Basics of Diagnostic Imaging PDF

BASICS OF DIAGNOSTIC IMAGING D A M I A N C O L E D O FA C E P  OBJECTIVES 1. DESCRIBE THE ROLE OF DIAGNOSTIC IMAGING IN MODERN MEDICAL PRACTICE. 2. BECOME FAMILIAR WITH THE COMMON IMAGING MODALITIES. 3. LIST AND DESCRIBE THE FIVE BASIC DENSITIES IN DIAGNOSTIC...

BASICS OF DIAGNOSTIC IMAGING D A M I A N C O L E D O FA C E P  OBJECTIVES 1. DESCRIBE THE ROLE OF DIAGNOSTIC IMAGING IN MODERN MEDICAL PRACTICE. 2. BECOME FAMILIAR WITH THE COMMON IMAGING MODALITIES. 3. LIST AND DESCRIBE THE FIVE BASIC DENSITIES IN DIAGNOSTIC IMAGING. 4. LEARN HOW TO ORIENT YOURSELF TO AN IMAGE. 5. UNDERSTAND COMMON RADIOGRAPHIC LANGUAGE AND DISCUSS HOW TO ORDER THE CORRECT EXAMINATION. 6. IDENTIFY THE COMMON CLINICAL USES OF THESE IMAGING MODALITIES. 7. COMPARE AND CONTRAST THE DIFFERENT MODALITIES IN TERMS OF IMAGE QUALITY, DIAGNOSTIC ACCURACY, AND PATIENT SAFETY. 8. UNDERSTAND SAFETY LIMITATIONS OF EACH IMAGING MODALITY  DESCRIBE THE ROLE OF DIAGNOSTIC IMAGING IN MODERN MEDICAL PRACTICE.  Diagnostic imaging of all varieties is an extremely important tool in the diagnosis and treatment of many medical conditions.  Imaging is used to diagnose a wide variety of orthopedic, vascular, pulmonary, gastrointestinal, obstetric, urologic and neurologic conditions to name a few.  Therapeutic radiation will be discussed at another time, but it is used in many aspects of medicine, most notably oncology.  Interventional radiology is another topic to be discussed later but it deals with the use of live radiographic imaging in the assistance of performing many diagnostic and therapeutic procedures. BECOME FAMILIAR WITH THE COMMON IMAGING MODALITIES.  THE MAIN SUBTYPES TO BE AWARE OF ARE IONIZING RADIOGRAPHY, MAGNETIC RESONANCE IMAGING (MRI), NUCLEAR MEDICINE IMAGING, AND ULTRASONOGRAPHY. IONIZING RADIOGRAPHY  Ionizing radiography includes X-ray, fluoroscopy, and computed tomography (CT).  This type of imaging is performed by shooting ionizing radiation through the patient and onto a photosensitive surface to produce an image. In the past this would have been completed using a special type of photographic film. This process has largely been replaced by digital photosensitive plates which transmit the image to a computer for processing and viewing. MAGNETIC RESONANCE IMAGING  This type of imaging uses very strong magnetic fields and radio-frequency to produce energy in the body’s stored hydrogen atoms.  This information is sent to specialized detectors and used to generate 2D or 3D images.  MRI is commonly associated with neuroscience and orthopedics as it is able to produce the best images for diagnosis of nerve compromise, ligamentous injury, vascular insult, and operative planning. NUCLEAR MEDICINE  In nuclear medicine studies a radioactive isotope in its unstable form is introduced to the patient in various ways.  As the artificially produces isotope decays special detectors monitor the rate of decay to produce an image.  These isotopes are pharmaceutically attached to structures that give it binding properties to certain types of tissues. This helps the isotope to bind to certain tissues for the desired imaging study.  For example, the thyroid gland takes up iodine, the brain uses lots of glucose, and bone utilizes lots of phosphates.  Nuclear medicine studies include but are not limited to the following: single photon emission computed tomography (SPECT), positron emission tomography (PET), ventilation/perfusion scans, nuclear stress tests, bone densitometry, thyroid scans, hepatobiliary scan, etc. ULTRASONOGRAPHY  Ultrasound probes use acoustic energy and measures the time it takes for ultrasound waves to leave and return to the ultrasound probe.  The faster and/or the more quantity of waves that are reflected back to the probe the brighter the image. This is true of higher density structures in the body such as bone.  The slower and/or the less quantity of waves reflected back to the probe produce a darker image. This is true of lower density structures in the body such as air filled or fluid filled spaces.  Point of care ultrasonography is quickly becoming standard of care for use in many practices of medicine and for procedural guidance. LIST AND DESCRIBE THE FIVE BASIC DENSITIES IN DIAGNOSTIC IMAGING. 