Imaging of Traumatic Brain Injury: Pearls and Pitfalls

This was presented at the 51st Annual Scientific Meeting of the Royal College of Radiologists of Thailand.

Renal Artery Variants in Patients with Normal Renal Function

3D volume rendered CT image shows a 2nd right renal artery (arrows) arising from the right common iliac artery

Facts

• "Normal" renal arterial arrangement = single bilateral renal arteries with hilar segmental branching. This occurred in 46% of cases in a landmark angiographic report published in 1978
• Normally, no intrarenal arterial anastomoses are present. Each artery represents an end artery -- interruption results in infarction of that segment
• Variations include double renal arteries, triple renal arteries, pre-hilar segmental branching, fetal lobulation and exaggerated size difference (greater than 2 cm). 
• Most common variations are multiple renal arteries followed by pre-hilar segmental branching

Knowledge of Renal Vascular Variations is Important For:

• Renal transplantation
• Renovascular hypertension
• Vascular reconstruction for congenital and acquired lesions
• Reconstructive surgery for abdominal aortic aneurysms

Our case: Double right renal artery with the smaller branch originating from the common iliac artery

Reference:

- Harrison, Jr., et al. Incidence of anatomical variants in renal vasculature in the presence of normal renal function. Ann Surg 1978;188:83-89.

- Ozkan U, et al. Renal artery origins and variations: angiographic evaluation of 855 consecutive patients. Diagn Interv Radiol 2006;12:183-6.

Vertebral Artery Hypoplasia

Curved reformat of the normal-caliber right vertebral artery showing all 4 segments of the artery. 

Curved reformat of the left vertebral artery shows diffuse, small caliber of the artery.

Facts:

• Operational definitions are either 1) asymmetrical ratio of or greater than 1:1.7, or 2) discrepancy of greater than 2 mm diameter
• Prevalence 2%-6% of population (from autopsy and angiographic series)

Clinical Relevance

• Posterior circulation ischemia: hypoplasia leads to reduction of posterior circulation blood flow velocity therefore has a negative role in occlusion of major cerebral arteries
• Migraine with aura and vestibular neuronitis: hypoplasia is believed to be associated with regional hypo perfusion and complex neurovascular consequences

Reference:

Chuang YM, Chan L, Wu HM, et al. The clinical relevance of vertebral artery hypoplasia. Acta Neurol Taiwan 2012;21:1-7.

Fatty Liver

Axial "in-phase" MR image shows increased signal intensity of the liver.

Axial "opposed-phase" MR image shows decreased signal of the entire liver when compared with the same areas on in-phase image. 

Facts

• Triglyceride accumulation within cytoplasm of hepatocytes
• Can be due to alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, drugs
• May progress to steatohepatitis and cirrhosis
• Avoid the use of "fatty infiltration of the liver", which is misleading because fat deposition in Fatty Liver is in hepatocytes - rarely in other cell types
• Sensitivity/specificity for detection:
• Ultrasound = 60-100% / 77-95%
• Non-contrast CT = 43-95% / 90%
• Chemical-shift MRI = 81% / 100%

MR Imaging

• Because protons in water and fatty acid molecules precess in different resonance frequency, proton chemical shift imaging can be utilized to image this difference
• If images are obtained when fat and water protons are "in-phase", their signals are additive (brighter). If they are "out-of-phase", their signals cancel each other (structure becoming darker)
• Amount of hepatic fat can be quantified by assessing the degree of signal loss

Reference

Hamer OW, Aguirre DA, Casola G, et al. Fatty liver: imaging patterns and pitfalls. Radiographics 2006; 26:1637-1653.

Focal Urinary Bladder Wall Thickening

Axial and sagittal-reformatted CT images show focal thickening of the posterior wall of the urinary bladder (arrows) with increased enhancement relative to normal bladder wall. 

