773
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Color Doppler Sonography of Ureteral Jets in Normal Volunteers: Importance of the Relative Specific Bladder
Scott William
M. Baker1
D. Middleton
Gravity
of Urine
in the Ureter
and
OBJECTIVE. Sonographic visualization of ureteral jets is a well-recognized phenomenon. In vitro studies have indicated that detection of fluid flow similar to ureteral jets depends on differences in density between the moving and the stationary fluid. This study was undertaken to determine if differences in density between ureteral urine and urine in the bladder could make a significant impact on the sonographic detectability of ureteral jets in vivo SUBJECTS AND METHODS. Ten healthy volunteers were vigorously hydrated after an overnight fast. An initial color Doppler sonographic examination of ureteral jets was
performed
before voiding
(while concentrated
urine that had accumulated
overnight
was
still in the bladder). A second examination was performed after two cycles of voiding and refilling the bladder (to ensure that dilute urine produced by the hydration was in the bladder). RESULTS. In all subjects, normal ureteral jets were readily identified on the initial examination. The difference in the estimated specific gravity between bladder urine and ureteral urine during the initial examination ranged from 0.002 to 0.016 (mean, 0008). This was a statistically significant difference (p < .05). On the second examination, ureteral jets were not detected from either ureter in any subject. The difference in the estimated specific gravity of bladder urine and ureteral urine during the second examination ranged from 0.000 to 0002 (mean, 0.001). This was not a statistically significant difference (p > .05). There was no statistically significant difference in the diuresis rates throughout the course of the examinations. These ranged from 300 to 1218 mI/hr. CONCLUSION. These in vivo results support the hypothesis that detection of ureteral jets depends on density differences between ureteral and bladder urine. This is importent clinically, because normal ureteral jets may be undetectable, despite adequate hydration and high rates of diuresis, if the patient is allowed to completely void and refill the bladder before the examination. AJR
Received
February
6, 1992; accepted
after re-
vision April 16, 1992. Both
authors:
Mallinckrodt
Institute
of Radiol-
ogy, Washington University School of Medicine, S. Kingshighway Blvd., St. Louis, MO 63110. dress reprint requests to W. D. Middleton.
0361-803X/92/1 594-0773 C American Roentgen Ray Society
510 Ad-
159:773-775,
October
1992
The detection of ureteral jets as echogenic streams arising from the ureteral orifices and entering the bladder has been well described on gray-scale sonography [1]. Recently, color Doppler sonography has been used to image ureteral jets [2]. Burge et al. [2] have shown that color Doppler analysis of ureteral jets can provide a means of documenting renal obstruction. This study, conducted in a group of patients with ureteral stones demonstrated that it is possible to document readily detectable ureteral jets on the unobstructed side and an absence of ureteral jets on the obstructed side. Detection of ureteral jets on the asymptomatic side is critical in order to confirm that nondetection on the symptomatic side is not related to poor overall diuresis or improper technical factors. Therefore, if this technique is to have success, it is important to maximize the likelihood of detecting normal ureteral jets. Previous in vitro studies have indicated that sonographic detection of fluid jets is dependent on differences in density between the fluid exiting the orifice and the fluid residing within the reservoir [3, 4]. This study was undertaken to determine if
BAKER
774
this dependence on density differences could potentially the results of ureteral jet analysis in healthy volunteers.
AND
MIDDLETON
affect
AJR:159,
October
1992
Results
The results obtained for each participant are shown in Table 1 In all iO subjects, normal ureteraljets were readily identified on the initial examination (Fig. iA). The difference in specific gravity between bladder urine and ureteral urine during the initial study (estimated as the difference between specimens 1 and 2) ranged from 0.002 to 0.01 6 (average, 0.0075). This difference was statistically significant (p < .05). On the second study, ureteral jets were not detected in any subject (Fig. i B). The differences in the specific gravity of bladder urine and ureteral urine (estimated as the difference between specimens 2 and 3) ranged from 0.000 to 0.002 (average, 0.0005). This difference was not statistically signifcant (p > .05). The average initial diuresis rate was 762 mI/hr (range, 390i3i4 ml/hr). The average second diuresis rate was 684 ml/ hr (range, 300-i i04 ml/hr). The average final diuresis rate was 756 mI/hr (range, 480-i 21 8 mI/hr). The difference in the diuresis rates was not statistically significant (p > .05). .
