(P < 0.05) as analyzed by the Fisher
PSLD test.

Echogenic changes with age in children

NS*

Kl/SP – Kr/L

0.4

0.2

0.0

–0.2

–0.4

–4

5
–1
y13 2
–1
y11
10
y9–
8
y7–
6
y5–
4
y3–
2
y1–
1
–1
m9
–8
m7
–6
m5

m1

m3

d5

d2

d0

Age group
Fig. 10. Echointensity of the hepatic and splenicparenchyma in the Kl/SP – Kr/L contrast ratio versus
different childhood age groups: age classification is thesame as in the legends to Fig. 6. *NS, not significant instatistical difference with the Kruskal-Wallis test.

The L/SP contrast ratio in normal children
The values of this ratio increased from birththrough 6 months and decreased at 7 to 8 months (n= 257) (Fig. 9). After that, the values increasedslightly and became constant later on. The averagevalue was greater than 1 between birth to 6 months,
and almost equal to 1 in the later period.
Statistically significant changes were observed
between birth to 15 years (P < 0.05); 1 month to 15
years (P < 0.01) as analyzed by the Kruskal-Wallis
test. Significant changes were also observed

1.6

NS*

(Kl/SP)/(Kr/L)

1.4

between d0 and y5–6 and y11–12 each (P <0.05); d2 and y5–6, y11–12 and y13–15
each (P < 0.05); d5 and m7–8, y5–6, y11–
12 and y13–15 each (P < 0.05); m1 and y5–
6, y11–12 and y13–15 each (P < 0.05); m3–
4 and y5–6, y11–12 and y13–15 each (P <0.05); and y5–6 and y7–8, y9–10 and y11–
12 each (P < 0.05) as analyzed by theparametric test (Fisher PSLD method).
Inconsistent results were observed forcorrelations in echogenicity between thekidneys (left and right) as well as between
the liver and spleen in the early neonatal
period. Thus, the accuracy of the L/SP ratio
result in which hepatic echogenicity was
higher than splenic in the early neonatal
period is open to question. To resolve these
discrepancies for echogenicity in the earlyneonatal period we produced 2 modified
ratios, Kl/SP – Kr/L and (Kl/SP)/(Kr/L).

The Kl/SP – Kr/L contrast ratio in
normal children
We observed that the results for echogenicity was Kl/SP < Kr/L in early neonates
and Kl/SP > Kr/L in the infantile period (n= 257) (Fig. 10). After the infantile period
we again observed that the echopattern was
Kl/SP < Kr/L, and that this patterncontinued in the later periods. Significant
changes were found between d2 and m9–
11; d5 and m9–11; and m9–11 and y5–6 (P< 0.05) by the Fisher PSLD test.

1.2

The (Kl/SP)/(Kr/L) contrast ratio in
normal children

1.0

0.8

0.6

0.4

1

5
–1
y13 2
–1
y11
10
y9–
8
y7–
6
y5–
4
y3–
2

–1

y1–

m9

–6

–8

–4

m7

m5

m3
m1

d5
d2
d0

Age group
Fig. 11. Echointensity of the hepatic and splenicparenchyma in the (Kl/SP)/(Kr/L) contrast ratio versus
different childhood age groups: age classification, thesame as in the legends to Fig. 6. *NS, not significant instatistical difference with the Kruskal-Wallis test.

37

The result for echogenicity in this ratio wassimilar to that in the Kl/SP – Kr/L contrast
ratio (n = 257) (Fig. 11). Statisticallysignificant differences were found between
d2 and m9–11; and d5 and m9–11 (P <0.05) by the Fisher PSLD test.

