Evaluation of Prospective Living Renal Donors for Laparoscopic Nephrectomy with Multisection CT: The Marriage of Minimally Invasive Imaging with Minimally Invasive Surgery1

Article (PDF Available)inRadiographics 21 Spec No(spec No):S223-36 · November 2001with13 Reads
DOI: 10.1148/radiographics.21.suppl_1.g01oc10s223 · Source: PubMed
Abstract
Laparoscopic technique for excision of a kidney from a living donor has advantages over conventional open surgery, but operative visibility and surgical exposure are limited. Preoperative multisection computed tomography (CT) can provide necessary anatomic information in a minimally invasive procedure. A three-phase examination is suggested: (a) imaging from the top of the kidneys to the pubic symphysis with a section width of 2.5 mm and no contrast medium, (b) scanning of the kidneys and upper pelvis during the arterial phase of enhancement with a section width of 1.0 mm, and (c) scanning of the kidneys and upper retroperitoneum during the nephrographic phase of enhancement with a section width of 1.0 mm. Emphasis in this article is placed on analysis of the venous anatomy because most radiologists are unfamiliar with the anatomic variations. Conventional radiography of the abdomen and pelvis is performed after CT to evaluate the collecting system and ureters and to provide a lower total radiation dose than if CT were used. Of several postprocessing techniques that may be used, the authors prefer maximum intensity projection for arterial evaluation and multiplanar reformatting for venous evaluation.
HELPING THE UROLOGIST S223
Evaluation of Prospective
Living Renal Donors for
Laparoscopic Nephrec-
tomy with Multisection
CT: The Marriage of
Minimally Invasive
Imaging with Minimally
Invasive Surgery1
LEARNING
OBJECTIVES
FOR TEST 5
After reading this
article and taking
the test, the reader
will be able to:
Describe the multi-
section CT scanning
protocol for renal
donor evaluation.
Evaluate potential
donors for contra-
indications to renal
donation.
Evaluate the renal
arterial and venous
anatomy.
Jonas Rydberg, MD Kenyon K. Kopecky, MD Mark Tann, MD
Scott A. Persohn, RT Stephen B. Leapman, MD Ronald S. Filo, MD
Arieh L. Shalhav, MD
Laparoscopic technique for excision of a kidney from a living donor has
advantages over conventional open surgery, but operative visibility and
surgical exposure are limited. Preoperative multisection computed to-
mography (CT) can provide necessary anatomic information in a mini-
mally invasive procedure. A three-phase examination is suggested:
(a) imaging from the top of the kidneys to the pubic symphysis with a
section width of 2.5 mm and no contrast medium, (b) scanning of the
kidneys and upper pelvis during the arterial phase of enhancement with
a section width of 1.0 mm, and (c) scanning of the kidneys and upper
retroperitoneum during the nephrographic phase of enhancement with
a section width of 1.0 mm. Emphasis in this article is placed on analysis
of the venous anatomy because most radiologists are unfamiliar with
the anatomic variations. Conventional radiography of the abdomen
and pelvis is performed after CT to evaluate the collecting system and
ureters and to provide a lower total radiation dose than if CT were
used. Of several postprocessing techniques that may be used, the au-
thors prefer maximum intensity projection for arterial evaluation and
multiplanar reformatting for venous evaluation.
Index terms: Kidney, CT, 81.12119 Kidney, transplantation, 81.455 Renal arteries, CT, 961.12919 Renal veins, CT, 966.12919
RadioGraphics 2001; 21:S223–S236
1From the Departments of Radiology (J.R., K.K.K., M.T., S.A.P.), Urology (A.L.S.), and Surgery (S.B.L., R.S.F.), Indiana University Hospital, 550
N University Blvd, Rm 0279, Indianapolis, IN 46202-5253. Recipient of a Certificate of Merit award for an education exhibit at the 2000 RSNA sci-
entific assembly. Received February 2, 2001; revision requested March 6 and received April 20; accepted April 25. Address correspondence to J.R.
(e-mail: jrydberg@iupui.edu).
