Cardio NM Flashcards
Appropriateness criteria
Chest pain
Anginal equivalent - - dyspnea, worsening effort tolerance
No symptoms - - risk for cardiovascular events
Low–age-specific risk below average, 10 year abs risk for CHD <10%
Moderate - - average or above average, 10-20%
High - - >20%
MPI appropriate
Intermediate and high pretest probability of CAD (>11%)
To exclude CAD
Exercise ECG not possible
Abnormal baseline ECG
At least one risk factor prior to high risk surgery
Agatston score for coronary calcium
<100 - - MPI inappropriate
>400 - - MPI appropriate
3 months after ACS
MPI not indicated unless no prior angiogram
MPI patient preparation
Fast 4h
No coffeine 12h
Check sugar before stress if DM
Avoid heavy meal
Hemodynamically stable 48h
Stop for 3 T1/2 - nitrates, beta blockers, anti calcium - - reduce incidence of ischemia
Stop for 5 T1/2 methylxanthine
MPI for assessment ischemia and therapy effectiveness
Continue cardiac medications
MPI pregnancy
Fetal absorbed dose higher in early stages
2 day protocol
Stress first
Lactating - - no
Stressor exercise
First choice if suspected or known CAD
Goal - to reach 85% of predicted max (220-age)
Continous monitor
Bicycle - - quadriceps fatigue - - stop before
Not if: lung, peripheral vascular, musculoskeletal, neuro disease, poor motivation
Rate pressure
Heart rate * systolic BP = double product = METS
>25000 mmHg/min - - good level of exercise
>30000 mmHg/min - - excellent level
Reasons to fail exercise
Low tolerance
Poor motivation
Arthritis
Lung disease
Peripheral vascular disease
Beta blockers
Angina
Arrhythmia
Cardiac insufficiency
Stress test injection
Tracer injected close to peak exercise - - continue exercise for 1-2 min
Vasodilators mechanism
Induce myocardial hyperemia by Adenosine receptors independent of myocardial oxygen demand
Indication: inability to exercise and LBBB
Consider if ACS and unstable Angina stable for 48h
Regadenoson and COPD
can be used if not actively wheezing.
If severe COPD - - inhaled bronchodilator prior to tracer admin
Vasodilators Combi with low level exercise
Reduce flashing, dizziness, nausea, headache, hypotension
Reduce bowel activity - - better image quality and target-to-background ratio
Not for LBBB and pacemaker
Adenosine
direct coronary arteriolar vasodilation through A2a receptor
3.5-4 fold increase myocardial blood flow
Peak vasodilation 1-2 min after start, T1/2 10 sec
Adenosine injection
Infusion or syringe pump
2 separate IV lines or 1 line with dual port Y connector
Continuous infusion 4-6 min
1 min 50 microg/kg/min - - 75, 100, 140 at 1 min interval
Tracer after 140 microg/kg/min at 2-3 min, infusion continue for 2-3 min
Adenosine side effects
Minor side effects 80%
Flushing 35-40%
AV block 8% self limiting
ST depression >1 mm5-7% - - true ischemia
AFib within several min
Convulsive seizures
Cerebrovascular accidents
Adenosine
Patient preparation
Fast 4h
No coffeine 12h
Nitrates, beta blockers, anti Calcium stop
Regadenoson
Agonist of A2a receptor
10 fold lower A1
Weak A2b and A3
Max plasma concentration 1-4 min
Manual injection, large catheter
0.4 mg regardless of weight in 5 ml
Slow bolus 30s
10s flush 5-10 ml saline
Tracer within 2 min
Side effects: shortness of breath, headache, flushing
rhythm abnormality 26%, headache 29% resolves in 30 min
No problem with bronchospasm
Regadenoson + Aminophylline
50-250 mg slow IV over 30-60 sec at least 1 min after tracer
Indication:
Systolic BP <80
Symptomatic persistent AV block
Other Arrhythmia
Wheezing
ST depression >2 mm + chest pain
Pallor, cyanosis, cold skin
Dipirydamole
