Download Imaging Pulmonary Embolism

Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
May 2001
Imaging Pulmonary
Embolism
New ways to look at a
diagnostic dilemma
Emily Willner, HMS III
Gillian Lieberman, MD
Core Radiology Clerkship, BIDMC
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
New approaches to imaging PE:
Agenda
1.
2.
3.
Review two patients who had new
diagnostic modalities used for diagnosing
and/or treating PE
Review anatomy, differential diagnosis
and menu of tests available for PE
imaging.
Discuss algorithmic approach to use of
imaging modalities, and the strengths and
limitations of available tests.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Patient J.R.: A classic story
„ 64 year old man with recent diagnosis of
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metastatic pancreatic CA. Known mets to the
liver.
Presents to the ED with acute onset of sharp, Lsided pleuritic chest pain. Mild SOB for a few
days.
No cough or hemoptysis. No fevers or chills. No
leg symptoms
PMHx: Pancreatic CA. C4-5 ruptured disc.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
J.R.: Physical Exam
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Vitals: Afebrile, HR 72, BP 121/64, RR18, Sat
98% RA
Thin man, mildly uncomfortable.
Chest clear.
Heart RRR, II/VI SEM, no rubs or gallops.
Mild abdominal tenderness, + hepatomegaly
Normal lower extremity exam
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
J.R.: Chest X-ray
Images from BIDMC PACS
Poor inspiratory effort, but otherwise clear lungs. No pneumothorax, no effusions.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
J.R.: Ventilation/Perfusion Scan
Ventilation
•Essentially
normal
RAO
LPO
Ant
Post
LAO
RPO
L Lat
R Lat
Perfusion
• Shows possible
defect in LLL
RAO
LPO
Ant
Post
LAO
RPO
L Lat
R Lat
Image from BIDMC PACS
6
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
J.R.: Chest CT Angiogram w/
contrast showing embolus
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Image from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Embolus easier to visualize
scrolling through CT cuts
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Image from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Patient R.S.: An emergency on call
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58 y.o. man s/p cholecystectomy 2 weeks ago, rehospitalized for mental status changes
Abdominal/pelvic CT the day of admission
incidentally showed L femoral and ileac DVT;
heparin was started
The following day, he became acutely SOB, O2
sat 88%, tachy to 146, EKG: S1, Q3, T3.
Bedside echo: severe RV enlargement and
hypokinesis
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
R.S.: CT on admission revealed
DVT in left iliac v.
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Image from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
R.S.: Chest X-ray while SOB
Image from BIDMC PACS
AP upright film: Bilateral lower lung atelectasis. Otherwise clear lungs.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
R.S.: Large saddle embolus in L
and R pulmonary arteries
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Image from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
R.S.: Saddle embolus in R PA
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Image from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
R.S.: Angiography and suction
thrombectomy
Pre-thrombectomy
Large filling defect. Virtually
no flow to L lung.
Post-thrombectomy
After suction thrombectomy, flow
restored to L upper lung.
Images from BIDMC PACS
14
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Differential Diagnosis of chest
pain with SOB
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Respiratory: PE,
pneumonia,
pneumothorax,
pulmonary edema,
asthma/COPD,
bronchitis, lung CA
Cardiac: Pericarditis,
angina, MI, aortic
dissection
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GI: GERD,
esophageal spasm,
cholecystitis
Musculoskeletal:
Muscle spasm, pulled
muscle, rib fracture,
costochondritis
Psychiatric: Anxiety
15
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Classic presentation of PE
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Risk factors
ƒ Immobilization, surgery within 3 mo., trauma,
malignancy, CHF, MI, h/o VTE, postpartum or
hormone use
Symptoms
ƒ Pleuritic chest pain, dyspnea, cough, hemoptysis,
syncope
Signs
ƒ Tachypnea, rales, tachycardia, S4, loud P2, fever
<102 F
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Lung Anatomy
Arteries run with Bronchi
Image from info.med.yale.edu/caim/ct/contents.html
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Pulmonary vasculature and bronchi
Bronchus
Pulmonary
trunk
Pulmonary arterial
anatomy
Pulmonary trunk
Æ 2 Main pulmonary
arteries
Æ Lobar arteries
Æ Segmental arteries
ÆSubsegmental arteries
Image from Digital Anatomist, http://www9.biostr.washington.edu/da.html
18
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
CT correlation and crosssectional anatomy T5-6
Aorta
Pulmonary artery
bifurcation
Mainstem
bronchus
Pulmonary artery
bifurcation
Aorta
Mainstem
bronchus
Pulmonary artery
bifurcation
Aorta
Image from Digital Anatomist,
http://www9.biostr.washington.edu/da.html
Mainstem
bronchus
19
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Imaging tests in suspected PE
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Plain chest film: First
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test; r/o other etiology
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Ventilation/perfusion
scanning
Pulmonary
angiography: the “Gold
Standard” test
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Helical CT scan/ CT
angiography
MR imaging/
angiography
Other: LE Venous
duplex Doppler US,
echocardiography
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Chest X-ray findings in PE
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Most films (86%) are
abnormal. Common
findings are:
atelectasis
parenchymal opacity
pleural effusion
cardiomegaly
hemidiaphragm elevation
central pulmonary artery
prominence
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Few show “classic PE”
findings:
Westermark’s sign = loss of
pulmonary vasculature distal to
central embolus.
