Optical diagnostics in urology: current applications and future prospects

5-aminolaevulinic acid (5-ALA) accumulates in GIST-T1 cells and photodynamic diagnosis using 5-ALA identifies gastrointestinal stromal tumors (GISTs) in xenograft tumor models

Gastrointestinal stromal tumor (GIST) diagnosis using conventional gastrointestinal endoscopy is difficult because such malignancies cannot be distinguished from other types of submucosal tumors. Photodynamic diagnosis (PDD) is based on the preferential uptake of photosensitizers by tumor tissues and its detection by fluorescence emission upon laser excitation. In this study, we investigated whether PDD using 5-aminolevulinic acid (5-ALA), a standard photosensitizer used worldwide, could be used for GIST diagnosis. 5-ALA is metabolized to endogenous fluorescent protoporphyrin IX (PpIX). We examined the accumulation of PpIX in GIST-T1 cells using flow cytometry and immunofluorescent staining. Furthermore, we established GIST-T1 xenograft mouse models and examined PpIX accumulation in the resultant tumors. PpIX accumulated in GIST-T1 cells and was localized mainly to lysosomes. PpIX accumulation was also observed in murine xenograft tumors. Moreover, tumor and normal tissues could be distinctly identified by relative PpIX fluorescence. Thus, our results demonstrated that PDD with 5-ALA has substantial clinical potential for GIST diagnosis.

Optical and x-ray technology synergies enabling diagnostic and therapeutic applications in medicine

X-ray and optical technologies are the two central pillars for human imaging and therapy. The strengths of x-rays are deep tissue penetration, effective cytotoxicity, and the ability to image with robust projection and computed-tomography methods. The major limitations of x-ray use are the lack of molecular specificity and the carcinogenic risk. In comparison, optical interactions with tissue are strongly scatter dominated, leading to limited tissue penetration, making imaging and therapy largely restricted to superficial or endoscopically directed tissues. However, optical photon energies are comparable with molecular energy levels, thereby providing the strength of intrinsic molecular specificity. Additionally, optical technologies are highly advanced and diversified, being ubiquitously used throughout medicine as the single largest technology sector. Both have dominant spatial localization value, achieved with optical surface scanning or x-ray internal visualization, where one often is used with the other. Therapeutic delivery can also be enhanced by their synergy, where radio-optical and optical-radio interactions can inform about dose or amplify the clinical therapeutic value. An emerging trend is the integration of nanoparticles to serve as molecular intermediates or energy transducers for imaging and therapy, requiring careful design for the interaction either by scintillation or Cherenkov light, and the nanoscale design is impacted by the choices of optical interaction mechanism. The enhancement of optical molecular sensing or sensitization of tissue using x-rays as the energy source is an important emerging field combining x-ray tissue penetration in radiation oncology with the molecular specificity and packaging of optical probes or molecular localization. The ways in which x-rays can enable optical procedures, or optics can enable x-ray procedures, provide a range of new opportunities in both diagnostic and therapeutic medicine. Taken together, these two technologies form the basis for the vast majority of diagnostics and therapeutics in use in clinical medicine.

