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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5802_Библиотеки_им_академика_М_И_Перельмана.pdf
Urinary tract
46
Anteroposterior dimension: Measured from the sagittal image measured perpendicular to the long axis.
Width: Measured from a transverse image taken from the lateral margin of the kidney through the renal hilum.
Renal cortical thickness is >1 cm over the pyramids, but that measurement often decreases with age.
Renal length decreases with age, almost entirely as a result of parenchymal reduction. Height and age, but not sex, are determinate of
renal size. There is no difference in kidney length measurements in the
supine oblique and prone positions.
Normal mean values in cm (± SD)*
Length Anteroposterior Width
Right kidney Oblique 10.65 ± 1.4 3.95 ± 0.8 4.92 ± 0.6
Prone 10.74 ± 1.4 4.17 ± 0.5 5.05 ± 0.8
Left kidney Oblique 10.13 ± 1.2 3.58 ± 0.9 5.30 ± 0.7
Prone 11.10 ± 1.2 4.14 ± 0.8 5.30 ± 0.8
Size of the kidney with age in cm (decades)^
rd
3
th
4
th
5
th
6
7th 8
th
th
9
Right 11.3 11.2 11.2 11.0 10.7 9.9 9.6
Left 11.5 11.5 11.4 11.3 10.9 10.2 9.8
FURTHER READING
*Brandt TD, Nieman HL, Dragowski MJ, Bulawa W, Claykamp G.
Ultrasound assessment of normal renal dimension. J Ultrasound
Med. 1982; 1:49–52.
Emamian SA, Nielsen MB, Pedersen JF, Ytte L. Kidney dimensions
at sonography: Correlation with age, sex, and habitus in 665
adult volunteers. AJR Am J Roentgenol. 1993;160:83-86.
^Miletic D, Fuckar Z, Sustic A, Mozetic V, Stimac D, Zauhar G.
Sonographic measurement of absolute and relative renal length in
adults. J Clin Ultrasound. 1998; 26:185–189.
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Evaluation of acute renal obstruction
with intrarenal Doppler
PREPARATION
None.
POSITION
Supine.
TRANSDUCER
2.0–6.0 MHz curvilinear transducer.
METHOD
Doppler signals are obtained from arcuate arteries at the corticomedullary junction or interlobar arteries along the border of medullary
pyramids. The Doppler waveforms should be made on the lowest
pulse repetition frequency without aliasing to maximize the size of the
Doppler spectrum. The Resistance Index (RI) is calculated from the
formula:
Peak Systolic Velocity – End Diastolic Velocity
RI =
APPEARANCE
The normal spectral Doppler waveforms in the renal arcuate arteries
are those of a low-resistance end-organ, with a broad systolic peak and
an elevated end-diastolic velocity.
MEASUREMENTS
Elevation of the RI occurs after just 6 hours of clinical obstruction.
Mean RI in normal kidneys is 0.60 ± 0.04.
Mean RI of obstructed kidneys is 0.77 ± 0.07.
If there is pyelosinus extravasation on the urographic imaging or the
duration of obstruction is less than 6 hours, the RI may not be elevated.
Peak Systolic Velocity
Evaluation of acute renal obstruction with intrarenal Doppler
Doppler signals are
obtained from the
arcuate arteries at the
corticomedullary junction of
the interlobar arteries along
the border of the medullary
pyramids.
FURTHER READING
Platt JF, Rubin JM, Ellis JH. Acute renal obstruction: Evaluation
with intrarenal duplex Doppler and conventional US. Radiology.
1993; 186:685–688.
Rodgers PM, Bates JA, Irving HC. Intrarenal Doppler studies in
normal and acutely obstructed kidneys. Br J Radiol. 1992;
65:207–212.
49
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50
Renal circulation and renal artery
PREPARATION
None.
POSITION
Supine, lateral decubitus.
TRANSDUCER
Low-frequency curvilinear (typically 1.0–5.0 MHz). A low-frequency
phased array (1.0–4.0 MHz) may be useful to investigate the renal
artery.
METHOD
Intrarenal arteries
The kidneys are imaged from the ank with the patient in a supine or
lateral decubitus position. Coronal views usually give a clear longitudinal image of the kidneys, although there is anatomical variation and
oblique views may be better. The liver and spleen can be used as acoustic windows. For intrarenal arteries, a higher color frequency (typically
3 MHz) gives greater sensitivity to segmental and interlobar arteries.
For intrarenal arteries, angle correction is usually not required because
the resistance index (RI) is the main measurement taken.
Renal arteries
The proximal renal arteries can be obtained from an anterior transverse view. This usually offers a clear B-mode image of the renal artery
origins. Color Doppler frequency should be low (2 MHz). The Doppler
angle correction should be ≤ 60°.
The renal arteries may also be imaged from the patient’s ank in a
coronal or oblique view, although transverse views may be useful. This
view often allows images of the entire renal artery to segmental artery
level. Doppler angle corrections are usually low because the renal
arteries are closely aligned to the beam direction. Velocities measured
in this view may be lower than angle-corrected measurements from an
anterior approach.