Differential Diagnosis

• Tumor (benign, malignant, metastasis)
• Adherent clot
• Infection/inflammation (TB, cystitis cystica/glandularis, malakoplakia, schistosomiasis)
• Trauma (mural hematoma)
• Extravesical pathologies (spread of extravesical inflammation or tumor, endometriosis)

Facts

• Transitional cell carcinoma accounts for most focal bladder masses
• Most of the time it is impossible to distinguish tumor from other causes of focal wall abnormality and cystoscopy is necessary

Our case: Transitional cell carcinoma in a 73-year-old female

Reference

Patel U. Imaging And Urodynamics Of The Lower Urinary Tract. Springer 2010.

Bhargava. Ultrasound Differential Diagnosis. Jaypee Brothers Publishers, 2005.

Krukenberg Tumors

Axial and coronal-reformatted CT images of a 41-year-old woman shows an enlarged, solid-appearing right ovarian mass (arrows). The left ovary (not shown) is normal. 

Facts:

• Metastatic tumor to the ovary that contains mucin-secreting, signet ring cells
• Usually originate from primary tumors of GI tract (most common = colon and stomach)
• 10% of all ovarian tumors
• Occur in reproductive age

Imaging:

• Nonspecific appearance. Can be solid or mixed solid/cystic
• High suspicion for ovarian metastasis if:
• Bilateral 
• Complex-appearing ovarian masses
• Known GI tract tumor (esp. colon and stomach)
• MRI showing T1/T2 hyper intensity due to mucin

Our case: Ovarian metastasis from primary gastric cancer.

Reference:

Jung SE, et al. CT and MR imaging of ovarian tumors with emphasis on differential diagnosis. Radiographics 2002; 22:1305.

Slideshow: Imaging of Facial Trauma

Slideshow: Imaging of Non-traumatic Intracranial Hemorrhages

Imaging of Non-traumatic Intracranial Hemorrhage from Rathachai Kaewlai

Prepare for AOCR 2014

This year, the largest radiology meeting in Asia will be held in Kobe, Japan!

Many big names in radiology from around the world will be joining as invited speakers including JKT Lee, AR Margulis, M Prokop, D Resnick and H Hricak.

Scientific programs include all radiology subspecialties with interesting additions of IT, Radiation Safety and Emergency Radiology.

Kobe is an international port city with a long historical importance. The city is famous for European bakeries, Kobe beef, and fresh seafood. Sightseeing spots like Kyoto, Osaka, Nara and Hiroshima are reachable by day trips. During this time of the year, Kobe temperature ranges between 21 and 29 degrees Celsius. 

Details and registration information can be found at this LINK.

Enhanced Intervertebral Disc in Post-discectomy Patients

Sagittal, fat-suppressed T1W MR images of the spine without (above) and with (below) IV contrast show two band enhancement of L4/5 disc (arrows), which parallel to the endplates of an asymptomatic post remote-discectomy patient. 

 Facts: Imaging of Postoperative Lumbar Discectomy

• Intervertebral disc enhancement, annular enhancement and vertebral body enhancement are generally suggestive signs of disc space infection in post-discectomy patients
• However, some patients without clinical signs/symptoms of infection may have abnormal enhancement of disc/endplate and annulus. 
• In a study of 94 patients without clinical infection, post-operative MRI (3-6 months after surgery) shows anular enhancement in almost all cases and 20% of patients have disc enhancement that are not present on preoperative MRI
• Suggestive pattern of "incidental" enhancement: linear enhancement within the disc (two thin bands paralleling the end plates). Authors postulate that this could be due to accelerated degenerative disc change, unrelated to infection

Reference:

Ross JS, Zepp R, Modic MT. The postoperative lumbar spine: enhanced MR evaluation of the intervertebral disk. AJNR Am J Neuroradiol 1996;17:323-331.

Tracheal Bronchus

Axial and coronal-reformatted CT images in a patient with tuberculosis of the right upper lobe (stars) show a tracheal bronchus (arrows) arising from the right lateral wall of the trachea, within 2 cm of the carina. Note a normal-appearing right upper lobe bronchus (arrowhead). 