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Subjects
and
Methods
Color Doppler healthy
sonography
men (age
examination,
range,
of ureteral
27-38
the subjects
years
jets was performed old).
were instructed
in 10 of the
On the morning
not to completely
void after
awakening. Partial voiding was allowed if necessary. They were vigorously hydrated orally with 2 I of water during a 1 .0- to 1 .5-hr interval. After hydration but before complete voiding, the first color
Doppler
study of ureteral
jets was performed
(while concentrated
urine that had accumulated overnight was still in the bladder). Immediately after this first study, the subjects were allowed to void completely, and a sample was saved for measurement of specific gravity (specific gravity 1 in Table 1). The specific gravity of each of the three voided specimens was determined by using a Reichert refractometer (Baxter Diagnostics, Earth City, MO). The bladder was allowed to refill and after approximately 15-20 mm, the participants
voided again; a sample was saved for specific gravity (specific gravity
2 in Table 1), and the diuresis
rate was documented.
Diuresis
rate
was calculated by measuring voided urine volume and dividing by the time required to produce that volume. The bladder was allowed to refill and after
1 5-20
was performed the bladder).
more
minutes,
a second
(while dilute urine produced Immediately
after the second
color
Doppler
by the hydration study,
Discussion
study
A number of potential mechanisms have been proposed as being responsible for the formation of sonographically detectable ureteral jets. Among these are microbubbles or particulate matter in the urine, turbulence or cavitation at the ureteral orifice, temperature differences between ureteral and bladder urine, and density differences between ureteral and bladder urine [i , 4-6]. Price et al. [4] provided convincing evidence that the latter mechanism is primarily responsible for the detection of fluid jets in vitro. In this in vivo study, we attempted to manipulate the density of ureteral and bladder urine in order to determine if density differences would affect detection of ureteral jets despite high rates of diuresis. Subjects were vigorously hydrated in the morning but were instructed not to completely empty the bladder. Partial voiding was allowed if necessary. This ensured a situation in which bladder urine would have a high density (because it contained some concentrated urine that had accumulated overnight) while ureteral urine would have a low density (because it contained dilute urine produced after the early morning hydration). Color Doppler sonographic
was in
the subjects
voided
a third time, and again a sample was saved for specific gravity (specific gravity 3) and a diuresis rate was calculated. The bladder was allowed to refill one last time, and after 15-20 mm, the subjects voided and a final diuresis rate was calculated. All color
Doppler
sonographic
examinations
were
performed
with
a commercially available unit (Ultramark-9, Advanced Technology Laboratories, Bothell, WA) with a 3-MHz phased-array transducer. A low pulse-repetition frequency (1500 Hz), moderate receiver gain, and moderate output were used to optimize visualization. The wall filter was set at 50-i
00 Hz. Flow toward
a red color. The bladder was examined level of the trigone
were scanned
(to view
the transducer
was assigned
in the transverse
both jets simultaneously).
for 5 mm, and the examination
subsequent review. The Friedman test was used to determine
plane at the
All participants
was videotaped
if statistically
for
significant
differences existed between the calculated diuresis rates. The Wilcoxon signed-rank test was used to determine if statistically significant differences existed between the first and second and between the second
TABLE
and third
1: Individual
specific
gravities.
Urine Specific
Gravities
and Diuresis
Rates Subject
Number
Characteristic
Average
1
2
3
4
5
6
7
8
9
10
1
1.007
1.008
1.010
1.012
1.012
1.004
1.009
1.004
1.014
1.018
1.0098
2
1.003
1.003
1.002
1.002
1.004
1.002
1.002
1.001
1.002
1.002
1.0023
1.003 0.004 0.000
1.001 0.005 0.002
1.001 0.008 0.001
1.002 0.010 0.000
1.004 0.008 0.000
1.002 0.002 0.000
1.001 0.007 0.001
1.001 0.003 0.000
1.002 0.012 0.000
1.001 0.016 0.001
1.0018 0.0075 0.0005
Specific
Gravity
3 1-2 2-3 Diuresis (ml/hr) 1
858
1314
390
600
624
600
798
1122
600
720
762
2
1104
876
486
300
456
504
720
822
564
1020
684
3
1218
750
498
666
480
570
882
1128
720
630
756
AJR:159,
COLOR
October 1992
DOPPLER
SONOGRAPHY
OF URETERAL
775
JETS
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Fig. 1.-Color Doppler sonographic appearance of ureteral jets in subject 7. A, Transverse image of the bladder taken during initial examination shows bilateral, easily detectable ureteral jets crossing in midline. Multiple other jets were detected bilaterally during the remainder of this 5-mm examination. B, Similar image taken during second examination shows no detectable ureteral jets. No jet
was detected on either side during the entire 5mm examination.
