Diagnostics- Radiology

AP positioning

A->P

taken from the front

ex: bedside

PA positioning

P->A

taken from the back

best for chest x-rays

Lateral positioning

From the pt side

Left -> Right

Decubitus position

x-ray taken while pt is laying on the side

best for looking at fluid layering

Oblique positioning

x-ray taken at a 45 degree angle

x-ray

white: opaque

(bone, metal, fluid)

CT

white: increased attenuation (hyperdense)

MRI

white: increased signal intensity

(fat, bone marrow)

nuclear medicine

white: increased tracer uptake

(tumor, bleeding)

barium studies

white: radioplaque

ultrasound

white: hyperechoic

(bone, gas)

frontal x-ray

A: airways (trachea, bronchi)

B: bones (clavicle, ribs)

C: cardiac (position and structures)

D: diaphragm (angle, elevation, effusion)

E: extras

lateral x-ray

retrosternal angle: the space behind the sternum (dark)

hilar region: triangular depression of the bronchus

fissures

-R/L major fissure only in lateral view

-R minor fissure in both lateral and anterior view

thoracic spine: should get darker more inferiorly

diaphragm

normal abdominal x-ray

air/fluid level:

no more than 2-3 in the small bowel

none in large bowel

distension is <2.5 cm small bowel and <6.0 large bowel

DISTENSION IS NORMAL

stool (appears cloudy)

abnormal abdominal x-ray

DILATION IS ABNORMAL

>2.5 small bowel and >6.0 large bowl

free air under the diaphragm (pneumoperitoneum)

calcification

ideal minimum # of view for plain films

chest: 2 (PA most ideal)

extremities: 2

spine: 3 (lateral most ideal)

X-ray

best uses: QUICK chest, abdominal, orthopedic pathology, foreign body, GI screening

benefits: portable and common

contraindications: none

limitations: less detailed

ultrasound (US)

best uses: superficial structures (ex: female pelvis), blood flow, "small structures"

benefits: cheap, low-risk

contraindications: none

limitations: deep structures are harder to view

CT

best uses: acute head pathology, abdominal/pelvic pathology, trauma, chest pathology, ortho workup

benefits: detailed

contraindications: radiation (impacts pregnant women) and possible allergy to IV contrast (CKD)

limitations: not portable

MRI

giant magnet, not portable

organ specific: brain, spinal cord, joints

white on MRI: fat, fluid

nuclear medicine

radioisotopes tagged to agents

NOT for pregnant

assesses function of organs, detect malignancy, evaluates for transplant rejection

black: increased radioactive uptake

interventional radiology

minimally invasive procedures using pictures

dilated large bowel

-uneven spacing, >6.0 cm

dilated small bowel

-"stack of pennies", >2.5 cm

Best modality for free air?

CT

How free air appears on plain film and CT

Best uses for US and CT in abdomen/ pelvis

US: "small parts" female reproduction, gall bladder, ectopic pregnancy, scrotom for torsion

CT: major organs, free fluid, bowel, cancer, trauma

Recognize the abdomen CT scan

-liver, spleen, colon, small bowel, aorta, kidneys, bladder

Mass in abdomen

Trauma in abdomen

obstruction in abdomen

-aka hernia

AAA

kidney stones

-don't use contrast

gallstone on US

-has shadowing behind

hydronephrosis on US

simple pancreatitis

needs no imaging (also UTI and hepatitis)

conditions that require imaging

-cholecystitis (US, NM)

-appendicitis (CT)

-diverticulitis (CT)

Appendicitis CT

Diverticulitis CT

For chest radiology, plain films are usually first

When to move onto CT:

-abnormal x-ray

-persistent infiltrate

-trauma

-pulmonary embolus

-aorta

-cancer work-up

Soft tissue v. Lung windows on CT

Identify chest CT anatomy

-lungs

-esophagus

-trachea

-major and minor fissures

-heart

-aortic arch

-ascending and descending aorta

-aorto-pulmonary (AP) window

-R and L main bronchi

lung structures as they pertain to heart borders

RML abuts R heart border

LUL (lingula!) abuts L heart border

Importance of spine appearance in evaluating lung pathology on a lateral chest x-ray

spine should get darker moving inferiorly and spacing between vertebrae should be even

