Appropriate use of USG,CT and MRI in liver imaging.

Dr.K.Vinayachandran Nair MD,DM. Encouraging us and asking right questions.

Dr.Jagdeesh MRCPCH ,FRCR. Passion about liver nodules. Also lending many slides.

Few slides taken from google images.

I have to tell stories of 3 heroes… !

• Appropriate use of USG,CT and MRI in liver imaging.

Ultrasound of liver what we can diagnose and what we can not.

Primary liver lesions in cirrhotic liver.CT versus MRI in liver lesions.

65 year old male with dyspepsia , bloating , not alcoholic.

Coarse texture , multiple tiny nodules.

Nodularity of liver contour.

Cirrhosis of liver.

Surface nodularity with high frequency probe.

Caudate to right lobe ratio more than 0.65 specific for cirrhosis.

Portal vein diameter is not sensitive in detecting portal hypertension.

Color doppler is to confirm direction of flow , reversal indicates portal hypertension.

Splenomegaly and collaterals are indicative of portal hypertension.

Increase of less than 20% in diameter of portal vein with deep inspiration indicates portal hypertension.

Very difficult criteria …!

Sensitivity and specificity varies from 60-100% according to different studies.

World journal gastroenterology..2010.

Other criteria include Cork screw / enlarged hepatic artery. Loss of phasicity and pronounced cardiac

periodicity. Reduced portal vein velocity. Congestion index (ratio of area to flow

velocity)

Is controversial. May not be beneficial USG is not useful in detecting small (1-

2 cm) HCCs (sensitivity of 13 %). More sensitive in detecting larger

( more than 4 cm) HCCs(sensitivity of 75%)

Can not differentiate between dysplastic nodule and HCC.

AJR July 2002

Small HCC Large HCC

Diffuse type HCC , no mass detected on USG. Liver transplantation surgery showed diffuse HCC.

Slide taken from AJR

IT CAN DIFFERENTIATE TUMOR FROM BLAND THROMBUS.

Portal vein

Agents such as perflubutane microbubble cause contrast related enhancement of focal liver lesions.

Enhancement pattern is used to assess cellular differentiation of HCCs.

This can be repeated realtime. AJR

Enhancement and washout in a poorly differentiated HCC

AJR

A technique to assess fibrosis of liver.

Employs modified ultrasound probe which assesses velocity of a shear wave created by a vibratory source.

Values of above 12.5kPa are indicative of cirrhosis.

50 year old male with Progressive abdominal distension.

? Mass in right upper quadrant

Lack of visualization of hepatic veins and narrowing of caliber of IVC indicating Budd Chairi syndrome. A difficult diagnosis on USG needs IVCgram for confirmation.

20 year old nursing student studying in Karnataka has come to emergency with right upper quadrant pain , not jaundiced --? cholecystitis

LFT showed elevated transaminases.Hepatitis A IgM marker positive.Final diagnosis – anicteric viral

hepatitis.

Radiology assistant www.radiologyassistant.nl

Reason for showing this case is that there are no specific sonographic findings for hepatitis.

Reduced echotexture of liver , gall bladder wall thickening , hepatomegaly , starry sky appearance of liver due to periportal edema are described findings.

27 years old male working as executive in a company comes with elevated liver transaminases.

Claims to be teetotaller.

Increased liver texture indicating fatty liver.

Liver echogenicity exceeds that of right kidney and spleen.

And There is beam attenuation.

Most often subjective..!!Grade 1– increased texture with

good visualization of diaphragm and intrahepatic vessels.

Grade 2- mild impairment of visualization.

Grade 3– severe impairment of visualization.

Here there is fatty infiltration , hepatomegaly and elevated liver enzymes. (AST and ALT).

Histologically, there is inflammation and fibrosis.

Radiologically it is not possible to separate NASH from ordinary fatty liver.

Fatty liver involves about 15% of population.

NASH involves about 2-5% of population.

Focal fatty infiltration can simulate mass.

Focal fatty sparing can also mimic mass.

25 year old healthy male for employment health checkup.

When USG shows hemangioma typical features in a nononcology patient this modality alone is considered sufficient.