Indirect vasodilator - - prevents reuptake and deamination of adenosine - - 3.8-7 fold increase blood flow - - hyperemia for 50 min
Peak vasodilation on 6.5 min
T1/2 30-45 min
Excrete in bile
Infusion pump or manual injection
Continuous IV 0.56 mg/kg/min over 4 min
Tracer 3-5 min after
Dipirydamole
Side effects
Chest pain > AV block > ST changes
Aminophylline at least 3 min after tracer (not in seizure)
Dobutamine
Sympathomimetic
Beta1 and beta 2 stimulation
Increase oxygen demand - - increase regional blood flow
Infusion pump, 2 separate IV or 1 with Y-connector
Start at dose 5-10 microg/kg/min
3-5 min interval 20, 30, 40 microg/kg/min
Tracer when HR >85% of predicted
Continue for 2 min after tracer
Fast 3h
Stop nitrates, beta blockers, anti Calcium
Atropine
May add atropine 0.25 mg IV to dobutamine if HR doesn’t reach 85%
Possible difficulties driving in 2h after atropine due to reduced ocular accommodation
Contra: narrow angle glaucoma, obstructive uropathy (incl bladder neck obstruction by BPH), AFib with uncontrolled HR, obstructive GI disease or paralytic ileus
Dobutamine side effects
Ischemic ST depression in 1/3 patients
Severe - - IV esmolol 0.5 mg/kg over 1 min or metoprolol 5 mg
Palpitation > Significant SVT or VT
Dobutamine indication
Only patients who can not undergo exercise stress and have contraindication to vasodilator (bronchospasm)
Thallium 201
Analog of K - - Na/K ATPase pump - - cytosol
No K in scar
T1/2 73.1h
Cyclotron
Electron capture
68-82 keV X-ray 88%
135 and 167 keV gamma 12%
First pass extraction 85%
Cardiac uptake 3%
Thallium dose
74-111 MBq prior to peak exercise or at peak pharm vasodilation
SPECT 10-15 min later
Redistribution (rest) 2.5-4.0h later
Reinjection 37 MBq or rest at 18-24h
Thallium uptake
Proportional to perfusion
Prolonged retention depends on viability
Uptake in lung - - lung/heart ratio >45 - - severe and multivessel CAD
Thallium redistribution
Nonuniform clearance from myocardium
Slower clearance from areas of ischemia and more rapid from areas with normal perfusion
Occurs over several hours after administration
Thallium limitations
Long T1/2 - - high radiation burden to kidneys
Low injected activity - - suboptimal in obese
Low energy emission - - significant scatter and attenuation by soft tissue - - low resolution
Tc Sestamibi vs tetrofosmin
Lipophilic cation
Retain in intact Mitochondria - - viable myocytes
T1/2 6h
On site labeling
Isomeric transition - - 140 keV - - ideal for gamma camera
First pass extraction 60%
Cardiac uptake 1.5% vs 1.2%
Excretion biliary 80% vs biliary 50%, renal 50%
Protocols
Two day
350-700 MBq/study
>113 kg or BMI >35 or big breast - - 666-1110 MBq each day
One day
250-400 MBq (1/4 of total activity) first injection
3/4 of total activity second injection
3:1 ratio of activities + 2h delay = 4:1 ration no delay
Early post exercise image - - increase detection of post ischemic wall motion impairment
MPI timing
Tc advantage
Higher energy - - less attenuation and scatter - - better quality images
Shorter half life - - higher activities - - better counting statistics
Tc disadvantage
Splanchnic uptake and excretion higher than Tl - - worse interpretation of inferior wall
Tracer molecules remain within myocytes - - 2 days for optimal stress and rest images
Uptake is less avid than Tl
Radiation exposure to staff is higher
Myocardial stunning
Persistent LV contractile dysfunction despite restoration of perfusion
Resolve within 30 min
Normal perfusion, poor contraction
FDG uptake
Gating
R-wave has to be positive and at least 3 fold higher that other positive waves
Heartbeat is divided into 16 temporal frames and bins
Exercise induced ischemia
ST depression
MPI rrhytm abnormalities