Facts

• Abnormal bronchus arising directly from the lateral wall of the trachea (on either side, but right side is more common), supplying the upper lobes
• 0.1% - 2% incidence
• Most cases are found incidentally on bronchoscopy or CT
• Associated with other anomalies such as ribs, vertebrae

Types

• Two types: displaced, or supernumerary
• "Displaced" type = RUL bronchus or any of its segmental bronchus in cephalad location than normal. If the entire RUL bronchus arises from tracheal wall, it is called "bronchus suis"
• "Supernumerary" type = normal RUL bronchus and its segmental bronchi but there is extra bronchus arising directly off the lateral wall of the trachea

Clinical implications

• In children, it is associated with recurrent infections, stridor, respiratory distress and thoracic masses
• In adults, it can complicate endotracheal intubation (occlusion or accidental intubation of a tracheal bronchus can cause atelectasis)

Our case: supernumerary bronchus arising from the right lateral wall of the trachea. The patient presented with TB of the right upper lobe. 

Reference:

Aoun NY, et al. Tracheal bronchus. Respir Care 2004;49:1056-8.

Gastric Emptying Scintigraphy: SNM Recommendation

Facts: Gastric Emptying Scintigraphy

• Performed to evaluate patients with symptoms suggesting alteration of gastric emptying or motility
• Provide physiologic, noninvasive, quantitative measurement of solid or liquid gastric emptying
• Used to diagnose delayed gastric emptying (ie, gastroparesis) or rapid emptying (dumping syndrome)

Factors affecting gastric emptying (potentially creating false-positive or false-negative tests)

• Medications: prokinetics (shorten gastric emptying), narcotic analgesics (prolong gastric emptying)
• Tobacco smoking (prolong gastric emptying)
• Hyperglycemia (prolong gastric emptying)
• Premenopausal status (prolong gastric emptying)

Standards for performing GES as recommended by Society of Nuclear Medicine (SNM)

• Full recommendation paper (link) provides recommended timing of imaging, composition of meal, glycemic control, monitoring of symptoms and assessment of severity
• Low-fat, egg white meal
• Imaging at a minimum at 0,1,2 and 4 hours after radiolabeled meal ingestion

Tuberous Sclerosis Complex

Axial T1W MR image of a 5-year-old girl demonstrates several T1-hyperintense subependymal nodules arrows).

Coronal FLAIR MR image shows multiple cortical tubers and subcortical white matter hyperintensities (asterisks).

Facts

• Autosomal dominant disorder due to abnormality of TSC1 and TSC2 genes
• Most frequent clinical manifestations are neurologic (myoclonic seizures in early childhood, psychiatric symptoms, retinal hamartomas) and skin (adenomas of sebaceous glands)

Diagnostic Criteria by Tuberous Sclerosis Complex Consensus Conference (Maryland 1998)

Major features

• Facial angiofibromas or forehead plaque
• Nontraumatic ungual or periungual fibroma
• Hypomelanotic macules (more than 3)
• Shagreen patch (connective tissue nevus)
• Cortical tuber
• Subependymal nodule
• Subependymal giant cell astrocytoma
• Multiple retinal nodular hamartomas
• Cardiac rhabdomyoma, single or multiple
• Lymphangiomyomatosis (LAM)
• Renal angiomyolipoma (AML)

Minor features

• Multiple randomly distributed pits in dental enamel
• Hamartomatous rectal polyps
• Bone cysts
• Cerebral white matter "migration tracts"
• Gingival fibromas
• Nonrenal hamartoma
• Retinal achromic patch
• Confetti skin lesions
• Multiple renal cysts

Definite TSC: Either 2 major, or 1 major + 2 minor features

Probable TSC: One major + one minor feature

Possible TSC: Either 1 major, or 2 or more minor features

----

Imaging findings are highlighted in red.

When both LAM and renal AML are present, other features should be present as well before definite diagnosis is made. 