Not sensitive in detecting small HCCs.

Can not differentiate between HCC and dysplastic nodule.

Entire liver can not be assessed , few USG blind areas in liver.

Moderate sensitivity in detecting cirrhosis.

Hemangioma in a nononcology patient , cyst and to certain extent abscesses can be confidently diagnosed with USG, for other focal lesions one needs to assess further.

Varying signals; varying sizes, varying enhancement

Siphon out the dysplastic nodules & HCC!!

How!

Lesions MRI features:-post contrast behaviour

Intermediate/vague features/cross over features

Varying signals; varying sizes, varying enhancement

Siphon out the dysplastic nodules & HCC!!

How!

Lesions MRI features:-post contrast behaviour

Intermediate/vague features/cross over features

Varying signals; varying sizes, varying enhancementSiphon out the dysplastic nodules & HCC!!

How!

Lesions MRI features:-post contrast behaviour

Intermediate/vague features/cross over features

T2,

T2FS

T1

T1 in and opposed phase

Dynamic post contrast T1FS(fat saturation) with subtracted images

Regenerative Nodules ; Siderotic nodules

Dysplastic Nodules

HCC  

Size - diameter of less than 2 cm are more likely to be

benign than malignant

Vascularity - shift from predominantly venous perfusion to

predominantly arterial perfusion - dedifferentiated nodules - markedly enhanced on early arterial phase

Hepatocellular Function - hepatocellular contrast agents

most common cirrhosis-associated hepatocellular

nodules  T2 : Isointense to liver; hypointense ( iron) T1: Variable Postcontrast: - No arterial enhancement - isointense enhancement to the liver - washout isointense to liver

Low grade and high grade T2 : hypointense or isointense to liver, T1: Variable Postcontrast: - Patchy ill defined nodular arterial enhancement - isointense enhancement to the liver - hypointense to liver in the later

phases, no definite tumor capsule

T2 : Hyperintense ( 94%) – isointense to spleen T1: Variable Postcontrast: - Intense arterial enhancement - isointense on the portal venous

phase - wash out on the later phase with

persistent tumor capsule

T1- and T2-weighted MR images, the mosaic pattern appears as areas of variable signal intensities

lesions enhance in a heterogeneous fashion during the arterial and later phases

Diffuse type HCC a permeative tumor often with portal vein thrombus.

LESION T2 T1 ART DEL

Reg N Low-iso Int - High No enhancement No wash out

Dys N Low-iso Int - High Heterogenenous moderate enhancement

Irregular wash out with no capsule

HCC Int - High Low - Int Intense enhancement

Wash out with enhancing capsule

CT versus MRImosaic pattern- 88%

T1- and T2-weighted MR images, the mosaic pattern appears as areas of variable signal intensitieslesions enhance in a heterogeneous fashion during the arterial and later phases

When doing survey for metastasis , CT is better as it can assess extra hepatic lesions better than MRI.

In patient with chronic liver disease , for characterization of regenerative ,dysplastic nodules and HCC , MRI is better than CT.

There are several arterial phase enhancing lesions.

TAHD – transient hepatic attenuation difference.

Confluent hepatic fibrosis.

Contrast MR has sensitivity of near 81% and specificity of near 85%.

CT has sensitivity of near 73% and sensitivity of near 93%.

Imaging not sensitive for lesions less than 20 mm and diffuse lesions.

USG is the first line modality in liver imaging. Used to rule out liver disease and diagnose with confidence common lesions like cysts and hemangiomas.

Multiphasic CT is the standard reference study in liver disease. Standard in assessing and follow up of oncology patients. When high resolution MRI is not available can be used to image cirrhosis.

MRI is modality of choice in assessing cirrhosis liver . It is increasingly preferred in follow up of patients and in children where radiation is an issue.

Tissue specific contrast agents are being available and are helpful.

Biopsy or follow up is advised in doubtful lesions or histopathological confirmation is necessary for management.

Decisions should be patient specific.

Diffusion weighted imaging

Mixed extracellular and hepatocellular contrast agents

-gadoxetic acid disodium 

MR spectroscopy

Liver perfusion

Diffusion imaging liver.