December 31, 2011

Calcification in Lung Nodule

A spot chest radiographic view of the left lower lung zone (with a nipple marker) shows a 1-cm nodule (arrow) in the lung base just medial to the nipple marker.

Non-contrast CT confirms the presence of a nodule in the left lower lobe (arrow) that contains a central calcification.

Lung Nodule Calcification
  • Up to 6% of lung cancer have calcification. Therefore, calcium in a nodule does not exclude possibility of lung cancer
  • Suspected malignant nodule if calcium is.... eccentric, amorphous or it involves only a small portion of the nodule
  • Benign: central (>10% of cross-sectional area of nodule), diffuse and laminated calcification
  • Nodules that are nonsolid or partly solid are more often malignant
Our case: benign nodule, likely a granuloma.

Hodler J, von Schulthess GK, Zollikofer ChL. Diseases of the Heart, Chest & Breast 2011-2014. Springer-Verlag Italia 2011.

December 21, 2011

Sternoclavicular Rheumatoid Arthritis

Axial CT images of the sternoclavicular joints show erosion, indistinct cortical margins of the joints, which are quite symmetric.

  • Sternoclavicular (SC) joint is diarthrodial articulation between axial and appendicular skeleton, which is subject to same disease process that occur in other joints (degenerative arthritis, rheumatoid arthritis, infection and subluxation. Degenerative arthritis is the most common).
  • Up to 30% of patients with rheumatoid arthritis have changes in SC joints (a part of polyarticular involvement) but radiographic findings are often unremarkable.
Imaging Finding
  • Synovitis
  • Bone marrow edema and enhancement of subcortical bone (after IV contrast)Er
  • Erosion and indistinct cortical margins
  • Think infection if: unilateral, history of IVDU and immunocompromised states
1. Restrepo CS, Martinez S, Lemos DF, et al. Imaging appearance of the sternum and sternoclavicular joints. Radiographics 2009; 29:839-859.
2. Berry DJ, Steinmann SP. Adult Reconstruction, 2007.

December 11, 2011

Scrotal Pyocele

Gray-scale and color Doppler US images of the testicle shows a complex fluid collection (stars) around the testicle and marked scrotal skin thickening. The epididymis is edematous with increased flow (image not shown).

Facts: Scrotal Pyocele
  • Also known as scrotal abscess
  • Can be superficial (from infected hair follicles, wound) or intrascrotal
  • Causes: epididymitis, TB, instrumentation, neurogenic bladder, chronic catheter indwelling, spread from intraabdominal infection (i.e., appendicitis)
  • Intrascrotal abscess requires surgical drainage
  • US is the modality of choice
  • Complex-appearing fluid around the testicle
  • Scrotal skin thickening with hyperemia
  • Evidence of causes such as epididymitis or others
  • Based on imaging, it is difficult to distinguish pyocele from hematocele
1. Siegel MJ. Pediatric Sonography, 2010.
2. Resnick MI, Novick AC. Urology Secrets, 3rd ed, 2003.

November 21, 2011

Renal Scarring

A longitudinal ultrasound image of the kidney shows a focal depression of the lower pole cortex (arrows) with focal parenchymal thinning and a caliceal stone (between calipers).

  • Renal scar is a common incidental finding during imaging of the GU tract
  • It can occur both with and without episodes of infundibular obstruction
  • Reflux is considered a major contributor in development of non-obstructive scarring, particularly in children with vesicoureteric reflux (VUR)
  • In adults, renal scarring is more associated with renal stone disease, either with stone or history of stone
  • Focal cortical thinning and depression of the cortex, overlying the pyramid on any imaging modalities (IVU, US, CT, MR)
  • Hyperechoic band is seen over the parenchymal thinning on US
  • Mimic = normal renal lobulation. Lobulation will span the pyramids with echogenic lobular junctions into renal columns
Newhouse JH, Amis, Jr, ES. The relationship between renal scarring and stone disease. AJR 1988; 151:1153-1156.

November 11, 2011

Parotid Mass

US and CT images of a solid mass in the right parotid gland of an 82-year-old woman who had a painless neck mass for a year.

