Exam 1: (condensed) Validity Testing, Mesenteric Doppler, Liver Doppler, Liver Pathologies, Liver Transplant, Renal Doppler, Renal Transplant

Gold Standard for Vascular Imaging

Angiography

Validity

Ability of a test to distinguish between who has the disease and who does not

Sensitivity

Ability of test to correctly detect patients with disease compared to the gold standard - positive sonogram with positive gold standard

Specificity

Ability of test to correctly detect patients without disease compared to the gold standard - negative sonogram with negative gold standard

Positive Predictive Value (PPV)

Probability that a positive test result reflects the actual presence of disease

Portion of patients with a positive test that have disease

Negative Predictive Value (NPV)

Probability that a negative test result reflects the actual absence of disease

Portion of patients with a negative test that do not have disease

Accuracy

Degree of closeness of a test result to the actual value

Percentage of overall correct results

Must lie between sensitivity & specificity and PPV & NPV

Reliability

Consistency of obtaining similar results under similar conditions - reflects accuracy over time

Increasing Cut-Off Values

Improves specificity

More true negatives

Decreasing Cut-Off Values

Improves sensitivity

More true positives

Celiac Artery Occlusion

Results in SMA collaterals diverting blood through gastroduodenal artery toward the liver and spleen

Replaced Right Hepatic Artery

Right hepatic artery branches off something else besides celiac artery - usually SMA

Hepatic Artery Retrograde Flow

Due to celiac artery occlusion

Blood flows towards splenic artery - RABT color pattern

Pre-Prandial SMA Doppler

Post-Prandial SMA Doppler

Common Trunk Variant

Celiac and SMA come off common trunk

Prominent IMA

Due to SMA occlusion

Acute Mesenteric Ischemia

Thrombosis of one or more mesenteric vessels

Life threatening - requires immediate intervention

Severe cramping/pain - disproportional pain

Chronic Mesenteric Ischemia

Low resistant pre-prandial doppler signals

70% occlusion of 2/3 splanchnic arteries required for diagnosis (celiac, SMA, IMA)

Epigastric pain after eating - fear of food, weight loss, decreased nutrition

Compensatory Flow

Elevated velocities in normal collateral vessels

No stenotic profile seen

Dissection

Separation of channels - flap line

To and fro flow

Median Arcuate Ligament Syndrome (MALS)

Compression of celiac axis during exhalation by median arcuate ligament

Pain relieved by inhalation

Evaluate in supine & upright positions and with inspiration & expiration

Pre-Hepatic/Inflow Vessels

Portal Vein

Hepatic Artery

Intrahepatic/Sinusoidal Vessels

Sinusoids/capillaries

Hepatocytes

Post-Hepatic/Outflow Vessels

Central Veins

Sublobular Veins

Hepatic Veins

IVC

Left Gastric Vein (coronary vein) Doppler Flow

Hepatofugal

Main Portal Vein Doppler Waveform

Monophasic continuous waveform

Hepatopetal flow (antegrade flow)

Hepatic Vein Doppler Waveform

Triphasic

Antegrade & retrograde flow - cardiac pressure changes

Hepatic Vein Doppler

S wave: ventricular systole

D wave: atrial filling

A wave: atrial contraction

Inspiration depresses systolic wave

Exhalation augments systolic wave

Valsalva diminishes pulsatility

Hepatic Artery Doppler Waveform

Hepatopetal

Low resistant monophasic pan-diastolic forward flow

Hepatic Buffer Response

When PV flow increases, HA flow decreases (post-prandial)

