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Radiology Np Students2 Radiology Np Students2 Presentation Transcript

  • Joshua Daniel Hanelin, MD
  • OVERVIEW I. Why Radiology II. Cost III. Radiation Dose IV. Imaging Modalities, Physics, and Contrast Reactions V. Organ Based Approach to Imaging VI. How to Order an Exam
  • WHY RADIOLOGY?
  • WHY RADIOLOGY? Specific Question vs Fishing Expedition: Tailor your study to answer the question.  Does my patient have gallstones?  Does my patient have a kidney stone?  Does my patient have a small bowel obstruction?  Does my patient have fibroids? Vs  Why does my patient have this vague abdominal pain?  Why does my patient have a fever?  Why does my patient have knee pain?
  • COST  Radiographs: $30 - $80  Ultrasound: $120 - $160  CT: $300 - $2000  Nuclear scans: $120 - $240  MRI: $670 - $1,250  PET-CT: > $3,000  Current expenditures on all medical imaging: $100 billion per year  Growth rate: doubling every decade
  • RADIATION DOSE
  • RADIATION DOSE  Chest X-ray: 0.05 mSv  Extremity X-ray: 0.1 mSv  Abdomen X-ray: 1.0 mSv  Head CT: 1 mSv  Bone scan: 5 mSv  Abd. Fluoro (e.g. barium enema): 5-15 mSv  Abdomen CT: 10-20 mSv
  • RADIATION DOSE  100 mSv to each of 100 adults yields about 1 extra malignancy  Dose from a single abdomen CT minimally – but definitely – increases cancer risk  Age at exposure is crucial
  • RADIATION DOSE  Chest X-ray: 0.05 mSv  Extremity X-ray: 0.1 mSv  Abdomen X-ray: 1.0 mSv  Head CT: 1 mSv  Bone scan: 5 mSv  Abd. Fluoro (e.g. barium enema): 5-15 mSv  Abdomen CT: 10-20 mSv
  • RADIATION DOSE Brenner D, Elliston C, Hall E, Berdon W. Estimated Risks of Radiation- Induced Fatal Cancer from Pediatric CT. AJR 2001;176:289–296.
  • RADIATION DOSE  Belly exams are the big-dose ones  If you can avoid a few hundred per career, you’ll probably avoid causing a cancer  Still - for any serious disease, failure to diagnose is still more dangerous than the radiation.
  • WHY RADIOLOGY? Always ask yourself: Will the results of this test change my management of the patient? Is this cost effective? Are the risks worth the benefit?
  • Conventional Radiography Image Generation:  X ray – Electromagnetic radiation
  • Conventional Radiography EQUIPMENT
  • Conventional Radiography FILM RADIOGRAPHY
  • Conventional Radiography FILM RADIOGRAPHY
  • Conventional Radiography FILM RADIOGRAPHY
  • Conventional Radiography COMPUTED RADIOGRAPHY
  • Conventional Radiography DIGITAL RADIOGRAPHY
  • Conventional Radiography CONVENTIONAL TOMOGRAPHY
  • Conventional Radiography CONVENTIONAL TOMOGRAPHY
  • Conventional Radiography FLUOROSCOPY
  • Conventional Radiography FLUOROSCOPY
  • CONVENTIONAL RADIOGRAPHY FLUOROSCOPY Contrast Agents: Barium Sulfate – Well tolerated. Aspiration rarely causes a clinical problem. Major risk is barium peritonitis due to spill into peritoneal cavity through bowel perforations. Water-soluble iodinated contrast media – No risk of peritonitis. Aspiration causes chemical pneumonitis. Large volumes in the GI tract draw water into the gut and may lead to hypovolemia, shock, and death.
