Dynamic real-time microscopy of the urinary tract using confocal laser endomicroscopy

Abstract

Objectives: To develop the diagnostic criteria for benign and neoplastic conditions of the urinary tract using probe-based confocal laser endomicroscopy (pCLE), a new technology for dynamic, in vivo imaging with micron-scale resolution. The suggested diagnostic criteria will formulate a guide for pCLE image interpretation in urology.

Methods: Patients scheduled for transurethral resection of bladder tumor (TURBT) or nephrectomy were recruited. After white-light cystoscopy (WLC), fluorescein was administered as contrast. Different areas of the urinary tract were imaged with pCLE via direct contact between the confocal probe and the area of interest. Confocal images were subsequently compared with standard hematoxylin and eosin analysis.

Results: pCLE images were collected from 66 participants, including 2 patients who underwent nephrectomy. We identified key features associated with different anatomic landmarks of the urinary tract, including the kidney, ureter, bladder, prostate, and urethra. In vivo pCLE of the bladder demonstrated distinct differences between normal mucosa and neoplastic tissue. Using mosaicing, a post hoc image-processing algorithm, individual image frames were juxtaposed to form wide-angle views to better evaluate tissue microarchitecture.

Conclusions: In contrast to standard pathologic analysis of fixed tissue with hematoxylin and eosin, pCLE provides real time microscopy of the urinary tract to enable dynamic interrogation of benign and neoplastic tissues in vivo. The diagnostic criteria developed in this study will facilitate adaptation of pCLE for use in conjunction with WLC to expedite diagnosis of urinary tract pathology, particularly bladder cancer.

Published by Elsevier Inc.

Figures

Figure 1

Confocal image processing with mosaicing algorithm that generates panoramic view of the tissue microarchitecture with improved clarity compared to single image frames (inset). (A) Normal bladder urothelium showing umbrella cell layer: note the characteristic large polygonal-shaped cells. (B) Normal prostate imaged through prostatic urethra with multiple dark prostate glands within the white stroma. Note the mosaics significantly increased the overall field of view by ~5-fold.

Figure 2

Probe-based confocal laser endomicroscopy (pCLE) images of the normal urinary tract. All images of the lower urinary tract were acquired in vivo, whereas upper tract images (kidney cortex and ureter) were acquired ex vivo. Note similarities of the urothelium (intermediate cells) between ureter and bladder. Lamina propria is characterized by capillary network of moving erythrocytes. Muscularis propia and perivesical fat images were obtained from the tumor resection bed.

Figure 3

Characteristic in vivo microscopy features of low and high grade urothelial carcinoma compared with corresponding H&E sections. Low grade urothelial carcinoma: (A, B) Crowding of uniform-appearing cells. (C, D) Fibrovascular stalk with a thickened endothelial layer. (E, F) Cross-sectional mosaic view of the fibrovascular stalk containing erythrocytes in the vascular core. High-grade urothelial carcinoma: (G, H) Pleomorphic and distorted sheet of cells. (I, J) Distorted fibrovascular stalk with variably sized vascular cores.

Figure 4

Images of erythematous flat lesions in the bladder by WLC, pCLE, and corresponding H&E sections. (A and D) Cystoscopic view of erythematous patches in 2 patients with CIS. Cautery mark in A used to coregister pCLE imaging and biopsy site. (B and E) Confocal images showing large pleomorphic cells, loss of cellular cohesiveness, and indistinct cellular borders. (C and F) Characteristic histologic images of CIS, with full-thickness high-grade cellular atypia, increased nuclear/cytoplasmic ratios, nuclear hyperchromasia, nuclear pleomorphism, and cellular discohesion. (G) Erythematous patch on WLC with (H) small monomorphic cells infiltrating the lamina propria and (I) chronic lymphocytic infiltrate on histology. (J) Patient with scar from previous TURBT showing (K) normal appearing intermediate cells with clear cell borders and (L) thickened lamina propria on histology.