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2025 Aquifer-Radiology Actual Exam
What are cases in which spine sign occur? ANSWER Spine sign - vertebral bodies should be relative lucent (black) above the diaphragm on lateral projection. It’s actually when a silhouette is LOST that we say it’s a "silhouette sign" What is spine sign? ANSWER When the combined density of the vertebrae and some source of fluid/consolidation make the vertebrae look denser [just like ice over water accentuates the ice appearing like they have increased density even though they still the same ice]
- Lateral x-ray goes through spine + pneumonia and vertebra will appear whiter (fewer x-rays reach detector since some are absorbed in the pneumonia)
- Helpful sign for detection of lower lobe pneumonia. - - Very useful for detecting LLL pneumonia behind the heart.
- If vertebral bodies appear denser (whiter) above the level of diaphragm, and part of one of the diaphragms is obscured → spine sign → sign of lower lobe pneumonia
- There are other causes for the spine to appear whiter (such as a blastic bone metastasis). What is the lingula aligned with? ANSWER The left heart border (this is more visible in the lateral view x-ray) What are air bronchograms? ANSWER Air-filled bronchi within an area of consolidation. These are frequently seen in pneumonia, but can also be seen in some tumors and other lung abnormalities More common in alveolar disease Air bronchogram ≠ pneumonia Can be seen in lung cancer (adenocarcinoma with bronchiolalveolar pattern) Can be seen in lymphoma of the lung Seen in:
A. Pneumonia C. Pulmonary edema D. Pulmonary hemorrhage Window vs. Reconstruction on CT? ANSWER Reconstructions - processing of the raw CT data allows for better resolution of the structures [higher resolution and higher contrast Reconstruction can be done in 3D (ortho) or in a linear way too (vascular) What is the total range of Hounsfield units available? ANSWER - 1000 (air) to +1000 (metal) [so range is 2000] What does a typical computer display show for greyscale range? ANSWER What can the human eye actually distinguish? ANSWER 256shades (that means each shade of grey covers ~8HU) The can only distinguish 17 shades of grey What is a good way to check diaphragm flattening? ANSWER Look at the lateral film Diaphragm will be flat like you can set a ruler down on the edge What can a poor inspiration/hypoinflation appear like? ANSWER consolidation or PNA How to look at the lung fields? ANSWER Sweep or a zig zag down the lung field (both in PA and lateral views) look for focal, diffuse, BL asymmetrical, interstitial/vasc markings, lucencies (cavity/bullae/PTX), compare upper and lower and L/R zones Middle lower zones Which hilum should always appear higher on the radiograph? ANSWER The LEFT sided hilum should be higher - if it’s not it’s pathological
What is the silhouette sign? ANSWER The visual interface between structures of different density. E. ARDS Which patients w/ PNA should have a follow up xray? ANSWER All patients
40 years History of recurrent pneumonia Current/former smokers Patients whose symptoms do not resolve What is the MC cause of solitary pulmonary nodules on CT scan? ANSWER Well-differentiated adenocarcinoma (formerly known as bronchioalveolar carcinoma (BAC)) Common in smokers AND non-smokers (esp females) True/False - mycoplasma PNA can cause Kerley B lines as seen in CHF? ANSWER What are Kerley B lines? ANSWER TRUE Kerley B lines (septal lines) represent thickening of interlobular SEPTA Note that sometimes Kerley B lines can be distinguished because they extend and touch the pleura What are ground glass opacities? ANSWER "Ground glass" is a radiology descriptive term (used in both chest radiographs and CT imaging) to indicate that blood vessels are not obscured, as would be the case in alveolar lung opacities. Compare ground glass opacities vs. consolidation opacities Ground Glass: Blood vessels are not obscured on CT. "Smoke-like" opacity on CT that does not obscure blood vessels Descriptive term (usually primarily used on CT imaging). May represent either interstitial or alveolar disease. Some diseases (like PJP infection in HIV
