Nuclear - Diagnostic tests/Procedures/Protocols/Artifacts Flashcards
What is the most sensitive and specific tests for prediction of recovery of regional function after revascularization?
PET - Most sensistive
Echo - Most specific
MRI - varies by technique
What are indications for performing pharmacologic stress testing in lieu of a treadmill test for single photon emission computed tomography myocardial perfusion imaging (SPECT MPI)?
- Severe, symptomatic PAD
- Chronotropic incompetence
- LBBB
- Neurologic and muscular disorders
- Paced-rhythm
What is the problem with LBBB or paced rhythms and exercise nuclear stress testing?
- may develop a septal perfusion abnormality in the absence of septal branch or LAD disease
- due to decreased septal blood flow at rapid heart rates
***pharmacologic stress testing –> HR not increased –> specificity improves
What is an abnormality that may be seen with permanent pacing on SPECT MPI?
- asynchronous contraction of the myocardium
- Perfusion defects in the absence of disease:
- septum
- inferior wall
- apex
What are the agents of choice for pharmacologic stress testing in patients with LBBB and v-paced rhythms?
- Adenosine
- Dipyridamole
- Regadenoson
What is the mechanism of action of adenosine?
Why is this medication used?
- nonselective agonist that causes coronary vasodilation when it activates the A2A receptor
- Least amount of binding to the other receptors (A1, A2B, A3) which produce most of the side effects when activated
- chest pain
- bronchiolar constriction
- mast cell degranulation (flushing)
- negative chronotropic, inotropic, dromotropic effects
What are contraindications to pharmacologic stress testing with adenosine?
- Medications:
- caffeine and aminophylline
- comptetive adenosine receptor antagonist (binds without stimulating) –> prevent vasodilation –> lower sensitivity for detection of CAD
- dipyridamole
- induces vasodilation
- resting study will have a high baseline blood flow –> flow reserve during stress will be decreased
- if used in addition to adenosine or regadenoson –> half-lives are markedly prolonged due to inhibition
- caffeine and aminophylline
- Severe obstructive lung disease (with active wheezing)
- adenosine or dipyridamole –> could stimulate A2B/A3 receptors that produce bronchial constriction
- 2nd / 3rd degree AV block or SSS without a PPM
- A1 receptor activation (located in the SA, AV, atrial and ventricular myocytes) –> negative chronotropic, inotropic, dromotropic effects
How long should these agents be held prior to stress testing?
- Caffeine
- Aminophylline-containing compounds
- Dipyridamole
- Caffeine: 12-24 hours
- Aminophylline: 24-48 hours
- Dipyridamole: 24-48 hours
What is the prognostic value of ischemic EKG changes with normal perfusion images on:
- exercise stress testing
- vasodilator stress testing
- Exercise
- low risk of cadiac death or MI ( < 1% per year, if no DM)
-
Vasodilator
- Varies widely - some with normal coronaries and others with prognostically important CAD
- Angiography recommended to resolve prognostic uncertainty raised by these discordant findings
Describe the findings and next step
- 60 year old male with DM and exertional chest pain
- GXT:
- 3:30 minutes on Bruce protocol
- EKG: 2mm horizontal ST depression
- Symptoms: mild angina at peak

TID (transient ischemic dilation) + LHC
- high risk finding
- important finding if ischemic symptoms present

Describe the findings

MVCAD (multiple high-risk features)
- LAD perfusion defect
- marked TID
- Increased RV uptake of tracer at stress
- high risk finding

Describe the findings
- 64 yo male with prior MI presents with refractory pulmonary edema
- LVEF 28% with wall motion abnormalities
- LHC: chronic subtotal occlusion of large dominant CFx

Revascularization has a high probability of improving global and regional LV function
- Resting PET images (Rubidum-82 and F-18 FDG)
- Rubidium –> perfusion tracer
- FDG –> metabolism tracer
-
Hibernating myocardium
- Lateral wall demonstrates resting perfusion defect with robust metabolism (FDG)

Describe the findings:
- 56 year old female with hyperlipidemia and aypical chest pain

Anterior attenuation artifact (likely breast)
- Improvement in perfrusion from rest –> stress
- most likely attenuation artifact
- SPECT: anterior attenuation artifact, most likely breast
- Angiogram: normal

Describe the findings and next step:
- 54 year old female with intermittent chest pain x 24 hours
- EKG with nonspecific ST-T wave abnormaltiies
- Resting Tc-99m myocardial perfusion scan following injection (during chest pain) is obtained

- Findings: Large territory of inferior and lateral resting ischemia
- Next step: cardiac cath
- Angiography 90% lesion with ruptured plaque in large dominant LCX

Describe the findings and outcomes
- 63 year old male preesents with stable exertional chest pain x 1 year.
- Exercise Tc-99m myocardial perfusion scan:
- Exercise: 9:20 minutes on Bruce
- Symptoms: angina at peak stress c/w presenting symptoms
- ECG: 1.5mm horizontal ST depression at peak stress
- Recovery: ST depression/angina resolve 2 minutes into recovery

Aggressive medical therapy would be similar to PCI in this patient for reduction of cardiac death and myocardial infarction
- COURAGE trial - SIHD
- PCI relieves symptoms over the 1st year but doesn’t improve mortality or outcomes
- SPECT findings:
- inferior perfusion defect suggestive of one vessel CAD

Describe the anatomical orientation


Describe the findings:
- 37 year old male with palpitations and SOB x 3 years, slightly worse over the last few days
- Pharmacologic myocardial perfusion scan is performed

Diaphragmatic attenuation is present, with evidence for a chronic cardio-pulmonary process
- Increased RV uptake at stress and rest
- marked RV hypertrophy and massive RV dilation
- Dx: Ostium Secundum ASD
*** mild inferior wall ischemia

Describe the findings


Describe the findings


What do findings of RV uptake on nuclear mean?
LV becomes ischemic –> RV becomes a greater contributor to the LV
When is SPECT MPI appropriate following STEMI?
Stable patients prior to discharge who are not scheduled to undergo cardiac catheterization
- Class I - LOE B
- MPI (dipyridamole, adenosine, or regadenoson) prior or early after discharge to look for inducible ischemia is indicated since the results can further risk stratify the patient and help the clinician select the most appropriate treatment strategy
What are limitations to SPECT MPI in women?
What is an alternative test that can improve accuracy?
- Small LV chamber size
- Breast attenuation
- Obesity
- PET
- higher diagnostic accuracy
- addressess all problems
What is the problem with chamber size and SPECT MPI in women?
- women have smaller hearts than men –> diminishes accuracy
- adversely affects (especially if thallium-201 used)
- image quality
- diagnostic accuracy
What can be done to improve the diagnostic accuracy of SPECT MPI in women with breast attenuation artifact?
- breast attenuation artifact can be improved (70% –> 90%) with integration of
- rotating projection images
- wall motion
- attenuation correction











































