Direct and Indirect Cystogram

Question 1

indication

Answer 1

assess reflux of urine from bladder to ureters (VUR)

Question 2

direct method requires…

Answer 2

insertion of catheter for instillation of RP

Question 3

what RP is used for the direct method?

Answer 3

99mTc-SC, DTPA or pert

Question 4

what dose is used for the direct method?

Answer 4

18.5-37 MBq injected into a 500 ml NaCl bag

Question 5

how do you do an indirect cystogram?

Answer 5

• injecting MAG3 or DTPA and during a renal scan
• then waiting 2 hrs without pt voiding and obtaining dynamics as patient voids…

Question 6

how do you estimate the filling volume?

Answer 6

bladder vol = (age + 2) x 30 ml

Question 7

filling phase is occurring during… and for how long?

Answer 7

during RP infusion
5-10 sec/frame for about 1-2 mins (until bladder is full)

Question 8

voiding phase parameters

Answer 8

2-10 sec/frame for 2 mins

Question 9

what is normal for the direct method?

Answer 9

no ureters or kidneys during filling or voiding
only bladder ever

Question 10

what is normal for the indirect method?

Answer 10

see kidneys due to residual tracer + bladder
no reflux back into ureters while voiding

Question 11

residual bladder volume

Answer 11

• ROIs drawn over bladder in pre void and post void statics
• volume of urine measured by calibrated container
• indication of instilled volume

Question 12

formula for residual bladder volume

Answer 12

residual bladder volume = (voided vol (ml) * residual bladder ROI cts)/(pre-void bladder ROI cts - residual bladder ROI cts)