Facts: Parotid Mass Workup
  • Long list of differential possibilities: neoplastic vs. non-neoplastic conditions
  • Most helpful test = fine needle aspiration biopsy (accuracy 85-90% in experienced cytologist's hands)
  • CT/MRI helpful for treatment planning to determine disease extent and whether facial nerve would need to be sacrificed during surgery
Differential Diagnosis
  • Can be limited by patient's demographic information: age and immune status
  • Facial nerve palsy implies malignancy and poor prognosis
  • Children: hemangioma, lymphangioma, first branchial cleft cyst, pleomorphic adenoma
  • AIDS: benign lymphoepithelial cysts, infection, lymphoma
  • Adults: pleomorphic adenoma (>80%), Warthin tumor, malignant tumor (mucoepidermoid, adenoid cystic carcinoma), metastasis, lymphoma
  • Other nonneoplastic parotid masses: reactive adenopathy, cystic lymphoid hyperplasia, sarcoidosis
Our case: Warthin tumor confirmed by biopsy

1. Steward M, Selesnick SH. Differential Diagnosis in Otolaryngology: Head and Neck Surgery
2. Castillo M. Neuroradiology Companion: methods, guidelines, and imaging fundamentals, 3rd ed, 2006

November 1, 2011

Unilateral Diaphragmatic Elevation

An AP chest radiograph shows elevation of the right hemidiaphragm.

Unilateral Diaphragmatic Elevation: Differentials
  • Lung/pleural disease: Pneumonectomy, lobectomy, pleurisy, subpulmonic effusion
  • Diaphragm disease: Phrenic nerve palsy / eventration
  • Abdominal disease: Hepatomegaly / hepatic mass / abdominal neoplasm / distended stomach

US and CT images demonstrate a very large cyst in the right lobe liver as a cause of elevated right hemidiaphragm.

October 21, 2011

AFP-Negative Hepatocellular Carcinoma

An US image of the liver shows a 2 cm solid nodule in a cirrhotic liver.

CT images of the liver in arterial and portovenous phases show arterial contrast enhancement with rapid washout of the nodule.

Facts: Serum AFP & Hepatocellular Carcinoma (HCC)
  • First detection of AFP in serum of HCC patients in 1970s
  • Currently, it is the only widely used serologic marker for diagnosing HCC. Additional useful markers in use are AFP-L3 and DCP
  • Normal range 10-20 ng/mL
  • AFP greater than 400 ng/mL generally considered a point of discriminating HCC from other chronic liver disease
  • Problem: about 60% of patients with HCC have AFP below 200, up to 20% have normal AFP (AFP-negative HCC; AFP below 20)
Clinical Features of AFP-negative HCC
  • Less likely to be hepatitis B positive
  • Tend to have a lower level of ratio of serum glutamic oxaloacetic transaminase (AST)/pyruvic transaminase (ALT)

1. Law WY. Hepatocellular Carcinoma, 2007.
2. Nomura F, Ohnishi K, Tanabe Y. Clinical features and prognosis of hepatocellular carcinoma with reference to serum alpha-fetoprotein levels. Analysis of 606 patients. Cancer 1989;64:1700-1707.

October 11, 2011

Infected Second Branchial Cleft Cyst

Axial CT image of the neck in a 2-year-old boy shows a cystic lesion in the right neck anterior to the sternocleidomastoid muscle, lateral to the carotid space. There is wall enhancement and nearby fascial thickening and subcutaneous fat stranding.

Facts: Branchial Cleft Cyst
  • Type II = most common (92-99% of all branchial cleft cysts)
  • Anywhere along anterior aspect of sternocleidomastoid muscle, lateral to carotid sheath to parapharyngeal space at the level of palatine tonsil
  • CT: fluid density unless infected or hemorrhagic
  • MRI: T1 hypointense, T2 hyperintense (unless infected or hemorrhagic)
  • Can be associated with fistula or sinus tract
Other Things To Consider: Necrotic lymph node/metastasis, dermoid, abscess, laryngocele, ectopic thymic cyst

What Surgeons Want To Know
  • Infection? May need surgery if at risk of septicemia or abscess
  • Mass effects? Compression of esophagus, airways
  • Neoplasm?
  • Treatment of infected branchial cleft cyst is different from simple abscess. In the former, I&D alone is not adequate but the entire cyst and its tract must be removed to prevent recurrence. Therefore, it is important that accurate diagnosis is made preoperatively.
Our case: infected second branchial cleft cyst

1. Bailey BJ, Calhoun KH. Atlas of Head & Neck Surgery-Otolaryngology, 2001.
2. Lin EC, Escott EJ, et al. Practical Differential Diagnosis for CT and MRI, 2008.

October 1, 2011

Intussusception Reduction

A "scout" radiograph before intussusception reduction procedure shows a soft tissue mass (arrows) in the right upper quadrant representing the intussusception. There is no free air.

Contrast enema for reduction shows the intussusception (arrows) in the right upper quadrant. It was successfully reduced.