©RSNA, 2001
CME FEATURE
See accompanying
test at http://
www.rsna.org
/education
/rg_cme.html
Introduction
Laparoscopic nephrectomy in living renal donors
was introduced in 1995 (1). Compared with open
nephrectomy, the laparoscopic procedure offers
advantages for the donor such as less time in the
hospital, less postoperative pain, fewer cosmetic
concerns, and less convalescence time (2– 4). Po-
tential living renal donors must undergo screen-
ing to determine their suitability for donation.
Imaging is part of this screening. By tradition,
living renal donors have undergone evaluation
with excretory urography and renal angiography.
Excretory urography depicted renal size, stone
disease, and pelvicaliceal anatomy, whereas an-
giography provided information about the renal
arterial anatomy. Both methods failed to depict
small stones, subtle masses, and detailed informa-
tion about venous abnormalities. Several studies
have shown that evaluation of potential renal do-
nors with excretory urography and renal angiog-
raphy can be replaced with helical computed to-
mography (CT) (5–11). CT also allows definition
of the renal venous anatomy, including the renal
vein, adrenal vein, gonadal vein, and lumbar veins
(7,8). The left kidney is preferred for laparoscopic
surgery. Most surgeons will accept donors with
one or two accessory renal arteries. Surgeons
need complete information about the venous
anatomy because venous bleeding is a potentially
serious complication of laparoscopic surgery that
sometimes requires the conversion of a laparo-
scopic procedure to an open one.
Multisection CT, with acquisition of four sec-
tions at a time, was introduced in 1998. Multisec-
tion CT examinations can be performed with
thinner section thickness and shorter acquisition
time than can single-section CT. The preopera-
tive evaluation of renal donors with multisection
CT can provide a more detailed and sensitive
analysis of the renal vasculature and pathologic
conditions than before.
Exclusion criteria for laparoscopic donor ne-
phrectomy include unilateral agenesis, renal ecto-
pia, horseshoe kidney, urolithiasis, multiple renal
arteries, renal arterial disease, complex venous
anatomy (circumaortic or retroaortic left renal
vein), renal neoplasm, hydronephrosis, cortical
atrophy, medullary sponge kidney disease, renal
papillary necrosis, retroperitoneal varices, and
other abnormalities.
This article presents a technique for evaluating
potential renal donors with multisection CT and
displays clinical examples. Emphasis is placed on
the analysis of the venous anatomy because most
radiologists are unfamiliar with the anatomic
variations. In addition, the veins are small and
travel in many directions, providing challenges
that require specialized techniques and worksta-
tion tools to reveal their courses. The presented
methods of evaluation of the vascular anatomy
represent 2 years of experience with a quad-sec-
tion CT scanner. No formal scientific study has,
to our knowledge, proved which scanning tech-
nique is optimal.
Technique Consider-
ations for Multisection CT
The parameters for the multisection CT protocol
are dependent on the speed of the scanner, the
section thickness options, the number of scanning
phases (scanning timing relative to the adminis-
tration of contrast medium), and the anatomic
coverage of each scan. The phases that can be
considered are precontrast, arterial, venous,
nephrographic, and delayed. Precontrast scans
are used to locate the kidneys, detect urolithiasis,
and provide baseline attenuation measurements
of renal masses. The optimal timing for the con-
trast-enhanced phases is dependent on the vol-
ume of contrast medium, the rate of its adminis-
tration, and the subject’s cardiac output. The de-
lay time refers to the difference between the start
of contrast medium injection and the start of
scanning. Arterial-phase scanning, performed to
evaluate the arterial anatomy, is begun after a de-
lay time of 15 seconds. The high rate of injection
(5 mL/sec) necessitates the use of a shorter delay
time for the arterial phase. Venous-phase scan-
ning, performed to evaluate the venous anatomy,
is begun after a delay of 40 –50 seconds. The
nephrographic phase refers to the time during
which the renal cortex and medulla are uniformly
enhanced and contrast medium has not yet en-
tered the renal calices and pelvis. This phase is
optimal for evaluation of the renal parenchyma
and detection of focal masses that arise in the cor-
tex or medulla. The phase is best visualized with
a delay time of 75–100 seconds. The delayed
phase, used to evaluate the collecting system, oc-
curs with a delay time of 5 minutes or more. As
an alternative, the collecting system and ureters
may be evaluated with conventional radiography
after CT.
