Respiratory System

Question 1

What rate is volume scan CT thorax usually done at

Answer 1

3-5 ml/s

Question 2

Technique for V/Q scan

Answer 2

Re- image - too small

Question 3

What radiopharmaceutical and technique is used for a V/Q scan

Answer 3

Perfusion: 99 m Tc labelled macroaggregated albumin particles (MAA)
100 MBq max (1 m Sv ED) 10-40 microm - occlude < 0.5 % pulmonary capillary bed - small

Ventilation: 81Kr - krypton gas - 6000 MBq max (0.2 mSv ED)

Also:

99 m Tc -Technegas 40 MBq max (0.6 mSv ED)

99 m Tc -DTPA 80 MBq max (0.4 mSv ED)

133 Xe (Xenon) 400 MBq max (0.4 mSv ED)

99 m Tc -Technegas 40 MBq max (0.6 mSv ED)

Question 4

What ROI HU, rate of injection and HU for optimal main pulmonary artery enhancement is needed for CTPA

Answer 4

• ROI 100-120 HU
• Rate of injection - 4 ml/s
• Optimal PE enhancement - 350 HU

Question 5

What radiopharmaceutical is essential in lung cancer imaging

Answer 5

FDG-PET

Question 6

Which technique in MRI of the lung can detect abnormal distribution of gas in airspaces - impt in asthma, COPD, CF (not in clinical practice)

Answer 6

Breathing in hyperpolarized helium 3He