  • Image-guided liquid or air reduction of intussusception is the treatment of choice
  • Contraindications for image-guided reduction = peritonitis, free intraperitoneal air due to perforation, in shock or sepsis
  • Choice between air, liquid, contrast enema reduction of intussusception depends on radiologist experience and local preference/practice. Most radiologists prefer to use air and it is now generally accepted as the technique of choice
  • Air pressure: between 80 and 120 mmHg
  • Contrast: bag positioned approximately between 3 ft and 6 ft above the patient
  • Reduction rate between 80% to 95%
Preparation for Reduction
  • Notify the referring physician and surgeon
  • Patient must be stable, well-hydrated and has no evidence of peritonitis
  • IV line in place
  • A large-bore needle at hand (if you use air reduction)
  • Perforation rates with air enema less than 1%
  • Recurrence 10% of cases

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.
2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

September 21, 2011

Intussusception: Ultrasound

A longitudinal US image shows a "pseudokidney" sign of intussusception (arrows). Arrowheads point to enlarged mesenteric lymph nodes within the intussusceptum.

A transverse US image shows a "target" sign with a hypoechoic ring of the intussuscepiens surrouning the central echogenic area of intussusceptum. Arrowheads point to enlarged nodes.

  • A segment of bowel (intussusceptum) prolapses into a more distal bowel segment (intussuscepiens)
  • Most frequently seen in the first two years of life but can be seen up to 4 years. If older child has intussusception, looks for a lead point such as polyp, Meckel diverticulum, lymphoma, duplication cyst.
  • Classic triad: colicky pain, vomiting and bloody (red currant jelly) stools (seen in less than 25% of cases)
  • X-ray is positive in only 50% of cases, and is not reliable in diagnosing this condition

Ultrasound Findings
  • Modality of choice to diagnose intussusception
  • "Target" sign = hypoechoic ring with an echogenic center on transverse US image
  • "Pseudokidney" sign = hypoechoic bowell wall extending along a hyperechoic mucosa
  • Helpful in searching for a lead point. US can provide a specific diagnosis in one-third of these cases.

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.
2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

September 11, 2011

Tension Pneumothorax

Chest radiograph shows a very large left pneumothorax (stars) causing mass effect to the mediastinum (shifting, arrows), deep costophrenic sulcus and collapsed left lung.

  • One-way valve effect causing continuous air collection within pleural space resulting in collapse of the lung on the affected side and compression of opposite lung
  • Poor lung compliance and increased airway pressure leads to ineffective gas exchange
  • Mass effect on mediastinal structures cause decreased venous return and decreased cardiac output
  • Symptoms and signs: chest pain, dyspnea, respiratory distress, tachypnea, dyspnea, cyanosis, elevated jugular venous pressure, absent breath sounds, tracheal deviation and hemodynamic compromise
  • This is a clinical diagnosis and confirmation with radiography is not recommended. Needle decompression should be immediately performed
  • Again, this is a clinical diagnosis. Yet imaging may be performed and shows large pneumothorax, mediastinal shifting, flat hemidiaphragm
Greenberg MI. Greenberg's Text-atlas of Emergency Medicine, 2005.

September 1, 2011

Fracture of the Lateral Process of Talus

AP view of the foot shows a small avulsion fracture (arrow) of the lateral process of the talus.

Facts: Lateral Process of Talus
  • Lateral process is a broad-based, wedge-shaped prominence of the lateral talar body that articulates with the fibula and posterior facet of talus
  • Anchor point for lateral talocalcaneal, anterior and posterior talofibular ligaments
Facts: Fracture of the Lateral Process of Talus
  • Axial loading with elements of dorsiflexion and eversion or external rotation
  • High incidence among snowboarders, sometimes called "snowboarder fracture"
  • Can be difficult to diagnose clinically, easily confused with ankle sprain
  • Pain localized anteroinferior to the distal end of fibula
  • Important to look specifically at this area in patients presenting with lateral ankle pain following trauma
  • Small, nondisplaced fracture can be overlooked. CT may be warranted if suspicion persists in a normal-looking x-ray series
  • Hawkins classified this fracture into 3 types: 1) large single fragment, 2) large comminuted fragment, 3) small, extra-articular fragment
Browner BD, Levine AM, Jupiter JB, et al. Skeletal Trauma: Basic Science, Management, and Reconstruction, 2009.

August 21, 2011

Ileal Diverticulitis

Axial CT image shows an ileal diverticulum (arrow) with surrounding inflammation (arrowheads). Thin arrow = normal appendix.
Sagittal CT image again confirms the presence of an inflamed ileal diverticulum. Note a normal cecum.

  • Two percents of population have small-bowel diverticula
  • These can be congenital or acquired.
  • Acquired diverticula are common in jejunum and terminal ileum. They are mucosal herniation along the mesenteric border.
  • About 6-10% of patients with small-bowel diverticula develop complications (-itis, hemorrhage, obstruction, intussusception)
  • CT can show inflammatory change around the diverticulum with mural thickening of the adjacent bowel loops. The appendix and cecum are normal.

Gourtsoyiannis NC. Radiologic Imaging of the Small Intestine, 2002.

