Joel
F. Platt,
Renal Role
MD
James
a
H. Ellis,
Transplant of Duplex
MD
#{149} Jonathan
transplant commonly
ENAL
sonography
(US)
struction
is an
ney,
Kidney,
stenosis
on obstruction,
transplantation,
81.455
81.12981,
81.12984
studies,
failure,
a
81.4552 81.4554
a
Kidney,
Ultrasound
a a
US
US,
however,
1991;
(1-5).
is ultra-
Urinary
important
MATERIALS
ob-
to produce
kidney.
Prior
of small groups of patients larger series have shown results
regarding
reports
as pant conflicting
Doppler
of
changes
in
association with transplant obstruction (12,14-16). The goal of our study was to proevaluate
the
role
Kidney, Doppler
planted
kidney.
Such
data
the
obditrans-
would
in-
crease the specificity of US for transplant obstruction by allowing identification of kidneys that, despite ex-
179:425-428
hibiting pyebocaliectasis, by obstructed.
are
not
caliectasis
of the
lecting tion,
system, and
clinically
pediatric this series;
tru-
From
the
Center
ben 23, 1990; 10. Address C
RSNA,
See
also
Department
Dr.
Ann
revision reprint
of Radiology, Arbor,
MI
requested requests
Box
0030,
48109-0030.
From
December to J.F.P.
10;
University the
1990
revision
of Michigan RSNA
received
scientific January
Hospitals, assembly. 4, 1991;
1500 Received accepted
E MediOcto-
cob-
dysfuncobstruction.
were included aged more than
in 18
years.
Real-time
examinations
transducer
(Acuson,
Calif)
renal
with
a 3.5-MHz
Mountain
or a 3.0-MHz
Technology and a pulsed
View,
transducer
(Advanced
Laboratories, Bothel!, Doppler evaluation
(arcuate
or interlobar)
Wash) of intra-
arteries
were
performed in each patient. Multiple Doppler signal tracings and a standard gray-scale examination of the kidney were recorded on film. The Doppler waveforms were made on the narrowest frequency
mange
possible
without
alias-
ing, which maximized the size of the Doppler spectrum and decreased the percentage of error in the measurement. In addition, the lowest possible wall filter for
each
US
machine
was
used
(50
Hz
for
the 3.0-MHz transducer and 125 Hz for the 3.5-MHz transducer). Doppler sample volume was 2-5 mm. From the hard copy, the RI ([peak systolic frequency shift - lowest diastolic frequency shift]/peak systolic frequency shift)
was
determined
sumements
from
performed
hand
with
mea-
a caliper.
as an average waveforms.
The
value
ob-
The presence or absence of obstruction was proved with interventional procedures
ous
(antegrade
pyelography,
nephrostomy,
in 18 patients (minimum,
interventional was made versing
percutane-
or retrograde
and clinical 6 months) in
studies)
follow-up 17 patients.
diagnosis of obstruction when no contrast material
the
ureter
could
be
identified
The
traflu-
oroscopically or on spot radiographs after careful but determined hand injection. The nonobstructed systems had free flow into
I
renal
transplant possible
patients all were
No
of contrast
cal
METHODS
transplanted
renal
RI was calculated tamed from 3-5
of duplex
Doppler US in distinguishing structed from the nonobstructed lated collecting system in the
Kid-
AND
Over a 2-year period, duplex Doppler US examinations were performed in 35 patients (22 men, 13 women) with pye!o-
transplant
is known
(transplanted)
81.12984
Radiology
dysfunction evaluated with
numerous false-positive results of examinations for obstruction (ie, dilatation without obstruction) (7,10-12). We recently reported that obstruction of native kidneys produces changes in the Doppler waveomm that result in an elevated resistive index (RI) (11,13). However, as the exact mechanism of this increased resistance is not definitely known, it is not clear whether similar changes can be expected in the denervated
studies,
(US),
PhD
complication that must be diagnosed early in the course of disease to meduce transplant damage (6-9). Iinfortunately, the clinical findings of an elevated creatinine level and reduced urinary output are nonspecific and mimic findings in many cases of nonobstructive transplant dysfunction. Gray-scale US is routinely used to search for dilatation of the renal transplant collecting system (1,7).
