CT Chapter 7 Flashcards
1
Q
How many high-grade luminal stenoses ( >70%) are present?
A
1
- High-grade stenosis of the distal RCA (small arrow)
- distal to origin of the PDA, therefore it is called the “right posterolateral branch (RPLB)”
- Second plaque
- calcified and non-calcified plaque that is not a high-grade stenosis
2
Q
Describe the findings and next step:
- 58 year old with history of HTN referred for CCTA with 3-month history of episodic chest burning unrelated to exertion
A
Myocardial bridging - Reassurance
- The reformats initially appear to demonstrate a large, bulky, non-calcified plaque in the proximal LAD
- However, the short axis view reveals segment to be buried within the myocardium
- Curved MPR –> typical appearance of these intramyocardial vessels
3
Q
What is one CCTA predictor of post-procedural MI in patients undergoing elective PCI?
A
Plaque Attenuation
- volumes of low and moderate density plaque attenuation are larger in patients suffering from post-procedure myocardial injury
- Likely causative roles:
- Distal plaque component embolization
- higher lipid laden plaque components
4
Q
What type of post-processing methods were used to generate the reformatted image shown below?
A
Multiplanar reformatting and thin slab MIP (5 mm)
- helps to obtain a LA projection of the RCA
5
Q
What is the best acquisition parameters for CAC?
A
- Axial
- Prospective ECG triggered
- at 120 kVp
- Mid-late diastole
- 2.5-3.0 mm slices
-
medium-sharp reconstruction filter kernel without edge enhancement
- provides moderate image noise in low-dose acquisition protocols
6
Q
What is one major limitation of volume rendered images?
A
degree of stenosis cannot be determined by these images alone
7
Q
What patient is CAC most appropriate for?
A
- Asymptomatic
- Intermediate 10-year ASCVD
8
Q
What parameter allows differentiation between the two?
- total occlusion
- high-grade, but still-patent stenosis
A
Length
- > 9 mm –> complete occlusions
- CT read:
- completely thrombosed LAD
9
Q
Describe the view and findings:
A
- Axial, Horizontal Long Axis
-
Mitral annular calcification
- RCA calcification (single arrow)
10
Q
Why is stent imaging currently not recommended?
A
- Beam Hardening Artifact
- Blooming Artifact
11
Q
What is the only appropriate imaging of coronary stents?
A
- Asymptomatic
- LM stent ► 3.0 mm
12
Q
Describe the findings:
A
Vein Graft (proximal anastomosis)
13
Q
In the evaluation of a stent for in-stent restenosis, how does the CT density (HU value) within the stent lumen compare to that of the segment proximal to the stent if the stent is occluded?
A
Lower
- thrombus and/or intimal hyperplasia (intimal tissue) are hypodense materials –> decreased CT density
14
Q
Describe the findings:
A
15
Q
What is the role of CCTA as it pertains to evaluating for ischemic heart disease in the setting of heart failure?
A
May offer a valid alternative to invasive angiography in diagnosing ischemic heart failure in patients with reduced EF
- 93 patients with dilated CMP (uncertain etiology)
- CAD prevalence: 46%
- CCTA:
- 90% sensitivity
- 97% specificity
- 100% of 3vCAD/LM were correctly identified
16
Q
What is the best interpretation of the findings:
- Cross-section of non-calcified atherosclerotic plaque in the LMCA
- Low density region within this plaque displays attenuation < 50 HU
A
No conclusion can be drawn from these specific numbers
- plaque densities vary with scan conditions
- absolute HU attenuation is not necessarily indicative of a certain plaque type
17
Q
Describe the findings:
A
Coronary Sinus
- coronary sinus is the distal-most portion of the great cardiac vein
- located in the posterior portion of the left AV groove
- great cardiac vein + tributaries (from lateral and posterior cardiac veins –> coronary sinus (drains into RA)
18
Q
What is the overall diagnostic accuracy of cardiac CT for depicting in-stent restenosis in this stent?