M. A. Samad et al.

All age groups

1 year of age

All age groups< 1 year of age

1 year of age

P < 0.01

P < 0.05
0.4

P < 0.05

NS

1.4

Kl/SP – Kr/L

1.5

L/SP

1.3
1.2

E

1.1

E

1.0

E

0.7

NS

NS

0.2

E

0.0

E

E

–0.2

0.9
0.8

< 1 year of age

1.140 ± 0.227
1.198 ± 0.291
1.086 ± 0.144
1.026 ± 0.212
0.997 ± 0.208
1.108 ± 0.199
[21]
[78]
[10]
[59]
[11]
[20]

–0.4

0.066 ± 0.215
0.114 ± 0.252
0.022 ± 0.175–0.006 ± 0.182–0.020 ± 0.181
0.036 ± 0.187
[21]
[78]
[10]
[59]
[11]
[20]

0.6

+

–

+

–

+

+

–

Liver dysfunction

–

+

–

+

–

Liver dysfunction
Fig. 13. Difference in echogenicity of the hepatic
parenchyma in the Kl/SP – Kr/L contrast ratio
between patients with hepatic dysfunction ( ) andnormal controls ( ). Children of all age groups (left),children aged 1 year or older (middle) and children
younger than 1 year (right). +, hepatic dysfunction; –,no hepatic dysfunction. [ ], number of subjects.

Fig. 12. Difference in echogenicity of the hepatic
parenchyma in the L/SP contrast ratio between
patients with hepatic dysfunction ( ) and normal
controls ( ). Children of all age groups (left),children aged 1 year or older (middle) and children
younger than 1 year (right). +, hepatic dysfunction;–, no hepatic dysfunction. [ ], number of subjects.

In the (Kl/SP)/(Kr/L) contrast ratio: The
result in this ratio was similar to that found in
Kl/SP–Kr/L ratio (Fig. 14).

Echogenicitic changes of the liver in patients with hepatic dysfunction and normal controls
In the L/SP contrast ratio: A statisticallysignificant difference in the echogenicity of theliver was observed between patients with hepatic dysfunction (n = 21) and normal controls (n =79) (P < 0.05) in children of all age groups (Fig.
12). A significant difference in echogenicity ofliver was observed between patients with hepatic dysfunction (n = 10) and normal controls (n =59) in children aged 1 year or older (P < 0.01),
but no significant difference was observed between the hepatic dysfunction (n = 11) andnormal controls (n = 20) in children aged lessthan 1 year.

In the Kr/L contrast ratio: No statisticallysignificant difference in the echogenicity of theliver was seen between the patients with hepatic
dysfunction and normal controls (Fig. 15).

Discussion
Ultrasonography is being utilized with increasing frequency to evaluate renal and hepatic
parenchymal diseases in both children andadults (Gosink et al., 1979; Joseph et al., 1979;
Kurtz et al., 1980; Henschke et al., 1982;
Winkler and Altrogge, 1985; Benbridge et al.,
1986; Platt et al., 1988; Kraus et al et al., 1990).
A number of previous articles have assessedchildhood kidney and liver sizes (Wladimiroff
and Sekeris, 1976; Haugstvedt and Lundberg,
1980; De Vries and Levene, 1983; Dinkel et al.,
1985; Scott et al., 1990; Gupta et al., 1993) andvolumes (Holloway et al., 1983; Chiara et al.,
1993; Sargent and Gupta, 1993). To our know-

In the Kl/SP–Kr/L contrast ratio: A statistically significant difference in the echogenicityof the liver was seen between normal controls
and patients with hepatic dysfunction inchildren aged 1 year or older (P < 0.05), but thisdifference was absent in children aged less than
1 year (Fig. 13). Differences were analyzed byStudent’s t-test.
38

All age groups

1 year of age< 1 year of age

All age groups

1 year of age< 1 year of age

NS

NS

NS

P < 0.05
1.5

NS

1.4

1.4

NS

1.3

1.3

1.2

1.2

Kr/L

(Kl/SP)/(Kr/L)

1.5

1.1

E

1.0

E

E

0.7

1.1
1.0
0.9

0.9
0.8

1.140 ± 0.227
0.831 ± 0.151
0.842 ± 0.228
1.026 ± 0.212
0.887 ± 0.213
0.839 ± 0.112
[21]
[78]
[10]
[59]
[11]
[20]

