The spleen is located in the left upper quadrant of the abdomen. It filters blood and fights infections. The spleen develops from embryonic tissue and is supplied by the splenic artery and drained by the splenic vein. It can vary in size and shape. Accessory spleens are common. Injuries from trauma are most often seen in the spleen. Conditions like infections, cancers, blood disorders can cause abnormalities. Imaging with ultrasound, CT scan, MRI and nuclear medicine scans are used to evaluate the spleen.

1. SPLEEN
-By Ankit Beniwal

2. ANATOMY
• Spleen is the largest organ of lymphatic system in
human body.
• Origin:The spleen develops in the cephalic part of
dorsal mesogastrium (from its left layer; during
the sixth week of intrauterine life) into a number
of nodules that fuse and form a lobulated spleen.
• Location: Lies along the axis of 10th rib.
• Size: normally varies from 7 to 12 cm.
• Formula to assess the size according to age is:
• Weight: 150 to 200grams normally

3. • Blood supply and venous drainage:
Arterial supply: Splenic artery which is tortous and is
the largest branch of celiac trunk. Divides into multiple
branches just before it enters the hilum of spleen.
Venous drainage: Splenic vein which originates from
splenic hilum joins superior mesentric vein to form
portal vein behind the neck of pancreas.
• Ligaments:
1. Gastro-splenic .(spleen enlarges in it’s direction)
2. Spleno-renal.
3. Spleno-phrenic.
4. Spleno-colic.
• Nerve supply: Sympathetic fibers of celiac plexus

5. ANATOMICAL VARIATION
1. Accessory spleen or splenunculi:
• Not uncommon and found in 10-30% of the population.
• Mostly lie along the spleen itself(most common site), tail of
pancreas, along splenic artery, at hilum of spleen or in
omental ligament.
• They may enlarge after splencetomy.
• X-ray: It may appear as mass indenting stomach.
• USG: Appears a solid mass which is isoechoic to the spleen.
• CT scan: They have density and enhancing characteristics
similar to the rest of the spleen
• Splenic scintigraphy: It is the investigation of choice to locate
normal functioning splenic tissue. (Explained further on)

6. Splenunculi abutting the tail of
pancreas

7. 2. Polysplenia:
• They are multiple splenic masses seen along
normal spleen or without a normal appearing
spleen.
• They may vary from 2 to 16 in number.
• Present on patient’s left side but may be present
bilaterally.
• Associated with other anomalies too, eg:
Congenital heart disease, gut malrotation, IVC
anomalies, portal anomalies etc.

9. 3. Splenosis:
• When a normal spleen is auto-transplanted or
moved away from it’s usual location due to
any trauma to abdomen.

11. 4. Asplenia: Two types-
(i) Anatomical asplenia: Absence of spleen
congenitally or iatrogenic.
(ii) Functional asplenia: A spleen is seen but it is
non functional.
• Splenic fossa appears empty in anatomical
asplenia.
• In case of functional asplenia normal functional
tissue can not be traced on splenic scintigrapghy.

12. SPLENIC TRAUMA
• Spleen is the most common organ to be injured in
blunt trauma to the abdomen.
• Accounts for 40% of all solid organ injuries.
• Incidence of penetrating trauma of spleen is
relatively low due to low surface area of spleen,
which is approx 7% of abdominal surface.
• X-ray: May show a mass in left hypocondrium
with or without presence of single or multiple rib
fractures. Not of much use though.

13. • USG: It has become a first line investigation for
any abdominal trauma especially for splenic
injury. It shows a peri-splenic hematoma with
internal echoes along with one or multiple
lacerations.

14. • Isotope scanning: Rarely used now. Used
whenit is difficult to identify spleen on
USG/CT.
• CT scan: Contrast enhanced CT scan is
investigation of choice. It is have high
sensitivity, specificity and accuracy (>95%) in
detecting splenic injury.

15. CT grading of splenic rupture.

16. • In it splenic lacerations appears as linear low
attenuation defects that contrast well with
high attenuation vascular spleen.
• Intra splenic hematomas appear as more
diffuse hypo-attenuating region with irregular
margins with splenic swelling.

