Radiology in Thai

Figure 1: Axial unenhanced CT image of the brain shows an isodense mass in the left posterior fossa with minimal, if any, mass effect.
Figure 2: Axial contrast-enhanced T1W MR image shows a large homogeneously enhancing extra-axial mass (star) near the left petrous bone overlying the sigmoid venous sinus (arrow).
Facts: Meningioma

• Tumors of meningeal cells (typically arising from meninges but can also be found in the choroid plexus, tela choroidea and arachnoid villi); therefore meningiomas can be seen in the meninges, spinal canal, intraventricular, and pineal regions
• Common, greater than 20% of all primary intracranial neoplasms
• Female:male = 3:2 to 2:1; mostly in late middle age
• Pathology: benign, atypical and malignant

Imaging Features

• Homogeneous, lobulated, well-circumscribed mass with uniform dense enhancement following contrast administration
• Common locations: parasagittal > convexity > sphenoid ridge
• High attenuation on unenhanced CT, iso- to mildly hypointense on T1W MR images
• May calcify in up to 1/4 of all cases, best seen on CT. Calcifications can be microscopic, punctate, large, peripheral or central. Malignant meningiomas rarely calcify.
• Hyperostosis can be seen in up to 1/2 of cases that meningiomas are immediately adjacent to the bone. Common in 'en plaque' meningioma
• Uncommon to have bone destruction (if pure destruction think of metastasis, sarcoma or myeloma)

Our case: benign meningioma overlying the sigmoid sinus without invasion. It is important to note if the meningioma is adjacent vascular structures for optimal surgical planning.
References:1. Drevelegas A. Imaging of brain tumors with histological correlation, 2002.2. DeAngelis LM, Gutin PH, Leibel SA. Intracranial tumors: diagnosis and treatment, 2002.

Lateral view of the knee radiograph shows focal cortical irregularity and thickening at the posterior aspect of the medial condyle of the femur (arrow), consistent with a cortical desmoid. The arrowhead points to a fabella.
Facts: Cortical Desmoid

• Considered to be an avulsion of the medial supracondylar ridge of the distal femur
• Occurs only on the posteromedial epicondyle of the femur (insertion of adductor magnus aponeurosis)
• Common in older children
• Patients may complain of pain, or being asymptomatic (incidentally detected on radiograph done for other reasons)
• They may or may not show periosteal reaction; 1-3 cm in size, mixed sclerosis and lucency in the cortex

Reference:Helms CA. Fundamentals of skeletal radiology, 3rd edition, 2005.

A coronal-reformatted CT image (without IV contrast) shows an obstructing right ureterovesical junction (UVJ) stone (arrow), causing hydroureteronephrosis. There is enlargement of the right kidney with perinephric stranding (arrowheads) as a result.
Facts:

• Urolithiasis incidence in the U.S. and Europe approximately 0.1% - 0.4% of population
• Male to female ratio = 3:1
• Peak age during third to fifth decade of life
• Recurrence rate about 75% during 20 years

Detection Rates by Various Imaging Methods

• Conventional radiography 50-70%
• Intravenous urography (IVU) 70-90%
• Ultrasound 50-60%
• Normal-dose CT: sensitivity 94-100%, specificity 97%
• Low-dose CT: sensitivity 95%, specificity 95%

Advantages of CT over IVU

• Shorter examination time
• Avoid cost and complications of IV contrast
• Greater sensitivity for stone detection
• Higher potential for detection of abnormalities unrelated to stone disease
• Study directly compared low-dose (<>
• Meta-analysis of 7 studies of low-dose CT in 1061 patients showing 95% sensitivity and specificity for stone diagnosis

References1. Liu W, Esler SJ, Kenny BJ, et al. Low-dose nonenhanced helical CT of renal colic: assessment of ureteric stone detection and measurement of effective dose equivalent. Radiology 2000;215:51-54.2. Niemann T, Kollmann T, Bongartz G. Diagnostic performance of low-dose CT for the detection of urolithiasis: a meta-analysis. AJR 2008;191:396-401.

Figure 1: Frontal radiograph of the right wrist shows no apparent fracture. In retrospect, there may be slight indistinctness of the "eye" of the hamate hook.
Figure 2: Axial CT image at the level of the hamate shows a nondisplace fracture near the base of the hamate hook (arrow).
Facts:

• Uncommon fracture that is easily missed on radiography
• Hook of hamate fracture is more common than fracture of the hamate body
• Direct blow to the hook, or avulsion of transverse carpal ligament and pisohamate ligament
• Presenting with pain on ulnar side of the palm aggravated by grasp, point tenderness over the hook at 1 cm distal and radial to the pisiform
• Best seen on carpal tunnel view (radiography) or CT
• If displaced and untreated, avascular necrosis and nonunion may occur.

