Radiology



Radiology 2004

Chapter 1

LIGHT RAYS

• Diff btn x-ray + lt rays is range of wavelength, x-rays r shorter than UV. Many substances that r opaque to lt r penetrated by x-rays

• Roentgen: 1895, unintentionally prod a hitherto unk form of radiant E that was visible, fluorescence (passed thru objects opaque to lt)

RADIOGRAPH

• Photons are produced from the – cathode ( tungsten which produces an + anion, anions emit to body and are recorded on the xray cassette a silver precipitates.

• Bombardment of unstable particles, destabilizes the Tungsten ( Xray is produced. (+) paper print made fr We view (-) films in class

RADIOPAQUE: more dense

• Radiolucent: more transparent

• Radiodensity/whiteness

• moist or solid/liquid-filled organs + tissue masses same density, > than fat or air but

< than bone or metal

• arrange in radiodenisty fr L. to ®: Pb > BaSO4 > Bone > musc > blood > liver > fat > air

• air = black on film

• bones = white

Chapter 2

PA FILM

• Always place Cx film as if u r facing the Pt (only possible w/ PA/AP views)

• CT scans and mammograms more radiation

• One day of sunlight is = 1 CXR

• PA is standard (L. lateral when you do PA can determine problem)

• AP is less satisfactory:

enlarged heart shadow, position of Pt is leaning bk, post ribs look more horizontal, diaphragm

higher, less lung volumes (b/c can’t take as deep a breath)

• Lateral Cx – 2nd MC (p PA); L. lateral made b/c the ♥ is closer to film…less magnified

• Lordotic view- apices; suspicion to TB, do AP, projects clavicles upward

• PA oblique to study ♥ or hila region

• Fluoroscopy – real time visualization of Pt’s, art/veins. Used during contrast exam of GI trat to follow course of barium thru esoph, stomach + bowel. Also for catheter placemt for angio procedures. During procedure, continuous beam of Xray passes thru ( image on screen. **Black + white r rev.; bone + contrast, dark; radiolucent lungs r white**

Angiography – IV of iodinated contrast agents *Allergy to iodine; arteriograms/venograms;

arterial sys usually opacified by contrast, done under fluoroscopic guide

• CT – cross-sectional slices, ID masses or bleeding, focused w/o superimposition. Range of densities (id conditions). Denser tissues – white (bone); less dense – dark; air is black. 5mm slices. Contrast media may b used to enhance diff densities (ie: GI, colonic)

• CT Angiography- form of 3D CT. vasc sys w/ short time of contrast; aortic aneurysms, dissection, stenosis, atherosclerotic plaques, Fx’s

• HI speed CT allow for uninterrupted scanning, Pt moves thru scanner, tube moves ~ Pt, 90sec.

• US – echogenic (solid) vs. anechoic (liquid); air + bone can’t b visualized well, 5 adv > CT; no ionizing radiation, no bio injury, any plane/direction, OB/GYN, pediatric, testicular, less $, portable & moving images. Disadv: more time than CT; technician-dependent

• MRI – no ionizing radiation, powerful magnet; 2D picture, imaging H+ atoms, fat & H2O molecules; bone is dark; White – strong signals, black – little signal or none (or gray). Compact bone, black; fat = brite white. Adv > CT; direct multiplanar scanning is possible.

• Radioisotope scanning – nuclear imaging; visualization of living organ via radionuclide injection. Chemical stays long enough for organ to b visualized; short ½ life to minimize radiation. Technetium – 99M is the MC; thyroid + lung.

**Bone scan is commonly requested, good for locating bone metastasis, detects Fx not seen on

Xray; sees bone healing itself; Ca will show where technetium collects

• PET – earlier detection of some cancer; reveals increased metabolic activity; heart- blood flow, Sx of CAD and Brain- suspected epilepsy; Alzheimer’s

Chapter 4

HOW TO STUDY THE Cx

• bony framework – inspect bones, joints, clavicles, ribs (in pairs)

• soft tissue

• lung shadows

• heart borders, left and right, diaphragmatic border

• hilar region

• parenchyma

• Check for symmetry, atrophy, increased mass, radiolucency/opaque pattern

Chapter 5

NORMAL Cx FILM

• Nml xpanded lung is largely radiolucent

• Underexposed- interpret misc shadows

• Overexposed- may blur out important shadows

• Normal lung markings- r bv’s, not bronchi/bronchioles; tracheobronchial tree can be visualized w/ radioopaque fluids- bronchography; (rarely used today)

• Lung root- R extend farther than L; R hilar slightly lower than L.

