URODYNAMICS

RADIONUCLIDE ASSESSMENT OF BLADDER-EMPTYING FUNCTION IN NORMAL MALE POPULATION AND IN PATIENTS BEFORE AND AFTER PROSTATECTOMY DAVID GROSHAR, M.D. OSCAR M. EMBON, M.D. EDWARD S. KORITNY, M.D.

ALEXANDER SAZBON, M.D. ALEX FRENKEL, D.Sc.

From the Division of Nuclear Medicine and Urology, Rebecca Sieff Government Hospital, Safed, and Department of Nuclear Medicine, Rambam Medical Center, Haifa, Israel

!~STRAC T--Radionuclide assessment of the bladder-emptying function was evaluated in 82 nori,~iiindividuals and in 16 patients before and after prostatectomy. The parameters evaluated were: v~age flow rate (AFR), peak flow rate (PFR), corrected peak flow rate (CPFB = eFR/[bladder i;~(t~e] O.5), eiection fraction (EF) of the bladder, and post-voiding residual urine (R U) volume. A o~!~terobserver reproducibility was found in 19 measurements. Urinary flow rates, EF, and B U ~.~ed a h~ghly s,gnificant statzstwal difference between normal mdzwduals and patients before !~:~y: AFR, 9.2 +_ 5.1 vs. 2 . 9 + 1.5 mL/sec; PFR, 19.5 +_ 9.2 vs 7.4 +_ 3.2 mL/sec; CPFR,1.17 !;~')34 vs 0.54 +_ 0.22; El;, 95.6 +_ 4.6 vs 68.2 +_ 23.2 percent; and RU, 11.8 + 15.8vs 93.4 + l~i~nL; respectively. After prostatectomy the urinary flow rates showed a highly significant im~bment and did not differ from the normal individuals: AFR, 7.9 + 2.7 mL/sec; PFR, 19.0 + :.~L/sec; and CPFR, 1.32 + 0.57. The EF after surgery (91.7 + 10.9%) was lower than in ~ a l individuals, but showed a significant improvement compared with EF before surgery. The i~iCfter surgery (27.4 +_ 48.0 mL) although lower than before surgery did not differ significantly n ~ a s greater than in the normal individuals. No relationship between age and flow was found in ~iS~studu Both average and veak flow rates were related to the bladder volume. This method !~bives a single, noninvasive procedure which enables determination of bladder-emptying funcIO!Z,

hniques have been used to auction in the preoperative ients with prostatism, 1 but its lion of the bladder emptying, attention. ~-4 In a previous re~hown that the radionuclide ]der emptying is useful in the ]er outlet obstruction. In our I~ent study, we report the results of the !~i~th0din normal subjects and in patients with ~y enlargement before and after prosta-

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APRIL 1991

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VOLUME XXXVII, NUMBER4

Material and Methods Normal population sample consisted of 82 male patients with a mean age of thirty-nine years (range 18 to 78 yrs) referred for renal scintigraphy, who showed no evidence of voiding disorders after responding to a thorough questionnaire. Such subjective assessment cannot exclude the presence of bladder outlet obstruction especially in the older patients, but in the absence of a more suitable alternative, we relied on this method for normal selection.5 Sixteen 353

male patients with prostatism and m e a n age of sixty-seven (range 57 to 78) were studied before and at one to three months after prostateetomy. They had no previous urologic operation and were referred for surgery for bladder outlet obstruction due to prostatic enlargement.

The ejection fraction (EY' -'- "of the bladder emptying, using the following formul.

Radionuclide study

where m a x i m u m counts w, ber of counts before void counts as the n u m b e r of ec The post-voiding residm bladder was calculated usil mula, it showed a good co with the RU measured b y

The m e t h o d has been previously published, and it is presented here briefly. 4 Renal scintigraphy was performed after intravenous injection of 4 m C i of 99mtechnetium diethylenetriaminepentaacetic acid. At the end of the renal study, twenty-five minutes after the injection, the patient was asked to drink and return with desire to void. The bladder-emptying study was carried out with the patient standing against the detector of a digital g a m m a camera* imaging the bladder in the posterior view. The patient voided into a container, and the volume was measured. C o m p u t e r images of 1 frame/2 seconds were recorded during voiding. A background subtracted time activity curve of the bladder was generated, and the following parameters were determined: Urinary flow rates. (1) Average flow rate ( A F R ) - - d e t e r m i n e d by t h e v o l u m e v o i d e d divided by the voiding time (mL/sec). The time in seconds between the last point of m a x i m u m counts and the first point of m i n i m u m counts was defined as the voiding time. (2) P e a k f l o w r a t e ( P F R ) - - i n o r d e r to measure the PFR, the m e a n (MBER) and peak (PBER) b l a d d e r - e m p t y i n g rates (eounts/sec) were calculated. The MBER is the m e a n value of the derivative time activity curve (mean of all slopes), and the PBER is the m a x i m u m slope value (maximum value of the derivative curve). The average flow rate is proportional to the MBER as the peak flow rate is proportional to the PBER. Then, using the following equation the peak flow rate was determined: PFR = AFR x PBER mL/sec MBER (3) Corrected peak flow rate (CPFR): CPFR = PFR/(bladder volume) 0.5 where bladder volume = volume voided plus residual urine. This is a volume-independent estimate of PFR based on the assumption that PFR is a linear function of the square root of bladder volume. 6 *Apex 415, Elseint Inc., Israel.

