Hiromu
Mori,
MD
Frank
P. McGrath,
#{149}
The Gastrocolic CT Evaluation’ Dilatation colic
or occlusion
trunk
portal
(GT)
venous
logic
may
of the gastropatho-
To evaluate
and
the
surgical-pathologic
were
A normal was
studied
GT (2.6-4.7-mm
identifiable
group
for comparison.
in 48%
in CT scans
diameter) of the
obtained
control
with
mm-thick sections and in 90% scans obtained with 5-mm-thick
tions. tients
The CT was with isolated
clusion
and
dilated splenic
in five
patients
10-
of CT sec-
in five pavein ocwith
occlusion
or stenosis of the portalmesenteric vein confluence (P-SMVC) above the level of the CT entry into the superior mesenteric vein. The CT was obliterated in eight patients and was associated with P-SMVC occlusion. Findings at surgery confirmed tumor extension into superior
the root in three pancreas. however,
of the transverse mesocolon patients with cancer of the Abnormal findings at CT, do not enable differentia-
tion between benign pancreatic diseases.
and malignant
Index terms: Pancreas, CT, 70.1211 creas, neoplasms, 77.321 #{149} Pancreatitis, Veins, CT, 959.1211 #{149} Veins, gastrocolic, 959.92 #{149} Veins, mesenteric, 959.92 Radiology
1992;
182:871-877
Pan77.291
#{149}
E. Malone,
Its
and
MB
Giles
#{149}
W. Stevenson,
MB
Tributaries:
HE pancreatico-duodenal
along nor-
records of 21 patients with cancer of the pancreas and 15 patients with chronic pancreatitis were reviewed retrospectively. The CT examinations of 30 patients with metastatic disease of the liver and no known pancreatic disease
T
to a
mal and abnormal appearances of the GT and its tributaries at computed tomography (CT), the CT scans, angiograms,
#{149} Dermot
Trunk
be a clue
or pancreatic
condition.
MB
and gastrocolic the anterior
faces of the tle attention
head has
veins trunk (GT) nun and posterior sur-
of the pancreas. Litbeen paid to their
cross-sectional imaging dilatation or occlusion a pathologic condition veins or the pancreas. the posterior superior duodenal ondary
(1-4). Their may be clues in the portal Dilatation of pancreatico-
vein (PSPDV) may to occlusive changes
to
be secin the
other pancreatico-duodenal veins and/or the portal-superior mesenteric venous confluence (P-SMVC) The GT comprises veins of the
Figure (4).
transverse mesocobon and one of the pancreatico-duodenal veins. The CT nuns transversely in front of the infenor portion of the head of the pancreas and drains into the right lateral wall of the superior mesenteric vein (SMV) (5-8). Although its location is usually constant, one author has reported the CT to be anatomically bocated below the head of the pancreas (9). Evaluation of the portal vein and SMV with CT has a robe in staging of pancreatic carcinoma (10). An assessment with CT of the CT and its tnbutaries may lead to a more precise understanding of the extent of a pathologic condition arising from the pancreas. The purposes of this study were to define normal CT anatomy of the CT and its tributaries, to define any alteration seen in the CT and its tributaries when pancreatic disease involves the portal venous system, to assess whether the appearance of the CT at CT enables differentiation between benign and malignant pancreatic diseases, and to assess whether
I From the Department of Radiology, McMaster University Faculty of Health Science, Hamilton, Ont, Canada. Received July 19, 1991; revision requested August 30; revision received and accepted October 10. Supported in part by the Sterling-Winthrop Imaging Research Institute, Canada. Address reprint requests to H.M., Department of Radiology, Medical College of Oita, 1-1 Idaigaoka, Hazama, Oita 879-56, Japan. RSNA, 1992
1. Frontal view of anatomy of the its tributaries. PV = portal vein, SV vein, SMV = superior mesentenic I = GT, 2 = RGEV, 3 = ASPDV, 4 =
GT and splenic
vein,
RCV, 5 = subpyloric vein, PSPDV, 8 = left gastroepiploic
6
=
MCV,
7
=
=
vein.
of the CT at CT contributes to the staging of pancreatic carcinoma. The anatomy of the pancreas is presented in Figure 1. The anterior surface of the head of the pancreas is drained mainly by the anterior supenor pancreatico-duodenal vein (ASPDV). The ASPDV is joined by the right gastroepiploic vein (RCEV), the right superior colic vein (RCV), and the subpyboric vein to form the CT. In some instances, the middle colic vein (MCV) also joins to form the CT. The RCV drains the right half of the transverse colon and the hepatic flexure, and the MCV drains the middle and left portions of the transverse colon. Both the RCV and the MCV nun within the transverse mesocobon. The RCEV proceeds along the greater curdemonstration
Abbreviations: ASPDV = pancreatico-duodenal vein, trunk, MCV = middle colic portal-superior mesenteric
PSPDV nal vein,
=
posterior RCV
RGEV = right nor mesenteric
=
superior right
superior
gastroepiploic
anterior superior GT = gastrocolic vein, P-SMVC = venous confluence,
pancreatico-duodecolic
vein,
vein, SMV
=
supe-
vein.
871
vature layers enters
of the stomach between the of the gastrocolic ligament and the right edge of the transverse mesocobon. CT features of the RGEV have been demonstrated previously (9). The RGEV and the colic veins, in effect, form the CT at the root of the transverse mesocobon. The subpybonic vein receives tributaries from the pylorus and the first part of the duodenum. The CT terminates in the night anterolateral aspect of the SMV, within 1-5 cm below its confluence with the
Table 1 Frequency
Visualized
Vein
Group A (n = 41)
Group B (n = 17)
GT RGEV RCV MCV ASPDV PSPDV
20 24 12 0 0 0
8 6 4 0 0 0
Note-Sixty-eight pancreatic diseases
Mean
AND
Sixty-four CT scans patients with pancreatic
Diameter (mm)
at CT
Tributaries
Seen on 5-mmSection Scan Group B (n = 10)
Mean
Diameter
(mm)
9 6 5 I 0 2
4.1 (2.6-4.7) 3.6 (2.0-4.2) 2.8 (2.0-3.3) NA NA NA
4.1 (4.0-4.4) 3.4(2.2-4.0) 3.0(2.0-4.0) 4.0 NA 2.0(2.0)
CT scans were obtained for 48 patients (30 in comparison [group BI). Numbers in parentheses are range of diameters.
group NA
=
A and 18 with not applicable.
b.
a.
PATIENTS
of the GT and Its
Seen on 10-mmSection Scan
splenic vein. The CT was reported to be found in 72%-100% of postmortem studies (5-8). In cases in which the CT is absent, the RCEV, the colic veins, the ASPDV, and the subpylonic veins drain separately or merge with each other before joining the SMV. The transverse mesocolon, which covers the anterior surface of the head and body of the pancreas and the second portion of the duodenum (11-13), becomes confluent near the level of the uncinate process of the pancreas with the root of the small bowel mesentery. At CT, the transverse mesocolon is identified as the fatty plane that extends from the pancreas, particularly at the bevel of the uncinate process, to the ventnally situated transverse colon, with the middle colic vessels coursing through it
(12,13).
of Visualization and Mean Diameter with Normal Portal Venous System
in Patients
METHODS were obtained disease (23
in 36 men
and 13 women, aged 25-89 years [mean, 60.8 yearsl). The patients were identified by review of the computerized medical records of all patients seen over a 3-year period at the McMaster University Health Science Center. Nineteen patients included in the study had cancer of the pancreas (17 in the head and two in the body and tail), (.)flC had cancer of the lower bile duct, one had ampullary cancer, and nine had chronic pancreatitis proved at pathologic examination by means of surgery or percutaneous biopsy. The radiobogic and clinical diagnosis of chronic pancreatitis in
the
remaining
six patients
was
made
on
the basis of imaging findings such as the presence of pancreaticolithiasis, nonobstructive dilatation of the pancreatic duct, or pseudocyst formation. Patients with peritoneal carcinomatosis and those who had recently undergone surgery were cxcluded from the study because thickened mesenteric septa could not be differentiated
from A model
the CT and 9800 scanner
its tributaries (GE Medical
tciim, Milwaukee) was used. 10-mm-thick sections were patients matic One
872
from the level dome to the level liter
of contrast
#{149} Radiology
at CT. Sys-
Contiguous acquired
in all
of the diaphragof the iliac crest.
medium
was
adminis-
d.
