August 27, 2010

Upper Extremity Deep Vein Thrombosis

An ultrasound image shows an echogenic thrombus and absence of color flow in the right axillary veins (arrows).

Facts: Upper Extremity Deep Vein Thrombosis
  • Secondary form (more common) is believed to be due to intimal injury, venous stasis and hypercoagulability. Primary form (Paget-von Schrotter syndrome) occurs in young adults due to underlying chronic venous compressive abnormality caused by musculoskeletal structures in the costoclavicular space
  • Axillosubclavian vein most common location because it is relatively fixed in the thoracic outlet, therefore it is exposed to repeated trauma with arm movement
  • Etiology: central venous catheter (CVC), permanent cardiac pacer, mediastinal tumors, radiation, surgery, hypercoagulable states
  • Increasingly common. 8% of all DVTs
  • Complications: pulmonary embolism, SVC syndrome, postthrombotic venous insufficiency, loss of vascular access
  • The most powerful independent predictor of UEDVT = presence of CVC (increases the risk by 7 folds)
  • Other risk factors in patients without CVC: young age, lean body weight and inpatient status
  • US is the imaging modality of choice
  • US shows lack of compressibility, absence of color flow signal and augmentation, visualization of thrombus
  • Radiography may show cervical rib, fractured rib or clavicle


1. Joffe HV, Kucher N, Tapson VF, et al. Upper-extremity deep vein thrombosis: a prospective registry of 592 patients. Circulation 2004;110:1605-1611.

2. Greben C and Charles HW. Deep vein thrombosis, upper extremity. In eMedicine, updated Jul 28, 2009.

August 24, 2010

Lunate Dislocation

Lateral radiograph of the wrist shows a volar dislocation of the lunate (arrow) relative to the position of the radius (R) and capitate (C).

Facts: Lunate Dislocation
  • "Spilled teacup" sign (as seen on this lateral radiograph)
  • Final stage of perilunate injuries
  • Most severe form of perilunate injuries, highest degree of instability
  • On lateral view of the wrist, the line drawn along the axis of distal radius, lunate and capitate should be almost straight. In this case, the line is disrupted because lunate is dislocated volarly.
Kaewlai R, Avery LL, Asrani AV, et al. Multidetector CT of carpal injuries: anatomy, fractures, and fracture-dislocations. Radiographics 2008;28:1771-1784.

August 21, 2010

Acute Cholecystitis

Coronal CT images show dilated gallbladder (GB), thickened wall, mucosal hyperenhancement with an obstructing cystic duct stone (arrow) in a 57-year-old man who presents with acute abdominal pain.

Facts: Acute Cholecystitis
  • It is a difficult clinical diagnosis. Potential clinical signs that can be helpful to rule in the diagnosis are 1) Murphy sign (positive likelihood ratio = 2.8), 2) RUQ tenderness
  • Diagnosis requires a combination of clinical, lab and imaging tests.
  • No single clinical finding or lab test has sufficient weight to establish or exclude cholecystitis without further testing (eg, imaging)
  • Evaluation of patients with abdominal pain suggestive of cholecystitis continues to rely heavily on the clinical gestalt and diagnostic imaging
Facts: Acute Cholecystitis CT Findings
  • Gallbladder distention*
  • Wall thickening*
  • Mucosal hyperenhancement
  • Pericholecystic fat stranding or fluid
  • Gallstones (with sufficient attenuation difference from bile to be visualized)
  • CT rim sign (increased enhancement of hepatic parenchyma in the gallbladder fossa)
  • CT is less accurate than ultrasound in establishing or excluding cholecystitis. However, CT is better to show complications of cholecystitis such as emphysema, gangrene, perforation, abscess or hemorrhage.
* In one study (ref #3), distended gallbladder was considered when size greater than 5 x 8 cm, and thickened wall when greater than 4 mm in noncollapsed gallbladder (short axis greater than 2 cm).

1. Trowbridge RL, Rutkowski NK, Shojania KG. Does this patient have acute cholecystitis? JAMA 2003;289:80-86.
2. Shakespear JS, Shaaban AM, Rezvani M. CT findings of acute cholecystitis and its complications. AJR 2010;194:1523-1529.
3. Fidler J, Paulson EK, Layfield L. CT evaluation of acute cholecystitis: findings and usefulness in diagnosis. AJR 1996;166:1085-1088.

