March 30, 2009

Intracranial Aneurysms: Coil Embolization

Fig.1 & 2: Angiographic image of the left internal caroid artery injection shows an aneurysm of the left supraclinoid internal carotid artery. Fig.1 without subtraction, Fig.2 with.
Fig.3: Angiographic image after coil embolization (performed because the patient had SAH) reveals a coil within the aneursym.

Coil Embolization Complications

  • Complicaton rate 8.6% to 18.6% (median 10.6%), lower than surgical clipping
  • Common complications: thrombo-embolic events, perforation of aneurysm, parent artery obstruction, collapsed coil, coil malposition, and coil migration
Coil Embolization versus Aneurysm Clipping
  • Less risks of death
  • Higher rate of rebleeding (2.4% versus 1%) - why*
  • Advantages vary depending on location of aneurysm, but coil embolization is beneficial for all sites
*Percentage of complete aneurysm occlusion after coil embolization is lower than with surgical clipping
* Recurrence = refilling of thee neck, sac, dome of a successfully treated aneurysm

What to Choose?
  • Not all aneurysms required coil embolization. This depends on size, anatomy and location of aneurysms.
  • People at increased risk for craniotomy (>65 years, poor clinical status, comorbid conditions)
  • Suitability depends on size, anatomy, location of aneurysms (in ophthalmic artery or basilar tip artery)
  • Better perform craniotomy if
  • >10 mm size
  • > 4mm neck

Ontario Heath Technology Advisory Committee. Coil Embolization for intracrinal aneurysms.

March 27, 2009

Breast Hematoma

Fig. 1&2: Ultrasound of the right breast of a 79-year-old woman with a lump shows a mass with a fluid-fluid level (between arrows). The more dependent 'debris' appears to be more echogenic than the non-dependent fluid. There is no color flow within the mass.
Fig. 3: CT scan without IV contrast showed a large mass, again with a fluid-fluid level. The denser portion of the mass measured 60 HU, consistent with blood clot. The scan also revealed a markedly enlarged left atrium. The patient is on anticoagulant therapy for chronic atrial fibrillation.

  • Common causes: post procedure (biopsy, surgery), direct trauma, coagulopathy
  • Breast hematoma occurs in approximately 2% - 10% after breast surgery
  • Risk factors: use of some medications (aspirin, NSAIDs, anticogulants)
US Findings:
  • Depends on stage of blood product
  • Clotted blood appears echogenic, lysed blood (serum) appears cystic.
  • No internal flow

Our case - follow up ultrasound was performed and the mass has evolved into a lysed hematoma and then disappeared. Diagnosis was breast hematoma related to anticoagulant use.

Vitug AF, Newman LA. Complications in breast surgery. Surg Clin N Am 2007;87:431-451.

March 24, 2009

FDG-PET and Solitary Pulmonary Nodule Assessment (2)

Fig. 1: Axial CT image shows an ill-defined 1 cm nodule in the left upper lobe with internal cavity (arrow).
Fig. 2: Axial FDG-PET image at the same level as on CT shows no uptake of the nodule. Wedge resection of the nodule reveals bronchioloalveolar carcinoma.

False negative FDG-PET for lung malignancy

  • Bronchioloalveolar carcinoma
  • Carcinoid tumor
  • Mucinous tumors
Reasons for false negativity of these tumors may be:
  • Less number of cells in tumor (low cellarity relative to tumor volume)
  • Better degree of differentiation (well-differentiated), not much nuclear atypia or less mitotic figures
  • Lower metabolic rate
  • Less peritumoral inflammation
  • Small tumor size
How to Deal?
Goes by CT appearance and clinical scenario. If there is no characteristics of benignity of the nodule, at minimum - do a closed follow up with CT.

Gilman MD, Aquino SL. State-of-the-art FDG-PET imaging of lung cancer. Semin Roentgenol 2005;40:144.

March 21, 2009


Fig.1&2: Cross-table lateral radiograph (1) and sagittal-reformatted CT image (2) of the knee show a fat-blood interface (arrow) in the suprapatellar bursa of a 57-year-old woman who was a pedestrian hit by a car. Yellow asterisk = fat in the bursa, red asterisk = blood.