- 52 year old male with h/o PCI and recurrent chest pain
A
98%
- CT provides excellent evaluation of ostial stents
- Evaluation of LMCA stents, without extension into major side branch –> 98% accuracy
- side branch stenting –> 83% accuracy
19
Q
Describe the findings and most likely finding on coronary angiorgram
A
Occlusion in LCFx territory
- CT findings:
- regional thinning of the posterolateral wall of the LV
- characteristic of chronic infarct
- Cornary angiogram:
- occlusion of OM or PLB of CFx
- occasionally can be due to distal occlusion of large RCA
20
Q
What are the current recommendations for serial calcium scans?
A
Not recommended
- due to:
- uncertainty regarding its benefit
- variability of results from scan-to-scan
21
Q
Describe the findings:
A
??Conus branch??
22
Q
Describe the CT scan protocol/view:
A
Oblique MIP of the RCA
23
Q
Describe the RCA findings in this image:
A
Cardiac Motion Artifact
- likely due to irregularity of HR
- Internal mammary artery is not affected –> rules out breathing artifact
24
Q
What situation would produce respiratory motion artifact but not necessarily affect the appearance of the chest wall?
A
Isolated diaphragmatic motion
25
Describe the findings:
**ARCAPA**
* anomalous origin of right coronary artery from the pulmonary artery
* in these cases, extensive collateral circulation from the L-to-R develops to ensure delivery of oxygenated blood to the myocardium subtended by the RCA
* LAD is markedly dilated as a compensatory mechanism to supply collaterals to the RCA
26
Why is the RCA not seen in the posterior groove (arrow)?
**Left dominant circulation**
* PDA is seen to arise form the CFx
27
What is one current limitation or considered an "uncertain" indication in cardiac ct?
What are common appropriate indications?
**myocardial viability assessment]**
* Evaluation of pulmonary vein anatomy prior to AF ablation
* Coronary vein mapping prior to placement of Bi-V pacemaker
* Localization of CABG grafts prior to redo cardiac surgery
28
Describe the lumen obstruction in the proximal LAD
**Diffuse calcification with mild lumen narrowing**
* CCTA --\> diffuse calcification
* Angiogram --\> mild lumen narrowing
29
Describe the findings
**SCAD**
* symptoms classically start immediately following strenuous exercise or exertion
* Both CCTA and LHC may be unremarkable given the microscopic sized intimal tear or intramural hematoma
* Diagnosis --\> IVUS or OCT
* Treatment --\> usually conservative
30
What is the clinical significance of the finding present in this image from a patient scheduled for coronary bypass surgery?
**It may alter the surgical approach to the sternotomy**
* Patient already had a CABG:
* sternal wire seen surrounding the sternum
* SVG is seen coursing directly behind the midline sternum --\> along the wall of the RA
* SVG is at risk of being transected during repeat sternotomy
* CT findings:
* PPM leads in RA and left lateral wall (BiV)
31
Describe the findings
and
best ways to optimize the image?
* CT findings:
* 4 mm MIP
* Mixed calcified and non-calcified plaques in the LAD and LCx distributions
* Image optimization:
* Thinnest slice possible --\> reduces blooming artifact
* Sharp kernel reconstruction --\> provides best spatial resolution
* Wider window width --\> reduces volume averaging artifact from calcium
\*\*\*\*\*Smoother reconstruction kernel --\> would not reduce blooming artifact from calcified lesions
32
Describe the findings
**SA nodal artery**
* CT findings:
* thin-slab MIP
* most common course of SA node
* 60% - RCA
* 40% - CFx
* supplies arterial blood to the area of the crista terminalis in the RA where the SA nodal complex resides
33
Describe the view and findings
Axial - Thin slab MIP
34
Describe the findings
* Severe coronary calcification throughout
* LM and LAD
* do not show any luminal stenosis
* RCA
* severely calcified
* **high-grade luminal stenosis proximally**
35
What is the threshold applied for which pixels with a CT value above this will represent coronary calcification?
