Exam 2: Pulmonary Diagnostic Imaging Flashcards
What pulmonary diagnostic tests do not have any radiation?
US, MRI, and bronchoscopy
What is the initial study to evaluate respiratory problems?
CXR
What are the indications for CXR?
SOB, persistent cough, hemoptysis, chest pain, and fever
What is an AP vs PA CXR view?
PA: beam coming from behind
AP: beam coming from front
What is the systematic approach to reading a CXR
A: Airway B: Bones C: Cardiac silhouette D: Diaphragms E:Edges F: Fields
What is the apical lordotic view used for?
Potential TB
What is Hampton’s hump?
A wedge shaped opacity seen on XR relegated to pulmonary infarct
What is the radiation exposure of a CXR?
0.1 mSv
What are the 5 different kinds of CT?
Conventional scan, helical CT, High resolution, low dose, and CT angiography
What are the indications for a CT?
- To clarify an abnormal CXR
- Characterize pulmonary nodules
- assist in diagnosis of clinical signs/symptoms
- detection and staging of primary/metastatic lung neoplasms
- evaluate suspected mediastinal or hilar masses
What is the radiation exposure of a CT?
~8mSv
What two populations should you use caution when ordering a CT?
- Pediatrics (increased risk of brain tumor, leukemia, and radiation risk is compounded by longer lifespan)
- Pregnant women (in utero exposure linked to pediatric CA mortality, ALWAYS ASK LMP PRIOR TO IMAGING)
What kind of contrast is used with CT?
Iodine contrast
What is the purpose of contrast?
To enhance differences in densities of various structures
When should you use contrast?
When evaluating vessels, malignancy, and trauma
What are the risks associated with radiocontrast?
- Allergic reaction
- Contrast induced nephropathy
- Lactic acidosis if taking Metformin
What are the symptoms of a contrast allergic reaction?
Flushing, pruritis, urticaria, angioedema, wheezing, anaphylaxis
What are the risk factors for a contrast allergy?
A prior reaction, hx of asthma or atopy
**Shellfish allergy is NOT a contraindication!
How should you pretreat a patient with a contrast allergy that you need a contrast CT for?
Pretreat with prednisone and Benadryl
What is radiocontrast induced nephropathy?
An increase in serum creatinine >0.5 or >25% from baseline
What are the creatinine and GFR levels in which you should not order a contrast CT?
If creatinine >1.5 or GFR < 60
When should you check renal function prior to radiocontrast?
older than 60, history of renal disease, diabetes, HTN treated with medication, or taking metformin
What modalities is pulmonary angiography used in conjunction with?
CTPA, direct pulmonary angiography, and pulmonary MRA
What is used in detection of PE, aortic dissection, and SVC syndrome?
CTPA
What is the radiation exposure from CTPA?
10-15 mSv
What is the gold standard in evaluation of PE?
Catheter-directed pulmonary angiography
When is catheter directed pulmonary angiography useful?
If V/Q scan or CTPA is inconclusive high there is high clinical suspicion of PE
What are the risks associated with catheter-directed pulmonary angiography?
Bleeding or hematoma at insertion site, heart arrhythmia, allergic reaction, potential nephrotoxicity, and radiation exposure of 5mSv
What kind of contrast is used in MRI?
Gadolinium
What are V/Q scans used for?
Evaluation of pulmonary embolisms and for pre-op assessment prior to lung resection
What makes the IV (perfusion) phase of a V/Q scan present?
Technetium 99 labeled to albumin
What makes the inhalation (ventilation)phase present in a V/Q scan?
Radio-labeled xenon gas
What is the test of choice for diagnosis of PE in pregnant women?
V/Q scan
What are PET scans used for?
Mostly cancer, superior to CT for mediastinal imaging because it can identify tumors in normal sized lymph nodes
How does a PET scan work?
Fluorodeoxyglucose (FGD) is a radioactive glucose that is injected into patient and it accumulates in tissues/organs with high metabolic activity and cancer cells have very high metabolic activity
-Patient is scanned and measurements of the uptake are made in SUVs
What SUV value from a PET scan raises possibility of malignancy?
SUV > 2.5
When can a false negative occur in a PET scan? False positive?
False negative: slow growing tumors
False positive: can occur with inflammatory lesions/granulomas
What are the indications for thoracic US?
- Bedside detection of pleural fluid, hemothorax, or pnuemothorax
- Guidance of thoracentesis
- guidance for placement of thoracostomy tubes
What are the therapeutic uses of bronchoscopy?
Removal of excess mucous or FB, and ET tube placement
