SCAI CHAP 9 IVUS Flashcards
(33 cards)
Q1: What two factors determine the quality of IVUS images?
Q2: What is *spatial resolution in IVUS?
Q3: What is depth in IVUS imaging?
Q4: What ultrasound frequency range does IVUS use?
Q5: What is the *axial resolution range of standard IVUS?
Q6: What is the *lateral resolution range of IVUS?
Q7: What is the typical tissue penetration depth of IVUS?
Q8: What frequency does high-definition IVUS use?
Q9: What are the two main components of an IVUS system?
Q10: What are the two types of transducer design in IVUS catheters?
A1: Spatial resolution and depth
A2: Minimum distance between two adjacent points that can be distinguished
A3: Ability to visualize the far field (tissue penetration)
A4: 20-60 MHz
A5: 20 to 150 µm
A6: 200 to 250 µm ( 0.2 to 0.25 mm )
A7: 6 to 12 mm
A8: 60 MHz
A9: Catheter with miniaturized transducer and console with electronics. IVUS catheters typically range in size from 2.9 to 3.6F (0.96-1.17 mm) and are compatible with 5F or 6F guide catheters.
A10: Mechanically rotated transducers ( usually higher resolution ) and multielement electronic phased-array transducers.
Q1: What procedure is the IVUS technique identical to?
Q2: What anticoagulation is given before IVUS catheter insertion?
Q3: Where is the guide wire introduced?
Q4: Over what is the IVUS catheter advanced?
Q5: What type of catheter pullback is performed during IVUS?
Q6: What is the purpose of the catheter pullback?
Q7: What potential risks does intracoronary instrumentation carry?
Q8: What can the imaging transducer transiently occlude?
Q9: What medication is recommended before instrumentation to prevent coronary spasm?
Q10: What is the recommended activated clotting time before catheter insertion?
A1: Percutaneous coronary intervention (PCI) catheter insertion
A2: Heparin anticoagulation
A3: Ostial aortic position
A4: Guidewire
A5: Manual or motorized pullback
A6: To provide longitudinal vessel imaging for quantitation
A7: Intimal injury or acute vessel dissection
A8: Coronary artery
A9: Intracoronary nitroglycerine (50-200 µg)
A10: Greater than 250 or 300 seconds depending on device
Q1: What imaging modality is considered a workhorse in the cath lab?
Q2: What two skills are essential for IVUS use?
Q3: What does IVUS help distinguish between?
Q4: What dimensions does IVUS accurately measure?
Q5: What pattern does flowing blood exhibit on IVUS?
Q6: What does blood echogenicity depend on?
Q7: What happens to the blood echogenicity pattern when blood flow reduces?
Q8: At higher imaging frequencies, what becomes more prominent in blood?
Q9: How is the lumen area determined on IVUS?
Q10: Which three layers of the arterial wall can IVUS visualize?
Q11: How does the intima appear on IVUS?
Q12: How does the media appear on IVUS?
Q13: What cells are present in the media layer?
Q14: How does the adventitia appear on IVUS?
Q15: Why does the adventitia produce the highest gray-level intensity?
A1: IVUS (Intravascular Ultrasound)
A2: Performance and interpretation
A3: Different types of plaque
A4: Lumen and plaque
A5: Echogenicity pattern
A6: Blood flow velocity
A7: It becomes higher intensity and coarser in texture
A8: Blood “speckle”
A9: By planimetry of the leading edge of the blood-intima acoustic interface
A10: Intima, media, and adventitia
A11: As an echodense (gray) layer closest to the transducer
A12: As an echolucent (black) ring with weak scattering
A13: Smooth muscle cells
A14: As an echodense connective tissue layer
A15: Due to greater scattering of ultrasound waves
In ultrasound imaging, “speckle” refers to the granular, grainy texture or noise-like pattern that appears in the image. It is caused by the interference of the scattered ultrasound waves from many tiny structures within the tissue, which results in a characteristic “salt-and-pepper” appearance.
It is a type of image artifact, not actual anatomical structure.
Speckle arises because ultrasound waves scatter off small tissue microstructures that are smaller than the ultrasound wavelength.
