V/Q Scan

Question 1

two inter alveoli connections that allow for collateral air movement

Answer 1

1. Pores of Kohn
2. Canals of Lambert

Question 2

___ are better ventilated than the ____.

Answer 2

bases of the lungs are better than the apices

Question 3

blood flow is gravity dependent.
when someone is standing or sitting, there is ___ more perfusion at the bases than apices.

Answer 3

3-5x

Question 4

indications for V/Q scans

Answer 4

• PE?
• assessing anticoagulant tx
• covid reso

Question 5

patient prep

Answer 5

• CXR within 24hrs
• rehearsing the breathing procedure

Question 6

contraindications for V/Q

Answer 6

• severe pulmonary HTN

Question 7

when do we reduce particle numbers?

Answer 7

• pts with pneumonectomy or lobectomy
• peds
• R-L cardiac shunts
• pulmonary HTN
• pregnancy

Question 8

RP - ventilation aerosol

Answer 8

133Xe

Question 9

RP - ventilation gas

Answer 9

DTPA, MDP, SC

Question 10

dose of RP aerosol injected into nebulizer

Answer 10

900-1300 MBq

Question 11

ideal aerosol size

Answer 11

0.1 - 0.5 um

Question 12

patient receives approximately ___% of the dose added to the nebulizer

Answer 12

2-5%

Question 13

ventilation technegas RP

Answer 13

pert

Question 14

dose of pert for the technegas machine

Answer 14

400-900 MBq, pt only receives 10%

Question 15

ideal size for the aerosol from technegas

Answer 15

30-60 nm

Question 16

dose and rp for perfusion part of the study

Answer 16

74-222 MBq MAA

Question 17

ideal # of particles

Answer 17

200k-700k with 350k ideal

Question 18

why are ventilation images usually done first?

Answer 18

to check for image quality - positioning, artifacts

Question 19

views for Q scan

Answer 19

ANT/POST, RAO/LPO, LAO/RPO, LATs, SPECT

Question 20

difference with acquiring if using technegas vs. Xe gas or DTPA aerosols

Answer 20

technegas - statics and SPECT
Xe - dynamic views of inspiration, eq., expiration

Question 21

Xe133
inspiration image is done by…

Answer 21

having the pt take a deep breath and holding it for 10 secs

Question 22

Xe133
equilibrium images are done by…

Answer 22

having pt breathe into the machine and obtaining 3, 30 sec images

Question 23

Xe133
how are washout images acquired

Answer 23

turning off the Xe and having the patient breathe normally into the machine

Question 24

how long are patients supposed to breathe the aerosol for?

Answer 24

3-7 mins or 1500-2000 cps

Question 25

which phase of the technegas production actually produces the technegas?

Answer 25

burn phase

Question 26

when injecting the patient for the Q, patients can be sitting or supine. it's up the patient. t/f

Answer 26

false patients must be supine

Question 27

inject the patient for the q scan over _____ respiratory cycles

Answer 27

3-5

Question 28

what ensures a good injection?

Answer 28

3x the count rate of vent

Question 29

if a V/Q scan is needed for a pregnant pt, what should we do?

Answer 29

- reduce the number of particles - do perfusion first, vent, if needed, can be done the next day

Question 30

advantage of vent imaging done with xenon

Answer 30

washout images allow for good sensitivity in detecting ventilation pathologies

Question 31

what is the flow rate of O2 administered through the nebulizer?

Answer 31

8-12LPM

Question 32

ab in same location on both V and Q

Answer 32

matched

Question 33

likely indicator for vent abnormalities

Answer 33

matched

Question 34

Q abnormality, normal vent

Answer 34

mismatched

Question 35

mismatched defects most likely indicate...

Answer 35

PE

Question 36

normal Q, abnormal vent

Answer 36

reverse mismatch

Question 37

modified PIOPED HIGH (>85% PPV)

Answer 37

2 or more large mismatched segmental defects with normal CXR large = >75% of segment

Question 38

what will happen if you pull blood back into the MAA syringe?

Answer 38

it'll cause hot spots on the images

Question 39

quantum mottle

Answer 39

less than 60k particles injected

Question 40

indication for quantitative lung scan

Answer 40

- eval relative lung perfusion preoperatively

Question 41

what are the best views for a quant lung scan?

Answer 41

ANT/POST

Question 42

normal % uptake for right lung? left lung?

Answer 42

right lung = 55% left lung = 45%

Question 43

expiratory reserve volume of ____ is high risk for pulmonary insufficiency post op

Answer 43

<800 ml