17. Grade IV Splenic rupture

18. Grade III splenic rupture

19. • Uniform enhancement occurs approximately 50-60
seconds after contrast administration, so imaging
during early arterial phase is useful in detection of
active extravasation and for pseudo-aneurysms.
• Thing to remember when suspecting splenic injury is
that during early phase of enhancement the cord like
geographical enhancement of pulp may look like intra-
splenic lacerations. So to rule these out a delayed
supplementary confirmatory images should be taken.
• Scanning upto pelvis should be done because
sometimes hematoma can only be seen as
hemoperitonium in pelvis.

20. • Angiography: It may be used in
hemodynamically stable patients with splenic
injury diagnosed on CT to detect whether
active extravasation is present or not. So that
cases who are hemodymanically stable with
active extravasation can be treated with bed
rest or embolization of splenic artery distal to
dorsal pancreatic artery.

22. Splenomegaly

23. • X-ray: May show a lump in splenic region with
raised diaphragm.
• USG: Enlarged spleen is seen extending
downwards, anteriorly and to the right,
displacing stomach forwards and medially
with left diaphragm seen pushed upwards.
• CT scan: Shows full extent of spleen.

24. Massive splenomegaly in Gaucher’s
disease

25. Splenic masses
1. Splenic abscess: They are rarely seen in
spleen. May be solitary or multiple.
• X-ray: Gas transradiancy is seen i.e. a fluid
level is seen within the splenic mass in erect
radiograph. It is rarely seen but is enough to
make a doagnosis.

26. • USG: Appearance shows a transition with
time. Early stage shows an ill defined mass
with decreased reflectivity, which may
develop fluid components, debris and
septations. In late stage capsule may develop
and gas within abscess will be seen as focal
areas of high reflectivity with acoustic
shadowing.

28. • TB also causes splenic abscesses, in miliary TB
lesions may or may not be identifiable on USG
depending on their size.
• Fungal abscess is seen in immunocompromised
patients. Usually appears as central area of
increased refelctivity which is surrounded by area
of decreased reflectivity . If necrosis occurs
centrally, the center shows decreased reflectivity
and shows ‘Wheel within wheel’ appearance.

29. Miliary TB

30. • CT scan: They appear similar to infarcts and
hematomas i.e. centrally low density lesions
(20-40 HU ) within splenic parenchyma. .
Minimal peripheral contrast enhancement
may be present when a capsule has developed

31. Splenic abscess CT

32. 2. Primary splenic malignancy: Very rare in
occurance but angiosarcoma can occur as multiple
focal lesions.
• USG features are non specific and include
splenomegaly with cystic and solid masses with
mixed echogenicity.
• CT may show solitary or multiple nodular masses
of heterogeneous low attenuation in an enlarged
spleen. There are generally irregular and poorly
defined contours. Some of these masses may
show peripheral enhancement.

33. 3. Metastases: Of all metastases 7% is seen in spleen.
Occurs genereally in presence of wide spread metastases
elsewhere. Lymphomatous involvement of spleen is
relatively common where there is splenic enlargement
without an identifiable focal abnormality.
These lesions are usually necrotic and are seen as low
density lesions on CT. They show ring enhancement on
contrast study.
On USG they most commonly appear as a hypoechoic
lesion, although can be iso- or hyperechoic.

34. Metastases on CT

35. 4. Splenic cyst: Two types- (i) True cyst: Those containing cellular
lining. Eg Hydatid cyst with multiloculated internal structures,
epidermoid cyst.
(ii) False cyst: Those without cellular lining. They are formed due
to previous splenic infarction, infection or trauma.
• USG: Well defined anechoic structure with well defined
rounded margin and posterior acoustic enhancement is seen.
• CT: Typically shows a hypo attenuating relatively well defined
intrasplenic lesion. The wall is thin and has a demarcation to
splenic parenchyma. There is no rim or internal enhancement.
Wall calcification may be present.

36. Hydatid cyst of Spleen

37. Splenic infarcts
• Most common cause of infarcts is embolism from
cardio-vascular disease followed by thrombosis from
hematological diseases, eg sickle cell disease, DIC, etc
• USG: They appear as hyporeflective to areflective in
acute phase and appear wedge shaped in peripheral
location. Chronic infarcts appear as area of increased
reflectivity with atrophy of spleen due to scarring.
Multiple and repeated infarcts leads to shrunken spleen
known as Auto-splenectomy, seen in Sickle cell disease.

38. Splenic infarcts on USG shows no
blood supply in infarcted region.

39. • CT scan and Radionuclide scan: Typically seen
as localized wedge shaped defects in splenic
parenchyma.
In the chronic phase, infarcts may disappear
completely, but more commonly, they may
reveal progressive volume loss caused by fibrotic
contraction of the infarct.