It can reduce image clarity and contrast, making it harder to distinguish fine details.
However, speckle also contains useful information about tissue texture and can be analyzed for diagnostic purposes in advanced imaging techniques.
Speckle is more prominent at higher ultrasound frequencies.
Q1: How is the gray-level appearance of plaque constituents defined?
Q2: How does lipid-rich tissue appear on IVUS?
Q3: What color or shade is lipid-rich tissue typically?
Q4: How are the borders of lipid-rich tissue usually described?
Q5: How does a necrotic core usually appear?
Q6: How is fibrous tissue characterized on IVUS?
Q7: What is the echodensity of fibrous tissue relative to adventitia?
Q8: What kind of texture does fibrous tissue have?
Q9: Does fibrous tissue cause an acoustic shadow?
Q10: How does calcified tissue appear on IVUS?
Q11: How does the brightness of calcified tissue compare to adventitia?
Q12: What acoustic phenomenon is associated with calcified tissue?
Q13: How does thrombus appear on IVUS?
Q14: How does **fresh thrombus appear on IVUS?
Q15: How does ***older or organized thrombus appear on IVUS?
A1: By brightness relative to adventitia
A2: Homogeneously hypoechoic regions
A3: Black or light gray
A4: Irregular or poorly defined borders
A5: Usually black region
A6: Moderately echodense regions
A7: Similarly bright to adventitia
A8: Heterogeneous texture
A9: ***** No acoustic shadow
A10: Highly echodense (bright white) regions
A11: Brighter than adventitia
A12: Complete distal acoustic shadowing
A13: Luminal mass with variable echogenicity
A14: Echolucent (black)
A15: Heterogeneous echodense (gray)
A, Normal wall; B, Fibroatheroma; C, Thin-cap fibroatheroma; D, Fibrocalcified plaque.
.A, Normal wall; B, Fibroatheroma; C, Thin-cap fibroatheroma; D, Fibrocalcified plaque.
EEM outside the Media
IEM inside the Media
“M” like “M”edia
The OUTER green circle in the pictures i think it is the EEM. So always identify the black area corresponding to the Media and draw a green circle at the outer Media border, this would be your EEM.
I think It is very hard to draw IEM because it is often masked by other components like necrotic core, so do not look or plan on localizeing or drawing IEM. It is very hard to recognize it , that is why we do not use it for measurements or sizing. It is very hard to delineate the borders between Media and Intima.
Fibrous cap, lipid pool and necrotic core are ALL part of the INTIMA ( I think ).
ORIENTATION
Catheter –> INTIMA ( white ) –> IEM –> Media ( black ) –> EEM –> Adventitia ( white )
Q1: Where is the guide wire positioned relative to the transducer in most IVUS designs?
Q2: What does the wire artifact look like on IVUS?
Q3: What causes shadow artifact in IVUS imaging?
Q4: What effect does shadow artifact have on visualization?
Q5: What is the ringdown artifact caused by?
Q6: What does the ringdown artifact obscure?
Q7: How is the ringdown artifact handled in electronic array catheters?
Q8: What causes reverberation artifact in IVUS?
Q9: What kind of surfaces cause reverberation artifact?
Q10: What happens to IVUS waves during reverberation artifact?
Q11: How does the IVUS transducer interpret reverberated sound waves?
Q12: How do reverberation artifacts appear on the IVUS image?
Q13: What materials can cause reverberation artifacts?
Q14: Is the ringdown artifact present in all medical ultrasound devices?
Q15: Can mechanical systems merge ringdown artifact with any other artifact?
A1: External to the transducer
A2: Gray or black shade
A3: High-density structures like calcium or stent struts
A4: Creates dark areas behind the structure, limiting visualization
A5: Acoustic oscillations in the piezoelectric transducer
A6: Near-field imaging ( high amplitude signals that obscure the near field )
A7: Removed largely by mask subtraction
A8: IVUS beam encountering two parallel strong reflecting surfaces
A9: Calcium, metal stents, guide wires, guide catheters
A10: Reflected back and forth repeatedly
A11: As deeper structures
A12: Multiple evenly spaced circumferential layers
A13: Calcium, metal stents, guide wires, guide catheters
A14: Yes
A15: Yes, with imaging sheath artifact
Ringdown artifact in ultrasound refers to a type of imaging artifact caused by
*** prolonged acoustic oscillations within the ultrasound transducer’s piezoelectric material.
Explanation:
When the transducer sends out an ultrasound pulse, it can sometimes continue to vibrate (or “ring”) for a short time after the pulse is sent.
