Radiology

double wall sign; air on both luminal and peritoneal side; seen with PERFORATION of bowel

air in peritoneum abnormal unless patient had recent abdominal surgery

pneumomediastinum or pneumopericardium if lucency is above the diaphragm,

pneumoperitoneum if lucency is below the diaphragm.

3, 6, 9 rule: >3 cm for small bowel, > 6 cm for large bowel, > 9 cm for cecum

Symmetrical lung opacities; suggests:
-alveolar (obscures borders, usually bacterial)
– interstitial (does NOT obscure vessels or borders, usually viral) pulmonary edema

T1w – water is dark
T2w – water is bright
“In Terminator 1, he was a bad guy, so water is black. In Terminator 2, he was a good guy so water is white.”

IVC is anterior and to right of descending aorta

L common carotid artery is ANTERIOR to L subclavian artery

R common carotid artery is ANTERIOR to R subclavian artery

calcified pulmonary nodules + invasion of HILAR lymph nodes

usually in UPPER lobe

from PRIMARY TB infection

Seen on lateral radiograph; suggests PERICARDIAL EFFUSION

short parallel lines at the lung periphery; most common type of Kerley line seen

Causes: PULMONARY EDEMA, lymphangitis, malignant lymphoma, mycoplasma pneumonia, interstitial pulm fibrosis

pneumatosis of intestine (gas cysts in bowel wall). Suggests necrotizing enterocolitis

Overdistension of the appendix with mucous 2° to luminal obstruction by fecalith or foreign body, carcinoid or endometriosis

very rare, more common in females, mean age 55 yerars

narrowing of the terminal ileum in the right lower quadrant. The loop sits away from the other small bowel loops (“proud loop”) mostly because of surrounding fat.

CONGENITAL, nonfunctioning mass of normal lung tissue that lacks normal
communication with the tracheobronchial tree, and that receives its arterial blood
supply from the systemic circulation.

either intralobar or extralobar

Dx: ARTERIOGRAM (check systemic blood supply)
CT: solid mass that may be homogeneous
or heterogeneous, sometimes with cystic changes

Rare primary malignancy of bone
Originates from embryonic remnants of the notochord
50% in sacrum, 35% at skull b ase around clivas
Sx: LOW BACK PAIN
Imaging: large presacral mass (>10 cm) w/ displacement of rectum and/or bladder; MRI is modality of choice, but CT helpful in defining BONE DESTRUCTION
Tx: surgical resection, relatively radio RESISTANT

-most commonly from INFLAMMATORY conditions (eg granulomatous disease like TB)
in contrast echinoccoccus cysts have CURVILINEAR or RING calcification
-Benign neoplasms – hemangiomas
-malignant liver neoplasms: METS, intrahepatic, cholangiocarcinoma, fibrolamellar carcinoma, hepatocellular adenoma

see bowel gas in diaphragm

suggests croup (not emergency). In contrast, epiglottitis is a medical emergency.

Non-ossifying fibroma frequently reserved for lesions > 2cm in size in older children
usually children 2-15 years old

Migrate away from epiphysis towards diaphysis with age
Most lesions heal spontaneously by being replaced with normal bone

Cortical irregularity at the posterior, medial and distal femur deep to the attachments of medial gastrocnemius or distal adductor magnus

incidiental, ages 3-17; dis-spears after epiphyses close

middle-aged to older adults
Sx: PAINFUL SWELLING of knee
X-ray: soft tissue mass near articular surface; usually SPHERICAL and LOBULATED

X-ray: osteoporosis msot common, lesions usually MULTIPLE in verterbrae, ribs, skull pelvis, and femur

In spine, MM spares pedicle and destroys body

PP: Disturbance in sensation leads to multiple microfractures

Imaging: sclerosis, destruction of joints, soft tissue swelling, joint effusions, osteophytosis;
NO OSTSEOPOROSIS

Can due to spinal tumor (shoulder, hips (tertiary syphillis), diabetes (Feet, knees, hips)

suggests wedge-shaped lung infarct in PULMONARY EMBOLISM

suggests BRONCHIECTASIS

bronchus dilated compared to pulmonary artery branch (normally should be about the same size)

focal peripheral hyperlucency secondary to oligaemia => lack of vascular markings distal to PE

suggests PULMONARY EMBOLISM

prominent central artery that can be caused either by pulmonary hypertension that develops or by distension of the vessel by a large pulmonary embolus.

normal appearance of the lumbar spine when seen on oblique radiographic projection.

