retroperitoneo anatomía
DESCRIPTION
articulo de anatomía del retroperitoneo en cortes seccionalesTRANSCRIPT
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Correlative anatomy and
computed tomography:
A module on the pancreas and posterior
abdominal wall
Carl J. Zylak, M.D.
w. Pallie, MB.
An appreciation of the retroperitoneum stems from an under-
standing ofits layered nature.
Several texts have appeared which seek to correlate computed tomo- Introduction
graphic images with cross-sectional human anatomy. In general, they relate
CT scans to cadaveric anatomy as represented by various old anatomic at-
lases. Accordingly, they are of limited value in the interpretation of living
anatomy as recorded by clinical computed tomography. To facilitate the
interpretation of CT scans, this exhibit presents the following:
1 . Schematic drawings illustrating the basic morphologic concept of
the layered retroperitoneum.
2. Normal CT images with interpretation of the anatomy.
3. Abnormal CT images with interpretation of the pathology.
An appreciation of the retroperitoneum stems from an understanding
of its layered nature. Considered from posterior to anterior, one may
distinguish:
1 . A musculoaponeurotic plane, embracing the quadratus lumborum
and psoas muscles, the diaphragmatic crura and associated liga-
mentous fascia.
2. The posterior pararenal space, which continues anteriorly into the
properitoneal fat, the extraperitoneal fat of the anterior abdominal
wall.
3. The perirenal space which is contained by the renal fascias.
4. The anterior pararenal space which is limited anteriorly by the
posterior peritoneum, and which is continuous across the midline.
It lies immediately anterior to the perirenal space.
From the Departments of Radiology and Anatomy, McMaster University and Medical
Centre, Hamilton, Ontario.
Volume 1, Number 1 May 1981 RadioGraphics 61
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FASCIA TRANSVERSAHS
ontenor (A
middle M) ] Laminaeposter or
Zylak, Pallie
62 RadioGraphics May 1981 Volume 1, Number 1
Correlative Anatomy and Computed Tomography
Normal anatomy, posterior abdominal wall:
LIGAMENTS AND MUSCLES
Figure lACoronal schematic. Heavy black
lines indicate the median arcuate
ligament across the crura of the
diaphragm (dotted lines), the
medial arcuate ligament over the
psoas muscle, and the lateral arcu-
ate ligament over the quadratus
lumborum muscle.
Figure lB
Cross-sectional schematic demon-
strating the fascial relationships of
the right and left crura of the dia-
phragm, the psoas muscle, the
quadratus lumborum muscle and
the sacrospinalis muscle.
B
(P
FAT
Key: #{174}= aorta; Ab-R rectus aixlominis muscle; ALL anterior longitudinal ligament;CRL = left diaphragmatic crus; CRR right diaphragmatic crus; EO external oblique
muscle; 10 = internal oblique muscle; MLD latissimus dorsi muscle; MSPI serratus
posterior inferior muscle; Ps psoas muscle; QL quadratus lumborum muscle; SSp sa-
crospinalis muscle; TD thoracic duct; TR transverse abdominis muscle; VA azygos
vein.
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B
Volume 1, Number 1 May 1981 RadioGraphics 63
Zylak, PallieCorrelative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
KIDNEYS
Figure 2A
Coronal schematic showing position of
kidneys, adrenals and the aorta relative
to the muscles and ligaments of the pos-
tenor abdominal wall.
Figure 2BCross-sectional schematic showing the
perirenal fat (stippled) enclosed by the
anterior and posterior layers of renal
fascia. The posterior renal fat (hatched)
is continuous laterally with the flank fat
and the extraperitoneal fat of the ab-
dominal wall. The transversalis fascia
(black line) lies external to the extra
peritoneal fat.
Figure 2C
Coronal schematic. The renal fascia
blends with the adjacent fascias in all
directions.
Figure 2D
Parasagittal schematic showing the re-
lationships of the perirenal (stippled) and
posterior pararenal (hatched) spaces.
