Radiology Np Students2

transcript

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 RadiographyCOMPUTED RADIOGRAPHY

Conventional RadiographyDIGITAL RADIOGRAPHY

Conventional RadiographyCONVENTIONAL TOMOGRAPHY

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

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

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

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

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

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

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

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

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

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 IMAGINGPET: Oncologic diagnosis and staging

Ventilation/Perfusion Lung Scan: Diagnosis of PE

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, MDjdhnyc14@yahoo.com

Radiology Np Students2

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