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12 Cards in this Set
1. How do you estimate the degree of carotid stenosis?
2. What is the criteria used for carotid artery stenosis?
3. When are ratios used?
- Measurement of peak systolic velocities (PSV) and end diastolic velocities.
- Measurement of ratios (eg, ICA PSV/CCA PSV)
- Normal: ICA PSV < 125 cm/s and no plaque or intimal thickening is visible.
- < 50% stenosis: ICA PSV < 125 cm/s and plaque or intimal thickening is visible.
- 50-69% stenosis: ICA PSV is 125-230 cm/s and plaque is visible.
- >70% stenosis to near occlusion: ICA PSV >230 cm/s and visible plaque and lumen narrowing are seen.
- Near occlusion: A markedly narrowed lumen is seen on color Doppler ultrasound. With stenosis over 90% (near occlusion), velocities may actually drop as mechanisms that maintain flow fail.
- Total occlusion: No detectable patent lumen is seen on grayscale ultrasound, and no flow is seen on spectral, power, and color Doppler ultrasound.
3. Ratios may be particularly helpful in situations in which cardiovascular factors (eg, poor ejection fraction) limit the increase in velocity. In such cases, ICA/CCA ratios above 3 may signify significant stenosis.
- purely cystic lesion or a hyperechoic lesion is rarely malignant.
- isoechoic or hypoechoic lesions may be malignant.
- ill-defined borders and microcalcifications favor malignancy.
- Well-defined borders, a complete echopenic halo around a lesion, and
eggshell calcifications increase the odds that it is a benign process.
Energies of ultrasound waves
M mode < gray scale < color Doppler < pulsed Doppler
What is the typical gut signature?
Typical gut signature of hyperechoic mucosal surface straight arrow and hypoechoic submucosa open arrow
What are the causes of increased resistive index of a transplant kidney?
2. Allograft rejection
3. Renal vein thrombosis
Differentiated thyroid cancers include papillary and follicular carcinomas. The presence of microcalcifications in a thyroid nodule has a high specificity (85-95%) but low sensitivity (25-59%) for papillary thyroid cancer. Microcalcifications are not generally seen in follicular neoplasms.
Reasonable Alternative: Imaging overlap between follicular adenomas and differentiated thyroid cancers is the main reason why most solid thyroid nodules greater than a certain size are biopsied. The presence of microcalcifications is more suggestive of papillary cancer.
Waveform abnormailities in cirrhosis
Loss of normal triphasic hepatic venous waveform.
Increased portal venous pulsatility
- >50% stenosis in a SYMPTOMATIC pt.
- >60% stenosis in an ASYMPTOMATIC pt.
- Endovascular treatment is indicated in a symptomatic pt with >70% stenosis.
Failing renal transplant
- MCC of graft dysfxn within the first week posttransplant.
- Enlarged, swollen kidney with loss of corticomedullary differentiation, elevated resistive index > 0.8.
- Spontaneous recovery
RENAL ARTERY STENOSIS
- MC vascular complication of renal transplant.
- Turbulent flow with aliasing at the anastamosis
- Peak systolic velocity >250 cm/sec.
- Parvus et tardus waveform in the renal artery distal to the stenosis.
- utereral strictures form due to disruption of ureteral blood supply when performing UVJ anastomosis.
- look for perigraft fluid collections that may be compressing the allograft or resulting in hydronephrosis.
- Acute rejection is seen in the first week and thus it is hard to differentiate from ATN. Look for associated urothelial thickening and possibly regions of parenchymal infarctions.
- Chronic rejection: graft becomes small and echogenic with thinning of the cortices and sparing of the medullary pyramids.
RENAL VEIN THROMBOSIS
- surgical emergency as the transplanted kidney does not have any collaterals
- delay in dx leads to venous infarction
- ultrasound demonstrates reversal of diastolic flow in to-and-fro pattern.
- Cyclosporine toxicity has a constrictive effect on renal arterioles, resulting in decreased perfusion.
- US findings are non-specific and unremarkable with no change in RI or renal size.
1. What findings indicate tips dysfunction?
2. how are patients with tips followed up?
3. What are causes of tips dysfunction?
4. What are grayscale findings of tips dysfunction?
5. What are color findings of tips dysfunction?
6. What is a normal portal systemic gradient?
7. What are causes of tips thrombosis?
8. how are tips occlusion treated?
1. Recurrence of symptoms -- enlarged varices or recurrent ascites are the best indicators for TIPS dysfunction.
2. Baseline ultrasound after the procedure then at 1, 3, 6, and 12 months after the TIPS procedure, followed by annual examination.
3. Neointimal hyperplasia (chronic), thrombosis(?bile leak), technical error.
-filling defects in the stent
-velocity gradients across the stent associated with turbulence
-marked increase or decreasing shunt velocities
-changes in portal venous flow direction
-presence of new ascites or varices.
5. Doppler findings of TIPS dysfunction:
-main portal venous velocity or shut velocity < 50 cm/s
-shut velocity > 150 cm/s
-change in velocity (increase or decrease) from baseline of greater than 50 cm/s.
6. Portal systemic gradient should be less than 12 mmHg for bleeding esophageal varices. The portal systemic gradient should be less than 8 mmHg for resolution of refractory ascites.
-EARLY: Bile leak
-LATE: Neointimal hyperplasia
8. Occlusions are treated with catheter directed or mechanical thrombolysis and stent graft revision with angioplasty or stent.
Portal vein pulsatility
Characterized as the ratio between minimum and peak PV velocities
Pulsatility indices of >0.5 are routinely seen in healthy adults, particularly thin patients
Severely pulsatile flow (minimum velocity near zero, or reversed) indicates pathology:
Predominantly found in patients with severe right heart failure
Other causes of elevated R heart pressure:
Pericardial cyst, effustion
R atrial tumor
Portal vein-hepatic vein fistula (rare)
Tardus parvus waveform
- Acceleration time (AT) > 100 msec.
AT = time from start of systole to peak systole
Increased diastolic flow, with RI < 0.5