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A
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Zylak, Pallie
RadioGraphics May 1981 Volume 1, Number 164
Correlative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
INFERIOR VENA CAVA, RENAL VEINS, KIDNEYS, URETERS
Figure 3A
Coronal schematic with the inferior vena
cava, the renal veins and the ureters
added.
Figure 3B
Cross-sectional schematic. The perirenal fat
(stippled) is enclosed by the anterior and
posterior layers of the renal fascia both of
which lie anterior to the posterior pararenal
space (hatched). In the midline region, the
aorta, the inferior vena cava and the hilar
structures of the kidneys with their sur-
rounding fascias effectively shut off the
perirenal spaces.
Figure 3C
A radiograph of a cadaver cross section
showing the conspicuous fat in the perirenal
space and its delimitation by fascial tissue
in the midline area.
B
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A
B
Volume 1, Number 1 May 1981 RadioGraphics 65
Zylak, PallieCorrelative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
VASCULAR RELATIONSHIPS
Key: A = aorta; IMV = inferior mesenteric vein; IVC= inferior vena cava; PV = portal vein; RV(L) = leftrenal vein; SA = splenic artery; SMA = superiormesenteric artery; SMV = superior mesenteric vein;
SV = splenic vein.
Figure 4A
Coronal schematic of the retroper-
itoneum showing vascular rela-
tionships as well as the position of
the spleen. The inferior mesenteric
vein joins the splenic vein which in
turn is joined by the superior mes-
enteric vein to form the portal vein
which crosses to the right. The left
renal vein lies posterior to the su-
perior mesenteric vessels; the
splenic vein crosses anterior to the
superior mesenteric artery.
Figure 4B
Cross-sectional schematic
again demonstrating vascular
relationships. The portal vein
lies anterior to the plane of the
aorta and the vena cava.
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C D
Zylak, Pallie
66 RadioGraphics May 1981 Volume 1, Number 1
Correlative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
DUODENUM, PANCREAS
Figure 5ACoronal schematic showing the relation-
ships of the duodenum and pancreas. The
uncinate process of the pancreas hooks
behind the superior mesenteric vessels
which lie anterior to the horizontal (third)
portion of the duodenum. The hepatic
artery is shown above the duodenum.
Figure 5B
Cross-sectional schematic. The anterior
pararenal compartment (stippled) contains
the pancreas, duodenum and, imbedded
posteriorly, the aorta, inferior vena cava,
duodenojejunal flexure and the ascending
and descending colon. On each side, ex-
tensions of this space in the flanks, merge
with the extraperitoneal fat layers.
Figure 5C
Parasaggital schematic showing the rela-
tionship of the three spaces: the anterior
pararenal (stippled), the perirenal (finely
stippled), and the posterior pararenal
(hatched). (1)
Figure 5D
Saggital section demonstrating peripan-
creatic (anterior pararenal compartment)
spaces connecting with the mesenteries of
the transverse colon and the small
bowel.
Key: A = aorta; C colon; CA ascending colon;CD = descending colon; CT transverse colon; D
= duodenum; D2 second portion of duodenum;
HA = hepatic artery; IVC inferior vena cava; J= Jejunum; KL = left kidney; KR = right kidney;
P = pancreas; St = stomach.
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SUBEOSTAL PLANE
Volume 1, Number 1 May 1981 RadioGraphics 67
Zylak, PallieCorrelative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
PANCREATIC TOPOGRAPHY
Figure 6
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PANCREATIC MEASUREMENTS, VARIATIONS IN POSITION
PM CT SCAN ULTRASOUND
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Normal anatomy, retroperitoneum:
A
Zylak, Pallie
RadioGraphics May 1981 Volume 1, Number 1
Figure 7
Sagittal, coronal and cross-
sectional schematic dem-
onstrating the relationships,
positional variation and
measurements of the pan-
creas.
Correlative Anatomy and Computed Tomography
Normal anatomy, retroperitoneum:
Figure 8A
Schematic representa-
tion of the anatomic re-
lationships of structures
about the biliary and
pancreatic ducts.
