Triphasic CT (TPCT) Scan of the liver is essential in view of the dual blood supply of the liver. TPCT allows characterisaiton of all liver lesions and close to pathological correlaiton by non invasive imaging alone. Additionally providing segmental vascular analysis as a surgicical guide.
3. TPCT Liver
Technique
Pre-contrast – Deferred in follow up / Metastasis,
Arterial phase of contrast enhancement
Portal phase of contrast enhancement
Veinous Phase – Equilibrium
abdominal CT is completed to iliac crest level.
Hemangioma is suspected – additional delayed images
to assess for filling in of hemangioma.
4. Technique
Iodinated Contrast
Nonionic
Serum Creatinine
eGFR – Estimated Glomurelar Filtration rate
Contrast Dose – 2 ml / kg maximum of 150ml
Rate of Injection – 4 ml / sec at 300 psi
IV cannula – 18 to 20 guage
Multi Slice CT – Reduce the contrast Dose
Arterial Phase – Timing and Rate
Veinous Phase – Total Iodine Dose
5. Technique
Timing of scan
Arterial – bolus tracking 18 to 25 sec
Portal – 45 sec
Veinous – 65 sec
Collimation – Spatial resolution / Image noise
Pitch – 1.25 : 1
Table speed of 15 mm / Rotation
Reconstruction interval – 1.5 overlap 0.75
Kvp / mAs – 120 / 225
FOV 350
High Quality, Large volume, Reasonable radiation dose
to Obtain 3D Multiplanar images in single breath hold.
7. Dual Blood Supply
Normal parenchyma is supplied for 80% by the portal vein and
only for 20% by the hepatic artery,
normal parenchyma will enhance maximally in the hepatic veinous phase
at 65-75 sec p.i. and only a little bit in the late arterial phase at 18 - 35 sec p.i..
8. Lesion Characterization
All liver tumors however get 100% of their
blood supply from the hepatic artery.
Hypervascular tumor will be best seen
in the late arterial phase.
Hypovascular liver tumor enhances poorly in the
late arterial phase, difficult to differentiate from
the poorly enhancing liver parenchyma
Best seen when the surrounding tissue enhances,
i.e. in the veinous phase at 65-75 sec p.i.
18. Veinous phase at 65 sec p.i.
Fibrotic lesions like
Cholangiocarcinoma
Fibrotic metastases
hold the contrast much longer than normal parenchyma.
Lesion Characterization
19. Cholangiocarcinoma
High recurrence rate (77%) metastases recurrence (60%)
Absolute contraindication to transplant
Predisposition seen with primary sclerosing cholangitis
Early peripheral enhancement with peripheral delayed filling
Mass forming intrahepatic lesion with ductal invasion
20. Lesion Characterization
Pre contrast Arterial Phase Venous phase Delayed
HCC Low attenuation
Homogenous
enhancement
Washout Isodense
Adenoma Low attenuation
Homogenous
enhancement 85%
Iso or hypodense
Iso or
hypodense
FNH
Iso/Low
attenuation
Homogenous
enhancement
Hypodense Isodense
Haemangioma Low attenuation Peripheral puddles Centripetal filling Complete fill in
Cholangiocarcinoma Low attenuation Iso attenuation Enhancement Isodense
Hypervascular
Metastases
Low attenuation
Homogenous
enhancement
Hypodense
Hypovascular
Metastases
Low attenuation Hypodense Hypodense
Cyst Low attenuation No enhancement
Abscess Low attenuation
may have
irregular margins
Transient regional
enhancement
Wall
enhancement
22. Liver Transplant Imaging
MELD Score (Model for End-Stage Liver Disease)
TIPS – Transjugular Intrahepatic Portosystemic Shunting
3 month mortality
Prognostication Prioritize Liver transplant
Serum bilirubin, Serum creatinine and PTINR
Dialysed 2 x 7 days – Sr. Cr. 4.0
Value of 1 of any unit below one
MELD = 3.78×ln[S Bil. (mg/dL)] + 11.2×ln[INR] + 9.57×ln[S Cr. (mg/dL)] + 6.43
