Diffusion properties of transurethral intraprostatic injection.
OBJECTIVE
To evaluate the location and extent of diffusion that occurs when liquid is injected transurethrally into the prostate gland, by correlating real-time fluoroscopy and gross pathology, and to quantify the variables that influence intraprostatic diffusion during chemoablation of the prostate.


METHODS
A solution of diatrizoate meglumine (Hypaque, Nycomed, Princeton, NJ) gentamicin and methylene-blue dye (HGM) was injected transurethrally into the prostate in six dogs, using a passive-deflection needle injection system. The intraprostatic diffusion characteristics were evaluated during each injection using real-time C-arm fluoroscopy, and following each injection by gross examination of methylene blue staining within the prostatic tissues. HGM back-flow into the urethra at the time of injection was assessed by measuring gentamicin levels in the collected bladder irrigant after each injection, using a standard dilution formula.


RESULTS
There was variability in the intraprostatic diffusion both fluoroscopically and grossly. The needle occasionally assumed a straighter trajectory than its intended curve. Intraprostatic diffusion was detected in 12 of 36 injections (33%). Using standard manipulations of various devices increased the intraprostatic diffusion in these injections to almost 80%. There was less intraprostatic diffusion when the injection resistance was either extremely high or absent. There was no extraprostatic extravasation of HGM beyond the prostatic capsule.


CONCLUSIONS
Current methods of transurethral intraprostatic injection are variable for both the diffusion of HGM solution and in needle deployment. The gross diffusion patterns with the HGM solution were consistent with the diffusion patterns documented in our previous research using absolute ethanol. These and other factors may partly explain the variability of the lesions produced with ethanol injection. Therefore, more research is needed to further elucidate the diffusion characteristics of solutions injected intraprostatically using the transurethral approach.
Plante
Mark K
MK
Department of Surgery, Division of Urology, University of Vermont College of Medicine, VT, USA. mark.plante@uvm.edu
Gross
Andrew L
AL
Folsom
Jeffrey B
JB
Zvara
Peter
P
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003558:Cystoscopy; D003974:Diatrizoate Meglumine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004058:Diffusion; D004285:Dogs; D007267:Injections; D008297:Male; D011467:Prostate / Q000378:metabolism*
D003287:Contrast Media; D003974:Diatrizoate Meglumine