**130 HU**
36
Describe the findings
* CT image:
* 3D volume rendered image of RCA
* Anomalous origin of the RCA above the SinoTubular junction
* no significant ischemic consequences have been reported with this anomaly
37
Describe the findings
**LAD is occluded proximally**
38
How does CCTA compare with myocardial perfusion scintigraphy in predicting subsequent cardiac events if both are normal?
**Equally predictive (or "have equal prognostic value")**
* survival analyses demonstrate comparable risk stratification for:
* CCTA \<-- anatomic CAD
* MPI \<-- functional perfusion
* anatomic and functional measures were synergistic for the prediction of death or MI
* plaques composition was an important variable for predicting outcomes
39
Describe the findings:
* LM
* high-grade stenosis
* Proximal LAD
* mild lesion with positive remodeling
40
Describe the findings and expected coronary anatomy
* CT findings:
* **LV apical thrombus**
* Coronary anatomy (expected)
* **LAD occlusion**
* recent anterior infarction, as apical segments are supplied by LAD
* no associated wall thinning to suspect old, chronic infarction
41
Based on this image, the previous coronary bypass procedure most likely utilized which of the following blood vessels?
**Two arterial grafts (IMA) and at least one vein graft**
* there are no vessels in the chest wall adjacent to either border of the sternum --\> both IMA's have been used as arterial grafts
* one vein graft anastomosis (in a somewhat atypical position) can be seen
42
Describe the findings
**Non-calcified plaque with positive remodeling**
* low attenuation signal adjacent to the contrast enhanced lumen
* "**positive remodeling**"
* diameter of contrast enhanced lumen (artery) + non-calcified plaque --\> larger than proximal and distal reference segments
* outward expansion of the plaque
* can occur early in the atherosclerotic process
43
Describe the findings
**Both the stent and raminder of the vessel appear to be free of significant stenoses**
* 3.5 mm diameter stent in the proximal LAD --\> patent contrast-enhanced lumen without in-stent restenosis or significant beam hardening artifacts
44
Describe the findings
Short axis
45
Describe the findings:
**RCA stent - not able to be assessed**
* image quality is degraded by motion artifact
46
What procedure is being performed based on the measurement shown?
**TAVR**
* important measures:
* aortic annulus - to - LMCA and RCA ostia
* aortic root dimensions
* sinus of Valsalva
* sino-tubular junction
\*\*\*\*cases of MI secondary to prosthesis deployment across the coronary ostia have been reported
47
Describe the prognostic value of:
* absence of plaque and stenosis on CCTA
extremely low risk of death - **\< 1% mortality at 5+ years of follow-up**
* mortality-free survival begins to decrease with the presence of any degree of plaque
* worsening stenosis severity and number of vessels involved predict a further reduction in survival
48
What is the recommendation for CCTA in asymptomatic patients?
not considered appropriate
49
Describe the findings
**distal LCFx**
50
What is another name for partial volume averaging artifact?
Blooming artifact
51
Describe reproducibility of calcium scores
**better for high calcium scores**
* low scores --\> interscan variability is rather high
* one of the reasons follow-up testing is not routinely recommended
52
What patient is CCTA recommended before?
* noncoronary cardiac surgery
**Intermediate pre-test probability**
* 45 year old with HTN and tobacco abuse
53
Describe how key differences between CCTA and coronary angiogram can lead to discrepant findings?
* lower **spatial** and **temporal resolution** of CCTA
* **reference site selection** may greatly influence diameter stenosis
* invasie angiography may not appreciate diffuse disease in a segment
* selection of a reference site at a "disease-free" site may differ among these modalities
* angiography may **underestimate the minimum lumen diameter** because of its simple two-dimensional display
54
Describe the findings
Axial view
55
Define positive remodeling
* diameter of contrast enhanced lumen (artery) + non-calcified plaque --\> larger than proximal and distal reference segments
* outward expansion of the plaque
* can occur early in the atherosclerotic process
56
Describe the findings and diagnosis
* CT image:
* curved MPR (top)
* curved MIP, 3 mm thickness (bottom)
* CT findings:
* SVG-OM graft
* **stenosis in the native artery distal to the coronary anastomosis**
57
In a patient who has four venous bypass grafts in total, which graft-vessel will typically arise from the topmost (most cranial) aortic anastomosis?