These continued vibrations generate high-amplitude signals that interfere with the imaging of structures very close to the transducer, known as the near-field.
This causes a bright echo or “artifact” that obscures the immediate area near the transducer, making it difficult to visualize structures in that region.
In some ultrasound systems, especially electronic phased-array catheters, this artifact can be reduced or removed by signal processing techniques like mask subtraction.
In mechanical systems, it may blend with other artifacts such as the imaging sheath artifact.
**Reverberation artifact is caused by STRUCTURES around the transducer
***Ringdown artifact is caused by the TRANSDUCER
Q1: What causes nonuniform rotational distortion (NURD) in mechanical transducers?
Q2: When is NURD most evident?
Q3: How does NURD appear on IVUS images?
Q4: What is a common cause of mechanical drag leading to NURD?
Q5: What does attenuation artifact refer to in IVUS imaging?
Q6: What effect does attenuation have on ultrasound waves?
Q7: Which types of plaques cause significant attenuation?
Q8: How does attenuation affect image quality?
Q9: What causes geometric distortion in IVUS imaging?
Q10: How does geometric distortion affect the appearance of the lumen?
Q11: In which coronary artery is geometric distortion particularly evident?
Q12: What shape does the lumen appear when geometric distortion occurs?
Q13: What type of imaging plane causes geometric distortion?
Q14: Is NURD a mechanical or electronic artifact?
Q15: What is the relationship between vessel tortuosity and NURD?
A1: Variations in rotational speed due to mechanical drag on catheter driveshaft
A2: When the driveshaft is bent into a small radius of curvature by a tortuous vessel
A3: Circumferential stretching of part of the image with compression of the opposite wall
A4: Bending of the catheter in tortuous vessels
A5: Attenuation of sound waves as they pass through certain tissues or materials
A6: Decreases image quality or penetration
A7: Heavily calcified or fibrotic plaques
A8: Reduces image clarity and depth of visualization
A9: Oblique imaging planes
A10: Circular lumen appears elliptical
A11: Left main (LM) coronary artery
A12: Elliptical shape
A13: When the ultrasound beam is not orthogonal to the vessel wall
A14: Mechanical artifact
A15: Increased vessel tortuosity increases likelihood of NURD
Q1: What class recommendation do the 2021 ACC/AHA/SCAI guidelines assign for performing IVUS to define lesion severity and reduce ischemic events ?
Q2: For which types of stenting is IVUS particularly recommended?
Q3: What is the class recommendation for IVUS use to determine the mechanism of stent failure?
Q4: What is the best method to assess hemodynamic severity of ischemia across a stenosis?
Q5: Does IVUS provide direct or indirect information about lesion hemodynamic severity?
Q6: Should physiologic tests be substituted by IVUS for ischemia assessment?
Q7: In ***non-left main (non-LM) lesions, what IVUS measurement best correlates with ischemia?
Q8: What is the recommended minimum lumen area (MLA) cutoff by meta-analyses for non-LM lesions?
Q9: What is the range of MLA cutoffs reported in IVUS studies?
Q10: Does the MLA cutoff have high positive or negative predictive value?
Q11: What does a low positive predictive value of MLA cutoff suggest about its correlation with physiologic studies?
Q12: Should IVUS MLA cutoff alone be used to predict stress-induced ischemia in non-LM lesions?
Q13: Name one other lesion characteristic important in assessing hemodynamic significance besides MLA.
Q14: What is fractional flow reserve (FFR)?
Q15: Why should other lesion characteristics be considered along with MLA in assessing lesion significance?