Imaging Features

• On frontal radiograph, there is absence or indistinctness of the "eye" of hamate (oval, dense cortical ring shadow over the hamate)
• On CT scan, the fracture line is apparent at the hook best seen on axial images. It can involve the tip or the base of the hook

Reference:Singh AK, Kaewlai R. Extremity Trauma. In: Soto and Lucey's Emergency Radiology the Requisites, 2008.

Axial CT image shows a 5-cm heterogeneous left adrenal mass (arrows) with ill-defined border anterolaterally, and a liver mass (arrowhead).
Facts: Adrenal Cortical Carcinoma (ACC)

• Rare tumor, 0.5 to 2 cases per million population
• Bimodal age peak - young children, and adults in 4th to 5th decades
• Male = female
• Tumor arises from adrenal cortex; 50% produces hormones (cortisol, androgens)
• Most common site of metastasis: liver and lung

Adrenal Masses: Size Matters

• Mass less than 2 cm: incidence of malignancy 1%
• 2-4 cm: 3% - 8%
• 4-6 cm: 8% - 25%
• Greater than 6 cm: 40% - 80%

Imaging Features

• CT or MRI can suggest the diagnosis if there is malignant feature: venous invasion and/or capsular invasion, metastasis to lymph nodes or other organs.
• Mass usually is large, 70% of ACC are larger than 6 cm on imaging
• Usually heterogeneous after contrast administration
• 30% are calcified (usually central)
• Enlarged lymph nodes seen in 1/3 of cases (usually at high para-aortic or paracaval)
• MRI may be used as an adjunct to CT for delineation of IVC invasion and extension

Our case: adrenal cortical carcinoma
References:1. DeVita VT, et al. DeVita, Hellman, and Rosenberg's Cancer: Principles & Practice of Oncology, 8th edition, 2008

2. Husband JE, Reznek RH. Imaging in Oncology, Volume 1, 2nd edition, 2004.

A scout CT image shows a linear gas in the right upper quadrant running in an inferolateral to superomedial orientation (arrows). There is gas in the left colonic wall (arrowheads).
Facts: Pneumoperitoneum on Upright Radiograph

• As little as 1mm of free gas can be detected on radiography in an upright position with a horizontal x-ray beam
• If the patient cannot stay upright, a lateral decubitus (preferably patient on the left side) can be performed. Free gas will collect between lateral liver margin and abdominal wall
• Best chance of detection of free gas is when the radiograph is taken after the patient remains in an upright (or lateral decubitus) position for 10 minutes

Facts: Pneumoperitoneum on Supine Radiograph

• More difficult to detect
• Large free gas can be seen indirect as gas collect in different locations
• Right upper quadrant features include 1) linear gas collection running in an inferolateral to superomedial orientation (representing gas in subhepatic space, as in our patient), 2) triangular gas collection right to the spine above the kidney shadow (gas in most posterior recess of the Morrison pouch)
• Visualization of the outer wall of intestine (Rigler's sign)
• Visualization of the falciform ligament of the liver

Our case: pneumoperitoneum due to perforated ischemic colitis.
Reference:

1. Eisenberg RL. Gastrointestinal Radiology: a Pattern Approach, 4th edition, 2003.

2. Menuck L, Siemers. Pneumoperitoneum: importance of right upper quadrant features. AJR 1976;127:753-756.

A frontal chest radiograph shows double density to the right of the spine (short arrows) and convex border of the left atrial appendage (long arrows).A lateral view of the chest shows posterior displacement of the left mainstem bronchus by an enlarged left atrium (arrowheads).
Signs of Left Atrial Enlargement (LAE) on Chest Radiography

• Convex left atrial appendage
• Double density on the right side of the spine (one of the earliest signs)
• Double density on the left side as the left atrium extends into the left lower lobe
• Posterior displacement of the left mainstem bronchus posteriorly on lateral view, and superiorly on frontal view
• Spreading of the carina

Common Causes of LAE

• Acquired: mitral valve disease (stenosis or regurgitation), left ventricular failure, left atrial myxoma
• Congenital: VSD, PDA, hypoplastic left heart complex

Our case: severe mitral regurgitation
Reference: Miller SW, Boxt LM, Abbara S. Cardiac Imaging the Requisites, 2009, 3rd edition.

