September 30, 2009

RiTradiology Celebrating 22,222 visitors

"Shadow of Dharma" by Thanwa Sudsang, MD

We are celebrating our 22,222 visitors on September 28, 2009. Thanks for visiting the site and please feel free to comment, request, submit a case for posting or a photo for the illumination.

Achilles Tendon Rupture

Lateral view of the ankle shows an avulsed bone fragment (arrow) from the donor site (arrowhead) at the attachment of the Achilles tendon.

  • Achilles tendon is the thickest and strongest tendon in the human body
  • It is also the most commonly ruptured tendon
  • Most frequent mechanism is a sudden, forceful contraction of gastrocnemius
  • Most common at zone of avascularity 2-6 cm above the calcaneal insertion
  • 30-50 years old, recreational athletes (usually playing basketball, racket sports, soccer or softball)
  • Sudden pain after a pushing-off movement, audible pop, immediate weakness, palpable defect. Positive Thompson test
  • Clinical confounders: tear of other tendons (plantaris, flexor, peroneal), soft tissue edema limiting physical exam by palpation
  • In young, active patients, full-thickness tear is frequently treated by surgery. Nonsurgical options are considered in partial-thickness tear, sedentary, and high surgicalrisk patients
Role of Imaging
  • To assess if there is an avulsed bone fragment (radiography)
  • To differentiate between partial and full thickness tear (ultrasound, MRI)
  • Findings of full-thickness tear (both US and MRI): non visualization of tendon, tendon retraction, fat herniation into the tendon gap.
  • Additional findings seen on US of full-thickness tear: posterior acoustic shadowing due to refraction of sound beam at the frayed tendon, visualization of plantaris tendon
Our case: ruptured Achilles tendon associated with calcific tendinopathy

1. Hartgerink P, et al. Full- versus partial-thickness Achilles tendon tears: sonographic accuracy and characterization in 26 cases with surgical correlation. Radiology 2001; 200:406-412.
2. Skinner HB. Current diagnosis and treatment in orthopedics. McGraw-Hill Professional, 4th edition, 2006.

September 27, 2009

Ludwig Angina

Fig 1: Axial contrast-enhanced CT image shows extensive subcutaneous inflammatory change, fluid (yellow stars) in the left submandibular space. There are enlarged and inflamed left sternocleidomastoid (arrow) and left mylohyoid muscles (green star). Several drains (arrowheads) are present. The patient is intubated.
Fig 2: Coronal-reformatted CT image shows similar findings in the left submandibular region (arrow and yellow stars). There are several fluid collection in the superior mediastinum (red stars).

  • Ludwig is a name of a German surgeon who first described this condition in 1836; angina in Latin means "to strangle"
  • Infection of the submandibular space usually preceded by odontogenic infection (particularly when the 2nd or third molar involved). The infection extends inferiorly to mandibular insertion of the mylohyoid muscle, then spreads into the submandibular space and then along neck fascial planes.
  • Common cause: mixed aerobic and anaerobic bacteria (normal oral flora)
  • Male, 20-40 years old
  • Preceding odontogenic infection, peritonsillar abscess, mandible fracture or other facial trauma
  • Currently, mortality is about 10%
How to Diagnose
Suggested diagnostic criteria: cellulitis (not need to be abscess), submandibular space (bilateral or unilateral), gangrene with foul serosanguinous fluid on incision, fascia-muscle-connective tissue involvement and sparing of glands, direct spread rather than by lymphatics

How Infection Gets to Other Spaces
Submandibular space connects with other spaces, including parapharyngeal, retropharyngeal spaces. These spaces also connect with other deep spaces of the neck. These are also interconnected with the mediastinum (therefore Ludwig angina can cause acute mediastinitis, empyema and pericarditis).

Our case: Ludwig angina causing acute mediastinitis and empyema.

1. Rosen EJ, Bailey BJ. Deep neck spaces and infections. University of Texas Medical Branch at Galveston Website.
2. Marcus BJ, et al. A case of Ludwig angina. Am J Forensic Med Pathol 2008;23:255-259.

