Complete right-sided

pneumothorax

Lung is compressed

against mediastinum

Shift of heart and trachea to

left

Tension pneumothorax

Pneumomediastinum

Streaky, linear densities due

to air in the mediastinumStreaky, linear

densities due to air in the mediastinum

Pneumomediastinum – CT scan

Air surrounding esophagus in mediastinum

Extraluminal contrast from

perforation along left

lateral wall of distal

esophagus

Pneumoperitoneum

Air outlines under surface of left hemidiaphragm

Air outlines under surface of

right hemidiaphragm

Pneumoperitoneum

Air outlines both sides of the wall of the stomach-a sign of free air in

the peritoneal cavity

Pneumoperitoneum - CT

CT scans on 2 different people show a small and large amount of free air in the peritoneal cavity which rises to the highest point (anterior abdomen with the

person lying on their back) and is not contained within bowel

Free airFree air

Effect of Position - Layering

Supine Erect

In the supine position, the fluid layers out posteriorly and produces a haziness, especially near the bases (since the patient is actually semi-

recumbent). In the erect position, the fluid falls even more to the bases.

Pulmonary Venous Hypertension from Mitral Stenosis

Size (not number) of vessels at the apex exceeds size of vessels at the base in this upright person. This is called “cephalization.” Normally the vessels at the base exceed the size of the vessels at the apex

Pulmonary Interstitial Edema

Pulmonary interstitial edema produced by Kerly A and C lines

Pulmonary Alveolar Edema

Bilateral, diffuse airspace disease more marked centrally than at the periphery of the lung (“bat-wing appearance”)

Aortic Dissection

Linear lucency in the contrast-filled descending aorta is the intimal flap of an aortic dissection

Aortic Dissection

• Widened mediastinum

• Left pleural effusion

• Chest pain

Should make you think of an aortic dissection

Classification of Dissecting Aneurysms

Stanford classification

• Widened mediastinum

• Left pleural effusion

• Chest pain

Aortic rupture

Red arrows point to active extravasation of contrast from the aorta into the retroperitoneum

Thrombus inside the lumen of the aorta

Red arrows point to active extravasation of contrast from the aorta into the retroperitoneum

AortaAorta

Ruptured Aortic Aneurysm

Enlargement of abdominal aorta > 3cm Usually 2 to atherosclerosis Below renals, above iliacs

About 20-25% rupture <4cm~10%; >10 cm~60% Retroperitoneal, usually on left Into GI tract: massive hemorrhage Into IVC: rapid cardiac decompensation

Diaphragmatic Rupture

Left hemithorax contains multiple lucencies--air in the lumen of bowel, now located in the chest

Heart and trachea are

displaced to right by bowel in

opposite hemithorax

Diaphragmatic RuptureGeneral

5% of all diaphragmatic hernias Most (90%) are left-sided

Central and posterior >10cm in length Contain stomach, colon, small bowel,

omentum, spleen

Half have no initial abnormal radiographic findings

Half are missed clinically

36 year-old with acute abdominal pain. Why?

Small Bowel Obstruction

Multiple air-containing and dilated loops of

small bowel

No gas in rectosigmoid

Multiple air-fluid levels

in small bowel

Sigmoid Volvulus

Sigmoid twists around this point

Obstructed, dilated sigmoid has a “coffee-bean” shape

Cecal Volvulus

Dilated loop in LUQ is cecum which has twisted on itself

Dilated loops of small bowel from small bowel obstruction at ileocecal valve

Sigmoid Volvulus – Barium Enema

Cecum twists at this point

producing “Bird’s-Beak”

sign

74 year-old with change of bowel habits

Large bowel obstruction – Sigmoid carcinoma

Dilated loops of large bowel with abrupt cut-off in

sigmoid

Barium enema shows annular constricting carcinoma of sigmoid producing obstruction

Rectum

Dilated large bowel

Ascites

Ascites

Ascites is lower in attenuation than adjacent, contrast-enhanced liver

R3

Massive ascites on CT

Massive ascites (red arrows) in a patient

with a pseudocyst of the pancreas (green

arrow)

R3

Tip of central venous catheter coils back on itself in right brachiocephalic vein (red arrow).

Tip of endotracheal tube is in right mainstem bronchus (red arrow) leading to atelectasis of the right upper lobe and entire

left lung

Traumatic intracranial hemorrhageEpidural Hematoma

Crescentic area of increased attenuation on non contrast-enhanced CT with convexity toward brain is characteristic of an epidural hematoma

Traumatic intracranial hemorrhage Subdural hematoma

Crescentic low attenuation lesion at periphery of brain containing a fluid-fluid level from blood

Traumatic intracranial hemorrhage Intraparenchymal hemorrhage

Intraparenchymal hemorrhage

Subarachnoid hemorrhage from ruptured aneurysm

R3 R3

Acute hemorrhage in the basilar cisterns (red arrows) and Sylvian fissures (green arrows) in two patients with ruptured aneurysms

Colloid Cyst of 3rd ventricle producing obstructive hydrocephalus

R3

Markedly enlarged

frontal horns Colloid Cyst obstructing third ventricle

Choroid plexus (normal)

Hydrocephalus from Choroid Plexus Papilloma

R3

Lateral ventricles – anterior and

posterior horns

Large mass represents a choroid plexus papilloma

Hydrocephalus from Cerebral Atrophy

Lateral ventricles – anterior and

posterior horns

58 year-old woman with breast cancer and headache

Fracture through posterior

elements of C2

Forward displacement of the body of C2 (red arrows)

Spinolaminar white line of C2

does not align with other

vertebral bodies

Fracture of C2 - “Hangman’s Fracture”

A A

Hangman’s Fracture

l Most common fracture of C2 n Most common cervical spine fracture

l Hyperextension/compression fracture

l Fractures through the pedicles of C2 with anterior slip of C2 on C3

l Not associated with neuro deficit

Locked facets

The inferior

articular facet of

C5 (red arrow) has

slipped forward

and lies anterior to

the superior

articular facet of

C6 (green arrow)

— a condition

known as a

“locked facet”

C5

C6

B

Fractures of the metaphysis (red arrow) and epiphysis (green arrow) (Salter-Harris IV) extend into joint

Fracture of radial styloid (yellow arrows) extends into wrist joint5

Fractures extending into joints

Posterior “fat-pad sign” indicates fluid in the joint

Fracture of radial head

Fracture of the radial head with traumatic joint effusion

Anterior Dislocation of the Shoulder

2

Humeral head (red arrow) lies inferior to the coracoid process of the scapula (green arrow)

Humeral head (red arrow) lies inferior to the glenoid fossa of the scapula (yellow arrow)

Humeral head (red arrow) lies inferior to the coracoid process of the scapula (green arrow) and anterior to the glenoid (yellow oval)

Posterior Dislocation of the Shoulder

1

Humeral head (red arrow) lies posterior to the glenoid fossa of the humerus (yellow arrow)

Humeral head (red arrow) lies beneath the acromion process of the scapula (green arrow) and posterior to glenoid (yellow oval)

Humeral head (red arrow) assumes the shape of a “lightbulb” because it is fixed in internal rotation