Velocities should be measured from origin to segmental artery level
and the highest velocity obtained. Atherosclerotic renal artery stenosis
is usually at the ostium and proximal renal artery; bromuscular dysplasia stenosis is usually in the mid/distal renal artery.
APPEARANCE
Appearances as described above.
Intrarenal ow waveform from
a healthy kidney showing low
resistance ow with a RI of 0.61.
Renal circulation and renal artery
51
Increased renovascular resistance results in a
loss of diastolic ow measured as an RI of 0.8.
Slow heart rates result in a
longer diastolic phase with
a reduction in end diastolic
ow. This increases RI. With
a faster heart rate, the RI
would be less than 0.72
measured here.
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High velocities in the renal artery origin indicates a tight stenosis. There is no beam/ow
angle correction made, so peak systolic velocity (PSV) is at least 342 cm/s. Problems when
measuring renal artery velocities include movement through the sample volume and the
need for high pulse repetition frequency with an additional sample volume and reduced
signal/noise in the sonogram.
MEASUREMENTS
Intrarenal arteries
Resistance Index (RI) =
Peak Systolic Velocity – End Diastolic Velocity
Peak Systolic Velocity
The RI in healthy kidneys ranges from 0.55–0.7, increasing with age.
There is variation within a kidney; ow waveforms in healthy kidneys
become less pulsatile from the renal artery through to the interlobar
and distal artery level. RI should be measured at the interlobar artery
level for consistency.
Resistance indices of ≥ 0.8 are associated with reduced renal blood
ow and increased renovascular resistance in a range of parenchymal disorders. Resistance indices of 1.0 are associated with severely
impaired renal function.
Care should be taken when reporting RIs in patients with low heart
rates. The long diastolic component results in reduced end diastolic
ows and elevated RIs.
Renal arteries
The normal PSV in adult renal arteries is from 60–100 cm/s; it is
slightly higher in children. Peak velocities of ≥ 180 cm/s are indicative
of stenosis; velocities ≥ 200 cm/s have been shown to have good correlation with pressure drops of 20 mmHg with higher velocities indica-
Renal circulation and renal artery
tive of more severe disease. Renal artery–aortic ratio (RAR) of > 3.0
is indicative of stenosis, with higher values more specic of stenosis.
Intrarenal ow waveform changes have been proposed as indicative
of stenosis. Most commonly used is an acceleration time of > 70 ms.
Several studies have shown this to have high specicity but low sensitivity to stenosis.
FURTHER READING
House MK, Dowling RJ, King P, Gibson RN. Using Doppler
sonography to reveal renal artery stenosis: An evaluation of
optimal imaging parameters. AJR Am J Roentgenol. 1999;
173:761–765.
Kawarda O, Yokoi Y, Takemoto K, Morioka N, Nakata S, Shiotani
S. The performance of renal duplex ultrasonography for the
detection of hemodynamically signicant renal artery stenosis.
Cath Cardiovasc Intervent. 2006; 68: 311–318.
Keogan MT, Kliewer MA, Hertzberg BS, DeLong DM, Tupler
RH, Carroll BA. Renal resistive indexes: Variability in Doppler
US measurement in a healthy population. Radiology. 1996;
199:165–169.
Staub D, Canevascini R, Huegli RW, Aschwanden M, Thalhammer
C, Imfeld S, Singer E, Jacob AL, Jaeger KA. Best duplexsonographic criteria for the assessment of renal artery stenosis—
correlation with intra-arterial pressure gradient. Ultraschall
Med. 2007; 28:45–51.
Tublin ME, Bude RO, Platt JF. The resistive index in renal Doppler
sonography: Where do we stand? AJR Am J Roentgenol. 2003;
180:885–892.
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Retroperitoneal lymph nodes
PREPARATION
None.
POSITION
Supine.
TRANSDUCER
2.0–6.0 MHz curvilinear transducer
METHOD
Longitudinal and transverse sections are used to image the aorta and
the inferior vena cava. Lymph nodes can sometimes be identied
around these structures. In normal subjects and with adequate visualization, normal-sized lymph nodes are most likely to be detected, in
descending order of frequency, in the aorto-caval, left para-aortic, and
peripancreatic regions.
APPEARANCE
Normal lymph nodes are attened, low-reective structures with an
eccentric highly reective area representing the fatty hilum.
MEASUREMENT
Lymph nodes > 1 cm short axis are considered to be abnormally
enlarged.
FURTHER READING
Dietrich CF, Zeuzem S, Caspary WF, Wehrmann T. Ultrasound
lymph node imaging in the abdomen and retroperitoneum of
health probands. Ultraschall in Medizin. 1998; 19:265–269.
Koenigsberg M, Hoffman JC, Schnur J. Sonographic evaluation of
the retroperitoneum. Sem Ultrasound. 1982; 3:79–96.
Marchal G, Oyen R, Verschakelen J, Gelin J, Baert AL, Stessens RC.
Sonographic appearance of normal lymph nodes. J Ultrasound
Med. 1985; 4:417–419.
Retroperitoneal lymph nodes
An axial section at the level of the aorta and celiac axia, demonstrating multiple enlarged
lymph nodes.
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