SAVED
File name .JPG
File alt. text
Image should be px wide x px tall.
Select Image
home - Liver - Liver Imaging - Liver Imaging USS Written by Dr Sebastian Zeki

Liver Imaging USS

Color flow Doppler ultrasoundUses: Tumour-induced occlusion of major hepatic vesselsDuplex Doppler ultrasonographyCalculates frequency, amplitude, and flow direction.These features is important in the following circumstances:-Flow rate important post TIPS insertion.-Flow characteristics, eg inc flow resistance in rejecting livers (systolic wave peaking and no antegrade diastolic flow), or Tardus-Parvus waveform pattern assoc.with hepatic artery stenosis to evaluate the newly transplanted liver.-The duplex to-and-fro waveform has a characteristic diagnostic pattern in suspected arteriovenous fistulae following liver biopsies.Contrast agents3 contrast phases:-Arterial phase (hepatic artery) starts 10-20s post ivi; lasts for 10-15s.-Venous phase (portal vein) extends from 30-35s to 120s.-Late phase starts at 120s; lasts up to 5m post-ivi with the disappearance of bubbles.CO2 microbubbles injected into the hepatic art of patients with small (<3 cm) HCCs enhance most tumors, with a greater sensitivity for hypervascular lesions than conven-tional USS, angiography, or CT.Normally phagocytosed by the reticuloendothelial system and remain in the spleen and liver for a least two days, resulting in a rim-like region of increased echogenicity around tumors.Patterns seen with common hepatic lesions include the following:-Hemangiomas: peripheral globular contrast pooling in the early phase (cotton wool appearance);globules get larger and more numerous (centripetal fill-in).-Focal nodular hyperplasia: centrifugal stellate branching in early arterial phase then intense homogenous uptake (spoke wheel pattern). Rapid washout occurs thereafter with iso-/hyperechoic lesion is seen in portal venous phase.-HCC: Strong enhancement in arterial phase with +1 feeding arteries at periph; Intense global pooling in late arterial phase is followed by a rapid washout in the portal venous phase.Contrast US detects more liver mets than conventional US esp <1 cm lesions/ subcapsular or ventral locations/around ligamentum teres.Utility of contrast US reduced in severe steatosis/deep lesions 6. Screening for HCC7. Evaluation before and after liver transplantationPortal vein patencyDetects portosystemic shunts- can affect transplant outcome +predicts hepatic artery thrombosis based upon Doppler wave form.8. Follow-up of TIPSDoppler USS v. se and sp for blood flow velocity in stent+predicting stent stenosisSonographic criteria for stent stenosis include :-Low velocity flow (< 60 cm/sec) within any portion of the stent-Low flow velocity with focal velocity increase, usually at hepatic v. end of stent-Flow gradient inc >100 % from portal to hepatic v. ends-A temporal change in peak flow velocity of >50 cm/sec from the post TIPS baseline sonogramIdentification of new hepatopedal flow in the left portal vein or a newly recanalized periumbilical vein are indirect evidence for stent malfunction since left portal venous flow usually reverses towards the stent The gallbladder wall should be < or equal to 2 mm (in a distended or fasting gallbladder). Collapsed gallbladders, seen when the subject has eaten, typically appear The maximum dimension of the gallbladder is 5 X 10 cm. Common hepatic duct (inner wall to inner wall) is usually measured at the level of hepatic artery.In the normal fasting state it should be <7 mm in patients <60 years, and <10 mm in patients older than 60. CBD up to10 mm post cholecystectomy. 1. Differentiate cystic from solid lesions 2. Delineating septa-tions within cystic lesions such as biliary cystadenomas. 3. Can identify certain solid lesions eg fatty infiltration or haemangiomas 4. Evaluation of right upper quadrant painSe for gallstones >95 % (better than CT)Se for cholecystitis (gallbladder wall thickening and localized tenderness over the gallblad-der (Murphy's sign)).Se for CBD stone= CT (75 % if dilated ducts, 50 % for nondi-lated) so if inconclusive, MRCP preferred5. Evaluation of obstructive jaundiceSe for dilated bile ducts and biliary obstruction up to 91 %. (length of bilirubin and concen-tration increase sensitivity) Liver Imaging- USS Clinical Use 9. Liver tumor staging and treatmentAssess portal vein patency and whether is tumour ingrowth (has an arterial signal) or a thrombusAssess size, number, and exact location and extracapsular spread of liver tumors.The sensitivity for mets to liver is 85 %.10. Diagnosis of ascitesCan be used to guide paracentesis11. Intraoperative and laparoscopic ultrasoundGood for small (2 to 5 mm) mets in segmental liver resections.It is particularly well suited for imaging the biliary system. Written by Dr Sebastian Zeki USS Types

Related Stories

•The Quality Assessment of Virtual Unenhanced and Blending Images Derived from Dual-Energy CT for Detecting Colorectal Cancer

•Toward Optimized Intravoxel Incoherent Motion (IVIM) and Compartmental T2 Mapping in Abdominal Organs

•Bridging the gaps in fibroblast activation protein targeted radionuclide therapy: a translational perspective

•Dose heterogeneity in transarterial radioembolization after fractional administration of holmium microspheres: a study in perfused human tumor-bearing liver explants under MRI

•Reply: From liver to vasculature: An integrated view of cardiovascular risk in hepatic steatosis