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Chest X-ray Interpretation 26 September 2024 By Lauren Merriman-JonesUse code CBOSCECREW24 at checkout on geekyquiz.com for 10% off OSCE flashcards, OSCE stations and knowledge bundles. Why do we even order chest x-rays? ● Are performed in both acute (A&E, SDEC) and non-acute settings (GP and in-patients) ● Chest pain ● Fever - infection source? sepsis source? ● Persistent cough – pneumonia? lung cancer? ● Abdominal pain – perforation? ● Breathlessness - fluid overload? pneumonia? COPD? ● Traumatic injury – pneumothorax? broken ribs/bones? Why choose a chest x-ray over other imaging? - Quick to perform (no preparation required) - Can be performed on bed bound and mobile patients - Cheaper imaging alternative (<£100) - Low dose of radiation exposure - CXR = 0.02 mSv - Radiation exposure over a year = 2.4 mSv - CT chest = 7 mSv - CTPA = 15 mSv • 7 million CXRs are performed a year in England The X-ray Basics ● X-rays are a type of radiation that can pass through most objects ● Passing x-ray radiation through the human body generates a 2D image, casting a “shadow” ● This “shadow” represents different structures inside the body according to their density ● Less dense = dark/black (e.g. the lungs) ● More dense = dark grey/white (e.g. bones or tumours)How do I interpret a CXR? RIPE ABCDE 1. Confirm details of the patient 2. Assess image quality – RIPE 3. ABCDE approach - Geeky medics have the same structure on their website for further revision - All 3 parts required for data interpretation stations in OSCE of CXR Confirm patient details ● Name, DOB and hospital/NHS number (if provided) ● Date and time CXR was taken ● If possible – a previous CXR for comparison Mistakes happen, make sure you are always looking at the right patient’s x-ray!Assessing image quality = RIPE RIPE - Rotation - Checking that the patient is correctly rotated when the x-ray was taken - If the rotation is correct: - (1) Vertebral spinous processes should be aligned vertically - (2) Medial ends of the clavicles should be the same distance away from the spinous process that sits in-between them RIPE - Inspiration - When taking an CXR image, the patient is asked to breathe in and hold - If the inspiration is adequate: - (1) A minimum of 5 anterior ribs will be visible (ribs sloping downwards) - (2) Visualise BOTH lung apices (space above clavicle) - (3) Visualise both costophrenic angles (bottom 2 corners) RIPE - Projection - Look to whether this is an anterior-posterior (AP) or posterior-anterior (PA) film - AP film = x-rays are sent through the anterior portion of the chest, best for bed bound patients, patients who have problems mobilising or in an emergency - Can either be performed sitting or lying supine (this will be marked) - PA film = x-rays are sent through the posterior portion through the chest - Performed standing (ie erect) - PA film is the “standard” chest x-ray – it produces the best image - If there is no label on a CXR, assume it is PA RIPE - Projection - Differences between PA and AP CXRs: - Heart size is exaggerated in AP film (best not to draw conclusions about heart size/cardiac findings in an AP CXR) - Visible scapula in AP film lung field edges (this is due to patients not being asked to cross their arms over their chest) Underexposed = too Overexposed = too dark white RIPE - Exposure - This relates to the penetration of the x-rays through the tissues - Adequate exposure allows us to visualise pulmonary vessels, lung fields and bones accurately - Overexposure = darker lung fields and makes the pulmonary vessels more difficult to visualise - Underexposed = whiter lung fields and makes the bony anatomy more difficult to inspect - To check for appropriate exposure: - LEFT hemidiaphragm should be visible all the way to the spine - Vertebral bodies should be visible behind the heart, just (not clearly visible or not there at all)Structured interpretation of tAirway, Breathing, Cardiac, Diaphragm, Everything Else ABCDE - Airway - Assess the 4 key parts of the airway: - (1) Trachea - (2) Carina (where the trachea deviates into the two bronchi) - (3) Bronchi - (4) Hilar ABCDE - Airway - Trachea = is there deviation? - Normal = central or slight deviation to the right - Deviation is either ‘true’ or ‘apparent’ - A trachea that is “truly” deviated is either being pushed or pulled - Pushing of trachea = Large pleural effusion, tension pneumothorax, diaphragmatic hernia and thoracic mass - Pulling of trachea = Pneumonectomy, lung collapse - Apparent deviation is when the patient is rotated