August 11, 2011

Kaposi's Sarcoma

Axial CT image shows perihilar peribronchovascular thickening (arrows) and several small ill-defined nodules in the peribronchovascular distribution.
Axial CT image shows patchy groundglass opacities and consolidation in the right middle and lower lobes.

  • Multicentric neoplasm occuring in three distinct clinical settings: classic (middle-aged adults or elderly men with indolent course), endemic (native populations of equatorial Africans) and disseminated forms (AIDS and immunosuppressed recipients of organ transplants)
  • Associated with human herpesvirus type 8
  • Cutaneous manifestations usually precede visceral disease
  • Respiratory disease is a late manifestation of the disease, it can involve trachea, bronchial tree, pleura and lung parenchyma
  • Diagnosis of respiratory disease is often made presumptively based on clinical/imaging appearance and exclusion of other entities. Biopsy is most definitive.
  • Treatment of pulmonary disease almost always involves chemotherapy
Thoracic Imaging Findings
  • Two patterns: interstitial and nodular
  • Interstitial pattern -- septal lines, localized/focal consolidations, perihilar distribution, "flame-shaped" opacities
  • Nodular pattern -- ill-defined nodules of various sizes that may coalesce into areas of patchy consolidation
  • Up to 60% has pleural effusion
  • Up to 16% has hilar/mediastinal lymphadenopathy
Our case: Kaposi's sarcoma, biopsy-proven

Humes HD. Kelley's Essentials of Internal Medicine, 2001.
Parsons PE, Heffner JE. Pulmonary/reespiratory Therapy Secrets, 2002.

July 31, 2011


Lateral radiograph of the neck shows a very large, well-defined calcification with layered appearance overlying the inferior aspect of the mandible.

Axial CT image confirms the location of the stone in the left submandibular gland. Dilated submandibular duct is also present (not shown).

  • Stone disease (sialolithiasis) is the most common disease of the salivary gland; male more common than female; very rare in children
  • Submandibular gland is the most common location of stones in the salivary gland (80% of all)
  • Stone disease is a common cause of acute and chronic salivary gland infections
  • Stones consist of mainly calcium phosphate
  • 20% of submandibular stones, and 40% of parotid stones are non-opaque
  • Occlusal radiographs useful in showing radiopaque stones
  • Sialography is useful in patients suspected of having non-opaque stones but it is contraindicated in acute infection
  • CT and ultrasound can show stones with high accuracy
  • Gland may be diffusely or focally enlarged with a stone in the duct
  1. Siddiqui SJ. Sialolithiasis: an unusually large submandibular salivary stone. Br Dent J 2002;193:89-91.
  2. Yousem DM, et al. Major salivary gland imaging. Radiology 2000;216:19-29.

July 21, 2011

Nephrogenic Systemic Fibrosis Disappeared After Restrictive Use of Gadolinium?

According to a large (50 000+) retrospective cohort of patients who underwent contrast-enhanced MR examinations at a single academic institution pre- and post-adoption of strict gadolinium guidelines:-
  • No new cases of nephrogenic systemic fibrosis (NSF) were diagnosed
  • During the pre-guidelines adoption and transitional period, the incidence of NSF was 3 cases per 10,000 contrast-enhanced MRI
  • After the adoption of guidelines, the incidence was 0 per all examinations
The Guidelines for Imaging Adult Patients
  • Based on renal disease severity
  • eGFR 60 or greater - GBCA can be administered as indicated
  • eGFR 30-59 - weight-based dose of GBCA (0.2 mL/kg) can be administered with maximal dose of 20 mL allowed within 24 hours
  • eGFR less than 30 - GBCA cannot be administered except in cases of medical necessity; informed consent required; nephrology consultation required; hemodialysis should be considered
  • Very rarely that any patients with eGFR less than 30 would get contrast-enhanced MR exams (36 in 52 954 exams; 0.07%)
eGFR = estimated glomerular filtration rate; GBCA = gadolinium-based contrast agent

Wang Y, Alkasab TK, Narin O, et al. Incidence of nephrogenic systemic fibrosis after adoption of restrictive gadolinium-based contrast agent guidelines. Radiology 2011; 260:105-111.

July 15, 2011

The Price of Being a Doctor

How one patient makes a doctor question his decision to be a physician, while another does the opposite? Follow the link to the Insights on Residency Training blog by the Journal Watch.