Arrhythmia - - acquisition times prolonged, loss of accuracy
Regular brady/tachy - - influence LVEF and volume values
Number of rejected beats limited to <25%
Beat length acceptance window 20%
Irregularly Irregular rhythm - - no gating
Short axis
Horizontal long axis
Vertical long axis = sagittal
Myocardial ischemia
Hypoperfusion (cold defect) on stress
Myocardial infarction
Hypoperfusion on rest-stress perfusion and decreased uptake with metabolic imaging
Transmural infarction
All layers necrosis
High sensitivity MPI
Subendocardial infarction
Only muscle adjacent to endocardium
Lower sensitivity MPI
Myocardial scar
Hypoperfusion stress and rest
Hybernating myocardium
No perfusion on rest, poor contraction
Improved perfusion on delayed Tl reinjection
Increased uptake by FDG mismatch with reduced uptake on MPI
Normal
Ischemia
Infarction
Ischemia and scar
Reverse redistribution
Rb82-chloride PET CT
K analog - - Na/K ATPase pump
T1/2 75 sec, Sr-Rb generator electron capture, eluted with saline every 10 min
30-60 mCi for each
Total study 30-45 min, stress scan 6 min
Extraction fraction 65%
Good image quality
Pharm
1.48 MeV, positron range 8.6 mm
N13 ammonia PET CT
Ammonium ion trapped in myocyte by glutamine reaction
T1/2 10 min, cyclotron on site
740 MBq - - inject <30 sec
Delay 1.5-3 min prior to image, stress scan 10 min
Extraction fraction 83%
Excellent image quality
Pharm or exercise
0.49 MeV, positron range 2.5 mm
Image just before injection - - input function - - measure blood flow
Lateral wall uptake diminished
CFR (coronary flow reserve) threshold 2.74
F18 Fluripidaz PET CT
Pyridaben analog - - inhibit mytochondrial complex 1
T1/2 109 min, cyclotron
222-370 MBq
Stress scan 5-15 min
Extraction fraction 94%
Excellent image quality
Pharm or exercise
0.25 MeV, positron range 1.0 mm
Rapid uptake, slow washout
Assess myocardial blood flow
Overcome PET limitations
O15 water gated PET CT
T1/2 125s , cyclotron on site
370-1110 MBq
Stress scan 6 min
Extraction fraction 100%
Tissue extraction 90% - - calculate blood flow
Poor image quality
Pharm
0.74 MeV, positron range 4.1 mm
Not for cardiac function
Combi with CTA
No contrast between myocardium and blood pool (no retention)
CFR threshold 2.5 - - >50% lumen narrowing + flow reserve <0.8
MPI interpretation
Reconstruction using iterative algorithm
Summed stress score, threshold 3
Summed rest score >3 and
Summed difference score >1 - - nonreversible scar
MRI
Gold standard for LVEF and wall motion
SPECT
Sensitivity 87%
Specificity 70%
For 50% stenosis
PET
Sensitivity 90%
Specificity 81%
Higher accuracy
Better for obese
Normal stress only
Homogenous perfusion
SSS <3
Normal LV cavity size, function, wall motion
Infective endocarditis
Involve leads
Shift from strep to staph
Septic emboli 30% - - splenomegaly, glomerulonephritis, peripheral stigmata
Heart murmur 85%
Roth spot = retinal hemorrhage with white center
Higher evidence - PVE
Echo first line
TC-HMPAO-WBC
FDG - - confirm/exclude in case of possible/rejected, assess embolic burden in case of definite
Prosthetic valve endocarditis
Image
Cardiac CT - - paravalvular lesion = major criterion
FDG or TC-HMPAO-WBC - - abnormal uptake = major criterion
Imaging of Recent embolic events or infectious aneurysm = minor criterion
Cardiovascular Implantable Electronic device CIED
Site - - generator’s pocket vs intravascular leads or epicardial leads
Origin of infection - - pocket erosion, localized infection of generator’s pocket, bacteria from a remote site
Staph aureus or coagulase-negative staph
CIED image
Early infection - - within few months after implantation - - acute/subacute infection of pulse-generator pocket, bacteremia, fever