infection, early edema, etc.), often have "ground glass" opacities early in the disease process. Consolidation: BLOOD VESSELS are obscured on CT and air bronchograms are more common. What dosage of radiation in x-rays is 1 CT scan worth? ANSWER 150 x-rays worth of radiation per CT scan (ON AVERAGE) Some scans use more or less however depending on the application - for example PE scan = 400CXRs Abdominal Scan = 750CXRs V/Q scan = 800CXRs What is a hydropneumothorax? ANSWER How much fluid is needed to be able to distinguish this? ANSWER AN AIR-FLUID LEVEL (a horizontal edge between air and fluid) You will only see air-fluid levels on upright or decubitus studies It takes at least 150 cc of fluid to see it on a PA CXR; 50 cc on a lateral; and about 5 to 10 cc on a CT scan. What is a pleural pseudotumor? ANSWER A pleural "pseudotumor" is a loculated or localized collection of fluid in a major (oblique) fissure or right minor (horizontal) fissure and it can be mistaken for mass in the lung (hence the name "pseudotumor"). They are more common in pleural effusions associated with CHF for reasons that are not well explained. The abnormality is in the pleural space and NOT in the lung. What is deep sulcus sign? ANSWER Deep sulcus sign is the sign of a pneumothorax on a supine chest radiograph (look for costophrenic angle thats pushing DOWN with a very sharp looking sulcus) What is continuous hemidiaphragm sign? ANSWER Continuous hemidiaphragm sign is a sign of a pneumomediastinum on a chest radiograph
At what diameter does a pulmonary "nodule" become a "mass"? ANSWER
3cm is called a "mass" What lung nodule characteristics should be assessed to guide management? ANSWER What about patient factors that influence risk for cancer? ANSWER Nodule factors: Size of the nodule (malignancy increases over 1 cm) Edge (smooth, lobulated, spiculated, ill-defined) Presence and pattern of calcification (some patterns are benign) Growth (any change from prior images? ANSWER) - fast growth is concerning Patient factors: History of lung fibrosis, asbestosis, etc. Age (over 40 the risk of malignancy increases) Smoking history (greatly increases risk a nodule is malignant) Travel history and history of living in areas where granulomatous disease is endemic (over 40% of people have nodules in some endemic histoplasmosis regions) History of other malignant diseases (could it be a metastasis? ANSWER) What is the management strategy for <4mm nodules with no risk factors? ANSWER What if there are risk factors (smoking)? ANSWER If <4mm and no risk factors - no followup needed If <4mm and risk factors - followup at 12 months (no imaging rec yet however) How is the management of a nodule >8mm handled? ANSWER RISK stratify first Low risk (<5%) of malignancy - serial low dose CT 3,6,9,12 months Intermediate risk (5-60% chance) - FDG PET/CT - if neg then serial CTs to track it, but if positive then get biopsy
High risk (>60% risk) - straight to biopsy or surgical resection What is a ground glass NODULE? ANSWER Opacity that does not obscure the underlying lung parenchyma or blood vessels
How much does low dose lung CA screening lower mortality in the smoking population? ANSWER Mortality decreased by 20% Medicare requires that: (for CT cost coverage) Ages 55- 77 Smoked at least 30 years (and if they quit it was w/in the last 15yr but no longer) What fraction of a normal CT scan is a "low dose" scan? ANSWER 1/5 - 1/8 of the normal radiation dosage What kinds of cancer does low dose CT typically detect? ANSWER Adenocarcinomas - usually as solitary nodules Screening is not as good for squamous cell tumors of the central airways. It is not at all useful for screening for small cell lung cancers, which grow very quickly. What is the next step when a SPN (solitary pulmonary nodule) is