S224 October 2001 RG fVolume 21 Special Issue
Although a five-phase CT examination may be
possible with a multisection CT scanner, there
are reasons to restrict the number of phases. First
and most important, we must limit the radiation
dose to the subjects, who are generally healthy,
young adults. Second, even multisection scanners
have limitations, and there are trade-offs to be
made among spatial resolution of the images (in
all three planes), image noise, and scanning
speed. Because of limitations in anode heat ca-
pacity, it is impossible to perform a five-phase,
1-mm-section-width examination and produce
images with acceptable noise levels.
Rationale and Procedures
for Three-Phase Renal Evaluation
As a compromise, to limit radiation dose, we use
a three-phase CT examination followed with con-
ventional radiography. Dedicated venous-phase
scanning is not performed because the renal veins
become enhanced quickly and are usually seen on
arterial-phase scans. The gonadal and lumbar
veins become enhanced more slowly and are seen
well on nephrographic-phase scans. A section
width of 1 mm is used for both the arterial- and
nephrographic-phase examinations because ac-
cessory renal arteries and lumbar veins can be
small and easily missed when thicker sections are
used. Delayed-phase CT scans are not obtained
because conventional radiography provides the
same information at a lower radiation dose. Con-
ventional radiography is required to depict ure-
teral anomalies and diseases such as medullary
sponge kidney disease and papillary necrosis that
cannot be diagnosed with CT. The total radiation
dose for three-phase CT is about 7.7 rad, sub-
stantially less than that with the combination of
angiography and excretory urography. The fol-
lowing imaging strategy is based on 2 years of ex-
perience with a quad-section CT scanner.
Phase 1: Precontrast
Scanning is performed from the top of the kid-
neys to the pubic symphysis without the use of
contrast medium. The technical factors for the
Mx8000 scanner (Marconi Medical Systems,
Cleveland, Ohio) are shown in Table 1.
Table 1
Technique for Quad-Section CT before Laparoscopic Nephrectomy in Living Renal Donors
Scanning Phase
Precontrast Arterial Nephrographic
Coverage Top of kidneys
to pubic
symphysis
Top of kidneys
to 2 cm above
iliac crest
Top of kidneys
to 2 cm above
iliac crest
Data acquisition
Kilovolt peak 120 120 120
Milliampere seconds 150 170 200
Focal spot Large Large Large
Nominal section width (mm) 2.5 1.0 1.0
Sections per rotation 4 4 4
Rotation time (sec) 0.5 0.5 0.5
Table speed (mm/sec) 20 8 8
Pitch 1.0 1.0 1.0
Scanning time (sec) 15 20 20
Coverage (cm) 30 16 16
Data reconstruction
Reconstruction algorithm 360° 360° 360°
Reconstruction increment (mm) 1.2 0.5 0.5
Reconstruction field of view (cm) 27 27 27
Filter Standard body Standard body Standard body
Edge enhancement None None None
Postprocessing . . . Maximum intensity
projection, volume
rendering
Multiplanar
reformatting
RG fVolume 21 Special Issue Rydberg et al S225
Phase 2: Arterial
An 18-gauge angiographic catheter is placed into
a basilic vein or the brachial vein (with ultrasono-
graphic guidance) at the elbow, and saline solu-
tion is administered. Nonionic contrast medium
containing 300 mg of iodine per milliliter at a
dose of 2 mL per kilogram of body weight (limit,
190 mL) is injected at 5 mL/sec. The delay time
from the start of injection to the start of scanning
is 15 seconds. A test bolus is not used. Scanning
is performed from the top of the kidneys to 2 cm
below the top of the iliac crest. The technical fac-
tors are shown in Table 1. In large subjects, a
larger section width (2.5 mm) may be required to
maintain acceptable levels of image noise. If a
polar artery emerges from the lower part of the
aorta or from the common iliac artery, the part of
the artery near its origin will not be seen but the
part near the kidney will be depicted. In the rare
occurrence of this variant, repeated imaging may
be necessary to fully evaluate the path of the
vessel.
Phase 3: Nephrographic
The delay time from the start of injection to the
start of scanning is 75 seconds. Scanning is per-
formed in a fashion identical to that during the
arterial phase.
Conventional Radiography
Conventional radiography of the abdomen and
pelvis is performed 5 minutes after the CT exami-
nation (10 minutes after injection) with the sub-
ject in the supine position and the use of 65 kVp,
narrow-latitude film, rare earth screens, and
phototiming.