Supine chest radiograph in an ICU patient shows the tip of an NG tube in the right lower lobe bronchus (arrow). New opacities are seen in the vicinity of the tip of the NG tube, which may represent hemorrhage or aspiration.
Facts:

• Incidence in ICU patients between 0.5% - 1.5% of all NG tube placement
• Right side more common than left, lower lobe more than intermediate bronchus or main bronchus
• In one study of 14 malpositions, nearly half of the cases had subsequent pneumothorax requiring chest tubes, and the other half experienced pneumonias at the same site
• Traditional criteria for determining proper positioning of an NG tube (i.e., sound heard over the stomach upon insufflation of air, aspiration of fluid, absence of coughing) may not work well in ICU patients who are usually obtunded, intubated, have impaired gag reflex, decreased laryngeal sensitivity and are on neuromuscular blocking agents.
• Routine radiography after placement of an NG tube in ICU patients can be helpful for detection of tube malposition
• Once detected intrabronchial NG tube malposition, one should look for evidence of pneumothorax. If not seen, a close follow up radiograph is recommended since delayed pneumothorax may occur.

Reference:

Bankier AA, Wiesmayr MN, Henk C, et al. Radiographic detection of intrabronchial malpositions of nasogastric tubes and subsequent complications in intensive care unit patients. Intens Care Medicine 1997;23:406-410.

Please click on images to view a larger versionRoutine swimmer's view (left images) shows slight anterolisthesis of C7 on T1, in a trauma patient who sustained neck injury but normal CT scan. A repeat swimmer's view focusing at the lower cervical spine was performed and show normal alignment.
Swimmer's View Lateral Cervical Radiograph

• Usually required to visualize C7-T1 junction. In one study, only 20% of cases receiving five-view cervical radiography (AP, lateral, bilateral obliques and odontoid) C7-T1 can be adequately seen.
• Downsides of this view are: high dose, high scatter, difficult positioning, usually not adequate on large patients or patients with shoulder injuries
• To visualize C7-T1 junction, one should avoid arm pulling in patients who sustained a cervical spine injury

Current Practice

• Now, most places replace cervical spine radiography with CT scan because of higher sensitivity for fracture, shorter scan time, and probably less costly (if combined the use of overall resources)
• Some institutions still perform an out-of-collar lateral radiograph after a negative CT scan to ensure no significant change in alignment that may occur in patients with isolated ligamentous injury not shown on CT. This exam usually includes lateral and swimmer's radiographs.

This case show a subtle malalignment seen on routine C7-T1 junction on a routine swimmer's view. This was cleared by repeating the study with a focus at lower cervical spine. Abnormality on the first image is believed to be due to different centering of x-ray beam and superimposition of structures.
Reference:1. Daffner RH. Cervical radiography for trauma patients a time-effective technique? AJR 2000;175:1309-1311.2. www.Wikiradiography.com

Axial CT images of the sinuses show complete opacification of the maxillary, ethmoid and sphenoid sinuses with widening of the sinus ostia (yellow stars) and opacity in the nasal passages (blue stars) in this patient with history of allergic rhinitis.
Facts: Sinonasal Polyposis

• Common finding in patients with chronic rhinosinusitis (2% - 16% of cases)
• Soft, yellow-white nasal polyps that consist of edematous stroma with eosinophilic infiltrates, covered by respiratory epithelium
• Predisposing factors: asthma, fungal sinusitis, Kartagener syndrome, ASA syndrome, cystic fibrosis
• Can be seen in healthy individual with no predisposition to polyps
• Usually multiple, bilateral polyps. Majority of polyps arise from uncinate-turbinate-infundibulum space and bulla-hiatus seminularis-infundibulum
• On CT, there is opacification of the sinuses with widening of the sinus ostium and sinonasal passages

References1. Maroldi R, Nicolai P, Antonelli AR. Imaging in Treatment Planning for Sinonasal Diseases, 2005.2. Yousem DM, Da Motta AC. Head and Neck Imaging Case Review Series, 2nd ed, 2006.

Axial CT images show "railroad track" calcifications (arrows) in the left occipital cortex with ipsilateral enlargement of the choroid plexus (arrowhead) in this patient with a port-wine stain in the left V1 distribution.
Facts

• Also known as encephalotrigeminal angiomatosis
• Sporadic disorder affecting skin and central nervous system
• Defined as capillary malformation of the leptomeninges with or without choroid and facial V1 or V1-V2 involvement (port-wine stain)
• Probably due to embryonic defect of persistent vascular plexus in the neural tube during 6th week of embryonic development
• Port-wine stains can be unilateral or bilateral, most commonly involve V1 distribution but can also be extracranial
• Intracranial involvement always ipsilateral to the port-wine stain of the face, occipital lobe most common

Imaging

• MRI more sensitive than CT in identifying secondary changes due to leptomeningeal capillary malformation
• Cerebral cortical atrophy, compensatory ventricular and choroid plexus enlargement, calvarial hemihypertrophy and superficial gyriform enhancement after gadolinium injection
• "Railroad track" calcification of the cerebral cortex caused by precipitation of calcium likely due to alternation of vascular dynamics of the leptomeningeal malformation

Reference:Gorlin RJ, Cohen MM, Hennekam RCM. Syndromes of the Head and Neck, 4th ed, 2001.Muller-Forell WS. Imaging of Orbital and Visual Pathway Pathology, 2005.

