Objectives: To assess the feasibility and limitations of endoluminal ultrasound (ELUS) for clinical staging of bladder tumors.
Methods: From 1998 to 1999, 32 patients with transitional cell carcinoma of the bladder were evaluated by high-frequency ELUS using miniature ultrasound transducers (20 MHz, 5.1F or 7.2F) before transurethral resection. Clinical staging using ELUS was compared with the results of pathologic staging.
Results: Seventeen (94%) of the 18 patients with superficial tumors on ELUS were confirmed by pathologic examination to have Stage pTa (n = 12) or Stage pT1 (n = 5) disease, and 11 (63%) of the 14 patients with muscle-invasive tumors on ELUS were confirmed by pathologic evaluation to have Stage pT2a (n = 2) or Stage pT2b (n = 9) disease. In all of the misdiagnosed patients, the tumor lacked a well-defined base and was larger than 2 cm in size. It was difficult to distinguish between Stage Ta and Stage T1 tumors because of the limited resolution of ELUS and between Stage T2a and Stage T2b tumors because of its low penetration.
Conclusions: ELUS using a high-frequency (20 MHz), miniature ultrasound transducer is able to distinguish superficial tumors from those with muscle invasion. However, the lack of penetration of the sonographic beam places major limitations on the evaluation of the depth of the invasion in large (greater than 2 cm) tumors with a broad base.