Postprocessing
All renal donor images are routinely sent to a
workstation (MxView; Marconi Medical Sys-
tems). The postprocessing evaluation may in-
clude the use of the following techniques: mul-
tiplanar reformatting, maximum intensity pro-
jection, shaded surface display, and volume
rendering (12). The postprocessing cannot be
reduced to just one technique, since the various
postprocessing methods have different advantages
and shortcomings. The maximum intensity pro-
jection technique, for example, is excellent in
bringing out high-attenuation, high-contrast,
well-defined structures such as arteries, while
multiplanar reformatting is the preferred tech-
nique for analysis of small, less well opacified
veins.
“Image Load”
A complete evaluation usually contains more than
800 source images (precontrast phase, 200; ar-
terial phase, 300; and venous phase, 300) and
additional postprocessed images. Our data sets
for the arterial and nephrographic phases are iso-
tropic (1-mm spatial resolution in all planes),
which provides tremendous flexibility for ana-
tomic display. However, this “image load” may
become a psychologic and logistic burden if it is
not dealt with correctly (14). First, the bandwidth
of the local network must be adequate to quickly
transfer the large image volume from the scanner
to the workstation. Second, the workstation
should have at least 1 Gbyte of memory, and it
should handle several large stacks of images si-
multaneously. The image load on the radiologic
technologists, radiologists, and surgeons can be
eased by not printing the source images. A limited
number of pertinent images of the arterial and
venous anatomy and any pathologic conditions
can be created for the surgeon.
Measurements
Measurements of the vascular structures are per-
formed on “curved-plane” multiplanar reformat-
ted images. These measurements help the sur-
geons find the arteries and veins that we detected
preoperatively. Most surgeons require at least 2
cm of renal artery before hilar branching to en-
sure adequate control and anastomosis.
Figure 1. Exclusion from surgery due to renal stone
disease in a potential renal donor. Maximum inten-
sity projection CT scan shows two left renal stones
(arrows).
S226 October 2001 RG fVolume 21 Special Issue
Evaluation of Potential Renal Donors
Renal Stone Disease
When excretory urography and angiography were
used to evaluate potential donors, no subject with
urolithiasis was allowed to donate a kidney. With
the excellent contrast resolution of CT, we have
found that the prevalence of urolithiasis is much
higher than previously reported, and we detect
stones in many subjects who have never experi-
enced symptoms or at least never had the diagno-
sis established. Because of the apparent increased
prevalence of asymptomatic urolithiasis, some
transplantation centers allow some asymptomatic,
otherwise healthy subjects with urolithiasis to do-
nate provided they have a low stone burden. One
policy regarding renal stone disease permits dona-
tion with the provision that the subject is asymp-
tomatic, is more than 40 years old, and has only
one stone smaller than 8 mm in diameter or no
more than three stones, all unilateral and each
smaller than 3 mm in diameter (Fig 1). However,
more restrictive policies exist for cases in which
any depicted stone becomes an absolute contra-
indication to renal donation.
Evaluation of Arteries and Veins
In 70% of cases, single renal arteries exist bilater-
ally. In 30%, multiple renal arteries are present.
Anatomic variants include supplementary arter-
ies, polar arteries, and extrahilar branching. The
number of arteries, their sizes, and the locations
of their origins on the aorta determine whether
the kidney is suitable for donation. The lengths of
the arteries from their origins to the first bifurca-
tion are measured. The arterial evaluations can be
performed with maximum intensity projection
(Fig 2), shaded surface display (Fig 3), or volume
Figure 2. Maximum intensity projection CT
scans show accessory renal arterial variants: hilar
artery to the left kidney (arrow in a), early branching
to the right kidney (arrowheads in b) and polar ar-
tery to the left kidney (arrow in b), and multiple po-
lar arteries to both kidneys (arrows in c).
Figure 3. Shaded surface display CT scan shows
multiple accessory renal arteries: hilar (arrowheads)
and polar (open arrow). Main arteries are marked with
solid arrows.
RG fVolume 21 Special Issue Rydberg et al S227
rendering (Fig 4). Arterial diseases such as renal
arterial aneurysm (Fig 5) or renal arterial stenosis
due to atherosclerosis or fibromuscular dysplasia
can be detected.
