Pulm: Diagnostic Imaging Flashcards
What is the initial test that should be ordered to evaluate respiratory sxs?
CXR
What 3 views should be obtained with CXR?
PA, AP, lateral decubitus
What is the A,B,C,D,E,F approach to reading a CXR?
Airway Bones Cardiac Shilouette Diaphragms Edges Fields
Biggest benefit of CXR over other imaging modalities?
Low radiation exposure
You see a CXR showing no vasculature on the left side. What is lack of vasculature concerning for?
PTX
CXR shows hampton’s hump. What is this concerning for?
Pulmonary infarct/PE
Two major limitations for CXR?
radiation exposure (cumulative)
Some conditions cannot be detected
Can CXR be done in pregnancy?
no
Which imaging modality should be ordered?
Clarify CXR Characterize pulm. nodules Assist in dx detect/stage neoplasm evaluate mediastinal mass
CT
What type of CT?
Fast
Continuous
Takes < 5 min
Spiral
What type of CT?
1mm slices
better detail
used for fibrosis/emphysema
High resolution
What type of CT?
Less detail
Used for screening
Low-dose
What type of CT
10mm slices
Step & shoot style
25-30min
Conventional
What are 4 types of mediastinal mass? (4 Ts)
teratoma
thymoma
thyroid CA
Terrible lymphoma
Can CT be performed with implanted devices?
yes
Radiation exposure from CT is ___ which is ___ x a CXR
8 mSv, 80x
Can you do CT with pregnancy?
no
CTPA is ___ x the radiation dose of a single CXR
150x
What must you ask women prior to all imaging?
LMP
Are kids more or less radiosensitive than adults?
more
What type of contrast is often used with CT?
Iodine
When is contrast CT indicated?
Visualize Vessels and Malignancy
Trauma
What are three risks of CT with radiocontrast?
allergic rxn
contrast induced nephropathy
lactic acidosis if taking metformin
How do you avoid allergic rxn to contrast?
pre-treat with prednisone and benadryl
What is the typical onset of allergic rxn to contrast?
5-60 min
24-48 hours after contrast administration, a patient presents with:
Creatinine 0.5 + (25% from baseline)
What condition should be suspected, when do sxs peak
radiocontrast induced nephropathy
peak 3-5 days
Caution should be taken in administering radiocontrast if creatinine or GFR values are…
Creat: > 1.5
GFR < 60
What 5 populations need to have renal fxn tested prior to radiocontrast?
age > 60
hx renal disease
hx HTN treated wih meds
hx of DM
metformin use
This imaging modality assesses pulmonary vasculature.
It can be performed with:
CTPA
Direct pulm. angiography
pulm MRI
Pulmonary angiography
What test has largely replaced conventional, catheter-directed pulmonary angiography?
CTPA
This imaging modality is useful for detecting:
PE
Aortic Dissection
SVC Syndrome
CTPA
What is the radiation exposure for CTPA?
10-15 mSv
What might be missed with CTPA imaging?
sub-segmental PE
What is the gold standard imaging modality to evaluate PE?
catheter-directed pulmonary angiography
direct pulm. angiography
A patient has an inconclusive V/Q scan and CTPA, but you still suspect PE. What should you order?
direct pulmonary angiography
What are 5 risks of direct pulmonary angiography?
- bleeding/hematoma
- arrhythmia
- allergic rxn
- CIN
- radiation
Which imaging modality:
has limited usefulness for pulmonary disease
Less detailed view of parenchyma
No ionizing radiation, bone artifacts
MRI
What imaging modality is useful for visualizing the hilum, mediastinum, cancers, and lacks iodine contrast?
MRI
What are three big limitations to MRI?
pt. must remains still
claustrophobia
body habitus limitations
What are the contraindications for MRI (4)?
implanted pacemaker/defib
metal in eye
aneurysm clip
Cochlear implant
This imaging modality:
Useful in evaluation of PE and pre-op assessment for lung resection
V/Q Scan
What are the two phases of the V/Q Scan and what is used for visualization?
IV phase: technitium 99 bound to albumin
Inhalation phase: radio-labeled xenon gas
A V/Q mismatch indicates…
imbalance of blood flow and ventilation
What is a major limitation of V/Q scan?
sensitive for PE, but poor specificity (few false- neg, high false-positive)
If you have a normal CXR but high suspicion for PE, what can be used in pregnant patients or those who can’t tolerate CTPA/direct angiography?
V/Q Scan
What is the test of choice for PE dx in pregnant women?
V/Q Scan
What are 2 major benefits to the V/Q Scan?
- rare allergic reaction
2. low dose radiation
For what condition is PET scan used?
detection of CA
What is superior for mediastinal imaging, CT, MRI, PET>
PET
What is used for contrast in PET scan?
FGD–radioactively labeled glucose
Where does FGD accumulate?
cells with high metabolic activity: CA cells, heart, kidneys, bladder
This imaging modality has the following benefits:
- detects biochem changes before appearance on CT/MRI
- Short-lived radioactivity
- combined with CT/MRI to give full picture of anatomy and metabolism
PET
The following imaging modality has the following limitations:
- 140 x CxR radiation
- False results occur with metabolic imbalance
- time sensative
- High cost
PET
This imaging modality has the following indications:
- Bedside detection of pleural effusion, HTX, PTX
- Guidance for thoracentesis
- guidance for thoracostomy tube placement
Thoracic ultrasound
The seashore sign on thoracic ultrasound indicates…
normal lung
The barcode sign on thoracic ultrasound indicates:
PTX/no chest wall motion
What imaging modality has the following diagnostic indications?
- evaluation of pneumonia, hemoptysis, cough
- dx of transesophageal fistula/tracheobronchomalacia
- tissue sampling
Bronchoscopy
What are the 2 therapeutic indications for bronchoscopy?
Removal of excess mucous or FBs
ET tube placement
When should a rigid bronchoscope be used?
foreign body removal
What are the risks of bronchoscopy? (5)
Bleeding Infx Bronchospasm Perf. PTX
What are the contraindications for bronchoscopy? (5)
Severe Hypoxia Risk of bleeding Pulm. HTN Severe cough Tracheal stenosis