  • Conventional Radiography CONVENTIONAL ANGIOGRAPHY
  • Conventional Radiography RADIOGRAPHIC VIEWS  Beam Direction:  Posteroanterior (PA)  Anteroposterior (AP)  Craniocaudad(CC)  Patient Position:  Erect  Supine  Prone  Lateral Decubitus  Obliques
  • Conventional Radiography PRINCIPLES OF INTERPRETATION  5 basic radiographic densities:  Air – little attenuation  Fat – intermediate attenuation  Soft tissue – intermediate attenuation  Bone – high attenuation  Metal/Contrast agents – high attenuation
  • Conventional Radiography PRINCIPLES OF IMAGE INTERPRETATION  Structures are seen when outlined by tissues of different xray attenuation
  • CROSS-SECTIONAL IMAGING IMAGING PLANES
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY  Computer reconstruction of cross section of body from measurements of x-ray transmission through thin slices of the patient
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY  Conventional CT  Images obtained one slice at a time  Helical/Spiral CT  Patient table moves while xray tube rotates around patient  Multidetector helical CT  Multiple detectors allowing multiple slices per rotation of the xray tube
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Contrast:  Intravenous – Enhance density differences between lesions and surrounding parenchyma, demonstrate vascular anatomy, and characterize lesions by patterns of contrast enhancement  Oral – Required to opacify the bowel to help differentiate between from tumors, lymph nodes, and hematomas
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Contrast Reactions:  Mild – nausea, vomiting, urticaria, injection site warmth, injection site pain Tx: Observation 20 – 30 minutes  Moderate – hives, vasovagal reactions, bronchospasm, mild laryngeal edema Tx: Diphenhydramine, beta-agonists, epinephrine, leg elevation  Severe – severe bronchospasm, severe laryngeal edema, loss of consciousness, seizures, cardiac arrest Tx: Life support equipment and CPR
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Local adverse contrast effects: venous thrombosis, extravasation of contrast with associated pain, edema, skin slough, or deeper tissue necrosis Tx: elevate limb, warm compresses, consider plastic surgery consult
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Contrast-induced Nephropathy  Acute renal failure within 48 hours of contrast administration  Possibility of permanent renal damage  Risk factors: diabetes and chronic renal insufficiency  Prevention: Adequate hydration, administration of N- acetylcysteine, use of Visipaque  Chronic dialysis patients at risk for adverse effect of osmotic load and direct toxicity on heart; recommend dialysis on day of contrast administration
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Metformin  Oral antihyperglycemic used for type 2 DM  May precipitate fatal lactic acidosis in presence of renal impairment  FDA recommends withholding metformin for 48 hrs following administration of IV contrast and reinstated only after renal function has been reevaluated and found to be normal
  • CROSS-SECTIONAL IMAGING COMPUTED TOMOGRAPHY Patients at risk for adverse reactions:  Reassess need for IV contrast and consider diagnostic alternatives  Previous history of adverse reaction  History of asthma or allergies: Iodine? Shellfish?  Cardiac dysfunction: CHF, arrhythmias, unstable angina, recent MI, pulmonary HTN  Renal insufficiency  Diabetes  Sickle cell disease  Multiple Myeloma  Age over 55 yrs
  • CROSS SECTIONAL IMAGING COMPUTED TOMOGRAPHY Premedication regimens:  Prednisone 50 mg orally taken at 13, 7, and 1 hour prior to contrast administration. Diphenhydramine 50 mg orally, IV, or intramuscularly at 1 hour prior to contrast. Use nonionic low-osmolality agent.  Methylprednisolone 32 mg orally at 12 and 2 hours prior to contrast administration. Use of diphenhydramine is optional. Nonionic low-osmolality agent should be used.
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING  Based on the ability of protons in the body to absorb and emit radio wave energy when the body is placed in a strong magnetic field  Multiple different pulse sequences used to emphasize different tissue characteristics  Advantages: excellent soft tissue contrast resolution, provides images in any plane, absence of ionizing radiation  Limitations: Inability to demonstrate dense bone detail or calcifications, long imaging times, limited spatial resolution compared with CT, expensive
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING Intravenous contrast: Enhance differences between lesions and surrounding parenchyma, demonstrate vascular anatomy, and characterize lesions by patterns of contrast enhancement  Adverse reactions (rare): nausea, vomiting, headache, injection site warmth, paresthesias, dizziness, itching  No nephrotoxicity Oral contrast: Not used
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING Nephrogenic Systemic Fibrosis (NSF)  Rare disorder affecting patients with renal impairment after receiving intravenous MRI contrast agents  Fibrosis of skin, joints, eyes, and internal organs  Constant pain, muscle restlessness, and loss of skin flexibility  No consistently effective therapy  Avoid MRI contrast agents if GFR < 30
  • CROSS-SECTIONAL IMAGING MAGNETIC RESONANCE IMAGING Nephrogenic Systemic Fibrosis (NSF)