In 85% of people, there is a single right renal
vein. In 86% of people, there is a single left
preaortic renal branch often combined with sev-
eral extrarenal branches. The location and num-
ber of gonadal, adrenal, and lumbar veins must
be delineated (Fig 6). Venous variants include
multiple veins, right-sided gonadal and adrenal
veins entering into the renal vein, and left retro-
aortic, circumaortic, and partially duplicated
Figure 4. Volume rendering software allows di-
rect interactive adjustment of size, angulation, and
thickness of the tissue volume (slab) under evalua-
tion. The images show what happens to two 1-mm-
wide polar arteries (arrows in a) when the slab is
moved. When the slab is more ventral (a), one
branch is partially out of view (arrowhead in a), but
when the slab is moved dorsally (b), the more dor-
sally projecting polar artery comes into view (ar-
rowhead in b). The more dorsal location of the
slab in bis indicated by the visibility of a vertebra.
(c) When the slab is tilted, the small arteries are
seen as separate vessels (arrow) and can thus be
evaluated individually.
Figure 5. Exclusion of a potential renal donor
from donor surgery due to a right renal arterial
aneurysm (arrow). Curved coronal reformatted
image demonstrates an aneurysm that is throm-
botic and partially calcified.
S228 October 2001 RG fVolume 21 Special Issue
Figure 6. Analysis of drainage into the renal veins. (a) Coronal reformatted CT image shows
gonadal vein (arrow) entering the left renal vein from below. (b) Oblique coronal reformatted im-
age shows the left adrenal vein (solid arrow) draining into the renal vein. The inferior mesenteric
artery (open arrow) and adrenal gland (arrowheads) are also visible. (c) Axial reformatted image
shows a left lumbar vein (arrow) entering dorsally into the renal vein.
RG fVolume 21 Special Issue Rydberg et al S229
S230 October 2001 RG fVolume 21 Special Issue
veins (Figs 7–9). The relationships among the
renal, lumbar, and gonadal veins may be varied.
Because laparoscopic surgery is performed with a
more limited view than is open surgery, the sur-
geon needs to be forewarned about any anoma-
lies. This forewarning reduces the risk of acciden-
tal venous injuries and bleeding. The renal veins
and tributaries that drain into them must be
shown. Any veins that drain into the proximal 2
Figure 9. Circumaortic left renal vein shown with both
shaded surface display and reformatting. The stair-step arti-
facts in the images result from the use of 3-mm instead of
1-mm collimation. Aaorta, Ggonadal vein, Vvena
cava. (a) Shaded surface display image depicts the anomaly
(arrows) on one image. (b, c) Due to the oblique courses of
the renal vein branches, several reformatted images are
needed to show the anteroaortic renal branch (open arrows in
c) and the retroaortic renal vein (solid arrows in b). In this
case, the anomaly could not be shown with the volume ren-
dering technique. At our institution, a potential donor with a
retroaortic or circumaortic vein may donate the kidney; how-
ever, the surgery must be open rather than laparoscopic.
ŠFigures 7, 8. (7a) Volume-rendered image shows a duplicated renal vein (arrows) and a large gonadal vein (arrow-
heads). (7b) Two oblique lines on the reference image denote the thickness and angulation of the volume evaluated
in a.(7c) Coronal reformatted image shows the split renal vein (arrows) and gonadal vein (arrowheads) in fine detail.
(7d) Photograph obtained during surgery shows the split of the renal vein (S) close to the renal hilum and the merger
(M) medially. The entry of the wide gonadal vein (G) is also seen. The duplication of the renal vein was overlooked
during the initial evaluation in which only axial images were reviewed. (8) Split left renal vein not detected prior to
surgery. The split was discovered during laparoscopic nephrectomy. In retrospect, the split renal vein could be de-
tected on the axial source images (arrows in aand b). The duplication could also be brought out with volume render-
ing (c). The techniques of maximum intensity projection, shaded surface display, and multiplanar reformatting did
not adequately show the anomaly.
RG fVolume 21 Special Issue Rydberg et al S231
cm of the gonadal vein must also be reported be-
cause they may be included in the dissection
(Fig 10).