–

+

–

+

E

0.7
0.6

0.6

+

E

E

0.8

1.115 ± 0.267
1.184 ± 0.330
1.053 ± 0.187
1.016 ± 0.202
1.002 ± 0.193
1.058 ± 0.224
[21]
[78]
[10]
[59]
[11]
[20]

+

–

Liver dysfunction

–

+

–

+

–

Liver dysfunction

Fig. 14. Difference in echogenicity of the hepatic
parenchyma in the (Kl/SP)/(Kr/L) contrast ratio
between patients with hepatic dysfunction ( ) andnormal controls ( ). Children of all age groups (left),children aged 1 year or older (middle) and children
younger than 1 year (right). +, hepatic dysfunction; –,no hepatic dysfunction. [ ], number of subjects.

Fig. 15. Difference in echogenicity of the hepatic
parenchyma in the Kr/L contrast ratio between
patients with hepatic dysfunction ( ) and normal
controls ( ). Children of all age groups (left),children aged 1 year or older (middle) and children
younger than 1 year (right). +, hepatic dysfunction;–, no hepatic dysfunction. [ ], number of subjects.

ledge, however, no assessment has been madeon changes in the echogenicity of liver andrenal parenchyma over a broad time span inchildhood (e.g., birth to 15 years). Our study
was designed to determine the changes in echogenicity of the liver and renal parenchyma bycomputerized histogram sonography in normalchildren of various age groups, thus allowing
the identification of variances from the normal.
We also used this technique to evaluate theechogenicity of the liver in patients with hepatic
dysfunction and in normal controls. Echogenicitic assessments of the renal cortex by the
Kr/L contrast have already been presented inseveral reports (Haller et al., 1982; Hayden etal., 1984; Erwin et al., 1985; Han et al., 1985;
Cramer et al., 1986). Hepatic parenchymal
echogenicity, to which renal cortical echogenicity is compared in this study, has beentaken as the standard in several studies using the
KR/L contrast ratio. However, it is difficult toevaluate the renal echogenicity without knowing the hepatic echogenicity. We therefore used
5 new parameters to investigate the echogenicity of the liver and kidneys individually.
Our results showed a positive correlation inechogenicity between the left and right non-neonatal kidneys (Fig. 2), which was consistent
with the results of previous studies (Han andBabcock, 1985; Emamian et al., 1993). This
study was unable to show a correlation inechogenicity between the left and right earlyneonatal kidneys (Fig. 3). The cause of these
discrepant results for the early neonatal period
are unknown to us, though a few factors might
possibly be implicated: i) inadequate visualization of the left kidney; ii) inconsistent renal
perfusions (left and right); and iii) the differences in body positions and body-wall thickness. The inadequate visualization of the left
kidney might further be associated with large
stomach size, overdistention of the intestines,
overcrowding of the ribs, and the short time
permitted for echography, etc. A few studies
have reported technical difficulties in performing sonography in neonatal babies (e.g., Franket al., 1979), but we could find no similar reports on perfusion distributions to the earlyneonatal kidneys. An extensive study is neededin this area.
Our present study shows that renal corticalechogenicity (left and right) was greater thanthat of the hepatic and splenic parenchyma(Figs. 6, 7 and 8) during the early neonatal
39