C.
Figure
were
2.
CT scans
obtained
with
show
normal
10-mm-thick
GT and
sections
its tributaries
in three
in a 67-year-old
different
man
with
patients.
hepatic
(a, b) Scans
metastasis
from
colon cancer. (c) Scan was obtained with 10-mm-thick sections in a 28-year-old woman with chronic pancreatitis. (d) Scan was obtained with 5-mm-thick sections in a 69-year-old woman with a small cancer of the head of the pancreas. The GT (straight arrow in a, c, and d) drains to the right anterolateral wall of the SMV at the level of the uncinate process of the head of the pancreas. RGEV (curved solid arrow in b and c) and RCV (open arrow in c) are also identifiable. D = duodenum, St = stomach. The arrowhead in d indicates a biliary stent.
tered
orally
scans were ministration
to each
patient
prior
obtained after intravenous of 75 mL of nonionic
to CT.
CT ad-
contrast
medium (iohexol, Omnipaque 350; Winthrop Pharmaceuticals, New York) by using an injection pump at a rate of I mL/
sec.
Twenty-two
selected
patients
underwent
scanning
with
contiguous
sections
through
atic tion
dium
area after of 50 mL
also
5-mm-thick
the pancre-
a second intravenous of the same contrast
at the same
rate.
These
injecme-
images
March
were
1992
targeted to the pancreatic area and were magnified (with a field of view of 20 HU) with a wide window width (450 HU). Thirty-nine CT examinations were obtamed with 10-mm-thick sections and 25 with 5-mm-thick sections. Seven patients underwent celiac artery angiography.
and
superior One patient
the
below vein,
RCV,
its confluence and, if visualized,
with
MCV,
ASPDV.
the
and
the
the consists
of Each
CT examination was retrospectively reviewed to establish (a) whether the CT could be seen; (Ii) whether the CT was situated below or anterior to the head of the pancreas; (c) the diameter of the CT and its tributaries; (d) the frequency of visualization of the PSPDV; (e) whether dilatation
(1) and
of these veins could be identified; the patency of the SMV, splenic vein, portal vein and the presence of other
collateral veins of the (g) whether 5-mm-thick the
portal system; or 10-mm-thick CT
and
sections
showed
ies most dilatation
clearly; (Ii) the relationship or occlusion of the CT
its tributarof to the
abnormality of the portal venous system and pancreas; (i) whether CT abnormalities could enable differentiation between benign and malignant diseases; and (j) whether CT abnormalities could facilitate staging of pancreatic carcinoma. CT scans were reviewed by three of the authors (H.M., F.P.M., D.E.M.) in conference. The maximum diameter of the CT and its tributaries was measured by using digital calipers on the hard-copy CT images. The medical records of all patients were
and
reviewed
extent
viewing
to determine
of disease. CT
scans,
the
nature
In addition angiograms
to reof seven
patients and ultrasound 36 patients were reviewed
(US) scans to assess
volvement
venous
of the
portal
of all in-
system.
Surgery and pathology records were gleaned to assess involvement of the tal venous system and the transverse socolon.
Images
series
of upper
or reports
viewed
to substantiate
also porme-
gastrointestinal
of endoscopy the
were findings
reof
esophageal or gastric vanices seen at CT. The CT scans of 30 consecutive patients who had metastatic disease of the liver proved at pathologic examination to arise from primary malignancies in organs other than the pancreas were also reviewed by using the same method. These 30 patients formed a comparison group of patients
who
would
have
a pathologic
venous
system.
with uous
not
be
expected
condition CT
scans
the same CT scanner 10-mm-thick sections.
scans were obtained Nonionic contrast
to
of the portal were
obtained
by using contigForty-one CT
in these 30 patients. medium (100 mL of
iohexol) was administered intravenously at a rate of I mL/sec. Each CT scan was reviewed for frequency of visualization and diameter of the CT and its constituent
Volume
182
#{149} Number
3
gency
sidered
location,
as de-
was calculated by two-by-two contintables. A value of P < .05 was constatistically significant.
mesenteric with can-
cer of the pancreas underwent CT arterial portography with 10-mm-thick sections. The CT was defined as the vein that is contiguous with the RCEV and that enters the right anterolateral aspect of the SMV 1-5 cm splenic
veins at their expected scribed above. Statistical correlation using 2 analysis with
RESULTS
in six obtained with 5-mm-thick sections. The mean diameter of the RCEV was 3.4 mm (Table 1). The CT was seen on all CT scans in which it was identifiable to drain into the anterolateral aspect of the SMV at the level of the uncinate process of the head of the pancreas after running along the anterior surface of the head of the pancreas for variable
On the basis of the surgical records and radiobogic features, patients with pancreatic disease could be divided into four categories with respect to
lengths
the major abnormalities venous system.
the
of the
portal
(Fig
Patients
2).
with
Splenic These
Isolated Vein
Occlusion
of
five
patients had chronic Large pseudocysts in the tail of the pancreas and/or splenic hilum were surgically drained in all five patients. Isolated occlusion of the splenic vein was confirmed at angiography in two patients. The portalpancreatitis.
Patients
with
Venous
System
Normal
Portal
Eighteen patients with pancreatic diseases (nine with cancer of the head of the pancreas, one with ampullary cancer, one with cancer of the lower bile duct, and seven with chronic pancreatitis) were included. No associated pseudocyst formation was seen in patients with pancreatitis. Sectional imaging showed an essentially normal portal venous system in these patients. No pancreatic cancer affected the main portal vein, the SMV, or the splenic vein. Three patients with cancer of the head of the pancreas had normal angiograms, and six had no evidence of involvement of the portal venous system at laparotomy. Seventeen CT scans with 10mm-thick sections and 10 with 5-mmthick sections were obtained in these 18 patients. The frequency of visualization and mean diameter of the CT and its tributaries Two
are summarized patients (one
with
in Table 1. pancreatic
cancer and one with ampullary cancer) underwent tumor resection. Six underwent choledochojejunostomy because of the presence of hepatic metastasis (n = 3) or tumor infiltration to the celiac artery (n = 3) that were detected at CT and sonography. Three patients chose to undergo biliary stent placement after CT-guided biopsy. This subgroup of 18 patients plus the comparison group of 30 patients gives a total of 48 patients (68 CT scans) who had no abnormality in the portal venous system. The CT was identified in 28 of 58 scans obtained with 10-mm-thick sections (48.3%) and in nine of 10 scans obtained with 5-mm-thick sections (90%). The mean diameter RCEV tamed
was with
of the CT was 4.1 mm. identified in 30 scans 10-mm-thick sections
The oband
superior
mesenteric
venous
axis
ap-
peared normal on both CT and US scans in each patient. The main splenic vein, with collateral veins runfling in the splertic hilum and the gastrohepatic ligament and along the wall of the gastric fundus, was not visualized on either CT and US scans. Six CT scans were obtained with 10mm-thick sections and five with 5-mm-thick sections. The CT was identified in all five patients in CT scans obtained with either 10-mm (50%) or 5-mm-thick sections (100%), with a mean diameter of 5.6 mm (range, 5.0-8.0 mm) (Table 2, Fig 3). Each CT seen in this subgroup was interpreted as being
dilated. A dilated RCEV was associated with a dilated CT in all cases. The RCV was identifiable on both 10mm-section and 5-mm-section scans in two patients. The MCV and the PSPDV were identified on 5-mm-section scans. The ASPDV and the subpyloric vein were not identified.
Patients with of the P-SMVC the CT Entry
Occlusion Above
or Stenosis the Level of
This group consisted tients (two with cancer
of the
the
pancreas,
cancer
body
and
two tail
with
of the
of five pahead
of
of the
pancreas,
and
one
with chronic pancreatitis). Angiographic evidence of confluence occlusion or stenosis was obtained in two patients with cancer of the head of the pancreas. Tumor invasion to the P-SMVC
was
demonstrated
at surgery
in one patient with cancer of the body and tail of the pancreas (Fig 4). In the remaining two patients, significant stenosis
of the
P-SMVC
surrounded
Radiology
873
#{149}
Figure isolated
3.