Break/decapitation of NECK OF DOG = spondylolysis (fracture of pars interarticularis)

Treatment for TB: surgical insertion of PLASTIC SPHERES into lung cavitary lesions by extrapleural stripping of tissues

CT: multiple SPHERICAL LUCENCIES in lung
CXR: multiple thin-waleld cystic spaces of equal size and wall thickness

CXR: CAVITATING MASSES with FLUID LEVELS

vasculitis affecting Upper and lower Resp. tract + kidneys; adults in FIFTH DECADE, no sex predominance

Sx: chronic sinusitis and UTI

Sx: fever, pleuritic chest pain
CXR: cavity with air-fluid levels, from PYOGENIC infections; segmental homogenous consolidation and subsequent cavitation
gram negatives (Pseudomonas, Klebsiella) cavitate more often than Staph.

most commonly from SQUAMOUS CELL lung cancer (rare in small cell LC) and usually affects UPPER LOBEs

PP: due to tumor growth outstripping blood supply => CENTRAL necrosis of neoplasm w/ thick and irregular inner lining

intralobar mass of disorganized pulmonary tissue that can exist with or without gross cyst formation

Cysts communicate w/ normal airways. 3 Types:
I = cystic (most common)
II = intermediate
III = solid (solid masses w/o gross cyst formation)

Energy: usually KV; higher energy = higher penetration; use HIGHER energy for thoracic spine x-ray than PA CXR

Current: usually milliamperes, the NUMBER of electrons hitting target; translates to radiographic DENSITY

Exposure time: too long exposure time => patient moves => BLURRING

Magnification: help demonstrate MINUTE details, especially BONES.

air < fat < soft tissue (=water density) < bone < contrast material (=metal density)

most abdominal x-rays are obtained AP (vs CXR, which are usually PA)

KUB is obtained SUPINE, but ureters are usually NOT seen unless contrast injected

undesirable deviation of x-rays produced by passage of beam thru objecting being examined => reduced detail

reduce scatter with BUcky-Potter grid => BUCKY VIEW

for MYELOGRAPHY, bronchography, lymphangiography, hysterosalpingography;

eg: pantopaque, dionosil (bronchography), ethiodol

for seeing CARDIAC CHAMBERS and blood vessels, urinary tract; also for GI cases if bowel perforation suspected

eg: GASTROGRAFIN for GI w/ suspected bowel perforation or large bowel obstruction

often given PO for opacification of GI tract

a PARTICULATE (suspension) substance; can cause ADHESIONS of getting into peritoneal cavity

do NOT give w/ suspected bowel perforation or LBO

one CXR on full inspiration, one CXR on full expiration

small PNEUMOTHORAX seen better with full EXPIRATION (can be missed w/ inspiration)

for pneumothorax, best seen on CXR that is UPRIGHT and EXPIRATORY

sharp detail in pre-selected PLANE of body
good for demonstrating CALFICIATION or CAVITATION in lung lesion

now replaced by CT

best for seeing APICES of lungs (patient leans back against cassette in exaggerated lordosis, or beam angled upwards)

lung BASES are also very distorted in this projection

contrast injected into pulmonary vessels through percutaneous puncture of vein in peripheral arm => catheter passed into main pulmonary artery

GOLD standard for diagnosing PE when V/Q scan or CTA fails

if asymptomatic: start at age 40 w/ mammogram and screen every 1 year in females

1/8 (12.5%) of women will get breast cancer
start earlier than age 40 or use MRI in conjunction
Use MRI if having BRCA mutation, strong FH, radiation to chest wall btwn age 10-30.