3 month mortality in hospitalized patients
≥ 40 – > 70% mortality
30 – 39 – 52.6 %
20 – 29 – 19.6%
10 – 19 6.0%
< 9 – 1.9% mortality
Mayo Clinic by Dr. Patrick Kamath
Mayo End-stage Liver Disease Score
23. Milan criteria
Defined as 1 tumor ≤5 cm;
or ≤3 tumors with each tumor ≤3 cm
UC.SF criteria
Defined as 1 tumor ≤6.5 cm
or ≤3 tumors with the largest tumor diameter
≤4.5 & total tumor diameter ≤8 cm
TNM Classification
Defined as Stage 1 – 1 Tumor ≤ 1.9cm
Stage 2 – 1 Tumor 2-5cm or upto 3 each ≤3cm
Without extrahepatic metasteses
Liver Transplant Imaging
26. Arterial Anatomy
30 % donors may be rejected – unsuitable arterial anatomy
Right and left HA arising from CHA Type 1
Segment IV artery may be a branch of RHA or LHA
3D Volume rendered images – Digital subtraction angiography
27. Portal Vein
Main portal vein – bifurcates in Rt and Lt branch – Type A
Right branch is considered continuation of MPV
Trifurcation of protal vein – Type B require Dual anastomoses
28. Hepatic Vein
Right, Middle and Left Hepatic veins drain to IVC
Accessory vein usually in segment VIII of right lobe (6%)
Volume rendered 3D images
29. Volumetry
Manual tracing – very accurate
Automatic and Semiautomatic Segmentation
Interactive Semiautomatic
Substantially less user time 1 min / case
Manual upto 45 minutes / case
Semiautomatic 15 minute / case
IntelliSpace Portal Liver Analysis Application
Phillips
30. 9 anatomical landmarks
Liver segmental localisation
Volumes with and without vessels
Transplant segment volume calculation
Remnant volume
Volumetry
31. A – First bifurcation of Right Portal vein
B – Inferior Vena Cava
C – Right Hepatic vein
D – Middle Hepatic vein
E – Left Hepatic vein
Volumetry
32. F – Superficial ligamentum venosum
G – Deep ligamentum venosum
H – end of Left Portal vein
I – Left Liver tip
Volumetry
33. x
x
x
Automated outline of the entire liver with corrections for
false positive and false negative extractions
Manual positioning of 1st
landmark at bifurcation of RPV
Volumetry
34. x
x
x
Volume rendered image with automated volume calculation
“Segments of Couinaud”
Transverse image after manual correction of the false
positives and false negatives
Volumetry
38. Volumetry
Potential Donor / Surface area
Minimum 40% normal liver
volume is needed by recipient
Minimum 35% remnant liver
volume is left with donor
If you want to characterize a liver lesion, you need maximum contrast at a maximum flow rate, i.e. 150cc contrast at 5cc/sec. through a 18 gauge green venflon.
In most cases you also want to scan the whole abdomen.You can do this either at 35 sec or 70 sec p.i.
D/D central calfication – Fibrolamellar carcinoma - Age group: 5 - 35yrs
Spontaneous
No predisposing factor
Solitary lobulated well defined tumor containing a central fibrous scar.
Punctate calcification- in scar &gt;50% cases
CT precontrast phase (A), Arterial Phase (B) Portal veinous (C) and equiblirium (D)
Peripheral globular uptake and the centripetal filing
Commonest benign tumor
Asymptomatic
Large vascular channels filled with slowly flowing blood
F&gt; M (5:1)
Multiple in 10% cases
2-4cms-typical characteristic
CT precontrast phase (A), Arterial Phase (B) Portal veinous (C) and equiblirium (D)
Peripheral globular uptake and the centripetal filing
CT precontrast phase (A), Arterial Phase (B) Portal veinous (C) and equiblirium (D)
Peripheral globular uptake and the centripetal filing
Fatty liver – Steatosis – predisposed by Diabetes, Hyperlipidemia and steroid use.
Fatty liver – Steatosis – predisposed by Diabetes, Hyperlipidemia and steroid use.