Late infection - - several years
Most often - transvenous or epicardial leads - - complication pericarditis, myocarditis, right sided endocarditis
Implantable LV Assist device LVAD
Mediastinum drivelines and device surface
Big five: Staph aureus, enterobact, pseudomonas aeruginosa, coagulase-negative staph, corynebact
CT - - edema as primary sign of infection
Vascular prosthetic infection
Inguinal region 13% > aorto-bifemoral bypass > femoropopliteal bypass
Late - - 4-6 months - - no septicemia, no graft incorporation with surrounding tissue + perigraft fluid
Staph aureus, E coli, Staph epidermidis
Bentall procedure
Correction of aorta defects by composite aortic graft or vascular tube graft with mechanical or biologic valve
Infection 3%
Staph aureus 35%
MRSA 20%
Vascular prosthetic infection
Image
TC-HMPAO-WBC - - graft involvement even in first month after surgery and low grade infection
FDG - - focal uptake around prosthesis
Myocarditis
Enterovirus
Troponin 1 elevated
FDG - - diffuse uptake
Chronic active EBV - - myocarditis vs hypertrophy due to elevated pulmonary artery pressure (RV uptake)
TB - - heterogenous uptake
Viral - - no manifest with perfusion defect
Acute pericarditis
FDG - - mild/moderate uptake vs neoplasm (focal soft tissue mass)
Meningococcal sepsis and AIDS - - intense pericardial uptake - - pericarditis
TB - - mediastinal supraclavicular LN
Pericarditis as manifestation of GCA - - idiopathic pericarditis + uptake in pericardial space + hypermetabolism of thoracic and abdominal aortic wall
Cardiac Sarcoidosis
Biopsy - - 20% sensitivity
FDG - - patchy uptake, low specificity
Combi with MPI - - dd scar tissue vs normal myocardium
Most often ventricular septum
SUV max cutoff 4.0
Rb82 - - concominant abnormality
GA-citrate - - sensitivity 36%
Cardiac Amyloidosis
Genetic - - ATTR
Non genetic - - Al - - light chain amyloid
DD hypertrophic and restrictive cardiomyopathy
Echo, MRI - - No dd ATTR vs AL
AL - - cardiac uptake <50%,no muscular, but visceral uptake
Intensity of DPD - - predictor of major adverse cardiac outcomes - - negative correlation with LV function
DPD or PYP 740 MBq - - WBS 1h and 3h
F-fluoride PET/MR- - greater spatial resolution
Viable myocardium FDG and MIBG
EF <35% + viable myocardium (FDG) - - revascularisation
Glucose load PO 25-100g or IV - - insulin response - - overexpression of GLUT4 - - switch metabolism to glucose over fatty acids
Insulin administration - - image 2-3h after
MIBG IV 185 MBq over 1-2 min - - 10 min anterior thorax 128*128 - - 30 min and 3-4h - - heart/mediastinum ratio - - threshold 1.6
Large vessel vasculitis
Giant cell arteriitis GCA - - extracranial involvement 30-74%
Temporal artery biopsy - - 15-40% false negative
FDG - - no standard definition of vascular inflammation
Vessel/liver ratio
Arterial SUV max
CZT SPECT
Better resolution and image quality
Less acquisition time
Less radiation exposure
Oral glucose load protocol
25-100g PO
Check sugar before and after 60 min
Sugar 100-140 - - FDG
Sugar >140 - - 2 IU insulin - - FDG
TC-HMPAO-WBC
WBS, spot thorax at 30 min, 4-6h and 20-24h after reinfusion
At least 1 focus of abnormal uptake + increase with time - - positive
Hot spot in lung, cold spot in spleen or spine - - embolism
PVE - - mild activity on first exam - - disappear on second - - favourable outcome
FDG
Infective endocarditis
Heparin - - 5 fold increase in blood free fatty acids
Complications of IE - - mycotic aneurysm - - WBS
IE delayed image - - false positive
Increased uptake in posterior part of heart - - fat containing mass at interarterial septum