analysis
under these conditions
confirmed
easily detectable
bilaterally symmetric ureteral jets in all subjects. Then the patients were allowed to completely void, refill, and completely void one more time in order to wash out any of the concentrated urine from the bladder. The bladder was then refilled a
second
time, with dilute urine exiting
the ureters to ensure
a
situation in which density of ureteral and bladder urine would be similar. Color Doppler sonographic examinations per-
formed jets
under the latter circumstances
in any
subject
despite
were similar throughout contention
the study.
of Price et al. [4] that
reason that ureteral
failed to show ureteral
documented
diuresis
These results density
jets are detectable
rates
that
confirm
the
differences
are the
sonographically.
In our study, one participant (subject 6) had detectable jets at an estimated density difference of 0.002 while another participant (subject 2) had no detectable jets at a similar density difference. This apparent overlap was probably due to the fact that exact density measurements of ureteral and bladder urine could not be obtained noninvasively. While the values we used were the best possible estimates, a slight underestimation of the density of bladder urine during the initial examination was unavoidable because the first specimen was constantly being diluted by nonconcentrated ureteral urine. Therefore, the actual density differences of ureteral and
bladder urine during the first examination
were slightly greater
than
of these
what
suspect is required
was
estimated.
that a density to detect
was the minimum
On the basis
difference ureteral
density
results,
we
of slightly greater than 0.002
jets
difference
in vivo.
Interestingly,
required
to visualize
0.002
fluid
jets in vitro [4]. Our results underscore an important technical consideration that must be taken into account when performing ureteral jet analysis in a true clinical setting. All previous reports on this subject have emphasized the need for good hydration of the patient before the examination [i, 2, 4]. This is important
because it increases the frequency of ureteral jets and thus facilitates comparison of the normal and abnormal side and shortens the amount of time needed for examination. However, if the well-hydrated patient is allowed to completely void and then refill his bladder before ureteral jet analysis by color Doppler examination, then detection of ureteral jets will be extremely difficult, if not impossible. Therefore, patients should not be allowed to completely empty their bladder after hydration. If the patient becomes uncomfortable because of bladder distension, partial voiding is suggested, since this will maintain some concentrated urine in the bladder and thus ensure at least some difference in the density between bladder and ureteral urine. Alternatively, if the patient is unable to partially void and complete voiding is unavoidable, then placement of a Foley catheter and filling of the bladder with a saline solution should be considered in order to optimize ureteral jet detection. The latter procedure also may be necessary in patients with defects in renal concentrating ability.
REFERENCES 1 . Dubbins
PA, Kurtz AB, Darby J, Goldberg
echographic
appearance
1981;140:513-515 2. Burge HJ, Middleton healthy
subjects
of
urine
entering
WD, McClennan
and in patients
BB. Uretenc jet effect: the the
bladder.
Radiology
BL, Hildebolt CF. Ureteral jets in comparison
with unilateral ureteral calculi: Radiology 1991;180:437-440
with color Doppler ultrasound. 3. Kremer H, Dobrinski W, Mikyska M, Baumgartner M, Zollner N. Litrasonic in vivo and in vitro studios on the nature of the ureteral jet phenomenon. Radiology
1982;142: 175-1 77
4. Price CI, Adler R5, Rubin JM. ljtrasound explanation
detection ofdifferencos
of the
uretenc jet phenomenon applications. Invest Radiol 1989;24:
in density:
and implications 876-883
for
new
ultrasound 5. Meltzer RS, Tickner EG, Sahines TP, Popp RL. The source of ultrasound contrast
effect.