Hampton’s hump= wedgeshaped, pleural based opacity
representing infarct
Fleischner's sign = regional
oligemia in the presence of an
ipsilateral enlarged pulmonary
artery
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Westermark sign
Image from Virtual Hospital, www.vh.org
22
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Hampton’s Hump
From www.med.virgina.edu/medwww.med.virgina.edu/med-ed/rad
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Ventilation/perfusion scanning
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Nuclear medicine test, IV
injection of 99Tc labeled
to albumin maps perfusion
Inhalation of radioactive
tracer shows ventilation
Read as high,
intermediate, low
probability, or normal
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Normal perfusion r/o
embolus
High prob scan, 42%
have emboli; 96% if
correlated with high
clinical prob
Intermediate and low
prob scans =
indeterminate
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Normal V/Q scan
Ventilation
RAO
LPO
Ant
Post
LAO
RPO
L Lat
R Lat
Perfusion
RAO
LPO
Ant
Post
LAO
RPO
L Lat
R Lat
Image from BIDMC PACS
25
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
High Probability V/Q scan
Ventilation
•Few small
defects
RAO
LPO
Perfusion
• Multiple
RAO
Ant
Post
Ant
LAO
RPO
LAO
L Lat
R Lat
L Lat
unmatched
perfusion
defects
LPO
Post
RPO
R Lat
Image from BIDMC PACS
26
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Following up indeterminate V/Q
72% pts have indeterminate scan
„ Emboli detected in 30% of intermediate
scans and 14% of low prob scans
„ THUS, PIOPED recommends f/u with
PAgram in this group
„ Only 5% in this group have pulmonary
angiography!! Management is instead based
on clinical judgment.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Diagnosing PE using V/Q scans:
one algorithm
V/Q Scan
Normal perfusion
No treatment
Non-diagnostic
HIgh probability
Clinically stable
Cinically unstable
Eval bilateral
lower extrem.
Pulmonary angiography
Nondiagnostic/
negative
+ DVT
No PE
PE present
Serial leg studies v.
angio
TREAT
No treatment
TREAT
TREAT
Chart adapted from UpToDate, ATS guidelines 1999.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Pulmonary Angiography
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The “gold standard” test for PE
Trans-venous; mortality < 1%, morbidity 2-5%
Interobserver variability: PIOPED found a 92%
concordance in PE cases
Least sensitive for subsegmental emboli
Diagnostic test can be combined with intervention
(Greenfield (IVC) filter, thrombolysis,
thrombectomy)
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Normal Pulmonary Angiogram
To RUL
Left PA
To LUL
To RML
To LLL
To RLL
Right PA
Images from BIDMC PACS
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
CT angiography in PE diagnosis
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Helical CT with iodinated contrast bolus; 20-30
sec. scan, may be done in 2 breath-holds
Sensitivity: 86% for proximal vessels (main
through segmental a.); 53-100% overall.
Specificity: 93% for proximal vessels; 81-100%
overall.
CT has similar sensitivity to V/Q scanning, but a
negative CT is not as good as normal perfusion in
r/o PE
Should we re-think the algorithms? What is the
role for CTA?