CT scans splenic vein
obtained
with
year-old
man
show CT dilatation in occlusion. (a, b) Scans
5-mm-thick
in a 58(Cy) of the pancreatic tail show a dilated CT (straight arrow in b) and a dilated RGEV (curved solid with
sections
a pseudocyst
arrow in a and b). The RCV (open arrow b) appears normal. St = stomach. Contrast medium is present in the colon and in a small bowel loop.
in
by tumor mass (cancer of the body and tail) or pseudocyst (chronic pancreatitis) was seen on sectional images. Numerous collateral veins
around
the gastric
mesentery
were
fundus
or in the
also
observed. Nine with 10-mmthree scans with
scans were obtained thick sections and 5-mm-thick sections. The CT and RCEV on all CT scans. Their
Table 2 Frequency in Patients
were identified diameters were
greater than 5.0 mm. The veins were interpreted as being dilated. The RCV and MCV were identified on all 5-mmsection scans and could be interpreted as being dilated. The ASPDV, with diameter
less
able
than
2.2
mm,
in 5-mm-section
interpreted
was
scans
as being
GT RGEV RCV MCV ASPDV PSPDV
3;
4, 5).
Figs
Tumor resection was not performed in four patients with pancreatic cancer. In one patient with cancer of the body and tail of the pancreas, invasion to the P-SMVC was
at laparotomy,
while
Note.-Eleven
with chronic by pseudocyst
vein
mesen-
Table 3 Frequency in Patients
complicated were in-
Sectional
imaging
occlusion sis (n
(n
7) or significant
Note-Twelve with chronic
showed
tomy.
served.
were
tamed,
including
raphy sections.
The
scan,
with
CT was
scans
were
a CT arterial
ob-
portog-
10-mm-thick
obliterated
and Mean Diameter Occlusion or Stenosis
Seen on 10-mmSection Scan (n = 9)
Mean
9 9 4 3 0 0
6.7 6.9 5.2 6.5
by a barge
cancer tumor or a pseudoall CT scans. The RCEV was visualized and was dilated in all patients in this subgroup of 11 scans
The
RCV,
MCV,
identifiable
all scans and were ing dilated in most ble4). No
patient
and
in over
with
interpreted of these pancreatic
Surgery
cases
of as be(Ta-
cancer
showed
underwent
tumor extension to the root of the transverse mesocobon in three patients with cancer of the head of the pancreas (Fig 6) and extension of the pseudocyst to the lesser sac through the transverse mesocobon in one patient with pancreatitis.
in
one
patient
with
pancre-
atitis, the RGEV was not identifiable because of the presence of metalic clips used in a previous cyst-gastros-
874
#{149} Radiology
resection.
PSPDV
one-half
pancreatic
In
chronic
5.6(5.2-6.2) 5.2(4.0-5.6) 2.2(2.2) 4.4 NA 1.6
pancreatitis.
Numbers
in paren.
of the CT and Its Tributaries at CT Above the Level of the CT Entry
Diameter (mm)
Seen on 5-mmSection Scan (n = 3)
(5.0-8.8) (5.0-7.8) (4.0-7.8) (4.0-7.8) NA NA
Mean
Diameter
(mm)
3 3 3 3 2 0
7.3(5.3-8.9) 7.9(6.1-11.0) 8.2(5.5-13.7) 8.7(4.7-13.7) 2.1 (2.0-2.2) NA
CT scans were obtained for five patients (four with cancer of the pancreas and pancreatitis). Numbers in parentheses are range of diameters. NA = not applicable.
cyst
(78.6%).
with
Diameter (mm)
one
steno-
= 1) of the P-SMVC. Numerous collateral veins in the mesentery and within the hepatic hibum were ob-
CT
of Visualization with P-SMVC
GT RGEV RCV MCV ASPDV PSPDV
(six with cancer of pancreas and two
cluded.
Fourteen
Mean
5 5 2 I 0 1
5.5 (5.0-8.0) 7.5 (6.2-10.0) 2.0 (2.0) NA NA NA
CT scans were obtained for five patients of diameters. NA = not applicable.
Vein Visualized
or Stenosis the CT
pancreatitis formation) =
Seen on 5-mmSection Scan (n = 5)
Diameter (mm)
at CT
Tributaries
tumor found
splenic
Occlusion including
Eight patients head of the
3 4 2 0 0 0
theses are range
Entry
the
Mean
of the CT and Its
angiograms
showed occlusion of the but a patent portal-superior tenic vein (Fig 4).
Patients with of the P-SMVC
Isolated
Seen on 10-mmSection Scan (n = 6)
Visualized
was
(Table
and Mean Diameter Splenic Occlusion
Visualization
with
Vein
identifi-
and
normal
of
CT Findings in 5-mm-section versus 10-mm-section Scans In patients who tab venous system, 5-mm-section
scans
had a normal porfindings in the were
statistically
superior to those in the 10-mm-section scans regarding depiction of a normal CT (P < .05). There was no statistical
difference
between
5-mm-
and 10-mm-section scans regarding depiction of a normal RCEV or a normal RCV (Table 1). There was also no statistical
difference
between
5-mm-
March
1992
and 10-mm-section scans in depiction of dilated CT, RCEV, RCV, or MCV (Tables 2-4).
CT Findings in Pancreatic versus Pancreatitis
Cancer
There was no statistically significant difference in the rate of occurrence of abnormal CT findings (dilatation and obliteration by mass) in patients with pancreatic cancer and chronic pancreatitis (Table 5).
In 10 patients
with
pancreatic
cer who had an abnormality portal venous system (eight cen of the head of the pancreas two with cancer of the body interpretation of CT findings ysis of the appearance of the its tributaries of occlusion
confirmed or stenosis
volvement) or the vein
of the
splenic
(n
=
8) (which
when
vein
(ii
=
2)
mesenteric could
interpreting
without consideration of the appearance of the CT). In a patient with cancer of the body and tail of the pancreas, the preoperative diagnosis on the basis of findings at CT and angiography was of isolated splenic vein occlusion (resectabbe); however, diagnosis
the presence (tumor in-
portal-superior
pected
can-
of the with canand and tail), by analCT and
be sus-
CT findings
on
the
basis
of the
finding
of
dilatation of the CT, RCV, and MCV could be tumor extension to the P-SMVC (unresectable) (Fig 4). In the remaining nine patients with pancreatic cancer, interpretation ings at CT on the basis
of the of abnormal
find-
dilatation on occlusion of the CT did not result in a change of staging from operable to inoperable with regard to portal venous involvement.
DISCUSSION The CT runs along the anterior pect of the head of the pancreas.
Figure 4. CT scans show GT due to tumor invasion (stenosis) and splenic vein (a, b) Scans obtained with tions in a 59-year-old man
asIt
dilatation of the of the P-SMVC (occlusion). 5-mm-thick sec-
with cancer of the body and tail of the pancreas show dilated GT (large white straight arrow in b). Dilated RGEV (curved solid white arrow in a and
b) and
RCV
(open
white
arrow
in b)
are continuous to GT. The MCV (small white arrows in a and b) is also dilated. ASPDV (black arrow in b) is identifiable.
The Ar-
rowhead in a indicates the gastroduodenal artery. (c) Celiac angiogram depicts occlusion of the splenic vein and dilatation of the RGEV (curved arrows) and the GT (solid black arrow), which drains into SMV (open
arrow). (d) The P-SMVC (arrows), depicted in venous phase of the superior mesenteric arteniogram, was interpreted as normal preoperatively. Demonstration of dilatation of the RCV and MCV at CT (shown in a and b) suggested
a.
b.
Figure 5. CT scans tions in a 25-year-old splenic vein are not
arrow Volume
tumor
extension
to the
P-SMVC.
d.
C.
in a and 182
show CT dilatation in stenosis of the man with chronic pancreatitis show occluded but demonstrate significant
c. P-SMVC a large stenosis
above the CT entry to the SMV. pseudocyst (Cy) occupying almost (straight arrows in a and b). The
CT scans obtained with 10-mm-thick secthe entire pancreas. The P-SMVC and the CT (arrow in c) and the RGEV (curved
b) are dilated.
