Optical coherence tomography of the upper urinary tract: Review of initial experience ex vivo and in vivo

Contemporary status of diagnostic endoluminal ultrasound and optical coherence tomography in the ureter

Objective

To evaluate via a review of published literature, the efficacy of endoluminal ultrasound (ELUS) and optical coherence tomography (OCT) in the following ureteric diseases: urolithiasis, upper tract urothelial carcinoma, stricture disease and pelvic-ureteric junction obstruction (PUJO).

Patients and methods

Ureteric high-frequency ELUS provides 360° imaging, to a depth of 20 mm, and has been demonstrated to assess ureteric stricture length, degree of fibrosis and aetiology. OCT produces high-quality images with a penetration depth of 2 mm. ELUS has proven to be useful at the time of endopyelotomy for PUJO as it can identify crossing vessels, some not detectable on CT angiography, allowing the urologist to avoid these when making their incision. Ureteric ELUS may be utilised for submucosal ureteric stones as they are highly visible. Endoluminal ultrasound may be deployed in the case of known sub-mucosal urolithiasis when the ureter appears stone-free. It may help identify sub-mucosal stones or stones within diverticulum.

Results

Endoluminal ultrasound has been analysed for its use in determining muscle-invasive urothelial carcinoma of the ureter. The PPV for ≥pT2 was only 16.7% in one study of six patients with MIBC and 76.2% in 21 patients with

Conclusions

Ureteric ELUS has been reported to be a useful tool in endopyelotomy, urolithiasis and stricture disease. The staging of ureteric urothelial carcinoma remains unsatisfactory with current imaging techniques and biopsy methods, and, based on the current literature, ELUS does not appear to have a strong enough PPV to determine muscle invasion. Ureteric OCT may be a useful tool in the future staging of upper tract urothelial carcinoma, particularly in differentiating the stage of small tumours. Further studies are needed in this area.

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Key Words

• endoluminal ultrasound
• optical coherence tomography
• ureter

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Affiliation(s)

Samuel Sii Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
Jeremy Bolton Monash UniversityMelbourneVictoriaAustralia
Jake Tempo Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia
Damien Bolton Department of SurgeryUniversity of Melbourne, Austin HealthMelbourneVictoriaAustralia

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Application of optical coherence tomography in clinical diagnosis

BACKGROUND

Optical coherence tomography (OCT) is a non-invasive diagnosing tool used in clinics. Due to its high resolution (<10um), it is appropriate for the early detection of tiny infections. It has been widely used in diagnosis and treatment of diseases, evaluation of therapeutic efficacy, and monitoring of various physiological and pathological processes.

OBJECTIVE

To systemically review literature to summarize the clinic application of OCT in recent years.

METHODS

For clinic applications that OCT has been applied, we selected studies that describe the most relevant works. The discussion included: 1) which tissue could be used in the OCT detection, 2) which character of different tissue could be used as diagnosing criteria, 3) which diseases and pathological process have been diagnosed or monitored using OCT imaging, and 4) the recent development of clinic OCT diagnosing.

RESULTS

The literature showed that the OCT had been listed as a routine test choice for ophthalmic diseases, while the first commercial product for cardiovascular OCT detection had gotten clearance. Meanwhile, as the development of commercial benchtop OCT equipment and tiny fiber probe, the commercial application of OCT in dermatology, dentistry, gastroenterology and urology also had great potential in the near future.

CONCLUSIONS

The analysis and discussions showed that OCT, as an optical diagnosing method, has been used successfully in many clinical fields, and has the potential to be a standard inspection method in several clinic fields, such as dermatology, dentistry and cardiovascular.

Combined use of fluorescence cystoscopy and cross-polarization OCT for diagnosis of bladder cancer and correlation with immunohistochemical markers

The combined use of fluorescence cystoscopy and cross-polarization optical coherence tomography (CP OCT) with quantitative estimation of the OCT signal was assessed in 92 bladder zones. It demonstrated the diagnostic accuracy in detecting superficial bladder cancer of 93.6%, sensitivity 96.4%, specificity 92.1%, positive predictive value 87% and negative predictive value 97.9%. Quantitative estimation of OCT signal standard deviation in cross-polarization (CP OCT SD index) makes the visual criteria of CP OCT image assessment more objective. The level of CP OCT SD index for diagnosing superficial bladder cancer, including cancer in situ, was 4.32 dB and lower. When tumor is located on a postoperative scar, CP OCT SD index may be higher than the threshold level of 4.32 dB due to strong scattering and depolarization in scar fibrous tissue. A high inverse correlation was found between CP OCT SD index and the level expressed by p63, Ki-67, p53, CD44v6 markers.

Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study

The capabilities of cross-polarization optical coherence tomography (CP OCT) for early bladder-cancer detection are assessed in statistical study and compared with the traditional OCT. Unlike the traditional OCT that demonstrates images only in copolarization, CP OCT acquires images in cross-polarization and copolarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. CP OCT demonstrated sensitivity 93.7% (vs. 81.2%, <0.0001), specificity 84% (vs. 70.0%, <0.001) and accuracy 85.3% (vs. 71.5%, <0.001) in detecting flat malignant bladder lesions, which is significantly better than with the traditional OCT. Higher diagnostic efficacy of CP OCT in detecting early bladder cancer is associated with the ability to detect changes in epithelium and connective tissues.