July 11, 2011

Predictors of Cervical Spine Fractures and Fracture Risk

Flow diagram (originally published by Blackmore CC, et al, Radiology 1999) demonstrating a prediction rule for determination of risk of cervical spine fracture in blunt trauma patients. Percentages indicate the risk of fracture for each group with 95% CIs. Area under the ROC curve = 0.87

  • Three common options exist to "clear" cervical spine in trauma patients: clinical evaluation, radiography or CT
  • Canadian C-spine Rule (CCR) or NEXUS criteria are generally used by emergency physicians and trauma surgeons to determine which patients require imaging clearance
  • Among patients who, based on CCR or NEXUS, need imaging clearance: an issue exists whether to choose x-ray vs. CT
  • In general, CT is preferred for patients with moderate or high likelihood of having C-spine injury given its higher accuracy, cost-effectiveness and ease of performance. However, C-spine CT has not been tested as cost-effective among patients with low likelihood of C-spine injury - practice has been different from one place to another
According to Blackmore CC, et al
  • We can stratify patients into groups of different fracture probabilities by using 4 predictors: severe head injury, high-energy cause, age and focal neurologic deficit
  • Definition of severe head injury = intracranial hematoma, brain contusion, skull fracture or unconsciousness
  • Definition of high-energy cause = high-speed MVC (greater than 30 mph), pedestrian struck by car
  • Definition of moderate-energy cause = low-speed MVC, MVC at unknown speed, bicycle accident, motorcycle accident or fall
  • Definition of focal deficit = those that could be in a spinal cord or spinal nerve distribution

Blackmore CC, Emerson SS, Mann FA, Koepsell TD. Cervical spine imaging in patients with trauma: determination of fracture risk to optimize use. Radiology 1999; 211:759-765.

July 6, 2011

Child Abuse

A frontal radiograph of the femur demonstrates classic metaphyseal lesions of the distal femur and proximal tibia medially (arrows)

  • The two most common injuries in child abuse = soft tissue injuries and fractures
  • Failure to recognize child abuse may result in the child's return to hostile environment, leading to repeated injuries and possible death
  • Highly specific fractures = rib, spinous process, and sternal fractures and classic metaphyseal lesions
  • High suspicion = multiple fractures of differing ages
The Skeletal Survey
  • To evaluate children less than 2 years old for signs of physical abuse
  • American College of Radiology (ACR) recommends a single frontal view of each region of the appendicular skeleton (arms, forearms, thighs, legs, hands and feet), frontal and lateral views of the axial skeleton (skull, C-spine, LS spine and thorax) and a frontal view of the pelvis <=== these are a minimum of 20 radiographs
  • In a recent report of 930 abused children, prevalence of fractures was 34%. Skeletal survey added value in 13% of cases in which new fractures were discovered only at skeletal survey but not on prior imaging. Most fractures occur in long bones, ribs and skull. Pelvis, spine, hands and feet were much less common to be fractured (only 1% of all cases, which also had other fractures diagnostic of abuse). The authors called for eliminating x-rays of the pelvis, spine, hands and feet from skeletal survey performed for suspected child abuse
Karmazyn B, Lewis ME, Jennings SG, et al. Prevalence of uncommon fractures on skeletal surveys performed to evaluate for suspected abuse in 930 children: should practice guidelines change? AJR 2011; 197:W159-W163.

July 1, 2011

Obstructing Ureteric Stone on Ultrasound

Figure 1: A gray-scale ultrasound image of the right kidney shows right hydronephrosis and hydropelvis.
Figure 2: The scan in the right pelvis demonstrates an echogenic focus (arrow) with posterior acoustic shadowing (arrowheads) at the site where the ureter abruptly changes its caliber.

  • Imaging in patients presenting with renal colic is performed to 1) confirm the suspected renal colic, 2) diagnose cause and level of obstruction, 3) detect or rule out complications of renal colic (obstruction, infection), 4) detect alternative diagnoses
  • Non-contrast CT is current gold standard for diagnosis of urinary tract stone disease
  • Ultrasound may be an initial imaging done although its sensitivity is limited (37% - 64%) for detecting renal calculus (lower for ureteric calculus) and acute obstruction (74% - 85%)
Imaging Appearance
  • Stone (brightly echogenic focus with posterior acoustic shadowing). For renal stone less than 5 mm, ultrasound is of limited accuracy. Ureteric stone is uncommonly appreciated on US.
  • Hydronephrosis
  • Twinkling artifact behind the stone, and absent ureteral jet on color Doppler imaging
Scott LM, Sawyers SR, Bokhari J, Hamper UM. Ultrasound evaluation of the acute abdomen. Ultrasound Clin 2007;2:493-523.

June 26, 2011

Cerebral Venous Sinus Thrombosis (CVST)

Figure 1: Axial image of the brain shows ill-defined areas of hypoattenuation (stars) in bilateral frontal lobes involving both gray and white matter, in a nonarterial distribution.

Figure 2: A lateral view of CT venography shows occluded anterior 1/3 of the superior sagittal sinus (arrows).

