Preclerkship Imaging Module

Introduction to Radiographic Imaging

for the Pre-clerkship Student

Let's go!

Introduction

Click through this interactive module to learn about different imaging modalities used to diagnose several common pathologies that you may encounter in the hospital. Helpful Tip: Every image is enlargable AND is linked to a direct case from Radiopaedia! Feel free to explore more on that resource where you can actually scroll through the CTs and MRIs.

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Table of Contents

MODULES

OBJECTIVES

ASSESSMENT

Objectives

• Become familiar with the basic mechanics behind x-ray, CT, and MRI
• Be able to identify normal X-ray, CT, and MRI imaging
• Be able to identify common pathologies on x-ray, CT, and MRI imaging
• Understand the fundamentals, uses, and benefits of ultrasound

Modules

X-Ray

Ultrasound

MRI

CT

Module 1. Fundamentals of X-Ray

X-rays are two-dimensional images generated by mapping the attentuation of the x-rays as they pass through the body. Therefore different tissues will produce different densities on imaging:

Air

Fat

Soft Tissue

Lowest Density

Highest Density

Bone

Landmarks on a Normal Chest X-Ray

Hover over each marker to see reveal each label!

Method of Reading a Chest X-Ray Start with the ABCDEs: A: Airway - Is the trachea midline? - Is there evidence of a foreign body?B: Bones - Assess for fractures or other abnormalities of bony structures C: Cardiac - Evidence of cardiomegaly? D: Diaphragm - Blunting of costophrenic angles - Air under the diaphragmE: Everything else

Considerations for X-Ray

• Radiation exposure
• Allergy to contrast or iodine
• Pregnant patients
• Some x-ray tables may have weight limits

Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 8304

Common Chief Complaints:

Click each chief complaint to see more

Patient with chronic cough and 40-pack year smoking history

Patient with chronic cough and bloody sputum

Patient with fever, chills, and cough for 4 days

Patient with JVD, shortness of breath, hepatospleno-megaly, and pedal edema

Module 2. Fundamentals of CT

Computed tomography (CT) uses x-rays to create cross-sectional images of the body. The x-ray emiter rotates around the patient and detector in order to generate images using measurements of the transmission of x-ray through the body section. CT numbers are presented in Hounsfield Units (HU) to reflect the different x-ray densities in the human body:

Landmarks on a Normal CT Abdomen

Hover over each marker to see reveal each label!

For orientation, the image is produced as you would "see" it from the patient's feet while the patient is lying supine.

Note the hyperintensity of the fluid inside the bowel. This is due to the oral contrast given to the patient prior to the CT.

Considerations

• Radiation exposure
• Allergy to contrast or iodine
• Patients with renal insufficiency
• Pregnant patients
• Claustrophobia

Case courtesy of Andrew Dixon, Radiopaedia.org, rID: 36677

Common Chief Complaints:

Click each chief complaint to see more

Patient with severe abdominal pain, distention, and constipation

Patient with fever, jaundice, abdominal pain, and vomiting

Patient with acute lower abdominal pain radiating to the right side

Patient with burning with urination, increased urgency, and unilateral lower back pain

Module 3. Fundamentals of MRI

Magnetic resonance imaging (MRI) creates a strong, uniform magnetic field and radiofrequency pulses that result in a set of images. Depending on the sequence used and tissue being examined, the images will have a particular appearance.

DWI

Flair

T2

T1

Most common sequences used in clinical practice

MRI Sequences

Landmarks on a Normal Brain MRI

Hover over each marker to see reveal each label!

Considerations

• Sensitive to motion artifact
• Inferior to CT for acute hemorrhage
• Inferior to CT for bony injury
• Claustrophobia
• Allergy to contrast

Contraindications

• Implanted devices or metallic devices

Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 37605

Common Chief Complaints:

Click each chief complaint to see more

Patient with increased confusion, memory difficulties, and history of stroke

Patient with unexplained weight loss, blurry vision, and headaches

Patient with right sided weakness and aphasia for the past 5 hours

Patient with fatigue, unilateral double vision, and muscle spasms/stiffness

Module 4. Basic Fundamentals of US

How It Works

Uses

Benefits/Risks

• Uses high-frequency sound waves to view structures inside the body
• Ultrasound image is produced from the relfection of sound waves off of internal body structures

• No exposure to radiation
• Readily available bedside
• Can produce biological effects in the body

• e-FAST (Trauma)
• Breast ultrasound
• Doppler fetal heart rate monitoring
• Fetal ultrasounds
• Echocardiogram

• Ultrasound-guided biopsies or needle placement

Post-Test

Please keep an eye out for a future email with the link to the post-test!

Course completed!

We hope this information will be useful for you throughout your clerkships! 😊 We will send out a survey asking about your experience and any feedback at the end of your M1 year. Please be sure to fill that out, as it will be integral to evaluating the impact of this module! Completion of the pre-quiz, post-quiz, and survey are required to be entered into the raffle to win a $10 Starbucks gift card! Thank you!

