Retroperitoneum

Question 1

Imaging techniques

Answer 1

CT
MRI
US
Plain films (have limited role)

Question 2

The anterior and posterior renal fascia divide the retroperitoneum into three compartments:

Answer 2

The anterior pararenal space (pancreas and duodenum A&D colon)
The perinephric space (kidneys and adrenal glands)
The posterior pararenal space (fat)

Question 3

DDs of retroperitoneal mass

Answer 3

•Nodal (lymphoma, germ cell tumor, or metastasis)
•Retroperitoneal fibrosis
•Neurogenic (paraganglioma, schwannoma, ganglioneuroma)
•soft tissue sarcoma (liposarcoma, fibrosarcoma)
•hematoma(following interventional procedure, trauma, or ruptured aortic aneurysm)
•Infection (psoas abscess, retroperitoneal abscess)
•Vascular (aneurysm)

Question 4

DDs of retroperitoneal masses (review)

Answer 4

1. aneurysm
2. hematoma
3. tumor (lymphoma, soft tissue sarcoma, neurogenic tumors like shwannoma)
4. infection (psoas abscess)

Question 5

retroperitoneal compartments (review)

Answer 5

1. anterior pararenal
2. perinephric
3. posterior pararenal

Question 6

causes of aortic aneurysm

Answer 6

1. atherosclerosis
2. inflammation
3. aortic dissection
4. marfan and Ehlers danlos syndrome

Question 7

aortic aneurysm more common in male or female?

Answer 7

male (4 times)

Question 8

normal size of aorta

Answer 8

<3
if >5 surgery is required

Question 9

How does aoritc aneurysm appear on plain radiograph

Answer 9

Area of curvilinear calcifications in the paravertebral region

Question 10

Gold standard for evaluation of aortic aneurysm

Answer 10

CT angiography (CTA):
Excellent for preoperative plaining

Question 11

complication of aortic aneurysm and how it appears by CT

Answer 11

rupture –> contrast extravasation

Question 12

causes of retroperitoneal hematoma

Answer 12

1. trauma
2. surgery
3. Rupture of aneurysm
4. Rarely spontaneous retroperitoneal hemorrhage (SRH)

Question 13

Signs of lank rupture (AAA) on CT angiography include:

Answer 13

Retroperitoneal hematoma
Para-aortic fat stranding
Contrast extravasation

Question 14

special sign of aortic aneurysm

Answer 14

The “yin yang sign ” or Pepsi sign by doppler

Question 15

Psoas abscess

Answer 15

Collection of pus located in the iliopsoas muscle compartment

Question 16

incidence of psoas abscess

Answer 16

M>F 44-60
Younger? (Immunosippression kf IV drug)

Question 17

Clinical presentation of psoas abscess;

Answer 17

Triad: fever, limp(not limb), and back pain.
Inguinal mass, anorexia, weight loss
Can present with septic shock

Question 18

Cuases of psoas abscess

Answer 18

• 1ry: DM, IV drug use, AIDS, RF, Immmunosuppression
• 2ry: Ca bowel or any bowel inflammatory process, TB, vertebral osteomyelitis, or renal abscess

Question 19

Modality of choice for psoas abscess detection

Answer 19

CT

Question 20

Psoas abscess on AXR

Answer 20

• Not visualized psoas muscle shadow
Large radiopacity seen in lumbar region

Question 21

Psoas abscess on CT

Answer 21

Large bilobed peripherally enhanced collection

Question 22

So.. what are the three modalities for psoas abscess

Answer 22

• MRI: You can use to diagnose and rule out other causes of back pain
• CT
• AXR