spectively terms:
MD,
Pyelocaliectasis: Doppler US in Evaluation’
To distinguish the obstructed from the nonobstructed dilated collecting system of transplanted kidneys without interventional diagnostic measures, the authors prospectively evaluated duplex Doppler analysis (determination of resistive index [RI]) in 35 renal transplant patients with pyelocaliectasis. Proof of the presence or absence of obstruction was obtained at interventional procedures in 18 patients and at clinical follow-up in 17. Thirteen kidneys were obstructed (mean RI, .81 ± .06), while 22 had nonobstructive dilatation (mean RI, .66 ± .07). The RI difference was statistically significant (P : .01). Of 21 kidneys with a normal RI, only two had obstruction. In both of these, the obstruction was associated with a significant pentransplant collection of fluid due to a ureteral leak. In the seven obstructed transplanted kidneys with follow-up, the mean RI was .82 ± .06 before nephrostomy and .67 ± .05 after nephrostomy. Obstruction was a common cause of an elevated RI (75). Other causes of transplant dysfunction can be associated with an elevated RI and nonobstructed dilatation. More important, a normal RI should strongly argue against obstruction unless a ureteral leak is also present. Index
M. Rubin,
the
material bladder.
(Whitaker
two systems
test)
through Pressure
were
because,
the ureter measurements
necessary
in only
in the remaining
January
1991
the
article
by Platt
et al (pp
419-423)
in this
issue.
Abbreviation:
RI
resistive
index.
425
systems
studied
in
an
antegrade
fashion,
obstruction was either essentially complete or clearly absent. The Whitaker test was considered abnormal if the renal pelvic pressure exceeded 18 cm of water at an infusion rate of 10 mLlmin and a significant partial obstruction was confirmed
fluoroscopically.
Seven
patients
with
obstructed
transun-
kidneys
derwent relief
percutaneous nephrostomy urinary obstruction underwent
of
follow-up 3-7
who
subsequently
planted
duplex
days
of
Doppler
study
obstruction
examinations as we have
significant in most kidneys
immediate patients with undergoing
a
within
relief.
mediate formed,
for
More
were previously
not
im-
pernoted
waveform obstructed nephrostomy
no
change native
(11,13). Sixteen of our patients percutaneous transplant the dysfunction of their
also underwent biopsy to assess transplanted kid-
neys.
correlated
These
results
were
the Doppler data and sence of obstruction. Statistical
means
the
analysis
of the
was
with
presence
or ab-
performed
two-tailed
by
Student
t test.
RESULTS RI values are compared with the presence or absence of obstruction and related factors in the Table for 35 patients
with
transplanted
.66
± .07)
(Fig
2). This
difference
patient,
the
RI was
normal
however, the patient had ed ureteral leak in addition partial obstruction. In seven of the patients structed
kidney,
perform
a follow-up
3-7
days
tion. mean
after
(.69);
.67
of the
study obstruc-
after
relief
of
(Fig
1). It is interest-
that
this
group
tion.
In this
would
clinical
be hand
struction
was
another
process
similar (transplant
a
elevating
that
can
was
kidney
associated
was
not
In addition mentioned
only
obstructhe ob-
with
great,
a sig-
averaging
to the above
three
who
ob-
RI when
produce
also present However,
diagnoses
in one,
one, two.
and
4%.
patients
underwent
in these
me-
acute
both
decrease in (in one pa-
patients
in three, acute and cyclosponine tubular
no specific
chronic chronic toxic-
necrosis
in
abnormality
in
DISCUSSION Urinary
it
whether the
proved to have of these patients,
nificant uneteral leak and resultant uninoma (Fig 3). As more than one vessel within each transplanted kidney was studied, we were able to assess whether RI varied significantly between different sites. In general, the amount of variation in RI within a particular
un-
obstruc-
situation,
changes was rejection).