  • CROSS-SECTIONAL IMAGING ULTRASONOGRAPHY  Ultrasound transducer converts electrical energy to a pulse of high frequency sound energy, which reflects off of tissues, producing echoes which are used to generate images.  Real time imaging of moving patient tissue  Doppler ultrasound permits detection of blood velocity and direction  Highly operator dependent
  • CROSS-SECTIONAL IMAGING ULTRASONOGRAPHY
  • CROSS-SECTIONAL IMAGING NUCLEAR MEDICINE External detection and mapping of the biodistribution of radiotracers that have been administered to a patient. Poor spatial resolution, but high functional resolution. Examples: Ventilation perfusion scan, bone scan, biliary scan, white blood cell scan, renal scan, thyroid scan, brain scan, PET, liver spleen scan
  • CROSS-SECTIONAL IMAGING NUCLEAR MEDICINE
  • NEUROLOGIC IMAGING: BRAIN General rule: CT for acute neurologic illness (< 48 hrs); MRI for chronic neurologic illness (> 3 days), never use plain films If the CT or MRI suggests:  Vascular lesion MR or CT angiogram  Tumor Contrast  No infarct, but Sx of infarct Carotid doppler US or MRA or CTA Acute Trauma CT with no contrast MR I inappropriate: multisystem trauma, assisted ventilation Sedation for agitated adults and children
  • NEUROLOGIC IMAGING: BRAIN SPECIFIC SITUATIONS Acute Trauma: Noncontrast CT Stroke: Noncontrast CT followed by MRI Seizure: 1st Seizure, contrast-enhanced MR or CT Postictal state or residual neurologic deficit, Noncontrast CT Chronic seizure disorder, detailed MRI Infection and Cancer: contrast-enhanced MRI Headache: Acute headache, noncontrast CT Chronic headache with no neurologic Sx, noncontrast MRI Chronic headache with neurologic Sx, contrast-enhanced MRI Dementia: noncontrast MRI
  • NEUROLOGIC IMAGING: BRAIN XX, best study; X acceptable study (depending on situation)
  • NEUROLOGIC IMAGING: SPINE Acute Trauma: Plain film, CT if plain film findings equivocal Everything else: MRI
  • HEAD AND NECK IMAGING CT vs MRI CT: Patient cannot hold still, obstructed salivary ducts, fractures MRI: Discrimination of soft tissue pathology
  • THORACIC IMAGING Mainstay: Posteroanterior (PA) and lateral chest radiographs Special views:  Lateral decubitus: Small effusions or small pneumothorax  Expiratory radiograph: Focal or diffuse air trapping  Apical lordotic view: Visualization of lung apices  Chest fluoroscopy: Diaphragmatic paralysis
  • THORACIC IMAGING
  • THORACIC IMAGING
  • THORACIC IMAGING
  • THORACIC IMAGING PET: Oncologic diagnosis and staging Ventilation/Perfusion Lung Scan: Diagnosis of PE `
  • LIVER  Contrast-enhanced multidetector CT (MDCT): Primary imaging method  MRI with contrast: Inability to give iodinated contrast or need for multiple repeat examinations  US: Screening method for patients with abdominal symptoms and suspected diffuse or focal liver disease, assessment of hepatic vessels
  • BILIARY TREE  US: Screening for biliary obstruction  MRCP: High resolution imaging of biliary tree
  • GALLBLADDER US: Method of choice Cholescintigraphy: Equivocal ultrasound for detection of acute cholecystitis
  • PANCREAS AND SPLEEN PANCREAS: Contrast enhanced multidetector CT vs contrast enhanced MRI US poor visualization of pancreas SPLEEN: Contrast enhanced CT and US
  • PHARYNX AND ESOPHAGUS Barium Swallow/Esophagram: Swallowing disorders and mucosal lesions CT: Cancer staging, extent of disease MR: Cancer staging, extent of disease, preferred for evaluation of nasopharynx
  • STOMACH AND DUODENUM Upper GI Series (UGI): Evaluation of mucosal surface, largely being replaced by endoscopy CT: Extraluminal component of disease
  • SMALL BOWEL Small Bowel Follow Through (SBFT): Insensitive, bowel lumen and mucosa details Enteroclysis: Improved anatomic detail, shorter imaging time CT: Extraluminal disease
  • ADRENAL GLANDS AND KIDNEYS ADRENAL GLANDS CT: Modality of choice MRI: High quality images with ability to differentiate benign adrenal adenomas
  • ADRENAL GLANDS AND KIDNEYS KIDNEYS Contrast enhanced MDCT: Modality of choice MRI: Patients who cannot tolerate iodinated IV contrast US: Screening study to detect hydronephrosis and demonstrate kidney size
  • PELVICALYCEAL SYSTEM AND URETERS Contrast enhanced MDCT: Modality of choice MRI with or without contrast: Patients who cannot tolerate iodinated IV contrast or with poor renal function
  • BLADDER Cystogram: Detailed examination of bladder mucosa CT or MRI: Cancer staging
  • URETHRA Retrograde urethrogram: Anterior male urethra Voiding cystourethrogram: Anterior and posterior urethra
  • GENITAL TRACT FEMALE GENITAL TRACT US: Primary imaging modality; Transvaginal vs Transabdominal CT/MRI: Staging and follow up of pelvic malignancies Hysterosalpingography (HSG): Congenital anomalies and causes of infertility
  • GENITAL TRACT TESTES AND SCROTUM Color US: Primary imaging method CT/MRI: Tumor staging and locating undescended testes
  • GENITAL TRACT PROSTATE AND SEMINAL VESICLES MR with endorectal coil: Local disease staging CT/MRI: Nodal disease and distant spread
  • MUSCULOSKELETAL Plain Radiograph: Minimum of two films at 90 degrees to each other CT: Examination of fine bony details or high suspicion of fracture not seen on plain radiograph MRI: Extent of tumor, characterization of soft tissues, radiographically occult fractures
  • ORDERING AN EXAM  Ask for exams sequentially rather than all at once  Use your radiologists  Train your radiologists  Help your radiologists
  • ORDERING AN EXAM
  • WHEN IN DOUBT ASK YOUR LOCAL RADIOLOGIST
  • THAT’S IT AND THAT’S ALL G’BYE Y’ALL!
  • Questions, Comments, Concerns… Joshua D Hanelin, MD jdhnyc14@yahoo.com