* LAD
* Diagonal
* OM
* PDA
**OM**
* topmost graft is usually the graft to the CFx territory
* otherwise, grafts would have to cross over each other
* RCA graft
* usually the one with the most caudal anastomosis (closest to the aortic valve)
58
What is the prinicipal additional use of CT in this context?
* 33 year old male undergoing CTA to assess the size of his ascending aortic aneurysm prior to surgery
**Obstructive CAD**
* particularly advantageous in patients presenting with large AAA --\> difficult or time-consuming to evaluate the coronary anatomy using invasive angiography
* coronary angiography is contraindicated in setting of dissection
59
What is the recommendation for CCTA in perioperative risk assessment?
**Not recommended**
* perioperative risk assessment for non-cardiac surgery in patients **without active cardiac conditions** is considered **inappropriate or uncertain**
60
What is the sensitivity and negative predictive value?
* no known CAD
* 64-slice CCTA
**High sensitivity and Negative Predictive Value**
61
Describe the graft findings
**1 LIMA (to LAD) and 2 SVG's**
* Bypass grafts can be evaluated easily on CCTA due to:
* large size
* lack of motion (compared to native vessels)
62
Describe the findings:
**native RCA with partially calcified plaque**
* multiplanar reformat (MPR)
* can be distinguised from CFX:
* course adjacent to right ventricle/atrium in right-sided AV groove
* groove has less contrast opacification than is present in the LV/atrium in the left-sided AV groove
63
What is the SCCT recommendations for reporting overall technical quality?
**required**
* guidelines call for required reporting of the overall technical quality of the scan
* Recommended grading system:
* excellent
* good
* average
* poor
64
Describe the findings:
**calcification of RCA**
65
Describe the findings and next best step:
* 59 year old male without history of chest pain, CHF with diffuse, severe LV dysfunction with moderate MR
* suspected of having alcoholic cardiomyopathy
**Assess myocardial ischemia and viability**
* etiology of cardiomyopathy is probably CAD rather than alcohol
* CT findings:
* severely calcified and diseased RCA
66
Describe the findings:
**Occluded LAD**
* occlusion is likely recent --\> positive remodeling is present within the occluded vessel segment
67
What is the recommendation for CCTA?
* LBBB
* Chest Pain
* Low-intermediate risk profile
**Appropriate**
* ideal test for symptomatic + LBBB + low-intermediate risk
* LBBB does not interfere with ECG gating during CCTA
68
What is the recommendation for CCTA in:
* detection of native coronary vessel stenosis
* symptomatic
* prior CABG
**Low positive predictive value (PPV) for predicting obstructive CAD**
* due to small diameter and frequent severe calcification
* leads to:
* low rate of evaluable arteries
* high rate of false positive findings (severe calcification)
69
Describe the findings:
**Coronary aneurysm - Kawasaki's disease**
* Post-inflammatory changes, possibly viral in origin
70
What post-processing technique utilized to visualized the coronary artery?
**Curved MPR**
* evident from the fact that the entire vessel course is displayed on one image
* which is typically not possible with other display modes because of the multiplanar course of coronary arteries
* should be used with caution --\> processing artifacts are not infrequent --\> findings should be **confirmed with axial image sets**
71
Describe the findings:
**Partially calcified, non-obstructive plaque**
72
When evaluating the coronary arteries on CCTA, what image display methods result in the highest diagnostic accuracy?