Radiology
and
to know
patients had a dramatic the RI after nephrostomy 426
who
examinations with concomitant rejection
definite
sis in one. The other 21 transplant patients had an RI of
F. Platt,
Renal Role
MD
James
a
H. Ellis,
Transplant of Duplex
MD
#{149} Jonathan
transplant commonly
ENAL
sonography
(US)
struction
is an
ney,
Kidney,
stenosis
on obstruction,
transplantation,
81.455
81.12981,
81.12984
studies,
failure,
a
81.4552 81.4554
a
Kidney,
Ultrasound
a a
US
US,
however,
1991;
(1-5).
is ultra-
Urinary
important
MATERIALS
ob-
to produce
kidney.
Prior
of small groups of patients larger series have shown results
regarding
reports
as pant conflicting
Doppler
of
changes
in
association with transplant obstruction (12,14-16). The goal of our study was to proevaluate
the
role
Kidney, Doppler
planted
kidney.
Such
data
the
obditrans-
would
in-
crease the specificity of US for transplant obstruction by allowing identification of kidneys that, despite ex-
179:425-428
hibiting pyebocaliectasis, by obstructed.
are
not
caliectasis
of the
lecting tion,
system, and
clinically
pediatric this series;
tru-
From
the
Center
ben 23, 1990; 10. Address C
RSNA,
See
also
Department
Dr.
Ann
revision reprint
of Radiology, Arbor,
MI
requested requests
Box
0030,
48109-0030.
From
December to J.F.P.
10;
University the
1990
revision
of Michigan RSNA
received
scientific January
Hospitals, assembly. 4, 1991;
1500 Received accepted
E MediOcto-
cob-
dysfuncobstruction.
were included aged more than
in 18
years.
Real-time
examinations
transducer
(Acuson,
Calif)
renal
with
a 3.5-MHz
Mountain
or a 3.0-MHz
Technology and a pulsed
View,
transducer
(Advanced
Laboratories, Bothel!, Doppler evaluation
(arcuate
or interlobar)
Wash) of intra-
arteries
were
performed in each patient. Multiple Doppler signal tracings and a standard gray-scale examination of the kidney were recorded on film. The Doppler waveforms were made on the narrowest frequency
mange
possible
without
alias-
ing, which maximized the size of the Doppler spectrum and decreased the percentage of error in the measurement. In addition, the lowest possible wall filter for
each
US
machine
was
used
(50
Hz
for
the 3.0-MHz transducer and 125 Hz for the 3.5-MHz transducer). Doppler sample volume was 2-5 mm. From the hard copy, the RI ([peak systolic frequency shift - lowest diastolic frequency shift]/peak systolic frequency shift)
was
determined
sumements
from
performed
hand
with
mea-
a caliper.
as an average waveforms.
The
value
ob-
The presence or absence of obstruction was proved with interventional procedures
ous
(antegrade
pyelography,
nephrostomy,
in 18 patients (minimum,
interventional was made versing
percutane-
or retrograde
and clinical 6 months) in
studies)
follow-up 17 patients.
diagnosis of obstruction when no contrast material
the
ureter
could
be
identified
The
traflu-
oroscopically or on spot radiographs after careful but determined hand injection. The nonobstructed systems had free flow into
I
renal
transplant possible
patients all were
No
of contrast
cal
METHODS
transplanted
renal
RI was calculated tamed from 3-5
of duplex
Doppler US in distinguishing structed from the nonobstructed lated collecting system in the
Kid-
AND
Over a 2-year period, duplex Doppler US examinations were performed in 35 patients (22 men, 13 women) with pye!o-
transplant
is known
(transplanted)
81.12984
Radiology
dysfunction evaluated with
numerous false-positive results of examinations for obstruction (ie, dilatation without obstruction) (7,10-12). We recently reported that obstruction of native kidneys produces changes in the Doppler waveomm that result in an elevated resistive index (RI) (11,13). However, as the exact mechanism of this increased resistance is not definitely known, it is not clear whether similar changes can be expected in the denervated
studies,
(US),
PhD
complication that must be diagnosed early in the course of disease to meduce transplant damage (6-9). Iinfortunately, the clinical findings of an elevated creatinine level and reduced urinary output are nonspecific and mimic findings in many cases of nonobstructive transplant dysfunction. Gray-scale US is routinely used to search for dilatation of the renal transplant collecting system (1,7).
