Chap 17/19: Contrast Agents and Emergent US procedures

Most research and development has centered on creating agents that can be administered ___________?

Intravenously

What are Limitations of Contrast-Enhanced sonography

• Spatial and contrast resolution on grayscale

• detection of low-velocity blood flow and flow in very small vessels using Doppler flow detection modes

Vascular ultrasound contrast agents (UCAs) enhance Doppler (color and spectral) flow signals by?

adding more and better acoustic scatterers to the blood stream

Clinically useful UCAs must…?

Be nontoxic

Have microbubbles or microparticles small enough to traverse pulmonary capillary beds (ie. less than 8 microns)

Be stable enough provide multiple recirculations

What are Tissue-specific UCAs

Microbubbles of agents removed from the blood pool and taken up by (or have affinity toward) specific tissues such as reticuloendothelial systems (RES) in the liver and spleen or thrombus

How are tissue-specific UCAs typically administered

By intravenous (IV) injection

Which type of Tissue-specific UCA is used in Japan that behaves like a vascular agent

Sonazoid

How to US contrast agents improve accuracy of hepatic sonography:

Enhanced detection and characterization of hepatic masses

Improved detection of intra- and extrahepatic blood flow

What is the order in which enhanced flow is seen in normal situation of IV administration of UCA in Hepatics

Enhanced flow in hepatic artery identified first (arterial or early vascular phase

Followed by enhanced portal venous flow (portal venous phase)

Detection of flow in hepatic capillaries identified later (late vascular phase) as parenchymal blush

What are first to demonstrate contract enhancement in UCA in liver

Hepatic arteries during arterial phase

What are second to demonstrate contract enhancement in UCA in liver

Poral venous flow during portal venous phase

What is the last to be enhanced in UCA in liver

late vascular phase the liver parenchyma becomes echogenic with detection of flow in the hepatic capillaries as a parenchymal blush

During arterial phase, what is enhanced in hemangiomas

only peripheral enhancement

What is enhanced during portal and late phase on a hemangioma

progressive centripetal filling lasting 5-7 min

Hemangiomas get progressively more __________ over time in a CES

echogenic

What pattern is characteristic for hemangiomas

Contrast imaging with blood at the periphery of the lesion and increased echogenicity of the normal liver parenchyma

What is the CES appearance of HCC?

Intense enhancement in the early arterial phase

What is the delayed appearance of HCC using CES

Hypoechoic to surrounding tissue

What has similar appearance to HCC in early arterial phase using CES

Focal Nodular Hyperplasia (FNH)

Whole HCC becomes more hypoechoic in delayed CES imaging, how does FNH look

More isoechoic to surrounding liver tissue

What are the complications of Peritoneal lavage?

Bowel perforation, bladder penetration, vascular laceration and wound complications

FAST scans are used to evaluate free fluid or pericardial fluid, in context of traumatic injury, free fluid is usually due to?

Hemorrhage and contributes to the assessment of circulation

In a FAST scan protocol, where is the initial survey first directed

Subcostal area to look for pericardial effusion

What is the most common site of fluid collection

Subhepatic space (Morison’s pouch), regardless of the site of the injury

What is the second most common space for fluid accumulation

Pelvis, pouch of Douglas

What are some pitfalls of abdominal ultrasound

Failure to show contained solid-organ injuries, injuries to diaphragm, pancreas, adrenal glands and bowel

Obesity, presence of subcutaneous air from a pneumothorax that dissects into the abdominal cavity may collect over the liver or spleen

Free fluid in the female pelvis may be physiological if contained to the cul-de-sac

What are the clinical signs for Cholecystitis (acute)

RUQ pain

Fever

Nausea, vomiting

Leukocytosis

What are the sonographic findings for Cholecystitis

Thickened gallbladder wall

Positive Murphy’s

Pericholecystic fluid

Dilated gallbladder

What are the clinical signs for Pancreatitis (acute)

Midepigastric pain radiating to back

Fever

Leukocytosis: Amylase and Lipase

What are the sonographic signs for pancreatitis

Normal to edematous gland

Hypoechoic texture

Irregular borders

Increased vascular flow

What is the most common cause of acute cholecystitis

Cystic duct obstruction generally by a gallstone

Acute epigastric pain may be secondary to what?

pancreatitis

In pancreatitis, the gland may appear?

sonographically normal to enlarged and hypoechoic texture

Clinical signs for Urolithiasis

Spasmodic flank pain

Pain may radiate into pelvis

Leukocytosis

Hematuria

Fever

What are the sonographic signs of Urolithiasis

Echogenic foci with shadowing

Hydronephrosis may be present

Presence/absence of ureteral jets in bladder

Clinical Signs for Thoracic or abdominal pain: Aortic Dissection

Sudden onset of server chest pain with radiation to arms, neck, or back

Respiratory distress

Syncope may be present (they passed out)

Sonographic sign for Aortic Dissection

Aneurysm - enlarged aorta

Decreased or reversed flow in false lumen

Look for moving echogenic flap at site of dissection

Look for false lumen (echogenic membrane)

What is the most common site for aortic dissection to occur

Occurs in the thoracic cavity at the ascending aorta

What is Pseudo-dissection

Demonstrates a turbulent blood flow pattern, indicating a hypoechoic thrombus near the outer margin of the aorta with an echogenic laminated clot. No intimal flap is seen in pseudo-dissection

What is the most common cause of Aortic dissection?

Hypertension 70% to 90%

What are the clinical findings for Appendicitis

Intense RLQ pain

Nausea/Vomiting

Fever

Leukocytosis

Sonographic findings for Appendicitis

Distended, non-compressible appendix

One of the most common emergent surgeries

Color flow

McBurney’s sign

Clinical findings for Paraumbilical Hernia

Asymptomatic to mild discomfort

Palpable mass

Valsalva: shows exaggeration of mass

Reduce sac with gentle pressure

Sonographic signs of Paraumbilical Hernia

Lower abdominal mass: look for peristalsis of bowel hernia

Most common sonographic findings is peristalsis during and after valsalva

What is the weakest area of the abdomen for hernias

umbilicus

What site is most common for hernia in females

paraumbilical

What site is most common for hernias in males

Inguinal

What are the three classification of hernias

Reducible - visceral contents can be returned

Incarcerated - visceral contents cannot be reduced

Strangulated - incarcerated hernia with vascular compromise

What are the sonographic criteria for a paraumbilical hernia?

Demonstration of anterior wall defect

Presence of bowel loops within sac

Exaggeration of sac during Valsalva

Reducibility of sac with gentle pressure

Torsion occurs as a result of abnormal ________ of the testis within the scrotum and requires emergent surgery

mobility

What is the sonographic appearance of scrotal torsion in the early stage

Normal texture

What is the sonographic appearance of scrotal torsion in 4-6 hours

Swollen, more hypoechoic

What is the sonographic appearance of scrotal torsion after 24 hours

Heterogeneous as a result of hemorrhage

What finding is considered to be diagnostic of torsion

Absence of perfusion in the symptomatic side