Feasibility of photoacoustic-guided teleoperated hysterectomies

Hysterectomies (i.e., surgical removal of the uterus) are the prevailing solution to treat medical conditions such as uterine cancer, endometriosis, and uterine prolapse. One complication of hysterectomies is accidental injury to the ureters located within millimeters of the uterine arteries that are severed and cauterized to hinder blood flow and enable full uterus removal. This work explores the feasibility of using photoacoustic imaging to visualize the uterine arteries (and potentially the ureter) when this imaging method is uniquely combined with a da Vinci^® surgical robot that enables teleoperated hysterectomies. We developed a specialized light delivery system to surround a da Vinci^® curved scissor tool, and an ultrasound probe was placed externally, representing a transvaginal approach, to receive the acoustic signals. Photoacoustic images were acquired while sweeping the tool across our custom 3-D uterine vessel model covered in ex vivo bovine tissue that was placed between the 3-D model and the fiber, as well as between the ultrasound probe and the 3-D model. Four tool orientations were explored, and the robot kinematics were used to provide tool position and orientation information simultaneously with each photoacoustic image acquisition. The optimal tool orientation produced images with contrast >10  dB and background signal-to-noise ratios (SNRs) >1.7, indicating minimal acoustic clutter from the tool tip. We achieved similar contrast and SNR measurements with four unique wrist orientations explored with the scissor tool in open and closed configurations. Results indicate that photoacoustic imaging is a promising approach to enable visualization of the uterine arteries to guide hysterectomies (and other gynecological surgeries). These results are additionally applicable to other da Vinci^® surgeries and other surgical instruments with similar tip geometry.

Flexible laser endoscope for minimally invasive photodynamic diagnosis (PDD) and therapy (PDT) toward efficient tumor removal

Photodynamic diagnosis (PDD) provides valuable assistance in distinguishing tumor from the normal tissue using fluorescent colors. These colors are affected by the illumination and the photosensitizer, and PDD may be applied during operation. After the diagnosis, photodynamic therapy (PDT) could destroy tiny lesion without removing the tissue, something that considerably reduces the possibility of tumor recurrence. However, the present endoscope technologies cannot realize PDD and PDT using the same endoscope. The use of different endoscopes presents three main disadvantages. First, the intra-operation diagnosis cannot be realized unless endoscopes are the different during operation; use of different endoscopes further burdens of the surgeon and the patients. Second, it is very difficult to find the exact same area via the PDT endoscope, one that is confirmed as tumor or cancer by the PDD endoscope, when different endoscopes are used just as present applied. Third, the laser irradiation field cannot be controlled with present technologies, something that may hurt the surrounding healthy tissue or blood vessels, thus leading to serious complications. To resolve the above-mentioned problems, we propose a new flexible laser endoscope, which integrates PDD and PDT, and provides a controllable laser irradiation field for the surgeon. Experimental results proved that the resolution of both diagnosis and therapy images were five times higher than that of standard laparoscopy, the laser power density was high enough for PDT for a distance of 20 to 50 mm away from the target tumor, and the position accuracy of the presented system was half of the required errors. Moreover, the in-vitro experiments further verified the effectiveness of the laser endoscope system. Therefore, this new flexible laser endoscope is potentially suitable for future in-vivo experiments or clinical applications.

Novel methods for mapping the cavernous nerves during radical prostatectomy

The cavernous nerves, which course along the surface of the prostate gland, are responsible for erectile function. During radical prostatectomy, urologists are challenged in preserving these nerves and their function. Cavernous nerves are microscopic and show variable location in different patients; therefore, postoperative sexual potency rates are widely variable following radical prostatectomy. A variety of technologies, including electrical and optical nerve stimulation, dye-based optical fluorescence and microscopy, spectroscopy, ultrasound and magnetic resonance imaging have all been used to study cavernous nerve anatomy and physiology, and some of these methods are also potential intraoperative methods for identifying and preserving cavernous nerves. However, all of these technologies have inherent limitations, including slow or inconsistent nerve responses, poor image resolution, shallow image depth, slow image acquisition times and/or safety concerns. New and emerging technologies, as well as multimodal approaches combining existing methods, hold promise for improved postoperative sexual outcomes and patient quality of life following radical prostatectomy.

Clinical and investigative applications of Raman spectroscopy in Urology and Andrology

Raman spectroscopy (RS) is an optical technique that allows for real-time interrogation of biologic tissues with chemical specificity. Using a diode laser, incident photons are scattered on the tissue of interest and the spectral wavelength output is a reflection of the tissues’ molecular fingerprint. Naturally, this technology has come into clinical usage to evaluate benign versus malignant tissue. Within the field of Urology, RS has seen tremendous growth as an optical biopsy tool for the real-time evaluation of diseases of the bladder, prostate, kidney, and testis. With such growing fervor for this emerging spectroscopic modality, we present a current summary of clinical studies utilizing RS within Urology and Andrology to highlight its potential applications.