found on CXR? ANSWER Should you go straight to biopsy? ANSWER You CANT characterize it from this low resolution GET A CT - then characterize the nodule to guide further management steps DONT go straight to biopsy b/c it might be an AVM or vascular and you would cause an emergency Should CT ordered for a SPN (nodule) on CXR be with contrast or without? ANSWER This scan can be done without contrast, which helps us assess if the nodule is calcified. IV contrast MAY be necessary in larger tumor masses, particularly if there is concern for hilar or mediastinal nodal involvement. Cost of a non-contrast CT of the chest? ANSWER ~$ Give a quick description of the reimbursement practices for imaging studies? ANSWER Reimbursement:
Have to assess how much lung function they have to start w/ to decide which is even possible. What are the contraindications to CT guided (percutaneous) lung biopsy? ANSWER Relative contraindications: Bleeding diathesis Pulmonary hypertension Severe emphysema Ventilated patient Central lesions What imaging studies are appropriate to order for a suspected (non-tension) pneumothorax? ANSWER 1. An erect expiratory CXR plus
- A lateral decubitus laying on the OPPOSITE side of the suspected PTX (make the lung fall away and show the gap) What determines the treatment for a small PTX? ANSWER Depends on the patient's clinical status (symptoms, pulse oximeter, etc.) If they are not symptomatic or have minimal symptoms:
- Watch and wait
- Repeat imaging in about four hours prior to discharge from the same day procedure unit
- If the PTX is unchanged or smaller, discharge with instructions to return immediately if symptoms worsen and repeat imaging a day or two after discharge. What is the treatment for a Tension PTX? ANSWER large-bore needle into the second left interspace in the mid-clavicular line Most common post-op findings on CXR for pts who underwent thoracic and abdominal surgeries? ANSWER Etiology Lower lobe atelectasis (most commonly) Lower lobe pneumonia Pleural effusion. Differential diagnosis for complete opacification of a HEMIthorax? ANSWER Must consider the mechanisms that could cause this including:
Loss of lung volume Shift of heart and mediastinum to side of complete opacity Mechanism causing mass/fluid in hemithoriax Shift of heart and mediastinum away from side of complete opacity Etiology often difficult to determine by chest radiograph
- Pneumonectomy (lung was removed sugically)
- Huge pleural effusion
- Total Lung PNA
- Large Mass (not ARDS because that would be bilateral? ANSWER) Compare hydropneumothorax vs. simple pleural effusion Air-fluid level in hydropneumothorax appears as a horizontal line, rather than the usual meniscus seen with an isolated simple pleural effusion [meniscus occurs with pleural effusion because there is negative pressure in the pleural space and the fluid tracks up the side] CXR signs of atelectasis Volume loss in the affected hemithorax (smaller overall) Tracheal deviation to the affected side Hemidiaphragm elevation (but can still be seen) Hazy opacity over the affected hemithorax ('ground glass' - still can see the vascular markings of the lobe through it) Loss of heart border Large white mass pushing everything AWAY from it on CXR? ANSWER Huge pleural effusion (missing space pulls trachea and heart TOWARD it) What does an initial "trauma series" group of x-rays include? ANSWER Initial radiographic trauma series:
- AP (supine) CHEST on a trauma board (remember your patient would need to stand for an erect PA)
- AP supine PELVIS radiograph
sulcus inferiorly, while producing increased lucency of that sulcus (deep sulcus sign)
- Sign of PTX on supine CXR