The larger veins can be evaluated with the vol-
ume rendering technique (Fig 11); however, to
find all smaller veins, we believe that the multipla-
nar reformatting technique is best and should em-
ploy axial, coronal, sagittal, and oblique planes
(Figs 12, 13). Retroperitoneal varices can be de-
tected with this technique (Fig 14).
Figure 10. Accessory veins draining into the proximal 2 cm of the gonadal vein. (a) Oblique coronal
reformatted CT scan shows two small tributaries to the gonadal vein (G): one 5 mm below (arrowheads)
and one 10 mm below (arrows) the renal vein. (b, c) The inflows of the two small tributaries into the
gonadal vein are shown on axial CT scans obtained 5 mm (arrowhead in b) and 10 mm (arrow in c) be-
low the renal vein. (d) Volume-rendered image shows the gonadal vein (G) but not the small contribu-
tory veins. The renal vein is split (S).
Figures 11, 12. (11) Volume rendering versus multiplanar oblique and curved reformatting in the detection of
pathologic conditions and understanding of the three-dimensional relationships. Coronal (a) and axial (b) reformat-
ted images show the relationships among the large renal pelvis (P), renal veins, and gonadal vein (arrow in aand c)as
well as a coronal volume-rendered image does (c).(12) Accessory left renal vein and large left gonadal vein at reformat-
ting. (a) Coronal reformatted image shows the accessory renal vein (curved arrow) merging into the gonadal vein (straight
solid arrow) just beneath the point where the gonadal vein merges with the main renal vein (open arrow). (b) Photograph
obtained during surgery helps confirm the findings at CT. Gonadal vein with surgical clip (short straight arrow), main re-
nal vein (long straight arrow), and accessory renal vein (curved arrow) are evident. (c) Photograph obtained during surgery
shows gonadal vein (straight arrow), lifted with a surgical instrument, immediately beneath the point where the accessory
renal vein entered the gonadal vein. At this point, a 2-mm-wide vein was found (curved arrow). (d) Axial CT image ob-
tained during the nephrographic phase shows that this small vein (arrow) could be depicted in retrospect.
S232 October 2001 RG fVolume 21 Special Issue
RG fVolume 21 Special Issue Rydberg et al S233
Figure 13. Value of thin-collimation multisection CT and multiplanar reformatting in the delineation
of veins that merge into the renal vein. Arenal artery, Ad adrenal vein, Ao aorta, Ggonadal
vein, IMV inferior mesenteric vein, Llumbar vein, Nlymph node, SMA superior mesenteric
artery, Vrenal vein. (a, b) Axial (a) and sagittal (b) reformatted images best display the lumbar vein.
(c) Oblique coronal reformatted image best depicts the merging renal veins. (d) Oblique sagittal refor-
matted image shows the paired gonadal veins.
Figure 14. Exclusion of a potential
renal donor from surgery due to retro-
peritoneal varices. Coronal reformatted
image shows the varices (arrows).
S234 October 2001 RG fVolume 21 Special Issue
Evaluation of Renal Parenchyma
The renal parenchyma is best evaluated at the
nephrographic phase, which is used to detect dis-
eases such as polycystic disease and renal cell car-
cinoma (13). Small isolated renal cysts are usually
not contraindications to surgery.
Evaluation of the
Collecting System and Ureters
Medullary sponge kidney disease and papillary
necrosis are contraindications to renal donation,
and these diseases cannot be detected with CT
(although complications from these diseases can
sometimes be detected). The best way to screen
for these diseases is with conventional radiogra-
phy performed 10 minutes after the CT examina-
tion. A CT scout view does not have adequate
quality to substitute for a conventional radio-
graph. Conventional radiography allows depiction
of duplication anomalies of the collecting system
and ureters.
Clinical Experience
During the period January–October 2000, renal
donor CT evaluation was performed in 52 sub-
jects. Of the 52 subjects, 30 donated kidneys: 24
via laparoscopic surgery and six via open surgery.