• Enlarged hila – engorgement of veins; obstrux in return of blood to heart; acute left ht failure after MI; chronically mitral stenosis- backup with pulm venous pressure; dilation of hila arteries – congenital heart disease (patent ductus arteriosus)

• Kerley B Lines- horizontal lines, thickening of interlobular septa, seen best in lower zones of lungs; Sx : edema, LAD, CHF, pleural effusion

• Blunted costophrenic angle- pleural effusion

• Thickened hila- superimposed with vascular vessels

• Hilar mass- most often due to lymph nodes, primary tumor masses – round, smooth outline, usually unilateral –cancer till proven otherwise

• Bilarteral- sarcoidosis or lymphoma

• Air space dz- alveoli, fill w/ fluid that displaces the air; appears white and radio-opaque, streaky

• Interstitial dz – distributed thru lung tissue that is otherwise well-aerated; produce linear or spherical densities patchy

• Clinical findings & Hx guide to Dx - ie: silicosis + eggshell calcifications

• CT – may show evidence of definite lung abnormality – help make more specific Dx

• HRCT- 1-1.5 mm thick slices, images are vastly superior > plain films

• Poorly aerated alveoli- crowded together, decrease radiolucency of lung;

Chapter 6

LUNG CONSOLIDATION/PULM NODULE

• Consolidations r solid airless masses, cast same density as ♥

• Massive – whole lung/ lobe attained soft tissue density ( airless

• Post. consolidation- can see ♥ better (silhouette sign)

• Pts w/ PNA consolidation in ®UL will blend w/ upper mediastinum + ®♥shadow but diaphragm + ↓®♥B r visible

Consolidation in 1 lobe

• Consol of U® + middle lobes will obscure ®♥B but ® diaphragm surf not obscured

• PA view the minor fissure can b seen as a thin line extending fr the hilum

• LLL consol in PNA will obscure the L. diaphragm in lateral view

• Diaphragm, pleural space, PE

Part of 1 lobe:

• Pt w/ patches of PNA in part of LLL, if ♥B is still visible…PNA isn’t anterior

• PNA + tumors both can prod solid areas in the lung

• Consol of lobar PNA thought of as “pure air-space dz”

• Airless lung will appear as consolidated but visible ∆ in size + shape of lung is indicative of collapsed lung

• In PNA + tumor: atelectasis, pleural fluid + primary consol of lung r common

Solitary and multiple Pulmonary Nodule

• Upon accidental finding of solitary nodule, get Pt’s previous films for comparison

• If nodule present for more than 2yrs + unchanged…benign, old granuloma

• If contains Ca centrally + very dense (white)…benign, old granuloma

• If no old films or nodule present, must take diagnostic measures…tissue sample, Bx

• Multiple nodules may indicate dz or inflamm condition, i.e. sarcodosis or histoplasmosis

Chapter 7

THE DIAPHRAGM

• Expiration – everything compressed upwards by diaphragm

• If u don’t take deep breath- can make an erroneous decision (ie cardiomegaly); lwr lung poorly inflated; giving appearance of abnormality

• ↑ diaphragm (ie ascites, sm/ lg bowel obstrux + distension, or 3rd trimester of pregnancy)

• flattens diaphragm (ie COPD, emphysema, air trapping, added volume (tumors, pleural fluids)

• when Pt is erect, stomach will b hi against the diaphragm

• any viscous containg air will appear dark shadow on film

• gastric buuble lies close against the diaphragm (this location is essential…if displaced, problem)

• L/R hemi-diaphragms @ level of 10th -11th rib

• False high hemidiaphragm due to a pneumonia blunting the diaphragm.

• Pleural effusion- blunted costal phrenic angles, white-out. Lateral decubitus – used to distinguish sm effusions

• Pneumothorax- lat decubitus is another way to visualize a sm pneumo b/c air in pleural space collect b/t air + Cx wall

• PE – abnl Cx film (ie diminished vol., linear or patchy segments of atelectasis, ↑ hemi-diaphragm on affected side, wester mark sign – localized areas of periph oligemia w/ or w/o distended pulm arteries) nml Cx film – new Cx pain + dyspnea.

• Hampton’s hump – infarctions appear as rounded opacities near the costophrenic sulcus

• 10% pt progress to pulm infarct

• pt with clinically suspected PE- VQ scan, arteriography is definitive

Chapter 8

Lung Overexpansion, Lung Collapse, Mediastinal Shift

• When lung tissue is inflated more than nml amt of air ( more radiolucent. ↑ radiolucency ( too dark, bv’s spread apart as they r separated farther by ballooned alveoli (in obstructive emphysema, this may be so exaggerated, can be confused with pneumothorax)

• Atelectasis ( Less Radiolucent. Will 1st b seen as a diff in density b/t 2 sides of the film.