[Optical coherence tomography for differentiation of parathyroid gland tissue]

BACKGROUND

Optical coherence tomography (OCT) is a high-resolution imaging technique that allows the identification of microarchitectural features in real-time.

OBJECTIVE

Can OCT be used to differentiate parathyroid tissue from other cervical tissue entities?

MATERIAL AND METHODS

All investigations were carried out during cervical operations. Initially, ex vivo images were analyzed to define morphological imaging criteria for each tissue entity. These criteria were used to evaluate a first series of ex vivo images. In a second phase the practicability of the technique was investigated in vivo and in the third phase backscattering intensity measurements were analyzed employing linear discriminant analysis (LDA).

RESULTS

In the ex vivo series parathyroid tissue could be differentiated from other tissue entities with a sensitivity and specificity of 84  % and 94  %, respectively. Parathyroid tissue was correctly identified in the in vivo series in only 69.2 %. The analysis of backscattering intensity profiles employing LDA reliably distinguished between the different tissue types.

CONCLUSION

The OCT images displayed typical characteristics for each tissue entity. Due to technical problems in handling the probe the in vivo OCT images were of much poorer quality. Backscattering intensity measurements illustrated that OCT images provide an individual profile for each tissue entity independent of the defined morphological assessment criteria. The results show that OCT is fundamentally suitable for intraoperative differentiation of tissues.

Backscattering intensity measurements in optical coherence tomography as a method to identify parathyroid glands

BACKGROUND AND OBJECTIVE

Previous studies have shown that the use of optical coherence tomography (OCT) permits the differentiation between parathyroid tissue, thyroid tissue, lymph nodes and adipose tissue. We investigated the backscattering intensity profiles of OCT images in order to determine whether significant differences between these tissue types exist.

METHODS

Mean backscattering intensity profiles were obtained from OCT images of parathyroid glands, thyroid tissue, lymph nodes and adipose tissue. The profiles were analyzed employing Fisher's Linear Discriminant Analysis (LDA). The results were cross validated employing improved parameter estimation techniques.

RESULTS

Mean backscattering intensity profiles from 300 OCT images of 34 patients undergoing thyroid or parathyroid surgery were analyzed. The overall rate of correct classifications was 96.15%. The cross validation employing improved parameter estimation techniques yielded results identical to those derived from Fisher's LDA.

CONCLUSION

Besides the individual assessment of OCT images by interpreting morphological criteria, backscattering intensity measurements can reliably distinguish between different tissue entities.

Studying the distribution of deep Raman spectroscopy signals using liquid tissue phantoms with varying optical properties

We studied experimentally the magnitude and origin of Raman signals in a transmission Raman geometry as a function of optical properties of the medium and the location of Raman scatterer within the phantom.

Intraoperative optical coherence tomography imaging to identify parathyroid glands

OBJECTIVE

Optical coherence tomography (OCT) is a non-invasive high-resolution imaging technique that permits characterization of microarchitectural features in real time. Previous ex vivo studies have shown that the technique is capable of distinguishing between parathyroid tissue, thyroid tissue, lymph nodes, and adipose tissue. The purpose of this study was to evaluate the practicality of OCT during open and minimally invasive parathyroid and thyroid surgery.

METHODS

During parathyroid and thyroid surgery, OCT images were generated from parathyroid glands, thyroid tissue, lymph nodes, and adipose tissue. The images were immediately assessed by the operating team using the previously defined criteria. Second, the OCT images were blinded with respect to their origin and analyzed by two investigators. Whenever possible the OCT findings were matched to the corresponding histology.

