Pams 626 Orientation

PAMS 626 Essentials of Radiology Matthew Chanin, M.D.

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Objectives ƒ Develop an understanding of imaging modalities ƒ Learn radiographic anatomy ƒ Identify significant pathology on plain x-rays (radiographs) ƒ Appropriately utilize imaging examinations

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Course ƒ ƒ ƒ ƒ

Lectures and film interpretation Pop quizzes “Hot” seat approach Mid-term and final- 50/50

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Assumptions ƒ Basic knowledge of anatomy ƒ Outside reading – Squires – Mettler’s- Essentials of Radiology (optional)

ƒ Class participation ƒ Excellent night vision – book light 9/15/08

What is Radiology (Diagnostic Imaging)? Or why are you here?

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Patient Wellness

Intervention

Imaging

Labs

History and Physical

Patient’s Illness 9/15/08

Goal of Imaging ƒ Appropriate examinations – Most effective test to answer the clinical question – Patient able to cooperate with the exam

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Least cost Timely Minimize risks 9/15/08

Imaging Modalities ƒ ƒ ƒ ƒ ƒ

Plain x-ray (plain film) (radiograph) Ultrasound Computed tomography (CT) Magnetic Resonance Imaging (MRI) Nuclear Medicine

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Plain X-ray (films) ƒ Creates an image using x-rays – Images captures on film or digitally

ƒ Advantages – Readily available – Less expensive

ƒ Disadvantages – – –

Risk of ionizing radiation Many studies are insensitive, i.e. abdominal (KUB) films May delay definitive examination

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X-ray tube

Collimator

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X-ray tube patient

Analog cassettecontains film

Exposed film

Developed film

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Analog film development

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Analog cassette

X-ray tube patient Digital cassette (no film) Laser reader Digital image to PACS workstation

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Digital copy sent to archive for storage

Digital film processing and interpretation on a Picture Archiving and Communication System (PACS)

Common Plain Film Exams

Chest Musculoskeletal

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Abdomen

Common Plain Film Indications ƒ Chest – – –

? Pneumonia ? Trauma ? Mass

ƒ Musculoskeletal – ? Trauma – ? Arthritis

ƒ Abdomen – ? Bowel obstruction – ? Perforated bowel (free air) 9/15/08

Risk of Ionizing Radiation ƒ X-rays cause ionizations in living cells ƒ Ionizations remove electrons form atoms creating ions ƒ Ions interact with and possibly damage DNA ƒ Cells can repair some damage ƒ Higher x-ray doses can cause cell death or cell mutation (cancer) ƒ Dividing cells at greater risk- pregnant patients and children ƒ Effects are additive and cumulative over the patients lifetime 9/15/08

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Imaging the Pregnant Patient ƒ No plain films or CT of the abdomen, pelvis, lumbar spine or hips unless clearly medically indicated ƒ Order ultrasound or MRI examinations if possible ƒ Contact the Radiologist before beginning imaging workup

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Radiation Protection for the Health Care Worker ƒ Time – Limit time in a radiation producing area

ƒ Shielding – Wear a lead apron

ƒ Distance – Single greatest source of x-ray exposure to the health care worker is scatter radiation from the patient

ƒ Radiation monitoring badge may be required 9/15/08

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Contrast Administration ƒ Contrast allows identification of normal structures not normally seen on plain films ƒ Contrast also helps identify pathology ƒ Intravascular contrast- into blood – – –

Intravenous pyelogram (IVP) CT MRI

ƒ Intraluminal contrast- into gut – – – –

Upper Gastrointestinal (UGI) exams Small Bowel Follow through (SBFT) Barium Enema (BE) CT

ƒ Patients usually require a prep and pre-procedure labs 9/15/08

Intravascular Contrast ƒ ƒ ƒ

Tri-iodinated benzene ring 90+ percent renal excretion Complications include – Allergy – Renal insufficiency/failure ƒ Especially diabetics

– Cardiovascular abnormalities – Potential lactic acidosis in diabetic patients taking Glucophage (Metformin), discontinue before scan and for 48 hours after scan

