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8/10/2019 CT Scan of Chest
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CT Scan of Chest
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CT scans of the chest are
very common examinations. performed for shortness of breath, chest pain,coughing up blood, and for the evaluation ofpossible cancer, biopsi.
These exams usually require intravenouscontrast but no oral contrast.
( Studies are performed with the feet entering thedonut or gantry first,) and scan time is
approximately 35 seconds
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CT Scan of Chest
CT scan of chest ordered without contrast
CT scan done
Small child - 4mm thick, 4mm spiral sections Large child- 8mm thick, 8mm spiral sections
CT scan done starting at thoracic inlet through bony
thorax, arms over head with normal breathing.
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CT scan starts with AI
and lateral scout and
film run to include:
Soft tissue windows Bone windows
Lung windows
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When dictated, impression should include but not
limited to:
Type of Pectus Excavatum
Mild
Moderate
Severe Hailer index and from what imagemeasurement was taken.
Hailer index is the transverse (coronal)measurement divided by the Al (sagittal)measurement at its deepest point.Measurements ~3~2 arc considered severe.
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Length of the deformity
Symmetty
Rotation/nonrotation of sternum
Cardiac impressions should Include but not limited to thepresence of the following:
Compression
Displacement
Distortion of shape
Puhnonary impressions should include but not limited to:
Compression
Presence of Atelectasis
Distortion of shape Skeletal (rib or vertebral) anomalies
Other organ involvement or skeletal defects that the pectusdeformity may have an effect on must also be noted.
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Emergency CT Examinations of the Chest
Two reasons for ordering an emergent chest CT that are clearlyappropriate are:
A patient is becoming septic and pus is suspected within thethorax.
A patient is suspected of having adissect ion
of the aorta.
Two reasons for ordering an emergent chest CT that are currentlystill under investigation are:
A patient is suspected of having a pulmonary embolism. A patient is suspected of having a t ransect ion of the aorta.
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Pulmonary Abscess
http://medinfo.ufl.edu/year2/bms5191/pulmon/images/08c.jpghttp://medinfo.ufl.edu/year2/bms5191/pulmon/images/08b.jpghttp://medinfo.ufl.edu/year2/bms5191/pulmon/images/08a.jpghttp://medinfo.ufl.edu/year2/bms5191/pulmon/images/08c.jpghttp://medinfo.ufl.edu/year2/bms5191/pulmon/images/08b.jpghttp://medinfo.ufl.edu/year2/bms5191/pulmon/images/08a.jpg8/10/2019 CT Scan of Chest
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Stanford Type "A"or a Type "B".
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If an aortic dissection is clinically suspected use the STAT chest
x-ray to exclude other causes that might mimic the signs and
symptoms of a dissection.
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Chest Trauma
Pneumothorax 69% (44/64) Cardiac Contusion 9% 6/64)
Lung Contusion 67% (43/64) Scapula Fracture 8% (5/64)
Rib Fractures 66% (42/64) Sternal Fracture 5% (3/64)
Hemothorax 28% (18/64) Diaphragm Injury 5% (3/64)
Flail Chest 14% ( 9/64) Vascular Injury 2% (1/64)
T-Spine Fracture 13% ( 8/64) Bronchus Fracture 2% /64)
Clavicle Fracture 13% ( 8/64)
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The role of CT controversial.
The advantages of CT
1) A negative CT scan excludes a significant number of patients whomight otherwise undergo an unnecessary and invasive procedure(mortality and morbidity risks for aortography are estimated at 1.7%-(1);
2) In the course of evaluating the patient for possible aortic dissectionwith CT, many other unsuspected findings not identified by plain
films are discovered including: pneumothorax, pneumomediastinum,pneumopericardium, thoracic spine fractures, sternal and manubrialfractures and other skeletal and lung trauma;
3) Using CT as a screening tool rather than the plain film to determinewho needs aortography has potential health care cost savings. cost
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The disadvantagesof using CT to screen patients for aortic injury1) Delay in obtaining the definitive aortogram or delays in taking the
patient to surgery while pursuing the CT may adversely affectprognosis in patients with aortic tears. (With the increased speed ofHelical CT and the widespread use of abdominal CT to survey amajority of blunt trauma victims, this disadvantage is debatable)
2) Mediastinal hemorrhage is fairly common after blunt chest trauma.Most of these patients will not have an aortic injury, but a few will.These patients then undergo two contrast studies, a CT and anaortogram, both of which are likely to be negative.
3) Few, if any surgeons, will operate based on the CT findings ofaortic injury without angiographic confirmation.
4) The utility of detecting branch vessel injury with CT is not known.Injuries to the great vessels occur in 1-2% of patients
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CT findings of aortic injury
mediastinal hemorrhage; aortic contour
deformity; intimal flap; thrombus protruding
into the aortic lumen; pseudoaneurym;
abrupt change in caliber of the descending
aorta compared with the ascending aorta(pseudocoarctation); and rarely contrast
extravasation.
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protocol Helical scanning mode with
8 sec spiral time; single-breath hold acquisition through the arch;
5 mm slice collimation reconstructed every 3 mm;
Pitch of 1.5-2; and 150 cc of intravenous contrast administered via injector at 3cc/sec. (a
50 cc saline chaser is used to wash out the remaining intravenous contrast in the I.V.line.)
Scanning begins at the level of the diaphragm and progresses cephalad to above thearch.
Smart prep to monitor contrast enhancement and the Spiral CT scan is begun whencontrast reaches the right ventricle.
After the aorta and chest are scanned, we immediately proceed to scan the abdomenand pelvis from the diaphragm down, having pre-programmed this second helicalacquisition.
Both axial images of the aorta and parasagittal LAO reformatted images through theaortic arch are evaluated for contour deformities and the presence of mediastinalhemorrhage.
Thin section CT is mandatory since most tears occur in the region of the ligamentumarteriosum. This area must be carefully scrutinized for hemorrhage or contour deformityon axial and parasagittal reformatted images.
Generate 3D images of the aorta which may be helpful to both angiographers (whentrying to confirm aortic injuries with aortography) and to surgeons in planning operative
repair. Fortunately, both 2D and 3D images, which take additional time to generate, are not
critical for detecting acute injuries.
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