August 18, 2010

Ovarian Hyperstimulation Syndrome

Ultrasound images show enlarged ovaries with multiple cysts in a woman who had received assisted reproduction procedure. Ascites is also present but not shown on these images.

Facts: Ovarian Hyperstimulation Syndrome (OHSS)
  • Complication related to exogenous administration of human chorionic gonadotropin (HCG) for assisted reproduction
  • Believed to be due to increased capillary permeability, resulting in fluid shift from intravascular to extravascular compartments
  • Broad clinical spectrum, ranging from mild, moderate to severe, but can be life threatening
  • Common in mid- to late-luteal phase
  • Early signs: abdominal heaviness, tension and pain (due to bilateral ovarian enlargement with multiple cysts)
  • Risk factors: young patient (less than 30 years old), underlying polycystic ovaries, high number of follicles and estradiol levels at the time of HCG injection, protocols that utilize GnRH
  • Golan classification describes 5 grades of OHSS based on ovarian size, symptoms (abdominal distention, nausea, vomiting, dyspnea), signs (ascites, pleural effusion, hemoconcentration, hypovolemia, oliguria).
  • Ultrasound most appropriate imaging to confirm clinical suspicion
  • Enlarged ovaries with several cysts
  • Ascites, pleural effusion
  • Necklace sign (string of ovarian follicles close to the surface of the ovary) may indicate an increased risk of developing this syndrome
1. Gianaroli L, Ferraretti AP, Fiorentino A. The ovarian hyperstimulation syndrome. Reproductive Med Rev 1996;5:169-184.
2. Golan A, Ron-El R, Herman A, et al. Ovarian hyperstimulation syndrome: an update review. Obstet Gyncol Surv 1989;44:430-440.

August 15, 2010

Pulmonic Valvular Stenosis

Chest radiograph reveals dilatation of the main pulmonary artery with relatively normal-sized right and left pulmonary arteries. The aorta is left sided.

Facts: Pulmonary Valvular Stenosis
  • Common congenital heart defects, approximately 10% of all cases
  • Classified as subvalvular, valvular and supravalvular stenosis (based on level of obstruction) and as mild, moderate and severe (based on pressure gradient across stenosis). It can occur in branch pulmonary arteries as well
  • May occur in isolation (as in our case) or be associated with other complex congenital heart defects
  • In severe cases, physical and ECG findings of right axis deviation, right ventricular hypertrophy would be apparent
Imaging Findings
  • Cardiac ultrasound: obstruction at right ventricular outflow tract (RVOT), pulmonary valve (PV), main pulmonary artery, right and left pulmonary arteries, abnormal pulmonary valve annulus, abnormal pressure gradients across RVOT, PV and pulmonary arteries
  • Radiography: enlargement of the main pulmonary artery, right ventricular hypertrophy. Radiographic differential diagnoses are pulmonary hypertension, idiopathic dilatation of the pulmonary trunk
Our case - pulmonary valvular stenosis in a young woman who had the diagnosis since birth and had undergone valvulotomy.

1. Heiden K. Congenital heart defects, simplified. 2009
2. Castaner E, Gallardo X, Rimola F, et al. Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview. Radiographics 2006;26:349-371.

August 12, 2010

Giant Bulla Vs. Pneumothorax

Chest radiograph shows a large lucent area in the right upper lobe with compression of the remaining lung parenchyma. In a patient with acute symptoms and no previous radiograph for comparison, this may raise a diagnostic dilemma whether it represents localized pneumothorax or just a giant bulla.
Coronal-reformatted CT image confirms the absence of pneumothorax in this case. Several bullae are clearly visualized.

