Monday, August 13, 2012

Ultrasound Technology Continues to Evolve

The promise of ultrasound has always been in its ability to visualize tissues dynamically without the use of radiation. Today's guest post by Michelle Brunet tells us about the road ahead for ultrasound:

Cardiovascular technicians, diagnostic medical sonographers, radiologic technologists and other healthcare professionals are increasingly incorporating ultrasound as an imaging tool for both diagnosis and treatment. Due to the fact that the equipment is relatively cost effective and it does not rely on radiation, it is becoming more and more important in a range of healthcare departments. Often referred to as the “stethoscope of the future,” Health Imaging’s Editor Lisa Fratt predicts that ultrasound technology, as it continues to become more compact and transportable, will indeed replace the medical tool we are accustomed to seeing around a doctor’s neck.

The advancements have already begun in terms of shrinking or portability, potentially allowing ultrasound machines to be employed in field hospitals and other temporary medical facilities (i.e. in Third World Countries or war settings), but also in point-of-care or beside scenarios. One such example of portability is the development of a wearable ultrasound machine developed upon the encouragement of Master Sergeant Cheryl Vance back in 2002. An instructor at the Sheppard Air Force Base in Texas, Vance began implementing the new form of technology to teach her students how to perform ultrasounds in an efficient manner. Weighing less than four pounds, it consisted of a central processing unit-vest with an attachable probe, a wristband with a mouse and keyboard and an eyepiece displaying the system’s interface.

Recently, the first ultrasound smart phone came out onto the market. In the fall of 2011, Mobisante released the MobiUS SP1. Like other smart phones, it acts as a conventional communications device with typical Internet/e-mail and telephone functions. But once attachable probe is inserted into the device’s USB port it transforms into a mini ultrasound machine. “Ultrasound imaging is safe, effective and can save lives, however more than 70% of the world’s population does not have access to ultrasound because it is expensive and not portable enough,” states Mobisante’s website. The company is hoping its new product (that was approved by the FDA) will allow even the most remote medical clinics to benefit from sonography as a diagnostic and therapeutic tool.

In addition to ultrasound technology becoming more compact and portable, there have also been advancements in performance and capabilities. For example, Philips’ iU22 xMATRIX ultrasound system is capable of switching between two-dimensional and three-dimensional imaging with the click of a button. It also comes equipped with a special transducer that can image two distinct planes at the same time, allowing for a more thorough examination. The Siemens ACUSON S2000 ultrasound system is another example. This particular machine not only performs conventional ultrasounds but also acoustic radiation force impulse (ARFI) imaging to help diagnose masses in the neck, liver, intestinal tract and other areas of the body.

The use of ultrasound is expected to increase in terms of diagnostic and therapeutic methodologies but also in terms of settings, including point-of-care and temporary medical locations. With this in mind, technology will continue to become more sophisticated and portable to meet the growing demand.

Michelle Brunet completed a BSc in biology and environmental studies and a BEd in secondary education. After a short teaching career, she realized writing was her passion and now pursues this full time, contributing to various online and print media, including writing for

Saturday, July 28, 2012

Periostitis Differential Diagnosis

Periostitis is an important finding on a musculoskeletal imaging study. It represents inflammation within the periosteum, a layer of connective tissue which surrounds bone. Various forms exist, which typically reflect the aggressiveness of the underlying process. No good mnemonic here (Roentgen Ray Reader referenced below has one, but it is quite long), but the major categories are:


Physiologic Periostitis
  • Appears around age 3 mos
  • Resolves by 6 mos

Caffey's Disease
  • Infantile cortical hyperostosis
  • Involves mandible
  • Occurs before 6 mos

  • Typically psoriatic or reactive

  • Autosomal dominant disorder 
  • Skin thickening

  • Symmetric 
  • Sclerotic bones

Hypervitaminosis A

Infection (Osteomyelitis)
  • Involucrum - thick irregular new bone that forms from periosteum
  • Sequestra - avascular dead bone from cortical blood supply disruption

  • Can be seen in regular fractures or stress fractures

  • Osteosarcoma (Codman's triangle, sunburst)
  • Ewing's sarcoma (Lamellated, hair-on-end)
  • Chondroblastoma (age<20)

Eosinophilic granuloma

Hypertrophic Pulmonary Osteoarthropathy

Venous stasis
  • Thick, undulating reaction
  • Also see edema, phleboliths
Sunburst reaction of osteosarcoma
Source: AJR


Monday, June 18, 2012

Small Bowel Aneurysmal Dilatation Differential Diagnosis

Small bowel aneurysmal dilatation is a common pattern of disease in the small bowel. It consists of a focal segment of dilated small bowel associated with a mass. The mass is typically circumferential. The mnemonic MALL can be used to recall the common diagnoses.

MMalignant GISTLymphadenopathy absent; obstruction common
AAdenocarcinoma of small bowel
LLymphomaLymphadenopathy present; obstruction uncommon

Left Upper Quadrant Small Jejunal Aneurysmal Dilatation
Source: Radiology Assistant
Metastatic disease can also present with small bowel aneurysmal dilatation. The most common primary is melanoma, followed by lung, breast, and colon cancer. Metastases tend to be multifocal and necrotic.

Friday, June 15, 2012

Radiology Salary: Cautious Optimism?

The American Medical Group Association (AMGA) recently released their 24th annual survey of physician groups. The Annual Medical Group Compensation and Financial Survey was a mixed bag of results. Almost 70% of groups noted an increase in compensation, but the increase was quite small on average: 2.4%.

The question I bet you're wondering though: how did radiology salaries do? All told, not bad, but not spectacular either. The top five specialties were: cardiothoracic surgery ($532,567), interventional cardiology ($504,099), orthopedic surgery ($501,808), interventional radiology ($492,102), and diagnostic radiology ($354,917). However, of the five, interventional radiology had the second highest growth of 2.95%, just behind the interventional cardiologists' 4.13%. The cardiothoracic surgeons actually experienced a decline!

