brief and concise on radiological anatomy of retroperitoneum includes topic like pararenal space,perirenal space,fascial plane,retroperitoneum hematoma and sign of mass origin

1. RADIOLOGICAL ANATOMY OF
RETROPERITONEUM
DR.KAMAL ADHIKARI
RADIOLOGY 1ST YEAR RESIDENT

2. • Retroperitoneum
• Pararenal spaces
• Perirenal spaces
• Interfascial planes
• Retroperitoneal hematoma
• Retroperitoneal mass
• Identification of organ of origin

3. Retroperitoneum
• The retroperitoneum is the part of the abdominal cavity that lies
between the posterior parietal peritoneum and anterior to the
transversalis fascia.
• It is divided into three spaces by the perirenal fascia (Fascia's of
Gerota and Zukerkandl) and is best visualized using CT or MRI .The
Three spaces are:
– anterior pararenal space
– perirenal space
– posterior pararenal space

6. BOUNDARIES OF RETROPERITINEUM
Retroperitoneum is bounded
• anteriorly by the posterior parietal peritoneum,
• posteriorly by the transversalis fascia
• extends craniocaudally from the diaphragm to the pelvic brim.

7. INTRAPERITONEAL AND RETROPERITONEAL
ORGAN
Major Intraperitoneal Organ Secondary Retroperitoneal Organ Primary Retroperitoneal Organ
Stomach Duodenum 2nd and3rdpart Kidney
Liver and gall bladder Pancreas: head,neck and body Adrenal gland
spleen Ascending and descending colon Ureter
Duodenum 1st part Upper rectum Aorta
Tail of pancreas Inferior venacava
Jejunum , ileum, appendix Lower rectum
Transverse and sigmoid colon Anal canal

8. Anterior Pararenal Space
Boundaries
– Anteriorly: post parietal peritoneum
– Posteriorly: ARF[anterior renal fascia]
– Contents: Ascending and descending colon, duodenum, pancreas
– Continuous across midline, with root of small bowel mesentery and
inferiorly with perirenal, posterior pararenal and prevesical spaces

10. Posterior Para renal Space
Boundaries
– Anteriorly: PRF[posterior renal fascia] and lateral conal fascia.
– Posteriorly: transversalis fascia.
– Open laterally to flank and inferiorly to pelvis
– Contents: Fat (no visceral organs)

11. Posterior Para renal Space
• Continues anterolaterally into the properitoneal fat,the
extraperitoneal fat of the anterior abdominal wall.

13. Peri Renal Space
Boundaries
• Superior - open to bare area of liver and contiguous with
mediastinum.
• Medial – anterior and posterior renal fascia fuse
• Lateral - ARF, PRF fuse to form lateroconal fascia
• Inferior - ARF & PRF converge blend about 8 cm below kidney

16. Contents of Perirenal Space
• Kidney, proximal collecting system, adrenal gland,
• Renal vasculature
• Lymphatics
• Bridging septa

18. Iliopsoas compartment
Iliopsoas compartment:
- located within and immediate adjacent to psoas muscle
- posteromedial to the posterior pararenal space

20. Interfascial Plane
These interfascial planes are represented by
- Retromesenteric
- Retrorenal
- Lateroconal interfascial plane,
- Combined interfascial planes

22. • The retromesenteric, retrorenal, and lateroconal planes are potential
routes of interfascial communication between the retroperitoneal
spaces.
• Retroperitoneal hemorrhage or rapidly expanding fluid collections can
spread via these interfascial connections.

23. • Retro mesenteric - between anterior pararenal and perinephric
spaces contiguous across midline and laterally with retro renal and
lateral conal space.
• Retro renal - between perinephric and posterior pararenal spaces·
• Lateral conal
– Combined fascial plane continues into pelvis anterolateral to psoas
muscle.
– Allowing pathway to pelvis.
– Trifurcation of 3 planes - anterioposterior location is variable

25. The Retromesenteric plane
• Expansile plane located between the anterior pararenal space and
perirenal space

26. The Retrorenal plane
Between the perirenal space and posterior pararenal space

27. The lateroconal interfascial plane
Between layers of the LCF[lateroconal fascia]. It communicates with
the RMP[retromesenteric plane] and RRP[retrorenal plane] at the fascial
trifurcation.

