Rice bodies…

Elderly gentleman came to the ED because he was wandering around the neighborhood.  A bystandard called 911.  He was pleasantly confused, had a mental status consistent with dementia.  The only other pertinent physical exam finding was some erythema, cellulitic appearance to his ankle.  We obtained a tibia and fibula xray looking for gas in the setting of cellulitis and this is what we found:


Rice bodies 2Rice bodies 1

 

The densities in the soft tissue of his legs are “Rice bodies.”  They are sometimes seen in systemic cysticercosis.  These bodies are calcified dead cysts from the organism Taenia Solium.  Typically this tapeworm is found in pork.  Taenia Solium is rare in the U.S., it is more prevalent in underdeveloped countries especially with a diet that has potential to include raw or undercooked pork.  This should also be on your differential with new onset seizures (1).

 

Multiple calcifications 1

 

He also had rice bodies on head CT.  Possibly the cause of his dementia?

Author:  Russell Jones, MD

References

(1) Parasites – Taeniasis.  http://www.cdc.gov/parasites/taeniasis/.  Accessed 1/2015.


Filed under: CT, Head, Leg XR, Non-Trauma, Skin/soft tissue, XR Tagged: Rice Bodies

Student Corner: A Cavitary Lesion

Cavitary lesions in the lungs are gas or fluid filled compartments in an area of pathology, such as a consolidation or a mass. Interestingly, a specific set of pathologies are known to cause this specific finding. Cavitary lesions can be detected on a chest x-ray, as is shown below.

cavitary-mass with IDCavitary masscavitary mass lateral with IDCavitary mass 2

Legend: Red Ellipse–cavity (with margins), Blue Ellipse–air-fluid level

The lesion practically jumps out of the picture on the AP view, but the colored circles are there just to point out the entire area of pathology (blue) and the cavity within (red). The pathology is a bit harder to see on lateral view, but the cavity has an air-fluid level that is easily identified as a vertical line separating a lighter fluid filled portion from an air filled portion. This air-fluid interface is often called a meniscus. You might remember being in chemistry class and measuring water out of tall beakers where the water stuck to the sides of the glass creating a concave meniscus. The surface tension of water allows it to stick to both itself and surrounding surfaces. If you look close enough, you’ll notice that the air-fluid level in the image above, best visualized in the AP view, has a slightly concave shape because the liquid at the bottom is sticking to the solid sides of the cavity.

The underlying pathophysiology is an interesting concept to understand when discussing cavitary lesions. A cavity can form in lung tissue for various reasons, but infection is the major underlying cause. Abscesses are localized collections of pathogens, fluid and immune system components that are walled off from the surrounding tissue, therefore creating a fluid-filled cavity. Tuberculosis is a disease process that involves caseous necrosis, which results in coagulation of cell proteins and liquefaction of cellular components. Eventually, the liquid portion drains out through the lymph system or through the bronchi, leaving air pockets behind. Necrotizing pneumonia and non-infectious processes such as ischemia and neoplasm can also cause a similar picture. Rheumatologic diseases such as granulomatosis with polyangitis and sarcoidosis also cause cavitary lesions by causing localized inflammation, which in turn leads to an area of increased mass, which then in turn can cavitate once the inflammatory reaction recruits fluid to the area. In other words, most of these processes, even if they aren’t inherently related to one another, all converge on the same mechanism of causing a localized area of inflammation.

With such a wide array of categories to choose from, it is perhaps more important than usual to contextualize the radiographic image with information about the patient.

This particular patient is a 30 year old male who presents with a cough.  He has been traveling around the world to multiple continents including Sub-Saharan Africa.  The extensive travel history, including to continents with rare infectious diseases leaves infection at the top of the differential. Things like Staphylococcal pneumonia, fungal infections and even amebiasis are possible because of the patient’s travel history. For a complete list of the infectious causes of a cavitary lesion, check the first two references at the bottom of the page.

References/resources:

Gadkowski LB, Stout JE. Cavitary Pulmonary Disease. Clinical Microbiology Reviews 2008;21(2):305-333. doi:10.1128/CMR.00060-07. (LINK)

Ryu, Jay H. et al. Cystic and Cavitary Lung Diseases: Focal and Diffuse. Mayo Clinic Proceedings , Volume 78 , Issue 6 , 744 – 752. (LINK)

Good pathologic image of caseous necrosis with resulting cavitation

Image Contributor:  James Luz, MD

Author:  Jaymin Patel


Filed under: Chest XR, Non-Trauma, Respiratory, XR Tagged: Pneumonia

What valve has been replaced?

Here is a patient with a cardiac valve…he did not know which valve was replaced.  Which one is it?

