Download Imaging Anatomy of the Liver

IMAGING
ANATOMY OF
THE LIVER
FLIP OTTO
DEPT. OF RADIOLOGY
UNIVERSITAS ACADEMIC HOSPITAL
30 MARCH 2012
OVERVIEW
• Superficial anatomy
• Segmental liver anatomy
• Arterial blood supply
• Portal venous system
• Venous drainage
• Lymphatic drainage
• Radiological features
SUPERFICIAL ANATOMY
AND RELATIONS
SEGMENTAL LIVER
ANATOMY
SEGMENTAL LIVER
ANATOMY
Couinaud classification:
• Liver devided into 8 functionally independent segments, each with
own vascular inflow, outflow and biliary drainage
• Triad of portal vein, hepatic artery and bile duct in centre
• Hepatic veins at periphery – intersegmental
• Middle hepatic vein devides into left and right lobes – Cantlie’s line
• Right hepatic vein devides right lobe into anterior and posterior
segments
• Left hepatic vein devides left lobe into medial and lateral parts
• Portal vein devides liver into upper and lower segments
ARTERIAL BLOOD
SUPPLY
VARIATIONS IN HEPATIC
ARTERIAL ANATOMY
• Replaced common hepatic artery in 2.5%
• Replaced right hepatic artery in 10%
• Accessory right hepatic artery in 6%
• Left hepatic artery replaced by left gastric artery in 12%
• Accessory left hepatic arteries from left gastric artery in
13%
• Common hepatic artery may devide early or trifurcate with
gastroduodenal artery
• Hepatic artery may arise seperately from aorta and not
from the coeliac trunk
VARIATIONS IN
HEPATIC ARTERIES
PORTAL VENOUS
SYSTEM
• Portal vein forms posterior to neck of pancreas by union of
SMV and splenic vein
• Anterior to IVC and posterior to bile duct and hepatic artery in
free free edge of lesser omentum
• Devides into right and left portal veins at porta
• RPV devides into RAPV(segments V and VIII) and
RPPV(segments VI and VII)
• Variations include trifurcation of PV into RAPV, RPPV and LPV;
and RPPV as 1st branch of PV
VENOUS DRAINAGE
• Hepatic veins drain upwards and backwards to IVC
without an extrahepatic course
• Right, middle and left veins drain corresponding thirds of
the liver
• MHV may unite with LHV and have common final course to
IVC
• Smaller veins drain directly to IVC from lower parts of
right and caudate lobes
RELATIONSHIP BETWEEN
PORTAL AND SYSTEMIC
VENOUS SYSTEMS
LYMPHATIC
DRAINAGE
• Deep lymphatics drain in connective tissue along portal
triads and along hepatic veins
• Lymphatics drain to nodes in porta hepatis, hepatic nodes
along hepatic vessels and nodes in lesser omentum
• Via retropyloric nodes to coeliac nodes and cisterns chyli
• Superficial lymphatic network under liver capsule:
• Anterior parts of diaphragmatic and visceral surface drain
to deep lymphatics
• Posterior parts drain to bare area and on to phrenic lymph
nodes; or joins deep lymphatics running along hepatic
veins towards IVC, draining into posterior mediastinal
lymph nodes
RADIOLOGICAL
FEATURES
Imaging modalities
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CT
MRI
Ultrasound
Hepatic angiography
CT angioportography
Portal venography
Hepatic venography
Hepatic scintigraphy
CT OF THE LIVER
CT OF THE LIVER
Single phase (portal phase) contrast-enhanced CT
• Imaged at peak of parenchymal enhancement i.e. portal
venous enhancement 60-70s after start of bolus injection
Multi-phasic contrast-enhanced CT
• Most tumours receive blood supply from hepatic arteries,
therefore enhancing strongly on arterial phase (20-25s after
start of bolus)
• Early and late arterial phases, portovenous and delayed
phases according to clinical indication
MRI OF THE LIVER
MRI OF THE LIVER
• Liver parenchyma equal signal intensity to pancreas and
higher on T1 and lower on T2 than the spleen
• Hepatic vessels seen as signal void on standard imaging
• Major hepatic veins and secondary branches of portal
veins visible
• Hepatic arteries not well seen unless iv contrast given
• On T2 ligamentum venosum and ligamentum teres low
intensity with high intensity fat within their fissures
• Common pulse sequences: T1-W GRE with or without fat
suppression; T2-W FSE; heavily T2-weighted
• Contrast-enhanced MRI: Gd-enhanced T1-W; Liver
specific contrast agents e.g. SPIO for RE cell imaging
ULTRASOUND OF THE
LIVER
ULTRASOUND OF THE
LIVER
• Liver particularly suited for ultrasound imaging
• Also used as acoustic window for viewing other
structures: right kidney and adrenal gland, gallbladder and
pancreas
• Vessels and bile ducts particularly well seen
• Blood flow studied using colour flow Doppler and
direction and velocity of flow inn portal vein evaluated
with pulsed wave Doppler
• US contrast media can help characterise lesions
HEPATIC
ARTERIOGRAPHY
HEPATIC
ARTERIOGRAPHY
• Catheter introduced into aorta and coeliac trunk via
femoral puncture
• Greater selectivity if contrast injected distal to origin of
gastroduadenal artery
• Frequency of normal variation may make injection of SMA
and left gastric arteries also necessary
• MR and CT angiography can also produce excellent
images of coeliac trunk and SMA
CT
ANGIOPORTOGRAPHY
• Was more commonly performed pre-operatively before
universal availability and improved capabilities of MRI to
identify liver tumours or metastases in patients
considered for resection
• CT performed 60s after selective injection of contrast into
SMA; in portovenous phase
• Portal perfusion defects on CTAP in segments I, IV and
around falciform ligament in 10% of patients due to nonportal venous inflow directly into subsegmental hepatic
parenchyma
PORTAL
VENOGRAPHY
PORTAL
VENOGRAPHY
Direct portography
• Splenoportography
• Transjugular transhepatic approach
• Transumbilical portography by catheterizing the umbilical vein
Indirect portography
• Late phase superior mesenteric angiography
HEPATIC
VENOGRAPHY
HEPATIC
VENOGRAPHY
• Acieved via the IVC usually by retrograde approach
through internal jugular vein
• Catheterization of three main hepatic veins in turn
• May also achieve radiographically-directed hepatic
venous pressure measurements or transjugular biopsy or
TIPS
HEPATIC
SCINTIGRAPHY
Tc-99m colloid scintigraphy
• Taken up by phagocytosis by RE cells
• Rarely used to diagnose metastases or tumours, but helpful to
identify benign focal nodular hyperplasia and to evaluate liver
function e.g. liver cirrhosis
Tc-99m IDA scintigraphy
• Excreted by hepatocytes into bile, allowing assessment of biliary
drainage and gallbladder function
Tc-99m labelled RBC imaging
• Highly specific for diagnosing cavernous haemangioma
F-18 FDG PET and In-111 Octreotide in oncological imaging
REFERENCES
• Aitchison, F. (2009) A Guide to Radiological Procedures.
5th ed. London: Saunders Elsevier.
• Butler, P., Mitchell, A.W.M. & Ellis, H. (1999) Applied
Radiological Anatomy. Cambridge: Cambridge University
Press.
• Ryan, S., McNicholas, M. & Eustace, S. (2011) Anatomy for
Diagnostic Imaging. 3rd ed. London: Saunders Elsevier.