Splenic Vein Doppler Waveform

Hepatopetal flow

Continuous monophasic with slight respiratory variation

SMV Doppler Waveform

Hepatopetal flow

Continuous monophasic with slight respiratory variation

Portal HTN

Increased pressure in portal venous system

Not diagnosed with spectral Doppler -> diagnosed with gray scale & color

Causes of Portal HTN

Hepatitis C

Hepatitis B

Alcoholic cirrhosis

Primary Biliary Cirrhosis

Autoimmune Hepatitis

Hereditary Hematochromatosis

Schistosomiasis

Portal HTN 2D Findings

Large pulmonary vein

Collaterals

Splenomegaly

Ascites

Enlarged hepatic artery

Portal HTN Doppler Findings

Slow, hepatofugal flow in portal vein

Cirrhosis

End-stage liver disease

Cirrhosis Findings

Portalization of hepatic veins

Collaterals

Hepatofugal flow in portal vein & splenic vein

Coronary Vein Collateral

Can lead to esophageal varices

Recanalized Paraumbilical Vein

Ligamentum teres recanalizes

Courses from left portal vein to anterior abdominal wall

Hepatofugal flow

Splenorenal Shunt

Prominent veins at splenic hilum

Hepatofugal flow in splenic vein

Gastroesophageal Veins/Esophageal Varices

Originate from gastroesophageal junction posterior to left liver lobe

Due to hepatofugal flow in coronary vein shunt

High risk of rupture

AV Fistula

Arterialized portal vein flow - hepatic artery to portal vein shunting

Leads to portal HTN

AV Fistula Findings

Large anechoic spaces

Increased portal vein pulsatility & velocities

Aterialization of the Liver

Max portal vein pressure leads to increased hepatic artery flow

Cavernous Transformation

Due to chronic portal vein thrombosis

Occurs within 6 days after thrombotic event

Absent portal vein flow

Formation of new peri-portal vessels around portal vein

Hepatopetal flow within serpentine vessels

Budd-Chiari Syndrome

Hepatic vein/liver outflow obstruction

Causes increased sinusoidal pressure

Budd-Chiari Syndrome Findings

Hepatic vein thrombosis/post-sinusoidal thrombosis

Monophasic, reduced/reversed flow in portal vein

Enlarged caudate lobe

Ascites

Splenomegaly

Cardiac Cirrhosis

Liver edema caused by congestive heart failure

Portal Vein with Cardiac Cirrhosis

Pulsatile

Biphasic

Hepatic Veins with Cardiac Cirrhosis

Compromised flow - over congestion

"w" pattern

TIPS Shunt

Stent between portal vein & hepatic vein

(commonly right portal vein and right hepatic vein)

TIPS Shunt Normal Findings

No focal aliasing

Hepatofugal flow in portal veins beyond stent

TIPS Shunt Abnormal Findings

Focal aliasing

Velocity changes

Antegrade flow in right & left portal veins

Retrograde flow in hepatic vein

Developing ascites or collaterals

TIPS Shunt Occlusion Findings

Hepatopetal flow in right & left portal veins

Hepatofugal flow in main portal vein

Resistive Index

Resistance of the end/target organ

Orthotopic Liver Transplant

Whole liver is transplanted from a deceased donor

Piggyback IVC Anastomosis

Donor supra hepatic IVC attached to recipients hepatic venous confluence

Partial Liver Transplant

Right lobe for adults

Left lobe for children

Normal Post-Transplant Findings

Parenchymal changes

Biliary ducts mat appear thicker - pneumobilia

Hematoma/pleural effusion

Increased RI of hepatic artery

Hepatic Artery Thrombus

Most common vascular complication of liver transplants

Second leading cause of graft failure

Occurs within 2 weeks post-transplant

Hepatic Artery Stenosis

Common at site of anastomosis

Leads to biliary ischemia & hepatic failure - must be treated

Hepatic Artery Pseudoaneurysm

Abnormal dilation due to disruption of intimal lining

Most found at sites of anastomosis

Often mycotic

Most commonly extrahepatic due to arterial wall weakening

Can be intrahepatic due to biopsy or biliary procedures

Anastomotic Biliary Stricture

Due to donor size mismatch or fibrosis

Dilated intrahepatic ducts

Prox CBD dilation

Non-Anastomotic Biliary Stricture

Multiple, long, focal ducts

Due to ischemia, hepatic artery thrombus, chronic rejection, or sclerosing cholangitis

Signs of Liver Transplant Rejection

Abnormal liver function tests

Ascites/pleural effusions

Varices

Sepsis, fever, infection

Biliary obstruction, leakage

Splenomegaly

Right Renal Artery

Posterior to IVC and RRV

Left Renal Artery

Accessory Arteries

Branch off main renal artery or aorta

Supply small portions of renal parenchyma.