J Clin Ultrasound
1980;8:
6. Kremkau FW, Gramiak A, Carstensen detection
of cavitation
at catheter
121 -1 27
EL, Shah PM, Kramer DH. tJtrasonic
tips. AJR 1970;1 10:177-1
83
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Color Doppler Sonography of Ureteral Jets in Normal Volunteers: Importance of the Relative Specific Bladder
Scott William
M. Baker1
D. Middleton
Gravity
of Urine
in the Ureter
and
OBJECTIVE. Sonographic visualization of ureteral jets is a well-recognized phenomenon. In vitro studies have indicated that detection of fluid flow similar to ureteral jets depends on differences in density between the moving and the stationary fluid. This study was undertaken to determine if differences in density between ureteral urine and urine in the bladder could make a significant impact on the sonographic detectability of ureteral jets in vivo SUBJECTS AND METHODS. Ten healthy volunteers were vigorously hydrated after an overnight fast. An initial color Doppler sonographic examination of ureteral jets was
performed
before voiding
(while concentrated
urine that had accumulated
overnight
was
still in the bladder). A second examination was performed after two cycles of voiding and refilling the bladder (to ensure that dilute urine produced by the hydration was in the bladder). RESULTS. In all subjects, normal ureteral jets were readily identified on the initial examination. The difference in the estimated specific gravity between bladder urine and ureteral urine during the initial examination ranged from 0.002 to 0.016 (mean, 0008). This was a statistically significant difference (p < .05). On the second examination, ureteral jets were not detected from either ureter in any subject. The difference in the estimated specific gravity of bladder urine and ureteral urine during the second examination ranged from 0.000 to 0002 (mean, 0.001). This was not a statistically significant difference (p > .05). There was no statistically significant difference in the diuresis rates throughout the course of the examinations. These ranged from 300 to 1218 mI/hr. CONCLUSION. These in vivo results support the hypothesis that detection of ureteral jets depends on density differences between ureteral and bladder urine. This is importent clinically, because normal ureteral jets may be undetectable, despite adequate hydration and high rates of diuresis, if the patient is allowed to completely void and refill the bladder before the examination. AJR
Received
February
6, 1992; accepted
after re-
vision April 16, 1992. Both
authors:
Mallinckrodt
Institute
of Radiol-
ogy, Washington University School of Medicine, S. Kingshighway Blvd., St. Louis, MO 63110. dress reprint requests to W. D. Middleton.
0361-803X/92/1 594-0773 C American Roentgen Ray Society
510 Ad-
159:773-775,
October
1992
The detection of ureteral jets as echogenic streams arising from the ureteral orifices and entering the bladder has been well described on gray-scale sonography [1]. Recently, color Doppler sonography has been used to image ureteral jets [2]. Burge et al. [2] have shown that color Doppler analysis of ureteral jets can provide a means of documenting renal obstruction. This study, conducted in a group of patients with ureteral stones demonstrated that it is possible to document readily detectable ureteral jets on the unobstructed side and an absence of ureteral jets on the obstructed side. Detection of ureteral jets on the asymptomatic side is critical in order to confirm that nondetection on the symptomatic side is not related to poor overall diuresis or improper technical factors. Therefore, if this technique is to have success, it is important to maximize the likelihood of detecting normal ureteral jets. Previous in vitro studies have indicated that sonographic detection of fluid jets is dependent on differences in density between the fluid exiting the orifice and the fluid residing within the reservoir [3, 4]. This study was undertaken to determine if
BAKER
774
this dependence on density differences could potentially the results of ureteral jet analysis in healthy volunteers.
AND
MIDDLETON
affect
AJR:159,
October
1992
Results
The results obtained for each participant are shown in Table 1 In all iO subjects, normal ureteraljets were readily identified on the initial examination (Fig. iA). The difference in specific gravity between bladder urine and ureteral urine during the initial study (estimated as the difference between specimens 1 and 2) ranged from 0.002 to 0.01 6 (average, 0.0075). This difference was statistically significant (p < .05). On the second study, ureteral jets were not detected in any subject (Fig. i B). The differences in the specific gravity of bladder urine and ureteral urine (estimated as the difference between specimens 2 and 3) ranged from 0.000 to 0.002 (average, 0.0005). This difference was not statistically signifcant (p > .05). The average initial diuresis rate was 762 mI/hr (range, 390i3i4 ml/hr). The average second diuresis rate was 684 ml/ hr (range, 300-i i04 ml/hr). The average final diuresis rate was 756 mI/hr (range, 480-i 21 8 mI/hr). The difference in the diuresis rates was not statistically significant (p > .05). .
