OBJECTIVES 1. Identify normal anatomic structures of the chest and their spatial relationships to one another 2. Display familiarity with the basic principles of radiography (e.g. radiolucency, silhouette sign, artifact r/t technique) CHEST X‐RAY INTERPRETATION 3. Establish a systematic approach to viewing and Dan Jacobson, MSN, RN, CPNP‐AC evaluating the pediatric AP chest X‐ray Rady Children’s Hospital San Diego October, 2013 4. Recognize common patterns of abnormality observed in the pediatric AP chest X‐ray DISCLOSURES None FUNDAMENTAL PRINCIPLES & CHEST ANATOMY HISTORY CREATING A RADIOGRAPH 1895: Wilhelm Conrad Roentgen discovered new X‐rays composed of short wavelength form of radiation that could penetrate solid electromagnetic radiation that penetrates solid objects & cause fluorescence objects based on the material’s density Since this radiation was invisible with poorly A radiograph (XR) is created when x‐rays understood properties, he named it “x‐ray” penetrate an object & produce images on a piece of photographic film Alternate terms: radiography, roentgenology RADIOLUCENT VS. RADIOPAQUE 4 BASIC ROENTGEN RADIODENSITIES Higher x‐ray penetration occurs through Gas / Air structures of low density and results in (Air in trachea, bronchi, stomach) dark/black areas on the radiograph Radiolucent (radiolucency) Fat / Soft Tissue (Lipid tissue around muscle) Lower x‐ray penetration occurs through structures of high density & results in light/white Water areas on the radiograph (radiopaque) (Heart, blood vessels, muscle, diaphragm) Radiopaque Bone / Metal (Bones, calcium deposits, prosthesis, contrast) SILHOUETTE SIGN Bone Occurs when structures of similar density are Bone adjacent to each other Air Borders of structures become undetectable Fat Fat Distinct structures may then appear to be a single mass Water Helpful in identifying chest abnormalities (e.g. lung disease) Air Knowledge of normal chest anatomy is key Water SILHOUETTE SIGN Trachea Carina R & L Main Bronchi RUL LUL • Adjacent to trachea and • Adjacent to trachea and R bronchus L bronchus • Primarily anterior structure • Primarily anterior structure • Common site of atelectasis Lingula RML (Inferior Portion of LUL) • Adjacent to heart • Adjacent to heart • Also anterior structure LUL RUL • L cardiac border lost with • R cardiac border lost with presence of infiltrate or presence of infiltrate or Lingula atelectasis atelectasis LLL RML RLL LLL • Adjacent to diaphragm • Adjacent to diaphragm • Primarily posterior • Primarily posterior structure RLL structure R L Posterior ribs Trachea Clavicles 1 Articulate with 2 1 vertebral Carina 3 2 column Heart 4 SVC‐RA junction 5 3 6 Aortic knob Anterior ribs 7 4 Mediastinum Fade towards Hilar area 8 5 mediastinum Diaphragm 9 6 Gastric bubble Costophrenic sulci EG junction CHEST VIEWS PA (Posterioranterior) XR beam passes thru chest from back to front Film plate placed against anterior chest & XR tube approx 6 ft. behind pt CHEST VIEWS Best quality with regard to minimizing distortion and magnification artifact & TECHNIQUE CHEST VIEWS TECHNIQUE AP (Anteriorposterior) Under Vs Overpenetrated Film XR beam passes thru chest from front to back Proper penetration = thoracic spine should be faintly visible through cardiac shadow Film plate placed behind pt’s back & XR tube approx 36‐40 inches from chest Underpenetration: XR appears too light d/t underexposure (soft tissues appear too white, Most common view for hospitalized pt diaphragm borders may be lost) Heart size magnified d/t increased distance from film plate & closer proximity of XR tube Overpenetration: XR appears too dark d/t overexposure (edge of soft tissue skin line Less distinct borders between structures difficult to locate, lung markings may appear absent) TECHNIQUE TECHNIQUE Rotation Rotation Rotation = twisting of chest to the left or right Tips for detecting rotation away from the XR tube which skews location/size Clavicles: In normal unrotated CXR medial ends of of anatomic landmarks clavicles should be equidistant & appear CXR with rotation creates abundant opportunity symmetrical (best for >3 yrs) for artifact (esp. with regard to heart, lung fields, Anterior ribs: If one side has longer ant rib & mediastinum) segments, then pt is rotated to opposite side Lung fields: If one lung is more radiolucent, then pt rotated towards same side Cardiac shadow: If overtly shifted to one side, then pt rotated towards same side MARKED ROTATION SAME PATIENT: MINIMIZED ROTATION SYSTEMATIC APPROACH & COMMON FINDINGS A SYSTEMATIC APPROACH 1. AIRWAY ‐ TRACHEA Airway (trachea) Column of radiolucent gas density midway Bones (thorax / ribs / IC spaces) between the clavicles and over the spine th Cardiac (heart / mediastinum / hilum) Carina near the level of 6 posterior rib Diaphragm Abnormal findings: Tracheal deviation or narrowing Soft tissues Malpositioned ETT Pleural surfaces FBO Lung fields Tubes (tubes, catheters, lines, wires, etc.) ANATOMIC TRACHEAL ABNORMALITY TRACHEAL NARROWING / STEEPLE SIGN TRACHEAL DEVIATION AFTER CHEST TUBE INSERTION 2. BONES ‐ THORAX / RIBS / IC SPACES 2. BONES ‐ THORAX / RIBS / IC SPACES Visualized bone densities: clavicles, ribs, spine, & Intercostal spaces numbered according to humeri superior rib (thus 1st ICS is below 1st rib) Posterior ribs articulate with vertebral column Abnormal findings: Asymmetry (rotation vs. actual?) Anterior ribs fade towards mediastinum (d/t low Fx density cartiliginous connective tissue) Scoliosis Clavicles are landmark for thoracic inlet Widening / narrowing of IC spaces CLAVICULAR FX BILATERAL RIB FRACTURES R RIB FRACTURES WITH CALLUS RIB ANOMALIES & SCOLIOSIS 3. CARDIAC –HEART / MEDIASTINUM 3. CARDIAC –HEART / MEDIASTINUM Mediastinum comprised of trachea, heart, major Presence of thymus in superior mediastium blood vessels, R & L bronchi (combination of common in infants (usually undetectable by 5 yrs water & air densities) of age) R heart border formed by RA (RA is approx two Abnormal findings: vertebral bodies beneath the carina) Mediastinal deviation (atelectasis, mass, PTX) L heart border formed by LA & LV Widened mediastinum (hemorrhage, mass, thymus) Cardiomegaly (myocarditis, CHF, CHD, fluid overload) 2/3 of heart normally lies to the left of the midline Narrowed cardiac shadow (hypovolemia, hyperinflation) Normal cardiothoracic ratio < 50% (horizontal width of the heart divided by the widest interval of the thorax) CARDIOMEGALY THYMUS 70% WIDENED MEDIASTINUM 3. CARDIAC –HILUM Consists of pulmonary arteries & veins in the central chest Blotchy appearance r/t various areas of radiopacity associated with sizes & densities of vasculature L hilar area obscured by heart shadow so appears smaller & more elevated than R hilum Abnormal findings: Prominence/thickening of upper lobe vessels Dilation of hilar trunks PROMINENT PERIHILAR MARKINGS 4. DIAPHRAGM Appears as water density with each hemidiaphragm being dome‐shaped R hemidiaphragm usually higher than L hemidiaphragm d/t presence of liver EG (esophogeal gastric) junction located where L hemidiaphragm meets L side of thoracic spine Abnormal findings: Elevation (atelectasis, phrenic nerve injury) Flattening (hyperinflation, PTX) HYPERINFLATION HYPERINFLATION BI‐BASILAR ATELECTASIS 5. SOFT TISSUES Primarily consist of fat & water densities within the chest Should be symmetrical Abnormal findings: Subcutaneous emphysema Anasarca ANASARCA SQ EMPHYSEMA & PNEUMOMEDIASTINUM 6. PLEURAL SURFACES PLEURAL EFFUSION Pleurae normally appear as thin lines along lateral edges of the chest and diaphragm Costophrenic sulci should be distinct sharp points at the lateral lung bases (resemble V’s) Abnormal findings: Pleural line medial deviation (effusion, PTX) Blunted costophrenic sulci (effusion) Deep sulcus sign (PTX) PNEUMOTHORAX PTX: AFTER CT INSERTION 7. LUNG FIELDS 7. LUNG FIELDS Predominantly air density with minimal tissue or Hypoventilation or expiratory film blood (high radiolucency) Lung markings appear crowded/compressed with Both lungs should have similar lucency hazy bases bilaterally Enlarged heart shadow ( cardiothoracic ratio) Adequate inspiration Abnormal findings: 6‐7 anterior ribs or 8‐9 posterior ribs visible above diaphragm Airspace disease – consolidation or atelectasis Less than 1/3 of heart projected below Interstitial disease hemidiaphragms Asymmetry Both hemidiaphragms rounded Hypoventilation CLEAR LUNG FIELDS HYPOVENTILATION AIR SPACE DISEASE (ALVEOLI) CONSOLIDATION / INFILTRATE Reduction in alveolar air volume d/t Characterized by opacities in lung fields that may consolidation (infiltrates) and/or atelectasis appear as silhouette sign or include air bronchograms Consolidation / infiltrate = replacement of air in alveoli with fluid or tissue Commonly caused by respiratory infection or edema Atelectasis = alveolar collapse Less common cause: malignancy/mass RLL CONSOLIDATION BILATERAL INFILTRATES INFILTRATES WITH AIR BRONCHOGRAMS BILATERAL MASSES ATELECTASIS ATELECTASIS Characterized by lung opacities that may shift Primary contributing factor is often position of chest structures towards atelectatic hypoventilation region (e.g. mediastinum, diaphragm) Distinguished from consolidation by: Common Causes / Types Shifting position on CXR over serial exams Resorptive: air absorbed from alveoli d/t Homogeneous density (infiltrates more likely to compromised ventilation from obstruction above level of alveolus (e.g. mucus plug, FBO, mass) be patchy