Standard = craniocaudal (CC) + medio-lateral-oblique (MLO) views

if BI-RADS 0, then get more detailed mammogram w/ additional views (eg magnification, 90 degree, compression, cleavage)

benign – looks like POPCORN calcifications

done WITH IV CONTRAST and sequential images and enhancement dynamics

Use MRI if having BRCA mutation, strong FH, radiation to chest wall btwn age 10-30.

SCREENING mammogram can only be read BI-RADS 0, 1, or 2.

0 = incompetence, need additional evaluation
1 = negative
2 = benign
3 = probably benign
4 = suspicious (4A = low, 4B = moderate, 4C = high)
5 = highly suggestive of malignancy
6 = known biopsy-proven malignancy

-10% of biliary stones + 90% of kidney stones contain enough calcium to become radio-opaque
-pancreatic calcifications (chronic pancreatitis)
-appendicoliths
-malignant kidney and GIT tumors
-atherosclerosis = plaque-like calcifcations in aorta and iliac vessels
-aneurysms

due to infectious GAS-FORMING organism in GI tract, usually E COLI

air in biliary tree; due to erosion of gallstone from GB into bowel (most commonly the DUODENUM)

can lead to SBO

MOTION picture of esophagus w/ contrast

for diagnosing ACHALASIA and SCLERODERMA (motility disorders)

also for observing cervical esopaghus, where barium passage is very rapid

helpful for diagnosing:
hiatal hernia = gastric mucosa above esophageal hiatus of diaphragm
Peptic ulcer = NICHE or OUTPOUCHING of contrast due to crater produced by ulcer
gastric cancer

helpful for diagnosing:
Celiac sprue
Crohn’s disease
Small bowel obstruction

barium introduced into RECTUM and flows RECTROGRADE to cecum

requires prep using LAXATIVE

do NOT give during suspected bowel perforation; if needed using WATER-SOLUBLE contrast

for diagnosing:
colon cancer
colon polyps
UC
diverticulosis (10% in people > age 50)
diverticulitis
LBO (give BE BEFORE giving small bowel series)

enema w/ BOTH BARIUM + AIR

can see smaller polyps (as small as 1-2 mm)

best diagnosed with ABDOMINAL U/S
if negative U/S but suspect acalculous cholecystitis or a false negative, give NUCLEAR MEDICINE BILIARY SCAN

contrast injected directly into biliary system, hopefully entering dilated biliary duct

differentiates btwn extrahepatic vs intrahepatic disease

failure to picture a biliary duct after several attempts => non-dilated ducts => jaundice NOT obstructive in origin

helps to avoid an unnecessary laparotomy

allows identification of TUMORS and GI bleeding (eg selectively via celiac trunk):
1) tumors have abnormal vasculature surrounding it due to increased blood supply, or displace normal vessels
2) GI bleeding => extravasation of contrast

diagnostic = dye injected into biliary system
curative = treatment of GALLSTONES

1) Plain abdominal x-ray (SCOUT film) => most renal stones are radio-opaque
2) IV contrast injected – shows calyces, renal pelvis, ureter, urinary bladder
Good for diagnosing:
-distortion of calyces
-dilation of calyces, renal pelvis, ureters
-filing defects (eg TUMOR, stones, blood clots)

However, CT WITHOUT CONTRAST is the imaging of choice for renal stone

similar to IVP, except contrast injected THROUGH urethra into bladder. Use if:
1) poor renal function
2) allergy to IV contrast material
3) poor visualization on IVP
4) equivocal (ambiguous) findings on IVP

Lytic: renal, thyroid, lung
Blastic: prostate
Lytic + blastic: breast

Radionuclide bones scans MORE sensitive than x-ray but less specific (aka gives more false positives).

dislocation = TOTAL disruption of a joint with no remaining contact
subluxation = PARTIAL disruption of joints with some remaining contact

