Post on 09-Apr-2017
بسم هللا الرحمن الرحيم
Dr AHMED ESAWY
An Article By
Dr. Ahmed Eisawy
MBBS M.Sc MD
Dr AHMED ESAWY
PULMONARY EMBOLISM
IMAGING
Dr AHMED ESAWY
• Pathology Of Pulmonary Embolism
• Imaging Of Pulmonary Embolism
• Pitfalls in Diagnosis of Pulmonary Embolism with Helical CT Angiography
• Nonthrombotic Pulmonary Embolism
• Other modalities
Dr AHMED ESAWY
Dr AHMED ESAWY
Dr AHMED ESAWY
Dr AHMED ESAWY
Dr AHMED ESAWY
• Multidetector spiral CT image shows anterior
segmental artery of the right upper lobe (arrow)
Dr AHMED ESAWY
• Multidetector spiral CT image shows the medial segmental artery of the right middle lobe (white arrow) and the right lower lobe artery (black arrow)
Dr AHMED ESAWY
• Multidetector spiral CT image shows left lower lobe
pulmonary artery (arrow)
Dr AHMED ESAWY
Cross-sectional antomy of central vessels . Dr AHMED ESAWY
Right Upper Lobe Segmental Vessels .
Right Lower Lobe Segmental Vessels . Dr AHMED ESAWY
Left Upper Lobe (Upper division) Segmental vessels Dr AHMED ESAWY
Left Upper Lobe (Lower division) Segmental vessels Dr AHMED ESAWY
Left Lower Lobe Segmental vessels Dr AHMED ESAWY
Pathology Of Pulmonary Embolism
Dr AHMED ESAWY
Pathogenesis of
pulmonary
thromboembolis
m
Dr AHMED ESAWY
Pathological findings of pulmonary thromboembolism are often considered in two categories: those in which the embolic episode
is acute and those in which the emboli are chronic are/or repeated (Weigs and Jaff,
2004).
Dr AHMED ESAWY
Pathological Findings in
Acute Pulmonary Thrombo
Embolism: Emboli were considered acute if they are partially or
completely occluded the arterial lumen and the arterial diameter was not reduced: In most instances
the lung parenchyma distal PE eighther normal or shows only mild atelectasis and minimal intraolvealar
hemorrhage or edema. (Müller et al., 2002).
Dr AHMED ESAWY
Chronic Pulmonary
Thrombo Embolism: Lung emboli were considered chronic if at least two of the
following features were present: 1-An eccentric location contiguous to the vessel wall. 2-Evidence of recanaliazation within the intraluminal filling
defect (circumferential filling defect with central or eccentric patent lumen).
3-Arterial stenosis or webs. 4-Reduction of more than 50% of the arterial diameter. 5-Complete occlusion at the level of stenosed arteries. (Müller et al., 2002).
Dr AHMED ESAWY
Pulmonary Embolism
thrombotic
non-thrombotic
Dr AHMED ESAWY
Imaging For PE Includes
- Chest radiography.
- Ventilation-perfusion (V/Q) lung scintigraphy.
- Pulmonary angiography.
- Computed tomography (CT, spiral or MDCT
- Magnetic resonance imaging (MRI).
-Echocardiography and transthoracic ultrasound.
- Imaging studies to search for thrombosis (DVT).
Dr AHMED ESAWY
Embolism without Infarction
• Most PEs (90%)
• Frequently normal chest x-ray
• Pleural effusion
• Westermark’s sign
• “Knuckle” sign abrupt tapering of an occluded vessel
distally
• Elevated hemidiaphragm
Dr AHMED ESAWY
Embolism with Infarction
• Consolidation
• Cavitation
• Pleural effusion
(bloody in 65%)
• No air bronchograms
• “Melting” sign of
healing (Heals with
linear scar)
Dr AHMED ESAWY
ray-Chest XPlain film radiography
• Initial CxR always
NORMAL.
Dr AHMED ESAWY
CXR
• Hampton’s Hump
– consists of a
pleura based
shallow wedge-
shaped
consolidation in
the lung periphery
with the base
against the
pleural surface.