The main figure to watch though is the relative value unit, or RVU. An RVU is the primary measure of a physician's productivity for the majority of participating medical groups. Medicare decides that each procedure is worth a certain number of RVUs. That value is then adjusted by the geographic location / practice environment of the physician. The adjusted RVU is then multiplied by the a dollar conversion factor to arrive at the amount Medicare will re-imburse. Most HMOs in the U.S. use this value as a basis for their repayments. Many physician groups charge up to 300% of this value, and then recoup 60-80% of that amount. For example, take a procedure generally worth one RVU. In Manhattan, this might be adjusted to 2 RVUs. At a conversion factor of $50, Medicare would reimburse $100 for this procedure. The physician group may charge up to $300 to a private insurance company, and could expect to collect roughly $180 to $240 on average.

In radiology, RVUs have been falling, so radiologists have had to work harder (complete more RVUs) to maintain the same salary level. This trend is likely to continue, regardless of whether the Affordable Care Act ("Obamacare") passes in full or in part. Healthcare reform of some shape or another will occur. Radiologists will likely face even further decreases in compensation. The real question is: how will radiologists respond? No one is quite sure yet, other than there will certainly be change.

But going back to the title of the post - what cause is there for optimism about radiology salaries? Well, whatever optimism is there, it is indeed a cautious one. Looking further back in the data, salaries tend to stay flat for a few years, then advance, then flatten again, in a step-wise fashion. Radiology salaries have been fairly flat since 2008, so the field is due for a step up. Whether that happens in 2013 or 2015 though, is anyone's guess. Any future gains are contingent on the broader economy advancing. Til then, keep knocking out those RVUs!

Thursday, June 14, 2012

Gastric Bull's Eye Lesion Differential Diagnosis

While initially described on fluoroscopic studies, the gastric bull's eye lesion differential remains useful to know in the age of MDCT. A quick and dirty mnemonic for this appearance is KLM. 

KKaposi's sarcoma
MMelanoma / Metastases

Hematogenous metastasis from breast cancer
Source: Radiology
GIST and carcinoid tumor can also be included in the differential (but didn't fit the mnemonic so well). Rarely, a gastric lipoma can ulcerate and also give a targetoid appearance.

Wednesday, June 13, 2012

Vertebral Scalloping: Differential Diagnosis #26

Vertebral scalloping is typically caused by dural ectasia. The scalloping typically occurs posteriorly, but rarely may occur anteriorly as well. The mnemonic AMEN can be used to recall the common causes of this finding:

Ankylosing spondylitis

scalloping in acromegaly secondary to hypertrophy
scalloping in achondroplasia due to small spinal canal 

e.g. Morquio's, Hurler's
EEhlers-Danlos syndrome
Sagittal T2-weighted FSE MR Spine of a woman with achrondroplasia
Source: Radiology

Tuesday, June 12, 2012

Ivory Vertebra: Differential Diagnosis #25

Today's Daily Diff is for a homogeneously sclerosed vertebral body, also known as an ivory vertebra. Such sclerosis can occur due to benign or malignant processes. While neurologic involvement is not necessary, the mnemonic LIMP can be used to recall the most common causes:

LLymphomausually Hodgkin's lymphoma
IInfection / idiopathic
MMetastatic disesaepeds: neuroblastoma, medulloblastoma; adults: breast, prostate
PPaget's diseaseblastic phase

Ivory vertebra in Hodgkin's Lymphoma
Source: Radiographics

Monday, June 11, 2012

Focal Liver Mass: Differential Diagnosis #24

A focal liver mass can represent a wide spectrum of pathology, from benign to highly malignant. Being able to distinguish between various diagnoses is critical for establishing an appropriate treatment plan. Unfortunately, there is no ideal modality for doing this - while one can use ultrasound, CT, MR, and nuclear medicine, each has its own limitations. However, knowing some basic features can help narrow the diagnosis.

This post will focus on the appearance of solid hepatic lesions (as opposed to cystic lesions),  as well as their appearance on CT. There's no good mnemonic for this, but try and stay CALM my Fine Happy Friend, if you see such a lesion:

CCavernous hemangiomaMost common benign mass, second most common mass after mets; enhance peripherally first, delayed washout
AAdenomaTypically solitary; seen in women on OCP, men on steroids, or glycogen storage disorders; increased bleeding risk -> surgical removal
LLymphomaMultiple low density nodules; resemble microabscesses in Hodgkin's lymphoma; associated with splenic involvement
MMetastasesMost common malignancy (18:1 vs primary HCC)
hypovascular: colon ca
hypervascular: RCC, thyroid, melanoma, choriocarcinoma
calcified: mucinous adenocarcinoma, osteosarcoma, chondrosarcoma
cystic: mucinous colon ca, lung, carcinoid, melanoma

FFibrolamellar carcinomaLarge mass in a young, healthy person; slow growing; central scar, which may calcify (50%)
HHepatocellular carcinomaArterial hypervascularity; 25% calcify; portal/hepatic vein invasion common
FFocal nodular hyperplasiaCentral scar; contain all normal liver elements; take up sulfur colloid on nuclear scans

Hepatic Adenoma (Portal Venous Phase)
Source: Radiopaedia
To evaluate this lesions, a radiologist may perform a "multi-phase" or "four phase" CT. The phases are as follows:

  1. Non-contrast: prior to contrast injection
  2. Arterial phase: 30 seconds after contrast injection
  3. Portal venous phase:  70 - 90 seconds after injection. 
  4. Delayed phase: 5 - 10 minutes after contrast injection

The texts below have more detailed descriptions of how each lesions appears during each phase.

