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