Facts: Bulla, Giant Bulla
  • Air-filled space in the lung parenchyma due to destruction of alveolar tissue, distal to terminal bronchiole
  • Larger than 2 cm in distended state
  • Bullae + emphysema = bullous emphysema (can be congenital or complication of COPD)
  • Giant bulla = bulla larger than one third of the hemithorax size and compression of adjacent lung parenchyma
Distinguish Giant Bulla from Pneumothorax
  • Important for treatment plan (bulla - no tube thoracostomy; pneumothorax - may need tube thoracostomy if large or symptomatic)
  • Differentiation can be difficult on conventional radiography; they can coexist
  • Helpful signs for pneumothorax: visible visceral pleural line
  • Expiratory chest radiograph may help delineating a visceral pleural line of pneumothorax
  • CT scan is the most accurate mean to differentiate the two diagnoses
  • "Double wall" sign described in cases with ruptured bulla causing pneumothorax (air outlining both sides of the bulla wall parallel to the chest wall)
Lesson: Don't be shy to ask for a CT scan in this scenario. It is better to "do right" than "be right". The treatment is very different, and remember that the two diagnoses can coexist.

Waseem M, Jones J, Brutus S, et al. Giant bulla mimicking pneumothorax. J Emerg Med 2005;29:155-158.

August 9, 2010

Intervertebral Disc Calcification

Sagittal-reformatted CT image of the lower thoracic spine shows a central disc calcification. Several levels of endplate changes are noted as well.

Commonly Found in Elderly
  • Found in 80% of elderly cadavers in a large study
  • Mostly located in the periphery of the disc (annulus fibrosus), followed by central and diffuse
  • Mostly in lower thoracic spine, followed by midthoracic and lumbar spine
  • Increase in prevalence with increasing age
Differential Diagnosis
  • Degenerative disc
  • Postoperative, post-traumatic
  • Arthritis: ankylosing spondylitis, CPPD, gout
  • Metabolic disease: ochronosis, hemochromatosis, hypervitaminosis D

Chanchairujira K, Chung CB, Kim JY, et al. Intervertebral disk calcification of the spine in an elderly population: radiographic prevalence, location, and distribution and correlation with spinal degeneration. Radiology 2004;230:499-503.

August 6, 2010

Thyroglossal Duct Cyst

Sagittal CT image of the neck shows a cystic mass (arrow) in the midline anterior to the hyoid bone (arrowhead) in a young male patient.

  • Cystic lesion in the midline of the anterior neck near the hyoid bone
  • Common, accounted for 70% of all congenital neck mass
  • Usually is mobile, midline or slightly off midline
  • Can be anywhere along the route from foramen cecum to the lower neck (a path the thyroid gland descends to reach the anterior trachea). But most are below the level of hyoid bone
  • Treatment involves removal of the entire duct, part of the hyoid bone and tissue at the base of tongue
Differential Diagnosis
  • Dermoid cyst
  • Liquefied submental or anterior cervical lymph node
Seibert J, James C. Pediatric Radiology Casebase, 1997.

August 3, 2010


Axial CT image shows a small well-defined hyperdense lesion (arrow) in the gray-white matter junction of the left posterior parietal lobe without evidence of mass effect or surrounding edema.
Axial T2W MR image shows the lesion predominantly high signal intensity with a complete ring of dark T2 signal, suggesting the presence of hemosiderin.

Facts: Cavernoma
  • Low-flow vascular anomaly of the brain
  • Endothelium-lined blood cavities without muscular or adventitial layers. No brain tissues present between these blood cavities
  • May be sporadic, related to prior radiation, or hereditary
  • Patients commonly present with seizures due to internal bleeding
  • Annual bleeding rate between 0.25 to 0.7% per year
  • On follow up, most cavernomas increase in size due to osmotic changes
  • 80% are supratentorium, and size between 1-2 cm
  • Appearance depends on amount of internal thrombosis, hemorrhage and calcification
  • MRI is the modality of choice because it can show various stages of bleeding in the lesion, which is characteristic for cavernoma
  • If presents with acute hemorrhage, CT appearance will be similar to intracerebral hemorrhage of other causes. MRI in acute phase may provide a clue to the diagnosis of cavernoma if it shows various stages of bleeding in particular the presence of hemosiderin
  • If presents incidentally, cavernoma appears as a hyperdense mass without causing mass effect on CT. If calcified, it will be only partially calcified. On MRI, it shows a complete ring of dark T2 signal due to the presence of hemosiderin (this effect is best seen on GRE T2* sequence)

Kuker W and Forsting M. Cavernomas and Capillary Telangiectasias. In: Baert AL, Knauth M, Sartor K. Intracranial Vascular Malformations and Aneurysms, 2nd revised edition, 2008