  • Mixture of blood and fat in a joint cavity following trauma
  • Fat from the marrow space enters the joint through intra-articular fracture
  • Fat is less dense than blood; therefore it layers above blood.
  • On x-ray, fat is less dense than blood; therefore it can be seen as different density using radiography and CT
  • Horizontal beam of x-ray needs to be parallel to the fat-blood interface, to be able to demonstrate the interface.
  • Described in intra-articular fractures of the knee, shoulder, hip and elbow. However, it is not seen in all cases of intra-articular fracture. On the other hand, it is helpful for the diagnosis of an occult fracture.
Arger PH, Oberkircher PE, Miller WT. Lipohemarthrosis. AJR 1974;121:97-100.

March 19, 2009

Drug-Induced Eosinophilic Pneumonia

Fig.1: Chest radiograph of a 49-year-old woman, presenting with low-grade fever and cough for a month, shows patchy airspace opacities in both upper lobes.
Fig2&3: Axial CT images show asymmetric patchy consolidations and groundglass opacities mainly in the periphery of the upper lobes and superior segments of the lower lobes.

Differential Diagnosis of Subacute Bilateral Upper Lobe Airspace Opacities

  • Cryptogenic organizing pneumonia (COP)
  • Churg-Strauss syndrome (vasculitis)
  • Pulmonary infarction
Eosinophilic Lung Disease
  • A group of disorders characterized by 1) abnormal lung opacities with peripheral eosinophilia, 2) tissue eosinophilia confirmed at either open or transbronchial lung biopsy, or 3) increased eosinophil in bronchoalveolar lavage (BAL) fluid
  • Known causes: asthma, infection (coccidiodomycosis, PCP, mycobacteria), tumor (NSCLC, lymphoma, lymphocytic leukemia), collagen vascular disease (RA, Wegener's, IPF, LCH) and drugs
Drugs Associated with Eosinophilic Lung Disease
  • Amiodarone,
  • Methotrexate,
  • Nitrofurantoin,
  • Phenytoin,
  • B-blockers,
  • Iodinated contrast media,
  • ACE inhibitor
Pattern of Abnormalities in Chest CT
  • Bilateral, asymmetric, peripheral consolidations and groundglass opacities
  • Upper lung zone > random > lower
  • Ancillary findings: centrilobular nodules, reticulations, septal thickening

Our case is an eosinophilic pneumonia (confirmed by BAL fluid eosinophilia) associated with Minocycline, which had been improved after a short course of corticosteroid therapy.

1. Souza CA, et al. Drug-induced eosinophilic pneumonia: high-resolution CT findings in 14 patients. AJR 2006;186:368-373.

2. Jeong YJ, et al. Eosinophilic lung diseases: a clinical, radiologic, and pathologic overview. Radiographics 2007;27:617-637.

March 16, 2009

Epiploic Appendagitis

An axial CT image of a 43-year-old man with left lower quadrant pain shows an oval fatty mass (arrow) with surrounding fat stranding. There is fascial thickening (arrowheads).

Epiploic Appendagitis

  • Torsion of epiploic appendages results in vascular occlusion, leading to ischemia
  • Inflammation of appendages is self limited. Rarely, it may result in adhesion, bowel obstruction, peritonitis, or abscess
  • Common in 4th to 5th decades of life
  • Acute pain, most in left lower quadrant - easily mistaken for acute diverticulitis
CT Appearance
  • Anterior to colonic lumen, sigmoid colon > descending colon > cecum
  • Oval fatty mass surrounded by inflammation, 1.5cm and 3.5cm size
  • Central high-density focus represents venous thrombosis
  • Colonic wall thickening rare

Singh AK. CT appearance of acute appendagitis. AJR Am J Roentgenol 2004;183:1303-1307.

March 13, 2009

Intracranial Aneurysms

Fig.1: Unenhanced axial CT of the head of a patient without recent trauma shows diffuse, bilateral subarachnoid hemorrhage (arrowheads), left greater than right. There is blood in the cerebral sulci as well as in the CSF cisterns.
Fig.2: Axial CT with IV contrast (angiographic technique) shows a left supraclinoid internal carotid artery aneurysm (arrow), measuring 6-7 mm.

