Transcript Principles of Radiology

Principles of Radiology
Daniel Podd RPA-C
Physics of Radiology
 X-Rays produced by electron beam
hitting tungsten film target
 Electrons strike film, metallic silver is
precipitated if no obstruction to beam,
resulting in bright film
 Obstruction in path of beam prevents
silver precipitation; film remains dark
 The negative of this film is known as
the Plain X-Ray, or radiograph
Positive
Negative (Developed)
Radiograph, “Plain Film”
Radiodensity as a Function of Thickness
Radiodensity as a Function of
Composition with Thickness Kept
Constant
X-Ray
A-D:
Radiolucent or
Radioopaque?
Why?
AP CHEST: Patient Position
AP CHEST
PA CHEST: Patient Position
L: Lung
R: Rib
T: Trachea
AK: Aortic
knob
A: Ascending
aorta
H: Heart
V: Vertebra
P: Pulmonary
artery
S: Spleen
Lateral
Bullet + PA only = ?
Bullet + PA & Lateral =
PA Chest
Lordotic
View
Fluoroscopy
Mechanism: Continuous X-ray beams from
below patient, amplified by intensifier
above patient;
broadcast on highresolution television
screen
 Provides live animation
 Imaging reversed vs xray
 Uses: Barium swallow to evaluate esophagus,
small and large intestines, vessel catheter guidance
Fluoroscopy
Spot Film:
Single X-ray
during
procedure.
Film
developed
into negative
Angiography
Mechanism: Uses X-rays and intravascular
injection of iodinated contrast to evaluate
arterial (arteriogram) and venous
(venogram)
systems
 Vasoocclusive
disease
 Most approaches
via femoral artery
or vein
Computerized Axial Tomography
 Cross-sectional slice radiographs of the
body using thin beam of X-rays
through desired axial plane
 Slices up to 1.0 mm that represent
density values; no superimposed
images
 Viewed as if facing patient and looking
up through feet
 Density Less Dense: Air, Fat (black)
More Dense: Bone (white)
CT Scan
CT Scan Angiography
 3DCT, 3-Dimensional CT scan
 Injection of IV contrast to enhance
vascular system
 Useful for aortic aneurysms, coronary
heart disease, carotid vascular
occlusive disease
CT Scan Angiography
Ultrasound
 Mechanism: High-frequency sound
waves beamed directed into body, onto
organs and their interfaces; transducer
receives and interprets reflection of
these beams from organs
 Acoustic Impedance: beam absorption
by tissues, based on density and
velocity of sound through different
adjoining tissue types
Ultrasound
 Image (echo) produced when different
neighboring tissues reflect different
acoustic impedances
 Solid organs, fat, & stones: Echogenic
(white)
 Fluid & cysts: Anechoic (black)
Ultrasound
Ultrasound
Advantages
1. No ionizing radiation
2. Applicable to any plane
3. Cost-effective
4. Portable
5. Real-time imaging
Disadvantages
1. Time consuming
2. Poorer quality
Magnetic Resonance Imaging (MRI)
 Mechanism: Patient placed in magnet
tunnel; radio waves passed through body in
pulses. Pulses returned from tissues,
transformed into 2D image based on relaxing
times: T1 & T2
T1
T2
High Signal (brightness) Low Signal
fat,
blood (gray), solid
medullary bone
mass, cysts, air,
compact bone
tumors, solid
compact bone, blood,
masses, CSF, cysts fat, air
MRI
Advantages vs CT:
1. Multiplanar scanning
2. Better soft-tissue differentiation
3. Contrast-free 3DMR
Contraindications:
Metals, clips, pacemakers
MRI
T1
T2
Normal
CXR
Normal
CXR
Enlarged
Hila
Aortic Knob
Hilar Mass
(Left)
Right vs Left Pulmonary Artery
Kerley B-Lines
• Fine horizontal
opacified
lines representing
pulmonary edema
• Seen in CHF,
pulmonary fibrosis,
heavy metal
fibrosis,
malignancy
Blunted Costophrenic Angle
Lung Mass: Cavitation
Lung Mass: Solid Tissue
Air Space (Alveolar) Disease
Interstitial Disease
Alveolar or Interstitial?
Alveolar or Interstitial?
Alveolar or Interstitial?
Lobar Consolidation: Right
• Think anatomically
3 Lobes
 RUL and RML located
Anterior to heart
 Obliteration of
mediastinum and cardiac
borders
 Right CoPhS intact
 RLL located Lateral to
heart, but anterior to
diaphragm
 Obliteration of right
CoPhS
 Right heart border
intact
Lobar Consolidation: Left
 LUL lies anterior to  LLL located lateral
heart and superior
to heart and
to diaphragm (and
anterior to
LLL)
diaphragm
 Obliteration of left  Obliteration of left
heart border only
hemidiaphragm
 Left
 Left heart border
hemidiaphragm
intact
intact
Where Is This Consolidation?
