Seeing the signs of Radiology

Trevor Downing, MSIV

To quote Dr. Neuffer

• “These are the things Radiologists come up with when they sit in the dark too long…”

• Or something like that

Classic signs

Apple core sign

• Must r/o adenocarcinoma of colon • DDx:

– Malignant neoplasms (adenocarcinoma, lymphoma)– Benign neoplasms (villous adenoma)– IBD (chronic Crohn’s or UC)– Vascular disorders (ischemic colitis)– Infections (tuberculosis, helminthoma, ameboma)

• Studies of double-contrast barium enema as screening for colorectal cancer– Detects only ~1/2 of adenomas >1cm and 39% of all polyps.

May miss 15-22% of colorectal cancers– Use decreasing due to more accurate colonoscopy or CT

colonography

Bamboo spine

• Ankylosing spondylitis– Chronic inflammatory disease of the axial skeleton causing

back pain and progressive stiffness of spine– Peak age of onset 20-30yrs– Ankylosis refers to fibrous or bony bridging of joints– Part of the spondyloarthritis disorders – inflammation of the

entheses (insertion sites of ligaments on bones). – Dx:

• Clinical findings (inflammatory back pain, ↓ROM of back) • Lab testing – HLA-B27• Imaging

Bamboo spine

• Imaging– Abnormal SI joint on plain AP pelvic radiographs

seen in longstanding disease. • Findings: joint widening, erosions, sclerosis or ankylosis

– If no findings but suspicion is high then follow with MRI of pelvis.

– If MRI contraindicated then CT scan can detect erosions, bony sclerosis but not acute inflammatory changes

Champagne sign• Emphysematous cholecystitis

– US image reveals multiple tiny echogenic reflectors within the gallbladder lumen (arrows) corresponding to gas bubbles leaving from dependent wall.

– Often a complication of acute cholecystitis, caused by gas forming bacteria (mostly C. perfringens, Ecoli, gut bacteria)

– More common in men, elderly (>60yrs) and diabetics.

Champagne sign

• Emphysematous cholecystitis– Imaging

• Plain films may show air in wall/lumen• CT scan:

– GB wall thickening >3mm– Cholelithiasis– Increased bile density (>20H)– Loss of clear GB wall definition– Pericholecystic fluid (halo)

– Treatment• Percutaneous preoperative drainage + antibiotics

• Open cholecystectomy – laparoscopic less successful

Bat’s wings or butterfly appearance

• Congestive heart failure (HF)– Chest x-ray is often first diagnostic test

• Differentiates between HF and 1H pulmonary disease (dyspnea)

– Bat’s wings are bilateral perihilar edema– Findings suggestive of HF

• Cardiomegaly – cardiac:thoracic width >50%• Cephalization of pulmonary vessels• Kerley B-lines – pulmonary edema in interlobular septa• Pleural effusions

– Study of 880 patients showed• Cephalization, alveolar edema or interstitial edema all had >90%

specificity for HF• Cardiomegaly had only 50% sensitivity

Codman’s triangle• Osteosarcoma

– 1H malignant tumor of bone – malignant cells make osteoid or immature bone

– Uncommon tumor but #1 primary malignancy of bone in children and adolescents

• Bimodal distribution - <20yrs and >65yrs

– Most common sites• Children: metaphyses of long bones (distal femur 75%,

proximal tibia, proximal humerus)

• Adults: axial skeleton

Codman’s triangle• Osteosarcoma

– Risks• Prior irradiation/chemotherapy

• Paget’s disease – usually osteosarcoma in pts >40yrs

• Chronic osteomyelitis

• Multiple hereditary exostoses

• Fibrous dysplasia

• Metallic implants

• Hereditary retinoblastoma

• Li-Fraumeni syndrome (p53 mutation)

Codman’s triangle• Dx:

– First diagnostic test usually plain radiograph• Codman’s triangle new periosteal bone formation lifting

the cortex. • The associated sunburst appearance soft tissue

ossification.

– No bone findings are pathognomonic – biopsy needed

– DDx: • Malignant bone tumors (Ewing’s, lymphoma, mets)• Benign bone tumors (osteoid osteoma,

chrondroblastoma, osteochrondroma)• Non-neoplastic (osteomyelitis, eosinophilic granuloma,

bone cysts)

Hampton’s hump & Westermark’s sign

• Pulmonary embolus– Hampton’s hump

• Pleural based, wedge shaped consolidation represents area of infarction and atelectasis

– Westermark’s sign• Area of decreased density lateral to PE

represents oligemia distal to PE as well as distended/engorged pulmonary vessels.

Hampton’s hump & Westermark’s sign

• Pulmonary embolus– Radiographic abnormalities common in PE but not helpful

diagnostically

Strange signs

Anteater nose sign• Calcaneonavicular tarsal

coalition– Tarsal coalition abnormal

union or 2 or more tarsal bones– 2 most common types

• Calcaneonavicular• Talocalcaneal

– Causes are congenital or acquired

• Acquired: trauma, infection, surgery, articular disorders

Anteater nose sign

• Initial evaluation of tarsal coalition – conventional radiography– Oblique, AP and lateral weight bearing views

of feet– CT/MRI for complicated cases or preoperative

planning– MRI is useful for nonosseous fibrous or

cartilaginous coalitions

David Letterman sign(Aka Terry Thomas)

• Scapholunate dissociation (dislocation)– Most common and significant wrist ligament injury– Mechanism of injury:

• Similar to scaphoid fx – falling on outstretched hand (carpal loading)• Common in contact sports due to jamming extended hand into other

athletes

– Imaging• AP radiograph scapholunate distance >3mm & flexed scaphoid.• Lateral view increased scapholunate angle• MRI helpful

– In children: difficult to interpret due to incomplete ossification

– Incomplete tear of ligament

Mount Fuji sign• Tension pneumocephalus

– Causes• Iatrogenic: most commonly after neurosurgical evacuation

of subdural hematoma (2.5-16% incidence).– Other: skull base surgery, paranasal sinus surgery

• Non-iatrogenic: head trauma, nitrous oxide anesthetic, scuba diving?

– Mount Fuji sign useful test to distinguish tension from non-tension pneumocephalus

• Emergency surgery vs non-operative• Ishiwata study showed Mount Fuji sign positive in 4/5

patients with surgically confirmed tension pneumocephalus, not seen in any non-tension cases.

Yin-yang sign

• True and false aneurysm– Yin-yang sign due to partial thrombosis of aneurysm.

Contrast enhanced CT delineates lumen with active blood flow from the thrombosed portion

• Utility– Two studies showed 82 & 89% of aneurysms demonstrated

presence of mural thrombus.– This finding particularly helpful in 2 regions of body where

hard to differentiate from ddx• Brain: suprasellar meningiomas, craniopharyngiomas, hemorrhagic

metastases• Abdomen: cystic pancreatic tumors, islet cell tumors, solid/epithelial

neoplasms, pseudocysts, gastric leiomyomas and leiomyosarcomas– However, not a specific sign for aneurysms

• Rare solid or papillary neoplasms may show sign.

Throckmorton sign(John Thomas sign)

• Penis points towards the side of pathology– “The sign tends to be commented on by middle-

aged male radiologists and orthopedists suffering from Peter pan syndrome.”

• 2 studies– Medical Journal of Australia 1998 sensitivity

70%, specificity 67%– UK study sensitivity 30%, specificity 86%

• Mark Morton sign is a “smaller” Throckmorton

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subdural hematoma. J neurosurgery 1988; 68:58-61• Tommaso Lupattelli, The Yin-Yang Sign. Radiology March 2006 238:1070107110.1148/radiol.2383031884