6-23-2009 Case 1 - DNET

Alright - the images from top to bottom - CT, FLAIR, GRE/T2*, ADC, DWI, postcon T1, precon T1 and T2

This case represents a Dysembryoplastic Neuroepithelial Tumor (DNET).

1. Benign tumor of neuroepithelial tissue arising from cortical or deep grey matter.

2. Virtually always in patients with refractory partial seizures

3. Majority - younger (in 20's or younger) and male

4. Neurologic deficits are not common

5. temporal (often amygdala/hippocampus) > frontal > parietal; can also be seen in caudate, pons, and cerebellum

6. Cerebellar - present with vertigo, ataxia and gait disturbances

7. Tend to be stable, recurrence is rare but malignant degeneration has occured - therefore long term follow up is recommended.

9. Imaging - similar to low-grade gliomas - can be difficult do differentiate from diffuse astrocytoma, ganglioglioma and oligodendroglioma

10. CT - hypoattenuating mass with occasional calcifications, may see remodeling of inner table; minimal or no mass effect; may resemble a stroke but no evolution over time

11. MR - low signal on T1, high on T2 without surrounding edema; 1/3 enhance and usually peripheral or nodular (i.e. 2/3 don't); if enhancing - may be something more ominous

12. Some have a "soap bubble" appearance; some appear like an enlarged gyrus; can have multicystic appearance

13. Often when cortical - wedge shaped with point toward ventricle

14. FLAIR - mixed hypo/iso with bright rim; GRE - occasionally bleed and can be confused with cavernoma (rare); PD - hyperintense rim; No restricted diffusion

15. HMPAO - hypoperfusion (ictal may have uptake); No uptake on Thallium-201; PET - hypometabolism

16. DDX - Taylor Dysplasia (single Tubersous sclerosis lesion - expand gyrus, nonenhancing, looks like a tuber), Neuorepithelial cyst (nonenhancing single or complex cyst, no bright rim), ganglioglioma (strong enhancement, calcs, cyst), PXA (enhancing nodule adjacent to pia and look for dural tail)

References - http://radiographics.rsnajnls.org/cgi/content/full/21/6/1533 ; statdx.com

Case 2 - Developmental Venous Anomaly

This is a postcon T1 image. It has a "medusa head" appearance of enhancing branching pattern in left frontal lobe. This represents dilated veins in a Developmental Venous Anomaly (DVA). You do not biopsy it.

1. DVA - aka venous vascular malformation or venous angioma
2. Congenital venous anatomical variant in venous drainage of brain.
3. 2% of population and is the most common venous malformation
4. Incidental and don't cause symptoms
5. If symptoms - likely due to a cavernoma which are sometimes seen in conjunction with DVA
6. No surgery as can cause venous infarct
7. 15-30% are associated with another vascular malformation (cavernoma, AVM, capillary telangiectasia) - the most common is a cavernoma
8. Complications - hemorrhage (likely from associated cavernoma), thrombosis of venous malfomation (which leads to venous infarct and can lead to hemorrhage), seizures (mentioned in literature but not much literature to support claim)
9. DVA - fine network of enlarged medullary venules that join to form central venous flow tract that drains to superficial or deep venous system
10. Thought to occur as alternative when normal drainage is not present.
11. CT - not seen on noncon; contrasted CT - large vascular structure in brain parenchyma w/ smaller radiating veins and the large vascular structure draining to superficial or deep venous system
12. MRI - best seen on postcon images - spoke wheel or caput medusa of venules to larger vein that will drain to deep or superficial venous system; intervening brain parenchyma is normal; draining vein usually has straight course
13. If draining vein is near lateral ventricle - usually drains to subependymal vein which is often enlarged
14. Look for other vascular malformations - MRI preferred method

Reference - emedicine.com

Femoral Artery Pseudoaneurysm - Answer Case 1 6/14/2009

This series of images from an abd/pelvis CT demonstrates a hyperdense focus of contrast adjacent to the left common femoral artery with a small neck communicating the two. The patient had a recent cardiac catheterization. This represents a Left common femoral artery pseudoaneurysm.

1. < 5% of arterial access

2. Risks - large catheter, anticoagulation, calcified arteries, HTN, too low a puncture, obesity

3. Physical Exam - pulsatile hematoma at puncture site with a bruit.

4. Ultrasound - rapid diagnosis

5. Small - spontaneously resolve

6. Complication - infection and rupture

7. Tx - surgery, ultrasound guided compression and ultrasound guided thrombin injection

8. US-compression - neck - compress 20-30 min - complications are embolization and thrombosis

9. US-thrombin - thrombin 1000 Units/mL - use 1mL syringe - slow injection into pseudoaneurysm away from the neck; occasionally require more than 1 injection; complication - distal thrombosis from thrombin in system.

Reference - VIR requisites (Kaufman et al)

Pneumotosis - Answer Case 2 6/14/2009

In this image, there is air outlining the wall of large bowel. This reflects pneumotosis intestinalis. The differential for this process is long.

DDx
1. Mesenteric ischemia/infarction.
2. Necrotizing enterocolitis
3. Post anastomosis
4. Intestinal obstruction/volvulus
5. Gastric, duodenal ulcers
6. Perforation of diverticulum
7. Pseudomembranous colitis
8. Post endoscopy and post trauma
9. COPD
10. Steroids
11. Collagen vascular disease
12. Mesenteric abscess
13. Neoplastic bowel wall damage

Therefore, the key is to know the patient's history and clinical scenario. This turned out to be a benign pneumotosis.

reference - http://www.ajronline.org/cgi/content/full/177/6/1319; uhrad; http://radiographics.rsnajnls.org/cgi/content/full/22/5/1093

Colon cancer - Answer Case 3 6/14/2009

The first image from a single contrast water soluble enema demonstrates abrupt cutoff in the descending colon. CT images of the abdomen and pelvis demonstrates descending bowel wall thickening and adjacent lymph nodes consistent with cancer of the colon. Additionally, there is a hypodense lesion in the liver that is irregular and most likely represents a metastasis to the liver.