Pathological fx = fracture through diseased bone (eg osteoporosis, cancer mets)
Stress fx = fx from repeated unaccustomed stress (fatigue fracture; eg tibia in athletes)

union = healing of fracture bone;
clinical union = resumption of motion of limb, and usually occurs BEFORE radiological union
mal-union = healing w/ deformity
non-union = failure of fx to heal by bone

S = Type I = Straight (eg SCFE)
A = Type II = Above
L = Type III = Low
T = Type IV = through or two
ER = Type V = erasure of growth plate or crush

CT is much more SENSITIVE than X-ray for detecting demineralization (eg osteomalacia, osteoporosis); for x-ray you need >30% demineralization before it can be seen, since CT shows loss of calcium much better

Uses MEGAHERTZ (>1,000,000 Hz) sound waves
-for pregnant women or study of fetus in utero
-for pleural fluid, kidney, gallbladder, biliary tree, pancreas, liver, newborn brain
-Emergency: acute cholecystitis, spleen rupture, tamponade, ectopic pregnancy

liver parenchyma vs mets to liver
liver parenchyma vs dilated bile ducts
renal parenchyma vs renal tumor
renal cyst vs renal tumor
brain tissue vs cerebral ventricles
normal brain vs brain tumor
normal brain vs cerebral hematoma

abnormally thickened greater omentum; infiltration of omental fat by soft-tissue density

-often from metastatic colon, gastric, ovarian cancer; can be from TB peritonitis, lymphoma

fusing of two kidneys into one and upward ascent

Technetium-99m half-life = 6 hrs, Gamma = 140 keV
-labeled RBCs for GI bleeding
-DISIDA or HIDA for biliary
-Pertechnetate for thyorid, salivary, Meckel
-Cardiac perfusion (under STRESS)
Iodine-123 half-life = 13.2 hr Gamma= 159 keV
-thyorid and pheo diagnosis
Iodine-131 half-life = 8.0 dy Gamma = 364 KeV
-thyroid ablation
Fluorine-18 half-life = 110 min Positron = 634 keV
Thallium-201 half-life = 73 hrs Gamma = 69, 81 keV
-cardiac perfusion (at REST)
Xenon-127 or 133
-lung ventilation

V/Q scan showing perfusion defect, ventilation defect, and CXR showing defect in same area.
Upper lobe = LOW probability of PE
Lower lobe = INTERMEDIATE probability of PE

Meds to DECREASE gastric emptying:
-glucagon
-pentagastrin
-cimetidine

Meds to INCREASE gastric emptying:
-metaclopramide

gas collection in subpulmonary location due to pneumothorax

PP: abnormal presence of air in abdominal cavity;
CXR: see FREE AIR under diaphragm

see air fluid level in lung

see dirty shadowing in gallbladder, and fluid and pus in GB

acute infection of GB wall caused by gas-forming organisms (eg, Clostridium or E coli)
-surgical emergency.
-gangrene
-perforation of the gallbladder
-high mortality

adhesions in liver; rare complication of pelvic inflammatory disease (PID); involves liver capsule inflammation => adhesions

Sx: acute onset RUQ pain aggravated by breathing, coughing, laughing

in lung on CXR, suggests a PLEURAL EFFUSION

on brain CT: suggests CLOT and impending stroke

suggests hyperparathyroidism

CT: punctuate lesions at gray-white junction. From SHEARING forces during trauma.

Classification for HCC:
LR-1 = definitely benign
LR-2 = probably benign
LR-3 = intermediate probability of HCC
LR-4 = probably HCC
LR-5 = definitely HCC

most often blurs RIGHT heard border (eg in segmental pneumonia)

Suggests BILATERAL PLEURAL EFFUSION

graduation transition from white (bottom) to grey to black (top of lungs); meniscus; blunting of CPh rececesses x2, blurring of diaphragm borders

-can be due to PRIOR HEMOTHORAX or PYOTHORAX
-can be due to ASBESTOSIS (more likely if BILATERAL PLEURAL PLAQUES)

PEG tube inserted into STOMACH
PEJ tube inserted into JEJUNUM
if aspiration pneumonia, must insert tube into jenjunum
feedings to jejnumum must more expensive than for stomach (cannot use home-crushed food)