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Diagnosing PE: an algorithm
using helical CT as the initial test
Supect PE
Low clinical
suspicion
Intermediate or
high clinical
suspicion
D-dimer
CT angiography
Normal
Abnormal
PE excluded
CT angiography
Other dx
PE
No PE
Consider lower
extremity evaluation
Chart adapted from Ryu et. al., 2001.
• Consider V/Q scan if contraindication to IV contrast.
• V/Q has good utility as first test when patient has no pathology
on CXR and no hx of cardiac or pulmonary disease
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Normal CTA
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Images from BIDMC PACS
Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Helical CT angio overview
Plus
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Very fast
Evolving technology
Æfaster scans and thinner
slices
May give alternate
diagnosis if negative for
PE
3-D reconstructions
Negative scanÆ safe to
withhold anticoagulation
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Minus
Iodinated contrast
(renal insufficiency)
Radiation exposure
Poor visualization of
clots in subsegmental
arteries and obliquely
oriented vessels
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
3-D CT reconstruction: R.S.
Image from BIDMC PACS
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
CT in diagnosis of DVT: One stop
shopping?
Recent data has suggested that CT of the
lower extremities may be done at the same
time as chest CTA to yield greater
diagnostic accuracy
„ One contrast bolus and one scan
„ In future, possibly replace venous US in
patient already undergoing CT ?
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Role of MRA in diagnosis of PE
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Plus
Excellent images
No iodinated contrast
Sensitivity and specificity
similar range to CTA
Real-time reconstructions/
flow images
Future:, ventilation
scanning
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Minus
Longer scan time
(minutes v. seconds)
Prolonged breathholding (30+ sec.)
Expensive
Poor sensitivity in
subsegmental a. clots
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Gadolinium contrast MRA
Normal
Image from www2.medical.philips.com/mri/Applications/
Cardiac/Angiography.asp
Cardiac/Angiography.asp
MRA of a large embolus
Image courtesy of Dr. Thomas Vrachliotis
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Summary: Advances in imaging
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CXR remains the initial test of choice.
V/Q scanning retains a role in healthier patients.
Helical CT is sensitive, specific, fast, and gives
alternate diagnoses. Potential for LE imaging. Needs
more investigation to fully delineate role.
Pulmonary angiography has a role especially in
patients who will need interventions.
MR is promising but currently scans too long and test
too expensive.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
References
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American Thoracic Society. The diagnostic approach to acute venous thromboembolism. ATS
guidelines. Am J Resp Critical Care Med 1999; 160: 1043.
Goodman LR, Lipchik RJ, Kuzo RS. Subsequent pulmonary embolism. Risk after negative helical
CT. Prospective comparison with scintigraphy. Radiology 2000; 215: 535.
Kline JA, Johns KL, Colucciello SA, Israel EG. New diagnostic tests for pulmonary embolism. Ann
Emerg Med 2000; 35(2): 343.
Maki DD, Warren BG, Abass A. Emerging technology in clinical medicine: Recent advances in
pulmonary imaging. Chest 1999; 116(5): 1388.
PIOPED investigators. Value of ventilation/perfusion scan in acute pulmonary embolism. JAMA
1990; 263: 2753.
Rathburn SW, Raskob GE, Whisett TL. Sensitivity and specificity of helical CT in the diagnosis of
pulmonary embolism: a systematic review. Ann Int Med 2000. 132(3): 227.
Ryu JH, Swensen SJ, Olson EJ, Pellikka PA. Diagnosis of pulmonary embolism with use of
computed tomography.
Thompson BT, Hales, CA. Clinical manifestations and diagnostic strategies for acute pulmonary
embolism. Up To Date 2001.
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Emily Willner,
Willner, HMS III
Gillian Lieberman, MD
Acknowledgements
Many thanks to Dr. Michelle Swire for her help with cases and images,
Dr. Lieberman for her ideas and suggestions, and to Dr. Thomas
Vrachliotis for his MR images.
Thanks to my Radiology classmates who made doing this presentation
much more fun.
Thanks to Beverlee Turner for all her technical help.
Special thanks to Larry Barbaras and Cara Lyn D’amour,
our WebMasters.
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