Surgery was not performed in 22 subjects. In 12
of the nondonors, CT showed pathologic pro-
cesses or anatomic variations that excluded them
from donation (renal cystic disease, n4; vascu-
lar variation, n1; renal stones, n6; and blad-
der calcifications, n1). In 10 subjects, the rea-
sons for exclusion were unrelated to renal anat-
omy or pathologic conditions (improved renal
status of recipient, n1; donor hypertension,
n1; donor history of cancer, n1; recipient
health problems, n1; and cross match incapa-
bility, n6). Of the 52 subjects, only 14 had
completely normal findings at scanning. Twenty-
seven had abnormal vascular anatomy (Table 2),
12 had abnormalities in their kidneys, and 12 had
other findings such as liver or splenic lesions. In
five subjects, the only abnormal finding was in the
kidneys, and six had abnormal kidney findings
and vascular variants.
Discovered during surgery were 12 vascular
variants that had not been reported by the radi-
ologist. Nine variants were venous (two left lum-
bar and two left adrenal veins, small posterior
branches of the left renal vein, two left lumbar
veins, one large left lumbar vein [n2], partially
duplicated left renal vein, and multiple small ret-
roperitoneal veins [n3]). Three variants were
arterial (early left renal arterial bifurcation, supe-
rior left accessory renal artery, severe angulation
of the left renal artery). One unexpected finding
required that surgery be converted from laparo-
scopic to open. All of these variants, except one,
were visible in retrospect on the CT images (ei-
ther on axial source images or on reformatted im-
ages). Most errors were made early in our experi-
ence. All nine donor kidneys were successfully
transplanted.
Discussion
In the past, when living renal donors underwent
open surgical techniques, the radiologist needed
to provide only information about the arterial
anatomy and any pathologic processes. Now, the
advent of laparoscopic nephrectomy has created a
new challenge for radiologists: definition of the
Table 2
Vascular Variants in Potential Living Renal
Donors
Variant Type
No. of
Cases
Arterial
Accessory right renal arteries 9
Accessory left renal arteries 8
Triple right renal arteries 5
Prehilar branching left renal artery 2
Prehilar branching right renal arteries 2
Triple left renal arteries 1
Subtotal 27
Venous
Prehilar branching left renal vein 4
Accessory left renal veins 2
Retroperitoneal tributary vein 2
Large veins mimicking circumaortic left
renal veins 2
Accessory right renal vein 1
Circumaortic left renal veins 1
Large gonadal vein 1
Left vein communicating with two
gonadal veins 1
Multiple small perinephric veins 1
Multiple small vertebral veins 1
Retroperitoneal varices 1
Subtotal 17
Total 44
Note.—Vascular variants were found in 27 of 52
potential donors.
RG fVolume 21 Special Issue Rydberg et al S235
venous anatomy. Multisection CT allows defini-
tion of that anatomy and more. Multisection CT
followed by conventional radiography provides a
complete evaluation with much more information
than was previously provided with excretory urog-
raphy and angiography. It is much more sensitive
in the detection of urolithiasis and diseases of the
renal parenchyma. The CT examination is also
less invasive and less costly.
There is a learning curve for radiologists, and
perception errors are common during analysis of
the venous system, at least early in one’s experi-
ence. Vascular variants are common (44 variants
in 27 of 52 patients). Our errors prompted us to
change the imaging technique to enhance the
quality of the venous interpretation. Earlier,
2.5-mm section thickness was used. Now we try
to use 1.0 mm for the nephrographic phase. Ear-
lier, we also relied heavily on analysis of the axial
images during evaluation of the veins. According
to our experience, a “volume approach” is more
beneficial. With the 1-mm scanning technique,
isotropic viewing is possible. We believe that ves-
sels passing in planes oblique to the axial plane
are best evaluated with reformatted images. We
had hoped that volume rendering would be the
answer to all questions; however, this has not
been the case. We have found it necessary to learn
the anatomy as viewed in coronal, sagittal, and
oblique planes, and for that the multiplanar refor-
matting technique is essential.