M. A. Samad et al.

period, and that with the infant’s growth it thenprogressed through a predictable change fromincreased echogenicity to echogenicity lessthan that of the liver and spleen. It should be
noted that no patients in our study manifested
renal disease, hypertension, sepsis or hypoxemia, so these factors cannot, therefore, be
implicated in the increased echogenicity. The
above results are in contradiction to previously
published reports using the generally accepted
Kr/L ratio. Hricak and coworkers (1983) and
Hayden and colleagues (1984) stated that renal
cortical echogenicity was normally as echogenic as the liver parenchyma during the neonatal and young infantile period. Han andBabcock (1985) compared the echogenicity of
the kidneys (left and right) with that of the liverand spleen in 122 children (newborn to 17 years
old) and were not able to show that the neonatal
renal cortical echogenicity was greater. Theseprior authors used only naked-eye evaluation todetermine echogenicity. Eggert and coworkers(1991) proved by a densitometric study in infants that naked-eye evaluation did not permit aclear distinction between the categories of
echogenicity, and also that the assessment of individual examiners varied considerably. Our
ultrasound study was performed by computerized histogram analysis. To our knowledge,
very few data on histogram sonography havebeen published until recently. Rosenfield andSiegel (1981) studied medical renal diseases bycomputerized histogram sonography, andgraded renal cortical echogenicity by comparing the amplitude of echoes in the renal cortex
with that of the liver, spleen and renal sinus.
Bondestam and others (1992) examined the correlations of liver echointensity with cytology
and chemical measurements of fat, water andprotein content in live burbots (lota lota) fish byusing computerized histogram sonography.
In the L/SP contrast ratio, we observed thatthe echogenicity of the liver was higher thanthat of the spleen from birth through 6 months,
after which it gradually decreased till it was
equal to that of the spleen (Fig. 9). We wereuncertain of the accuracy of results concerning
the echogenicity of the liver and spleen in the L/
SP contrast ratio in early neonates. Factors

such as weakly correlated echogenicity between the liver and spleen (Fig. 5), or negatively correlated echogenicity between the left andright kidneys during the early neonatal period(Fig. 3) might have contributed to these ambiguous results. To resolve such a discrepant
relationship in echogenicity between the left
and right kidneys in the early neonatal period,
we produced 2 modified ratios, Kl/SP – Kr/Land (Kl/SP)/(Kr/L). The results for echogenicity of the liver and spleen in modified ratios
was SP > L or Kl < Kr in the early neonatal period (Fig. 10). If the result for echogenicity of theliver and spleen in the L/SP contrast ratio, i.e., L> SP, was true in the early neonatal period, thenwe can say the result observed in modified
ratios was Kl < Kr. A good correlation between
the echogenicities of the kidneys of the left andright sides (Fig. 2), as well as between those of
the liver and spleen did in fact exist in the nonneonatal period (Fig. 4). Therefore, the resultsfor echogenicity of the liver and spleen in L/SP
(Fig. 9), as well as in modified ratios (Figs. 10
and 11) during the non-neonatal period can be
accepted as reliable. A study regarding perfusion distribution to the kidneys in the earlyneonatal period is needed. The result obtainedin the L/SP ratio for echogenicity of the liverand spleen (Fig. 9) was in good agreement withprevious findings that the liver is always higher
in intensity than the spleen (Rosenfield et al.,
1981; Sanders, 1991). Emamian and workers(1993) showed that the echogenicity of thespleen in young adults was higher than that of
the liver. Our results in modified ratios werepartially consistent with the reports of Emamian
and workers, but further studies will be neededin this regard.
The results for our new ratios measured bycomputerized histogram sonography revealed
that the echogenicity of the liver was significantly higher in patients with hepatic dysfunction (serum transaminases more than 47 IU/L)
than that of normal controls (serum transaminases within normal limits). It should be
noted that a significantly increased echogenicity of the liver was found in the L/SP ratio
in children aged from birth through 15 years(Fig. 12), but only in children of age 1 year or
40