- SWA: right sulcus - not as low as L costophrenic sulcus Can you see a small PTX on a SUPINE CXR? ANSWER Golden rule: If you can see a pneumothorax at all on a supine chest radiograph, it is at least moderate. How can you tell if the white line of a PTX is in fact a PTX and not a skin fold? ANSWER The visceral pleura line of a PTX will have dark ON EITHER SIDE of the line (where skin will just be light on one side and dark on the other). Signs that at PTX is a tension PTX? ANSWER Marked mediastinal shift away from the side of the pneumothorax Marked diaphragmatic depression on side of pneumothorax The lung is often completely collapsed Although going down too low may push an ETT tube into one of the R or L main bronchi - what is the risk of not going far enough? ANSWER If an ETT is too high (e.g. tip above the clavicles), the balloon inflation may cause damage to the vocal cords or leak air. Where is the proper place for the tip of a FEEDING tube to reside? ANSWER Why? ANSWER What about regular NG or OG tube? ANSWER 3rd portion of the duodenum or duodenal-jejunal junction. This is to prevent reflux and aspiration of the NG feed. Tips of regular nasogastric (NG) or orogastric (OG) tubes should be in the stomach In what conditions should you order "rib films"? ANSWER Children with suspected child abuse (nonaccidental trauma) and possible posterior rib fractures on the screening CXR Patients with cancer and abnormalities on bone scans suspected to be benign fractures versus metastases
When are rib fractures MOST visible on xray? ANSWER AFTER they have begun to heal and become more opaque How does pneumomediastinum appear? ANSWER A pneumomediastinum appears as streaky black lucencies in the mediastinum, and will usually appear as a black line along the heart border and aorta. You may see air in the subcutaneous tissues. Causes of pneumoediastinum? ANSWER Common causes of pneumomediastinum
- Spontaneous - usually young, fit, skinny men
- Related to high inspiratory or expiratory pressures - asthma, intubated patients (often with high PEEP settings such as acute respiratory distress syndrome)
- Secondary to a pneumothorax or pneumoperitoneum (e.g. laparoscopy)
- Secondary to esophageal perforation (vomiting, instrumentation, tumor)
- Traumatic from a tracheal or bronchial rupture
- Tuba playing
- Freebasing cocaine Radiographic signs of COPD? ANSWER Other radiographic signs of COPD:
- Hyperlucency of the lungs due to destruction of the capillary bed and lung parenchyma, especially in emphysema
- Narrowing of the cardiomediastinal silhouette secondary to hyperinflated lungs, especially in emphysema
- Bullae which are often apical chest radiograph corresponding CT
- Coarse and distorted bronchovascular and interstitial markings, more common in chronic bronchitis than emphysema
- Peribronchial cuffing, more common in chronic bronchitis as the walls of the bronchi are thickened (related to hypertrophy of mucus glands and inflammation)
- "Saber sheath" trachea due to compression of the mediastinum and trachea; Complications of COPD that can be seen on CXR? ANSWER Signs of complications of COPD: Cardiomegaly - especially right-sided chambers (can result in cor pulmonale)
A non-contrast CT will NOT reveal an intimal flap!!! What is the next step to look for an aortic dissection if your patient has contraindication to receiving contrast.? ANSWER 1. Order an MRI with gadolinium
- If they have GFR <30 do the MRI w/out gadolinium
- If they ALSO have contraindication to MRI then do TEE (only useful for ascending aorta) What are the contraindications to MRI scanning? ANSWER - Intraorbital metallic foreign bodies. (Do an orbital x-ray if history is suggestive or patient is occupationally at risk.)
- Cardiac pacemakers and ICD devices.
- Temporary breast tissue expanders. (Prior to reconstructive breast surgery.)
- Epidural devices such as spinal stimulators.
- Severe claustrophobia. (Requires sedation, usually with p.o. Valium. Sedated patients cannot drive after the exam and will need a ride home.)
- Ferromagnetic aneurysm clips. (Most clips placed in the last 15 years are non-ferrous, but need an operative report to confirm non-ferrous nature.)
- Morbid obesity > about 300 lbs, depending on scanner. (Some newer scanners will allow up to 400 lbs.)