Diaphragm
Gastric Bubble
Diaphragm: Expiration vs
Inspiration
Pleura
 Anatomically, the visceral and parietal
pleura are separated by a potential
space, the pleural space
 Fluid in this space is known as a Pleural
Effusion
 Effusions may be large or small, but
settle to base of lung due to gravity
 Completely obscures aerated lung and
heart/mediastinum/diaphragm borders
Pleural Effusion: Large
Pleural Effusion: Small
Pleural Effusion: Small (special case)
Pleural Effusion: Small (special case)
Pneumothorax
 Introduction of air into the normal vacuum
of pleural space
 Radiographic findings:
1. Hyperlucent versus aerated lung
2. Passive atelectasis of ipsilateral
lung
3. Depression of ipsilateral
hemidiaphragm
4. Mediastinal shift
Pneumothorax
Optimal Radiographic Images:
1. Expiration film
2. Lateral decubitus film
Pneumothorax
Subtle Pneumothorax
Pulmonary Embolism
 Lung vessel embolus
 Radiologic findings:
1. Diminished lung volume
 Elevated ipsilateral
hemidiaphragm
 Linear/patchy ipsilateral
atelectasis
2. Completely Normal ! (m/c)
 CXR to rule out other etiologies
Pulmonary Embolism
Pulmonary Embolism
With Infarction:
1. Hampton’s Hump
Pulmonary Embolism
Further Diagnostics
 Perfusion Test (Q)
 Ventilation Test (V)
 Technetium-99
 Xenon gas
Perfusion/Ventilation mismatch, “V/Q Mismatch”
Pulmonary Embolism
 V/Q Scan Interpretation
1. Normal Perfusion scan =Rules out PE
2. Negative/Low Probability scan (slight
perfusion abnormality or V/Q matching)=
Non-embolic pulmonary abnormalities
3. Positive/High Probability= V/Q mismatch
4. Intermediate/Indeterminate = Low & High
Pulmonary Angiogram indicated for 3, 4, or 2
with strong clinical evidence
Pulmonary Angiogram
 Gold
Standard
Helical (Spiral) CT Scan
 Indicated for suspected PE with
abnormal CXR
 CT venogram: Adding IV contrast for
concurrent deep leg vein scan
References
http://www.vh.org/adult/provider/radiology/icmrad/chest/parts/Right
hilum.html
http://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/at
las/cxratlas_f.htm
http://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/at
las/hilar.htm
http://uwcme.org/site/courses/legacy/threehourtour/edema.php
http://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/at
las/apwindow1.htm
http://info.med.yale.edu/casebook/intmed/manditi/test_results.html
http://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/at
las/normallabeled.htm
http://www.premedonline.com/Personal_Page/rad.html
http://sfghed.ucsf.edu/ClinicImages/chest_and_pelvis_films.ht
m
http://www.virtual.epm.br/material/tis/currmed/med3/2003/ddi/matdid/cap2.htm
References
http://www.virtual.epm.br/material/tis/currmed/med3/2003/ddi/matdid/cap1.htm
http://www.fhsu.edu/nursing/cxr/CostoPhrAngCopy.htm
http://www.aic.cuhk.edu.hk/web8/0122_CONSOLIDATIO
N_LATERAL_SEGMENT_RML.jpg
http://www.med.wayne.edu/diagRadiology/TF/Chest/CH0
4.html
http://acbrown.com/lung/Lectures/RsVntl/RsVntlMsclDp
hr.htm
http://www.nyp.org/masc/images/nl3_ph11.jpg
http://www.lumen.luc.edu/lumen/MedEd/medicine/pulmo
nar/images/effusion.jpg
http://brighamrad.harvard.edu/Cases/bwh/hcache/116/full
.html
http://www.radiology.co.uk/srs-x/cases/094/a.htm
References
http://brighamrad.harvard.edu/Cases/bwh/images/84/R54A2.GIF
http://uwcme.org/site/courses/legacy/threehourtour/images/PTXPA.jp
g
http://www.med.wayne.edu/diagRadiology/TF/Chest/CH08.html
http://www.nature.com/ncpcardio/journal/v2/n2/thumbs/ncpcardio01
18-F2.jpg
http://www.vh.org/adult/provider/radiology/icmrad/nuclear/parts/HiP
rob.html
http://www.rochestermedicalcenter.com/images/a015.jpg
http://www.engineering.uiowa.edu/~bme185/angiogram.gif
http://www.vh.org/adult/provider/radiology/ElectricPE/RadImages/03
.RT-Angio.gif
http://www.usask.ca/medicine/imaging/Clinical/GF.shtml
http://health.allrefer.com/pictures-images/pancreatic-cysticadenoma-ct-scan.html
http://www.mia.net.au/perrett/info_general/ct_angio/Image2.jpg
http://www.terarecon.com/gallery/images/us_7_gallstones.jpg