• Poor inspiratory effort ( ↑ haziness, deep breath expands lungs

• Emphysema – overexpanded, diaphragm low, flattened + serrated. W/ fluoroscopy, will c diaphragm moves down slightly on inspiration + rtns very slowly on forced expiration. Develops into Pulmonary fibrosis ( web of filamentous strands of ↑ opacity seen

• Emphysematous bullae – huge air cysts w/I thin walls...enclose them. Rupture ( spont. Pneumo, CT is best Dx technique to ID bullae

Mediastinum

• 3 tag points- (PA view) air in trachea (visible as a dark vertical shadow), white knob of the aortic arch (left of spine at 5th rib), Rt heart border shadow

• If the whole lung collapses, all 3 tag points shift position, whole mediastinum swings to that side

• Hyperinflated lung pushes mediastinum over to opp side. Mediastinum must shift w/ ∆ in vol Massive pleural effusion, shifts to opp side.

• Tension pneumo – mediastinum shifts away fr affected side.

• Collapsed lobe- folds up fanwise against mediastinum.

• Elevation of the diaphragm compressing the heart will exaggerate the lateral projection of both heart borders (short and fat). Accuracy – count ribs to ensure diaphragm has been drawn down well. Tag points will appear displaced in a pt with a minor scoliosis.

• Total pneumonectomy- displaces mediastinum permanently.

• RUL collapse- hilum, trachea, aortic arch pulled up and to the right; lower and middle lobes expand to compensate for collapsed RUL

• LLL collapse- less heart shadow to rt of spine, dec in lucency of l. lung w/ preservation of l. hemidi; slightly elevated medially.

• Massive LLL collapse- little or no ht shadow seen to rt of spine; medial half of border of left diaphragm is missing, LLL is a wedge of opacity seen thru the heart, against the spine.

Chapter 9

MEDIASTINUM

• Aortic aneurysm causes trachea + esoph to shift right…anuerusm shifts left

• Mediastinum best seen on lateral film

• Ant. mediastin - masses seen in lat Cx film : goiter, thymoma, teratoma, lymphoma

• Middle mediastinal - posterior to ♥ structures: esoph, tracheo-bronchial tree, LNs

• Post mediastin - neural in origin, ganglioneuromas, neurofibromas, aortic aneurysms

• Superior- goiters, some extend ↓ into the mediastinum

• Paratracheal space - paratracheal stripe; slightly to rt of midline location of trachea. If widened – something’s there; could mean inflamm, mediastinal hemorrhage (iatrogenic), lymphoma, abscess in retropharyngeal space (infxtn travel down neck ( medistinitis)

THE ♥

• Plain – cardiac enlargmt, vasc abnorms, Calcifications, CHF

• Measuremt - cardiac width < ½ the thoracic width

• L. lat. film – routine, enhances plain films assay of ♥ size

• Pleural effusion - hazy, less lucent b/c of H2O

• Norm pulm vasc. on plain film – failing ♥, pulm venous engorgement, vessels extend farther than nml into lung field; appear as white rings (peribronchial cuffing)

• Kerley B – short horizontal white linear densities, close to peripheral margin of lung.

• Pulm edema- rapid accumulation of interstitial fluid spills over – developmt of alveolar pulm edema. Cx film + findings, but ♥ is nml in size (MI, sudden LV fail, maybe unequal bilat, batwing appearance about both hila (bathed in fluid)

• Nml pulm vasc – in upright nml, grtr at base than apex; b/c lung is pyramidal in shape

• Pulm HTN – venous- pattern: inc prominence + thickening of upper lobe, dec prominence of lower lobe, haziness in hilar

ABDOMEN

• Bones – spines, ribs, pelvis, upper femurs

• soft masses – border indicators, organ masses, fat lines, looking for calcification, shift in position, ∆ in shape

• Air in bowel – helps Dx

• Sm bowel – little to no air (w/o having just eaten)

• KUB = abd plain film; inaccurate b/c never see ureters on a plain film.

• Fat distributions w/i the abd will help you visualize structures they invest (kidneys).

• Calcifications- linear white margins,

• Plain film – Dx intraperitoneal free air, bowel obstrux, organomegaly, abnl masses + calcifications

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