DEVELOPMENT OF TRANSURETHRAL ULTRASONOGRAPHY AND CLINICAL APPLICATION TO THE BLADDER

Abstract

Transurethral ultrasonography has been developed mainly for bladder cancer staging. This sonogram is much better than that obtained by the conventional transrectal scanning or scanning via abdominal wall: for instance, ureteral penetration into the wall was more exactly observed (Fig. 12). Since the bladder is scanned by a probe inside the bladder, this new method is called transurethral intravesical scanning or endoscopic ultrasonography. Our scanning device is suitable for practical use, because it has following advantages 1. High-speed scanning enables a real-time observation of the tomogram. 2. The size of the probe sheath is reduced to 24 F. 3. The scanner can be held by hand. 4. Picture quality was improved by using a 7.5MHz transducer. 5. The vesical area in the dead angle of the scanner is minimized by a probe with head angulating device (Fig. 3) or a transducer faced to retrograde direction (Fig. 2. B).
The vesical structures such as mucosal edema (Fig. 4-6), superficial and deep muscle layer as well as tumor base were clearly determined on the tomogram. Therefore, almost the same criteria as in pathological staging is applied in the ultrasonic staging of bladder cancer. The criteria are as follows; (1) Ta or T₁ tumor: the image of the muscle layer is intact at the tumor base (Fig. 15). (2) T₂ tumor: the image of the muscle layer is superficially indented at the tumor base (Fig. 16). (3) T₃ tumor: the image of the muscle layer is deeply indented or disappeared at the tumor base (Fig. 17).
The tumors often had very characteristic shapes on the tomogram, indicating their stages. Eight patterns of these findings were shown as subsidiary diagnostic finding for cancer staging. (a) An image of tumor base on the mucosal edema is a sign of no muscular infiltration (Fig. 29. a, Fig. 19). (b) An image of clear and undeformed bladder surface beneath the tumor is a sign of no muscular infiltration (Fig. 29. b, Fig. 20) (c) Tumor image with a narrow pedicle is a sign of no muscular infiltration (Fig. 29. c, Fig. 21). Tumor stalk is well observed by pushing the tumor from behind. (d) An image of tumor base with (markedly) irregular border is a sign of (deep) muscular infiltration (Fig. 29. d, Fig. 23, 24). (e) A thickening or split image of the muscle layer at the tumor margin is a sign of deep infiltration (Fig. 29. e, Fig. 25). (f) Tumor image under bladder surface with less deformity is a sign of deep infiltration (Fig. 29. f, Fig. 26). (g) Tumors with smoothly indenting tumor base must be staged carefully by the diagnostic criteria previously shown, however, (deeply) indenting tumor image at the intravesically protruding wall is a sign of (deep) muscular infiltration (Fig. 29. g, Fig. 27. B). (h) Image of tumor spread into the pros tate or other perivesical structure is a sign of stage T₄ (Fig. 29. h, Fig. 28).
67 cases of bladder cancer were examined by our transurethral intravesical scanning system. Scanning was effective except for 3 cases which had main tumors at the bladder neck.
Diagnostic criteria for staging were confirmed in 16 of 17 cases. The correlation between the tumor and the wall observed on the tomogram was proved consistent with the crosssection of the pathological specimen. One misdiagnosis was due to lymphatic invasion in the muscle layer. In these 17 cases, exact comparison between the tomogram and the crosssection of the specimen was possible, because tumors were excized with full thickness of the wall and their shapes were not modified by preoperative treatment.
In total of 58 cases, including transurethrally resected cases and others, ultrasonic findings based on both of diagnostic criteria and subsidiary findings for staging were in accord with the pathological stages except 4 cases.
In other 6 cases, pathological specimen could not be obtained.
It is remarkable that this new system clinically displays minute structures of tumor base as we