Intracranial Aneurysms

  • Dilatation or ballooning of intracranial blood vessel, small <12>25mm
  • Three types: fusiform, saccular and dissecting
  • Berry aneurysm is of a saccular type
  • Common at branch points of large arteries that form the circle of Willis
  • Anterior circulation (85% - 95%) > posterior circulation
  • Most aneurysms are small and asymptomatic. Large ones may cause mass effect to cranial nerves and brain.
  • Rupture usually results in subarachnoid hemorrhage (SAH) with high mortality of up to 50%
  • Overall rupture risk is 1.9% per year, higher in women, cigarette smokers, cocaine users, symptomatic aneurysms, >10mm, and located in posterior circulation
Ontario Health Technology Advisory Committee. Coil Embolization for Intracranial Aneurysms. January 2006.

March 10, 2009

Subependymal Giant Cell Astrocytoma

Fig 1&2: Axial and coronal MR images (contrast enhanced T1WI) show an enhancing mass in the left caudothalamic groove in a patient with known tuberous sclerosis. Given the size and enhancement on this initial scan, a concern of SGCA should be raised.

Subependymal giant cell astrocytoma (SGCA)

  • 1 in 10 individuals with TSC
  • Arises from subependymal nodules
  • Can result in ventricular obstruction
  • It is recommended by the National Tuberous Sclerosis Association that brain imaging obtainend at every 1-3 years in children, up to the age of 21 years, to detect giant cell astrocytoma

Imaging Appearances That May Suggest SGCA
  • Serial growth (best imaging predictor)
  • Hydrocephalus
  • Contrast enhancement
  • Size >1 cm
Goh S, Butler W, Thiele EA. Subependymal giant cell tumors in tuberous sclerosis complex. Neurology 2004;63:1457-1461.

March 7, 2009

Chronic Pulmonary Embolism

Fig. 1&2: Axial CT image shows a partial thrombus (stars) in the main and proximal left pulmonary artery that forms an obtuse angle with the vessel wall. There is enlarged pulmonary artery and bronchial collaterals (arrows).


  • Some pulmonary emboli do not resolve and form endothelialized fibrosis of pulmonary vascular bed, thought to be due to disturbance in thrombus resolution
  • Results: pulmonary HT, cor pulmonale, bronchial hypertrophy
  • Multiple episodes of PE
  • Younger age
  • Larger perfusion defect
  • Idiopathic cause of PE
CT signs
  • Complete thrombus with small vascular diameter
  • Partial crescent-shaped, eccentric thrombus
  • Calcified thrombus
  • Web, band
  • Pulmonary hypertension
  • Collaterals from bronchial arteries
  • Mosaic attenuation of the lungs
Castaner E, et al. CT diagnosis of chronic pulmonary thromboembolism. Radiographics 2009;29:31-50.

March 3, 2009

Commoditization of Radiology

In the latest issue of the Journal of the American College of Radiology (JACR), Giles Boland MD took on a hot topic of 'commoditization' of radiology specialty.

What is Commoditization?
  • The word 'commoditization' is actually derived from a noun 'commodity'. Commodity means "a raw material or primary argricultural product that can be bought and sold, such as copper or coffee" , according to an Apple's Dictionary.
  • According to Wikipedia: Commodity is "anything for which there is demand but that is supplied without qualitative differentiation across a market".
  • "A product that is the same no matter who produces it."
  • Examples: oil, rice, sugar, salt, ethanol, gold, silver
What If Radiology Is a Commodity...
  • No referring physicians care whether who interprets the examination.
  • There is no differentiation among different providers.
  • Price of radiology services are determined as a function of the market: fluctuating and universal, changing based on supply and demand.
  • Etc.
What Leads Radiology To Become a Commodity?
  • Electronic imaging network, PACS
  • Teleradiology
  • Individual radiologist
What Radiologists Can Do To Prevent It?
Well, you can't stop the pace of technology (electronic networking, PACS), and business (teleradiology), but you can do more as an individual radiologist:
  1. Be a part of clinical care team: active participation in an interdepartmental conference, active engagement in patient care (phone call or personal discussion)
  2. Build an effective relationship with referring physicians
  3. Guide technologists to obtain appropriate images of high quality
  4. Devise disease-specific imaging protocols
  5. Participate in an effort to reduce radiation dose
  6. Actively involve in reduction of unnecessary imaging and update imaging appropriateness criteria
  7. Educate younger, newcomer radiology residents, fellows, medical students on best imaging practice
  8. Be subspecialized, or at least having an area of expertise in one or two specific modalities or clinical specialties, to keep up with referring physicians.

Boland GWL. Teleradiology for auction: the radiologist commoditized and how to prevent it. JACR 2009 (DOI 10.1016/j.jacr.2008.10.006).