Figure 8B
Endoscopic retrograde
choledochopancreato -
gram
illustrating relationships
shown in Figure 8A.
Key: D2 = second portion of
duodenum; GB = gallbladder;HA = hepatic artery; Pd =
pancreatic duct; PV = portalvein.
68
STRUCTURES RELATED TO DUCTS
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SUBCOSTAL PLANE (L3) PLANE OF L2 (INFERIOR)
Key: A = aorta; CA = ascending colon; CD descending colon; DII second portion of
duodenum; GB - gallbladder; IVC inferior vena cava; K(R) & K(L) right and left kidneys;PS = psoas muscle; SMA = superior mesenteric artery; SMV superior mesenteric vein; UP
= uncinate process of pancreas.
Volume 1, Number 1 May 1981 RadioGraphics 69
Zylak, Pallie
Correlative Anatomy and Computed Tomography
Normal cross-sectional (CT) anatomy:
B
Figures 9A & B
This scan lies caudad to the pancreas, cutting
through the plane of the horizontal (third)
portion of the duodenum. Posteriorly lie the
aorta, inferior vena cava, kidneys and ureters,
in the perirenal space. Anteriorly lie the su-
perior mesenteric vessels (not identified), the
jejunum and transverse colon. The ascending
and descending portions of the colon flank the
inferior poles of the kidneys
B
Figures 1OA & B
This scan lies immediately cephalad to the
subcostal plane (L2). The uncinate process of
the pancreas is defined in the midline by the
superior mesenteric vessels anteriorly and the
aorta posteriorly. Anterior to these lie the
transverse colon (in the midline), the liver and
gallbladder (on the right), and loops of opaci-
fied small bowel (on the left).
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PLANE OF L2 (SUPERIOR) TRANSPYLORIC PLANE (Li.)
Figures hA & B
B
Key (pages 70 and 71): A aorta; B body of pancreas; C colon; CRR right crus of di-
aphragm; D duodenum; Dl first portion of duodenum; D2 second portion of duo-
(lenum; GB = gallbladder; H head of pancreas; IVC inferior vena cava; J jejunum;
Zylak, Pallie
70 RadioGraphics May 1981 Volume 1, Number 1
Correlative Anatomy and Computed Tomography
Normal cross-sectional (CT) anatomy:
B
Scan at the level of L2. Two veins, the left renal
and splenic, cross the midline separated by the
superior mesenteric vessels. Anterior to the
right kidney lies the duodenum, the head of
the pancreas, the inferior vena cava, and the
right crus of the diaphragm.
Figures 12A & B
Scan through transverse pyloric plane (L12).
The head of the pancreas is shown in relation
to the duodenum. The pancreas continues to
cross the midline anterior to the aorta and su-
perior mesenteric vessels. The left hypochon-
drium contains loops of jejunum, splenic
flexure and the lower end of the spleen.
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PLANE OF Li (INFERIOR) PLANE OF Li (SUPERIOR)
LCF = splenic flexure; LO lesser omentum; L(R) right lobe of liver; L(RL) right and
left lobes of liver; RK & L(K) right and left kidneys; RVL left renal vein; S or St
stomach; SM superior mesenteric vessels; Sp spleen; SV splenic vein; T tail of pan-
creas; TO = tuber omentale of pancreas.
Volume 1, Number 1 May 1981 RadioGraphics 71
Zylak, Pallie
Correlative Anatomy and Computed Tomography
Normal cross-sectional (CT) anatomy:
Figures 13A & B
The neck of the pancreas crosses the superior
mesenteric vessels in the midline. The body of
the pancreas is related to the stmoach anteri-
orly with the lesser sac interposed between
them. Jejunum and omental fat occupy the left
hypochondrium.
Figures 14A & B
This scan cuts the lesser curvature of the
stomach (upper L1). The lesser omentum abuts
on the tuber omentale of the body of the pan-
creas. The pancreas is well defined by pen-
pancreatic fat and the tail of the pancreas
points to the splenic hilum.
