An Introduction to Radiology and Nuclear Medicine

By Iman Lozi, Noor Elshobaky and Rhys Thornett


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What this resource includes:

Neurology
Summary
Overviews in:
Quiz
Radiology
How It All WorksRespiratory
Gastrointestinal

Section 1: Radiology

What is Radiology?

General Terminology

Body Terminology

Abbreviations

Diagnostic Radiology

Interventional Radiology

Section 2: Respiratory

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Section 3: Gastrointestinal

Gastrointestinal imaging has five main imaging modalities:


Plain x-rayMRI scansBarium scansCT scansUltrasound

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Section 3: Gastrointestinal

RECAP: Which image below shows which imaging modality? Abdominal x-ray (AXR)Computed Tomography (CT)Barium studies

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Section 3: Gastrointestinal

RECAP: Which image below shows which imaging modality? Abdominal x-ray (AXR)Computed Tomography (CT)Barium studies

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Section 3: Gastrointestinal

RECAP: Label the following anatomy:

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Section 3: Gastrointestinal

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  1. Liver
  2. Kidneys
  3. Bladder
  4. Psoas muscle
  5. Tip of spleen
  6. Gallbladder

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Section 3: Gastrointestinal

Case 1:

A 52-year-old man presents to A&E with a 2-day history of abdominal pain, vomiting and constipation. He has no recent travel history, and his underlying medical conditions include well controlled type 1 diabetes and hypertension.

You are the F1 on duty. Which of the following imaging would you request?

A: Colonoscopy
B: CT scan
C: MRI abdomen & pelvis
D: Abdominal x-ray
E: Barium enema

Reveal answer

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Section 3: Gastrointestinal

Case 1:

A 52-year-old man presents to A&E with a 2-day history of abdominal pain, vomiting and constipation. He has no recent travel history, and his underlying medical conditions include well controlled type 1 diabetes and hypertension.

You are the F1 on duty. Which of the following imaging would you request?

A: Colonoscopy
B: CT scan
C: MRI abdomen & pelvis
D: Abdominal x-ray
E: Barium enema

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Section 3: Gastrointestinal

Case 1 (continued):


An abdominal x-ray was performed. The image is show below. Which of the following diagnoses is best supported by this image?
Case 1 (continued):


An abdominal x-ray was performed. The image is show below. Which of the following diagnoses is best supported by this image?

Reveal answer

A: Pneumoperitoneum
B: Large bowel obstruction
C: Small bowel obstruction
D: Chron's disease
E: Coeliac disease

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Section 3: Gastrointestinal

Case 1 (continued):


An abdominal x-ray was performed. The image is show below. Which of the following diagnoses is best supported by this image?

Reveal answer

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A: Pneumoperitoneum
B: Large bowel obstruction
C: Small bowel obstruction
D: Chron's disease
E: Coeliac disease

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Section 3: Gastrointestinal

Large Bowel Obstruction:


The cardinal signs of a large bowel obstruction include abdominal pain, vomiting, and unopened bowels. The appropriate initial modality for viewing an obstruction is an abdominal x- ray, as this allows clear view of dilated bowel loops. 

It is a large bowel obstruction and not small bowel due to the presence of haustra. The ileum poseses valvulae conniventes instead of haustra.

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Section 3: Gastrointestinal

Large Bowel Obstruction:


The cardinal signs of a large bowel obstruction include abdominal pain, vomiting, and unopened bowels. The appropriate initial modality for viewing an obstruction is an abdominal x- ray, as this allows clear view of dilated bowel loops. 

It is a large bowel obstruction and not small bowel due to the presence of haustra. The ileum poseses valvulae conniventes instead of haustra.

Haustra can be identified as their transverse lines do not cross the entire width of the bowel wall.

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Section 3: Gastrointestinal

EXAM TIP: Do not miss a closed loop large bowel obstruction!

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Section 3: Gastrointestinal

EXAM TIP: Do not miss a closed loop large bowel obstruction!

If the ileocaecal valve is competent and a patient develops large bowel obstruction (LBO), the colon will dilate and become very large, and it cannot decompress back into the small bowel (since the valve prevents backflow), so the colon will progressively get larger and larger and will eventually perforate.

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Section 3: Gastrointestinal

EXAM TIP: Do not miss a closed loop large bowel obstruction!

Essentially, aportion of the large bowel becomes closed proximally and distally, meaning it becomes gasless and keeps growing until it perforates.

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Section 3: Gastrointestinal

EXAM TIP: Do not miss a closed loop large bowel obstruction!

A closed loop large bowel obstruction can involve a blockage on both the proximal and distal ends of the colon.

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Section 3: Gastrointestinal

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Case 2: Signs of Extraluminal Gas (Pneumotosis intestinalis)

There are three main signs of extraluminal gas that can appear on imaging scans:

Rigler sign, Football sign, and Falciform sign

Click the 'Next' button below to learn more about these signs...

