Radiology Notes Monday, August 19, 2013 2:37 PM http://fitsweb.uchc.edu/student/radiology http://www.med-ed.virginia.edu/courses/rad/index.html http://www.radiologyassistant.nl/en/p497b2a265d96d/chest-x-ray-basic-interpretation.html#in514d80fcb1408 http://www.stritch.luc.edu/lumen/MedEd/Radio/curriculum/Medicine/Pleural_effusion1.htm TEST 2 hours - 80 questions Management, next step, cases with images, just an image Images repeated on exam that we saw in class Introduction to Radiology/Imaging Plain Film Plain x-ray is a 2D representation of a 3D object. Only when you see the object in two planes can you see what something is and define it’s true shape X-rays have 5 tissues you can identify based on absorption coefficient; need difference in absorption coefficient of 5% o Air (black): photo does right through and doesn’t get absorbed; -1000 o Water, muscle, blood, soft tissue (gray) o Fat (dark gray) o Bone (white): calcium o Metal (white); +1000 Brightness on x-ray: lead > barium > bone > muscle/blood > liver > fat > air Normal chorinal angle is about 70 degrees. There are subchorinal LNs which can elevate the main stem bronchus PA vs. AP – always labeled by direction of path of beam (supine is AP, anterior to posterior) o routine lateral is called left lateral, beam goes from right to left Collimator – lead square used to limit boundaries of x-ray beams; triangulation: use images with history and physical Too much light = over exposed, so looks black; not enough light = underexposed (energy can’t quite penetrate) MRI Non-ionizing radiation, Great for looking at soft tissues Contraindication with pacemakers/ferromagnetic devices T1 - fluid is black T2- fluid is white Fluoroscopy Continuous stream of x-ray to watch what’s going on in real time; can watch motion Downside is higher dose of radiation Can use with contrast agents o Inulin gets picked up by the kidney; Intravenous Pyelogram = inulin tagged with iodine CT X-ray in thin slices; very sensitive; each line = ray; 1000 slices of 1mm cuts Each slice has three dimensions Orient yourself look at patient’s feet, upward Nuclear Imaging Outgrowth of Manhattan project (development of first atomic bomb) Radiation with alpha/beta/gamma PET (Positron Emission tomography) scan: tag positron with glucose and look for metabolically active tumors o Hope is to one day tag it so it can destroy these areas Ultrasound High frequency sound waves in water (know speed of sound in water) No ionizing radiation, relatively inexpensive, real time evaluation, can utilize color Doppler to look at flow Applications: liver, gallbladder, biliary system, kidney; terrible with bowel Radiation Dangers and Protection Unit of energy in x-ray is called a Rad o Difference in absorption in different types of tissue Sievert is the amount of radiation a particular unit of tissue receives For the average CT of chest or abdomen, dose is 10-15 milliSieverts (CXR is .01 mSv) o CTA is 15-20 milliSieverts o Average CXR is 0.01 milliSieverts o 10milliSieverts = 1/1000 risk of developing cancer o Abdominal CT scan: 1/143 risk o Normal radiation from natural sources – normally 1-3 mSv/year . In areas of high background, 3-13 mSv/year o Over 50 mSv at one time is high risk for developing cancer Radiation injury: When you get a photon of energy that comes through the tissue at the right amount, it knocks out one of the outer electrons and creates and ion (in water, activates hydroxyl ion). This can potentially cause damage to your DNA. Photon can actually damage the DNA or break the strand if it hits it directly. Rotations Page 1 hydroxyl ion). This can potentially cause damage to your DNA. Photon can actually damage the DNA or break the strand if it hits it directly. Optimization of protection by keeping exposure as low as reasonably achievable; dose limits for occupational people Medical, occupational, and public exposures all exist CHEST 40% of all imaging done in US are CXR Adequate film: o CXR ideally done in PA position, which is better for heart size (10-20% overestimation when do an AP). Done at 72 inches at maximal inspiration . Normal heart should be less than 50% of cardiothoracic ratio o Adequate inspiration: 9 posterior ribs on R side; if see 11-12 ribs, likely COPD . 2nd anterior rib follow-up, corresponds to 2nd posterior rib o Non rotation: clavicles should be equidistant from clavicles . If spinous process closer to left clavicle, then rotated left anterior oblique o Degree of penetration: . densitometer, vertebral bodies through the density of heart, pulm vascularity to LLL through heart o Routinely take left lateral (want heart on left side of chest closest to the film) Systematic Approach o Bony framework . Bony structures: cervical spine, clavicles, AC joint and acromion, scapula, glenoid, coracoid process, humeral head, ribs, vertebrae, pedicl es (will often see metastatic disease here) o Soft tissues . Soft tissue: calcification of carotid, LN calcification, masses, abdomen, stomach bubble, splenic flexure, neck and chest wall o Lung fields and hila (see his tutorial) . Right upper, middle and lower lobes; left upper and lower lobes . Left The right lung comprises 10 segments: 3 in the right upper lobe (apical, anterior and medial), 2 in the right middle lobe (me dial and lateral), and 5 in the right lower lobe (superior, medial, anterior, lateral, and posterior). 