Radiology Flashcards
- This is an abdominal x-ray taken of a 40 year-old lady who has been admitted through ED with a two week history of diarrhoea, weight loss, lethargy and abdominal cramps.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal.
LARGE BOWEL OBSTRUCTION
Differential diagnoses → malignancy, Crohn disease, colitis, gastroenteritis
• Possible abnormalities:
o Small bowel obstruction → valvulae conniventes are more visible → have a “coiled spring” appearance
o Sigmoid volvulus → “coffee bean” appearance
o Pneumoperitoneum → double wall (Rigler) sign → gas outlines both sides of the bowel wall
o IBD:
Thumbprinting → mucosal thickening of the haustra caused by inflammation and oedema → appear like
thumb prints projecting into the lumen
Lead-pipe colon → loss of normal haustra markings secondary to chronic colitis
Toxic megacolon → colonic dilatation without obstruction associated with colitis
APPROACH TO ABDO XRAY
• A → air → where it should and shouldn’t be
o Air should only be seen in the lumen of the bowel
o Free intraperitoneal air is seen better on erect CXR
o Pneumoperitoneum
• B → bowel → position, size, wall thickness
o Normal small bowel → located centrally, usually contains a small volume of air, has folds running across the
diameter of the lumen known as the plicae circulares
o Normal large bowel → located peripherally, usually contains some air or faecal matter, has folds that run
part of the way across known as the haustral folds
o 3-6-9 rule → small bowel < 3 cm, large bowel < 6 cm, caecum < 9 cm
• D → dense structures, calcification, bones
o Examine lowest ribs, vertebral column, pelvic bones, femoral heads and necks
o Calcification in renal tract or gallbladder stones
• O → organs, soft tissues
o Consolidation in lung bases
o Inguinal hernias
o Liver → RUQ, extends to the hemidiaphragm and past the midline
o Spleen → LUQ, extends to the hemidiaphragm
o Psoas muscle → symmetrical triangles either side of the lumbar spine, narrowest near the diaphragm, widest
at the pelvis
o Kidneys → sit on the psoas muscles, often just see the rounded lower pole
o Lung bases → pulmonary vessels in the bases projected over upper abdomen
• X → external objects, artefacts
190.This is an X-ray of a 71 year-old man, previous laparotomy 10 years ago. Now has 24 hours of abdominal cramps, distension and vomiting.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal (ignore the zipper).
ADHESIONS, COLLAPSED BOWEL
• Likely Bowel Obstruction adhesions from laparotomy 10 years ago
o Distension - Differentiate SBO from LBO - Propose Cause likely to be adhesions o Air Fluid Levels o Narrowing + Lack of Gas distal to narrowing shows site of obstruction
- What are the advantages of CT as an investigation?
Rapid acquisition of images
Provides detailed volumetric studies that can be reconstructed in various planes, with various window levels
Non-invasive study (i.e. no pain caused)
Can negate the need for exploratory surgery
Relatively cheap compared to MRI
Relatively accessible compared to MRI
Higher sensitivity and specificity than plain film radiography
Detailed imaging of bone, viscera, soft tissue, and tumours
IV contrast can be used to enhance imaging
192.What are the disadvantages of CT as an investigation?
Uses ionising radiation and therefore risk of iatrogenic cancers
Higher radiation dose than plain film radiography
Complications associated with IV contrast including allergic reactions, acute kidney injury, cannula site trauma and extravasation of contrast
Claustrophobia can occur due to narrow bore size
Patients must lie flat
Relatively more expensive than plain film radiography and USS
Relatively less accessible in rural areas compared to plain film radiography and USS
Patient management can be complicated by incidental findings
- This is a CT of a young person’s head, taken after an assault.
Please look at this image and tell me what the significant features are and whether they are normal or abnormal.
L. EPIDURAL SHIFT W/OUT MIDLINE SHIFT OR COMPRESSION
- Most likely = Extra-dural haematoma
- Typically biconvex (lens shaped)
- Hyperdense
- May present with mid line shift
Approach to CT Head:
1. Orientation
o Patient details
o Scan details – i.e. axial reformat of a non-contrast enhanced head CT
- Grey-white differentiation (assess sulci and gyri)
- Subarachnoid space, ventricles and cisterns
- Blood/ subdural space
- Soft tissues
- Bony review
7. Check areas: • Tentorium • Orbit and globe • Retropharyngeal space • Foramen magnum
Important to comment on: o Midline shift o Masses or haemorrhage o Patency of cisterns and foramen magnum o Any fractures
- This is a CT abdomen of a 19 year-old woman who has presented with a history of “full abdomen, and swelling up” which has happened over several weeks.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal.
LARGE SIMPLE CYST ON THE MESENTERY
- This is a CT of the legs of the front seat passenger of a car involved in a high speed accident.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal.
MIDHSHAFT FRACTURE OF BOTH TIBIA AND DISTAL LEFT FIBULA
- This is a CT of the abdomen of the driver of a car involved in a high speed accident.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal.
SPLEEN RUPTURE- FREE FLUID IN ABDOMEN, PERISPLENIC FLUID AND ACUTE SPLEEN LACERATION
- This is the chest of a motorbike rider involved in a high speed accident.
Please look at this image and tell me what the significant features are, whether they are normal or abnormal.
XRAY= HAEMOTHORAX AND POTENTIAL BROKEN RIBS
- What are the advantages of MRI as an investigation?
Non-ionising radiation (uses magnetic fields and radiofrequency pulses)
Can be used safely in children and pregnant women
Non-invasive (i.e. no pain caused)
Highly detail volumetric study that can be acquired in any plane
Greater detail acquired of soft tissues, neurological tissue, ligaments and cartilage.
Contrast not necessary but can be used to enhance if required (i.e. angiography)
Functional MRI allows visualisation and understanding of the underlying brain networks
- What are the disadvantages of MRI as an investigation?
Long acquisition time
Patient comfort may be an issues due to noisy machine, small bore size and importance of not moving
Relatively more expensive than other imaging modalities
Relatively less available than other imaging modalities
Safety issues with regards to metallic objects, metal implants and foreign bodies (all MRI equipment must be MRI safe)
Sedation required for small children
Complications associated with IV contrast (allergy and acute kidney injury)
Patient management can be complicated by incidental findings
Difficulties in interpretation due to MRI technology being a rapidly evolving field
- What are the advantages of ultrasound as an investigation?
Non-ionising radiation (uses high frequency sound waves and acoustic reflection)
Mostly non-invasive imaging modality (i.e. doesn’t cause pain)
Relatively more accessible than CT and MRI
Relatively cheaper than CT and MRI
There are very few contraindications to USS
Real-time nature is useful for evaluation of physiology and anatomy
Doppler evaluation of organs and vessels allows physiologic data to be acquired
US images may not be as adversely affected by metallic objects
US examination can easily be extended to cover another organ system or evaluate the contralateral side.
Widely used for procedural applications (injections, biopsy, drains, aspirations)
Smaller machines are portable for bedside scanning applications
There are endoscopic applications of ultrasound
- What are the disadvantages of ultrasound as an investigation?
operator dependent
need training in reading results
US in not capable of evaluating tissues with a high acoustic impedance (e.g. bone and air)
High frequency carry a potential risk of thermal heating or mechanical injury to tissue at a microscopic level (most concerning for foetal imaging)
US image quality is more significantly affected by increased body habitus compared to CT and MRI
Field of view can be limited by acoustic windows
Invasive scanning techniques can cause patient discomfort (i.e. PR and PV scanning)
Some scans require patient preparation (i.e. full bladder, patient fasting)