Number
#{149}
3
Radiology
#{149} 875
drains into the right anterobateral aspect of the SMV after receiving those veins coursing within the transverse mesocobon
(the
MCV),
RCEV,
in addition
RCV,
and
to the ASPDV
(6-
expectation
that
an assessment
.:‘
r,r
9). The transverse mesocobon covers the anterior surface of the head and body of the pancreas and the second part of the duodenum (11-13). An
u
r:;’
of the
CT and its tributaries may lead to a more precise understanding of pathologic conditions of the portal veins or
prompted In patients with
this study. no major abnor-
pancreas
mality
the
of the
normal
portal
(10-mm-thick
thick CT
venous
CT was sections)
sections) scans.
in 48%
to 90%
(5-mm-
on contrast-enhanced
Findings
in our
firmed that the the level of the the head of the
an important
system,
identifiable
study
CT enters uncinate pancreas.
vascular
con-
the SMV at process of This may be
landmark
on
CT scans of the pancreas, representing the root of the transverse mesocobon as it becomes confluent with the root of the small bowel mesentery. The RCEV was also readily recognizable on contrast-enhanced CT scans because of its characteristic hairpin course, running from left to night in the greater omentum near the greater curvature of the stomach. Near the pylorus, the RCEV turns downward
and
backward,
2-6).
forming
Delineation
MCV
RCV
may
depend
on CT scans
amount of the was
on the
fat and the position colon. The ASPDV seen on CT scans even if obtained with thin sec-
were
The
tions.
and
of body transverse rarely
they
the CT (Figs
of the
to section its small
ASPDV
may
misregistration caliber and
because of its oblique or hor-
course.
A CT 5 mm at and was in both scans in
with a diameter greater than CT is considered abnormal identifiable nearly constantly 5-mmand 10-mm-section CT our study. Dilatation of the
represent
occlusive
changes
of the splenic vein or the P-SMVC above the bevel of the CT entry into the SMV. Dilatation of the RCEV (diameter > 5 mm) was always observed in these situations. Hemodynamically, the RCEV may play a role as a collateral pathway in cases of occlusion
of
the
splenic
vein
and
may
also be dilated because of venous gestion that occurs when the CT, SMV (at the CT entry), or P-SMVC occluded. The RCV and MCV are
mal
in patients
occlusion and with occlusion staging
876
of
cancer
#{149} Radiology
with
isolated
conis nor-
splenic
are dilated in patients of the P-SMVC. For of
the
Figure
6.
CT scans show CT obliteration with occlusion of the P-SMVC. Scans were obtained with (a) 10-mm-thick sections and (b) 5-mm-thick sections in a 66-year-old patient with cancer of the head of the pancreas. The P-SMVC and the CT are obliterated by a large tumor mass of
the head
of the pancreas
The RCEV
(M).
(curved
in a) is encased by tumor mass. Dilatation of the white arrows in a and b) are also noted. Extension socolon was found during surgery. a = superior SMV.
Table 4 Frequency
of Visualization with P-SMVC
in Patients
and Mean Diameter Occlusion or Stenosis
Seen on 10-mmSection Scan (n = 7)
Vein Visualized CT RGEV RCV MCV ASPDV PSPDV
Mean
in a) is dilated. arrow to the artery,
The SMV (black
in b) and the MCV root of the transverse Du = duodenum,
arrow
(small mev =
of the CT and Its Tributaries at CT including the Level of the CT Entry
Diameter
(mm)
0 5 4 5 0 5
Note-Fourteen creas and two with plicable.
arrow
RCV (open of cancer mesentenc
Seen on 5-mmSection Scan (n = 7)
NA 7.2 (6.0-10.0) 5.8 (3.3-8.0) 5.0(4.2-7.0) NA 8.8 (7.0-10.0)
Mean
0 6 5 3 0 6
Diameter (mm)
NA 6.6(5.0-10.0) 5.6(4.0-7.8) 5.8(3.0-8.9) NA 9.8(6.0-12.0)
CT scans were obtained for eight patients (six with cancer of the head chronic pancreatitis). Numbers in parentheses are range of diameters.
of the panNA = not ap.
be vulnerable
izontal
CT may
b.
a.
pancreas,
rec-
ognition of dilatation of the RCV MCV at CT may provide the clue
and to
differentiate isolated splenic vein occlusion (resectable) from involvement of the P-SMVC (unresectabbe) in patients with cancer of the body and tail of the pancreas (Fig 4). Similarly, in patients with cancer of the head of the pancreas, the findings of dilatation of the CT and its tributaries at CT may suggest tumor extension to the
P-SMVC
(unresectabbe)
angiograms mab P-SMVC.
or CT
Dilatation
of the
even scans
PSPDV
when
show
a nor-
has been
demonstrated at CT in patients with occlusion of other pancreatico-duodenal veins (4). Likewise, occlusion of the posterior pancreatico-duodenal veins can cause dilatation of the ASPDV and the CT. Portal hypertension may be one of the causes for dibatation of the CT. The CT can also be dilated as a collateral pathway
through tients
the with
RCV localized
or the
MCV
occlusion
in paof the
SMV below the level of the CT entry. Unfortunately, no such case was seen in the limited number of patients reviewed in our study. Obliteration of the CT by a large tumor mass or pseudocyst in the head of the pancreas was an indicator of anterior extension of disease to the root of the transverse mesocobon. The association of occlusion of the SMV and the P-SMVC may be the result of their close anatomic relationship with the CT. Dilatation of the RCEV was also associated with this finding, presumabby as a result of venous congestion. The RCV and/or MCV can also be dilated. Tumor extension can be anatomically localized in the SMV at the CT entry, not reaching the P-SMVC. The CT finding of obliteration of the CT by tumor mass may also help confirm inoperability of March
1992
4. !
Table 5 CT Findings
at CT in Patients
with
Pancreatic
Patients
with
Pancreatic
Chronic
I
Normal
(n
visualization
32)
=
Comparison
Pancreatitis (n = 32)
8
9
20
4
6
21
Abnormal Obliteration
9 9
11 5
0 0
dilatation by mass
5.
Group (n = 41)
Not identified
H, Miyake posterior
H, Aikawa H, et al. superior pancreaticoduode-
nal vein: recognition
Croup
Patients
with Cancer CT Finding
and in Comparison
Diseases
Mon lated
6.
7.
Di-
with CT and clinical
significance in patients with pancreaticobiliary carcinomas. Radiology 1991; 181 :793800. Falconer CWA, Griffiths E. The anatomy of the blood vessels in the region of the pancreas. BrJ Surg 1950; 37:334-344.
Douglass BE, Baggenstoss AH, Hollinshead WH. The anatomy of the portal vein and its tributaries. Surg Gynecol 91:562-576. Reichardt W, Cameron R.
Obstet
1950;
Anatomy
of the
pancreatic veins: a postmortem and clinical phlebographic investigation. Acta Radiol CT
t;T
KCEV
: Figure
4sI.t.t.
kGV
: 7.
Flow
:
chart
CT and major portal ment with pancreatic
depicts
venous cancer.
1d
system,
CT findings
branch
diseases. Recognition of abnormalities of the CT on CT scans may improve the accuracy of staging of cancer of the pancreas by clarifying the degree of involvement of the portal venous
d*I.t.t&
involve-
for
as well
identification the transverse
as by
assisting
Volume
182
#{149} Number
3
References
2.
3.
Kneeland portocaval Radiology
venous
pathways
vein occlusion:
11.
12.
Kazam E, Rubenstein WA, Markise JA, Whalen JP, Zirinsky K. Anatomy. In: Margulis AR, Burhenne HJ, eds. Alimentary tract radiology. 4th ed. St Louis: MosbyYear Book, 1989; 231-271. Kazam E, Auh YH, Rubenstein WA, Whalen JP. Cross-sectional anatomy of the abdomen. In: Taveras JM, Ferrucci JT, eds. Radiology. Philadelphia: Lippincott, 1986. Zinnsky K, Auh YH, Rubenstein WA,
A, Butori
H. and
Venous its relations Anat Clin
Marn CS, Glazer GM, Williams DM, Francis IR. CT-angiographic correlation of collateral
to
cal analysis.
C, Bourgeon
1983; 5:103-113.
9.
10.
1.
