Clinical experience of MRI in two dogs with muscle-invasive transitional cell carcinoma of the urinary bladder

Abstract

This study described high-field magnetic resonance imaging (MRI) and computed tomography (CT) characteristics of muscle-invasive bladder transitional cell carcinoma (TCC) in two dogs. Ultrasonography revealed a urinary bladder mass with ambiguous result about invasion to the muscular layer. Contrast-enhanced CT showed that the bladder wall in which the mass was attached was more intensely enhanced than the normal bladder walls, supporting invasion to the muscular layer. The mass revealed an intermediate signal intensity with interruption of the hypointense muscular layer on T2-weighted MRI and showed greater enhancement compared with the normal bladder wall on postcontrast T1-weighted images. T2-weighted MRI, postcontrast T1-weighted MRI and contrast-enhanced dual-phasic CT were useful for evaluating muscle-invasive bladder TCC in dogs.

Fig. 1.

Ultrasonographic images of the urinary bladder in Dog 1 (A) and Dog 2 (B) show an irregular mass with a heterogeneous echo pattern in the urinary bladder. Invasion to the muscular layer is difficult to evaluate by ultrasonography.

Fig. 2.

Transverse CT (A–C) and MRI (D–F) in Dog 1. The urinary bladder mass is irregular and isoattenuating to the muscular layer in noncontrast CT (A). The mass is enhanced more intensely than the remainder of the bladder wall on arterial phase (B, arrow). Although focal contrast-enhanced lesion in the mass is detected, the entire bladder wall shows mild contrast enhancement on the delayed phase (C). On T2W image, the low signal intensity of the muscular layer is interrupted by the tumor (D, arrow). The mass has an intermediate signal intensity, equal to that of muscle on precontrast T1W image (E) and shows greater enhancement than the normal bladder wall on postcontrast T1W image (F, arrow).

Fig. 3.

Transverse CT (A–C) and MRI (D–F) in Dog 2. The urinary bladder mass is irregular and isoattenuating to the muscular layer in noncontrast CT (A). The mass is attached to the ventral bladder wall (B and C) and enhanced more intensely than the remainder of the bladder wall on arterial phase (B, arrows). On T2W image, the low signal intensity of the muscular layer is interrupted by the tumor (D, arrow). The mass has an intermediate signal intensity on precontrast T1W image (E) and shows greater enhancement than the normal bladder wall on postcontrast T1W image (F, arrow).