Innovations in Endoscopic Imaging for Bladder Cancer

Improving bladder cancer imaging using 3-T functional dynamic contrast-enhanced magnetic resonance imaging

OBJECTIVES

The objective of this study was to assess the capability of T2-weighted magnetic resonance imaging (T2W-MRI) and the additional diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) using multitransmit 3 T in the localization of bladder cancer.

MATERIALS AND METHODS

This prospective study was approved by the local institutional review board. Thirty-six patients were included in the study and provided informed consent. Magnetic resonance imaging scans were performed with T2W-MRI and DCE-MRI on a 3-T multitransmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI before DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference criteria standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Scores of κ were calculated to assess interobserver agreement.

RESULTS

The sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8), and 77% (34/44) for observer 1 and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1 and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. Dynamic contrast-enhanced MRI significantly (P<0.01) improved the sensitivity and accuracy for observer 2. For the 23 patients treated with chemotherapy, DCE-MRI also significantly (P<0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Scores of κ were 0.63 for T2W-MRI alone and 0.78 for additional DCE-MRI. Of 7 subcentimeter malignant tumors, 4 (57%) were identified on T2W images and 6 (86%) were identified on DCE maps. Of 11 malignant tumors within the bladder wall thickening, 6 (55%) were found on T2W images and 10 (91%) were found on DCE maps.

CONCLUSIONS

Compared with conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as well as the localization of small malignant tumors and those within bladder wall thickening.

Optical coherence tomography provides images similar to histology and allows the performance of extensive measurements of drug-eluting metal stents in animal ureters

Optical coherence tomography (OCT) images and histology images of metal stents (MSs) inserted in animal ureters were compared, and the reliability of an OCT-based automated method for the performance of quantitative evaluation of ureteral MSs was evaluated. A zotarolimus-eluting metal stent (ZES) and a bare metal stent (BMS) were inserted in each ureter of ten pigs and six rabbits. OCT was performed in unobstructed stented ureters. Histopathologic examination of the stented ureters embedded in glycol-methacrylate took place. Quadrants of OCT images were compared to their respective histologic images by employing two independent observers who delineated different layers in the quadrants of OCT images and correlated them to the respective histologic quadrants. Manual (integrated OCT device software) and automated measurements of the OCT images using an automated strut detection method were compared. The observers highly agreed on the delineation of urothelium from the lamina propria and the lamina propria from the muscle layer of the ureteral wall. The algorithm measurements were similar to the manual measurements, and the algorithm proved to be reliable in the evaluation of ureteral MSs. Significantly higher endothelial hyperplasia of the BMSs in comparison to the ZESs was also quantitatively demonstrated by the strut detection method. OCT proved to be a reliable method for the evaluation of ureteral MSs. OCT provided images of the stented ureteral lumen similar to light microscopy quality. Measurements of the stented ureter are reliably performed by the automated strut detection method.

Multiphoton microscopy in the evaluation of human bladder biopsies

CONTEXT

Multiphoton microscopy (MPM) is a nonlinear imaging approach, providing cellular and subcellular details from fresh (unprocessed) tissue by exciting intrinsic tissue emissions. With miniaturization and substantially decreased cost on the horizon, MPM is an emerging imaging technique with many potential clinical applications.

OBJECTIVES

To assess the imaging ability and diagnostic accuracy of MPM for human bladder biopsies.

DESIGN

Seventy-seven fresh bladder biopsies were imaged by MPM and subsequently submitted for routine surgical pathology diagnosis. Twelve cases were excluded because of extensive cautery artifact that prohibited definitive diagnosis. Comparison was made between MPM imaging and gold standard sections for each specimen stained with hematoxylin-eosin.

RESULTS

In 57 of 65 cases (88%), accurate MPM diagnoses (benign or neoplastic) were given based on the architecture and/or the cytologic grade. The sensitivity and specificity of MPM in our study were 90.4% and 76.9%, respectively. A positive (neoplastic) diagnosis on MPM had a high predictive value (94%), and negative (benign) diagnoses were sustained on histopathology in two-thirds of cases. Architecture (papillary versus flat) was correctly determined in 56 of 65 cases (86%), and cytologic grade (benign/low grade versus high grade) was assigned correctly in 38 of 56 cases (68%).

CONCLUSIONS

The MPM images alone provided sufficient detail to classify most lesions as either benign or neoplastic using the same basic diagnostic criteria as histopathology (architecture and cytologic grade). Future developments in MPM technology may provide urologists and pathologists with additional screening and diagnostic tools for early detection of bladder cancer. Additional applications of such emerging technologies warrant exploration.

Emerging endoscopic and photodynamic techniques for bladder cancer detection and surveillance

This review provides an overview of emerging techniques, namely, photodynamic diagnosis (PDD), narrow band imaging (NBI), Raman spectroscopy, optical coherence tomography, virtual cystoscopy, and endoscopic microscopy for its use in the diagnosis and surveillance of bladder cancer. The technology, clinical evidence and future applications of these approaches are discussed with particular emphasis on PDD and NBI. These approaches show promise to optimise cystoscopy and transurethral resection of bladder tumours.