1980; 21:33-41. Birtwisle Y, Ferrari
P, Hannoun L, Richelme drainage of the pancreas to pancreatic phlebography.
the
of tumor extension mescocobon. U
Acknowledgments: We thank Monika Femer for preparation of this manuscript and Hiroyuki Shimamoto, MD, for his assistance with statisti-
pancreatic cancer in such cases. Figure 7 shows the relationship between CT findings of the CT and its tributaries and major portal venous abnormalities in patients with pancreatic cancer. Although the CT findings of abnormalities of the CT and its tributaries could not enable differentiation of benign from malignant pancreatic disease, they helped confirm involvement of the major branches of the portal venous system with pancreatic
8.
splenic
Radiol-
ogy 1990; 175:375-380. Freeny PC, Marks WM, Ryan JA, Traverso LW. Pancreatic ductal adenocarcinoma: diagnosis and staging with dynamic CT. Radiology 1988; 166:125-133.
Warwick anatomy.
R, Williams PL, eds. 35th ed. Edinburgh:
1973; 1257-1270. Meyers MA. Intraperitoneal malignancies. In: Meyers radiology of the abdomen.
York: Springer-Verlag, 13.
in isolated
new observations.
Meyers
MA,
Oliphant
The peritoneal pathways
Gray’s Longman,
spread of MA, ed. Dynamic 3rd ed. New
1988; 91-175. M, Berne
ligaments
AS, et al.
and mesenteries:
of intraabdominal spread 1987; 163:593-604.
of dis-
ease. Radiology
JB, Whalen JP, Kazam E. The space: CT with MR correlation. 1985; 156:453-460.
______
#{149} R77
______
Mori,
MD
Frank
P. McGrath,
#{149}
The Gastrocolic CT Evaluation’ Dilatation colic
or occlusion
trunk
portal
(GT)
venous
logic
may
of the gastropatho-
To evaluate
and
the
surgical-pathologic
were
A normal was
studied
GT (2.6-4.7-mm
identifiable
group
for comparison.
in 48%
in CT scans
diameter) of the
obtained
control
with
mm-thick sections and in 90% scans obtained with 5-mm-thick
tions. tients
The CT was with isolated
clusion
and
dilated splenic
in five
patients
10-
of CT sec-
in five pavein ocwith
occlusion
or stenosis of the portalmesenteric vein confluence (P-SMVC) above the level of the CT entry into the superior mesenteric vein. The CT was obliterated in eight patients and was associated with P-SMVC occlusion. Findings at surgery confirmed tumor extension into superior
the root in three pancreas. however,
of the transverse mesocolon patients with cancer of the Abnormal findings at CT, do not enable differentia-
tion between benign pancreatic diseases.
and malignant
Index terms: Pancreas, CT, 70.1211 creas, neoplasms, 77.321 #{149} Pancreatitis, Veins, CT, 959.1211 #{149} Veins, gastrocolic, 959.92 #{149} Veins, mesenteric, 959.92 Radiology
1992;
182:871-877
Pan77.291
#{149}
E. Malone,
Its
and
MB
Giles
#{149}
W. Stevenson,
MB
Tributaries:
HE pancreatico-duodenal
along nor-
records of 21 patients with cancer of the pancreas and 15 patients with chronic pancreatitis were reviewed retrospectively. The CT examinations of 30 patients with metastatic disease of the liver and no known pancreatic disease
T
to a
mal and abnormal appearances of the GT and its tributaries at computed tomography (CT), the CT scans, angiograms,
#{149} Dermot
Trunk
be a clue
or pancreatic
condition.
MB
and gastrocolic the anterior
faces of the tle attention
head has
veins trunk (GT) nun and posterior sur-
of the pancreas. Litbeen paid to their
cross-sectional imaging dilatation or occlusion a pathologic condition veins or the pancreas. the posterior superior duodenal ondary
(1-4). Their may be clues in the portal Dilatation of pancreatico-
vein (PSPDV) may to occlusive changes
to
be secin the
other pancreatico-duodenal veins and/or the portal-superior mesenteric venous confluence (P-SMVC) The GT comprises veins of the
Figure (4).
transverse mesocobon and one of the pancreatico-duodenal veins. The CT nuns transversely in front of the infenor portion of the head of the pancreas and drains into the right lateral wall of the superior mesenteric vein (SMV) (5-8). Although its location is usually constant, one author has reported the CT to be anatomically bocated below the head of the pancreas (9). Evaluation of the portal vein and SMV with CT has a robe in staging of pancreatic carcinoma (10). An assessment with CT of the CT and its tnbutaries may lead to a more precise understanding of the extent of a pathologic condition arising from the pancreas. The purposes of this study were to define normal CT anatomy of the CT and its tributaries, to define any alteration seen in the CT and its tributaries when pancreatic disease involves the portal venous system, to assess whether the appearance of the CT at CT enables differentiation between benign and malignant pancreatic diseases, and to assess whether
I From the Department of Radiology, McMaster University Faculty of Health Science, Hamilton, Ont, Canada. Received July 19, 1991; revision requested August 30; revision received and accepted October 10. Supported in part by the Sterling-Winthrop Imaging Research Institute, Canada. Address reprint requests to H.M., Department of Radiology, Medical College of Oita, 1-1 Idaigaoka, Hazama, Oita 879-56, Japan. RSNA, 1992
1. Frontal view of anatomy of the its tributaries. PV = portal vein, SV vein, SMV = superior mesentenic I = GT, 2 = RGEV, 3 = ASPDV, 4 =
GT and splenic
vein,
RCV, 5 = subpyloric vein, PSPDV, 8 = left gastroepiploic
6
=
MCV,
7
=
=
vein.
of the CT at CT contributes to the staging of pancreatic carcinoma. The anatomy of the pancreas is presented in Figure 1. The anterior surface of the head of the pancreas is drained mainly by the anterior supenor pancreatico-duodenal vein (ASPDV). The ASPDV is joined by the right gastroepiploic vein (RCEV), the right superior colic vein (RCV), and the subpyboric vein to form the CT. In some instances, the middle colic vein (MCV) also joins to form the CT. The RCV drains the right half of the transverse colon and the hepatic flexure, and the MCV drains the middle and left portions of the transverse colon. Both the RCV and the MCV nun within the transverse mesocobon. The RCEV proceeds along the greater curdemonstration
Abbreviations: ASPDV = pancreatico-duodenal vein, trunk, MCV = middle colic portal-superior mesenteric
PSPDV nal vein,
=
posterior RCV
RGEV = right nor mesenteric
=
superior right
superior
gastroepiploic
anterior superior GT = gastrocolic vein, P-SMVC = venous confluence,
pancreatico-duodecolic
vein,
vein, SMV
=
supe-
vein.
871
vature layers enters
of the stomach between the of the gastrocolic ligament and the right edge of the transverse mesocobon. CT features of the RGEV have been demonstrated previously (9). The RGEV and the colic veins, in effect, form the CT at the root of the transverse mesocobon. The subpybonic vein receives tributaries from the pylorus and the first part of the duodenum. The CT terminates in the night anterolateral aspect of the SMV, within 1-5 cm below its confluence with the
Table 1 Frequency
Visualized
Vein
Group A (n = 41)
Group B (n = 17)
GT RGEV RCV MCV ASPDV PSPDV
20 24 12 0 0 0
8 6 4 0 0 0
Note-Sixty-eight pancreatic diseases
Mean
AND
Sixty-four CT scans patients with pancreatic
Diameter (mm)
at CT
Tributaries
Seen on 5-mmSection Scan Group B (n = 10)
Mean
Diameter
(mm)
9 6 5 I 0 2
4.1 (2.6-4.7) 3.6 (2.0-4.2) 2.8 (2.0-3.3) NA NA NA
4.1 (4.0-4.4) 3.4(2.2-4.0) 3.0(2.0-4.0) 4.0 NA 2.0(2.0)
CT scans were obtained for 48 patients (30 in comparison [group BI). Numbers in parentheses are range of diameters.
group NA
=
A and 18 with not applicable.
b.
a.