1 fissure- oblique . Right The left lung comprises 8 segments: 4 in the left upper lobe (apicoposterior, anterior, superior lingula, and inferior lingul a) and 4 in the left lower lobe (superior, anteromedial, lateral, and posterior). 2 fissures . TB likes posterior segment of upper lobe . Immunocompromised- superior segment of lower lobe o Diaphragm and pleural spaces . Right hemidiaphragm is higher than the left – if left higher may have loss of lung volume (e.g. atelectasis) o Mediastinum and heart o Abdomen and neck o Pit falls . Poor inspiration . Over or under penetration . Rotation Lungs o Upper, middle, lower lung field; hilar structures including PA and PV; pulmonary vascularity, diaphragm, costophrenic sulcus; right hemidiaphragm is usually higher than left (if left higher, might be phrenic nerve palsy but most commonly loss of lung volume such as atelectasis; tumor). Then compar e one side to the other o Carina . Look for lymph nodes in this area (e.g. stage 4 lung cancer, no longer operable) Silhouette/Structure Contact with Lung Upper right heart border/ascending Anterior segment of RUL aorta Right heart border RML (medial) Upper left heart border Anterior segment of LUL Left heart border Lingula (anterior) Aortic knob Apical portion of LUL (posterior) Anterior hemidiaphragms Lower lobes (anterior) (right anterior oblique = left posterior oblique) Medial segment of middle lob abuts the heart Rotations Page 2 Rotations Page 3 Heart o Cardiac shadow/size. Borders of heart, trachea and bifurcation, atria/ventricles o Right atrial enlargement . Could be tricuspid regurgitation . Right sided strain Lateral view o Square vertebrae, aorta and scapula look a bit different. Lungs should be blacker as you go down in a lateral view. o On lateral, to know which diaphragm you’re looking, gastric bubble on left. Left hemidiaphragm has heart on it Silhouette sign – two tissues of similar densities that are next to each other, you won’t be able to recognize the difference o Vertebra should get progressively darker as you go down Look at segments : o right upper lobe segments – superior, anterior, posterior (posterior associated with TB); left upper lobe segments – anterior, apical posterior; right lower lobe – superior, anterior, posterior, mediolateral Pathology / other o Tracheal deviation: thyroid, thymus, teratoma, etc. o Most common cause of perforated viscous is an ulcer (duodenal or gastric). Anytime you suspect a perforation or a leak from an anastomosis etc ----can ONLY use water soluble contrast!!! . Other causes- diverticulitis (unusual), iatrogenic, colon (intraperitoenum – cecum, transverse, sigmoid, jejunum) . If patient cannot stand, do Left Lateral Decubitus Do left side down so that air goes up to right side and see air above liver Rotations Page 4 Do left side down so that air goes up to right side and see air above liver o Hiatal hernia – can see it hyper dense behind the heart. On lateral, see air pocket o May occasionally have cervical (rudimentary) ribs, air in subcutaneous tissue, absence of clavicles etc. Can use a grid to c lean up scatter. Consolidation and atelectasis (collapsed alveoli – can be due to obstructive (plugging), compression (fluid collection), scarring) o air bronchogram – can see bronchus clearly because alveoli are filled with something (consolidation or atelectasis, differentiate by clinical f indings) . if see bronchograms, can’t be due to something plugging up bronchus . An air bronchogram is a tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammat ory exudates. Six causes of air bronchograms are; lung consolidation, pulmonary edema, nonobstructive pulmonary atelectasis, severe interst itial disease, neoplasm, and normal expiration. o Any time you see loss of volume, post-obstructive pneumonias can occur MUST obtain follow-up x-ray 4-6 weeks o Loss of volume = atelectasis due to endobronchial obstruction lesion (e.g. carcinoma) o Look at level of diaphragms for evidence of loss of volume. Can also have mediastinal shifting due to loss of volume. o *If see heart right border, RIGHT MIDDLE LOBE normal. o Can see growth plates in humeral heads signifies child o Ex. RLL pneumonia --- can see heart border on lateral CXR (posterior border of LV) o Lingula blocks left horder border Elevated left hemidiaphragm o Loss of volume - atelectasis, PNA o Abdomen mass pushing it up o Ascites (should push up both) o Paralyzed left hemidiaphragm Tension Pneumothorax ○ If ever a question of pneumothorax, order an expiratory CXR.