incorrectly, this should be identified when identifying image quality - If true, comment on direction of deviation - Whether the trachea is being pushed or pulled can be identified in later stages ABCDE - Airway - Carina and Bronchi = are they visible? - Normal CXR = carina should be clearly visible - Right bronchus is more vertical, wider and shorter than the left - If ?foreign body inhalation, it is more likely to be in the right bronchus as it will fall into the more vertical bronchi ABCDE - Airway - Hilar = Any Enlargement? Abnormal position? Hilar point visible? - Normal CXR = same size, hilar point visible and left hilar sits higher (although variable) - Enlargement: - Unilateral = ?malignancy - Bilateral = ?sarcoidosis or ?TB - Abnormal position: - Pushing of hilar (?soft tissue mass) or pulled (?lung collapse) - Absent hilar point: - Lesion at the point (?lung tumour or lymph node enlargement)Bilateral enlargement of hilarUnilateral enlargement of hilar ABCDE - Breathing - Inspecting the breathing = inspecting the lung fields and pleura for abnormalities - The lung should be divided into 3 zones on both sides (this is more for description of pathology, not anatomically accurate ABCDE - Breathing - Lungs: - The lung fields should not be completely white or completely black, there should be lung markings throughout the fields - Systematically inspect each zone of the lung – - Absence of lung markings (black lung fields) - ?pneumothorax (inspect pleura next) - White shadowing/increased shadowing – consolidation, pleural effusion, collapse, pneumonectomy (lung removal), tumours, pulmonary oedema - Pulmonary oedema will often be bilateral/symmetrical - If you find any abnormalities, comment on the zone(s) it is found in, is it unilateral or bilateral (e.g. there appears to be some consolidation in the right lower lung zone, not apparent on the left) - Ensure you have examined the apices for pathology as this often gets missed!!Consolidation is fluid in the alveoli and bronchioles – this fluid can be pus (pneumonia), fluid (pulmonary oedema), blood or other material It will appear as a white or patchy white area on the lung field with no volume loss in the lung 🡨Consolidation on the right middle to lower zone🡨Consolidation on the right middle to lower zone, left lung is clear and has normal lung markingsPleural effusion is fluid accumulating the pleural cavity. This can be fluid, pus, blood etc. CXR cannot distinguish between these so pleural effusion includes everything. - Looking for the meniscus of the fluid for pleural effusion with a opaque white area 🡨 Pleural effusion of the left lung up to the upper zone (tracheal deviation can also be seen)🡨 Pleural effusion of the left lung in the lower zone, more specifically the costophrenic angleLung collapse - Commonly caused by lung cancer, asthma or foreign bodies - Signs we look for: white shadow over lung field, tracheal deviation & mediastinal shift TOWARDS the side of collapse and elevation of hemidiaphragm on the same side 🡨 White shadow (increased density) on the right upper zone that extends into the middle zone - For note this CXR is of right upper lobe collapseLung masses - Often a white-grey, well defined mass - Image does not distinguish between a cancerous mass or a mass of other contents (e.g. abscess) - Effusion may be present (can mask a mass as well if cancerous) 🡨 Increased density, over left middle zone, likely to be a lung massPulmonary Oedema – Fluid leaking from pulmonary capillary network into lung interstitium and alveoli (lymph system is unable to clear fluid) - Either cardiogenic (ie heart failure) or non-cardiogenic (e.g. severe liver disease) - Pulmonary oedema has some key findings: - (1) Interstitial oedema - (2) Kerley B lines - (3) Pleural effusion - (4) Cardiomegaly - (5) Upper lobe diversion (Stag antler’s sign)- Table above is from PassMed - Causes of tracheal deviation when there is increased density/white shadow over the lung fields - Pulling of the trachea – think of it like a breech in a spaceship, things inside are pulled out into the vacuum of space - the trachea is pulled into the vacuum of the “lung” - Pushing of the trachea – the contents inside the lung are so large they have to push outwards into the rest of the chest cavity ABCDE - Breathing Pleura - Looking for abnormalities - On a normal CXR, the pleura should not be visible - To inspect: - Inspect the borders of each lung looking for lung markings extending to all edges - Pleural is visible = thickening = mesothelioma (asbestos exposure) - Absence of lung markings = pneumothoraxSimple Pneumothorax – air collecting in the pleural cavity resulting in collapse of the lung if enough air is present - Pleura has come away from the lung edge (thin white line) and left a black space (outside of the line) - No tracheal deviation or mediastinal shift 🡨 Right sided pneumothoraxTension pneumothorax - accumulation of air that is unable to escape, causing lung collapse and mediastinal shift. This is life-threatening as it reduces cardiac output (CV collapse possible) How it appears on CXR: - Same features of simple pneumothorax + mediastinal shift AWAY from affected side + tracheal deviation AWAY from affected side You do not often see tension pneumothorax on CXR as only clinical diagnosed is needed. Imaging delays treatment as this will kill the patient.Mesothelioma – cancer of mesothelial layer in pleural cavity (associated with asbestos exposure) - Often pleural thickening is seen +/- pleural effusion ABCDE - Cardiac 1. Assess heart size (PA CXR ONLY) - Normal – Heart is taking up a maximum 50% of thoracic width - Cardiomegaly – Heart is taking up >50% of thoracic width - Causes of cardiomegaly: valvular heart disease, cardiomyopathy, pericardial effusion, heart failure ABCDE - Cardiac 2. Assess heart borders ○ In normal individuals ■ Right atrium makes up most of right heart border ■ Left ventricle makes up most of left heart border ○ Abnormal pathology findings ■ Pathology can increase opacity of overlying lung tissues = borders are hard to see ■ Reduced definition of R heart border = likely right middle lobe consolidation ■ Reduced definition of L heart border = likely lingular consolidation ABCDE - Diaphragm Normal diaphragm on CXR: - Right hemidiaphragm is higher than the left (liver presence) - Often there is a gastric bubble under the left hemidiaphragm from the stomach - Diaphragm is not discernible from liver underneath - Costophrenic angles (lateral chest wall and dome of hemidiaphragm) are clearly visible with an acute angle ABCDE - Diaphragm Abnormalities seen at diaphragm: - Free gas (from perforation of GI tract) under right hemidiaphragm separates it from the liver - Flattening of diaphragm & “costophrenic blunting” - ?COPD (lung hyperinflation) - Loss of costophrenic angle - ?fluid or ?consolidation in the lower zones of the lung ABCDE – Everything Else This includes the following: - Mediastinum - Bones - Soft tissues - Medical equipment visible ABCDE – Everything Else Mediastinum - In the mediastinum is the heart, great vessels, lymphoid tissues and potential space - There are 2 important structures to address in the mediastinum: - (1) Aortic knuckle - (2) Aortopulmonary window (the wedge) ABCDE – Everything Else Aortic knuckle (mediastinum) - This is at the left lateral edge of the aorta - Reduced definition/enlarged = aneurysm Aortopulmonary window (mediastinum) ○ The space between arch of aorta and pulmonary arteries ○ Space loss = Mediastinal lymphadenopathy (e.g. malignancy) ABCDE – Everything Else Bones - Inspect all visible skeletal structures – any fractures or other lesions? - This includes arms or collarbones Soft Tissues - Looking for soft tissue for obvious abnormalities (e.g. large haematoma) ABCDE – Everything Else Medical Devices on CXR - NG Tube (should dissect the carina) - Lines (e.g. central line or ECG cable) - Artificial heart valves (ring-shaped structures) - Pacemaker (in infraclavicular region connected to pacemaker wires) Things to Add/OSCE advice: ● In the OSCE CXR will either be in: ○ (1) A data interpretation station (alongside ECG, blood work, a history etc) for you to make a differential and provide a management plan – no simulated patient present (2) With a simulated patient, you will be asked to take a history and then interpret a CXR (or can be any investigation) to produce your most likely differential ● For level of knowledge: Geeky medics, PassMed and TCD online/in-person (as a minimum) ● In an exam they can show you normal results of CXR (or other investigations) ● If you don’t know what the diagnosis is – always fall back on RIPE ABCDE and show your workings, not knowing the diagnosis is not automatic fail ● At the end summarise findingsAny questions so far?Let’s Practice Analysis…Pneumonia (right lower zone consolidation)COPD – Hyperinflation - >6 anterior ribs visible - Flattened diaphragm - Hyperlucent lungs (excess of air = darker)COPDCardiomegalyLeft pneumonectomyNormal CXRSimple pneumothoraxLung MassTotal right sided lung collapse Left lingula consolidationTension PneumothoraxPleural EffusionApical Pneumothorax Thank you! Any questions?