A = long, unbranching, coursing out of hila to lung periphery; from distension of LUNG LYMPHATICS

B = short parallel lines at lung periphery; from INTERLOBULAR SEPTA

C = short, fine lines throughout lungs w/ reticular appearance due to thickening of anastomitic lymphatics of superposition of many Kerley B lines

due to SHEARING FORCES (eg during deceleration)
see punctate lesions on CT at GRAY-WHITE MATTER JUNCTION (since one is more dense than the other and more susceptible to the shearing forces)

T1w – good for ANATOMY; if w/ contrast, can also see tumors, infections, enhancement of pituitary + pineal gland
T1FS = T1w + fat suppression; good for OPTIC NERVE enhancement (eg in MS patient), since optic nerve normally sits in fat
FLAIR = similar to T1w, but abnormalities show up brighter since CSF signal usually SUPPRESSED
DW-MRI – can see infarct quickly (restricted diffusion)
T2w – most CNS pathology will be bright

appear iso-intense on T2w-MRI (though most CNS masses appear bright on T2w-MRI)

on MRI, will see CENTRAL AREA OF NON-ENHANCEMENT representing necrosis

1) loss of gray-white matter junction
2) cortical sulcal effacement
3) hyperdense vessel sign (acute thrombus)

PP: blood and air in chest/lung cavity; often secondary to cancer
Sx: SOB, chest pain
CXR: see air-fluid level in chest

Sx: SOB with no breath sounds in one lung
CXR: see AIR and lack of markings in one lung

combines BOTH CXR and abdominal x-ray (either one alone is not sufficient)

best way to make sure it’s in stomach (and not in left lung) is making sure it’s not cross the carina

10-15% have NORMAL CXR
90% will have abnormal CXR, but ~30% are non-specific findings:
Suggest PCP if CD4 < 200 and: -small pneumatoceles (air-filled cystic spaces), subpleural blebs -fine reticular interstitial pulmonary pattern -perihilar distribution -pleural effusion NOT common and only see in <5% of cases

SBO = SB dilated out of proportion to LB
LBO = LB dilated out of proportion to SB
ileus = LB and SB dilated in proportion to each other

maximal abdominal tenderness from pressure of the ultrasound probe over the visualized gallbladder

see HYPOechoic (darker) pancreas => necrotic tissue
-U/S not required for diagnosis, but only needed if amylase/lipase not elevated or want to check for gallstones
-CT WITH PO+IV contrast is the best modality for pancreatitis

calcified GB; must remove GB since high risk of cholangiocarcinoma

patchy opacities and widened airways showing bronchiectasis on CXR

DDx when ordering an enema: meconium ileus, atresia, Hirschprung’s, meconium plug syndrome (synonymous with small colon syndrome)

buckle fx = TORUS fx
nond-siplaced

PNET tumor; many systemic sx (eg fever, weight loss)
-plain film:
-permative, laminated (onion-skin) periosteal reaction, scelrosis; sometimes get Codman triangles, sunburst or thick periosteal reaction

ill-defined “fluffy” or “cloud-like”

due to PULMONARY FIBROSIS
(eg IPF, interstitial fibrosis, interstitial pneumonitis)
-silicosis

indicates endobronchial spread of some process; often can be infection (which fills ends of bronchioles), but in this case it is a bronchioalveolar carcinoma; it is NOT due to viral infection

nodules < 3 cm mass > 3 cm

CALCIFIED solitary pulmonary nodule more likely benign if:
1) central calcification
2) stippled calcification
3) complete calcification
More likely malignant if
1) IRREGULAR calcification

most common BENIGN nodule of lung; often contain foreign tissue like teeth, fat

(2nd most common lung nodule is post-infectious, such as post-TB)

-Renal disease w/ GFR < 60 mL/min -Diabetes -Multiple Myeloma -Renal transplant -Asthma attack within last 3 months -Planned thyroid ablation

severe form of DVT w/ possible gangrene and high risk of PE
underlying malignancy in 50% of cases

steroids, indomethacin, poor blood supply, osteonecrosis, anemia, malnutrition (Eg Copper, Zinc, Vitamin A deficiency, Vitamin D deficiency), diabetes, fragment distraction, old age, infection, motion, osteoporosis

air sickle due to LEFT UPPER LOBE lung collapse
air crescent’ which may be seen between the aortic arch and the medial border of the collapse.

