L9: Pulmonary Diagnostic Imaging Flashcards
List 5 indications for ordering chest x-ray.
- SOB
- Persistent cough
- Hemoptysis
- Chest pain or injury
- Fever
Describe the systematic approach to reading a CXR.
A: Airways (trachea midline?) B: Bones (good inspiration, fractures?) C: Cardiac silhouette/CPA (are they clear?) D: Diaphragms (is there free air?) E: Edges (pleural plaques, effusion?) F: Fields (infiltrates, nodules?)
What are the 2 most basic views that should be ordered for a CXR?
PA and Lateral
What benefits does a lateral view have?
Pts lay on L side
Helps to not significantly magnify the heart
Allows us to see posterior structures
When would an apical lordotic view be useful?
When trying to visualize the apices of the lungs (such as with TB)
*Pt positioned at 30 degrees forward
A Hampton’s Hump seen on CXR is indicative of a:
Pulmonary infarct
What conditions cannot be seen on a CXR?
Very small cancers
Pulmonary emboli
List 5 indications for ordering a CT scan of the lungs.
- To clarify ABNORMAL CXR
- Characterize PULMONARY NODULES
- Assist in DIAGNOSIS of clinical signs/sxs (cough, SOB, CP, fever)
- DETECTION and STAGING of 1*/metastatic lung neoplasms (including SCREENING for lung CA)
- Evaluate suspected MEDIASTINAL or HILAR MASSES
1mm slice, better detail
This type of CT scan is a:
High resolution (HRCT)
10mm slice, “step and shoot”, takes 25-30 minutes
This type of CT scan is a:
Conventional scan
Less detail, used for screening
This type of CT scan is a:
Low dose (LDCT)
Faster, continuous, takes <5 minutes
This type of CT scan is a;
Helical (spiral) CT
What type of CT scan helps to visualize blood vessels?
CT angiography
What 2 populations should we avoid giving CT scans to if possible? Why?
Peds: more radiosensitive, increased risk for leukemia and brain tumors with CT scans
Pregnant women: In utero exposure linked to pediatric CA mortality; ALWAYS ASK LMP PRIOR TO IMAGING!
What type of radiocontrast is used with CT? What are 3 scenarios we would use contrast for?
Iodine
Visualization of:
- Vessels
- Malignancies
- Chest trauma
What are the potential risks to consider when giving a patient radiocontrast for a CT?
- Allergic reaction (minor to severe)
- Contrast induced nephropathy (CIN)
- Development of lactic acidosis if taking glucophage (Metformin) - may require holding for 48 hrs after imaging
What are the risk factors for a pt developing an allergic contrast after receiving radiocontrast? How can you treat this prophylactically?
Risk factors: Prior rxn, hx of asthma or atopy (NOT SHELLFISH!)
Pre-treat with prednisone and diphenhydramine (Benadryl)
What are the lab values seen in a patient with radiocontrast induced nephropathy? When do sxs start presenting and when do they peak?
Increase in serum Cr >/= 0.5 mg/dL or >/= 25% from baseline
- sxs appear 24-48 hrs post exposure
- Peaks at 3-5 days
A pt with decreased kidney function should not be given radiocontrast if their:
Creatinine > 1.5 mg/dL or GFR <60
You should assess renal function prior to giving contrast if a patient presents with any 5 of the following indications:
Age > 60 yrs Hx of renal disease Hx of HTN treated with medication Hx of diabetes Taking Metformin
What has largely replaced conventional (catheter directed) pulmonary angiography?
CT Pulmonary Angiography (CTPA)
*Less invasive, less expensive, less time-consuming
What are 4 things a CTPA is useful in detecting?
- PE
- Aortic dissection
- Superior vena cava syndrome
- Identifying vascular malformations and arterial invasion by a neoplasm
What are 5 risks and limitations of a CTPA?
- May miss sub-segmental PE
- Allergy risk to contrast
- CIN from contrast
- Radiation exposure
- Body habitus >450lbs
What is the gold standard for an evaluation of a PE?
Catheter-Directed Pulmonary Angiography (“Direct PA”)
- Needle/catheter inserted into R femoral or internal jugular vein; into R side heart and pulm. arteries
- Dye injected, x-rays taken
