History suggests pulmonary embolus
PE is important diagnosis to make because untreated
PE has risk of death due to additional PE, and anticoagulation decreases that risk
On the other hand, if patient doesn’t have PE, anticoagulating patient gives them risk of serious bleeding for no benefit
D-dimer might be considered as a screen, but it is non-specific and in this patient may be elevated just because of recent surgery
Imaging plays big role in making the big decision: anticoagulate or not
What is initial imaging study?

Start with CXR
Even though CXR is insensitive in diagnosis of PE
(most common CXR finding in patient with PE is normal, as on following CXR)
And even though the most common CXR findings in
PE patients are usually nonspecific (pleural effusion, consolidation, atelectasis)
Do the CXR to R/O other causes for symptoms (e.g., pneumothorax), and should have baseline CXR with potentially serious cardiopulmonary disease, in case patient goes bad. Also CXR will often be needed to interpret V/Q scan if done subsequently

Following CXR is on same patient whose
CXR was initially normal, but now with left basilar opacity
This is at least partly due to pleural effusion because of associated meniscus, but effusion is not specific to PE, having many other causes as well

Old gold standard test for PE was catheter pulmonary angiography, now seldom done
It showed PE as filling defect in pulmonary artery otherwise opacified with contrast, as illustrated in the following image (same patient as on preceding CXRs)
Currently contrast-enhanced CT is often used as the next imaging test, if PE is still possible after CXR. CT shows PE in same way that catheter angio had done in the past, but noninvasively

Because key question is anticoagulate or not, some algorithms start with Doppler US of leg veins
If US is positive for DVT, then the key question is answered (patient needs anticoagulation), although there is still some uncertainty as to whether patient had PE, and if so how big
Other problem with US is that about half of patients with PE will have negative leg venous US
US is very useful in pregnant patients (radiation concerns)

Following image shows deep venous thrombosis (common femoral vein)
DVT is recognized on US by lack of full compressibility of deep veins (as illustrated here) and lack of flow on color
Doppler

If patient can’t have contrast-enhanced chest CT
(contrast allergy, renal insufficiency), V/Q
(ventilation/perfusion) scan is older but still commonly used alternative
Ventilation scan done by having patient breathe in radioactive gas (as in following image) or radioactive aerosol
Perfusion scan done by injecting radio-labelled microemboli (macro-agregated albumin in this case) into systemic vein, so that the emboli lodge in the first capillary bed they reach (the lungs if there is no right-to-left shunt)

Perfusion scan is sensitive but nonspecific because other pathologies can cause perfusion defects, such as airway disease (if part of lung is hypoventilated, hypoxia in that area will cause pulmonary arterial constriction, shunting blood away, resulting in perfusion defect)
Ventilation scan allows recognition of airway disease, improving specificity of perfusion scan

Following 2 frames show a V/Q scan with a high probability of
PE
Ventilation scan is normal (symmetrical lung filling on single breath, prompt symmetrical washout without air trapping)
Perfusion scan is picture of pulmonary blood flow frozen in time, allowing images to be taken from multiple angles
(anterior, posterior, both laterals, both posterior obliques)
Note wedge-shaped perfusion defects in lingula of LUL and apical segment of LLL
This is high probability of PE because there are multiple segmental wedge-shaped perfusion defects unmatched by ventilation defects

Because the perfusion scan is so sensitive, V/Q scans are very helpful when normal, effectively ruling out PE
V/Q scans also helpful when resulting in a high-probability reading associated with a high clinical suspicion (chance of PE is 96% -> anticoagulate)
V/Q scans also helpful when resulting in a low-probability reading associated with a low clinical suspicion (chance of PE is 4% -> withhold anticoagulation
Unfortunately most V/Q scans are other than normal, high-high or low-low, in part because ED patients with chest pain and shortness of breath include many who have lung disease which causes abnormal V/Q scans in the absence of PE
V/Q scans are most helpful in patients with no evidence of lung disease on history (non-smoker, no asthma), exam (clear lungs), and CXR (normal lungs). Because 90% of ED patients with ? of PE don’t have PE, if they don’t have lung disease otherwise, their V/Q scan will probably be normal (a powerful result ending the PE W/U).

Usual imaging test to follow CXR in PE W/U is contrast-enhanced chest CT, the new goldstandard, replacing old catheter angiogram
Multi-detector spiral CT on modern scanners results in multi-planar images that are usually diagnostic even in patients who can’t suspend respiration
If PE is not shown on good quality CT, diagnosis has essentially been ruled out, and patient has no increased risk of death from subsequent PE if not anticoagulated

Screening asymptomatic women for early breast CA is meant to decrease deaths from the disease
Topic continues to be very controversial
Am Cancer Society recommends screening with physical exam by trained health pro and mammography (annually starting age 40 in average risk patient)
Others recommend starting mammo later and only every 2 years
Mammo screening probably prevents only about 30% of potential deaths related to breast CA (for most breast CAs, death or survival will occur regardless of whether mammo is done or not)

Screening mammo consists of 2 images, one from above (craniocaudal, to cover medial breast) and one in oblique projection (mediolateral oblique, to cover axillary tail of breast)
Views done with compression, sometimes uncomfortable for patient, but important to decrease motion blurring, decrease necessary radiation dose, and separate possible CA from overlying glandular tissue