Wednesday, June 6, 2012

Cystic Hepatic Lesion: Differential Diagnosis #23

The Daily Diff for today relates to a common finding: a low density liver lesion representing a cyst. While the majority of these will be simple, benign cysts, being able to differentiate the other possible entities is worthwhile. Sorry, no mnemonic here, but here are the other possibilities:


Simple hepatic cystmost common (up to 10% of population

Pyogenic cystthickened enhancing wall; gas present (20%); septic patient

Amebic cystsolitary; right lobe; enhancing thickened wall *and* surrounding parenchyma (double-rim target appearance)

Hydatid cystcaused by Echinococcus; thickened wall with calcifications; layering debris (hydatid sand); often multilocular with daughter cysts (spokewheel appearance)

Simple hepatic cyst (they can be huge!)
Source: Radiopaedia

Tuesday, June 5, 2012

Diffuse Increased Liver Attenuation: Differential Diagnosis #22

Today's Daily Diff concerns the curious case of a diffuse hepatic enhancement on CT. Imagine opening a non-contrast CT of the abdomen and pelvis and seeing a chalk-white liver staring back at you. While not a common occurrence, it does occur frequently enough that the following differential is useful to keep in mind. For lack of a mnemonic, the following diagnoses are listed in alphabetical order:


Amiodarone long-term; also causes lung and thyroid toxicity

Glycogen storage disorders



Hemosiderosisaka secondary hemochromatosis; often from long-term blood transfusions

Thorotrast administration (previous)Thorotrast is carcinogenic contrast agent that was used between 1928 and the 1950s, primarily for cerebral angiography; deposits in reticuloendothelial system and is associated with HCC and cholangiocarcinoma

In contrast (ha), diffuse decreased hepatic enhancement on CT is typically caused by diffuse fatty infiltration (hepatic steatosis), or diffuse metastatic involvement.

Diffuse hepatic enhancement on a noncontrast CT
Source: Fundamentals of Body CT

Monday, June 4, 2012

Radiologist Salary Trends In 2012

Many factors play into the ultimate salary that a radiologist earns. As we have discussed before, location, changes to Medicare, and specialization such as interventional radiology can have a significant impact on a radiologist's compensation. No two radiologists will face the same situation. Still, it is instructive to look at the overall trend in radiologist salaries to see where the field as a whole is headed.

To this end, Medscape has put together its Radiologist Compensation Report for 2012 (login required) after surveying over 20,000 practicing physicians in the U.S.. And frankly, the news is not good. Overall, physicians report a decrease of 26% in overall income! 26%! The number seems excessive, but the first paragraph of the report shows the gritty truth:
In 2011, radiologists were the highest-compensated of all specialties surveyed, tied with Orthopedists. Respondents earned a mean income of $315,000 – about 10% less than in Medscape's 2011 survey. Fully one third of radiologists earned $400,000 or more, although this proportion was down from the 2011 survey. Almost one half (48%) earned from $300,000 to about $500,000. About 16% of radiologists earned $100,000 or less -- typically, those working part-time -- up slightly from 1 year ago.
While a 10% drop is better than a 26% drop, that is still a huge drop. If the average radiologist is earning $315,000 this year, that implies a loss of thirty five thousand dollars in just one year. In general, wages show price stickiness, meaning that while they may go up slowly, they rarely go down (this is why in general, people discuss inflation in the economy, but not deflation). For radiologist salaries to be worse than merely 'flat' but to have actually decreased by a large amount is a significant adverse trend. So, what can a radiologist do about this?

Move to a different area of the country
There is significant variation in radiologist salary levels across the U.S. Regionally, the highest compensated area (Great Lakes - $345,000) makes nearly 25% more than the lowest compensated area (Northwest - $275,000). Additionally, within a given area, a radiologist in an underserved area who owns his or her own practice can make significantly more than the average value for the region. As Medscape notes:
For the second year in a row, radiologists in the Great Lakes region (Ohio, Michigan, Indiana, Illinois, Wisconsin, and Minnesota) earned the most, at a mean income of $345,000; however, this represents a decrease since last year. The next-highest earners were physicians in the Southeast, who earned $340,000, followed by physicians in the South Central region, at $337,000. Radiologists in the Northwest earned the least, at $275,000. In the overall physician survey, physicians in the North Central region earned the most.
Clearly though, such a move must factor in one's own preference for an urban vs. rural environment, climate tolerance, and family situation.

Get more training
The statistics cited here are for all radiologists. However, there is significant variation between subspecialties within radiology. An interventional radiologist stands to make 10-20% more than a body imager on average. Also, in general, the more years of experience one has, the more compensation they will receive, especially if they stay in one practice setting and become a partner within the practice.

Why not move here? Your higher salary will cover it.

Change your practice setting
It is a well-known fact that private practice radiologists make significantly more than academic or outpatient center radiologists. While there are some offsetting benefits of being in a practice setting with lower compensation (such as more flexible scheduling, or more vacation), if a radiologist's salary is your main concern, this is an area where you can make a huge impact. Medscape gives you the hard data:
Radiologists in office-based, single-specialty group practices earned the most, with a mean income of $373,000; this value has declined since Medscape's 2011 survey. Radiologists employed by healthcare organizations came in second, at $332,000, followed by those in solo practice, at $331,000. Radiologists working for outpatient clinics and in academic settings earned considerably less.
Overall, while the trend for radiologists and their salaries is adverse in 2012, radiologists still are quite well compensated and can make changes to their careers to help protect their income.

Friday, June 1, 2012

Cloud Considerations For Radiology Practices

The following is a guest post by Steve Deaton of Viztek LLC regarding how the shift to cloud computing will affect Radiology practices.