Dr AHMED ESAWY
Watermarks sign. Chest radiograph demonstrates pulmonary oligemia in
the right mid-lung secondary to central right pulmonary embolus
Chest radiograph showing calcified pulmonary embolism
Dr AHMED ESAWY
Radiographic Eponyms Hampton’s Hump, Westermark’s Sign
Westermark’s
Sign
Hampton’s Hump
Dr AHMED ESAWY
Chest radiograph showing pulmonary infarct in right lower lobe
Dr AHMED ESAWY
V/Q
Scanning
Dr AHMED ESAWY
VQ Scan results 2
Perfusion Ventilation Mismatch Dr AHMED ESAWY
advantages of V/Q
• the arteries from the lingula remain the most
difficult to interpret by spiral CT due to their
small caliber
• unlike spiral CT, it has no absolute
contraindications
Dr AHMED ESAWY
Drawback of V/Q
• non conclusive results of intermediate probability category of the test.
• interobserver variability.
• False-negative lung scan interpretations tend to have nonocclusive subsegmental
• thrombi
Dr AHMED ESAWY
Other causes of V/Q mismatch in the absence of
positive V/Q study) include-(falsePE
• (1) who do not have acute PE is related to chronic or unresolved PE .
• (2) compression of the pulmonary vasculature (mass lesions, adenopathy, and mediastinal fibrosis);
• (3) vessel wall abnormalities (e.g. pulmonary artery tumors, vasculitis);
• (4) non-thromboembolic intraluminal obstruction (tumor emboli, foreign body emboli);
• (5) congenital vascular abnormalities (e.g. pulmonary artery agenesis or hypoplasia)
Dr AHMED ESAWY
Spiral / MDCT
Dr AHMED ESAWY
CT
• Contraindicated in cases of renal disease.
• Sensitive for PE in the proximal pulmonary
arteries, but less so in the distal segments.
Dr AHMED ESAWY
CT
• Quickly becoming the test of choice for initial
evaluation of a suspected PE.
• CT detect extraluminal non vascular abnormality
Dr AHMED ESAWY
• Accurate for segmental or larger PE
• Sensitivity 85 - 95% (Overall 50-60%)
• Specificity 90 - 100%
• Accuracy depends on interpreter
• Large Inter-interpreter variability
• Reduced accuracy with less experience
• Can identify other pulmonary etiologies
Pulmonary Embolism Diagnosis - Chest CT
Dr AHMED ESAWY
The diagnostic performance of
CT angiography for detecting
Subsegmental thrombi is lower
Dr AHMED ESAWY
technique
• A high-volume (100–150-mL) bolus
• 3-4ml / second
• 15–17-second scan delay
• 2-5 mm thickness
Dr AHMED ESAWY
CT Features OF PE
The cardinal sign of acute PE on CTPA is an
intravascular filling defect in a pulmonary artery
that partially or completely occluded the vessel
and is often associated with increased diameter
of the affected vessel.
Dr AHMED ESAWY
Helical CT Findings in Acute PTE
Vascular abnormalities
intraluminal filling defects
acute angles with the vessel wall
total cutoff of vascular enhancement
enlargement of an occluded vessel
Dr AHMED ESAWY
Ancillary signs of PE although non specific by themselves, can be helpful in case of subtle thrombus (Kazereoni and Gross, 2004).
Ancillary findings suggestive of acute PE include : - Pleural based wedge shaped areas of increased attenuation With no contrast enhancement - Linear atelectasis - An expanded, unopacified vessel. - Eccentric filling defects. - Peripheral wedge shaped consolidation - Oligemia. - Peripheral effusion.
Dr AHMED ESAWY
CT Findings in Chronic PTE
Cardiac abnormalities
right ventricular enlargement
right atrial enlargement
thrombi in the right atrium or ventricle
Vascular abnormalities
eccentric filling defect at angle with vessel wall
irregular or nodular arterial wall
abrupt narrowing of the vessel diameter
abrupt cut off distal lobar or segmental artery
recanalization of the thrombosed vessel
webs or bands (less frequent)
pulmonary abnormalities
bronchial artery dilatation
bronchiectasis
areas of decreased attenuation in the lung
(mosaic perfusion pattern) Dr AHMED ESAWY
extensive pulmonary embolism
Acute pulmonary embolism (PE) in
longitudinal section: the 'railroad track' sign.
the anterior segment right
upper lobe pulmonary
artery
the left
pulmonar
y artery
(curved
arrow)
right
pulmonary
artery
(black
arrowhead)
interlobar
artery
(white
arrowhead)
Dr AHMED ESAWY
extensive intraluminal filling
defects in both pulmonary
arteries (arrows),
thrombus extending into
segmental and subsegmental
branches (arrows).