September 24, 2009

Splenic Artery Aneurysm

Figures 1&2: Axial contrast-enhanced CT images (2nd image is a maximum-intensity projection image) show a 2-cm saccular aneurysm (arrows) of the mid splenic artery in a 38-year-old woman with idiopathic hepatic cirrhosis, portal hypertension and splenomegaly. CA = celiac artery

Facts About Splenic Artery Aneurysm
  • Most common visceral artery aneurysm
  • Incidence up to 7% in autopsy series, nearly 1% on abdominal angiographic series
  • Most are saccular
  • Most are in mid or distal splenic artery
  • Women > men
  1. Degenerative from underlying medial fibrodysplasia (atherosclerosis not considered to be the primary etiology)
  2. Inflammatory: almost always related to pancreatitis and pseudocysts
  3. Posttraumatic
  4. Pregnancy related: high association with mortality for mother and fetus with ruptured aneurysms
Most surgical literature recommends repair if
  • Larger than 2 cm
  • Enlarging on follow ups
  • Pregnant patients or in women of childbearing age who might become pregnant
Open repair or endovascular therapy

Kandarpa K. Peripheral Vascular Intervention. Lippincott Williams & Wilkins, 1st edition (October 1, 2007).

September 21, 2009

Rectus Sheath Hematoma Following PEG Placement

Axial CT image of the abdomen shows a gastrostomy tube balloon (arrow) in the stomach. There is a hyperdense mass in the left rectus sheath (star).

Enteral Nutrition Options
  • Nasogastric tube: poorly tolerated by patients, difficult to maintain and increased risk of aspiration
  • Nasojejunal tube: better than NG tube but easily blocked
  • Gastrostomy tube -- can be placed surgically, radiologically or endoscopically
  • Jejunostomy tube: alternative to gastrostomy tube in patients with aspiration
Percutaneous Endoscopic Gastrostomy (PEG)
  • Placement of gastrostomy tube using the percutaneous approach and guided by concurrent endoscopy.
  • "Pull technique" most commonly used today
  • Patient is on conscious sedation
  • Endoscopy is used to find the optimal puncture site, using "finger pressure"

Indications for PEG
  • Need for enteral nutrition in patients unable to swallow
  • Provision of supplemental feeding or bile replacement
  • Gastric decompression in cases of chronic intestinal obstruction
Complications of PEG
  • Overall, 8% - 30%. Serious complications at approximately 1% - 4%
  • Pneumoperitoneum is frequently observed after PEG placement and is not regarded as a complication
  • Most frequent complication = local wound infection
Our case - left rectus sheath hematoma following PEG placement.

1. Loser C, Aschi G, Hebuterne X, et al. ESPEN guidelines on artificial enteral nutrition - percutaneous endoscopic gastrostomy (PEG). Clin Nutrition 2005;24:848-861.
2. Ponsky JL. Percutaneous endoscopic gastrostomy. J Gastroenterol Surg 2004;901-904.

September 18, 2009

Acoustic Noise in MRI

Acoustic (Sound) Noise in MRI

  • One of the most disturbing obstacles for patients receiving an MRI particularly children and psychiatric patients
  • Interferes with communication between MRI technologists and patients
  • Interferes with functional MRI studies by producing unwanted stimulus. Noise may introduce changes in oxygenation in cortex and blood capillaries that may in turn affect signal receiving during fMRI.
  • They were anecdotal reports of temporary hearing loss related to MRI, but these have never been proven.
  • Depends on pulse sequence, types of scanner (coil structures and coil supports)
  • Average relative noise = 94-107 dB (in MRI bore) and 87-98 dB (in MR scanning room)
  • Noise from gradient recalled echo (GRE) sequences typically is louder than spin echo (SE) and echo planar imaging (EPI).
  • Main source: Lorentz forces acting on gradient coils and pulsing particularly two gradients along x- (frequency encode) and y- (phase encode) axes
  • Other sources: vibrations of conducting cryostat inner bore of MR machine due to eddy current, vibrations of radiofrequency body coil, etc (including several "unknown" pathways)

Image from

1. Cho ZH, Park SH, Kim JH, et al. Analysis of acoustic noise in MRI. Magn Reson Imaging 1997;15:815-822.
2. Edelstein WA, Hedeen RA, Mallozzi RP, et al. Making MRI quieter. Magn Reson Imaging 2002; 20:155-163.