To better understand the benefits of a cloud-based solution for radiology, consider the ability to have instant access to exams, and the potential benefit of having a specialist always available.  One example would be a car accident that occurs during the early morning hours in a rural area. If the local hospital does not have a radiologist on site at all hours, the staff can call an off-site radiologist and give them access to their cloud-based PACS solution. This allows them to quickly gain information so they can either proceed with immediate treatment or call for transportation to a larger facility.  The diagnostic process can be shortened so that critical patient care can begin quicker.
Cloud-based PACS systems enable practices to grant system access on-the-fly, allowing one physician to quickly communicate with a colleague in order to review time-sensitive images. In the car accident example, such speed and flexibility can quickly help the physician determine if the patient needs immediate treatment or not.
The right Cloud solution puts the practice’s entire workflow into the cloud. Geography and the time of day are removed as constraints, allowing patients to always receive the best level of care. This availability to multiple specialists who can access the system from any internet-enabled device does, of course, raise security concerns. For practices that choose a stand-alone EHR or PACS product that is bundled with a cloud service for web access, the security between the end user and the cloud hosting company needs to be thoroughly reviewed. IT and administrators at the practice should be wary of the partnering cloud provider, and ask detailed questions about security protections, breach responses, and who is ultimately responsible for the security of HIPAA information.

A cloud-based PACS solution means the practice no longer needs to connect to an onsite server or worry about complex setups such as VPNs.  This promotes better image sharing and personal care and also enables the practice to be closer to the longer-term goal of implementing a 100 percent electronic records practice. It’s also the perfect solution for multiple location practices, or those that read images for multiple institutions.
Cloud solutions are the ideal fit for practices that need to manage expenses and can benefit from a pay-per-usage plan that is dynamically scalable to meet growing or falling demand. Digital radiology images that need to be archived for years require a considerable amount of space, and the right cloud provider can offer any amount of needed space at the right price point. Cloud services can reduce capital investments in both ongoing maintenance and server equipment, and related IT staff needed to keep those systems running. Such savings can be substantial, especially over the longer term as the costs of cloud storage continue to decline.

Vendor Review
Truly web-based solutions will utilize an image viewer that is a web-written application and runs on any computer. There is not a need for high-powered diagnostic workstations, or the need for special in-system hardware that is running locally. Placing data on the cloud is not worthwhile if it comes with restrictions in terms of how staff actually access and use the data.
Careful review of prospective PACS, RIS, and EHR vendors is vital to understand the different levels of how solution providers can be “in the cloud.” Some providers who have been in existence for a decade or more often take pride in still running on their original platform. While this might sound like a smart decision that offers continuity and stability, it doesn’t take full advantage of technological progress. When these older heavy systems are put into the cloud, the users are, in essence, remote controlling a large workstation. Internet speeds and the rate of compression are not typically good enough for fluid image adjustment that is required for effective radiology viewing. This causes the familiar problem of image lag, making image manipulation a challenge.
These solutions with older coding might technically operate over the cloud, but they are available with limitations. If all of the tools and functionalities are not available to doctors when reading remotely, then the integration of a cloud system might not be worthwhile. These older solutions may not support mobile devices such as the iPad, which are transforming radiology practices and patient interactions. Practices should explore vendors that not only can meet the demands of today’s mobile and instant-access users, but also look to the future and proactively build systems that are in touch with the latest broader technology developments. Cloud-based PACS and EHR systems have not taken off as quickly as anticipated because it is being put in place on top of older systems that can’t harness all of its benefits. Vendors that offer a 100 percent web-based solution are poised to best take advantage of the cloud and gain widespread adoption among radiology practices.

So what is the solution? Top vendors will completely update their code every few years and start fresh, allowing them to build thin-coded systems that are cloud-friendly and enable all functionalities from any web-enabled PC. Utilizing the latest coding toolsets is the only way to ensure that a Cloud-based solution is a leap forward technologically over an in-house thick-client system.  Otherwise, legacy systems claiming to be on the Cloud do not provide all of the pieces needed to complete the workflow and ensure quality and consistent care. Steve Deaton is a VP of Sales at Viztek LLC, a leading cloud-technology provider.

Thursday, May 31, 2012

Stippled Epiphyses Differential Diagnosis

Today's Daily Diff is about stippled epiphyses. In these cases, the epiphyses appear to have multiple, small, round densities within them. If you have a hard time remembering the diverse causes, don't worry - just take a WHACK at it:

  • maternal use during pregnancy
Hans Zellweger syndrome

  • Hypothyroidism / cretinism is a much more common cause
  • Hans Zellweger aka cerebro-hepato-renal syndrome
  • rare leukodystrophy
  • punctata in patella
  • maternal use during pregnancy
CChondrodysplasia punctata congenita
  • multiple variants exist (ex: Conradi–H√ľnermann syndrome)
  • causes growth problems
Kvitamin K deficiencies
  • Vitamin K reductase deficiency
  • ex: Warfarin use

Admittedly, the mnemonic is a bit of a stretch, but essentially the diagnoses are either due to syndromes or factors that affect vitamin K metabolism.

Stippled epiphyses
Source: Roentgen Ray Reader

Wednesday, May 30, 2012

Neonatal Low Bowel Obstruction Differential Diagnosis

Today's Daily Diff concerns low or large bowel obstruction in the neonate. The clinical differential diagnosis of a neonate with low intestinal obstruction is anorectal malformations, Hirschsprung disease, meconium ileus, functional immaturity of the colon, and distal intestinal atresia. To keep the diagnoses in mind, just remember HAMM:

HHirschsprung disease
  • most common cause
  • caused by lack of ganglion cells in distal colon/rectum
  • colon dilates over time
AAtresia (anal; distal intestinal)
  • can be part of VACTERL syndrome
  • often there is fistula between distal bowel and bladder or perineum
MMeconium ileus
  • associated with cystic fibrosis
  • meconium abnormal
MMeconium plug syndrome
  • aka small left bowel syndrome
  • transient; meconium normal

While other entities can also cause bowel obstruction, the ones listed above cover the majority of the causes. In preterm babies, necrotizing enterocolitis is a major consideration. In an older population, the differential changes for bowel obstruction in children.