Dr AHMED ESAWY
Acute pulmonary embolism (PE):
Pulmonary infarct.
Acute
lobar
segmental
right
lower
lobe
pulmona
ry artery
left lower
lobe
segmental
vessels
Dr AHMED ESAWY
calcification in the left pulmonary artery,
compatible with calcified thrombus (arrow) Chronic pulmonary embolism with
recanalization of thrombus.
right
descending
pulmonary
artery
Dr AHMED ESAWY
excellent degree of vascular enhancement
MDCT 80 ml contrast/ bolus triggering
Dr AHMED ESAWY
• Acute PE.
• partial filling defect in the anterior segmental
artery of the right upper lobe (arrow) Dr AHMED ESAWY
Acute PE.
medial segmental artery of
the right middle lobe
partial filling
defect in the
right lower lobe
artery
Dr AHMED ESAWY
Acute PE.
left lower lobe
pulmonary artery
Dr AHMED ESAWY
single-slice CT
Isolated filling defect in a
subsegmental pulmonary
artery of the external
segment of the right middle
lobe (arrow) Dr AHMED ESAWY
Massive acute, subacute and
chronic pulmonary embolism
Dr AHMED ESAWY
Right lower lobe segmental filling defect
with irregular edges
Left upper lobe posterior segment defect
occupying about 70% of the artery
Dr AHMED ESAWY
left main pulmonary artery
left upper, and lower lobe pulmonary
arteries. Another filling defect is seen in the
right interlobar pulmonary artery
Dr AHMED ESAWY
segmental branches of the left lower lobe pulmonary artery
Right lower segmental artery filling defects
Dr AHMED ESAWY
the right and the left lower lobe pulmonary
arteries
bifurcation of the left lower
lobe pulmonary artery
Dr AHMED ESAWY
Bilateral and extensive pulmonary embolism.
both right and left main pulmonary arteries
right upper lobe pulmonary artery.
A thrombus is also seen in the left lower
lobe pulmonary artery
left lower lobe, right middle and lower lobe
pulmonary arteries
Dr AHMED ESAWY
Multiple bilateral pulmonary embolisms.
right main pulmonary artery right lower lobe pulmonary artery
right and the left lower lobe pulmonary arteries Dr AHMED ESAWY
Pulmonary embolism An embolus is seen in the right lower lobe pulmonary artery
near just distal to its origin from the right interlobar pulmonary artery.
Dr AHMED ESAWY
pulmonary embolus in the right upper lobe pulmonary artery
Dr AHMED ESAWY
right lower lobe pulmonary artery (arrow).
Bilateral pleural effusion is also present.
Dr AHMED ESAWY
Pitfalls in Diagnosis of
Pulmonary Embolism with
Helical CT Angiography
Dr AHMED ESAWY
Causes of Misdiagnosis of
Pulmonary Embolism Patient-related Factors
• Respiratory Motion Artifact.—
• Image Noise.—
• Pulmonary Artery Catheter.—
Flow-related Artifact
Technical Factors Window Settings.—
• Streak Artifact.—
• Lung Algorithm Artifact.—
• Partial Volume Artifact.—
• Stair Step Artifact.—
Dr AHMED ESAWY
Anatomic Factors
Partial Volume Averaging Effect in Lymph Nodes.—
• Vascular Bifurcation.—
Pathologic Factors Mucus Plug.—
• Perivascular Edema.—
Dr AHMED ESAWY
Pitfalls of CT Angiography
Dr AHMED ESAWY
pseudo-filling defects.
Technique-related pitfalls include
• inadequate selection of injection parameters, such as
• flow rate,
• concentration
• scan delay,
• improper selection of the duration of the apnea,
Dr AHMED ESAWY
40-year-oldwoman with pulmonary embolism at level of left upper lobe parallelism and proximity of arteries and bronchi conversely to veins (straight arrows). Note pulmonary embolism at level of Subsegmental artery of apicoposteior segment (curved arrow).
Dr AHMED ESAWY
posterior and medial location of
venous return of apical segment of
inferior lobe(arrow).
confluence of vessel into inferior
pulmonary vein (arrow).
normal anatomy Dr AHMED ESAWY
pseudofilling defect
within pulmonary vein.
right inferior segmental arteries 60-year
intravascular area of low attenuation in
pulmonary vein(arrow).Medial
topography of vessel is well see in
B.Note respiratory artifacts. Dr AHMED ESAWY
variant anatomy of
lingular artery.