Valve AP Valve Lat

RadDaily.com helps with this dilemma:

http://www.raddaily.com/whitepaperarticle.php?articleTitle=Cardiac+Valves:+Assessment+and+Identification

If we apply the rules from RadDaily.com to our patient, it appears he has an aortic valve:

Valve Lat EditedValve Lat

Valve AP editValve AP

AV = Aortic Valve*

TV = Tricuspid Valve*

MV = Mitral Valve*

PV = Pulmonic Valve*

*These are anticipated locations.  The locations could be altered if the patient has anatomic variations such as chamber enlargement, cardiac rotation, etc.

RadDaily also has additional information using flow directional clues from the shape of the valves.  Check it out!

Author:  Russell Jones, MD


Filed under: Cardiac, Chest XR, Devices, Non-Trauma, XR Tagged: Heart Valves

Student Corner: How to Read a Head CT

Head imaging is both a crucial tool in acute medical care, particularly in the setting of trauma, and a very daunting aspect of learning radiology for students. However, as is the case with many clinical skills, a “systematic approach” goes a long way in helping ease the initial challenge of learning how to read and understand head imaging. For this post, we will focus primarily on head CTs because they are more commonly used in emergency departments due to the fact that they are fast, readily available, and highly informative in trauma.

A head CT presents a few unique challenges. The anatomy is subtle and nuanced. The area has numerous pathological possibilities. The pathologies themselves can change over short time periods. There are different types of fluids and soft tissues. In short, the brain is kind of scary.

But, the best way to get over your fears is to face them. And therefore the best way to look at a head CT is to look at it with a plan. The plan in this case is a (surprise!) mnemonic: Blood Can Be Very Bad” and it is detailed below.

Blood

Hemorrhage of blood into the cranial vault is one of the easier things to identify on head CT. Acute hemorrhage is hyperdense (bright) and becomes hypodense (dark) as time goes on. Two of the most commonly encountered types are subdural hematoma and epidural hematoma. Subdural hematomas arise from the bridging veins and are seen as crescent shaped anomalies at the periphery of the cranial vault. Epidural hematomas arise from the middle meningeal artery and are lentiform or lens-shaped because their expansion in limited by suture lines (the dura attaches to the cranium at the suture lines).

Other types of hemorrhage include:

Interparenchymal hemorrhage–can either be traumatic or non-traumatic, occur in the brain matter itself

Interventricular hemorrhage–seen as hyperdense fluid in the ventricles, which are usually black because they are filled with hypodense CSF, can be secondary to other types of hemorrhage or trauma

Subarachnoid hemorrhage–most often due to aneurysm rupture and presents with very acute headache (thunderclap headache), seen as fluid in the subarachnoid spaces.  Subarachnoid is also very common in trauma.

The image below is an example of subdural hemorrhage. The left side of the cranial vault is filled with hyperdense fluid, indicating that this process is acute. Also, note the midline shift that occurs, which is shown by the compression of the ventricles more so on the patient’s left than the right and the movement of brain tissue over to the patient’s right. There is also some extracranial soft tissue swelling on the patient’s left, indicating a possible traumatic process. Extracranial soft tissue swelling can help guide your eyes, so to speak, when looking for pathology.

SDH with midline shift 1

Cisterns

Cisterns are spaces between the pia and subarachnoid meningeal layers that can be filled with CSF. There are numerous cisterns that can be identified on a head CT, but the major ones that you should be familiar with are outlined here on Radiopaedia.

These cisterns can be used to identify increased intracranial pressure or subarachnoid hemorrhage (detailed above). In the setting of increased ICP, these spaces become compressed. In subarachnoid hemorrhage, there is hyperdense blood inside them instead of hypodense CSF.

Brain

The brain tissue itself is composed primarily of grey matter and white matter. You can see the difference between these two types of tissue because grey matter is more dense and therefore appears more bright on CT. The gyri and sulci can also be visualized and they should be generally symmetric.

The pathologies that can be identified in the brain parenchyma include:

Abscesses–areas of focal infection from bacteria or fungi, often seen as round areas of ring-enhancing hypodensity with associated edema; midline shift is also a possible finding depending on the size of the lesion.

Tumors–areas of abnormal growth whose particular appearance is variable depending on type and location; midline shift is also a possible finding depending on the size of the lesion; particularly well visualized on contrast-enhanced CT because the blood-brain barrier is disrupted during tumor development and growth, which allows the contrast to leak into the tumor and make it bright.

Infarction–when the blood supply is cut off from brain tissue it causes swelling (which can result in midline shift) and the area becomes hypodense and loses grey-white differentiation.