Meconium plug syndrome
Source: Radiopaedia

Tuesday, May 29, 2012

Neonatal Lung Disease Differential Diagnosis

The (almost) Daily Diff today is Neonatal lung disease, which contains several entities unique to that age group, as well as many of the diagnoses seen in older children and adults. While a broad differential is listed below, the particular findings of any given case can narrow the differential significantly. Follow up imaging can also help clarify the situation. Unfortunately, I am not aware of an easy mnemonic to help recall these processes. Brute force memory shall have to suffice.

RDSRespiratory distress syndrome
  • preterm
  • ground glass
  • low lung volumes
TTNTransient tachypnea of the newborn 
  • often associated with C-section
  • resolves in 24-48h
MASMeconium aspiration syndrome
  • patchy airspace disease bilaterally
  • increased lung volumes
  • associated with pneumothorax
PNANeonatal pneumonia
  • secondary to group B strep
  • presents with consolidation (round pneumonia - seen in children due to lack of pores of Kohn / canals of Lambert)
PIEPulmonary interstitial emphysema
  • ventilated child
  • lucencies to edge of film
  • associated with pneumothorax
CDHCongenital diaphragmatic hernia
  • gas crossing diaphragm
  • usually presents in postpartum period
  • high mortality rate
  • usually posterior (Bochdalek hernia)
BPFMBronchopulmonary foregut malformation
  • A term that encompasses (see next rows):
  • congenital pulmonary airways malformation 
  • pulmonary sequestration 
  • bronchogenic cyst 
  • neuroenteric cyst 
  • enteric cyst
CPAMCongenital pulmonary airway malformation
  • can fill in and appear consolidative
PSPulmonary sequestration
  • systemic blood supply (aorta)
  • may be cystic
  • intralobar (75%) vs extralobar (has its own pleura - 25%)
BCBronchogenic cyst
  • normal lung tissue without connection to bronchial tree
  • contains fluid (water), variable amounts of proteinaceous material, blood products, and calcium oxalate
  • most common location: mediastinum
NECNeurenteric cyst
  • associated with vertebral anomalies
ECEnteric cyst
  • aka duplication cyst

Each of these entities has a characteristic appearance, which should be studied individually.

Meconium aspiration
Source: Radiopaedia

Monday, May 21, 2012

Unilateral Kidney Enlargement: Differential Diagnosis #18

Various reasons can cause the kidneys to shrink or enlarge, either unilaterally or bilaterally. Having a working differential for each possibility is very helpful. Today's Daily Diff concerns the case of a unilaterally enlarged kidney. The mnemonic device AROMA can be used to recall the common causes of unilateral renal enlargement:

AAcute pyelonephritis
RRenal vein thrombosis
OObstructive uropathyMost be above the bladder/urethra to be unilateral; most common cause
MMiscellaneousex Duplication, hypertrophy, cross-fused ectopia
AArterial obstruction

Severe Acute Pyelonephritis Causing Unilateral Kidney Enlargement
Source: Radiographics

Sunday, May 20, 2012

How To Perform An Intussusception Reduction

What Is An intussusception? 

An intussusception occurs when one part of the bowel becomes entrapped within an adjacent segment of bowel. The bowel is said to have telescoped into itself. The portion of the bowel within the lumen is termed the intussusceptum. The portion of bowel containing the intussusceptum is termed the intussuscipiens. The terminology can be a bit confusing at first, but associate the intusscipiens as the portion of bowel which is the recipient of the intussuscepted bowel segment. The most common location in children is at the ileo-cecal junction.

While an intussusception can occur at any age, it is a common finding in the pediatric age group, especially between ages of 6 months and 2 years. The most common cause is thought to be hyperplastic lymphoid tissue after a preceding viral infection. In less than 15% of cases is there a lead point such as a mass. Intussusception of one of the common causes of small bowel obstruction in children.

Intussusception diagram
Source: Wikipedia

How To Reduce An Intussusception

The classic triad for an intussusception is intermittent abdominal pain, vomiting, and bloody stools (termed currant jelly stools). Diagnosis of an intussusception is typically made using ultrasound. The various imaging characteristics on ultrasound are beyond the scope of this post. Once the diagnosis is made, here is how a reduction can be performed:

  1. Examine the patient. Check for peritoneal signs, as peritonitis is a contra-indication to attempting a reduction.
  2. Order a set of abdominal x-rays to exclude free intraperitoneal gas. 
  3. Consult the pediatrics and pediatric surgery services so that they are aware of the situation.
  4. Prepare the fluoroscopy suite. If using contrast, hang the bag 3 to 5 feet above the table. If using air, make sure a sphygmomanometer is present to measure the pressure and a needle in case of perforation. 
  5. Place the patient prone on the table. Make sure they have been appropriately restrained.
  6. Using a soft-tipped catheter and gel, insert the enema tube into the patient's rectum.
  7. Advance the contrast into the lumen of the bowel until the obstruction is reached. 
  8. Continue giving contrast for three minutes.
  9. If the intussusception is reduced, the ileo-cecal junction should be fully visualized. If it has not been reduced after three minutes, two more attempts can be made.
  10. If the intussusception is not reduced after three attempts, refer the patient to pediatric surgery for operative reduction.
If the intussusception is successfully reduced, the patient should be admitted and observed for 24 to 48 hours for re-intussusception, which can occur 10% of the time.  