spectively terms:
MD,
Pyelocaliectasis: Doppler US in Evaluation’
To distinguish the obstructed from the nonobstructed dilated collecting system of transplanted kidneys without interventional diagnostic measures, the authors prospectively evaluated duplex Doppler analysis (determination of resistive index [RI]) in 35 renal transplant patients with pyelocaliectasis. Proof of the presence or absence of obstruction was obtained at interventional procedures in 18 patients and at clinical follow-up in 17. Thirteen kidneys were obstructed (mean RI, .81 ± .06), while 22 had nonobstructive dilatation (mean RI, .66 ± .07). The RI difference was statistically significant (P : .01). Of 21 kidneys with a normal RI, only two had obstruction. In both of these, the obstruction was associated with a significant pentransplant collection of fluid due to a ureteral leak. In the seven obstructed transplanted kidneys with follow-up, the mean RI was .82 ± .06 before nephrostomy and .67 ± .05 after nephrostomy. Obstruction was a common cause of an elevated RI (75). Other causes of transplant dysfunction can be associated with an elevated RI and nonobstructed dilatation. More important, a normal RI should strongly argue against obstruction unless a ureteral leak is also present. Index
M. Rubin,
the
material bladder.
(Whitaker
two systems
test)
through Pressure
were
because,
the ureter measurements
necessary
in only
in the remaining
January
1991
the
article
by Platt
et al (pp
419-423)
in this
issue.
Abbreviation:
RI
resistive
index.
425
systems
studied
in
an
antegrade
fashion,
obstruction was either essentially complete or clearly absent. The Whitaker test was considered abnormal if the renal pelvic pressure exceeded 18 cm of water at an infusion rate of 10 mLlmin and a significant partial obstruction was confirmed
fluoroscopically.
Seven
patients
with
obstructed
transun-
kidneys
derwent relief
percutaneous nephrostomy urinary obstruction underwent
of
follow-up 3-7
who
subsequently
planted
duplex
days
of
Doppler
study
obstruction
examinations as we have
significant in most kidneys
immediate patients with undergoing
a
within
relief.
mediate formed,
for
More
were previously
not
im-
pernoted
waveform obstructed nephrostomy
no
change native
(11,13). Sixteen of our patients percutaneous transplant the dysfunction of their
also underwent biopsy to assess transplanted kid-
neys.
correlated
These
results
were
the Doppler data and sence of obstruction. Statistical
means
the
analysis
of the
was
with
presence
or ab-
performed
two-tailed
by
Student
t test.
RESULTS RI values are compared with the presence or absence of obstruction and related factors in the Table for 35 patients
with
transplanted
.66
± .07)
(Fig
2). This
difference
patient,
the
RI was
normal
however, the patient had ed ureteral leak in addition partial obstruction. In seven of the patients structed
kidney,
perform
a follow-up
3-7
days
tion. mean
after
(.69);
.67
of the
study obstruc-
after
relief
of
(Fig
1). It is interest-
that
this
group
tion.
In this
would
clinical
be hand
struction
was
another
process
similar (transplant
a
elevating
that
can
was
kidney
associated
was
not
In addition mentioned
only
obstructhe ob-
with
great,
a sig-
averaging
to the above
three
who
ob-
RI when
produce
also present However,
diagnoses
in one,
one, two.
and
4%.
patients
underwent
in these
me-
acute
both
decrease in (in one pa-
patients
in three, acute and cyclosponine tubular
no specific
chronic chronic toxic-
necrosis
in
abnormality
in
DISCUSSION Urinary
it
whether the
proved to have of these patients,
nificant uneteral leak and resultant uninoma (Fig 3). As more than one vessel within each transplanted kidney was studied, we were able to assess whether RI varied significantly between different sites. In general, the amount of variation in RI within a particular
un-
obstruc-
situation,
changes was rejection).
Radiology
and
to know
patients had a dramatic the RI after nephrostomy 426
who
examinations with concomitant rejection
definite
sis in one. The other 21 transplant patients had an RI of