PATIENTS
of the GT and Its
Seen on 10-mmSection Scan
splenic vein. The CT was reported to be found in 72%-100% of postmortem studies (5-8). In cases in which the CT is absent, the RCEV, the colic veins, the ASPDV, and the subpylonic veins drain separately or merge with each other before joining the SMV. The transverse mesocolon, which covers the anterior surface of the head and body of the pancreas and the second portion of the duodenum (11-13), becomes confluent near the level of the uncinate process of the pancreas with the root of the small bowel mesentery. At CT, the transverse mesocolon is identified as the fatty plane that extends from the pancreas, particularly at the bevel of the uncinate process, to the ventnally situated transverse colon, with the middle colic vessels coursing through it
(12,13).
of Visualization and Mean Diameter with Normal Portal Venous System
in Patients
METHODS were obtained disease (23
in 36 men
and 13 women, aged 25-89 years [mean, 60.8 yearsl). The patients were identified by review of the computerized medical records of all patients seen over a 3-year period at the McMaster University Health Science Center. Nineteen patients included in the study had cancer of the pancreas (17 in the head and two in the body and tail), (.)flC had cancer of the lower bile duct, one had ampullary cancer, and nine had chronic pancreatitis proved at pathologic examination by means of surgery or percutaneous biopsy. The radiobogic and clinical diagnosis of chronic pancreatitis in
the
remaining
six patients
was
made
on
the basis of imaging findings such as the presence of pancreaticolithiasis, nonobstructive dilatation of the pancreatic duct, or pseudocyst formation. Patients with peritoneal carcinomatosis and those who had recently undergone surgery were cxcluded from the study because thickened mesenteric septa could not be differentiated
from A model
the CT and 9800 scanner
its tributaries (GE Medical
tciim, Milwaukee) was used. 10-mm-thick sections were patients matic One
872
from the level dome to the level liter
of contrast
#{149} Radiology
at CT. Sys-
Contiguous acquired
in all
of the diaphragof the iliac crest.
medium
was
adminis-
d.
C.
Figure
were
2.
CT scans
obtained
with
show
normal
10-mm-thick
GT and
sections
its tributaries
in three
in a 67-year-old
different
man
with
patients.
hepatic
(a, b) Scans
metastasis
from
colon cancer. (c) Scan was obtained with 10-mm-thick sections in a 28-year-old woman with chronic pancreatitis. (d) Scan was obtained with 5-mm-thick sections in a 69-year-old woman with a small cancer of the head of the pancreas. The GT (straight arrow in a, c, and d) drains to the right anterolateral wall of the SMV at the level of the uncinate process of the head of the pancreas. RGEV (curved solid arrow in b and c) and RCV (open arrow in c) are also identifiable. D = duodenum, St = stomach. The arrowhead in d indicates a biliary stent.
tered
orally
scans were ministration
to each
patient
prior
obtained after intravenous of 75 mL of nonionic
to CT.
CT ad-
contrast
medium (iohexol, Omnipaque 350; Winthrop Pharmaceuticals, New York) by using an injection pump at a rate of I mL/
sec.
Twenty-two
selected
patients
underwent
scanning
with
contiguous
sections
through
atic tion
dium
area after of 50 mL
also
5-mm-thick
the pancre-
a second intravenous of the same contrast
at the same
rate.
These
injecme-
images
March
were
1992
targeted to the pancreatic area and were magnified (with a field of view of 20 HU) with a wide window width (450 HU). Thirty-nine CT examinations were obtamed with 10-mm-thick sections and 25 with 5-mm-thick sections. Seven patients underwent celiac artery angiography.
and
superior One patient
the
below vein,
RCV,
its confluence and, if visualized,
with
MCV,
ASPDV.
the
and
the
the consists
of Each
CT examination was retrospectively reviewed to establish (a) whether the CT could be seen; (Ii) whether the CT was situated below or anterior to the head of the pancreas; (c) the diameter of the CT and its tributaries; (d) the frequency of visualization of the PSPDV; (e) whether dilatation
(1) and
of these veins could be identified; the patency of the SMV, splenic vein, portal vein and the presence of other
collateral veins of the (g) whether 5-mm-thick the
portal system; or 10-mm-thick CT
and
sections
showed
ies most dilatation
clearly; (Ii) the relationship or occlusion of the CT
its tributarof to the
abnormality of the portal venous system and pancreas; (i) whether CT abnormalities could enable differentiation between benign and malignant diseases; and (j) whether CT abnormalities could facilitate staging of pancreatic carcinoma. CT scans were reviewed by three of the authors (H.M., F.P.M., D.E.M.) in conference. The maximum diameter of the CT and its tributaries was measured by using digital calipers on the hard-copy CT images. The medical records of all patients were
and
reviewed
extent
viewing
to determine
of disease. CT
scans,
the
nature
In addition angiograms
to reof seven
patients and ultrasound 36 patients were reviewed
(US) scans to assess
volvement
venous
of the
portal
of all in-
system.
Surgery and pathology records were gleaned to assess involvement of the tal venous system and the transverse socolon.
Images
series
of upper
or reports
viewed
to substantiate
also porme-
gastrointestinal
of endoscopy the
were findings
reof
esophageal or gastric vanices seen at CT. The CT scans of 30 consecutive patients who had metastatic disease of the liver proved at pathologic examination to arise from primary malignancies in organs other than the pancreas were also reviewed by using the same method. These 30 patients formed a comparison group of patients
who
would
have
a pathologic
venous
system.
with uous
not
be
expected
condition CT
scans
the same CT scanner 10-mm-thick sections.
scans were obtained Nonionic contrast
to
of the portal were
obtained
by using contigForty-one CT
in these 30 patients. medium (100 mL of
iohexol) was administered intravenously at a rate of I mL/sec. Each CT scan was reviewed for frequency of visualization and diameter of the CT and its constituent
Volume
182
#{149} Number
3
gency
sidered
location,
as de-
was calculated by two-by-two contintables. A value of P < .05 was constatistically significant.
mesenteric with can-
cer of the pancreas underwent CT arterial portography with 10-mm-thick sections. The CT was defined as the vein that is contiguous with the RCEV and that enters the right anterolateral aspect of the SMV 1-5 cm splenic
veins at their expected scribed above. Statistical correlation using 2 analysis with
RESULTS
in six obtained with 5-mm-thick sections. The mean diameter of the RCEV was 3.4 mm (Table 1). The CT was seen on all CT scans in which it was identifiable to drain into the anterolateral aspect of the SMV at the level of the uncinate process of the head of the pancreas after running along the anterior surface of the head of the pancreas for variable
On the basis of the surgical records and radiobogic features, patients with pancreatic disease could be divided into four categories with respect to
lengths
the major abnormalities venous system.
the
of the
portal
(Fig
Patients
2).
with
Splenic These
Isolated Vein
Occlusion
of
five
patients had chronic Large pseudocysts in the tail of the pancreas and/or splenic hilum were surgically drained in all five patients. Isolated occlusion of the splenic vein was confirmed at angiography in two patients. The portalpancreatitis.
Patients
with
Venous
System
Normal
Portal
Eighteen patients with pancreatic diseases (nine with cancer of the head of the pancreas, one with ampullary cancer, one with cancer of the lower bile duct, and seven with chronic pancreatitis) were included. No associated pseudocyst formation was seen in patients with pancreatitis. Sectional imaging showed an essentially normal portal venous system in these patients. No pancreatic cancer affected the main portal vein, the SMV, or the splenic vein. Three patients with cancer of the head of the pancreas had normal angiograms, and six had no evidence of involvement of the portal venous system at laparotomy. Seventeen CT scans with 10mm-thick sections and 10 with 5-mmthick sections were obtained in these 18 patients. The frequency of visualization and mean diameter of the CT and its tributaries Two
are summarized patients (one
with
in Table 1. pancreatic
cancer and one with ampullary cancer) underwent tumor resection. Six underwent choledochojejunostomy because of the presence of hepatic metastasis (n = 3) or tumor infiltration to the celiac artery (n = 3) that were detected at CT and sonography. Three patients chose to undergo biliary stent placement after CT-guided biopsy. This subgroup of 18 patients plus the comparison group of 30 patients gives a total of 48 patients (68 CT scans) who had no abnormality in the portal venous system. The CT was identified in 28 of 58 scans obtained with 10-mm-thick sections (48.3%) and in nine of 10 scans obtained with 5-mm-thick sections (90%). The mean diameter RCEV tamed
was with
of the CT was 4.1 mm. identified in 30 scans 10-mm-thick sections
The oband
superior
mesenteric
venous
axis
ap-
peared normal on both CT and US scans in each patient. The main splenic vein, with collateral veins runfling in the splertic hilum and the gastrohepatic ligament and along the wall of the gastric fundus, was not visualized on either CT and US scans. Six CT scans were obtained with 10mm-thick sections and five with 5-mm-thick sections. The CT was identified in all five patients in CT scans obtained with either 10-mm (50%) or 5-mm-thick sections (100%), with a mean diameter of 5.6 mm (range, 5.0-8.0 mm) (Table 2, Fig 3). Each CT seen in this subgroup was interpreted as being
dilated. A dilated RCEV was associated with a dilated CT in all cases. The RCV was identifiable on both 10mm-section and 5-mm-section scans in two patients. The MCV and the PSPDV were identified on 5-mm-section scans. The ASPDV and the subpyloric vein were not identified.