Axial CT image shows multiple small 2-3 mm nodules (arrows) throughout both lungs in a patient with thyroid cancer.
Facts: Miliary Metastasis

• Uncommon form of pulmonary metastasis
• Most commonly due to thyroid cancer, renal cell carcinoma and melanoma

Pulmonary Metastasis in Thyroid Cancer

• Distant metastasis (lung and bone) found in 10-15% of patients with differentiated thyroid cancer
• Lung metastasis is most frequent in young patients with papillary carcinoma, and lungs are almost the only site of distant metastasis in children
• Variables found to be adversely affected survival: extensive metastasis, older age at metastasis, absent I-131 uptake of metastasis, and moderately differentiated follicular cell carcinoma

Our case: thyroid cancer with miliary metastasis
References:1. Biersack HJ, Grunwald F. Thyroid cancer, 2nd ed, 2005.2. Schlumberger MJ. Papillary and follicular thyroid carcinoma. N Eng J Med 1998;338:297-306.

Longitudinal US image of the antecubital fossa shows an echogenic clot in the basilic vein (arrows).
Facts: Superficial Thrombophlebitis

• Also known as superficial venous thrombosis
• Presence of thrombus in the lumen of superficial vein, followed by inflammation of the wall and adjacent tissues
• Variable degree of severity, can be in small venous tributaries but can extend into deep veins or, uncommonly, result in pulmonary embolism
• Related to Virchow's triad
• Prodromes of many systemic diseases (neoplasm, arteriopathy, collagen vascular disease) and syndromes (Trousseau, Mondor disease, Lemierre, Buerger disease)

Imaging

• Color Doppler US provides definitive diagnosis by showing clot, uncompressibility, absence of flow

Reference:Sobreira ML, Yoshida WB, Lastoria S. Superficial thrombophlebitis: epidemiology, physiopathology, diagnosis and treatment. J Vasc Bras 2008;7. Available here.

Fig. 1: Lateral radiograph of the right ankle shows a C sign (yellow dotted line) that extends from the talar dome through the coalition component of the posterior talocalcaneal joint to the sustentaculum tali.
Fig. 2: Coronal reformatted CT image confirms the presence of talocalcaneal coalition (arrows) between the talus (T) and calcaneus (C).
Facts: Tarsal Coalition

• Abnormal bony, cartilaginous or fibrous articulation between two tarsal bones
• Congenital, caused by lack of bony segmentation
• Most common between calcaneus-talus and calcaneus-navicular
• Bilateral in 20% of cases

Imaging

• C sign seen on lateral view when middle facet talocalcaneal coalition is present (as in our case)
• Talar beak is an indirect sign of abnormal talonavicular motion, it is a bony spur from anterior superior aspect of talus
• CT is an excellent method to identify and characterize tarsal coalition

Reference:Chew FS, Bui-Mansfield LT, Kline MJ. Musculoskeletal Imaging, 2003.

Sagittal contrast-enhanced CT image shows a well defined, enhancing mass in the right kidney of a 67-year-old man presenting with hematuria.

Facts: Renal Oncocytoma

• 5% of all adult primary renal epithelial neoplasm in surgical series
• Believed to originate from or differentiate toward type A intercalated cells of the cortical collecting duct
• Men more common than women
• Frequently seen in 7th decade

Imaging Features

• Solitary, well defined mass of renal cortex
• Stellate fibrotic scar can be seen with large tumors
• Spoke-wheel pattern of feeding arteries seen on catheter angiography
• Cannot be differentiated from renal cell carcinoma, and can be associated with RCCs either as hybrid tumors or collision tumors

Our case: Oncocytoma proven by histology. On imaging, this mass cannot be differentiated from RCC and should be investigated as possible RCC until proven otherwise.


Reference:
Prasad SR, Surabhi VR, Menias CO, et al. Benign renal neoplasms in adults: cross-sectional imaging findings. AJR 2008;190:158-164

Follow RiTradiology on Facebook, Twitter or Google Friend Connect
Visit RiT Illuminations to view nice pictures of your colleague