The CT image below shows a few interesting things. The most obvious one is the multiple hyperdensities seen in the brain matter. These lesions are most likely calcified and can represent anything from inflammatory reactions to infections to tumors. The other finding is that the gyri are thin and the space between them is much more evident than normal, which represents atrophy of the brain due to old age, dementia or both.

Multiple calcifications 1

Ventricles

For the sake of brevity, we will not go over the normal anatomy of the ventricular system. The key radiological aspects of the ventricles in the brain are their size and symmetry. They are filled with hypodense CSF and their size can increase due to hydrocephalus, or increased accumulation of CSF. Hydrocephalus is either communicating (obstruction at the arachnoid granulations which function to resorb the CSF) or non-communicating (obstruction at any point in the ventricular system, usually at the foramina which connect the different ventricles.

Symmetry comes into play when there is a mass lesion on one side of the brain, which can cause compression of one of the lateral ventricles with or without midline shift.

One other aspect to keep in mind is that enlargement of the ventricles can be due to atrophy of the brain parenchyma itself, a condition known as “hydrocephalus ex-vacuo”. Therefore if the ventricles do indeed look large, the brain parenchyma should be examined, paying close attention to signs of atrophy. If the ventricles are enlarged and the brain matter looks compressed and the sulci lose their normal wavy pattern (a process called “effacement”), hydrocephalus is more likely.

Bone

Skull fractures are a common finding in head trauma and they can be seen on head CT. Fractures are seen as dark lines in the usually bright bones. They must be distinguished from suture lines, which are seen as symmetrical wavy lines across bones. Basilar skull fractures are harder to identify, as the base of the skull has multiple different areas and bones. Radiopaedia has a great example of this here.

One of the things to keep in mind with fractures of the skull is to follow the fracture lines. Fractures often cross into different bones and, especially when looking at the base of the skull, fracture lines can extend much further than you would expect.

The image below shows a painfully obvious frontal sinus fracture, where the the bone fragments actually protrudes back into the brain tissue itself. This view is slightly different from the other images on this post because it is shown in the “bone window”, which is a type of image processing that highlights the hyperdense bones on a CT. It makes fractures much easier to identify (although I’m not quite sure you needed the special window to see this one).

CT head trauma2

 

 

—–

All in all, it is also helpful to keep a few other concepts in mind.

Symmetry is key in identifying pathologies, since irregularities in the tissues or fluids are almost never symmetrical.

Utilize the bone window, even if you don’t suspect a fracture.

Soft tissue swelling on the outside of the cranial cavity itself can help you identify the principal point of impact in traumatic injuries and help you find underlying pathologies.

Always use a systematic approach because otherwise it is pretty easy to miss subtle pathology.

Hope this was helpful to you all, but don’t take this as a complete manual of how to read a head CT. Always corroborate your reads with a more experienced physician and always attempt to read the image on your own before looking at any published interpretations. Ask other people about tips and tricks that they might have. And finally, read as many as you can!

Author: Jaymin Patel

References/Resources:

University of Virginia tutorialhttp://www.med-ed.virginia.edu/courses/rad/headct/

Elsevier Health, How to Read a CT Scan- http://www.elsevierhealth.com.au/media/us/samplechapters/9781416028727/Chapter%2069.pdf

Agrawal A. How to read a CT scan of a patient with traumatic brain injury?. NMJ. 2013; 2(1): 02-11.


Filed under: CT, Head, Head, How To's, Student Corner, Trauma Tagged: blood can be very bad, bone window, computed tomography, ct, Head, head ct, head trauma, how to, midline shift, student corner

Massive splenomegaly…Answer

Last week I showed you this CT showing massive splenomegaly:

Splenomegally + Masses

 

The abdominal CT above shows massive splenomegaly with various areas of hypo attenuation throughout the spleen.  Massive splenomegaly is a term used when the volume of the spleen is expected or calculated to be >1000 grams or clinically extends well into the left lower quadrant or past midline.

A short differential diagnosis for massive splenomegaly includes (1):

  • Malaria
  • Myelofibrosis
  • Leukemia (especially CML)
  • Polycythemia Vera
  • Lymphoma (several types)
  • Lieshmaniasis
  • Thalessemia

The ill-defined hypo attenuated lesions in this spleen raise a high concern for lymphoma.

Author:  Russell Jones, MD

References

1.  Luo EJ, Levitt L.  Massive Splenomegaly.  Hospital Physician, 5/2008.  Accessed 11/2014 at: http://www.turner-white.com/memberfile.php?PubCode=hp_may08_spelnomegaly.pdf


Filed under: Abdomen/Pelvis, Abdomen/Pelvis, CT, Non-Trauma