Patients with of the P-SMVC the CT Entry
Occlusion Above
or Stenosis the Level of
This group consisted tients (two with cancer
of the
the
pancreas,
cancer
body
and
two tail
with
of the
of five pahead
of
of the
pancreas,
and
one
with chronic pancreatitis). Angiographic evidence of confluence occlusion or stenosis was obtained in two patients with cancer of the head of the pancreas. Tumor invasion to the P-SMVC
was
demonstrated
at surgery
in one patient with cancer of the body and tail of the pancreas (Fig 4). In the remaining two patients, significant stenosis
of the
P-SMVC
surrounded
Radiology
873
#{149}
Figure isolated
3.
CT scans splenic vein
obtained
with
year-old
man
show CT dilatation in occlusion. (a, b) Scans
5-mm-thick
in a 58(Cy) of the pancreatic tail show a dilated CT (straight arrow in b) and a dilated RGEV (curved solid with
sections
a pseudocyst
arrow in a and b). The RCV (open arrow b) appears normal. St = stomach. Contrast medium is present in the colon and in a small bowel loop.
in
by tumor mass (cancer of the body and tail) or pseudocyst (chronic pancreatitis) was seen on sectional images. Numerous collateral veins
around
the gastric
mesentery
were
fundus
or in the
also
observed. Nine with 10-mmthree scans with
scans were obtained thick sections and 5-mm-thick sections. The CT and RCEV on all CT scans. Their
Table 2 Frequency in Patients
were identified diameters were
greater than 5.0 mm. The veins were interpreted as being dilated. The RCV and MCV were identified on all 5-mmsection scans and could be interpreted as being dilated. The ASPDV, with diameter
less
able
than
2.2
mm,
in 5-mm-section
interpreted
was
scans
as being
GT RGEV RCV MCV ASPDV PSPDV
3;
4, 5).
Figs
Tumor resection was not performed in four patients with pancreatic cancer. In one patient with cancer of the body and tail of the pancreas, invasion to the P-SMVC was
at laparotomy,
while
Note.-Eleven
with chronic by pseudocyst
vein
mesen-
Table 3 Frequency in Patients
complicated were in-
Sectional
imaging
occlusion sis (n
(n
7) or significant
Note-Twelve with chronic
showed
tomy.
served.
were
tamed,
including
raphy sections.
The
scan,
with
CT was
scans
were
a CT arterial
ob-
portog-
10-mm-thick
obliterated
and Mean Diameter Occlusion or Stenosis
Seen on 10-mmSection Scan (n = 9)
Mean
9 9 4 3 0 0
6.7 6.9 5.2 6.5
by a barge
cancer tumor or a pseudoall CT scans. The RCEV was visualized and was dilated in all patients in this subgroup of 11 scans
The
RCV,
MCV,
identifiable
all scans and were ing dilated in most ble4). No
patient
and
in over
with
interpreted of these pancreatic
Surgery
cases
of as be(Ta-
cancer
showed
underwent
tumor extension to the root of the transverse mesocobon in three patients with cancer of the head of the pancreas (Fig 6) and extension of the pseudocyst to the lesser sac through the transverse mesocobon in one patient with pancreatitis.
in
one
patient
with
pancre-
atitis, the RGEV was not identifiable because of the presence of metalic clips used in a previous cyst-gastros-
874
#{149} Radiology
resection.
PSPDV
one-half
pancreatic
In
chronic
5.6(5.2-6.2) 5.2(4.0-5.6) 2.2(2.2) 4.4 NA 1.6
pancreatitis.
Numbers
in paren.
of the CT and Its Tributaries at CT Above the Level of the CT Entry
Diameter (mm)
Seen on 5-mmSection Scan (n = 3)
(5.0-8.8) (5.0-7.8) (4.0-7.8) (4.0-7.8) NA NA
Mean
Diameter
(mm)
3 3 3 3 2 0
7.3(5.3-8.9) 7.9(6.1-11.0) 8.2(5.5-13.7) 8.7(4.7-13.7) 2.1 (2.0-2.2) NA
CT scans were obtained for five patients (four with cancer of the pancreas and pancreatitis). Numbers in parentheses are range of diameters. NA = not applicable.
cyst
(78.6%).
with
Diameter (mm)
one
steno-
= 1) of the P-SMVC. Numerous collateral veins in the mesentery and within the hepatic hibum were ob-
CT
of Visualization with P-SMVC
GT RGEV RCV MCV ASPDV PSPDV
(six with cancer of pancreas and two
cluded.
Fourteen
Mean
5 5 2 I 0 1
5.5 (5.0-8.0) 7.5 (6.2-10.0) 2.0 (2.0) NA NA NA
CT scans were obtained for five patients of diameters. NA = not applicable.
Vein Visualized
or Stenosis the CT
pancreatitis formation) =
Seen on 5-mmSection Scan (n = 5)
Diameter (mm)
at CT
Tributaries
tumor found
splenic
Occlusion including
Eight patients head of the
3 4 2 0 0 0
theses are range
Entry
the
Mean
of the CT and Its
angiograms
showed occlusion of the but a patent portal-superior tenic vein (Fig 4).
Patients with of the P-SMVC
Isolated
Seen on 10-mmSection Scan (n = 6)
Visualized
was
(Table
and Mean Diameter Splenic Occlusion
Visualization
with
Vein
identifi-
and
normal
of
CT Findings in 5-mm-section versus 10-mm-section Scans In patients who tab venous system, 5-mm-section
scans
had a normal porfindings in the were
statistically
superior to those in the 10-mm-section scans regarding depiction of a normal CT (P < .05). There was no statistical
difference
between
5-mm-
and 10-mm-section scans regarding depiction of a normal RCEV or a normal RCV (Table 1). There was also no statistical
difference
between
5-mm-
March
1992
and 10-mm-section scans in depiction of dilated CT, RCEV, RCV, or MCV (Tables 2-4).
CT Findings in Pancreatic versus Pancreatitis
Cancer
There was no statistically significant difference in the rate of occurrence of abnormal CT findings (dilatation and obliteration by mass) in patients with pancreatic cancer and chronic pancreatitis (Table 5).
In 10 patients
with
pancreatic
cer who had an abnormality portal venous system (eight cen of the head of the pancreas two with cancer of the body interpretation of CT findings ysis of the appearance of the its tributaries of occlusion
confirmed or stenosis
volvement) or the vein
of the
splenic
(n
=
8) (which
when
vein
(ii
=
2)
mesenteric could
interpreting
without consideration of the appearance of the CT). In a patient with cancer of the body and tail of the pancreas, the preoperative diagnosis on the basis of findings at CT and angiography was of isolated splenic vein occlusion (resectabbe); however, diagnosis
the presence (tumor in-
portal-superior
pected
can-
of the with canand and tail), by analCT and
be sus-
CT findings
on
the
basis
of the
finding
of
dilatation of the CT, RCV, and MCV could be tumor extension to the P-SMVC (unresectable) (Fig 4). In the remaining nine patients with pancreatic cancer, interpretation ings at CT on the basis
of the of abnormal
find-
dilatation on occlusion of the CT did not result in a change of staging from operable to inoperable with regard to portal venous involvement.
DISCUSSION The CT runs along the anterior pect of the head of the pancreas.
Figure 4. CT scans show GT due to tumor invasion (stenosis) and splenic vein (a, b) Scans obtained with tions in a 59-year-old man
asIt
dilatation of the of the P-SMVC (occlusion). 5-mm-thick sec-
with cancer of the body and tail of the pancreas show dilated GT (large white straight arrow in b). Dilated RGEV (curved solid white arrow in a and
b) and
RCV
(open
white
arrow
in b)
are continuous to GT. The MCV (small white arrows in a and b) is also dilated. ASPDV (black arrow in b) is identifiable.
