Imaging of the spleen and immune system

Question 1

The spleen

Answer 1

• Wedge shaped
• Protected by ribs 9-11
• Diaphragmatic and visceral surfaces
• Covered in peritoneum except at hilum which forms gastrosplenic (spleen to stomach, contains arteries) and splenorenal ligaments (splenic artery and pancreatic tail, connects spleen to left kidney)

Question 2

Common causes of splenomegaly

Answer 2

Thalassaemia
EB virus
Cirrhosis
Portal hypertension

Question 3

Splenic injury grading system

Answer 3

• Splenic injury grading system from 1 to 5
• Grade 1= subcapsular haematoma, grad 5 = shattered spleen, bleeding into peritoneum
• Splenic infarct as a result of ischaemia - arterial supply is interrupted
• Normally splenic infarct is wedge shaped

Question 4

Blood supply to spleen

Answer 4

• Arises from coeliac axis - first major branch at T11/12
• Coeliac axis forms common hepatic artery, left gastric artery and splenic artery
• Splenic artery is one of the terminal branches of coeliac trunk and travels towards splenic hilum, runs in splenorenal ligament
• Splenic artery divides into superior and inferior terminal branches

Question 5

Splenic vein

Answer 5

• Splenic tributaries emerge at the splenic hilum
• Runs in splenorenal ligament with splenic artery
• Behind pancreas, it confluences with SMV to form portal vein

Question 6

How to scan LNs

Answer 6

Evaluation of LNs:

• CXR
• US
• CT - large areas in one go
• MR - nodal appearance
• PET - shows metastases
• Tissue sampling - biopsy etc
• We want LNs to be bean shaped and not round

Question 7

Lymphoma staging

Answer 7

• Ann Arbor: classification for Hodgkin and non-hodgkin lymphoma
• Updated to LUGANO classification
• Stage 1: 1 nodal group/lymphoid organ on same side of diaphjragm
• Stage 2: more than 2 anatomic regions and nodal groups on same side of diaphragm
• Stage 3: both sides of diaphragm, not extending beyond nodes, spleen (3s = spleen)
• Stage 4: extralymphatic organ environment