60-year
culminal artery(curved arrow)with anterior segmental artery at same level (straight arrow).
lingular artery (arrow) originating from culminal artery instead of left interlobar artery. Parallelism with lingular bronchus is well seen in B.
Dr AHMED ESAWY
Hilar Lymph Nodes and Perivascular Tissue
• 45-year-old woman with normal
• right hilar lymph located between intermediate Bronchus and right interlobar coulds simulate mural thrombus.
Dr AHMED ESAWY
enlarged lymph nodes
(arrows) in left hilum.
60-yearM
enlarged lymph nodes medial in relation to left
interlobar pulmonary artery with nodular shape
perivascular
nature of
hypodense
tissue
Dr AHMED ESAWY
Intersegmental lymph nodes
mimicking pulmonary embolism
a partially calcified lymph node mimicking a filling defect (arrow). Non-calcified lymph node is also demonstrated (arrowhead). A7 paracardiac segmental artery; A8 antero-basal segmental artery; A9+10 common trunk of latero-basal and postero-basal segmental arteries
The calcified lymph node (arrow) is well differentiated
from contrast-enhanced pulmonary arteries
Dr AHMED ESAWY
enlarged lymph nodes at culminal level.
50-year M
hypodensities lateral to
culminal artery (arrow) that
could correspond to lymph
nodes or marginal clot
perivascular nature of hypodensities (arrow, B) between artery and Bronchus (arrow, C).
Dr AHMED ESAWY
60-year-M
unilateral lymphangitis carcinomatosa.
areas of low attenuation (straight arrow) simulating pulmonary embolism.Visualization of vessel in transverse section (curved arrow) confirms perivascular topography of hypodensities.Note associated pleural effusion.
Dr AHMED ESAWY
area of low attenuation (arrow) projecting on anterior segmental artery of left upper lobe
because of partial volume deffect from lung parenchyma.This is well seen in B.
Pitfalls Related to Vessel Orientation
Dr AHMED ESAWY
hypodensities are related to vessel wall.
tortuosity of right main pulmonary artery
Simulating endoluminal abnormality.
70-year M
Dr AHMED ESAWY
Kinetic Artifacts
pseudofilling defect caused by motion artifacts.
pseudofilling defectat level of posterior segmental artery of right lower lobe (arrows)
on only one axial image.Respiratory motion artifacts are better shown on B
complete opacification of vessel (arrow) without any motion artifacts Dr AHMED ESAWY
pseudofilling defect caused by car diac and respiratory kinetic artifacts
generate intraarterial hypodense area simulating pulmonary embolism (arrow, A). These artifacts are well Seen in B.Note pleural effusion
Dr AHMED ESAWY
streak artifacts
flow-related artifacts from superior vena cava gener ating hypo- and hyperattenuated radiating images over right main and upper lobar pulmonary arteries.
65-year M
Dr AHMED ESAWY
under estimated pulmonary
embolism obscured by dense
surrounding contrast material
56-year M smal area of low attenuation (arrow) inri htinter lobar artery partially obscured by dense surrounding contrast material.
intraluminal clot (arrow)
Dr AHMED ESAWY
Insufficient Enhancement
• inadequate delay of injection
• too long a delay
• Delayed enhancement of the pulmonary
arteries can also be related to factors intrinsic to
the patient
• Insufficient contrast
Dr AHMED ESAWY
Nonthrombotic
pulmonary embolism
Dr AHMED ESAWY
Nonthrombotic pulmonary
embolism
• Septic Pulmonary Embolism
• Hydatid Embolism
• Fat Embolism
• Amniotic Fluid Embolism
• Tumor Embolism
• Air Embolism
• Talc Embolism
Dr AHMED ESAWY
Septic pulmonary embolism in a 28-year M
intravenous drug abuser with human
immunodeficiency viral infection
multiple cavitary nodules throughout both
lungs
the feeding vessel sign (vessel leading directly to
the nodule) in several nodules (arrows) Dr AHMED ESAWY
Septic emboli: metastatic lung abscesses
scattered thin-walled cavities
throughout both lungs, associated
with ill-defined areas of
consolidation in peripheral portions
of both lower lobes
Scattered nodules can be identified, both solid
and in various stages of cavitation /subpleural
feeding vessels are associated with many of
them (arrows), compatible with hematogenous
seeding in a patient with documented tricuspid
vegetations
Dr AHMED ESAWY
• pulmonary transplantation
• enlarged or engorged branches of the pulmonary arteries in the bilateral lower lung zones (arrows).