**Axial source images + Oblique MPR**
* Accurately classified vessels + Accuracy for detecting stenosis
* **Axial** - **99%** and **88%**
* **Oblique MPR** - **99%** and **91%**
* Oblique MIP - 94% and 86%
* Curved MIP - 94% and 83%
* Curved MPR - 93% and 81%
* VRT - 91% and 73%
73
Describe all of the findings in this lesion:
* Non-calcified plaque
* Positive remodeling
* Misalignment / step artifact
* thin line extending through the dataset at the level of the lesion
74
What are the differences between coronary calcium score in:
* African American men
* Caucasian men
* **Lower in African-American**s
* Higher PPV in AA's
75
Describe the findings:
**Old-LAD territory infarct**
* CT findings:
* thinning of the apical wall
76
Describe the findings:
**Anomalous LCFx arising from the right coronary sinus**
* traveling posterior and inferior to the aortic root
* benign course --\> not expected to cause hemodynamic compromise
77
In the evaluation of a stent for in-stent restenosis, how does the CT density (HU value) within the stent lumen compare to that of the segment proximal to the stent if the stent is patent and has no restenosis?
**Higher**
* due to partial volume averaging from stent struts
* value of lumen + dense stent material --\> increased CT density
78
What is the image view?
What are the imaging findings?
* Oblique reconstruction of RCA
* **High-grade luminal stenosis of proximal RCA**
* very slight misalignment artifact in the mid-RCA
79
What reconstruction processing will help evaluate coronary artery stents concerning for restenosis?
**Sharp reconstruction kernel**
* increased the spatial resolution
* at the expense of higher image noise
80
What are post-processing techniques that will lead to decreased spatial resolution?
* increased collimation
* increase of reconstructed slice thickness
81
What effect does the use of very thin reconstructed slices have in CCTA?
**Improving Z-axis resolution = improved spatial resolution**
* z axis resolution = resolution in the cranio-caudal dimension
82
Describe the benefit of thin slice reconstruction in CCTA
Improved Z-axis resolution (spatial resolution)
* z-axis resolution matches the x and y dimension resolution (**"isotropic resolution"**)
* image can be viewed in planes other than x/y (axial) without loss of image quality
* datasets can be reconstructed in any abitrary plane without loss of image quality
83
Describe the differences in post-processing reconstruction
* MPR (off-axis) reconstruction from **thick (5mm) axial slices**
* **Low** spatial resolution
* MPR (off-axis) reconstruction from **thin (0.67 mm) axial slices**
* **High** spatial resolution
* **Isotropic resolution**
84
What plaque characteristics are associated with risk of ACS?
* Low HU attenuation ( **HU \< 30** )
* Positive remodeling
* Spotty calcification
\*\*\*\*\***Dense circumferential calcification --\> more common in stable patients**
85
Describe the findings:
**RCA stent**
86
Describe the findings:
**"Napkin ring" sign**
* **bright rim surrounding a thrombotic lumen** of the culprit coronary lesion
* caused by rim of contrast around the acute thrombus within the lumen
* may be seen in up to 25% of patients presenting with ACS
* generally not described in lesion associated with stable chest pain syndromes
87
Describe the findings:
1. SVG
2. SVG
3. LMCA
* 1 and 2 are common locations for SVG as they course anterior to the PA to the anterior and lateral surface of the LV
* 3 is a common location of the LMCA
* LAA can be seen in partial volume, which is another clue this is the LMCA
88
Describe the image view and findings:
* Curved MPR
* **Ostial RCA stent + severe obstructive disease distally**
\*\*\*\*\*Findings should be confirmed on axial images to ensure diagnostic and stenosis accuracy
89
Describe the image view and findings
* Curved MPR
* **Right posterolateral branch**
* careful inspection demonstrates partial visualization of the true PDA (broken arrow)
90
Describe the findings:
**LIMA**
* LAD visualized in the anterior interventricular groove
* LAD would not be visualized if RIMA were in view given LV orientation
91
Describe the findings:
**SVG-Diagnoal and SVG-OM1**
* 2 separate SVG's coursing anterior to the PA
* No evidence of motion or respiratory artifact on this image
92
Describe the image view and dominance pattern
* Axial, MIP (5 mm)
* **Left dominance (supplied by CFx)**
* ****small arrow --\> artery of the diaphragm
93
Describe the findings:
**Significant stenosis of a SVG**
94
What is the prognostic value of coronary imaging with CCTA?