5 BASIC DENSITIES 1. A I R : A P P E A R S B L A C K E S T O N X R / C T/ U S 5 BASIC DENSITIES 2. F AT: L I G H T E R S H A D E O F G R AY 5 BASIC DENSITIES 3. S O F T T I S S U E O R F L U I D : T H E D E N S E R T H E F L U I D T H E G R AY E R A P P E A R A N C E , T H E L E S S DENSE THE FLUID THE BLACKER APPEARANCE 5 BASIC DENSITIES 4. C A L C I U M : M O S T LY A P P E A R S I N B O N E S B U T C A N A P P E A R I N O T H E R S T R U C T U R E S 5 BASIC DENSITIES Calcium Continued 5 BASIC DENSITIES 5. M E TA L : A P P E A R S W H I T E S T. M O S T LY F O R E I G N O B J E C T S A N D C O N T R A S T 5 BASIC DENSITIES 5. M E TA L : A P P E A R S W H I T E S T. M O S T LY F O R E I G N O B J E C T S A N D C O N T R A S T 5 BASIC DENSITIES 5. M E TA L : A P P E A R S W H I T E S T. M O S T LY F O R E I G N O B J E C T S A N D C O N T R A S T 5 BASIC DENSITIES 5. M E TA L : A P P E A R S W H I T E S T. M O S T LY F O R E I G N O B J E C T S A N D C O N T R A S T Arterial Venous  LEARN HOW TO ORIENT YOURSELF TO AN IMAGE. ORIENTATION W H AT I S U P A N D D O W N ? ORIENTATION W H AT I S U P A N D D O W N ? ORIENTATION W H AT I S U P A N D D O W N ? ORIENTATION W H AT I S U P A N D D O W N ?  UNDERSTAND COMMON RADIOGRAPHIC LANGUAGE AND DISCUSS HOW TO ORDER THE CORRECT EXAMINATION.  TERMS & CONDITIONS AP – ANTEROPOSTERIOR – REGULAR XR IMAGING L AT – L AT E R A L – R E G U L A R X R I M A G I N G C T W I T H O U T – N O C O N T R A S T – B O N E S A N D F. O.’ S CT WITH – WITH IV CONTRAST – ORGANS HIGHLIGHTED C TA – W I T H I V C O N T R A S T T I M E D F O R A R T E R I A L P H A S E MRI WITHOUT – NO CONTRAST – SOFT TISSUE, LIGAMENTS, AND BONES MRA – ARTERIAL PHASE CONTRAST - ARTERIES MRV – VENOUS PHASE CONTRAST - VEINS  TERMS & CONDITIONS INCREASED DENSITY – BRIGHTER WHITE D E C R E A S E D D E N S I T Y – G R AY E R MIXED DENSITY – AREAS OF HIGH AND LOW DENSITY AT T E N U AT I O N – I N C R E A S E D O R D E C R E A S E D – S A M E A S D E N S I T Y FLOW VOID – ABSENCE OF CONTRAST OR FLUID WHICH IS N O R M A L LY I N A S T R U C T U R E  TERMS & CONDITIONS B Y I N L A R G E Y O U W A N T T O O R D E R O N LY T H E I M A G E Y O U N E E D TO RULE IN OR RULE OUT YOUR SUSPEC TED DIAGNOSIS. P E R F O R M I N G T H E M O S T A P P R O P R I AT E E X A M Y I E L D S T H E M O S T A C C U R AT E D I A G N O S T I C R E S U LT S D E C R E A S I N G R A D I AT I O N E X P O S U R E A N D C O S T S F O R PAT I E N T S AS WELL AS THE TIME NEEDED FOR THE EXAM SHOULD BE CONSIDERED.  TERMS & CONDITIONS B O N E / C A L C I U M / F O R E I G N B O D I E S – T Y P I C A L LY D O N E W I T H X R O R C T W I T H O U T C O N T R A S T. O R G A N S / T U M O R S / M A S S E S / B L E E D I N G – T Y P I C A L LY D O N E W I T H IV CONTRAST WHICH ENHANCES THE APPEARANCE OF ORGANS A N D W I L L H I G H L I G H T A R E A S O F I N F L A M E D O R I N FA R C T E D TISSUE. A R T E R I E S A N D V E I N S – T Y P I C A L LY D O N E W I T H I V C O N T R A S T WITH SPECIAL TIMING TO HIGHLIGHT INTRA-ARTERIAL AND INTRA-VENOUS BLOCKAGES. ALSO USED TO DETERMINE PRESENCE OF ANEURYSMS AND LOOK FOR LEAKING OF I N T R A V A S C U L A R M AT E R I A L I N T O T H E E X T R A V A S C U L A R S PA C E.  IDENTIFY THE COMMON CLINICAL USES OF THESE IMAGING MODALITIES. & COMPARE AND CONTRAST THE DIFFERENT MODALITIES IN TERMS OF IMAGE QUALITY, DIAGNOSTIC ACCURACY, AND PATIENT SAFETY.  Modality Reason for Ordering Benefits Risks Image Quality Diagnostic Accuracy Good for fractures and Fractures, dislocations, lung pathology. Poor for XR pneumonia, intestinal Simple, fast, easy, cheap Radiation exposure Good internal organ related obstruction, FB location issues Fractures, dislocation, organ functions, Radiation exposure, Good for most diagnoses, Fastish, easy, relatively CT infection, inflammation, contrast allergy, not ideal Better gold standard imaging for cheap bleeding, vascular, if patient is unstable many diagnoses tumors Nervous, vascular, High cost, long duration No radiation exposure, Greatest diagnostic oncologic, ligamentous, of imaging, patient MRI can diagnose multiple Best accuracy for most bony infections, and comfort, not ideal if pathologies diagnoses children patient is unstable Superficial structures, No radiation exposure, gallbladder, fetal, cheap, fast, non-invasive, Very good in hands of US vascular, superficial None significant Dependent can be done at bedside, experienced sonographer infection, abdominal functional live images organs, trauma, heart Function of organs, Some diagnoses can only Radiation exposure, metabolic activity of be found on this type of Good for certain Nuclear Medicine expensive, special NA structures, perfusion of imaging, functional live diagnoses equipment, slow organs, many others. images can be obtained  UNDERSTAND SAFETY LIMITATIONS OF EACH IMAGING MODALITY  QUESTIONS References: Damian Cole DO FACEP Grainger & Allison's Diagnostic Radiology, Seventh [email protected] Edition Learning Radiology: Recognizing the Basics, Fourth Edition Radiopaedia.org