Intravesical ultrasonography for tumor staging in an orthotopically implanted rat model of bladder cancer.
OBJECTIVE
Noninvasive and serial evaluation of tumor development and growth is important in an orthotopic animal bladder tumor model. However, to our knowledge a reliable method has not been established. We determined the usefulness of intravesical ultrasonography for tumor staging and volumetric assessment in an animal model.


METHODS
Tumors with various stages were formed in 20 female Fischer F344 rats by implanting AY-27 rat bladder carcinoma cells. Cells were implanted by instilling a suspension (4x10 cells) into the bladder cavity after urothelial denudation using hydrochloric acid or by directly injecting the cell suspension into the bladder wall. Tumor volume and invasion depth were measured by intravesical ultrasonography using an ultrathin 2.5Fr intraluminal ultrasound catheter via the urethra 7 to 10 days after cancer cell implantation. The rats were then sacrificed for histopathological examination.


RESULTS
All rats showed bladder tumors 7 to 10 days after cancer cell implantation, of which stages varied from superficial to advanced disease. Intravesical ultrasonography showed a clear cross-sectional view of all layers of the bladder wall and enabled visualization of bladder tumors (minimal 0.5 mm in diameter). This approach also provided an accurate diagnosis of tumor invasion into muscle layers and perivesical tissues with precise invasion depth and tumor size. The positive predictive ratio regarding tumor staging reached 85%. Repeat examinations were feasible without noticeable adverse effects.


CONCLUSIONS
Intravesical ultrasonography is a reliable and appropriate noninvasive method for evaluating tumor stage and size in an orthotopic rat bladder tumor model.
Satoh
Hiroyuki
H
Department of Urology, School of Medicine, Faculty of Science and Technology, Keio University, Tokyo, Japan. yau@chp-kiyose-tokyo.jp
Morimoto
Yuji
Y
Arai
Tsunenori
T
Asanuma
Hiroshi
H
Kawauchi
Satoko
S
Seguchi
Kenji
K
Kikuchi
Makoto
M
Murai
Masaru
M
D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000000981:diagnostic imaging* / Q000473:pathology*; D003558:Cystoscopy; D004195:Disease Models, Animal; D019160:Endosonography; D005260:Female; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging / Q000379:methods*; D011237:Predictive Value of Tests; D051381:Rats; D011916:Rats, Inbred F344; D047368:Tumor Burden; D001749:Urinary Bladder Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*