doesn't get darker: opacity in LLL

cardiomegaly

opacities

could be due to: pneumonia, edema, blood, aspiration, tumor, atelectasis

effusions

-costophrenic angles blunted

-opacity with menisci

simple: respect gravity

lobulated: does not respect gravity

heart failure

-enlarged heart

-thickened fissures

-Kerley B lines

lung collapse/pneumothorax

-pleural border appears as white line

-AIR COMPRESSES

large PE

-clotting near heart

aortic dissection

-splitting into 2 lumens of aorta

A: ascending aorta

B: descending aorta

lung nodules/masses

hilar adenopathy

-swelling of lymph nodes in hilar region

AP window adenopathy

-swelling of lymph node in AP window

severe emphysema

-hyperinflated lungs

-flattened diaphragm

pneumoperitoneum

correct placement of ET tube, NG tube, and chest tube

common cause of pneumothorax

lung biopsy

Signs of traumatic aortic injury on x-ray and CT

-wide mediastinum

brain anatomy

-Frontal, parietal, temporal, occipital lobes

-Thalamus

-Cerebellum and brain stem

-Basilar, vertebrals, internal carotids, anterior, posterior, and middle cerebral arteries

-Normal appearance of gray and white matter

(gray is gray, white is darker than gray)

Epidural hemorrhage

-skull and dura mater

-confined by sutures

-can cross midline

-skull fracture

Subdural hemorrhage

-dura mater and arachnoid

-can cross sutures

-cannot cross midline

-trauma, elderly, child abuse(shaking)

Subarachnoid hemorrhage

-arachnoid and pia mater

-looks like it spreads out

intracranial mass: brain tumor

mass effect: lesion compresses surrounding brain tissue

midline shift: midline shifted to R or L

dense MCA sign

SUGGEST STROKE

Diffusion weighted imaging (DWI)

BEST FOR STROKE IDENTIFICATION

----CVA-----

core: infarcted brain tissue supplied immediately upstream of clot/aneurysm (DEAD)

penumbra: ischemic tissue upstream (CAN BE RECOVERED)

identify large clots on angiogram/ MRA/ CTA

aneurysm on MRI and angiogram

Relationship of aneurysms and subarachnoid hemorrhage

ruptured intracranial aneurysm can cause subarachnoid hemorrhage

Best test for evaluated bleeding in the brain

CT

spinal trauma imaging criteria

-age over 65

-history of malignancy

-pain lasting 6+ weeks

-significant trauma

-neurological deficit

x-ray: compression fractures, instability

CT: acute trauma, osseous injuries

MRI: the best- evaluates bone, soft tissues, discs, spinal cord, nerve roots

unstable fractures involves 2 columns

anterior column: anterior longitudinal ligament, anterior 2/3 columns

middle column: posterior longitudinal ligament, posterior 1/3 of vertebral body

posterior column: pedicles, articular facets, facet capsule, lamina, spinous processes, ligamentum flavum, interspinous ligament

recognize spinal column fractures

spondylosis

-osteophytes

spondylolisthesis

-translation

spondylolysis

-defect thru facet joint

DARK DISCS= DEGENERATIVE

Herniated disc

Protrusion: stays at level of the disc

Extrusion: extends past levels of disc

Bulging Disc

-extends evenly out of disc space

Compression fractures of the spinal column

Imaging modality of choice in MSK(musculoskeletal) trauma

x-ray

Identify epiphysis, metaphysis, and diaphysis

Location of scaphoid bone of the hand

damage can sever artery leading to it becoming osteonecrotic

When to do follow up imaging in trauma patients

important to ensure there are no persistent complaints

f/u when it isn't resolving

x-ray--> CT(some fractures)--> MRI(soft tissue/bone marrow)

comminuted

more than 2 fracture fragments

interarticular

if fracture reaches articular surface (joint)

if so, CT/MRI needed

displacement

movement of distal fragment relative to proximal

open

whether the fracture extends thru skin

long bone fractures- buckle/torus

-fracture without a cortical break

-common in kids

Salter Harris classification (Pediatric)

type 1: fracture thru physeal plate

type 2: fracture thru metaphyseal

type 3: fracture thru epiphyseal

type 4: fracture thru meta&episeal

Separation : acromioclavicular joint

Dislocation: glenohumeral joint

lisfranc fractures of the foot

-on medial cuneiform of 2nd metatarsal

-important to catch! can cause M2-M4 shift laterally