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Section 3: Gastrointestinal

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Case 2: Signs of Extraluminal Gas (Pneumotosis intestinalis)

Rigler sign: both sides of the bowel wall can be seen which also results in triangles of air

Football sign: pockets of air seen on either side of the abdomen

Falciform sign: the liver's falciform ligament is visible on AXR. This should not usually be the case with its thin fibrous structure that connects the anterior part of the liver to the ventral wall of the abdomen

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Section 3: Gastrointestinal

Football signRigler signFalciform sign

Check Your Answers!

Can you match the sign to the image?

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Section 3: Gastrointestinal

Football signRigler signFalciform sign

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Can you match the sign to the image?

Section 3: Gastrointestinal

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Section 3: Gastrointestinal

Case 3: Small Bowel Obstruction

A 24 year old man presents with constipation, abdominal pain and vomiting. He recently underwent abdominal surgery for a chronic condition. The X ray on the right was done. What is most likely to have caused this presentation?

Reveal answer

A: Acute flare up of chronic conditon
B: Adhesions from surgery
C: H. pylori
D: Colon cancer
E: Surgical site infection

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Section 3: Gastrointestinal

Case 3: Small Bowel Obstruction

A 24 year old man presents with constipation, abdominal pain and vomiting. He recently underwent abdominal surgery for a chronic condition. The X ray on the right was done. What is most likely to have caused this presentation?

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A: Acute flare up of chronic conditon
B: Adhesions from surgery
C: H. pylori
D: Colon cancer
E: Surgical site infection

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Section 3: Gastrointestinal

Case 3: Small Bowel Obstruction (continued)

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The most common cause of small bowel obstruction is adhesions. This is where two parts of ileum scar together.

If a short bowel obstruction is of chronic nature, the ileum will initially fill with gas but will eventually dilate the bowel and then become filled with fluid.

If this happens, a CT scan is the preferred imaging modality as x-rays do not show fluid well.

Section 4: Neurology

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Section 4: Neurology

So given that these two different imaging modalities are often used in neurology, how do doctors know which scan to use?
Here are some examples of which scans are used for common pathologies:

Usually, this decision depends on a combination of what pathology a patient has presented with coupled with the amount of time available (i.e. acute emergency vs. routine scan)

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Section 4: Neurology

Now that you know the basics of CT and MRI scans in neurology, let's pause and review some basic anatomy which you will already know.

One of the most common organs that regularly requires imaging in patients is the brain.
Label this image of the brain below as a review of basic brain anatomy:
Click the button below to view the answers...

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Section 4: Neurology

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Section 4: Neurology

The Frontal Lobe
        Functions:
  • Primary motor cortex
  • Short-term memory
  • Attention
  • Planning
  • Motivation

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Section 4: Neurology

The Parietal Lobe
        Functions:
  • Pain
  • Temperature
  • Proprioception

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Section 4: Neurology

The Temporal Lobe
        Functions:
  • Auditory processing
  • Contains limbic system for processing of memory and emotion
  • Contains Wernicke's area to allow for speech comprehension

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        Functions:
  • Visuospatial processing
  • Distance and depth perception
  • Colour determination
  • Object and facial recognition

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The Occipital Lobe

Section 1: Radiology

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Section 1: Radiology

Diagnostic Radiology

  • Diagnostic radiology refers to the use of imaging devices for the sole purpose of capturing images of bodily organs underneath the skin in order to detect the presence of pathology and diagnose a disease
  • Often times, being able to physically see the presence of a disease inside the body is considered to be the ultimate proof needed to draw upon a diagnosis, and as such radiology forms a very important role in this
  • The main imaging devices used in diagnostic radiology are: X-Ray; CT; MRI; Ultrasound
  • Further examples of imaging devices often used in diagnostic radiology include: Fluoroscopy; Mammography; PET
  • As mentioned in the 'What is Radiology' page, the general principle of radiology is that radiation is utilised to see what's underneath the skin (more on what radiation is in the 'how it all works' section). As such, the reason there are multiple different types of imaging devices as listed above is because each device has a different way of using radiation to capture images, and often times the differences in how they each emit their radiation is what allows doctors to get the best images of a wide variety of different organs and diseases. Certain pathologies will appear better using certain imaging devices as opposed to others.

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Section 1: Radiology

Section 1: Radiology

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Radiology

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Section 1: Radiology

This first section will teach you about radiology as a general overview. Click the buttons below to explore more about radiology...

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Radiology

Summary

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Governance

Nuclear Medicine

How It All Works

Radiologist Life

Section 1: Radiology

This first section will teach you about radiology as a general overview. Click the buttons below to explore more about radiology...