ƒ Patients require pre-procedure BUN, Cr 9/15/08

Pre-Medication Recommendations ƒ History of “contrast allergy” ƒ If prior contrast reaction was severe, i.e. breathing difficulty consider another test and/or consult the radiologist ƒ Prednisone, 50 mg PO at 13 hr, 7 hr, and 1 hr before scan ƒ Diphenhydramine (Benadryl), 50 mg PO, 1 hr before scan

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MR Contrast ƒ ƒ

Gadolinium Gadolinium compound accumulates in abnormal tissues such as scar tissue and tumors, so they become brighter in MRI scans ƒ Passed out of the body in urine-rarely gadoliniumbased contrast agents can cause acute renal failure in patients with underlying chronic renal insufficiency ƒ Reactions are rare but can be life-threatening 9/15/08

Intra-luminal Contrast ƒ Barium – Administered orally or per rectum – Different concentrations – Usually well tolerated – Few complications

ƒ Water soluble contrast – Used with suspected perforation

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Abdomen without intravascular contrast

Abdomen with intravascular contrast

Abdomen without Intraluminal contrast

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Abdomen with Intraluminal contrast (UGI)

Ultrasound ƒ ƒ

Creates an image with sound waves Prep usually required – NPO for abdominal studies- optimize gallbladder distention – Force fluids (bladder distention) for pelvic ultrasound to aid in organ visualization

ƒ Advantages – – – –

NO ionizing radiation Portable and noninvasive (almost) Fast, useful in screening trauma patients Guide interventions- para/thoracentesis

ƒ Disadvantages – – –

Requires a skillful operator Anatomy is complex Patient size can limit study

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Ultrasound ƒ Images can be recorded on film or sent to a PACS workstation

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Common Ultrasound Exams and Indications ƒ

Abdominal (RUQ, renal etc.) – – – – – –

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Pelvic – – –

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? Torsion Evaluate mass

Vascular –

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? Ectopic pregnancy Vaginal bleeding ? ovarian pathology

Testicular – –

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? Gallstones or biliary tract disease Evaluate organ size Screen for masses Look for fluid (ascites) ? Hydronephrosis Evaluate aorta for aneurysm

? Stenosis or occlusion

Cardiac-Echocardiography (Cardiology) –

? Cardiac or valvular function

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Fetal Ultrasound 9/15/08

Intracavitary

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Different Ultrasound Transducers

Doppler Ultrasound ƒ Method to evaluate blood flow ƒ Usually displayed in color

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Computed Tomography (CT) ƒ Cornerstone of imaging the acute abdomen, trauma and cancer patient ƒ Images can be filmed or interpreted on a PACS workstation ƒ Advantages – Displays data in thin sections allowing for multiplanar reconstruction – Fast – Numerous software programs available for data analysis

ƒ Disadvantages – – – –

Ionizing radiation-LOTS! Frequently over utilized Many scans require intravascular contrast Unstable patients need close monitoring

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CT Scanner

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Common CT Exams and Indications ƒ Head – ? Stroke, bleed

ƒ Chest – ? Mass – ? Trauma – ? Pulmonary embolism

ƒ Abdomen/Pelvis – ? Appendicitis, renal stone, diverticulitis, bowel obstruction – ? Mass – ? Trauma

ƒ Musculoskeletal – Characterize fractures 9/15/08

Abdominal CT without contrast

Abdominal CT with intravascular and intraluminal contrast 9/15/08

(Axial)

Planes of imaging 9/15/08

Axial (transaxial)

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Coronal

Sagittal

Examples of CT image multiplanar reformation (MPR)

Advanced CT Techniques ƒ CT angiography (CTA) – Minimally invasive (requires IV and contrast injection) method to evaluate vascular anatomy/pathology

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Abdominal aortic aneurysm displayed on 3D workstation

Heart

Extremities 9/15/08

Aorta and kidneys

Examples of CTA

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CT- Virtual Colonoscopy

Radiation Dose Selected Procedures-Compared to Standard Chest X-ray Examination Chest X-ray

Effective Dose relative to a Chest X-ray 1 (0.1 mSv)

CT Abdomen/pelvis

160+

BE

80

Ultrasound

0

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Radiation Warning ƒ Controversial but increase in cancer risk is thought to occur with approximately 1,000 chest x-ray equivalent ƒ Radiation effects are additive over patients lifetime 9/15/08