A1: Class IIa
A2: Left main (LM) or complex coronary artery stenting
A3: Class IIa
A4: Physiologic studies
A5: Indirect
A6: No, physiologic tests are gold standard and should not be substituted
A7: ***Minimum lumen area (MLA)
A8: 3.0 mm²
A9: 2.1 to 4.4 mm²
A10: High negative predictive value
A11: Poor correlation between IVUS MLA and physiologic studies for non-LM stenoses ( if MLA below 3 for example, do not supose ffr will be likely abnormal )
A12: No, it should be avoided ( ow MLA does not necessarily predict abnormal ffr or stress induced iscemia )
A13: Lesion length, area stenosis, plaque burden, reference vessel size, or location
A14: A measurement of pressure differences across a coronary lesion to assess ischemia
A15: Because lesion characteristics other than MLA significantly affect hemodynamic significance
Q1: Does the LM artery have a high or low correlation between IVUS and FFR?
Q2: What LM MLA value is associated with similar outcomes between deferred and revascularized patients?
Q3: What happens to outcomes in patients with LM MLA < 6.0 mm² who did not undergo revascularization?
Q4: According to current recommendations, when can revascularization be safely deferred in LM lesions?
Q5: At what LM MLA value should revascularization be pursued?
Q6: What should be done for LM lesions with MLA between 4.5 and 6.0 mm²?
Q7: What type of studies should be considered for LM lesions with intermediate MLA values?
Q8: What does MLA stand for?
Q9: What does FFR stand for?
Q10: Is IVUS useful in guiding treatment decisions for LM lesions?
Q11: What is the significance of an LM MLA > 6.0 mm²?
Q12: What is the significance of an LM MLA < 4.5 mm²?
Q13: What patient group had worse outcomes without revascularization?
Q14: What is the recommended approach for LM lesions with MLA < 4.5 mm²?
Q15: Why is further evaluation recommended for LM lesions with MLA between 4.5 and 6.0 mm²?
A1: High correlation ( ** unlike non-LM arteries )
A2: LM MLA > 6.0 mm²
A3: Significantly worse outcomes
A4: When MLA > 6.0 mm²
A5: When MLA < 4.5 mm²
A6: Further evaluation with physiologic studies
A7: Invasive or noninvasive physiologic studies
A8: Minimum lumen area
A9: Fractional flow reserve
A10: Yes, it helps guide revascularization decisions
A11: Revascularization can be safely deferred
A12: Revascularization should be pursued
A13: Patients with LM MLA < 6.0 mm² who did not have revascularization
A14: Pursue revascularization
A15: Because MLA is intermediate and hemodynamic significance is uncertain
Q1: What does IVUS provide to guide lesion preparation strategy?
Q2: How are predominantly **lipid-rich plaques treated?
Q3: What type of balloon is used for predilation of **fibrotic or moderately calcified plaques?
Q4: What devices are used for plaque modification in severely calcified plaques?
Q5: What percentage of target lesions contain calcium?
Q6: How sensitive is fluoroscopy or angiography in detecting calcification?
Q7: What procedural risks increase with calcification?
Q8: What postprocedural outcomes worsen with calcified nodules?
Q9: What do calcified nodules tend to cause in stents?
Q10: Why is adequate lesion preparation critical?
Q11: What does IVUS provide about calcification severity?
Q12: What guides lesion preparation strategy according to the passage?
Q13: What types of atherectomy devices are mentioned?
Q14: What is the role of intravascular lithotripsy?
Q15: What is the difference between compliant and noncompliant balloons?
A1: Detailed plaque tissue characterization
A2: Predilation with a compliant balloon or direct stenting
A3: Noncompliant, high pressure, or cutting/scoring balloon
A4: Atherectomy devices (rotational, orbital) or intravascular lithotripsy
A5: 75%
A6: Approximately 40% sensitivity
A7: Stent underexpansion, dissection, perforation, acute lumen closure
A8: Worse post-PCI outcomes and in-stent restenosis
A9: Major stent underexpansion and protrusion through stent struts
A10: To reduce procedural risks and improve outcomes
A11: Accurate information based on a scoring system
A12: An algorithm illustrated in Fig. 9.6
A13: Rotational and orbital atherectomy
A14: To modify calcified plaques using shockwave energy
A15: Compliant balloons expand more easily, noncompliant balloons resist expansion and provide higher pressure
Q1: What imaging modality offers advantages over angiography for stent sizing?