The Ar-
rowhead in a indicates the gastroduodenal artery. (c) Celiac angiogram depicts occlusion of the splenic vein and dilatation of the RGEV (curved arrows) and the GT (solid black arrow), which drains into SMV (open
arrow). (d) The P-SMVC (arrows), depicted in venous phase of the superior mesenteric arteniogram, was interpreted as normal preoperatively. Demonstration of dilatation of the RCV and MCV at CT (shown in a and b) suggested
a.
b.
Figure 5. CT scans tions in a 25-year-old splenic vein are not
arrow Volume
tumor
extension
to the
P-SMVC.
d.
C.
in a and 182
show CT dilatation in stenosis of the man with chronic pancreatitis show occluded but demonstrate significant
c. P-SMVC a large stenosis
above the CT entry to the SMV. pseudocyst (Cy) occupying almost (straight arrows in a and b). The
CT scans obtained with 10-mm-thick secthe entire pancreas. The P-SMVC and the CT (arrow in c) and the RGEV (curved
b) are dilated.
Number
#{149}
3
Radiology
#{149} 875
drains into the right anterobateral aspect of the SMV after receiving those veins coursing within the transverse mesocobon
(the
MCV),
RCEV,
in addition
RCV,
and
to the ASPDV
(6-
expectation
that
an assessment
.:‘
r,r
9). The transverse mesocobon covers the anterior surface of the head and body of the pancreas and the second part of the duodenum (11-13). An
u
r:;’
of the
CT and its tributaries may lead to a more precise understanding of pathologic conditions of the portal veins or
prompted In patients with
this study. no major abnor-
pancreas
mality
the
of the
normal
portal
(10-mm-thick
thick CT
venous
CT was sections)
sections) scans.
in 48%
to 90%
(5-mm-
on contrast-enhanced
Findings
in our
firmed that the the level of the the head of the
an important
system,
identifiable
study
CT enters uncinate pancreas.
vascular
con-
the SMV at process of This may be
landmark
on
CT scans of the pancreas, representing the root of the transverse mesocobon as it becomes confluent with the root of the small bowel mesentery. The RCEV was also readily recognizable on contrast-enhanced CT scans because of its characteristic hairpin course, running from left to night in the greater omentum near the greater curvature of the stomach. Near the pylorus, the RCEV turns downward
and
backward,
2-6).
forming
Delineation
MCV
RCV
may
depend
on CT scans
amount of the was
on the
fat and the position colon. The ASPDV seen on CT scans even if obtained with thin sec-
were
The
tions.
and
of body transverse rarely
they
the CT (Figs
of the
to section its small
ASPDV
may
misregistration caliber and
because of its oblique or hor-
course.
A CT 5 mm at and was in both scans in
with a diameter greater than CT is considered abnormal identifiable nearly constantly 5-mmand 10-mm-section CT our study. Dilatation of the
represent
occlusive
changes
of the splenic vein or the P-SMVC above the bevel of the CT entry into the SMV. Dilatation of the RCEV (diameter > 5 mm) was always observed in these situations. Hemodynamically, the RCEV may play a role as a collateral pathway in cases of occlusion
of
the
splenic
vein
and
may
also be dilated because of venous gestion that occurs when the CT, SMV (at the CT entry), or P-SMVC occluded. The RCV and MCV are
mal
in patients
occlusion and with occlusion staging
876
of
cancer
#{149} Radiology
with
isolated
conis nor-
splenic
are dilated in patients of the P-SMVC. For of
the
Figure
6.
CT scans show CT obliteration with occlusion of the P-SMVC. Scans were obtained with (a) 10-mm-thick sections and (b) 5-mm-thick sections in a 66-year-old patient with cancer of the head of the pancreas. The P-SMVC and the CT are obliterated by a large tumor mass of
the head
of the pancreas
The RCEV
(M).
(curved
in a) is encased by tumor mass. Dilatation of the white arrows in a and b) are also noted. Extension socolon was found during surgery. a = superior SMV.
Table 4 Frequency
of Visualization with P-SMVC
in Patients
and Mean Diameter Occlusion or Stenosis
Seen on 10-mmSection Scan (n = 7)
Vein Visualized CT RGEV RCV MCV ASPDV PSPDV
Mean
in a) is dilated. arrow to the artery,
The SMV (black
in b) and the MCV root of the transverse Du = duodenum,
arrow
(small mev =
of the CT and Its Tributaries at CT including the Level of the CT Entry
Diameter
(mm)
0 5 4 5 0 5
Note-Fourteen creas and two with plicable.
arrow
RCV (open of cancer mesentenc
Seen on 5-mmSection Scan (n = 7)
NA 7.2 (6.0-10.0) 5.8 (3.3-8.0) 5.0(4.2-7.0) NA 8.8 (7.0-10.0)
Mean
0 6 5 3 0 6
Diameter (mm)
NA 6.6(5.0-10.0) 5.6(4.0-7.8) 5.8(3.0-8.9) NA 9.8(6.0-12.0)
CT scans were obtained for eight patients (six with cancer of the head chronic pancreatitis). Numbers in parentheses are range of diameters.
of the panNA = not ap.
be vulnerable
izontal
CT may
b.
a.
pancreas,
rec-
ognition of dilatation of the RCV MCV at CT may provide the clue
and to
differentiate isolated splenic vein occlusion (resectable) from involvement of the P-SMVC (unresectabbe) in patients with cancer of the body and tail of the pancreas (Fig 4). Similarly, in patients with cancer of the head of the pancreas, the findings of dilatation of the CT and its tributaries at CT may suggest tumor extension to the
P-SMVC
(unresectabbe)
angiograms mab P-SMVC.
or CT
Dilatation
of the
even scans
PSPDV
when
show
a nor-
has been
demonstrated at CT in patients with occlusion of other pancreatico-duodenal veins (4). Likewise, occlusion of the posterior pancreatico-duodenal veins can cause dilatation of the ASPDV and the CT. Portal hypertension may be one of the causes for dibatation of the CT. The CT can also be dilated as a collateral pathway
through tients
the with
RCV localized
or the
MCV
occlusion
in paof the
SMV below the level of the CT entry. Unfortunately, no such case was seen in the limited number of patients reviewed in our study. Obliteration of the CT by a large tumor mass or pseudocyst in the head of the pancreas was an indicator of anterior extension of disease to the root of the transverse mesocobon. The association of occlusion of the SMV and the P-SMVC may be the result of their close anatomic relationship with the CT. Dilatation of the RCEV was also associated with this finding, presumabby as a result of venous congestion. The RCV and/or MCV can also be dilated. Tumor extension can be anatomically localized in the SMV at the CT entry, not reaching the P-SMVC. The CT finding of obliteration of the CT by tumor mass may also help confirm inoperability of March
1992
4. !
Table 5 CT Findings
at CT in Patients
with
Pancreatic
Patients
with
Pancreatic
Chronic
I
Normal
(n
visualization
32)
=
Comparison
Pancreatitis (n = 32)
8
9
20
4
6
21
Abnormal Obliteration
9 9
11 5
0 0
dilatation by mass
5.
Group (n = 41)
Not identified
H, Miyake posterior
H, Aikawa H, et al. superior pancreaticoduode-
nal vein: recognition
Croup
Patients
with Cancer CT Finding
and in Comparison
Diseases
Mon lated
6.
7.
Di-
with CT and clinical
significance in patients with pancreaticobiliary carcinomas. Radiology 1991; 181 :793800. Falconer CWA, Griffiths E. The anatomy of the blood vessels in the region of the pancreas. BrJ Surg 1950; 37:334-344.
Douglass BE, Baggenstoss AH, Hollinshead WH. The anatomy of the portal vein and its tributaries. Surg Gynecol 91:562-576. Reichardt W, Cameron R.
Obstet
1950;
Anatomy
of the
pancreatic veins: a postmortem and clinical phlebographic investigation. Acta Radiol CT
t;T
KCEV
: Figure
4sI.t.t.
kGV
: 7.
Flow
:
chart
CT and major portal ment with pancreatic
depicts
venous cancer.
1d
system,
CT findings
branch
diseases. Recognition of abnormalities of the CT on CT scans may improve the accuracy of staging of cancer of the pancreas by clarifying the degree of involvement of the portal venous
d*I.t.t&
involve-
for
as well
identification the transverse
as by
assisting
Volume
182
#{149} Number
3
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Acknowledgments: We thank Monika Femer for preparation of this manuscript and Hiroyuki Shimamoto, MD, for his assistance with statisti-
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