Echogenic changes with age in children

5 Chiara A, Chirico G, Barbarini M, De Vecchi E,
Rondini G. Ultrasonic evaluation of kidney
volume in term and preterm infants. AJR Am J
Roentogenol 1993;10:109–111.
6 Cramer BC, Jequier S and De Chadarevian JP.
Factors associated with renal parenchymal echogenicity in the newborn. J Ultrasound Med 1986;
5:633–638.
7 Dinkel E, Ertel M, Dittrich M, Peters H, Berres
M, Wissermann SH. Kidney size in childhood.
Sonographical growth chart for kidney length andvolume. Pediatr Radiol 1985;15:38–43.
8 De Vries L, Levene MI. Measurement of renal
size in preterm and term infants by real time
ultrasound. Arch Dis Child 1983;58:145–147.
9 Eggert P, Debus F, Laugwitz GK, Oppermann
HC. Densitometric measurement of renal echogenicity in infants and naked eye evaluation: acomparison. Pediatr Radiol 1991;21:111–113.
11 Emamian SA, Nielsen MB, Pedersen JF, Ytte L.
Sonographic evaluation of renal appearance in
665 adult volunteers. Correlation with age andobesity. Acta Radiol 1993;34:482–485.
10 Erwin BC, Carroll BA, Muller H. A sonographic
assessment of neonatal renal parameters. J
Ultrasound Med 1985;4;217–220.
12 Fields S, Dunn F. Correlation of echographic
visualizability of tissue with biological composition and physiological state. J Acoust Soc Am
1973;54:809–812.
13 Frank JL, Potter BM, Shkolnik A. Neonatal
Urosonography. Clin Diag Ultrasound 1979;2:
159–174.
14 Gosink BB, Lemon SK, Scheible W, Leopold
GR. Accuracy of ultrasonography in diagnosis ofhepatocellular disease. AJR Am J Roentogenol
1979;133:19–23.
15 Gupta AK, Anand NK, Lamba IMS. Ultrasoundevaluation of kidney dimensions in neonates.
Indian J Pediatr 1993;30:319–324.
16 Haller JO, Berdon WE, Friedman AP. Increased
renal cortical echogenicity: a normal findings inneonates and infants. Radiology 1982;142:173174.
17 H a n B K , B a b c o c k D S . S o n o g r a p h i cmeasurements and appearance of normal kidneys
in children. AJR Am J Roentgenol 1985;145:
611–616.
18 Harkness RD, Nightingale M. The extensibilityof the cervix uteri of the rat at different times ofpregnancy. J Physiol (Lond) 1962;160:214–220.
19 Harkness RD, Harkness MLR. Some mechanicalproperties of collagenous frameworks and theirfunctional significance. Biorheology 1963;1:
314–315.
20 Haugstvedt S, Lundberg J. Kidney size in normalchildren measured by sonography. Scand J Urol
Nephrol 1980;14:251–255
21 Hayden CK, Santa-Cruz FR, Amparo EG, Ben

older using modified ratios (Figs. 13 and 14).
More studies are needed to further evaluateechogenicity of the liver by computerizedhistogram sonography, especially in children
aged less than 1 year. This study was unable toshow a statistically significant difference inechogenicity of the liver in children with hepatic dysfunction and normal controls by using a
traditional Kr/L contrast ratio (Fig. 15).
We can conclude that i) the values of ratios,i.e., Kl/SP, Kr/SP and Kr/L started to increase
from d0, came to their peak at d2, and thereafter
decreased until 15 years of age; ii) the values inthe L/SP ratio increased (> 1) during the period
from birth through 6 months, and thereafter
decreased slightly to the level of 1 and remained
constant; iii) the significance of the modified
ratios in the early neonatal period remains
ambiguous; iv) there is a greater possibility ofincreased echogenicity in hepatic parenchyma
in children aged 1 year or older with high levelsof serum transaminases (increased SGPT and
SGOT); v) our new ratios may provide someadvantages over the generally accepted (traditional) Kr/L contrast ratio for determining
hepatic and renal echogenicity individually andmore accurately; and vi) echogenicitic assessment of renal and hepatic parenchyma by
naked-eye evaluation is not reliable.
Acknowledgments: We wish to express our thanks to
all the members in the Dept. of Pediatrics for theircooperation.