Target Sign of Intussuception on Ultrasound
Source: Radiopaedia


Saturday, May 19, 2012

Gracile Bones Differential Diagnosis

Today's Daily Diff concerns gracile bones. This finding is described as a bone which is thinner than normal and slender. The bone may or may not be osteopenic. The causes of gracile bones can be remembered by the mnemonic NIMROD: 

IImmobilization / paralysisMore likely if gracile bone matches area of paralysis
MMuscular dystrophy
RRheumatoid arthritis (juvenile)
OOsteogenesis imperfecta
DDysplasisex. Marfan's syndrome, homocystinuria

A gracile radius is seen in the top image; the bottom is normal.
Source: HighWire

Friday, May 18, 2012

Epiphyseal Cyst: Differential Diagnosis #16

Bone lesions can be differentiated by several features, including age, number, morphology, and location. For cystic lesions located in the epiphysis, the mnemonic CAGGIE is useful to recall the most common possibilities:

CChondroblastomaRare, can have fluid-fluid level
AAneurysmal bone cystCan also have fluid-fluid level
GGiant cell tumorOnly occurs after physeal closure (age>20), fluid-fluid level
GGeodeaka subchondral cyst (benign)
EEosinophilic granuloma

Metastatic disease should also be considered, depending on the clinical context.

Giant Cell Tumor
Source: Radiopaedia

Thursday, May 17, 2012

Cerebral Ring Enhancing Lesions: Differential Diagnosis #15

Today's Daily Diff concerns cerebral ring enhancing lesions. The differential for this finding is fairly broad, and can have a significant impact on patient management. Having a brain metastasis is quite different from a resolving hematoma, no? To keep the various entities in mind, think of the phrase DR MAGIC. This is non-sensical, but if you see such a lesion, perhaps think of Magic Johnson having a Toxoplasma abscess, and um, he's a doctor now for some reason...

DDemyelinating disease
RRadiation necrosisOften incomplete C-shaped ring
MMetastasesThick, nodular wall
AAbscessMarked restriction on DWI; thin wall
GGliomaThick, irregular wall if GBM
IInfarctBasal ganglia

Some people add L to the end of the mnemonic for lymphoma as well. Another entity to keep in mind, especially in certain patient populations, is neurocysticercosis, especially if there are other calcified lesions present.

Source: Radiopaedia

Monday, May 14, 2012

Posterior Fossa Tumors: Differential Diagnosis #14

The Daily Diff for today is posterior fossa tumors in pediatric patients. Since most intracranial tumors in children occur in the posterior fossa, this is a handy differential to keep in your back pocket. The mnemonic BEAM can help you remember the diagnoses:

BBrainstem glioma
EEpendymomaSpreads around structures "toothpaste tumor"
AAstrocytoma (pilocytic)Most common (85%), usually eccentric with a cystic component
MMedulloblastomaMidline, compresses cerebellum

Conversely, of all the intracranial astrocytomas, 60% of them occur in the posterior fossa. All of these tumors (except brainstem glioma) can have "drop metastases" to the spinal cord, so it is important to image the spine if such a mass is encountered.

Hemorrhagic pilocytic astrocytoma
Source: Radiopaedia


Sunday, May 13, 2012

Suprasellar Mass in Adults: Differential Diagnosis #13

Today's Daily Diff is suprasellar masses in adults. The phrase SATCHMOE can be used to recall the diagnoses in this differential. Apparently, 'Satchmo' (without the 'e') was a nickname for jazz great Louis Armstrong. Some purists would omit the 'e' from the mnemonic, especially as eosinophilic granuloma is a form of Langerhans Cell Histiocytosis, which is already covered by the letter 'h'.

SSuprasellar adenomaaka pituitary adenoma; enhances on MR
AAneurysmPulsation artifact on MR

CCraniopharyngiomaArise from Rathke's cleft
Papillary form, age 40s
Typically calcified and cystic
Hypothalamic glioma

Most common pituitary mets: breast, lung
OOptic glioma
EEosinophilic granuloma
Epidermis are DWI+

MR characteristics as well as age can be used to narrow the differential, but those features are beyond the scope of this post... which is a fancy way of saying I am too lazy to look all them up right now, but hopefully will update this at a later time. Or just check out the references below.

Pituitary macroadenoma
Source: Radiopaedia

Saturday, May 12, 2012

Lucent Bone Lesions: Differential Diagnosis #12

Today's Daily Diff concerns lucent bone lesions, which are commonly encountered incidentally when evaluating plain x-rays, especially of long bones. Sometimes, the term lytic is also used to describe these lesions. The word lucent implies a non-aggressive or benign process, while the term lytic implies a more aggressive appearance. However, some radiologists will either use one of these terms exclusively, or use them interchangeably. The table below lists a broad differential for any lucent lesion, but in practice, only two or three entities should be considered for any particular finding when the clinical context is taken into account. The phrase FOG MACHINES (which are apparently a real thing!) can be used to recall these diagnoses. Alternatively, the phrase FEGNOMASHIC can be used, but that's even worse than fog machines, no?

FFibrous dysplasia
GGiant cell tumorAge > 20 after physeal closure

MMetastasesRenal, thyroid, lung
AAneursymal bone cystCan have a fluid-fluid level
Chondromyxoid fibroma

HHyperparathryoidismLesions also called 'brown tumors'
NNonossifying fibromaaka 'fibrous cortical defect' if < 2 cm
EEosinophilic granuloma
EG is part of the Langerhans Cell Histiocytosis spectrum
SSolitary bone cystsaka 'unicameral bone cysts'
Can have the 'fallen fragment sign'

Two major criteria for narrowing the differential down are age, multiple lesions, and location. The entities with multiple lesions are fibrous dysplasia, EG/enchondromas, hyperparathyroidism, metastastes, and infection (FEMHI). The common lesion locations are shown in the diagram below:
Common lucent bone lesion locations
Source: U. of Washington Radiology

* Lucent Lesions of Bone | University of Washington Radiology

Friday, May 11, 2012

Bilateral Lower Lung Disease: Differential Diagnosis #11

The Daily Diff for today is bilateral lower lung disease. Like the previous post on bilateral upper lung disease, several entities commonly cause disease in this pattern. A rough rule of thumb with diseases in the lung is that air rises (ie, endobronchial spread will disproportionately affect the upper lung zones - think TB) and that blood falls (ie, hematogenous spread goes toward the lower lobes). As you'll see below, the rule is quite rough, but is worth keeping in mind. Anyway, keep in mind the phrase BAD LASS when you see bilateral lower lung disease. Not sure what naughty schoolgirls have to do with the lower lung zones, but if it helps you remember...