354

EF(%) = Max. counts Maximum

RU=

Vol. voided x Max. counts - i

Reproducibility and statisti The measurements were formed by two investigatoI studies (10 normal subject gery) in order to obtain the ducibility. Standard statisti, gression analysis, correlat and standard error of the e used and significance of th~ using the F-ratio test. Pair~ assess the statistical signifie~ ments before and after sur~ test for unpaired values the statistical significance tween the m e a n of the va] tients before and after pros real individuals. M1 the va by the m e a n + SD. Results

Normal population The AFR was 9.2 + 5 19.5 + 9.2 mL/see, and The E F was 95.6 + 4 . 6 p e r 15.8 m L , and the volume The AFR and PFR showed u m e void (r = 0.81, y = 156; and r = 0.76, y = q 111, P < 0.01, respectively No relationship to age was a n d P F R (r = 0.13, y = 1.6; a n d r = 0.08, y = 0.0 a n d r = 0.08, y = 0.05x + N.S., respectively, for AFI~

Prostatectomy patients The urinary flow rate significantly lower before was 2.9 + 1.5 mL/see vs.

UROLOGY

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APRIL 1991

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! mL/sec vs. 19.0 _+ 6.4 m L / 0.54 _+ 0.22vs. 1.32 +_ 0.57 trgery, respectively). T h e E F percent before and 91.7 _+ surgery, w h i c h was signifiae RU showed no significant (93.4 + 115 mL) and after surgery. T h e v o l u m e voided reduced before surgery (129

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+ 54 vs. 220 + 117 mL). Before surgery u r i n a r y flow rates, EF, and RU showed significant statistical difference from the n o r m a l individuals. After surgery, the v o l u m e void and the u r i n a r y flow rates (AFR, PFR, and CPFR) did not differ significantly from the n o r m a l individuals (Table I). T h e r e was, however, a moderate statistical significance in the E F and RU measurements.

Radionuclide

qormal a = 82)

--Prostatectomy (n = 1 6 ) - Preop. Postop.

2 _+ 5.1 t.6-29) 5 + 9.2 L2-44) 7 +_ 0.34 53-2.09) 6 + 4.6 7.9-99.0) 8 _+ 15.8 1.0-127) ,3 _+ 197 ',50-750)

2.9 _+ 1.5 (0.7-5.7) 7.4 + 3.2 (2-12) 0.54 _+ 0.22 (0.16-1.0) 68.2 _+ 23.1 (19-97) 93.4 + 115 (3-450) 129 _+ 54 (30-250)

7.9 _+ 2.7 (4.2-16) 19.0 ___ 6.4 (12-32) 1.32 _+ 0.57 (0.48-2.9) 91.7 _+ 10.9 (58-99) 27.4 _+ 48.0 (1-172) 220 + 117 (110-570)

study Normal vs Preop.

P-Value* Normal vs Postop.

Preop. vs Postop.

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) (range).

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1991

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V O L U M E XXXVII, N U M B E R 4

355

TABLE II. Parameters

Interobserver reproducibility values

Regression Line

AFR PFR CPFR EF RU

y y y y y

= = = = =

1.04x 1.05x 1.11x 0.96x 0.79x

+ +

Correlation Coefficient (r)

Standard Error of Estimate

P-~ (.

0.99 0.97 0.98 0.99 0.98

0.61

0:

0.15 0.62 0.06 3.38 9.81

1.78 0.08 2.80 60.90

Reproducibility

rates) that need no catheteriza m e t h o d s have been describe thirty years for m e a s u r e m e n t rates, 14 and it has been long rc flow rates v a r y w i t h bladder fluence of age in the u r i n a r y troversial. 15 No relationship ] flow was found in this study As expected in the n o r m a l here, the AFR and PFR shox w i t h the volume voided wh: bladder volume once the RU (Fig. 1). Because the flow va volume, the use of a correctc has been used. The C P F R c( m e a s u r e m e n t w i t h the initial and prevents o.verestimation (

All p a r a m e t e r s showed a good correlation (AFR: r = 0.99, PFR: r = 0.97, CPFR: r = 0.98, EF: r = 0.99, and RV: r = 0.98) t h a t was statistically significant, showing that the test has a good interobserver reproducibility (Table

H). Comment Although a full u r o d y n a m i c s examination w i t h pressure/flow m e a s u r e m e n t s is useful in patients w i t h symptoms of prostatism, these require catheterization w h i c h is unpleasant and carries risks of infection and urethral t r a u m a . Thus, the objective assessment of these patients are most often obtained by d e t e r m i n i n g the u r i n a r y flow rates (average a n d p e a k flow

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