Radiology Np Students2
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Transcript of Radiology Np Students2
Radiology for the Non Radiologist
Joshua Daniel Hanelin, MD
OVERVIEWI. Why RadiologyII. CostIII. Radiation DoseIV. Imaging Modalities, Physics, and Contrast
ReactionsV. Organ Based Approach to ImagingVI. 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?VsWhy does my patient have this vague abdominal pain?Why does my patient have a fever?Why does my patient have knee pain?
COSTRadiographs: $30 - $80Ultrasound: $120 - $160CT: $300 - $2000Nuclear scans: $120 - $240MRI: $670 - $1,250PET-CT: > $3,000
Current expenditures on all medical imaging: $100 billion per year
Growth rate: doubling every decade
RADIATION DOSE
RADIATION DOSEChest X-ray: 0.05 mSvExtremity X-ray: 0.1 mSvAbdomen X-ray: 1.0 mSvHead CT: 1 mSvBone scan: 5 mSvAbd. Fluoro (e.g. barium enema): 5-15 mSvAbdomen CT: 10-20 mSv
RADIATION DOSE100 mSv to each of 100 adults yields about 1
extra malignancyDose from a single abdomen CT minimally –
but definitely – increases cancer riskAge at exposure is crucial
RADIATION DOSEChest X-ray: 0.05 mSvExtremity X-ray: 0.1 mSvAbdomen X-ray: 1.0 mSvHead CT: 1 mSvBone scan: 5 mSvAbd. Fluoro (e.g. barium enema): 5-15 mSvAbdomen 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 DOSEBelly exams are the big-dose onesIf you can avoid a few hundred per career,
you’ll probably avoid causing a cancerStill - 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 RadiographyImage Generation:X ray – Electromagnetic radiation
Conventional RadiographyEQUIPMENT
Conventional RadiographyFILM RADIOGRAPHY
Conventional RadiographyFILM RADIOGRAPHY
Conventional RadiographyFILM RADIOGRAPHY
Conventional RadiographyCOMPUTED RADIOGRAPHY
Conventional RadiographyDIGITAL RADIOGRAPHY
Conventional RadiographyCONVENTIONAL TOMOGRAPHY
Conventional RadiographyCONVENTIONAL TOMOGRAPHY
Conventional RadiographyFLUOROSCOPY
Conventional RadiographyFLUOROSCOPY
CONVENTIONAL RADIOGRAPHYFLUOROSCOPY
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 RadiographyCONVENTIONAL ANGIOGRAPHY
Conventional RadiographyRADIOGRAPHIC VIEWSBeam Direction: Posteroanterior (PA) Anteroposterior (AP) Craniocaudad(CC)
Patient Position: Erect Supine Prone Lateral Decubitus Obliques
Conventional RadiographyPRINCIPLES OF INTERPRETATION5 basic radiographic densities:Air – little attenuationFat – intermediate attenuationSoft tissue – intermediate attenuationBone – high attenuationMetal/Contrast agents – high attenuation
Conventional RadiographyPRINCIPLES OF IMAGE INTERPRETATIONStructures are seen when outlined by tissues
of different xray attenuation
CROSS-SECTIONAL IMAGINGIMAGING PLANES
CROSS-SECTIONAL IMAGINGCOMPUTED TOMOGRAPHYComputer reconstruction of cross section of
body from measurements of x-ray transmission through thin slices of the patient
CROSS-SECTIONAL IMAGINGCOMPUTED TOMOGRAPHY
Conventional CT Images obtained one slice at a time
Helical/Spiral CTPatient table moves while xray tube rotates around
patient
Multidetector helical CTMultiple detectors allowing multiple slices per rotation
of the xray tube
CROSS-SECTIONAL IMAGINGCOMPUTED 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 IMAGINGCOMPUTED TOMOGRAPHY
CROSS-SECTIONAL IMAGINGCOMPUTED 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 IMAGINGCOMPUTED 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 IMAGINGCOMPUTED TOMOGRAPHY
Contrast-induced NephropathyAcute renal failure within 48 hours of contrast
administrationPossibility of permanent renal damageRisk factors: diabetes and chronic renal insufficiencyPrevention: Adequate hydration, administration of N-
acetylcysteine, use of VisipaqueChronic dialysis patients at risk for adverse effect of
osmotic load and direct toxicity on heart; recommend dialysis on day of contrast administration
CROSS-SECTIONAL IMAGINGCOMPUTED TOMOGRAPHY
Metformin
Oral antihyperglycemic used for type 2 DMMay precipitate fatal lactic acidosis in presence
of renal impairmentFDA 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 IMAGINGCOMPUTED TOMOGRAPHY
