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Slide 4 Note down areas that they had problems. If not covered in current session or planned sessions then will come back to at the end
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Slide 6 Get them to verbalize the silhouette sign? Ask them why we care about it (identification and localization of a pneumonia)
Slide 7 Use this to explain the silhouette sign if you wish (compared to overlayed densities and adjacent densities) Note, all these circles are of the same density, visual illusion that they look different!.
Slide 8 Q. Where might we see the silhouette sign? Students can annotate image directly (2screens/ipad) or point it out with laser pointer
Slide 9 RML pneumoniaQ. Where is the silhouette sign?Q. What lobe is involved? A. Right middle lobe. (Again, student can use a laser pointer or identify on an ipad with annotations)
Slide 10 RML pneumonia – confirming lobe involved
Slide 11 Also in the RML• Why is there no silhouette sign here? A. lateral segment involved and it does
not form border with heart. (Talk about characteristics of consolidation.)Q. What is the straight line on the top of the consolidation? A. It is the pleural
margin of the transverse fissure.
Slide 12 RLL pneumonia.Q. What can we see? A. consolidation lower right lung that obscures or silhouettes lateral right hemidiaphragm.Q. What lobe is therefore involved? A. RLLQ. Can you see lucencies within the consolidated lung? What are they? (Get them to spot air bronchograms.)
Slide 13 Same RLL case, now look at the lateral .Q. Can you trace both diaphragmatic contours? (Get them to see how part of one diaphragm is lost.)• Is this another example of the Silhouette sign? A. Yes.Q. Where? A. Use and integrate what you see on BOTH PA and Lateral.Q. What lobe? A. RLLQ. Do you see tubular branching lucencies? What are they? (Get them to spot air
bronchograms.) What is the underlying pathology A:consolidated lung with air in bronchi
Q. Do they always mean pneumonia? A. No – e.g. BAC, edema, hemorrhage/contusion etc.
Q. Why might you not see them in pneumonia? A. Pus in airways
Slide 14 LLL pneumonia. Case with more challenge.Q. Where is the abnormality? (if the learners falter, prompt them to trace out the diaphragmatic contours.) A. Left diaphragmatic coutour is lost (i.e.Silhouette sign.) Explain that we need to see both hemidiaphs
Slide 15 Same patient, LLL pneumonia.Q. What are the signs here? A. first, the Spine sign (paradoxical abnormal INCREASE in radiodensity from top to bottom of spine; should decrease). Second, only one posterior diaphragm is visible (silhouette sign)
Slide 16 Compare and contrast three spine signs:A: LLL pneumonia (margins of opacity ill-defined and infiltrative)B: LLL atelectasis (linear tissue density shadow + effusion)C: Effusion (sharply defined interface between pleural fluid and visceral pleura surrounding aerated lung)
Slide 17 Compare and contrast LLL and LUL pneumonia.Q. How does the silhouette sign differ in these two patients? (Discuss the silhouette signs that differ between the two.)Q. What does this tell us about where the disease is located? (Talk about the anatomy of lingular and how it comes almost all the way to the left hemidiaphragm.)
Slide 18 LLL (superior segment) and LUL pneumonia same patients
Slide 19 Multilobar pneumonia.Q. Where is the disease?Q. Where are the silhouette signs? A. right heart border (indicates RML) and right hemidiaphragm (indicates RLL )
Slide 20 RML and RLL pneumonia (integrate findings of PA and lateral)
Slide 21 A. Higher risk patients, over 40, smokers, non-resolution of signs and symptoms.Risk of obstructive mass producing post obstructive pneumonia. BAC
Slide 22 Q. What do you think of this case? (they probably will say pneumonia LUL)Q. Can you localize it using the silhouette sign? A. NoQ. Why not? A, No borders are obscured by the lung opacity in this case.Q. How do you suppose this patient presented? A. learners probably will respond with fever, cough, purulent sputum.Q. What if I tell you the patient has been afebrile, but has had several months of profuse watery bronchorrhea? A. (This allows facilitator to emphasize that not all lung opacities are infection, and that need for a broader differential diagnosis is signaled by features not typical for pneumonia. Make point that we MUST integrate the imaging into the patients’ clinical context, because we treat patients, not pictures.Bronchoalveolar carcinoma or adenocarcinoma with bronchoalveolar features
What do they think about this? Where is it? Do we see any silhouette signs? (not). Why not? This one is BAC . You can use this as a launch point to talk a little about BAC presentations if you want.Patient initially treated with antibiotics, no change in CXR
Slide 23 CT from last patient with BAC showing consolidation of LUL
Slide 24 Here is a different patient who is febrile and acutely ill.Q. How is this study different from the prior examples of pneumonia? A. This is a pneumonia with diffuse interstitial and airspace opacities. This pattern is typical for viral disease. This diffuse pattern of hazy increased opacity in lung parenchyma produces a CT pattern called ground glass opacity, that is less dense than the consolidation seen in typical bacterial pneumonia.
