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3.6. Comprehensive evaluation of radionuclide uroflowmetry

Radionuclide uroflowmetry (UFM) is used for non-invasive examination of the emptying function of the bladder and the dynamics of micturition flow through the urinary tract. We obtain values ??of maximum and average flow through the lower urinary tract, the size of the residue in the bladder, as well as the presence, location and volume of vesico-ureteral reflux . This examination is performed as an indirect UFM after iv application of a nephrotropic radioindicator, or as a direct UFM after application of a radioindicator by catheter directly into the bladder.

Data storage

For indirect UFM, we apply about 100 MBq of 99m Tc-DTPA or MAG3 1 to 2 hours before the examination . Furthermore, the patient drinks heavily but is not allowed to urinate. In direct UFM, just before the examination, the bladder is filled with a 50-100 MBq 99m Tc catheter in physiological saline until a feeling of pressure. The examination itself is then performed in the same way in both cases.

The camera detector equipped with the respective collimator is rotated so that its axis runs horizontally. We examine sitting on a chair with a built-in drainage funnel (opening into a calibrated cylinder), with the back to the detector. Men or. we examine while standing, facing the detector.

Recommended storage mode:

matrix 64x 64, 16 bit, preset 180 frames after 1 sec.

Adjust the camera so that the bladder is at the bottom of the field of view. Once the patient is ready, we start saving the study and after about 10 sec. we ask the patient to start urinating. After the micturition, we store for another 10-15 seconds. and end the study. Using a calibrated measuring cylinder, we measure the volume of micturition and write this value or insert it into the study comment.

Study evaluation

After calling up the scintigraphic study in the basic menu of the OSTNUCLINE system, we will start a comprehensive program UFM - uroflowmetry .

Visual evaluation of images and ROI marking

The program first displays a series of summation frames during micturition, along with the values of the respective time intervals. Contrasting brightness and color modulation is selected to better highlight any reflux. These slides are offered for preliminary verbal evaluation, either by the default standard text of the normal , e.g.

“After the start of the dynamic study, micturition soon begins, in which the
low-residual bladder is emptied quickly enough.

Vesico-ureteral reflux is not observable on scintigraphic images of the filled bladder and urinary tract .

Radionuclide uroflowmetry shows normal micturition flow and low
bladder residue, does not show
vesico-ureteral reflux.

Signature: MUDr. " ,

or a preselected pathological formulation, or by inserting free text . We can print a series of images, including text, in pathological cases.

Definition of areas of interest:

ROI 1 .......... filled bladder
ROI 2 .......... body background area
optional for reflux assessment:
ROI 3 .......... left ureter and pelvis
ROI 4 .......... right ureter and pelvis

We usually mark ROI 1 in the first image, for the next ROI we gradually step through the images in the study so that the ureters or the background structure are displayed. If we do not want to quantify vesico-ureteral reflux, we will mark only the regions ROI 1 and ROI 2.

Mathematical processing of curves

From the defined ROIs, the program then creates curves of the time course of radioactivity during micturition; followed by their mathematical processing. The background correction is performed and the sections of the filled bladder and the residue (emptied bladder) are automatically defined on the bladder volume curve (with the possibility of manual modification). At the appropriate query, we enter the value of the mict volume measured during the examination with a measuring cylinder. The program relates this value to the difference in pulse frequency between the filled bladder and the residue, thus determining the conversion factor between the number of stored pulses and the volume in milliliters. The bladder curve calibrated by this factor becomes a volume curve expressing the instantaneous bladder volume [ ml. ]during micturition. From the volume curve, determine the initial volume of the filled bladder and the bladder residue in ml.

Differentiating the curves volumové bladder by time ignites ka speed curve voiding every point of which indicates the instantaneous speed of emptying the bladder, i.e. the instantaneous flow during micturition in [ml./sec.] . Three significant points are then automatically defined on the velocity curve: the beginning of the micturition, the end of the micturition, and the point of maximum micturition speed .

The volum and velocity curve are then displayed simultaneously on the screen together with the time axis [ sec. ] and the volume axis [ml./sec.] , and below it the calculated urodynamic parameters are displayed - bladder volume, micturition volume and bladder residuum [ml.], micturition duration, maximum and average micturition speed [ml./sec.] , UFM index :

                                                  Qmax                                                                   Qmean
       Max. UFM-index   =   ------       ,        Mean UFM-index   =   ------         ,
                                                    Ö Vmik                                                               Ö Vmik

where Qmax is the maximum mict flow, Qmean is the average mict flow and V mik is the mict volume. The UFM-index is a quantity that takes into account the maximum and average flow of micturition in relation to the total volume of micturition.

If ROI2 and ROI3 (ie ureters or pelvises) were defined, quantification of vesico-ureteral reflux follows . The curves of the time course of radioactivity in the ureters and pelvis of the kidneys are corrected in the background, smoothed and calibrated, thus creating curves of the immediate urine volume in the ureters and pelvis of the kidneys. These curves are displayed, photographed and evaluated for the presence and severity of vesico-ureteral reflux.

Final protocol

Finally, the most important UFM parameters are displayed together with the verbal evaluation inserted during the evaluation or generated automatically. The micturition flow is commented (normal-reduced) using the value of the UFM-index, which takes into account the micturition flow in relation to the micturition volume. It is possible to modify or supplement the verbal evaluation and write the conclusion and signature of the evaluating doctor. The prepared image, quantitative and verbal data are then printed in the final report - Fig.3.6.1.

For micturition volumes below approx. 100 ml. in adults and below about 70 ml. in the case of children, we note in the verbal evaluation that the calculated values ??are unreliable due to the small volume of micturition.

UFM program structure

The comprehensive UFM program consists of the following parts (capable of various functions):

UFM 1 - display of a series of images, verbal evaluation, ROI marking
UFM 2 - curve processing, urodynamic quantification, report printing

At the same time, this structure shows how to proceed after interrupting the program or restarting the program in order to repeat a certain part of the calculations.

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