Vivian - Chapter 4 (Imagery)

Question 1

What are three crucial elements to mention before describing an imagery?

Answer 1

• Type of investigation
• Verify patient’s demographic details
• Investigation’s date

Question 2

What are the elements to include in the description of an MRI or CT scan?

Answer 2

• Imaging modality and plane (e.g. axial, coronal, or sagittal).
• Describe if the scan is with or without contrast (If contrast is given, is there evidence of contrast enhancement?).
• Describe whether the lesion is intra- or extra-axial.
• Be precise about the anatomical location of the lesion.
• Locate the lesion by its lobe, gyrus, sulcus and most importantly its neurological function.
• Proximity to motor cortex or Broca’s area should also
  be emphasized.
• In addition, for deep-seated lesions, mention the adjacent white matter tracts.
• Suggested treatment: surgical vs. non-surgical management; biopsy vs. subtotal vs. total resections; and potential complications of treatment).
• Include descriptions of mass effect, perilesional oedema and hydrocephalus.

MCAL + WTM

Question 3

Example of case description.

Answer 3

This axial MRI scan T1-weighted image without contrast demonstrates a large solitary well-defined heterogeneous/variable intensity mass in the right/left frontal lobe adjacent to ____. There is also associated surrounding oedema and mass effect as evidenced by the sulcal effacement and compression of the ____ ventricle. These features are suggestive of ____, although other differentials include____. (See Table 4.1 for the differential diagnosis of intracranial lesions.)

Question 4

How does a CT scan work?

Answer 4

It utilizes an X-ray beam, which traverses the patient’s head, and a diametrically opposed detector that measures the extent of resorption.

Question 5

What are the terms to describe a CT scan image?

Answer 5

• Hypodense
• Isodense
• Hyperdense

Question 6

How does an MRI work for every modality?

Answer 6

A strong magnet causes protons in the body to align with that field. When a radiofrequency current is applied the protons spin out of equilibrium. When the radiofrequency filed is turned off the time the protons take to realign and the energy they give off depends on their physical properties which can be translated into an image.

• T1 – Spin-lattice relaxation. The time taken for protons to realign themselves with a magnetic field.
• T2 – Spin-to-spin relaxation. The time taken for protons to return to their out-of-phase state.
• Diffusion weighted – Thermally driven translational movement of water. The same principle can be used to produce diffusion tensor imaging (DTI) to outline white matter tracts.
• Functional – T2 relaxation time of perfused brain – oxyHb. A mismatch of O2 supply and utilization in the activated area causes signal change due to blood-oxygenation-level-dependent (BOLD).
• Perfusion – Bolus tracking after rapid contrast injection.

Question 7

What are the terms to describe an MRI image?

Answer 7

• Hypointense (low signal)
• Isointense
• Hyper-intense (high signal)

Question 8

Please describe the anomaly found.

Answer 8

This axial CT scan demonstrates a left cerebellar cystic lesion with an enhancing mural nodule and compression of the fourth ventricle. There is evidence of surrounding oedema. The right temporal horn appears rather enlarged.