RUL collapse with Golden S-sign – minor fissure is not flat because it is wrapping a mass; usually lung wrapping around lung cancer

collapse or incomplete expansion of pulmonary parenchyma. Note that the term “atelectasis” is typically used when there is partial collapse, whereas the term “collapsed lung” is typically reserved for when the entire lung is totally collapsed.

Lobar atelectasis indicated by:
1) air bronchograms
2) crowding of vascular markings
3) expansion of other lobes
4) elevation of diaphragms

1) Thoracic spine disc spaces should be barely visible through the heart.
2) The clavicular heads should be equal distance from the spinous process of the thoracic vertebral bodies.
3) Bronchovascular structures can usually be seen through the heart.

somewhat of a misnomer and in the true sense actually denotes the loss of a silhouette, thus, it is sometimes also known as loss of silhouette sign or loss of outline sign.

The differential attenuation of x-ray photons by two adjacent structures defines the silhouette, e.g. heart borders against the adjacent lung segments, and it is the pathological loss of this differentiation, which the silhouette sign refers to.

crescent of air in INVASIVE ASPERGILLOSIS => pulmonary necrosis

due to reabosorption of necrotic tissue causing retraction of inarcted center

complete white out of one lung
compensatory HYPERinflation of contralateral lung
-can be due to obstruction in mainstem bronchus

On CXR:
-patchy consolidation or poorly defined linear and nodular opacities
-more likely to cavitate than primary infections

high esophageal strictures or deep penetrating ulcers

intermittent partial or complete mechanical obstruction of the afferent limb of a gastrojejunostomy.

HCC most likely to enhance during ARTERIAL PHASE

non-contrast CT: often hypoattenuating relative to liver parenchyma

MRI: T1 = hypointense (darker) relative to liver
T2 = HYPERintense (brighter) relative to liver

pancreas wraps around duodenum

On abdominal radiograph:
-double bubble sign
-prenatal hydromnios
-minimal distal bowel gas

-infection of bile duct, usually from bacteria ascending for duodenum
-often in setting of bile duct obstruction
-Dx: ULTRASOUND is 1st line => dilated bile ducts; MRCP is better; ERCP is gold standard (also allows drainage)

10 cm long x 3 cm wide

helps to localize source of hemorrhage on CT scan
-areas with high attenuation (45-80 HU) more likely to be ACUTE clotted hemorrhage and thus indicate site of hemorrhage
-areas with lower attenuation (0-20 HU) indicate acute nonclotted hemorrhage or chronic hemorrhage

-bone fracture of the anterior and posterior arches of the C1 vertebra

Tx: halo immobilization for 12 weeks

allows better visualization of C7-T1 (obscured by clavicle on normal lateral x-ray)

-patient holds forearm in flexed position over the head, and the contralateral arm hangs to the side

fx of ANTERIOINFERIOR aspect of CERVICAL vertebral body

due to spine FLEXION + vertical axial compression

-often associated w/ spinal cord injury (often from displacement of posterior portion of verterbral body in spinal canal)

-fracture of both PEDICLES and pars interarticularis of C2
-often from NECK EXTENSION (Eg falls, MVA)

occurs where there is a fracture through the odontoid process of C2

from either flexion or extension of neck

OA:
-osteophyte formation
-reduced joint space
-subchondral sclerosis + cysts

RA:
-soft tissue swelling
-ill-defined marginal erosions (Vs osteophytes on OA)
-loss of joint space
-pericarticular osteoporosis

-DARK air-filled bronchi made visible by opacification of surrounding alveoli (grey/white)
-due to pulm consolidation, pulm edema, atelectasis