Magnetic Resonance Imaging (MRI) ƒ Creates images with a strong magnetic field and radio waves ƒ Images can be filmed or sent to a PACS workstation for reading ƒ Advantages – Superior resolution of soft tissues including brain, spinal cord and joint anatomy – Helps characterize abdominal masses – No ionizing radiation, yet not FDA approved for routine fetal imaging – Multiplanar imaging standard 9/15/08

MRI ƒ Disadvantages – Ferromagnetic metals, i.e., aneurysm clips, older heart valves cannot be scanned – Patients with implanted devices, i.e., pacemakers, infusion pumps cannot be scanned – Serious risks to patients if proper safety precautions are not followed – Long scan times – Magnetic bore can induce patient claustrophobia – Loud “banging” noises during image acquisition requires patients to wear ear plugs – Patients with a history of welding or metal grinding may require preMRI orbit films

ƒ Most MRI centers have a lengthy pre-MRI check list 9/15/08

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MRI machine 9/15/08

Common MRI Exams and Indications ƒ Brain – ? Stroke, mass

ƒ Chest – ? Aortic dissection, vascular abnormality

ƒ Abdomen – ? Mass

ƒ Musculoskeletal – ? Ligamentous injury 9/15/08

Head coil/sagittal MRI

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Knee coil/sagittal MRI

Advanced MRI Techniques ƒ MR angiography (MRA) – Noninvasive evaluation of vessels

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MR Spectroscopy ƒ Noninvasive method to determine chemical composition of select tissue

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Nuclear Medicine (NM) ƒ Image different organs by injecting different radioactive isotopes ƒ NM gamma camera detects and displays isotope distribution in the patient ƒ Therapeutic NM is the administration of radioactive isotopes to treat disease. – Iodine 131 to treat hyperthyroidism or thyroid cancer 9/15/08

NM ƒ Advantages – Images organ and cellular function – Provides complimentary information to compare with CT or other anatomic imaging studies – Therapeutic options

ƒ Disadvantages – – –

Patients and their bodily fluids become radioactive Some exams require days to complete Patient must be able to hold still for lengthy image acquisition

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Bone scan Gamma camera

Lung scan

Inject patient Renal scan

(different compound per exam)

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Common nuclear medicine exams

Hepatobiliary(DISIDA) scan

NM Single Photon Emission Computed Tomography (SPECT) ƒ Gamma camera rotates around patient and collects data from multiple points (much like a CT scanner) ƒ Data reconstructed into multiple different planes

Myocardial SPECT scan 9/15/08

NM Positron Emission Tomography (PET) ƒ Radioactive glucose injected into patient ƒ Most commonly used in imaging cancer patients ƒ Cardiac and neurological indications

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PET scanner 9/15/08

PET scan in patient with lung cancer

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PET/CT fusion

Radiology Charges ƒ Total charge is a combined professional and technical component ƒ Professional fee – Charge for image interpretation

ƒ Technical fee – All other costs including hospital/clinic fee, technologist salary, utilities and supplies

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Representative Charges Exam

Pro fee

Tech fee

Total

CXR

$29

$109

$138

UGI

$90

$253

$343

NM Bone

$113

$462

$575

NM PET

$201

$2958

$3159

MRI head

$193

$1382

$1575

CT head

$111

$583

$694

CT abd/pel

$316

$1654

$1970

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Image Interpretation ƒ MUST know normal radiographic anatomy including different projections ƒ MUST have an approach to film interpretation ƒ MUST know radiographic appearance of common and life threatening diseases ƒ MUST know appropriate utilization and limitations of each imaging modality ƒ MUST understand radiographic terminology ƒ MUST know ones own limitations 9/15/08

Different Radiographic Densities (Different degrees of photon absorption) ƒ ƒ ƒ ƒ ƒ ƒ

Soft tissue Fat Air Bone Contrast Material Foreign material- metal

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Air

Fat Soft tissue (spleen) Bone

CT Densities 9/15/08

Soft tissue (liver) Air

Fat Bone

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Radiographic density of abnormality helps determine the differential diagnosis