Patients at risk for adverse reactions:Reassess need for IV contrast and consider diagnostic
alternativesPrevious history of adverse reactionHistory of asthma or allergies: Iodine? Shellfish?Cardiac dysfunction: CHF, arrhythmias, unstable angina, recent
MI, pulmonary HTNRenal insufficiencyDiabetesSickle cell diseaseMultiple MyelomaAge over 55 yrs
CROSS SECTIONAL IMAGINGCOMPUTED 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 IMAGINGMAGNETIC 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 IMAGINGMAGNETIC RESONANCE IMAGING
CROSS-SECTIONAL IMAGINGMAGNETIC RESONANCE IMAGING
CROSS-SECTIONAL IMAGINGMAGNETIC 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 IMAGINGMAGNETIC 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 organsConstant pain, muscle restlessness, and loss of
skin flexibilityNo consistently effective therapyAvoid MRI contrast agents if GFR < 30
CROSS-SECTIONAL IMAGINGMAGNETIC RESONANCE IMAGING
Nephrogenic Systemic Fibrosis (NSF)
CROSS-SECTIONAL IMAGINGULTRASONOGRAPHY
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 tissueDoppler ultrasound permits detection of blood
velocity and directionHighly operator dependent
CROSS-SECTIONAL IMAGINGULTRASONOGRAPHY
CROSS-SECTIONAL IMAGINGNUCLEAR 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 IMAGINGNUCLEAR MEDICINE
NEUROLOGIC IMAGING: BRAINGeneral 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 angiogramTumor ContrastNo infarct, but Sx of infarct Carotid doppler US or MRA
or CTA
Acute Trauma CT with no contrastMR I inappropriate: multisystem trauma, assisted ventilation
Sedation for agitated adults and children
NEUROLOGIC IMAGING: BRAINSPECIFIC 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: SPINEAcute Trauma: Plain film, CT if plain film
findings equivocal
Everything else: MRI
HEAD AND NECK IMAGINGCT vs MRI
CT: Patient cannot hold still, obstructed salivary ducts, fractures
MRI: Discrimination of soft tissue pathology
THORACIC IMAGINGMainstay: Posteroanterior (PA) and lateral
chest radiographs
Special views:Lateral decubitus: Small effusions or small
pneumothoraxExpiratory radiograph: Focal or diffuse air
trappingApical lordotic view: Visualization of lung
apicesChest fluoroscopy: Diaphragmatic paralysis
THORACIC IMAGING
THORACIC IMAGING
THORACIC IMAGING
THORACIC IMAGINGPET: 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 obstructionMRCP: High resolution imaging of biliary tree
GALLBLADDER
US: Method of choice
Cholescintigraphy: Equivocal ultrasound for detection of acute cholecystitis
PANCREAS AND SPLEENPANCREAS: Contrast enhanced multidetector
CT vs contrast enhanced MRI
US poor visualization of pancreas
SPLEEN: Contrast enhanced CT and US
PHARYNX AND ESOPHAGUSBarium 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 DUODENUMUpper GI Series (UGI): Evaluation of mucosal
surface, largely being replaced by endoscopy
CT: Extraluminal component of disease
SMALL BOWELSmall Bowel Follow Through (SBFT):
Insensitive, bowel lumen and mucosa
details
Enteroclysis: Improved anatomic detail, shorter imaging time
CT: Extraluminal disease
ADRENAL GLANDS AND KIDNEYSADRENAL GLANDS
CT: Modality of choice
MRI: High quality images with ability to differentiate benign adrenal adenomas
ADRENAL GLANDS AND KIDNEYSKIDNEYS
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 TRACTFEMALE 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 TRACTTESTES AND SCROTUM
Color US: Primary imaging method
CT/MRI: Tumor staging and locating undescended testes
GENITAL TRACTPROSTATE AND SEMINAL VESICLES
MR with endorectal coil: Local disease staging
CT/MRI: Nodal disease and distant spread
MUSCULOSKELETALPlain 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 EXAMAsk for exams sequentially rather than all at
onceUse your radiologistsTrain your radiologistsHelp your radiologists
ORDERING AN EXAM
WHEN IN DOUBTASK YOUR LOCAL RADIOLOGIST
THAT’S IT AND THAT’S ALL
G’BYE Y’ALL!
Questions, Comments, Concerns…
Joshua D Hanelin, [email protected]