Transcript Slide 1

Chest Imaging On Call
Mia Skarpathiotakis, PGY-4
July 13, 2009
Special Thanks
• Jonathan Mandel
How to survive call:
Classic Chest Call Cases
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PE
Spontaneous Aortic Injury
Traumatic Aortic Injury
Miscellaneous
Hi, I need a STAT high resolution CT to rule
out a pulmonary embolism.
Risk Factors for PE
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Immobilization >72 hours
Recent hip surgery
Cardiac disease
Malignancy
Estrogen use (prostate cancer, contraceptives)
Prior DVT
***Bonus: remember Virchow’s Triad for thrombogenesis?
– Alterations in blood flow (ie. stasis): bed rest, inactivity, CHF
– Injury to endothelium: trauma, surgery
– Thrombophilia
Signs & Symptoms
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Chest pain, 90%
Tachypnea, 90%
Dyspnea, 85%
Rales, 60%
Cough, 55%
Tachycardia, 40%
Hemoptysis, 30%
Fever, 45%
Diaphoresis, 25%
Cardiac gallop, 30%
Syncope, 15%
Phlebitis, 35%
Options before doing the study
• Get D-Dimers
• If negative, rules out venous clot
• Only some hospitals have the sufficiently sensitive
ELISA test
• Often positive in elderly, inpatients, those with
virtually any comorbidity
• Get Leg Dopplers
• If negative, doesn’t rule out PE
Options before doing the study
• Ask if scan could be delayed to morning
• Was once the standard of care
• They will usually treat with heparin, and bring the
patient back
• If you’re swamped, tell them
• Never outright refuse the study – refer them to your
staff if you really can’t do the study, and they’re
giving you a hard time
Conditionally agreeing
• Get the patient’s creatinine
• Compute the creatinine clearance/GFR
CrCl 
(140  age )  weight  1.2
creatinine
Multiply by 0.85 if Female
Conditionally agreeing
• UHN Cutoffs:
• Normal patient: Clearance > 30
• Diabetic: Clearance > 50
• Diabetic on Metformin: Clearance > 60
• If they fail, higher risk for contrast nephropathy. You and
the clinician have to decide the merit of the scan now
given the risk
• Options include hydrating the patient overnight,
mucomyst 600mg PO BID for 12h before and 24h after
the scan, +/- HCO3
• Alternative: Do a V/Q Scan. Requirements: relatively
normal CXR, co-operative patient
Doing the Scan
• Call the tech: just say PE protocol
• (this is not HI-RES – it’s helical with thin cut reconstruction,
scanning at the pulmonary arterial phase)
CT Adequacy
• Main PE should be approx > 250
• Segmental/subsegmental should be > 200
to rule out PE at this level
CT Findings
• Intraluminal filling defect surrounded by
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contrast
Expanded unopacified vessel
Eccentric filling defect
Peripheral wedge-shaped consolidation
Pleural effusion
Some sites (SB) image lower extremities
Case 1
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Rule out PE
• Assess the contrast density in the pulmonary
arteries
• If not dense enough, repeat the scan vs. report sub-optimal
• Window correctly
• Look at all segmental branches
• Time consuming
Case 2
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Case 3
Hi, I have a patient with tearing back pain,
and different arm BPs.
Spontaneous Aortic Injury
• Should not delay
• No good way to rule out on CXR or
clinically
• Check creatinine clearance
• Often though, patient is sick enough that they’ll
want the study regardless
Spontaneous Aortic Injury
• Call the tech:
– Say “aortic dissection”
– This includes:
• Unenhanced chest
• Enhanced chest, abdo, pelvis
Case 1
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Case 2
Case 3
Spontaneous Aortic Injury
• 3 Types of Spontaneous Aortic Injury:
• Aortic Dissection
• Intramural Hematoma
• Penetrating Ulcer
• For the first two types, the key point is:
Does the lesion involve the aorta proximal
to the origin of the left subclavian artery. If
so, then SURGERY.
Spontaneous Aortic Injury
• Aortic dissection:
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Intimal flap – true and false lumen
Aortic root, proximal involvement, arch vessels
Rupture – high-density pleural or pericardial effusion
Abdominal ischemia – bowel, kidneys
• Intramural hematoma
• Only good on non-contrast scan
• Crescent of high-density in aortic wall
• proximal involvement – treat as type A dissection, i.e.
SURGERY
Aortic Trauma
“Borrowed” from a presentation by Marc Ossip and Caitlin McGregor,
graduated residents who are now staff at William-Osler and Sunnybrook
TRAUMA ARCH - PLANE FILM
• wide superior
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mediastinum (>8 cm)
depression of the left
mainstem bronchus
obliteration of the aortic
knob
deviation of NG to the
right of SP of T5
fracture first and second
ribs, sternum, scapula
• left apical cap
• AP window obliteration
• anterior displacement of
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trachea on lateral
fracture/dislocation of Tspine
widening of paravertebral
stripe
wide right paratracheal
stripe ( >5mm)
obscuration of azygous
arch
TRAUMA ARCH-CT
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mediastinal blood
aortic contour irregularity
flaps
extravasation
other injury
Case 1
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Case 2
CASE 2
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Miscellaneous Cases
Case 1
Case 1 - Pneumonia
Case 2
1 day
Case 2 – Pulmonary Edema
Case 3
Case 3 – Pericardial Effusion
Case 4
Case 4 – Ruptured Esophagus
More Practice Cases