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Zylak, Pallie
Correlative Anatomy and Computed Tomography
Pathology, anterior pararenal space:
CALCIFIC PANCREATITIS
Figures i5A & B
A survey radiograph (A) illustrates pancreatic calcifi-
cation and topography for comparison with CT scans
of the same patient. In the scans which have been made
at successively higher (more cranial) levels, note the
anatomic relationships of the pancreas. The head lies medial to the second portion of the duodenum (B).
The pancreas is opacified by calcifications.
PSEUDOCYSTS OF PANCREAS
L I
A pseudocyst in the head of the pancreas is identified by endoscopic retrograde choledochopancreatography
(A). On the most caudal CT scan (B) the same cyst is indicated by an arrow.
72 RadioGraphics May 1981 Volume 1, Number 1
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Correlative Anatomy and Computed Tomography
The neck and body lie anterior to the superior mesentenic artery (arrow) (C). The stomach lies anterior
to the pancreas. The tail of the pancreas abuts on the splenic hilum (D).
Figures 16C & DCT scans of the same patient exposed at higher levels (C and D) demonstrate additional cysts (arrows)
in the body and tail of the pancreas.
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Zylak, Pallie
Correlative Anatomy and Computed Tomography
Pathology, anterior pararenal space:
PHLEGMONOUS PANCREATITIS
The inferior aspect of the right perirenal space containing fat (arrows) is recorded in scan A. At the same
level, an inflammatory mass (M) is seen surrounding the right renal cone laterally and anteriorly. In a
more cranial scan (B) the right kidney and penirenal fat appear normal, indicating no involvement of the
penirenal space.
Figures 18A & B
A survey radiograph (A) shows the stomach to be displaced infeniorly and laterally by a large mass. On
the most caudal of the CT scans (B) fluid is evident medial to the liver (arrows) with a much larger collection
(C) medial to this, located in the lesser omentum. The pancreatic head is probably enlarged with loss ofpenipancreatic fat planes.
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Figures i7C & D
At a yet higher level (C) the inflammatory mass (M) is seen to extend across the midline and to distend
the anterior pararenal space. Dot like opacities adjacent to the lateral margin of the stomach in scan D,
are vessels which may represent varices.
Zylak, Pallie
Correlative Anatomy and Computed Tomography
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Zylak, Pallie
Correlative Anatomy and Computed Tomography
Pathology, anterior pararenal space:AORTIC ANEU
Figure l9A Figure i9B
The most caudal scan of this patient, demonstrates In a more cranial section, the aneurysm is readily ap-
calcification in the aorta (A) which is only slightly di- parent. The lucent crescent represents thrombus.
lated.
LYMPHOMA
Figures 20A & B
In CT scan A, large nodal masses (M) displace the aorta (cursor) to the right and obliterate the paravascular
fat planes. In a more cranial scan (B) a large right retrocrural lymph node (arrow) displaces the crus.
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Correlative Anatomy and Computed Tomography
Figure i9C Figure i9D
In a yet more cranial scan, the aneurysm is seen to At the level of the superior mesentenic artery (arrow),
bulge from the right side of the aorta which contains the aneurysm is no longer evident.
calcification. Renal cysts are present on the left.
Pathology, perirenal Space:
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Multiple CT scans representing successively more cranial planes show the penirenal space on the left to
be distended by an inflammatory process, which obliterates the penirenal fat and thickens the renal fascia.
The posterior paranenal and extrapenitoneal fat planes are preserved (arrow).
URINOMA
I_c,____
A delayed radiograph from the excretory urogram of
a 70-year-old male with carcinoma of the bladder
shows penirenal extravasation of contrast material
(arrow).
CT scan at the level of the lower pole of the left kidney
shows a fluid (F) collection in the penirenal space
medially. The renal fascia is clearly delineated (ar-
rows).