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Subjects
and
Methods
Color Doppler healthy
sonography
men (age
examination,
range,
of ureteral
27-38
the subjects
years
jets was performed old).
were instructed
in 10 of the
On the morning
not to completely
void after
awakening. Partial voiding was allowed if necessary. They were vigorously hydrated orally with 2 I of water during a 1 .0- to 1 .5-hr interval. After hydration but before complete voiding, the first color
Doppler
study of ureteral
jets was performed
(while concentrated
urine that had accumulated overnight was still in the bladder). Immediately after this first study, the subjects were allowed to void completely, and a sample was saved for measurement of specific gravity (specific gravity 1 in Table 1). The specific gravity of each of the three voided specimens was determined by using a Reichert refractometer (Baxter Diagnostics, Earth City, MO). The bladder was allowed to refill and after approximately 15-20 mm, the participants
voided again; a sample was saved for specific gravity (specific gravity
2 in Table 1), and the diuresis
rate was documented.
Diuresis
rate
was calculated by measuring voided urine volume and dividing by the time required to produce that volume. The bladder was allowed to refill and after
1 5-20
was performed the bladder).
more
minutes,
a second
(while dilute urine produced Immediately
after the second
color
Doppler
by the hydration study,
Discussion
study
A number of potential mechanisms have been proposed as being responsible for the formation of sonographically detectable ureteral jets. Among these are microbubbles or particulate matter in the urine, turbulence or cavitation at the ureteral orifice, temperature differences between ureteral and bladder urine, and density differences between ureteral and bladder urine [i , 4-6]. Price et al. [4] provided convincing evidence that the latter mechanism is primarily responsible for the detection of fluid jets in vitro. In this in vivo study, we attempted to manipulate the density of ureteral and bladder urine in order to determine if density differences would affect detection of ureteral jets despite high rates of diuresis. Subjects were vigorously hydrated in the morning but were instructed not to completely empty the bladder. Partial voiding was allowed if necessary. This ensured a situation in which bladder urine would have a high density (because it contained some concentrated urine that had accumulated overnight) while ureteral urine would have a low density (because it contained dilute urine produced after the early morning hydration). Color Doppler sonographic
was in
the subjects
voided
a third time, and again a sample was saved for specific gravity (specific gravity 3) and a diuresis rate was calculated. The bladder was allowed to refill one last time, and after 15-20 mm, the subjects voided and a final diuresis rate was calculated. All color
Doppler
sonographic
examinations
were
performed
with
a commercially available unit (Ultramark-9, Advanced Technology Laboratories, Bothell, WA) with a 3-MHz phased-array transducer. A low pulse-repetition frequency (1500 Hz), moderate receiver gain, and moderate output were used to optimize visualization. The wall filter was set at 50-i
00 Hz. Flow toward
a red color. The bladder was examined level of the trigone
were scanned
(to view
the transducer
was assigned
in the transverse
both jets simultaneously).
for 5 mm, and the examination
subsequent review. The Friedman test was used to determine
plane at the
All participants
was videotaped
if statistically
for
significant
differences existed between the calculated diuresis rates. The Wilcoxon signed-rank test was used to determine if statistically significant differences existed between the first and second and between the second
TABLE
and third
1: Individual
specific
gravities.
Urine Specific
Gravities
and Diuresis
Rates Subject
Number
Characteristic
Average
1
2
3
4
5
6
7
8
9
10
1
1.007
1.008
1.010
1.012
1.012
1.004
1.009
1.004
1.014
1.018
1.0098
2
1.003
1.003
1.002
1.002
1.004
1.002
1.002
1.001
1.002
1.002
1.0023
1.003 0.004 0.000
1.001 0.005 0.002
1.001 0.008 0.001
1.002 0.010 0.000
1.004 0.008 0.000
1.002 0.002 0.000
1.001 0.007 0.001
1.001 0.003 0.000
1.002 0.012 0.000
1.001 0.016 0.001
1.0018 0.0075 0.0005
Specific
Gravity
3 1-2 2-3 Diuresis (ml/hr) 1
858
1314
390
600
624
600
798
1122
600
720
762
2
1104
876
486
300
456
504
720
822
564
1020
684
3
1218
750
498
666
480
570
882
1128
720
630
756
AJR:159,
COLOR
October 1992
DOPPLER
SONOGRAPHY
OF URETERAL
775
JETS
Downloaded from www.ajronline.org by Fisher Library on 03/15/15 from IP address 129.78.139.28. Copyright ARRS. For personal use only; all rights reserved
Fig. 1.-Color Doppler sonographic appearance of ureteral jets in subject 7. A, Transverse image of the bladder taken during initial examination shows bilateral, easily detectable ureteral jets crossing in midline. Multiple other jets were detected bilaterally during the remainder of this 5-mm examination. B, Similar image taken during second examination shows no detectable ureteral jets. No jet
was detected on either side during the entire 5mm examination.