  • 0.5% of all strokes
  • Peak incidence in neonates and adults in third decade of life (female:male = 5:1.5)
  • Clinical presentation varies widely from relatively mild symptoms to devastating hemorrhage
  • Risk factors following Virchow's triad: blood stasis, changes in vessel wall, and changes in blood composition
  • Intravenous heparin and subcutaneous low-molecular-weight heparin are primary Rx for acute CVST. Hemorrhage does not preclude the diagnosis.
  • Patient prognosis depends on location of CVST (best if in cortical vein, anterior superior sagittal sinus, isolated transverse and isolated sigmoid sinus) and extent of involvement (the more segments of veins involved, the greater complications)
  • Infarction or hemorrhagic infarction in non-arterial distribution
  • Delta sign = filling defect (clot) surrounded by enhanced venous blood in the affected sinus and dural enhancement
  • MRI shows T1 hyperintensity and lack of flow void
  • Look for potential etiology (and vice versa): paranasal sinus and mastoid infection
1. Qureshi AI. Textbook of interventional neurology. 2011
2. Castillo M. Neuroradiology companion: methods, guidelines and imaging fundamentals. 2006
3. Zubkov AY, McBane RD, Brown D, Rabinstein AA. Brain lesions in cerebral venous sinus thrombosis. Stroke 2009;40:1509

May 25, 2011

Tibial Plateau Fracture

An AP knee radiograph shows a fracture of the lateral tibial plateau (arrows) in an osteopenic patient who had a recent trauma.

  • Fractures involving the articular surface of the proximal tibia. This is a diverse group of fractures, a spectrum of different severity of injuries
  • Most common mechanism of injury is fall with knee forced into valgus or varus
  • Imaging performed to locate the fracture, identify fracture pattern and degrees of displacement
  • Most common location = lateral tibial plateau
  • Aim of surgical treatment is to restore or preserve limb alignment
  • Usually AP and lateral views of the knee show the fracture but bilateral oblique views are also recommended since many subtle joint impaction or fracture lines are not visible on the two views.
  • CT with reformations is a study of choice to delineate the extent, orientation of condyle, location and depth of articular comminution and impaction
  • Schatzker classification divides tibial plateau fractures into 6 types: lateral plateau without depression, lateral plateau with depression, lateral or central plateau compression, medial plateau, bicondylar plateau, plateau fracture with diaphyseal discontinuity.
  • Based on the classification, the management is different. The first three: repair the articular cartilage. The latter three: treatment depends on location of soft tissue injury.

Markhardt BK, Gross JM, Monu J. Schatzer classification of tibial plateau fractures: use of CT and MR imaging improves assessment. RadioGraphics 2009

May 10, 2011

Acute Sinusitis

Water's view radiograph of the paranasal sinus shows an air fluid level in the left maxillary sinus (arrows) of a 56-year-old man.

  • Very common disease encountered by primary care physicians.
  • Diagnostic imaging is generally used in cases of recurrent or complicated sinus disease.
  • Plain radiography has a limited role in management of sinusitis
  • Mucosal thickening, air-fluid levels, complete opacification of the involved sinus
  • Mucosal thickening seen in more than 90% of sinusitis case, but very nonspecific
  • More specific = air-fluid levels and complete opacification -- but seen in only 60% of cases
  • Interpretation can vary widely among observers, with a high rate of false-negative results
  • Radiography is not useful in patients younger than 3 years because of poorly developed sinuses
  • Because clinical judgment is sufficient to diagnose sinusitis in majority of cases, and empiric treatments are inexpensive and safe --- x-ray should be reserved for patients with persistent symptoms despite appropriate treatment.
Okuyemi KS, Tsue TT. Radiologic imaging in the management of sinusitis. Am Fam Physician 2002; 15;66:1882-1887

May 5, 2011

Acute Sigmoid Diverticulitis

Axial CT image demonstrates left colonic wall thickening, pericolonic fat stranding, fascial thickening (arrowheads) and an inflamed diverticulum (arrow).

Facts: Acute Diverticulitis
  • Diverticular disease found in 5-10% of people over the age of 45 years, and 80% by the age of 80
  • Diverticulitis is the most common complication of diverticular disease. It is found in 10-25% of people with diverticular disease at some point.
  • Most common site of diverticulitis = rectosigmoid colon
  • Diagnosis made on a basis of clinical history (pain, fever, diarrhea), examination (abdominal tenderness, palpable mass), lab (elevated inflammatory markers, leucocytosis) and imaging.
  • CT is considered the best imaging method for diagnosing diverticulitis and characterizing its complications
  • CT findings: diverticula, inflamed diverticula, pericolic fat stranding, colonic wall thickening, phlegmon, abscess, extraluminal air
  • Differentiating acute diverticulitis from malignancy can be a problem since many findings overlap. Suspicion for malignancy is high if there are pericolonic lymph nodes and the involved segment is short and eccentric.
Buckley O, Geoghegan T, O'Riordain DS, et al. Computed tomography in the imaging of colonic diverticulitis. Clin Radiol 2004; 59:977-983.