Q2: What does IVUS help identify for stent sizing?
Q3: Compared to IVUS, does angiography tend to overestimate or underestimate lumen dimensions?
Q4: What effect does IVUS guidance have on stent diameter?
Q5: How does IVUS guidance affect angiographic mean lumen diameter (MLD)?
Q6: What is the impact of IVUS guidance on minimum stent area (MSA)?
Q7: Does IVUS guidance lead to implantation of more or fewer stents compared to angiography?
Q8: Does IVUS guidance tend to result in longer or shorter stents?
Q9: What are two common methods of angiography mentioned for stent sizing?
Q10: Why is IVUS preferred over angiography for stent sizing?
A1: IVUS (Intravascular Ultrasound)
A2: Reference segments and stent sizing
A3: **Underestimate ( that is why they say always add +0.5 mm )
A4: Results in chosing a larger stent diameter
A5: Results in greater MLD
A6: Results in greater MSA
A7: More stents
A8: Longer stents
A9: Eyeballing and quantitative coronary angiography
A10: Because it provides more accurate lumen dimension measurements
Q1: What is a major ( most important ) predictor of stent failure and adverse outcome related to lesion coverage?
Q2: How is stent length determined?
Q3: What should be the plaque burden at the proximal and distal landing zones?
Q4: What is the plaque burden expressed as?
Q5: Why should plaque burden be less than 50% at landing zones?
Q6: What should ideally be absent at landing zones to reduce stent edge dissection?
Q7: What should ideally be absent at landing zones to reduce restenosis risk?
Q8: What is the external elastic membrane (EEM) area used for in this context?
Q9: What is meant by “geographical miss”?
Q10: Why is minimizing plaque burden at landing zones important?
A1: Incomplete lesion coverage (geographical miss)
A2: Distance between proximal and distal landing zones
A3: Less than 50% plaque burden
A4: Percentage of mean external elastic membrane (EEM) area occupied by plaque
A5: To minimize risk of stent edge complications
A6: Lipid-rich material
A7: Severe calcification
A8: To assess plaque burden
A9: Failure to cover the entire lesion with the stent
A10: To reduce risk of edge dissection and restenosis
Q1: What is a powerful predictor of stent thrombosis (ST) and restenosis?
Q2: On what should stent diameter selection be based?
Q3: Where is the distal landing zone typically located?
Q4: What is the conservative approach for selecting stent diameter?
Q5: How is the stent diameter rounded in the conservative approach?
Q6: Give an example of stent sizing using the conservative approach if MLD is 3.6 mm.
Q7: What does the less conservative approach consider for stent diameter?
Q8: How is the stent diameter rounded in the less conservative approach?
Q9: Give an example of stent sizing using the less conservative approach if EEM diameter is 3.9 mm.
Q10: Why is selecting the correct stent diameter critical?
A1: Stent underexpansion
A2: Distal landing zone measurement
A3: Site of largest lumen distal to stenosis, ideally within same segment without major branches
A4: Based on minimum lumen diameter (MLD) of distal reference
A5: Rounded *up to the nearest available stent diameter *quarter
A6: For MLD 3.6 mm, select 3.75 mm stent
A7: Considers external elastic membrane (EEM) diameter at distal reference
A8: Rounded *down to nearest available stent diameter *quarter
A9: For EEM diameter 3.9 mm, select 3.75 mm stent
A10: To prevent stent underexpansion and reduce risk of ST and restenosis
The term “ringdown artifact” is used because it describes the prolonged ringing or oscillation of the ultrasound transducer material after it emits an ultrasound pulse.
Explanation:
When the ultrasound transducer sends out a pulse, the piezoelectric crystal inside continues to vibrate (“ring”) briefly after the pulse.
This continued vibration generates echo signals that “ring down” in amplitude over time, similar to how a bell rings and gradually fades.
These ongoing vibrations produce high-amplitude signals that interfere with imaging, especially close to the transducer (near-field), causing the characteristic artifact.
Hence, the artifact is called “ringdown” because of this ringing and gradual fading of the transducer’s acoustic signal after pulse emission.