Reference:

Roach ES, Sparagana SP. Diagnosis of tuberous sclerosis complex. J Child Neurol 2004;19:643-649. Fulltext

Metatarsal Stress Fracture

Oblique radiographic view of the foot shows transverse fracture lines of the proximal diaphyses of the forth and fifth metatarsals (arrows). Note sclerotic bone ends, periosteal reaction and minimal widening of the fracture gaps (degree of sclerosis is more on the forth digit)

Facts

• Spontaneous fractures of normal bone that result from summation of stresses
• Most common lower-extremity stress fracture
• Originally termed "march fracture" (seen in military recruits). Now seen in ballet, football, gymnastics and basketball
• Most common site = shaft (at diaphysis or neck)
• Increased incidence in pes cavus and pes planus foot

Radiography

• Often negative in early phase. May see thickening of cortex and small periosteal reaction
• Later, a fracture line with sclerotic bone ends, periosteal reaction, widening of fracture gap will be shown. 
• Late phase, the bone ends involved are entirely sclerotic 

References:

Schepsis AA, Busconi BD. Sports Medicine, 2006.

Baxter DE, Porter DA, Schon L. Baxter's the Foot and Ankle in Sport, 2008. 

Colonic Lymphoma

Axial (top) and coronal-reformatted (bottom) CT images show partial circumferential wall thickening (arrows) of the descending colon (C). Note smooth margin and homogeneous enhancement of bowel wall thickening, and disproportionate lack of colonic narrowing despite a large lesion. 

Facts:

• Lymphoma accounts for 0.2% - 1.2% of all colon malignancies
• Most common form of GI tract lymphoma is non-Hodgkin lymphoma (NHL)
• Most common sites of GI tract lymphoma is stomach, followed by small bowel
• For colonic lymphoma, most common site is cecum
• Nonspecific clinical signs and symptoms
• Due to rarity, Rx is not standardized. Often, it is surgically resected then chemotherapy is given

CT patterns of GI tract lymphoma:

• Nodular thickening of bowel wall
• Discrete polyp (causing intussusception)
• Long, distensible infiltrative lesion with ill-defined, thick walls with aneurysmal dilatation of the lumen
• Large exoenteric mass extending into adjacent soft tissues

Features differentiating lymphoma from adenocarcinoma of GI tract

• Bulky lymphadenopathy (lymphoma more likely)
• Marked luminal dilatation of bowel segment that is involved (lymphoma more likely)

Our case: Colonic mucosa-associated lymphoid tissue (MALT) lymphoma in a 67-year-old man.

References:

Buckley JA, Fishman EK. CT evaluation of small bowel neoplasms: spectrum of disease. Radiographics 1998;18:379.

Bairey O, et al. Non-Hodgkin lymphomas of the colon. Hematol 2006;8:832.

Sellar Mass with Calcification

Sagittal images (upper left = CT, upper right = T2W MR, lower left = T1W MR, lower right = T1W post-contrast MR) of the pituitary region of an elderly individual show a large sellar/suprasellar mass with internal calcification (hyperdense on CT, signal loss on MR). The mass is mostly solid and reveals heterogeneous enhancement. Note ballooning of the sella.

Differential diagnosis of a calcified sellar mass:

• Craniopharyngioma (most likely)
• Pituitary adenoma (unlikely, 0.2% - 8% have calcification)
• Rathke's cleft cyst (rare disease)
• Chordoma (rare disease)

Associated findings that help DDx:

• Nodular appearance of calcification --> craniopharyngioma
• Calcifications in a cystic mass --> craniopharyngioma
• Curvilinear appearance of calcification --> pituitary adenoma or Rathke's cleft cyst
• Bone destruction --> chordoma

This is a rare case of sellar/suprasellar chondrosarcoma confirmed with histology. 

Reference:

Kasliwal MK, Sharma BS. A rare case of pituitary adenoma with calcification: a case report. Turkish Neurosurg 2008;18:232-235

Glezer A, et al. Rare sellar lesions. Endocrinol Metab Clin N Am 2008;37:195-211. 