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S236 October 2001 RG fVolume 21 Special Issue
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    • "A single topogram is not always sufficient to assess the collecting system, but in most cases it is. In fact, most published authors agree with the use of a delayed topogram with the goal of reducing radiation or even conventional radiography [3, 6–8]. Although it is assumed that taking the patient to the x-ray facility would be more complicated and time consuming, a topogram in the modern CT scanners has a high-quality image. "
    [Show abstract] [Hide abstract] ABSTRACT: BACKGROUND: Renal vasculature is known for having a broad spectrum of variants, which have been classically reported by anatomists. METHODS: The distribution and morphology of these variations can be explained by considering the embryology of the renal vessels. With the recent outburst of imaging techniques, it has been the radiologist's turn to take the baton, recognising and describing unconventional renal vascular patterns. RESULTS: Knowledge of these patterns has gained significance since the advent of the era of transplantation. For almost 60 years cadaveric donation has been the main source of kidneys suitable for transplantation. Living kidney donation demonstrates many advantages and stands out as the best alternative for organ procurement to meet the increasing demand. Since the dawn of laparoscopic nephrectomy as the technique of choice for organ procurement in living kidney donors, MDCT plays a key role as a noninvasive preoperative planning method for anatomic evaluation. As the field of view at laparoscopic surgery is limited, it is essential to meticulously assess the origin, number, division and course of arteries and veins. CONCLUSION: Awareness of the different anatomical variants allows the radiologist to enlighten the surgeon in order to avoid compromising the safety of the surgical procedure that could lead to significant complications. TEACHING POINTS: • Renal vasculature has many variants, which can be explained by considering the embryology of kidneys. • Living kidney donation demonstrates many advantages over cadaveric donation. • Angio CT evaluation of living kidney donors is a multiple phase study. • A detailed report describing the variants, their distribution and morphology will help surgeons.
    Full-text · Article · Jan 2013
    • "The prevalence of a supernumerary renal vein has been reported to be in the range from 9-28% (2, 6, 14, 15). Forty-eight kidneys (15.6%) had multiple renal veins in our study, which is concurrent with previous studies. "
    [Show abstract] [Hide abstract] ABSTRACT: To determine the accuracy of the use of multi-detector row CT (MDCT) to predict vascular anatomy in living kidney donors and to reveal the prevalence of vascular variations in a Korean population. A total of 153 living kidney donors that had undergone preoperative CT and nephrectomy, either with open or laparoscopic surgery, were selected retrospectively. The initial CT results were compared with the surgical findings and repeated review sessions of CT scans were performed to determine the causes of mismatches in discordant cases. The accuracy of CT angiography was 95% to predict the number of renal vessels. Four arteries and two veins were missed during the initial CT interpretation due to perception errors (for two arteries and two veins) and technical limitations (two arteries). The prevalence of multiple renal arteries and veins, early branching of a renal artery and late confluence of a renal vein were 31%, 5%, 12%, 17%, respectively. The circumaortic renal vein and the bilateral inferior vena cava were found in two cases each (1.3%). One case (0.7%) each of a retroaortic renal vein and a supradiaphragmatic originated renal artery were found. MDCT provides a reliable method to evaluate the vascular anatomy and variations of living kidney donors.
    Full-text · Article · Aug 2008
    • "Cette dernière étude a également employé un enregistrement numérique vidéo 3-D qui a probablement contribué à ces résultats impressionnants . Tandis que les nouvelles technologies logicielles permettent ce type d'imagerie tridimensionnelle, des études précédentes ont présenté de bons résultats en termes de sécurité obtenus avec l'angiographie tomodensitométrique sans capacité 3-D [51, 52] . Le McGill University Health Center a récemment montré qu'une angiographie tomodensitométrique bidimensionnelle permettait une planification chirurgicale adéquate lorsqu'elle était associée à une dissection laparoscopique et à une coopération complète avec l'équipe de transplantation [53] . "
    [Show abstract] [Hide abstract] ABSTRACT: Kidney transplantation is the therapeutic option of choice for patients with end-stage renal disease. With the advent of safer harvesting techniques and immunosuppression, both donor and recipient outcomes have markedly improved in recent years. Kidney donation from living donors remains the single most important factor responsible for improving patient and graft survival. The laparoscopic donor nephrectomy has revolutionized renal transplantation, allowing expansion of the donor pool by diminishing surgical morbidity while maintaining equivalent recipient outcome. This technique is now becoming the gold-standard harvesting procedure in transplant centres worldwide, despite its technical challenge and ongoing procedural maturation, especially early in the learning curve. Previous contraindications to laparoscopic donor nephrectomy are no longer absolute. In the following analysis, the procedural aspects of the laparoscopic donor nephrectomy are detailed including pre-operative assessment, operative technique and a review of the current literature delineating aspects of both donor and recipient morbidity and mortality compared with open harvesting techniques.
    Article · Aug 2007
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