Following image is normal CC projection
This breast is composed mostly of fat
(hence the visibility of blood vessels in this case)

Following image is normal MLO projection on different patient
Note that this patient has a dense breast composed mainly of fibroglandular tissue and relatively little fat

One of the main findings of breast CA on mammo is a dominant mass that stands out from the background pattern of normal glandular densities
Following image shows an obvious CA presenting as a mass, easily seen in this breast which is mostly fat
This same mass might be invisible if present in a breast composed mostly of dense fibroglandular tissue

The problem of dense tissue obscuring CA on mammography is why the overall sensitivity of mammo for breast CA detection is no better than 75-80%
Therefore, physical exam is still important as a complement to mammography when screening for breast CA
A suspicious finding on physical exam should not be discounted in the face of a normal mammogram reading, particularly if breast has a lot of normal dense fibroglandular tissue (it may still be a cancer!)
In Connecticut and many other states, breast density must be reported on the mammo dictation

1. Almost Entirely Fat (0-25% dense) –
10% of cases
2. Scattered Fibroglandular Densities (25-
50% dense) – 40% of cases
3. Heterogeneously Dense (50-75% dense) – 40% of cases
4. Extremely Dense (75-100% dense) –
10% of cases

Following are 4 normal CC mammo images from patients representing the 4 classes of breast density
Breast density tends to decrease with age, mostly a reflection of weight gain and more fat deposition
However, young obese patients may have fatty breasts and thin elderly patients may have dense breasts (the fourth image below is from an 80-yr-old patient)

Sensitivity of mammography for breast CA detection is very good (97-98%) in the
“Almost Entirely Fat” breast
However, in the “Extremely Dense” breast the sensitivity is only 3060% (it’s a polar bear in a snowstorm)

In addition to a dominant mass, the other main mammographic sign of breast CA is clustered microcalcifications (this is dystrophic calcification in debris resulting from cellular necrosis, which is often associated with cancers that outgrow their blood supply)
Although benign calcifications of many causes are common on mammo, clustered microcalcifications are suspicious for CA, particularly if they are irregular, poorly defined, linear/branching, and new on comparison with prior imaging

Following mammo image shows malignant clusterd microcalcifications in upper part of image
Note that there are also benign calcifications, including arterial atherosclerotic calcifications in lower part of image

Because mammo findings fall on a continuous spectrum of suspicion
(from normal to obvious CA), essentially all mammo reports will have a final Category reading given at the end of the dictation
The Category reading is required by the FDA (all mammo facilities in
USA must be accredited by FDA)
The Category indicates the level of suspicion, and the recommended F/U
– Category 0 means the W/U is not finished (may need diagnostic mammo with additional mammo views, or US, before final Category reading is given)
– Category 1 and 2 indicate return to routine annual screening
– Category 3 is a low suspicion lesion that usually is re-imaged in 6 months instead of 12
– Category 4 and 5 are suspicious enough that needle biopsy is indicated

Required by FDA
Category
– 0 Incomplete: Need Additional Imaging
Evaluation
– 1
– 2
– 3
Negative
Benign Finding
Probably Benign, Short Interval Follow-
Up Indicated
– 4
– 5
Suspicious for Malignancy (do biopsy)
Highly Suggestive of Malignancy (do biopsy)

Biggest problem with mammo as screening test is its poor sensitivity 75-
80%)
However, its positive predictive value is also poor
Only about 25% of patients recommended to have needle biopsy turn out to have CA

Following diagnostic mammo image done for patient with palpable mass (marked with BB)
The mass is hard to see because of superimposed fibroglandular tissue
This is situation where US has traditionally been used (to characterize mass, felt on exam or seen on mammo, as cyst or solid)

Following image shows that mass on preceding mammo is typical cyst (no internal echoes, sharp back wall, good sound transmission, orientation parallel to skin)
Cyst is much more common cause of breast mass than CA

Because US can detect CAs not visible on mammo (hidden by normal dense tissue), US may be used as supplement to mammo to screen for breast CA
US can see CAs within dense glandular tissue, mammo’s weak point
This practice is not universally accepted because although additional CAs are found on US, it has not been proven that this decreases death from breast CA
However, use of US to screen for CA in patients with mammographically dense breasts is increasing and is in common use in Connecticut
Although by itself US sensitivity for breast CA detection is about the same as mammo, because they pick up different cancers, mammo and US are complementary and together have a higher sensitivity than either one alone

Following image shows a typical CA within glandular tissue
Note that this solid lesion does not look like a cyst (internal echoes, irregular wall, decreased sound transmission, orientation perpendicular to skin)

Compared to mammo and US, MRI has a very high sensitivity for detection of invasive breast CA
Detection relies on contrast (gadolinium) enhancement of breast CA (typically have increased vascularity), so normal dense tissue is not an issue
Because of cost and limited availability MRI not suitable as screening tool for general population, but useful to screen patients at very high risk (based on family history) and for surgical planning in patients with recently diagnosed CA
Following 2 images show enhancing CA in patient with implants and a lot of dense tissue (note enlarged axillary lymph nodes due to mets)