Diagnostic Ultrasound - Abdomen and Pelvis

Splenomegaly
TERMINOLOGY
Abbreviations
• Splenomegaly (SMG), hypersplenism (HS)
Definitions
• SMG: Increased splenic size, length > 13 cm in adults,
weight > 250 g
• HS: Clinical syndrome consisting of SMG and pancytopenia
IMAGING
General Features
• Best diagnostic clue
○ Increased size of spleen
• Location
○ Spleen occupies left upper quadrant (LUQ) with tip
extending inferiorly below 12th rib
• Size
○ No universal consensus on SMG cutoff due to variability
in normal spleen size
– Generally, normal adult spleen considered 12 cm in
length (longest diameter in longitudinal plane), 4 cm
in thickness (transverse from hilum), and 7 cm in width
(longest diameter in transverse plane)
○ SMG is diagnosed when length > 13 cm; additional
measurements of thickness > 5 cm or width > 8 cm can
be used
○ Splenic index (product of length, thickness, and width):
Normally 120-480 cm³; SMG considered index > 500 cm³
○ Splenic size correlates with height and can exceed
normal size in tall, healthy people
○ SMG can be subjectively characterized as mild, moderate,
or severe
– Mild: Mononucleosis, febrile/bacterial infections, CHF
– Moderate: Portal HTN, acute leukemias, thalassemia,
TB, amyloidosis, sarcoidosis
– Severe: Chronic leukemias, chronic myeloproliferative
disorders, lymphoma, malaria, Gaucher disease
• Morphology
○ Enlarged spleen tends to have bulging shape and
rounded poles
Ultrasonographic Findings
• Grayscale ultrasound
○ Normal splenic parenchyma is homogeneous;
hyperechoic compared to liver and kidney
○ SMG with altered parenchymal echogenicity can be seen
in different etiologies (some overlap)
○ SMG with normal echogenicity
– Infection (mononucleosis, Salmonella typhi),
congestion (portal HTN), early sickle cell disease
– Hereditary spherocytosis, hemolysis, Felty syndrome
– Wilson disease, polycythemia, myelofibrosis, leukemia
○ SMG with hyperechoic pattern
– Leukemia, lymphoma, sarcoidosis, metastasis
– Infections (malaria, tuberculosis, brucellosis),
hematoma
– Hereditary spherocytosis, polycythemia, myelofibrosis
○ SMG with hypoechoic pattern
– Leukemia, lymphoma, metastasis, multiple myeloma
– Congestion (portal HTN), noncaseating
granulomatous infection
– Sickle cell sequestration crisis: Peripheral hypoechoic
areas
– Gaucher disease: Multiple well-defined, discrete,
hypoechoic lesions; fibrosis or infarction
○ SMG with mixed echogenic pattern
– Abscesses, metastases, infarction,
hemorrhage/hematoma in different stages of
evolution
• Color Doppler
○ Portal hypertension: Dilated splenic vein (SV); direction
of flow may be reversed; SV thrombus, splenic hilar
collaterals, splenorenal shunt, recanalized umbilical vein
Radiographic Findings
• Radiography
○ Unreliable for determination of SMG
○ Splenic tip extending below 12th rib
○ Severe SMG may displace stomach and splenic flexure of
colon
CT Findings
• Congestive SMG
○ Portal hypertension: SMG with varices, nodular shrunken
liver, ascites
○ SV occlusion or thrombosis (i.e., secondary to
pancreatitis or pancreatic tumors)
○ Sickle cell sequestration crisis: Peripheral low- & highattenuation
areas (areas of infarct & hemorrhage)
• Space-occupying lesions: Cysts, abscess, tumor
○ Cysts: Hypodense on NECT, no enhancement on CECT
○ Abscess: Hypodense on NECT with irregular, shaggy
margin enhancing on CECT
○ Tumor: Hyperdense/hypodense on NECT and variable
enhancement on CECT
• Storage disorders
○ Amyloidosis
– NECT & CECT: Generalized or focal ↓ attenuation
○ Hemochromatosis
– Primary: Spleen size normal or enlarged; normal
attenuation compared to liver
– Secondary (hemosiderosis): SMG with ↑↑ attenuation
• Splenic trauma
○ Splenic laceration or subcapsular hematoma,
surrounding perisplenic hematoma (> 30 HU)
MR Findings
• Congestive SMG
○ Portal hypertension:Multiple tiny (3-8 mm) foci of
decreased signal, hemosiderin deposits (siderotic
nodules, a.k.a. Gamna-Gandy bodies)
○ Sickle cell sequestration crisis:Areas of abnormal signal
intensity, hyperintense with dark rim on T1WI (subacute
hemorrhage)
• Infarction:Peripheral, wedge-shaped areas of hypointensity
resulting from iron deposition
• Secondary hemochromatosis (hemosiderosis): ↓ signal
intensity on T1- and T2W1, GRE
Nuclear Medicine Findings
• Chromium 51-labeled RBCs or platelets
Diagnoses: Spleen
401