September 15, 2009

Bicuspid Aortic Valve

Fig. 1: Chest radiograph of a 44-year-old man shows prominence of the right cardiac contour, probably due to enlarged ascending aorta and aortic root. The overall heart size is slightly increased.
Fig. 2: Axial CT image at the level of the aortic valve shows a bicuspid valve (arrows) with calcifications of the valve leaflets (arrowheads).


  • Most common congenital cardiac malformation, 1%-2% of population
  • Majority of cases develop complications requiring treatment
  • Abnormal cusp formation during valvulogenesis
  • May be a part of a continuum: unicuspid valve (severe form), bicuspid valve (moderate form), tricuspid valve (normal) and quadricuspid form
  • May be genetic. Not clear if inheritable but studies had shown that this condition could be transmitted in autosomal dominance form, with male to female ratio of 4:1.
  • Most common = aortic stenosis
  • Bicuspid aortic valve very common among patients age 15-65 years with significant aortic stenosis
  • The fewer the number of cusps, the greater is the chance that the valve is stenotic from birth
  • Other complications: aortic insufficiency, endocarditis, aortic dilatation/aneurysm, dissection
  • It is believed that changes of the aorta (dilation, aneurysm) are not secondary to valvular dysfunction, but rather a manifestation of the disease itself

Surgery if: Severe aortic insufficiency/stenosis, dilated aorta, increased left ventricular size, decreased left ventricular function

Our case: bicuspid aortic valve with aortic stenosis.

Fedak PW, Verma S, David TE, et al. Clinical and pathophysiological implications of a bicuspid aortic valve. Circulation 2002;106:900.

September 12, 2009

Sacral Insufficiency Fracture

Figure 1: Axial CT image shows diffuse osteopenia, bilateral sacral alar fractures (arrowheads) and patchy scleroses in the sacral ala in an elderly women presenting with low back and pelvic pain without trauma.
Figure 2: Axial T2 MR image with fat suppression shows, in addition to CT, high T2 signal intensity in the sacrum (red arrows). Areas of sclerosis (yellow arrows) are seen as low T2 signal intensity.

Facts: Sacral Insufficiency Fracture
  • Fractures of the sacral ala related to axial stress on the underlying deficient elastic resistant sacrum. Frequently bilateral, involving sacral ala parallel to the sacroiliac joints
  • Exact incidence unknown but one prospective study shows a frequency of 1.8% in women aged over 55 years old with low back pain. It is more common than generally thought, and remains overlooked as a cause of pain and disability in the elderly
  • Risk factors: elderly women, osteoporosis, steroid-induced osteopenia, radiation therapy
  • High index of clinical suspicion is key. Suspect SIF in patients with sudden onset of low back and pelvic pain without trauma who are at risk of osteopenia.
  • Serum alkaline phosphatase (ALP) are often slightly elevated.
  • Best imaging tool = MRI.
  • MRI can show low T1 and high T2 signal in the sacral ala corresponding to bone marrow edema, and also fracture lines.
  • Alternatively, bone scintigraphy requires a minimum time lapse of 48-72 hours from symptom onset to show SIF. Classic "H" pattern require bilateral involvement
  • Radiographs are usually inadequate to demonstrate SIF, especially in acute setting and before the development of healing. In healing phase, sclerotic lines may be seen in the sacral alae
  • CT findings can be subtle. It can show sclerotic healing lines, and/or acute fracture lines - but can be quite subtle.
  • Major differentials on imaging = malignancy and osteomyelitis
Tsiridis E, Upadhyay N, Giannoudis PV. Sacral insufficiency fractures: current concepts of management. Osteoporos Int 2006;17:1716-1725.