Pulmonary hydatid embolism caused by rupture of a mediastinal hydatid cyst into the right pulmonary artery 22-year-old F
Dr AHMED ESAWY
Fat embolism in a 58-year F
intramuscular injection of some fatty
materials into the buttock several
days earlier
bilateral ground-glass areas of increased opacity
widespread patchy ground-glass attenuation and
consolidation. A follow-up radiograph obtained 10 days
later (not shown) revealed complete resolution of the
ground-glass patterns Dr AHMED ESAWY
• left basal trunk shows multifocal tree-in-bud appearances
(arrows) caused by tumor emboli.
Pulmonary tumor thrombotic microangiopathy caused by metastatic gastric carcinoma in
a 57-year-old man
Dr AHMED ESAWY
• Talc embolism in a 37-year-old male drug abuser.
• left interlobar artery shows diffuse pulmonary involvement with ill-defined centrilobular small nodules (arrows). Note also the nodular branching structures (tree-in-bud appearance). Dr AHMED ESAWY
• widespread small pulmonary nodules with increased opacity, a finding that represents Cement embolism
Cement embolism in a 29-year-old F The patient had recently undergone cyanoacrylate embolization for intracerebral arteriovenous malformation
Dr AHMED ESAWY
Polymethylmethacrylate embolism
following percutaneous vertebroplasty in
a 64-year-old woman.
inferior portion of the left atrium shows radiopaque emboli in the segmental and subsegmental levels of the pulmonary arteries (arrows).
pelvic inlet shows tortuous paravertebral veins filled with polymethylmethacrylate (arrows). The vertebral body has been reinforced with this material.
Dr AHMED ESAWY
Other modalities
Dr AHMED ESAWY
Pulmonary Angiographic
• Angiography is the most definitive
technique for the diagnosis of PTE
However, because angiography is an
invasive technique, it is seldom performed,
even in major academic centers.
Dr AHMED ESAWY
Pulmonary angiogram
Dr AHMED ESAWY
Pulmonary Embolism Diagnosis - Pulmonary Arteriogram
Lobar Defect Normal Segmental Defect
Dr AHMED ESAWY
Acute pulmonary embolism on pulmonary
angiogram. A. Right and (B) left pulmonary
artery selective injections demonstrating
multiple filling defects (arrows) and vessel
cutoff sign (arrowheads)
Chronic pulmonary
embolism with stenosis.
Selective right pulmonary
angiogram demonstrating
segmental stenosis of the
right upper lobe pulmonary
artery (arrow) Dr AHMED ESAWY
101
MRA with contrast
Dr AHMED ESAWY
102
MRA Real Time
Dr AHMED ESAWY
MRI MR Angiogram
• Very good to visualize the blood flow.
• Almost similar to angiogram
3D Pulmonary MRA
Dr AHMED ESAWY
A B
Acute pulmonary embolism. Magnetic resonance
angiography demonstrates filling defect (arrow)
compatible with pulmonary embolism in the (A) right
and (B) left main pulmonary arteries
Dr AHMED ESAWY
Magnetic
resonance
angiography (MRA)
• relatively higher signal in the right pulmonary artery (arrows).
• (B) Close-up of contrast-enhanced fast gradient-echo image showing embolus in distal right pulmonary artery
Dr AHMED ESAWY
Ultrasound
• Duplex scanning with compression will
aid to detect any thrombus.
Highly sensitive and specific for
diagnosing DVT.
Look for loss of flow signal,
intravascular defects or non collapsing
vessels in the venous system
Dr AHMED ESAWY
D-Dimer Assays.
• Gainfully employed to select patients for further
radiological imaging.
• It is a cross linked fibrin degradation product and
a plasma marker of fibrin lysis.
• Serum level less than 500ng/L excludes PE with
90-95% accuracy.
• Unfortunately a positive test is non specific
(specificity only 25 – 67% and occurs in about
40 – 69% of the patients).
Dr AHMED ESAWY
Unreliable in presence of
• Malignancy.
• Sepsis.
• Recent Surgery.
• Recent Trauma
Dr AHMED ESAWY
THANK YOU
Dr AHMED ESAWY