After valve implantation - - 3 months
Early detection of embolic events
MUGA = gated blood pool
Trastuzumab = Herceptin - - Cardiotoxic
Arthracyclines - - Cardiotoxic
Radio and chemo - - pericardial effusion
Before and after chemo - EF measurement
Gold standard for LVEF
Erythrocyte labeling
Binding to beta chain of Hb by stannous chloride
Anterior and LAO (best septal)
Data from 300-500 cardiac cycles
Stop manual, predefined on time or counts or number of cycles
Fourier analysis
Independent from mathematic assumption unlike Echo
LVEF impaired - - no Cardiotoxic agent
>10% decrease in LVEF - - <50% - - stop
MPI indication
Detection of coronary heart disease
Functional significance of coronary stenosis
Prognostic stratification
Monitoring effects of treatment
Assessment of myocardial viability
Adenosine receptors
A1 - - AV block
A2a - - coronary arteriolar vasodilation
A2B - - peripheral vasodilation, bronchospasm
A3 - - bronchospasm
LBBB
Regadenoson
Inferior wall
Right coronary artery
Best view for LVEF
LAO 45°
Postop inflammation
Infective endocarditis
Thoracic aorta prosthesis after Bentall procedure
ACS unstable
Abs Contra for
Exercise
Vasodilator
Debutamine
Acute PE
Abs Contra for
Exercise
Severe pulmonary hypertension
BP >200/110
Abs Contra for
Exercise
Vasodilator (uncontrolled BP)
Dobutamine (uncontrolled BP)
Acute aortic dissection
Abs Contra for
Exercise
Dobutamine
Symptomatic severe aortic stenosis
Abs Contra for
Exercise
Vasodilator
Hypertrophic obstructive cardiomyopathy
Abs Contra for
Exercise
Vasodilator
Symptomatic Arrhythmia
Abs Contra for
Exercise
Dobutamine (atrial tachyarrhythmia with uncontrolled ventricular response + prior history of VT)
Acute myo, peri and endocarditis
Abs Contra for
Exercise
Decompensated CHF
Relative Contra for
Exercise
Active DVT
Relative Contra for
Exercise
LBBB, pacemaker
Relative Contra for
Exercise
Dobutamine
Hypertension + rest BP >200 /110
Relative Contra for
Exercise
Recent stroke or TIA
Relative Contra for
Exercise
Aortic stenosis
Relative Contra for
Exercise (moderate or severe)
Vasodilator (severe)
Dobutamine (severe)
History of severe bronchospasm
Abs Contra for
Vasodilator
Greater than I AV block or sick sinus syndrome
Abs Contra for
Vasodilator
Systolic BP <90
Abs Contra for
Vasodilator
Cerebral ischemia
Abs Contra for
Vasodilator
Mild to moderate asthma and COPD
Relative Contra for
Adenosine
Dipyridamole
Severe sinus bradycardia <40
Relative Contra for
Vasodilator
Mobitz 1 AV block II Wenckebach
Relative Contra for
Adenosine
Regadenoson
Severe atherosclerosis of extracranial artery
Relative Contra for
Vasodilator
Use of dipirydamole 24 h
Relative Contra for
Vasodilator
Beta blockers
Relative Contra for
Dobutamine
Symptomatic or large aortic aneurysm
Relative Contra for
Dobutamine
ST depression
Early termination for
Exercise (>3 mm)
Vasodilator and Dobutamine (>2mm + chest pain)
ST elevation >1mm without Q
Early termination for
Exercise
VT, SVT or AFib with high heart rate
Early termination for
Exercise
Vasodilator (persistent AV block II or III or sinoatrial block)
Dobutamine (significant cardiac Arrhythmia)
Decrease in systolic BP >20 despite increasing workload
Early termination for
Exercise
Vasodilator (<80)
Systolic BP >250 or diastolic BP >130
Early termination for
Exercise
Dobutamine (230/115)
Angina cause distress
Early termination for
Exercise
CNS symptoms
Early termination for
Exercise
Peripheral hypoperfusion
Cyanosis, pallor
Early termination for
Exercise
Vasodilator
Dobutamine
End systole
Frame with lowest number of counts in ROI around left ventricle
False positive anterior and septal wall defect
Breast attenuation