September 9, 2009

The Luftsichel Sign

A PA chest radiograph shows low left lung volume, haziness of the left lung with obliteration of the left heart border, a Luftsichel sign (arrowheads).
A lateral chest radiograph shows an anteriorly displaced left major fissure (arrows). The collapsed left upper lobe is up against the anterior chest wall.

Facts: Luftsichel sign
  • Seen on PA chest radiograph of patients with left upper lobe collapse
  • Paraaortic crescent of air with sharp margin extending anywhere from left apex to left superior pulmonary vein
  • Luft = air; sichel = sickle [German]
  • Caused by expansion of superior segment of left lower lobe due to left upper lobe collapse.
  • In adults, it is an important clue to diagnose collapse that may be due to an obstructing endobronchial neoplasm.

Signs of Left Upper Lobe Collapse
  • On PA view: Low left lung volume (elevated diaphragm), haziness of the left lung with obliteration of left heart border, elevated left hilum, near-horizontal course of the left main bronchus, Luftsichel sign
  • On lateral view: Anteriorly displaced major fissure that parallels the anterior chest wall
Blankenbaker DG. The Luftsichel sign. Radiology 1998;208:319-320.

September 6, 2009

Sinistral (Left-sided) Portal Hypertension

Fig. 1: Axial CT image in a 44-year-old woman shows multiple dilated venous collaterals (varices) along the stomach (arrows).
Fig. 2: Axial CT image of the same patient shows a large pancreatic pseudocyst (stars) with absence of the splenic vein, indicating splenic vein thrombosis from chronic pancreatitis.

Sinistral (Left-sided) Portal Hypertension
  • Localized form of extrahepatic portal hypertension developed after splenic vein thrombosis/obstruction
  • Formation of varices, with potential for massive upper GI bleeding
  • Most common cause = chronic pancreatitis
  • Incidence: 7% of patients with chronic pancreatitis
  • Potentially curable by splenectomy
  • Suspected in patients with bleeding esophageal varices, splenomegaly and normal liver function
Splenic Vein Thrombosis/Obstruction as a Cause of Sinistral Portal Hypertension
  • In many patients, splenic vein obstruction is silent and undetected
  • Likely related to many factors: compression of the veins by chronic inflammation (i.e. pseudocyst), stasis, intimal injury related to recurrent pancreatitis, systemic hypercoagulable state
  • Leads to obstruction of splenic venous outflow. Venous blood from spleen returns to the heart via low-pressure collaterals (short gastric/gastroepiploic veins). This can be seen as gastric varices, and in some cases - esophageal varices.
1. Loftus JP, Nagorney DM, Ilstrup D, Kunselman AR. Sinistral portal hypertension splenectomy or expectant management. Ann Surg 1993;217:35-40.
2. Sakorafas GH, Sarr MG, Farley DR, Farnell MB. The significance of sinistral portal hypertension complicating chronic pancreatitis. Am Surgeon 2000;179:129-133.

September 3, 2009

Calcified Choroid Plexus Cysts

Axial CT image of the brain shows bilateral choroid plexus cysts in the atria of lateral ventricles with rim and internal calcifications (yellow arrow). Note physiologic calcifications of the habenula (short blue arrow) and pineal gland (long blue arrow).

Facts: Choroid Plexus Cysts
  • Nonneoplastic epithelial-lined cysts of choroid plexus
  • Most common neuroepithelial cysts in the CNS (50% of autopsy cases)
  • Most are bilateral and located in atria of lateral ventricles
  • Can be entirely cystic, nodular or partially cystic
  • Iso to slightly hyperattenuated on unenhanced CT (compared with CSF)
  • Common peripheral calcification
  • On MRI, cyst appears hyperintense on T2-weighted images, do not completely suppressed on FLAIR images and remain hyperintense to CSF, may show restricted diffusion on DWI
  • Differential diagnosis: ependymal cyst, villous hyperplasia

Osborn AG, Preece MT. Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology 2006;239:650-664.