Uterine Leiomyoma on MRI

Leiomyoma in a 28-year-old woman. Sagittal MR images in T2W (A), T1W (B) and post-contrast T1W (C) show a large, rounded, circumscribed mass in the anterior wall of the uterus (U) that pushes the bladder (B) anteriorly. The mass demonstrates T2 hypointensity, T1 isointensity and heterogeneous enhancement. 

Facts

• Most common uterine neoplasms with prevalence up to 40% of women of reproductive age
• Benign tumors of smooth muscle with variable amount of fibrous tissue
• Surrounded by pseudocapsule and supplied by one or two large vessels
• Greater than 90% from uterine body
• Classified on their position relative to uterine wall (submucosal, intramural or subserosal)

MR Imaging Findings

• Well-circumscribed mass
• Classic signal intensity: T1 isointensity, T2 hypointensity, variable enhancement
• If T1 hyperintense, think hemorrhage
• If T2 hyperintense, think cellular leiomyoma
• If no enhancement, think partially or completely infarcted leiomyoma

References

Hricak H. MRI of the pelvis: a text atlas

Hamm B, et al. MRI and CT of the female pelvis. 

Tibial Spine Fracture in Adults

A lateral knee radiograph of a 22-year-old man sustaining motor vehicle collision demonstrates an oval bone fragment (arrow) in the intercondylar region of the knee. There is complete separation between the fragment and the donor site with superior displacement of the fragment. Note hemarthrosis (asterisk).

Facts:

• Classically described in pediatric patients and considered the childhood equivalent of anterior cruciate ligament (ACL) ruptures in adults
• Forceful hyperextension of the knee resulting in avulsive force/tension on ACL, which inserts into the anterior tibial spine. Possibly with valgus stress or rotation. 
• In adults, most injuries occur in road-traffic accidents and are isolated
• Adults more likely to have associated tear of medial collateral ligament (MCL) or intra-articular fracture

Classification (Meyers and McKeever)

• Based on degree of displacement. Type II & III are most common
• Type I = incomplete avulsion of tibial spine without displacement
• Type II = incomplete avulsion with anterior elevation of the fragment
• Type IIIA = complete separation of fragment
• Type IIIB = rotated and comminuted fragment
• Generally, types I and II are managed conservatively while type III fractures are managed arthroscopically or with open reduction

References:

Kendall NS, et al. Fracture of the tibial spine in adults and children. J Bone J Surg [Br] 1992;74-B:848-52.

Rosen's Emergency Medicine - Concepts and Clinical Practice

Sarcoidosis on PET/CT

(A) MIP image from a PET/CT shows areas of FDG avidity in multiple lymph node stations including hilar, mediastinal, axillary, upper abdominal and groin regions. Note intense uptake of the spleen. 

(B&C) Axial fused PET/CT images show intense FDG uptake within thoracic, axillary nodes and spleen. 

PET/CT: Three patterns of sarcoidosis

1. Typical: Bilateral hilar uptake extending to the mediastinum with bilateral lung uptakes (PET and CT concordant lesions). This is found in the majority of cases (about 2/3)
2. Discrepant: Multiple foci of uptake in and outside chest, along with splenic uptake (PET and CT discordant lesions). Fewer lesions are seen on CT than on PET. This pattern is the 2nd most common and is indistinguishable from malignancy (esp. metastasis, lymphoma)
3. Multiple small FDG avid lung lesions: This pattern is similar to lung metastasis. Fortunately, it is the least common pattern. 

Our case: Biopsy-confirmed sarcoidosis involving the hilar, mediastinal, upper abdominal lymph nodes, and spleen. This follows the "discrepant" pattern (basically meaning that malignancy cannot be reliably distinguished)

References:

Alavi A, et al. Positron emission tomography imaging in nonmalignant thoracic disorders. Semin Nucl Med 2002;32:293-321.