Zylak, Pallie
78 RadioGraphics May 1981 Volume 1, Number 1
Correlative Anatomy and Computed Tomography
Pathology, perirenal Space:
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)
A more cranial scan through the plane of the renal The scan shows fluid (F) occupying the penirenal space
pelvis shows loculated fluid (F) in the medial and cranial to the left kidney. This may account for the low
posterior parts of the penirenal space displacing the position of the left kidney in this case.
kidney anterolaterally. The compartmentalization
medially is well defined (arrow).
Volume 1, Number 1 May 1981 RadioGraphics 79
Zylak, PallieCorrelative Anatomy and Computed Tomography
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In the scan, fluid (F) is present in the right posterior In a scan cranial to the right kidney, craniad extension
pararenal space. This represents blood from a leaking of blood (F) in the posterior pararenal space is dem-
aortic aneurysm. Large bilateral renal cysts are onstrated.
present.
ABSCESS
Figures 25A-D
This series of CT scans shows loculated fluid collections (A) with enhancement of their margins located
in the posterior abdominal wall and encroaching on the left posterior pararenal space. Note that the per-
irenal space and propenitoneal fat plane (arrow) are not involved.
80 RadioGraphics May 1981 Volume 1, Number 1
Zylak, Pallie
Correlative Anatomy and Computed Tomography
Pathology, posterior pararenal space:
LEAKING AORTIC ANEURYSM
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ScanCrepresenting the level of the superior mesentenic artery (arrow) demonstrates fluid (F) in the right
posterior pararenal space. This is shown in more detail in the enlargement (D).
Volume 1, Number 1 May 1981 RadioGraphics 81
Zylak, Pallie
Correlative Anatomy and Computed Tomography
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Zylak, Pallie
Correlative Anatomy and Computed Tomography
Pathology, multiple space involvement:
Figures 26A-D
This series of CT scans demonstrates involvement of the anterior paranenal space with transgression of
the renal fascia on the right. Note the obliteration of penirenal fat anterolaterally on the night as compared
to the left side. Fluid within the anterior pararenal space is shown extending into the right iliac fossa.
In Figures 1 through 8, the positions and relationships of successively
more anterior structures of the retropenitoneum are illustrated with coronal
and cross-sectional schematic drawings. These schematics emphasize the
concept of the layered retropenitoneum and clarify the spatial relations of
structures recorded in CT scans.
Examples of pathologic anatomy as recorded by computed tomography
are interpreted by reference to the normal anatomy of the three spaces of
the retropenitoneum. Pancreatitis serves as the model for understanding the
anterior pararenal space. The confinement of pathology within the penirenal
space by the renal fascia is illustrated by several examples, including that
of a uninoma. The posterior pararenal space is illustrated with clinical scans
demonstrating an abscess and leakage from an aortic aneurysm. Also included
are scans of a patient with pancreatitis, illustrating a pathologic process in-
volving multiple spaces.
SUMMARYThis exhibit has presented an approach to the understanding of the
cross-sectional anatomy of the retnopenitoneum that facilitates the task of
interpreting normal and pathologic CT scans. The normal appearance of
the individual compartments of the retroperitoneum and the appearance
of pathologic processes involving them, both individually and in combination,
have been demonstrated. Clinical CT scans illustrating the findings in
82 RadioGraphics May 1981 Volume 1, Number 1
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Correlative Anatomy and Computed Tomography
pancreatitis, urinoma and renal abscess, adrenal tumor, aortic aneurysm,
and lymphoma have been presented.
1. Meyers MA: Dynamic Radiology of the Abdomen. New York, Springer-Verlag, Berlin, ReferencesHeidelburg, 1976, pp 113-190
2. DeGraaff CS, Taylor KJW, Simonds BD, Rosenfield AT: Gray-scale ecography of the
pancreas: re-evaluation of normal size. Radiology 129:157-161, 19783. Kreel L: Computerized tomography of the pancreas. Computed Axial Tomography 1:
287-297, 1977
ACKNOWLEDGMENTS
Mrs. Deborah Miller for the excellent art work, the Audiovisual Depart-
ment, McMaster University and Mrs. L. MacRae for typing the manu-
script.
Volume 1, Number 1 May 1981 RadioGraphics 83