Desquamative interstital pneumonia
Ex. amiodarone, bleomycin, cyclophosphamide, carmustine
LLymphangitic spread of carcinoma

Clearly, the clinical context will make a big difference in narrowing down the differential to a top diagnosis.

Bleomycin Toxicity
Source: Postgraduate Medical Journal

Thursday, May 10, 2012

Bone Fluid-Fluid Level: Differential Diagnosis #10

A fluid-fluid level is a fairly specific sign for the entities listed below. Being aware of the differential is important since the underlying etiology could be either benign or very malignant. Other features and the clinical context can help narrow down the diagnosis further. The mnemonic here is not the greatest, but to remember the diagnoses, think of the DNA bases: ACGT:

AAneursymal Bone CystBenign; 80% < age 20
GGiant Cell TumorSeen only after physeal closure (age>20)
TTelangiectatic OsteosarcomaMost common location: Femoral metaphysis

The age of the patient is an important factor to consider, as the GCT only occurs after physeal closure.

ABC with fluid-fluid level, best seen on CT
Source: Radiology Assistant

Wednesday, May 9, 2012

Permeative Bone Lesion: Differential Diagnosis #9

While not highly common, a permeative bone lesion is an important finding to note on any study which includes osseous structures. When any bone lesion is encountered, especially a lucent or lytic one, it is important to note the margin, which is also called the zone of transition. If the zone can be easily traced with a pencil, it is called narrow. If  it is difficult to make out where abnormal bone ends and normal bone begins, the zone is called wide. The term permeative implies a lesion with a wide zone of transition and multiple small lytic areas within it. This appearance is considered aggressive until proven otherwise. Common permeative lesions can be recalled by the word POLLEN:

PPermativeHad to make the mnemonic work...
OOsteomyelitisMost common: Staph
LLangerhans Cell HistiocytosisSpectrum: EG (isolated, benign); Hand-Schuller-Christian (systemic, manageable); Letterer-Siwe (poor px)
EEwing's SarcomaA small round blue cell / PNET tumor; called Askin when in chest wall
NNeuroblastoma metsPrimary typically in adrenal, but can be anywhere

As the table above shows, all these entities need medical and/or surgical management.

Ewing sarcome in distal femur
Source: Radiopaedia


Sunday, May 6, 2012

Acro-osteolysis: Differential Diagnosis #8

Acro-osteolysis can be understood by breaking down its components: acro refers to the digits, osteo refers to the bone, and lysis means to break down. In other words, terminal tuft erosions. While not very common, there is a differential for this. I like to think of it as when you see the bony finger tips being PINCH(ed) OF:

PPyknodysostosisassociated with osteosclerosis and Wormian bones
IInjury (thermal)
NNeuropathicdiabetes, leprosy
CCollagen vascular diseasescleroderma, Raynaud's phenomenon
HHyperparathyroidismcalcium, resorption

OOtherProgeria, Polyvinyl chloride exposure
FFamilialHadju-Cheney disease

Hyperparathyroid Hands
Source: Radiopaedia
Note how the terminal tufts appear in the image above. They should be more uniform without the erosions seen in the image above. 

Saturday, May 5, 2012

Osteosclerosis: Differential Diagnosis #7

Osteosclerosis, or general increased density in the skeletal bones, is a relatively rare diagnosis. However, when it occurs, the entities that cause it are important to recognize. One way to recall the various causes for osteosclerosis is the mnemonic Regular Sex Makes Occasional Perversions Much More Pleasurable And Fun (Don't look at me - I didn't make it up):

R - RegularRenal osteodystrophy
S - SexSickle cell disease
M - MakesMyelofibrosis
O - OccasionalOsteopetrosisaka Albers-Schonberg disease
present with fractures, splenomegaly
P - PerversionsPynknodysostosisaka Toulouse-Latrec syndrome
associated with acro-osteolysis and Wormian bones
M - MuchMastocytosis
M - MoreMetastatic carcinomaBreast, prostate, lymphoma/leukemia
P - PleasurablePaget's disease
A - AndAthletes
F - FunFluorosis

Source: Radiopaedia
Other possible causes include osteopoikilosis, osteopathia striata, hypothyroidism, and melorrheostosis. You can thank Brant & Helms for the mnemonic.

Friday, May 4, 2012

Interventional Radiologist Salary 2012

We have previously discussed interventional radiologist salary trends on this site. However, given the changes in the economy since then, seems like high time for an update. Updated from the prior post:

What does someone in interventional radiology (IR) do? 

An interventional radiologist is actually quite different from the typical diagnostic radiologist. Although they undergo the same residency training (diagnostic radiology), an IR physician then receives special fellowship training focused on interventional procedures. This training lasts a minimum of one year, but in some cases may extend to two or three years, for further specialization or research. In IR, the focus is on performing procedures using imaging techniques rather than interpreting studies. An IR specialist can utilize a number of modalities, including ultrasound, CT, and fluoroscopy. Procedures can range from simple line placements to complex procedures involving delivery of therapeutics, long term implantable devices, or embolizations.

Interventional radiologists at work
Interventional Radiologists at work
Source: SIRweb

What are interventional radiology salaries in 2012?

As the economy has stagnated, the job market in radiology has also been affected. Although the effect is not as great in the broader market, the interventional radiology job market is certainly tighter than it was five years ago. Interventional radiologists still do quite well for themselves: the national range of salaries in 2012 is from $166,000 to $474,000 (25 - 75th percentiles). However, an individual interventional radiologist's salary depends on a variety of factors: training, years in practice, location, practice setting, partnership status. Depending on the location, an interventionalist in a high volume practice who is a partner can potentially make over $1,000,000.