28. • formed by the inferior blending
of the RMP[retro mesenteric
plane] and RRP[retrorenal plane]
. It continues into the pelvis.
The combined interfascial plane

29. The fascial trifurcation
• The point at which the RMP[retromesenteric plane], RRP[retrorenal
plane], and LCF[lateroconal fascia] planes communicate mutually

30. Interfascial Plane Extensions

31. Medial Extension
• RMPs and RRS are continuous across the
midline

32. Right superior extension

33. Left superior extension
• The RMP ,RRP and PRS on the left extend to the left hemidiaphragm

34. Retroperitoneal hematoma

35. Anatomic Zones of Retroperitoneum
ZONES VASCULAR CONTENTS VISCERAL CONTENTS
I[midline
Retroperitoneum]
Supramesocolic suprarenal abdominal aorta pancreas
celiac axis duodenum
proximal superior mesenteric artery
superior mesenteric vein
proximal renal arteries
Inframesocolic infrarenal abdominal aorta
infrahepatic IVC

36. ZONES VASCULAR CONTENTS VISCERAL CONTENTS
II[Upper lateral renal arteries kidneys,adrenal glands
Retroperitoneum] renal veins renal pelvis,proximal
ureter
III[Pelvic retro- iliac arteries,
Peritoneum] iliac veins

37. Zone I
Mandates exploration for both penetrating and blunt injury because of the
high likelihood of major vascular injury in this area.
Zone II
Injury to the renal vessels or parenchyma and mandates exploration for
penetrating trauma.
A nonexpanding stable hematoma resulting from a blunt trauma mechanism
is better left unexplored.
Zone III
• Penetrating trauma mandates exploration
• Blunt trauma are usually with pelvic fractures management is based
external fixation or angiographic embolization

38. Goals of Imaging in Retroperitoneal
Hemorrhage
• To identify the retroperitoneal hemorrhage, it’s location and possible
source
• To assess its relative stability on the basis of the size and presence [or
absence] of active extravasation of intravascular contrast material

39. Retroperitoneal hemorrhages & fluid
collections
• Below the kidneys, the retroperitoneal spaces- a single space with
direct contiguity between the anterior and posterior portions.
• Retroperitoneal hemorrhage or fluid spread from the abdominal
retroperitoneum into the extraperitoneal pelvis along the anterior
and posterior perirenal fasciae, which combine to form the fascial
plane in the iliac fossa.

40. • Superiorly , the perirenal fasciae are attached to the diaphragm.
• On the right side, the bare area of the liver is directly connected to
the anterior pararenal space.
Therefore , hepatic lacerations involving the bare area of the liver can
be a source of retroperitoneal hemorrhage.

41. Retroperitoneal masses

44. Identification of the Organ of Origin
• Some radiologic signs that are helpful in determining tumor origin
include
– the “beak sign,”
– the “phantom (invisible) organ sign,”
– the “embedded organ sign,” and
– the “prominent feeding artery sign”

45. Beak sign
• When a mass deforms the edge of an adjacent organ into a “beak”
shape, it is likely that the mass arises from that organ (beak sign).
• On the other hand, an adjacent organ with dull edges suggests that
the tumor compresses the organ but does not arise from it

46. Phantom (Invisible) Organ Sign
• When a large mass arises from a small organ, the organ sometimes
becomes undetectable. This is known as the phantom organ sign.
• However, false-positive findings do exist, as in cases of huge
retroperitoneal sarcomas that involve other small organs such as the
adrenal gland.

47. Embedded Organ Sign
• When a tumor compresses an adjacent plastic organ (eg,
gastrointestinal tract, inferior vena cava) that is not the organ of origin,
the organ is deformed into a crescent shape.
• In contrast, when part of an organ appears to be embedded in the
tumor , the tumor is in close contact with the organ and the contact
surface is typically sclerotic with desmoplastic reaction.
• When the embedded organ sign is present, it is likely that the tumor
originates from the involved organ.

49. Prominent Feeding Artery Sign
• Hypervascular masses are often supplied by feeding arteries that are
prominent enough to be visualized at CT or MR imaging, a finding that
provides an important key to understanding the origin of the mass.

50. “CT angiogram sign” or “floating aorta sign”
• Retroperitoneal masses arising posterior to the aorta can insinuate
between the aorta and the vertebral column and displace the aorta
anteriorly; and hence the term floating aorta sign.

52. references
• Haaga CT & MRI of whole body 5th edition
• Ryan anatomy
• Radiopaedia