References
1 Benbridge AN, Chevalier RL, Kaiser DL. Increased renal cortical echogenicity in pediatricdisease. J Clin ultrasound 1986;14:595–600.
2 Blane CE, Jongeward RH, Silver TM. Sonographic features of the hepatocellular disease inneonates and infants. AJR Am J Roentogenol
1983;141:1313–1316.
3 Bondestam S, Alanen A, and Toikkanen S.
Correlation of liver echo intensity with cytology
and chemical measurements of fat, water andprotein content in live burbots (lota lota). Ultrasound Med Biol 1992;18:75–80.
4 Carson PL, Oughton TV. A modeled study for
diagnosis of small anechoic masses with ultrasound. Radiology 1977;122:765–771.

41

M. A. Samad et al.

30 Rosenfield AT, Siegel NJ. Renal parenchymal
disease: histopathologic-sonographic correlation. AJR Am J Roentogenol 1981;137:793–798.
31 Rosenfield AT, Taylor KJW, Jaffe CC. Clinicalapplications of ultrasound tissue characterization.
Radiol Clin North Am 1980;18:31–58.
32 Sandford NL, Pam Walsh P, Matis C, Baddeley
H, Powell LW. Is ultrasonography is useful in theassessment of diffuse parenchymal liver disease?
Gastroenterology 1985;89:186–191.
33 Sargent MA, Gupta SC. Sonographic measurement of relative renal volume: comparison withsintigraphic determination of relative renal
function. AJR Am J Roentogenol 1993;161:157–
160.
34 Scott JEF, Hunter EW, Lee REJ, Matthews JNS.
Ultrasound measurement of renal size in newborn
infants. Arch Dis Child 1990;65:361–364
35 Simpson WL. Connective tissues and cancer. In
Asboe-Hansen L, ed: Connective tissue in healthand disease. New York: Phylosophical Library,
1957:225–238.
36 Taylor KJW, Jacobson P, Jaffe CC. Lack ofacoustic shadow on scans of gallstones, a possible artifact. Radiology 1979;131:463–464.
37 Winkler P, Altrogge H. A comparison of renalsonography with clinical evaluation, laboratory
data and biopsy. Pediatr Radiol 1985;15:231–
237.
38 Wladimiroff JW, Sekeris A. Ultrasonic assessment of liver size in the newborn. J Clin Ultrasound 1976;5:316–320.

Brouhard, Swischuk LE, Ahrendt DK. Ultrasonographic evaluation of the renal parenchyma
in infancy and childhood. Radiology 1984;152:
413–417.
22 Henschke CI, Goldman H, Teele RL. Hyperechogenic liver in children: cause and sonographic appearance. AJR Am J Roentogenol
1982;138:841–846.
23 Holloway H, Jones TB, Robinson AE, Harpen
MD, Wiseman HJ. Sonographic determination ofrenal volumes in normal neonates. Pediatr Radiol
1983;13:212–214.
24 Hricak H, Slovis TL, Callen CW, Callen PW,
Romanski RN. Neonatal kidneys: sonographic
anatomic correlation. Radiology 1983;147:699–
702.
25 Jaffe CC, Taylor KJW. The clinical impact ofultrasonic beam focusing patterns. Radiology
1979;131:469–472.
26 Joseph AEA, Dewbury KC, McGuire PG. Ultrasound in the detection of chronic liver disease. Br
J Radiol 1979;52:184–188.
27 Kraus RA, Gaisie G, Young LW. Increased renalparenchymal echogenicity: causes in pediatricpatients. Radiographics 1990;10:1009–1018.
28 Kurtz AB, Rubin SR, Cooper HS, Nisenbaum HL,
Cole-Beuglet C, Medoff J, et al. Ultrasoundfindings in hepatitis. Radiology 1980;136:717–723.
29 Platt JF, Rubin JM, Bowerman RA, Marn CS.
The inability to detect kidney disease on the basisof echogenicity. AJR Am J Roentogenol 1988;
151:317–319.

(Received December 20, 1996, Accepted January 7, 1997)42