40. Massive Splenic infarct on CT

41. Splenic Calcification
• Calcification in or adjacent to the spleen is common,
especially after age of 50. Calcific plaque in splenic
artery are frequent chance findings on abdominal X-
rays.
• Splenic vein calcification is uncommon but may follow
portal pyaemia or splencetomy.
• Splenic TB granulomas may produce single or multiple
well defined calcification in the parenchyma on X-ray.
• Splenic cyst may show curvilinear or oval calcification.
• A complete infarcted spleen appears as small curved
calcified structure.

42. SPLENIC CALCIFICATION (TB)

43. MRI in SPLEEN
• Anatomy and internal structures are well shown on CT
and USG, but MRI is useful in minority of cases.
(i) Portal hypertension: spleen is enlarged with no
change in it’s signal intensity apart from the
occasional findings of siderotic nodules (Gamna-
Gandy bodies) which produce focal areas of low
intensity signals.
(ii) In Transfusion haemosiderosis, the spleen shows
generalized loss of signal in both T1 and T2.
(iii) Cysts: unifirm low T1 signal, high T2 signals and no
enhancement with gadolinium.

44. • (iv) Haemangioma: Clear well defined margins
with lobulated shape. Uniform low T1 signal and
uniform T2 signal. Dynamic imaging after
gadolinium shows dense peripheral
discontinuous nodular blush, which begins during
arterial phase of liver perfusion and continues
centripetally for several minutes, so that images
taken after 10 minutes often show diffuse
hyperintensity of the lesion. Large haemangioma
may show unenhanced central core even on
delayed imaging.

45. • (v) Abscess: Rim enhancement on gadolinium
is seen in abscess larger than 1.5cm in size.
But it is also a feature of metastases with
necrotic centers.

46. Splenic Scintigraphy
• Very rarely used or needed now a days.
• Physiology: Reticluoendothelial cells of spleen takes up
intravenously injected colloids (99mTc) of size 30-
1000nm. In normal cases about 15% of the injected
colloidal acitivity reaches spleen, but in patients with
cirrhosis or hypersplenism a much greater propoprtion
of injected particles will reach spleen and will be
trapped there due to increased blood to the spleen.
• A more specific imaging is done by injecting autologus
RBC’s which have been incubated at 50° C and labelled
with technetium 99. They are called Heat damaged
RBCs.

47. • It is first choice of technique when localization
of site of functioning splenic tissue in the
absence of a normal spleen on CT or USG, i.e.
in cases of polysplenia/asplenia syndrome.
• Autologous platelets labelled with indium-111
is used to demonstrate rate of clearance of
circulating platelets in patients with Idiopathic
thrombocytopenic purpura, who may be
benefited with splenectomy.

48. Portal Venography
• Methods: (i) Late phase superior mesentric
angiography.
(ii) Trans-splenic approach. (Discussed below)
(iii) Paraumbilical vein catheterization.
(iv) Transjugular transhepatic approach.
• Indications: (i) To demonstrate prior to operation
the anatomy of the portal system in patients with
portal hypertension.
(ii) To check the patency of a portosystemic
anastomosis.

49. • Technique for Trans-splenic approach:
 With patient in supine, spleen is identified on USG. Access point must be as low as
possible in the mid axillary line, usually at the level of 10th or 11th intercostal space.
 The region is anaesthetized.
 Patient is asked to hold the breath in mid-inspiration and the needle is then
inserted inwards and upwards into the spleen. Blood will flow back if needle is in
right place. The patient is then asked to breath as shallowly as possible to avoid
trauma to the spleen.
 The small test dose of contrast media (LOCM) can be injected to ensure correct
siting of the cannula.
 When cannula is in right position the splenic pulp pressure can be measured with
manometer (10-15 cm H₂O)
 A hand injection of 50ml of contrast medium is made over 5seconds and recorded
by rapid serial radiography/digital subtraction angiography. Cannula should be
removed as soon as possible after injection to minimize trauma to spleen.
 Occasionaly portal vein will fail to opacify , owing to major portosystemic
collaterals causing reversed floe in portal vein. The final arbiter of portal vein
patency is direct mesentric venography performed at operation. The maximum
width of normal portal vein is said to be 2cm.

50. THANK YOU