TAR syndrome Case 3 6/7/2009

So what we see is bilateral absent radii. Absence of the radius is associated with multiple disorders and syndromes. Therefore because both radii are missing suggests a syndrome and the history of thrombocytopenia helps come up with a diagnosis.

TAR syndrome - thrombocytopenia absent radius syndrome.

Differential - Fanconi's Anemia, VACTERL syndrome (Vertebral anomalies, anal atresia, cardiac anamolies, tracheo-esophageal fistula, radial ray anomalies) etc.

Fanconi's - oftentimes has missing thumbs. Short stature, skeletal dysplasias, bone marrow failure, cellular sensitivity and risk for solid tumors and leukemias; needs bone marrow transplant; generally considered to be Auto recessive.

VACTERL - obviously has a lot of other additional problems.

References - http://www.wikipedia.org/ and http://www.medcyclopaedia.com/

Melorheostosis - Case 2 6/7/2009.

What we see is hyperostosis of the cortical bone of the left humerus. It is benign in appearance. No soft tissue mass, no abnormal periosteal reaction or destructive changes. This is most consistent with melorheostosis.

• Classically described as flowing hyperostosis
• Dripping candle wax sign
• Monostotic (single bone), monomelic (single limb), or polyostotic (multiple bones) - but often on a single side of body even when polyostotic
• Often follows a sclerotome
• Irregular thickening of cortical bone (cortical hyperostosis)
• Rare sclerosing bone dysplasia
• Patient's often discovered incidentally when looking for something else
• When symptomatic - often doesn't present till late teens early adulthood - limb stiffness and pain
• Can progress to disability even amputation.
• Can cause muscle contractures, tendon and ligament shortening and soft tissue involvement; growth disturbances (increased width, angulation, unequal limb length)
• Soft tissue - tense, erythematous and shiny skin; anomalous pigmentation; induration and edema of subq tissues; fibrosis; weakness and atrophy of muscles; and linear scleroderma
• Predominately limbs with lower more common than upper extremity
• Also can be seen in skull, facial bones, ribs and vertebrae
• If clavicle, scapula, or pelvis - adjacent limb usually also involved
• Can have endosteal hyperostosis as well
• Can appear like osteopoikilosis - esp in tarsal and carpal areas
• Pelvis and scapula (flat bones) - may appear radiating or localized sclerotic patches
• 25% have soft tissue calc and/or ossification
• Can be associated with linear scleroderma, osteopoikilosis, osteopathia striata, Neurofibromatosis, tuberous sclerosis, hemangiomas
• Have also been associated with glomus tumors and AVMs
• 5 basic imaging patterns - classic, osteoma-like, myositis-ossificans like, osteopathia striata like, mixed

References - http://radiology.rsnajnls.org/cgi/content/full/246/2/638 ; Bone and Joint Imaging (Resnick - i.e. Baby Resnick)

Situs Inversus - Case 1 6/7/2009

Great job - Elisha - you got it within 5 minutes of posting.

So the first image shows dextrocardia. In the original set, the second image shows the stomach bubble on the scout film on the right. In the second image shown here, the stomach is clearly on the right and the ileocecal valve is noted on the left (best seen at the left iliac crest).

This patient has situs inversus.

• Situs - describes position of cardiac atria and viscera
• Situs solitus - normal position
• Situs inversus - mirror image of situs solitus
• Cardiac situs - dictated by atria. (but not the apex - i.e. you can have reversal of left and right atria but apex still points to left)
• Can have situs inversus with cardiac in normal axis (levocardia) or dextrocardia.
• When there is situs inversus - the lungs are often inverted as well - the left has 3 lobes and the right has 2 lobes.
• Dextrocardia may be present but viscera is in the correct position.
• When mirror image is exact - called situs inversus totalis.
• When can't tell - situs ambiguous - heterotaxy - liver may be midline, spleen absent or multiple, atrial morphology unclear, and possibly malrotated bowel.
• 2 primary types of situs ambiguous - asplenia syndrome (right isomerism) and polysplenia syndrome (left isomerism)
• Classic asplenia - double right sidedness - bilateral right atria, absent speen, both lungs have 3 lobes, central liver, aorta and IVC on same side of spine
• Classic polyspenia - double left sidedness - multiple spleens, bilateral left atria, IVC dicontinuity with azygos or hemiazygos continuation, both lobes of lungs have 2 lobes
• All the different varieties are rare - with situs inversus - 0.01%
• Situs inversus totalis - associated with Kartagener syndrome (primary ciliary dyskinesia) (my patient didn't have it).
• Kartagener's - repeated sinus and pulmonary infections - with pulmonary sometimes leading to bronchiectasis (esp lower lobes); 20% of patients with situs inversus; transmitted by Auto Recessive; only 50% of those with Kartagener's have situs inversus; also reduced fertility or infertility is common
• Situs inversus - normal life expectancy (except for those with severe pulmonary complications and those with cardiac anomalies)
• False positive and negative results are usually due to human error with labeling - that is why quality assurance is so important.

Reference - http://www.emedicine.com/ - Dr. Annamaria Wilhelm from Mayo Clinic