Future trends for interventional radiologist salary

With health reform still on the horizon, reimbursement rates may change significantly. As a procedure-based physician speciality, IR is a likely area to see cuts. Given the stagnant economy, the short-term prospects for the field are basically flat. Still, as new treatments are developed, such as interventional oncology and interventional molecular imaging, there are areas for potential growth. Trainees will benefit from staying up-to-date on these rapidly evolving areas and potential future sub-specialties. By bringing a novel skill-set to a practice, a physician makes himself exponentially more valuable to a group, increasing both his likelihood of landing a position, making partner, and receiving higher compensation.

Current fellows looking for a new position as an interventional radiologist will likely have to be willing to take lower salaries initially. They will also likely to be asked to work in other practice areas, such as mammography. However, if this is an area that interests a radiologist, it remains a highly satisfying and highly lucrative career path.

Tuesday, May 1, 2012

Salter-Harris Pediatric Fracture Classification

Fractures in the pediatric population differ from typical fractures due to the possibility of physis (growth plate) involvement. If the physis is fractured, it could lead to growth arrest in that bone. The Salter-Harris classification describes the 5 classes of fractures, with the higher classes being more severe in nature and more likely to cause growth arrest. To remember the Salter-Harris Pediatric Fracture Classification, just remember the name minus the 'e': SALTR

SStraight AcrossType I: Involves physis only
AAboveType II: Fracture involving physis and metaphysis
LLowerType III: Fracture involving physis and epiphysis
TThroughType IV: Fracture involving all 3: physis, metaphysis, epiphysis
RRammedType V: Crush injury of physis

There are 4 more types in the full classification, but these five are most common. Of these five types, Type II is by far the most common (approximately 80%). 

Salter-Harris Fracture Types
Diagram of Salter-Harris Fractures
Source: Radiographics

Monday, April 30, 2012

How To Read A Head CT

A noncontrast CT of the head has become the dominant modality for an initial assessment of intracranial pathology, especially in the setting of trauma. Many approaches to reading a head CT exist, with the method described below simply being one example. As they say, there are many ways to skin a cat. Of course, the real question in my mind is: why is anyone skinning a cat in the first place? Anyway, um, back to head CTs: no matter how you read a study, it is important that you:
  • Cover all the relevant areas of the study
  • Go through your system in a consistent manner
Sounds simple enough, but it is very very important to set up a good system and then go through it each time. On some studies, a major finding may jump out at you and distract from other areas, which may contain even more significant findings. This phenomenon has been termed search satisfaction, which is where you note a finding and therefore stop searching for more. One way to avoid this is to try to make at least two findings on every study, no matter how trivial, just to force yourself to cover the entire study.

Hopefully you are not satisfied with this post... yet. Getting back to head CTs, there are some unique features of the brain that assist in one's reading of this type of study. The main feature is symmetry: the two hemispheres of the cerebrum and cerebellum should generally look the same. Unlike the abdomen or even the chest, symmetry in the head allows for easy comparison across the midline whenever a possible abnormality is questioned. Another helpful feature is that the cranium is a confined space, so if there are masses (or abnormalities with mass effect), neighboring structures will typically be compressed rather than merely pushed out of the way. Practically this means that even small lesions can have a significant impact on the appearance of the brain.

A Systematic Approach

Keeping those general principles in mind, here is one general 10 step approach to assessing a head CT.
  1. Posterior fossa
    Check to see if the cerebellum is symmetric. If the cerebellar fissures are prominent, this may represent volume loss. If the tonsils are low-lying (visible below the foramen magnum), this may represent a normal variation or an Arnold-Chiari malformation.

  2. Ventricles
    Ensure that the four ventricles are in their expected positions and are not enlarged. The lateral ventricles should be symmetric.

  3. Midline structures
    The midline structures should be... midline. Specifically, the septum pellucidum should be exactly in between the lateral ventricles. To check deviation, draw a line from the apex of the inner table of the calvarium anterior to posterior. At the level of the globus pallidus, check for deviation of the septum from the line.

  4. Extra-axial spaces
    Look for any collections between the inner table of the calvarium and the brain parenchyma. Blood, CSF fluid, air, and pus can potentially collect here. For bleeds, biconvex collections represent epidural bleeds; lenticular bleeds represent subdural bleeds and can cross suture lines. Subarachnoid bleeds will line the sulci. The base of the skull is a good place to look for bleeds after trauma due to the sharp edges there.

  5. Brain parenchyma
    Check for symmetry, gray-white differentiation, areas of hyper- or hypo-attenuation, and any architectural distortion.

  6. Orbits
    Check for symmetry, propotosis, lens position and thickness, the optic nerve, artery, and vein. Use soft tissue windows. Make sure no masses are seen behind the globe. This is also a good time to check the lamina papyracea to rule out any fractures.

  7. Paranasal Sinuses
    Look for mucosal thickening or polyp formation. In trauma, fluid and blood can collect in the sinuses.

  8. Mastoid Air Cells
    Check to make sure that fluid is not accumulating in the air cells, especially in the setting of trauma.

  9. Bones
    Fractures can be hard to spot in the skull. The key to identifying an acute fracture is to look for overlying soft tissue swelling, lack of sclerotic margins, and lack of symmetry. Vascular channels are plentiful in the skull and easily confused for a fracture. However, they will have sclerotic margins. Sutures should be symmetric.

  10. Soft Tissues
    Look for soft tissue swelling or masses. Outside of the setting of trauma, the soft tissues should generally be unremarkable.

While this is not a fully comprehensive approach to reading a head CT, it provides a framework for assessing the critical structures. By being systematic and thorough each time, it is highly unlikely that you will miss a significant finding. Review your neuroanatomy thoroughly to help you localize a lesion once you do spot an abnormality. For pediatric patients, the head CT may be preceded by a neonatal head ultrasound, which we will cover in a future post. 

Normal Head CT
Normal Head CT
Source: Wikipedia