* provides prognostic value independent and incremental to clinical risk factors in patients presenting with chest pain
* Non-obstructive plaques --\> increased risk for future cardiac events
* **Normal coronary arteries --\> 100% event-free survival**
95
Describe the findings:
**Non-obstructive, calcified plaque of RCA**
96
What are the components for calculation of the "Agatston Scroe"?
**Peak density of calcified plaque**
and
**Area of the calcified plaque**
97
Describe calculation of the Agatston score
Peak density of calcified plaque x Area of calcified plaque
* for each calcified lesion in each cross-sectional image, the area of the lesion is multiplied by a coefficient that is derived from the peak density
* Peak Densities --\> Coefficient
* 130-199 --\> 1
* 200-299 --\> 2
* 300-399 --\> 3
* \> 400 --\> 4
98
What are factors that affect visibility of the stent lumen?
* scanner technology
* spatial and temporal resolution
* stent size
* large vs. small diameter
* stent type
* material and strut thickness
99
How many coronary segments are contained in the SCCT coronary artery segmentation model?
**18 - segment model**
100
Describe the findings:
**Papillary muscle calcification**
101
Describe the findings:
**Myocardial Cleft**
* myocardial clefts or fissures are commonly seen in the basal inferior wall of the LV and the mid-to-apical segments of the interventricular septum
* probably congenital --\> no clinical or prognostic significance
102
Which of the following statements is true regarding CAC?
* Coronary calcification frequently occurs in the absence of coronrary atherosclerosis
* CAC = 0 excludes the presence of any CAD
* Extensive coronary calcification is associated with a low risk of MI
* Repeat CAC is not considered appropriate in patients with prior CAC \> 0
**Repeat CAC is not considered appropriate in patients with prior CAC \> 0**
* repeat testing 5 years after initial testing is of uncertain utility
* prior non-zero score --\> no indication for re-testing
103
Where does the internal mammary artery (L and R) most commonly originate?
**LIMA --\> Left subclavian artery**
and
**RIMA --\> Braciocephalic (inonimate) artery**
104
Describe the view and findings:
* Double-oblique reformat
* RVOT and MPA are clearly visible
* vessel traveling with malignant course
* **RCA from left coronary sinus**
105
What is the specificity of CCTA for predicting lesions with FFR « 0.80 during invasive angioraphy?
**Poor ( 15% - 49% )**
106
What makes CCTA highly reliable in ruling out coronary stenoses in selected paients?
**High negative predictive value (NPV)**
107
What is true regarding semi-automated lumen contour detection algorithms vs. expert assessment for CCTA?
**Similar performance between the two**
* automation reduces user input --\> more reproducible
108
How dose CCTA compare with invasive angiography in estimating stenosis severity?
**+/- 25% with current CT scanner technology**
109
What is the positive predictive value for CCTA for prediction of obstructive CAD?
**~50% at best**
110
Describe the difference between quantitative coronary angiography (QCA) and visual assessment?
QCA typically reports **10-20% lower percentage points** than visual assessment
* 50% coronary stenosis by QCA --\> correlates well with FFR \< 0.8
111
Describe the findings:
* **RI - High-grade stenosis (subtotal stenosis)**
* LM - mild calcification distally
* LAD - occlusion cannot be confirmed
* appearance is more consistent with the vessel simply falling out of the image plane
112
Describe the findings:
**"Jump" graft to LAD and Diagonal**
113
Describe the image view
**Curved MPR**
* plane of the image follows the centerline of the vessel
* most significant clue to the answer is the fact that the graft and native coronary runoff are seen throughout their entire course encompassing the entire width of the image
114
What are the following for pitch \< 1.0?
* Image characteristics
* Image quality
* Image characteristics
* XR beams **overlap**
* certain tissue is **exposed to radiation more than once** per scan
* Image quality
* **High SNR**
* **Increased radiation exposure**
115
What are the following for pitch \> 1.0?
* Image characteristics
* Image quality
* Image characteristics
* XR beams are **not contiguous**
* gaps in between XR beams
* Image quality
* **Low SNR**
* **Decreased radiation exposure**