Can be single/multiple and unilateral/bilateral

If stenotic, can result in HTN

Normal Renal Artery Spectral Waveform

Rapid upstroke

Early systolic peak

2nd most common cause of renal artery stenosis

Fibromuscular dysplasia

0-59% Stenosis Waveform

60-70% Stenosis Waveform

> 80% Stenosis Waveform

Direct Renal Artery Exam

Uses velocities & RAR

Indirect Renal Artery Exam

Uses acceleration time, acceleration index, and waveform assessments

Acceleration Time (AT)

Time it takes for the to reach early systolic peak

Acceleration Index

Change in velocity divided by acceleration time

Tardus Parvus Flow

Rounded/delayed upstroke - indicates high grade stenosis proximally

100% indicative of RAS, but not always seen in RAS patients

Measured by acceleration time or acceleration index

Normal Renal Vein Doppler

Continuous pattern with mild respiratory variations

Sonographic Appearance of Renal Vein Thrombosis

Enlarged kidney

Enlarged vein with internal echoes

Lack of color fill

Biphasic/high resistant arterial signal

Indications for Renal Transplant

Diabetes mellitus (most common)

Autosomal dominant polycystic kidney disease

Glomerulonephritis

Hypertension

Atherosclerosis

Systemic lupus erythematous

Renal Artery Transplant Placement

Superficially located

Runs with the axis of incision

Hilum oriented inferiorly and posteriorly

Acute Tubular Necrosis (ATN)

Due to ischemia that develops between recipient removal to donor transplant

Common with cadaver donor kidneys

Occurs early post-op

Appearance of Acute Tubular Necrosis (ATN)

Enlarged kidney

Loss of corticomedullary boarders

Parenchymal Graft Failure Causes

Acute tubular necrosis (ATN)

Rejection

Cyclosporin toxicity

Vascular Transplant Failure Causes

Thrombosis

Stenosis

Urological Transplant Failure Causes

Obstruction

Extrinsic compression

Fluid collections

Symptoms of Renal Transplant Rejection

Sudden cessation of urine output (anuria)

Decreased urine output (oliguria)

Increased serum creatinine, protein, or lymphocytes in urine

Hypertension

Swelling or tenderness of the graft

Hyperacute Transplant Rejection

Minutes to hours

Rare

Due to faulty crossmatching tests

Completely destroys graft

Removed immediately

Acute Transplant Rejection

2 weeks - 3 months

Common in cadaver donor kidneys

Appearance of Acute Transplant Rejection

Enlarged kidney

Loss of corticomedullary boarder

Decrease in diastolic flow or flow reversal

RI > 0.8

Chronic Transplant Rejection

3 months - years

Appearance of Chronic Transplant Rejection

Echogenic kidney

Loss of corticomedullary boarders

Solid material in renal pelvis

Hydronephrosis Post-Transplant

Due to ureteral narrowing from surgery

Compresses ureter and parenchyma

Increased RI

Perinephric Hematoma

Variable echogenicity - depends on time since hemorrhage occurred

Urinoma

Urine leaking from ureteral anastomosis

Seen in first weeks post-transplant

Suspected when urine output decreases

Risk for rupture - increase quickly

Lymphocele

Surgical nick in lymphatic system

Seen 4-8 weeks post-op

Complex appearance

Can compress the kidney

Page Kidney

Compression of kidney by fluid collections

Longlasting HTN

Blunted waveforms

Increased resistance