Pulmonary Infarction

Chest x-ray demonstrates a peripheral airspace opacity (arrows) that has a wedge-shaped configuration and a blunt medial apex pointing toward the hilum

Coronal-reformatted CT images confirm the presence of airspace opacity in the right middle lobe (arrows) with an embolus in the corresponding segmental pulmonary artery (arrowhead)

Facts: 

• Pulmonary embolic obstruction can occur with or without resultant pulmonary infarction
• In pulmonary embolism with infarction, process begins as "incomplete" infarct (intra-alveolar hemorrhage without necrosis of alveolar wall), which can go on to necrosis "infarct" especially in patients with underlying unhealthy lung
• On CXR, infarct is seen as a wedge-shaped, pleural-based consolidation with a rounded convex apex directing toward the hilum "Hampton hump"
• Often occurs in lower lobes
• Heals with scar formation

Reference

Dalen JE. Pulmonary embolism: what have we learned since Virchow? Chest 2002; 122:1440-1456.

Color Doppler Twinkling Artifact

Longitudinal images of the left kidney show a stone (arrow) in the lower pole with posterior acoustic shadowing and the color Doppler twinkling artifact (short arrows).

Facts:

• Rapidly alternating red and blue signal behind a highly reflective structure on color Doppler US
• Useful diagnostic signs especially for urinary calculi detection and improved diagnostic confidence
• Can also be seen in calcifications in various tissues, biliary stones, encrusted indwelling urinary stents, gallbladder adenomyomatosis and bile duct hamartomas
• Two proposed mechanisms:
• Phase jitter - intrinsic machine noise causing random fluctuation of acoustic waves
• Acoustic waves hitting a rough interface producing complex beam pattern with multiple reflections

Reference

Kim HC, et al. Color Doppler twinkling artifacts in various conditions during abdominal and pelvic sonography. J Ultrasound Med 2010; 29:621.

Emphysematous Cystitis

Sagittal-plane ultrasound image of the bladder shows a linear hyperechoic structure with posterior "dirty shadowing" in the anterior aspect of the urinary bladder. There is no recent bladder catheterization. Upon decubitus positioning, this abnormality is immobile, suggesting extraluminal location. 

Axial non-contrast CT of the same patient demonstrates gas within the anterior and posterior walls of the urinary bladder (arrows).

Facts:

• Rare bladder inflammation with gas in bladder wall and surrounding tissues
• Generally caused by E.coli, K.pneumoniae or anaerobic gas-forming organisms
• Pathology: numerous gas filled intramural cysts on mucosal surface
• Risk factors: diabetes, immunocompromised state, urinary tract obstruction
• Most patients have mild forms of disease and respond well to antibiotics. Some have severe inflammation, gangrene and sepsis

Imaging:

• X-ray and CT usually is diagnostic with gas in the bladder wall, surrounding tissues and in the lumen in the absence of prior catheterization
• Ultrasound may show gas in the wall as hyperechoic lesions with posterior dirty shadowing. Visualization of posterior wall of urinary bladder may be limited if gas is present in the anterior aspect of the bladder. Decubitus scan helps localizing gas, whether inside the bladder lumen or in the wall
• CT helps detecting complications such as perforation or emphysematous pyelonephritis

Reference

Gillenwater JY, et al. Adult and pediatric urology, volume 1, 2002.

Petersen RO, et al. Urologic pathology, 2009.

Who Should Get CT Screening for Lung Cancer? USPSTF Reveals

Who Should Get CT Screening for Lung Cancer?

• Adults 55-80 years with a 30 pack-year smoking history AND currently smoke
• Adults 55-80 years with a 30 pack-year smoking history AND have quit within the past 15 years

Screening Should Be Discontinued If:

• Once a person has not smoked for 15 years
• Once a person develops a health problem that substantially limits life expectancy or ability/willingness to have curative lung surgery

Reference:

Moyer VA on behalf of the U.S. Preventive Services Task Force. 

Moyer VA et al. Screening for lung cancer: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med 2013 Dec 31; [e-pub ahead of print].