1. Vesicoureteral reflux (VUR) is caused when there is failure of the ureterovesical valve which is located at the distal end of the ureter as it enters the urinary bladder
1. This failure results in the reflux of urine from the bladder to the kidney
1. There are several degrees of reflux
2. Reflux may only occur in the distal portion of the ureter (considered the most mild form of VUR)
3. Or reflux may be seen all the way up the ureter and into the renal pelvis (considered the most severe form of VUR)
2. Causes of VUR include: congenital, pathological process, infection, or immaturity of the system
1. Passive factors of VUR
1. Oblique entry of the ureter into the bladder



2. Length of the intramural ureter not being long enough
   1. Length is long enough to not cause reflux
   2. The tunneling of the ureter indicates that there is a possibility of reflux
   3. Ureter tunnel is very short and reflux will occur
   4. If you want to know more about reflux go to http://www.mitrhospital.com/category/vesicoureteral-reflux/19
2. Active factors for VUR
1. Muscle contraction
2. Peristalsis
3. Is usually seen in children or infants and as the child grows VUR, may disappear as the length of the ureter increases with age (known as spontaneous cessation)
1. Occurs in approximately 1% of the pediatric population
2. Chronic VUR causes infection and scarring within the kidneys
2. Methods to diagnosis this disease
1. Radiographic voiding cystourethrography (VCUG) [radiology procedure]
1. Gives excellent anatomical detail
2. Outlines the anatomy of the pelvic calyceal (renal pelvis), ureter, and bladder
3. Shows reflux and severity of the disease (note image below that compare the radiographic procedure with the nuclear medicine procedure)
1. Grades I - V
2. The higher the grade the worse the reflux
4. Disadvantage of VCUG
1. High radiation exposure
2. Low temporal resolution prevents the diagnosis of intermittent VUR
2. Radionuclide cystography (RNC)
1. Advantages
1. Low radiation exposure
2. High temporal resolution
3. High sensitivity in detecting VUG
2. Disadvantage is that it is unable to delineate between the bladder and urethra and its resolution cannot show anatomical detail
3. Grading VUR



1. The above images compare the severity of reflux of urine from the urinary bladder, up the urethra, and finally into the renal pelvis
2. These images compare VCUG to RNC
1. Note the detail seen in VCUG
2. While there is lack of detail in the RNC, one is still able to define the severity of disease
3. Remember the greater the amount of reflux, the greater the severity of VUR
4. RNC procedure
1. There are two types of procedures: direct and indirect

https://www.studyblue.com/#flashcard/view/9667245
2. Indirect RNC is nothing more than a renal scan in which the radiopharmaceutical is administered IV
1. Following the administration of ^99mTcDTPA, a renal scan can be taken
2. Ideally imaging should be started when there is no residual activity in the renal pelvis
3. The patient is not allowed to void until activity is no longer seen in the kidneys (obviously this requires complete patient cooperation - consider the possible difficulty if it is a pediatric patient)
4. Dynamic images are then taken while the patient is sitting upright and voiding into a bedpan or urinal
5. If residual activity is noted in the renal pelvis or urethra, then VUG can be diagnosed
6. This is not the preferred method
3. Direct RNC
1. Patient preparation
1. Urethral catheterization is completed with the patient
2. Once catheterization has been established, drain all urine from the patient's bladder
3. Determine the amount of urine the bladder can hold given the following formula
4. Depending on urine volume obtain a 200 to 500 mL bag of saline

5. The above formula calculated the approximate size the child's bladder based on age
6. Prepare a 1 to 2 mCi of Tc99mDTPA and draw into a syringe
7. Place the saline bag on an IV pole and elevate this above the patient
8. Connect the saline bag to the catheter
9. Patient should be in a supine position, on the imaging table with the camera placed underneath the patient with the detector within the area of interest
10. Set the camera up to collect two dynamic images
1. 1 to 2 second per frame for 30 to 60 minutes
2. One is labeled filling the other dynamic is labeled voiding
11. Several static images should also be prepared to take 1 minute images when the bladder is full and after the patient voids
2. Acquisition
1. Filling (dynamic) images
1. With the patient in the supine position administer the saline into the urinary bladder and start the first set of dynamic images
2. As the saline starts into the bladder inject the radiopharmaceutical
2. Static images - When the bladder is full take at least one or more static images
3. Voiding images
1. If the child is old enough sit the patient upright and place the camera behind the patient
2. If it is an infant, the patient should remain in the supine position
3. Release the clamp on the catheter and start the second set of dynamic images and collect the radio-saline/urine into the appropriate receptacle
4. Take a one-minute post void image
3. Remove the catheter
4. Calculation of residual urine volume

1. Measure the amount of voided urine in mL
2. Draw an ROI around the full urinary bladder and label this as A
3. Draw an ROI around the empty urinary bladder (post void) and label this as B
4. From the above formula, place the counts identified from the ROIs drawn and enter the amount of urine volume
5. Formula determines the amount of residual urine remaining the patient/LI>


http://www.cmej.org.za/index.php/cmej/article/view/2792/3141

Case 1

Case 2

Here is a chapter in Pediatric Nuclear Medicine and Molecular Imaging on "Vesicoureteral Reflux and Radionuclide Cystography."