- Tattoos with ferromagnetic ink. How many Hounsfield units is water? ANSWER Water = 0 HU Metal: >1, Bone: 500 to 1, Soft tissues (e.g., Liver, spleen, bowel wall, muscle, brain parenchyma): 30 to 60 without contrast Fluid (e.g., cysts, gallbladder and bladder contents, CSF): 10 to 20 Water: 0 Fat: - 50 to - 100 Air: - 1, What is the technical explanation for using contrast? ANSWER Intravenous contrast will increase the density (thus increasing the HU) of many soft tissues, as well as that of blood, depending on the blood flow to
the tissue and the time that the scan was acquired relative to the contrast injection. Complex fluid collections (infection, hemorrhage, etc.) can measure higher than water density Why isnt D-dimer good for hospitalized and post procedural patients? ANSWER They already have fibrinogen products active in their body so theres a high likelihood for a meaningless positive test (just go to CT or US in these cases) Explain a V/Q scan The perfusion is performed by injecting technetium- labeled macroaggregated albumin particles intravenously. These "stick" in the smaller pulmonary capillaries as they are larger than the capillaries, and remain there for several hours until phagocytosed. The particles only occlude a small percentage of precapillary arterioles and capillaries (we certainly don't want to occlude them all!), but the distribution of the particles provides us with a perfusion map of the lungs. The ventilation study can be performed in various ways, most commonly by the patient inhaling another Tc-99m labeled tracer (DPTA), which is aerosolized with a nebulizer or radioactive xenon gas. When is a V/Q scan indicated? ANSWER When looking for a pulmonary embolism but the patients kidney's cant handle the contrast needed for a CTA (CT angiography / helical CT) What is the "weakness" of a V/Q scan? ANSWER IF the lungs are already abnormal - eg. BAD emphysema or COPD - then the scan is going to look very confusing Intermediate probability scans basically tell you NOTHING (probability of a PE is 20-79%) these ARE good for a rule out though - if totally normal then you nearly are CERTAIN theres no PE
CXR findings of pulmonary edema? ANSWER Peribronchial cuffing (related to edema around airways) Blurring of vascularity Upper lobe venous distention Perihilar fuzziness (also called perihilar haze) Kerley B (and A and C lines.) Fluid in the fissures Alveolar consolidation (see next page) Pleural effusions Cardiomegaly Kerley A lines are longer and directed towards the lung hilar. Kerley C lines are randomly directed lines. All represent fluid or thickening of the interlobular septa between secondary pulmonary lobules. THese lines can also be due to fibrosis - not just edema Besides CHF, what other conditions cause Kerley B lines? ANSWER Lymphangitic carcinomatosis Viral pneumonia, occasionally Mycoplasma pneumonia Asbestosis Mitral stenosis Fibrosing mediastinitis Pulmonary vein stenosis What other causes can lead to increased cardiothoracic ratio when the heart is normal sized? ANSWER Causes of an increased cardiothoracic ratio where the heart is normal: AP films Pericardial effusion Obesity Pregnancy Pectus excavatum Large breasts (increasing distance from receptor) Lordotic or rotated study What is a trauma series include? ANSWER AP chest
AP pelvis ± lateral C-spine What is a FAST scan? ANSWER FAST (focused assessment with sonography for trauma) scan is a limited ultrasound examination to look for free intraperitoneal and pericardial fluid. In the context of trauma, fluid is likely to represent hemorrhage. FAST scans focus on looking in four main areas in the abdomen and pelvis using portable ultrasound equipment. FAST scans look in 4 main areas:
- Perihepatic
- Perisplenic
- Pelvic
- Pericardiac When these are POSITIVE patient may then be sent for CT scan or straight to the OR Clues to a bladder/urethral injury? ANSWER Blood at urethral meatus, Widened pubic symphysis Major structures to check when reading a pelvic trauma x-ray? ANSWER A. Check that all three pelvic rings (main pelvic ring and the obturator rings) are intact:
- Superior ramus extends laterally from the body, forming part of the acetabulum
- Inferior ramus joins the ischium
- These two rami enclose part of the obturator foramen B. Make sure pubic symphysis is not widened (< 1cm) C. Look at sacroiliac joints: Symmetrical? ANSWER Widened? ANSWER D. Look at proximal femora: Femoral heads dislocated? ANSWER Fracture of proximal femur? ANSWER
