Nuclear Studies Flashcards
What radio-isotope is most commonly used in bone scintigraphy?
Technetium-99m-methylene diphosphonate
- given IV, then use gamma camera 3-4 hours later
Bone scan lesions: compare prostate cancer mets vs renal cancer mets.
Prostate cancer mets are Osteoblastic (hot spot, brighter)
Renal cancer mets are Osteolytic
If a patient has renal obstruction, what study should you perform instead?
CT urogram (duh) or MAG3 renal scan
You do a bone scan and see diffuse skeletal absorption of Technetium-99 without uptake into the kidneys/bladder. What is the etiology?
aka “Super Scan”
May be seen with diffuse metastatic, advanced prostate cancer.
What test is used to measure bone mineral density in patients on androgen deprivation therapy?
Dual Energy Xray Absorptiometry (DEXA)
What are the 3 most commonly used chemicals in radionuclide renal scans?
DMSA (DiMercaptoSuccinic Acid)
MAG3 (MercaptoAcetytriGlycine)
DTPA (DiethyleneTriaminePentaacetic Acid)
Why would you use DMSA renal scan?
Used to identify renal scarring or confirm renal pseudotumors.
DMSA binds to the proximal tubules, thereby highlighting the renal cortex.
- increased density = pseudotumor
- decreased density = cyst or solid tumor
Why would you use a MAG3 scan?
To determine renal function and identify obstruction
Where in the cortex does MAG3 pass to get into the collecting system?
Actively excreted through the renal proximal tubules
What can be used concomitantly to help reduce false positives during a MAG3 scan?
Lasix washout and Foley catheter
What is normal MAG3 half-life time?
< 10 minutes
What is an equivocal MAG3 half-life time?
10-20 minutes
At what half-life time of a MAG3 scan are you concerned about obstruction?
> 20 minutes
What are the two most common causes of a MAG3 scan false positive of obstruction?
Severe renal pelvis dilation, renal insufficiency
When do you use a DTPA renal scan?
To determine GFR and renal function, identify obstruction