Compare with a patient with viral pneumonia, introduce concept of ground glass opacities etc PCP pneumonia
Slide 25 Same patient 6w later for comparison
Slide 26 Q. Two different patients. Which one has viral pneumonia, and which has bacterial pneumonia? A. the image on the left has less dense, ground glass opacities consistent with but not specific for viral pneumonia. Notice that ground glass opacities preserve visible vascular shadows, unlike the denser bacterial infiltrates that obscure adjacent vessels.
Compare and contrast viral pneumonia ground glass opacity on left, bacterial RLL pneumonia on right
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Slide 28 Approximately 150, 40, 300-500, 5-10 cc
Slide 29 Have them discuss the appearance of pleural fluid on different modalities – e.g. CT, US, MRIFluid – mobile, very dense, meniscus, no air bronchograms etc
Margins of free fluid separating parietal and visceral pleura tend to be well defined.
Slide 30 Get students to draw for me what they see in small pleural effusions. Talk about the mensicus versus blunting of a lateral CP angle on the PA with sharp posterior CP in scarring or underventilation
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Slide 32 What is the terminology – named for up or down side? Have them run thro a couple of examples – e.g. which decub in a ?right ptx versus a ?right effusion
Slide 33 How will the fluid look?. Draw on image (this is a normal image turned!)
Slide 34 Q. Which decub is this? A. left lateral – intentionally turned upside down.Q. How do you know?. A. dependent lung is smaller. Fluid level Discuss collapse of dependent lung
Slide 35 Same study correct way up. Show them how it is difficult to see fluid against mediastinum, but also the sheets, lines etc confuse the image
Slide 36 Supine Show how same amount of fluid will vary in appearance depending on patient position. Maybe get them to draw it or me draw it.
Slide 37 Diagram illustrating this
Slide 38 Sag CT of a pleural effusion to demonstrate the same point
Slide 39 So how will a supine pleural effusion look? Draw on image or have them describe
Slide 40 Supine patient with large right pleural effusion.Q: What is the density over the apexA: fluid tracking up
Slide 41 Same patient next day, upright after PICC placement.Q: Do you think the amount of fluid has changed? A: no
Slide 42 With supine pleural effusion, learners should recognize a pattern of hazy diffusely increased radiodensity projecting over the chest with density increasing inferiorly
Slide 43 Q. What is different about this image? A. There is a horizontal line in the left hemithorax.Q. What is the significance of such a line? A. Indicates a hydropneumothorax (i.e. pneumothorax in patient with some fluid collection also) Talk about AFLs
Slide 44 More obvious AFL
Slide 45 Empyema
Q. What do you think might be going on here? A. Complex case with multiple findings to consider. There is an air fluid level. There is air in the pleural space, but it does not flow freely to the apex in this upright (remember the air fluid level) patient. Therefore, at least we have a hydropneumothorax. Restricted passage of air raises question of pleural adhesions laterally. There is abnormal air in the chest wall. There is a therapeutic tube in place in the right chest.
Q. What kind of process could cause the normally slick pleural surfaces to stick together? A.Infection, inflammation
Slide 46 CT of empyema patient
Q. Why is the right chest wall so much thicker than the left? A. Expansion by air. Notice it also is very lucent.Q. What is this round thing in the pleural collection? A. This is the tube placed to drain the empyema.
Slide 47 Massive effusion.Q. What are two causes of white-out of a hemithorax? A. Status post pneumonectomy and massive effusion.Q. What clues help distinguish these? A. Which way has the heart and mediastinal structures shifted?Q. What do you think is going on in this case? A. Learner should identify that heart and mediastinum are shifted to right, and say massive effusion.
Get them to discuss shift. Why this has to be fluid. Patient with chlyothorax after repair of double aortic archNOTE – complete opacification is discussed further in the next case
Slide 48 This section can be done during this session or separately. You can include the calculations or not as you wish
Slide 49 Get them to bring out –Patient factors: age, sex, body habitus, area imaged, genetic factorsTechnical factors: type of exam, area imaged, parameters used, frequency of exams, # of exams, slice thickness, # images, fluoro time etc etc
Slide 50 What we do: Reduce imaging esp in kids, don’t scan, Use US or MRI esp for FU, decrease freq of reimaging
How we do it: shielding, change imaging parameters e.g. low dose, dec area scanned. Etc etc
Slide 51 Get them to order these roughly into 4 groups, by the radiation dose that the patient receives (very low, low, moderate, highest)Very low – wrist, CXR,Low – AXR, mammogram, low dose CT chest, lumbar spine, CT headModerate, UGI, bone scanHighest –CTPA, CT A and P, barium enema, myocardial perfusion, PET FDG
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Slide 54 This can be group exercise with entire class or small groups
Go thro this case study step by step and have them work it out to reinforce concepts. Makes it more real.
Slide 55 Real list of exams that patient received over a 2 month hospitalization. Just to show them how these can add up
Slide 56 Need to print out these summary figures for the students
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Slide 58 Give students a few mins to do the math or do it with them
Slide 59 = 0.21 Sv
Slide 60 Answer = 1.7% (0.21 x 8)(0.5)(2)
Slide 61 Answer = 7%(1.7/24)(100%)