Pneumonia

Infection of the parenchyma of the lung

Classic presentation: acute onset of fever, productive cough, dyspnea, and chest painMost common pathogens: Streptococcus pneumoniae, Haemophilus influenza, Moraxella catarrhalis, Staphylococcus aureus, group A Streptococcus Chest x-ray is best initial test Best initial treatment for empiric coverage: amoxicillin, tetracycline (e.g., doxycycline), macrolide

Tuberculosis (TB)

Caused by Mycobacterium tuberculosis Common presenting symptoms: cough, hemoptysis, dyspnea, fever, weight loss, night sweats, fatigue Primary tuberculosis: hilar nodes + Ghon focus (mid/lower lobes) Secondary tuberculosis (90%): healed primary infection with reactivation Progressive primary tuberculosis (10%):

• Secondary to immunosuppression
• Spreads within blood and causes miliary TB

Appendicitis

Inflammation and infection of the appendiceal lumen due to obstructionClassic presentation:

• Dull periumbilical pain with migration to sharp right lower quadrant pain
• Nausea, vomiting
• Anorexia
• Fever

Treatment: IV antibiotics with anaerobic and gram-negative coverage, NPO, IV fluids, +/- surgical intervention

Congestive Heart Failure (CHF)

Cardiac pump dysfunction causes congestion and low systemic perfusion Common symptoms/signs:

• Dyspnea
• Orthopnea
• Fatigue
• S3 heart sound
• Rales
• Jugular venous distention
• Pitting edema

Treatment is based on the severity The most common cause of right heart failure is left heart failure!

Chronic Obstructive Pulmonary Disease (COPD)

• Broad category of diseases with decreased lung function secondary to obstruction of airflow
• Two major subtypes: chronic bronchitis and emphysema
• Pulmonary Function Tests typically show:
• Decreased FEV1
• Normal or decreased FVC
• Decreased FEV1/FVC ratio (<70%)
• Air trapping in lungs can be seen as hyperinflated lungs on chest x-ray ("barrel chest")
• Most important risk factor is tobacco use

Cirrhosis

Progressive fibrosis of the liver causing organ dysfunction Clinical presentation is secondary to complications of portal hypertension: ascites, jaundice, hepatic encephalopathy, gastroesophageal varices, transudative pleural effusion, thrombocytopenia Treatment is largely supportive. All cirrhotic patients should receive vaccinations for hepatitis A, hepatitis B, and pneumonia.

MCA Stroke

with DWI

Two types of stroke: ischemic (80%) or hemorrhagic (20%) Symptoms are dependent on the vascular territory affected Distinguishing features of MCA stroke

• Contralateral paresis, sensory loss in the face and arm
• Contralateral homonymous hemianopsia
• Aphasia in the dominant hemisphere
• Neglect in non-dominant hemisphere

Case courtesy of Ian Bickle, Radiopaedia.org, rID: 46842

Multiple Sclerosis

with Flair

Chronic, demyelinating disorder of the CNS with unclear etiology Subtypes: relapsing-remitting, primary progressive, secondary progressive, progressive relapsing Symptoms are separate in time and space Classic clinical presentation: bilateral internuclear ophthalmoplegia, limb weakness, Lhermitte sign (sudden, brief, electric shock-like sensation that runs down the spine and into the arms and legs), blurry vision, GU dysfunction Treatment for acute exacerbations: high-dose IV corticosteroids, plasma exchange

Case courtesy of Ahmed Abdrabou, Radiopaedia.org, rID: 35195

Vascular Dementia

with T2

Type of dementia that is associated with a history of stroke or cerebrovascular disease Second most common type of dementia The time course typically presents as a stepwise, abrupt decline in cognitive function Risk factors: age, hypertension, diabetes, coronary artery disease, history of stroke Brain imaging will show old infarctions or deep white matter changes secondary to chronic ischemia

Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 25641

Small Bowel Obstruction (SBO)

Partial or complete blockage of the small intestineCauses: adhesions (most common cause), hernias, neoplasms, intussusception, gallstone ileus, stricture, and volvulus Clinical presentation: crampy, colicky abdominal pain with vomiting, distension of abdomen with tenderness, hyperactive bowel sounds Treatment: fluid resuscitation, treatment of underlying cause

Nephrolithiasis

Most common type of kidney stones is calcium oxalate stonesClinical presentation

• Acute onset of severe, colicky flank pain
• Nausea and vomiting
• Patients are unable to get comfortable and shift positions frequently

Noncontrast abdominal CT is the gold standard for diagnosis Treatment: hydration and pain management

Glioblastoma

with T2

Astrocyte origin (GFAP+) Pseudopalisading pleomorphic tumor cells Common symptoms include headache, seizure, and focal deficits The most common malignant primary brain tumor, progresses rapidly and often has a poor prognosis Characteristic imaging findings: "butterfly-shaped" tumor with central necrosis; crosses corpus callosum Treatment

• Surgical resection
• Radiation and/or chemotherapy

Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 7798