April 30, 2011

Anaplastic Astrocytoma

Axial T2W (fig. 1) and T1W post contrast (fig. 2) images of the brain demonstrate a large ill-defined mass (arrows) centered in the right insula with extension to the frontal and temporal lobes. The mass shows a heterogeneous high T2 signal intensity, cystic areas (arrowheads), mass effect and minimal enhancement.

Facts: WHO grading system for primary astrocytic tumor and imaging features
  • Grade I = circumscribed glioma including pilocytic astrocytoma -- no mass effect, no enhancement
  • Grade II = diffuse astrocytoma (cytological atypia alone) -- mass effect, no enhancement
  • Grade III = anaplastic astrocytoma (anaplasia and mitotic activity) -- complex enhancement
  • Grade IV = glioblastoma (also show microvascular proliferation) -- necrosis (ring enhancement)
  • Imaging grading is imprecise but can be used as a preliminary assessment
  • Grading is not applicable to pediatric patients or special astrocytomas
  • Low grade gliomas usually hypodense on CT, hypointense on T1WI and hyperintense on T2WI. High T2 signal intensity commonly extends beyond the tumor volume. Most do not enhance.
  • Anaplastic gliomas may or may not enhance. Calcifications and cysts occur in 10-20%.
  • Glioblastomas usually enhance on the rim, representing cellular tumor but tumor cells often extend beyond 1.5 cm of the enhanced ring. Nonenhancing center may represent necrosis or associated cyst.
  • On imaging, factors affecting prognosis are location (eloquent vs. non-eloquent) and tumor size
Our case: anaplastic astrocytoma.

Greenburg MS. Handbook of neurosurgery, 7th edition, 2010.

April 25, 2011


Bulleted ListFrontal radiograph of the hand demonstrates widening of the terminal tufts (between long arrows), bases of the distal phalanges, thickening of the digit soft tissues (between arrowheads) and widening of the metacarpophalangeal joints (between short arrows).

Facts: Acromegaly
  • Acromegaly = large extremities
  • Syndrome caused by hypersecretion of growth hormone (GH) secondary to pituitary adenoma, or hyperplasia.
  • GH hypersecretion leads to different skeletal manifestations depending on patient's age.
  • In mature skeleton (like in our patient), there is increased bone width and soft tissue enlargement particularly in the acral parts of the skeleton.
  • Complication: secondary osteoarthritis
  • Soft tissues: thickening of the digits, enthesopathy
  • Bones: bone enlargement, squaring of phalanges and metacarpals, spade-like terminal tufts
  • Joints: widening of joint spaces due to thickening of articular cartilage
Guglielmi G, Van Kuijk C, Genant HK. Fundamentals of hand and wrist imaging. Springer-Verlag 2001.

April 20, 2011

Swyer-James Syndrome

A frontal chest radiograph of a 56-year-old man demonstrates a unilateral left hyperlucent lung with a normal lung volume.

An axial inspiratory and expiratory (not shown) chest CT shows evidence of air trapping of the left lung parenchyma, parts of the right lung and cystic bronchiectases. Note small pulmonary arteries in the areas of air trapping.

Facts: Swyer-James Syndrome
  • Original description on x-ray: unilateral small lung with hyperlucency and air trapping
  • Typically a result of viral respiratory infection in infancy or childhood (it is a post-infectious form of bronchiolitis obliterans)
  • Diagnosis based on radiologic and clinical findings rather than pathologic examination. If pathologic examination is performed, there are bronchiolitis obliterans with various degrees of chronic inflammation, fibrosis and dilatation of airways and air spaces distal to the obstructed bronchioles.
  • Clinicians need to exclude other causes of air trapping such as obstructing tumor or foreign body
  • X-ray: unilateral hyperlucent lung, or bilateral asymmetric hyperlucency of the lungs. Lung volumes are usually decreased on the site of lucency, but can be normal or increased
  • CT: air trapping usually more extensive than on x-ray, and usually bilateral. May or may not have bronchiectasis
  • It is important to look for causes of air trapping on CT such as obstructing tumor or foreign body, as it may obviate the need for bronchoscopy
Moore ADA, Godwin JD, Dietrich PA, et al. Swyer-James syndrome: CT findings in eight patients. AJR 1992; 158:1211-1215.

April 15, 2011

Gastric Diverticulum

Fig. 1: Axial contrast-enhanced T1W MR image shows a mass (arrows) in the gastrohepatic ligament with internal low signal intensity, incidentally seen on the study performed for other reason in a young male.