analysis
under these conditions
confirmed
easily detectable
bilaterally symmetric ureteral jets in all subjects. Then the patients were allowed to completely void, refill, and completely void one more time in order to wash out any of the concentrated urine from the bladder. The bladder was then refilled a
second
time, with dilute urine exiting
the ureters to ensure
a
situation in which density of ureteral and bladder urine would be similar. Color Doppler sonographic examinations per-
formed jets
under the latter circumstances
in any
subject
despite
were similar throughout contention
the study.
of Price et al. [4] that
reason that ureteral
failed to show ureteral
documented
diuresis
These results density
jets are detectable
rates
that
confirm
the
differences
are the
sonographically.
In our study, one participant (subject 6) had detectable jets at an estimated density difference of 0.002 while another participant (subject 2) had no detectable jets at a similar density difference. This apparent overlap was probably due to the fact that exact density measurements of ureteral and bladder urine could not be obtained noninvasively. While the values we used were the best possible estimates, a slight underestimation of the density of bladder urine during the initial examination was unavoidable because the first specimen was constantly being diluted by nonconcentrated ureteral urine. Therefore, the actual density differences of ureteral and
bladder urine during the first examination
were slightly greater
than
of these
what
suspect is required
was
estimated.
that a density to detect
was the minimum
On the basis
difference ureteral
density
results,
we
of slightly greater than 0.002
jets
difference
in vivo.
Interestingly,
required
to visualize
0.002
fluid
jets in vitro [4]. Our results underscore an important technical consideration that must be taken into account when performing ureteral jet analysis in a true clinical setting. All previous reports on this subject have emphasized the need for good hydration of the patient before the examination [i, 2, 4]. This is important
because it increases the frequency of ureteral jets and thus facilitates comparison of the normal and abnormal side and shortens the amount of time needed for examination. However, if the well-hydrated patient is allowed to completely void and then refill his bladder before ureteral jet analysis by color Doppler examination, then detection of ureteral jets will be extremely difficult, if not impossible. Therefore, patients should not be allowed to completely empty their bladder after hydration. If the patient becomes uncomfortable because of bladder distension, partial voiding is suggested, since this will maintain some concentrated urine in the bladder and thus ensure at least some difference in the density between bladder and ureteral urine. Alternatively, if the patient is unable to partially void and complete voiding is unavoidable, then placement of a Foley catheter and filling of the bladder with a saline solution should be considered in order to optimize ureteral jet detection. The latter procedure also may be necessary in patients with defects in renal concentrating ability.
REFERENCES 1 . Dubbins
PA, Kurtz AB, Darby J, Goldberg
echographic
appearance
1981;140:513-515 2. Burge HJ, Middleton healthy
subjects
of
urine
entering
WD, McClennan
and in patients
BB. Uretenc jet effect: the the
bladder.
Radiology
BL, Hildebolt CF. Ureteral jets in comparison
with unilateral ureteral calculi: Radiology 1991;180:437-440
with color Doppler ultrasound. 3. Kremer H, Dobrinski W, Mikyska M, Baumgartner M, Zollner N. Litrasonic in vivo and in vitro studios on the nature of the ureteral jet phenomenon. Radiology
1982;142: 175-1 77
4. Price CI, Adler R5, Rubin JM. ljtrasound explanation
detection ofdifferencos
of the
uretenc jet phenomenon applications. Invest Radiol 1989;24:
in density:
and implications 876-883
for
new
ultrasound 5. Meltzer RS, Tickner EG, Sahines TP, Popp RL. The source of ultrasound contrast
effect.
J Clin Ultrasound
1980;8:
6. Kremkau FW, Gramiak A, Carstensen detection
of cavitation
at catheter
121 -1 27
EL, Shah PM, Kramer DH. tJtrasonic
tips. AJR 1970;1 10:177-1
83
