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 =

                             

    

Lordotic View

PA Chest

FluoroscopyMechanism: Continuous

below patient, amp- lified by intensifier above patient; broadcast on high-resolution television screen

Provides live animation Imaging reversed vs xray Uses: Barium swallow to evaluate esophagus, small and large intestines, vessel catheter guidance

X-ray beams from

Fluoroscopy

Spot Film: Single X-ray during procedure.Film developed into negative

AngiographyMechanism: 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

UltrasoundAdvantages

1. No ionizing radiation

2. Applicable to any plane

3. Cost-effective

4. Portable

5. Real-time imaging

Disadvantages1. Time consuming2. Poorer quality

Magnetic Resonance Imaging (MRI)

T1

T2

fat, medullary bone

blood (gray), solid mass, cysts, air, compact bone

tumors, solid masses, CSF, cysts

compact bone, blood, fat, air

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

High Signal (brightness) Low Signal

MRIAdvantages vs CT:

1. Multiplanar scanning

2. Better soft-tissue differentiation

3. Contrast-free 3DMR

Contraindications:

Metals, clips, pacemakers

MRI

T1 T2

Normal CXR

NormalCXR

EnlargedHila

Hilar Mass(Left)

Aortic Knob

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 heart and superior to diaphragm (and LLL)

Obliteration of left heart border only

Left hemidiaphragm intact

LLL located lateral to heart and anterior to diaphragm

Obliteration of left hemidiaphragm

Left heart border 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

Perfusion Test (Q) Technetium-99

Ventilation Test (V) Xenon gas

Further Diagnostics

Perfusion/Ventilation mismatch, “V/Q Mismatch”

Pulmonary Embolism V/Q Scan Interpretation 1. Normal Perfusion scan =Rules out PE2. Negative/Low Probability scan (slight

perfusion abnormality or V/Q matching)= Non-embolic pulmonary abnormalities

3. Positive/High Probability= V/Q mismatch4. 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

Referenceshttp://www.vh.org/adult/provider/radiology/icmrad/chest/parts/Righthilum.htmlhttp://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/atlas/cxratlas_f.htmhttp://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/atlas/hilar.htmhttp://uwcme.org/site/courses/legacy/threehourtour/edema.phphttp://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/atlas/apwindow1.htmhttp://info.med.yale.edu/casebook/intmed/manditi/test_results.htmlhttp://www.meddean.luc.edu/lumen/meded/medicine/pulmonar/cxr/atlas/normallabeled.htmhttp://www.premedonline.com/Personal_Page/rad.htmlhttp://sfghed.ucsf.edu/ClinicImages/chest_and_pelvis_films.htmhttp://www.virtual.epm.br/material/tis/curr-med/med3/2003/ddi/matdid/cap2.htm

Referenceshttp://www.virtual.epm.br/material/tis/curr-med/

med3/2003/ddi/matdid/cap1.htmhttp://www.fhsu.edu/nursing/cxr/CostoPhrAngCopy.htmhttp://www.aic.cuhk.edu.hk/

web8/0122_CONSOLIDATION_LATERAL_SEGMENT_RML.jpg

http://www.med.wayne.edu/diagRadiology/TF/Chest/CH04.html

http://acbrown.com/lung/Lectures/RsVntl/RsVntlMsclDphr.htm

http://www.nyp.org/masc/images/nl3_ph11.jpghttp://www.lumen.luc.edu/lumen/MedEd/medicine/pulmonar/images/effusion.jpghttp://brighamrad.harvard.edu/Cases/bwh/hcache/116/full.htmlhttp://www.radiology.co.uk/srs-x/cases/094/a.htm

Referenceshttp://brighamrad.harvard.edu/Cases/bwh/images/84/R54A2.GIFhttp://uwcme.org/site/courses/legacy/threehourtour/images/

PTXPA.jpghttp://www.med.wayne.edu/diagRadiology/TF/Chest/CH08.htmlhttp://www.nature.com/ncpcardio/journal/v2/n2/thumbs/

ncpcardio0118-F2.jpghttp://www.vh.org/adult/provider/radiology/icmrad/nuclear/parts/

HiProb.htmlhttp://www.rochestermedicalcenter.com/images/a015.jpghttp://www.engineering.uiowa.edu/~bme185/angiogram.gifhttp://www.vh.org/adult/provider/radiology/ElectricPE/RadImages/03.RT-Angio.gifhttp://www.usask.ca/medicine/imaging/Clinical/GF.shtmlhttp://health.allrefer.com/pictures-images/pancreatic-cystic-adenoma-ct-scan.htmlhttp://www.mia.net.au/perrett/info_general/ct_angio/Image2.jpghttp://www.terarecon.com/gallery/images/us_7_gallstones.jpg