Fig. 2: A coronal-reformatted CT image shows that the mass is filled with air and oral contrast material with a narrow communication (arrows) with the gastric lesser curvature.

Facts: Gastric Diverticulum
  • Incidence: 0.02% in autopsy studies, 0.04% on upper GI studies
  • True diverticula have complete wall, believed to be congenital. False diverticula are either traction or pulsion, and associated with inflammation or other diseases
  • True diverticula commonly arises from the posterior wall of the cardia, 2 cm below the EG junction or 3 cm from the lesser curvature.
  • Most are asymptomatic but they may cause epigastric pain, dysphagia, belching, bloating and early satiety.
  • Rare complications: bleeding, diverticulitis, perforation and cancer
  • Thin-walled, air-containing outpouching from the stomach. May contain fluid or gastric content
  • Size 1-5 cm, mostly less than 4 cm
  • If it is filled only with fluid, it can be difficult to differentiate from cystic tumor on cross-sectional imaging.
1. McKay R. Laparoscopic resection of a gastric diverticulum: a case report. JSLS 2005; 9:225-228.
2. Coakley F. Pearls and pitfalls in abdominal imaging: pseudotumors, variants and other difficult diagnoses. Cambridge University Press, 2010.

April 10, 2011

Hangman's Fracture

A lateral cervical spine radiograph shows grade I anterolisthesis of C2 on C3 (arrow) with fractures of the C2 pars interarticulares (arrowheads).

  • Traumatic spondylolisthesis of C2
  • Combination of soft tissue and bony injuries believed to start from anterior longitudinal ligament (ALL) tear, avulsion of C2/3 disc from either inferior or superior endplate - then bony malignment and posterior element fractures.
  • Posterior element fractures are often extra-articular, involving the pars interarticulares (pedicles)
  • Named "hangman" because of mechanism of injuries mimic that of hanging (neck hyperextension with compression of posterior elements)
  • Displaced fractures often are associated with neurologic injuries (apnea, complete paralysis, sensory loss distal to lesion)
Mandavia DP, Newton EJ, Demetriades D. Color Atlas of Emergency Trauma, 2003.

April 5, 2011

The Fat Pad Sign

A lateral radiograph of the elbow shows a posterior fat pad sign (arrows) and elevation of the anterior fat pad (arrowheads) in a patient with a radial neck fracture (seen anteriorly on this image).

  • Normal: elbow fat pads are intracapsular but extrasynovial, they are visible anteriorly to the elbow joint but not posteriorly.
  • Effusion: elevation of both anterior and posterior fat pads are seen on lateral x-ray
  • In an acute injury to the elbow, elevated posterior fat pad suggests the possibility of an intracapsular fracture
  • Most common causes in children are supracondylar fracture, lateral epicondyle and separation of medial epicondylar ossification center
  • Most common causes in adults are radial head or neck fractures, olecranon fractures, dislocations and fracture/dislocations
  • Value of the posterior fat pad sign depends on its ability to predict an occult fracture in the absence of a radiographically visible fracture
  • False-negative fat pad sign may occur if there is poor radiographic positioning, extracapsular abnormality or capsular rupture
  • False-positive fat pad sign can be seen when the elbow is extended
1. Goswami GK. The fat pad sign. Radiology 2002;222:419-420.
2. Skaggs DL, Mirzayan R. The posterior fat pad sign in association with occult fracture of the elbow in children. J Bone J Surg 1999;81:1429-1433.

March 30, 2011

Urethral Stone

An abdominal radiograph shows an oval calcification (arrow) in the midline below the pubic symphysis in a male patient with multiple small right renal calculi (arrowhead).

  • Urethral calculi in males are almost always secondary to stone disease elsewhere (bladder or kidneys), these are called "migrant calculi"
  • Primary stone formation within the urethra itself is very rare, but can be seen if stricture or urethral diverticulum is present
  • Large urethral calculi may lodge at the point of urethral narrowing such as the membranous urethra
  • Clinical: pain, bleeding and impaired urine flow, palpable stone in the perineum or underside of the penis
  • Treatment: distal stones may be grabbed by stone forceps and extracted via urethral meatus (requiring general anesthesia) or urethrolithotomy. Proximal stones may be pushed back into the bladder endoscopically, then extracted like a bladder stone
  • Although rare, the case highlights the need to specifically include the portion of urethra in abdominal radiograph performed to evaluate for stone disease and to actively search for stone in this region
  • On CT, urethral stone can easily be overlooked either because it is not imaged (the urethra not commonly included in a stone protocol CT) or missed by the reader
  1. Kawashima A, Sandler CM, Wasserman NF, et al. Imaging of urethral disease: a pictorial review. RadioGraphics 2004;24:S195-S216.
  2. Smith P. Urology - Medico-legal practitioner series. 2001