RESULTS

A total of 227 OCT images from 27 patients undergoing open or minimally invasive thyroid or parathyroid surgery were analyzed. Parathyroid glands were correctly identified in 69.2%, thyroid tissue in 74.5%, lymph nodes in 37.5%, and adipose tissue in 69.2%. 43 OCT images (18.9%) could not be allocated to one of the tissue types (Table 2). Sensitivity and specificity in distinguishing parathyroid tissue from the other entities were 69% (63 true positive, 13 false negative findings, 15 images where an allocation was not possible) and 66%, respectively (71 true negative, 9 false positive, 28 images where an assessment was not possible).

CONCLUSION

OCT is capable of distinguishing between parathyroid, thyroid, and adipose tissue. An accurate differentiation between parathyroid tissue and lymph nodes was not possible. The disappointing results compared to the previous ex vivo study are related to problems handling the endoscopic probe intraoperatively. However, further refinement of this new technology may lead to OCT systems with higher resolution and intraoperative probes that are easier to handle.

Discrimination of bladder cancer cells from normal urothelial cells with high specificity and sensitivity: combined application of atomic force microscopy and modulated Raman spectroscopy

Atomic force microscopy (AFM) and modulated Raman spectroscopy (MRS) were used to discriminate between living normal human urothelial cells (SV-HUC-1) and bladder tumour cells (MGH-U1) with high specificity and sensitivity. MGH-U1 cells were 1.5-fold smaller, 1.7-fold thicker and 1.4-fold rougher than normal SV-HUC-1 cells. The adhesion energy was 2.6-fold higher in the MGH-U1 cells compared to normal SV-HUC-1 cells, which possibly indicates that bladder tumour cells are more deformable than normal cells. The elastic modulus of MGH-U1 cells was 12-fold lower than SV-HUC-1 cells, suggesting a higher elasticity of the bladder cancer cell membranes. The biochemical fingerprints of cancer cells displayed a higher DNA and lipid content, probably due to an increase in the nuclear to cytoplasm ratio. Normal cells were characterized by higher protein contents. AFM studies revealed a decrease in the lateral dimensions and an increase in thickness of cancer cells compared to normal cells; these studies authenticate the observations from MRS. Nanostructural, nanomechanical and biochemical profiles of bladder cells provide qualitative and quantitative markers to differentiate between normal and cancerous cells at the single cellular level. AFM and MRS allow discrimination between adhesion energy, elasticity and Raman spectra of SV-HUC-1 and MGH-U1 cells with high specificity (83, 98 and 95%) and sensitivity (97, 93 and 98%). Such single-cell-level studies could have a pivotal impact on the development of AFM-Raman combined methodologies for cancer profiling and screening with translational significance.

Prostate cancer detection using combined auto-fluorescence and light reflectance spectroscopy: ex vivo study of human prostates

This study was conducted to evaluate the capability of detecting prostate cancer (PCa) using auto-fluorescence lifetime spectroscopy (AFLS) and light reflectance spectroscopy (LRS). AFLS used excitation at 447 nm with four emission wavelengths (532, 562, 632, and 684 nm), where their lifetimes and weights were analyzed using a double exponent model. LRS was measured between 500 and 840 nm and analyzed by a quantitative model to determine hemoglobin concentrations and light scattering. Both AFLS and LRS were taken on n = 724 distinct locations from both prostate capsular (nc = 185) and parenchymal (np = 539) tissues, including PCa tissue, benign peripheral zone tissue and benign prostatic hyperplasia (BPH), of fresh ex vivo radical prostatectomy specimens from 37 patients with high volume, intermediate-to-high-grade PCa (Gleason score, GS ≥7). AFLS and LRS parameters from parenchymal tissues were analyzed for statistical testing and classification. A feature selection algorithm based on multinomial logistic regression was implemented to identify critical parameters in order to classify high-grade PCa tissue. The regression model was in turn used to classify PCa tissue at the individual aggressive level of GS = 7,8,9. Receiver operating characteristic curves were generated and used to determine classification accuracy for each tissue type. We show that our dual-modal technique resulted in accuracies of 87.9%, 90.1%, and 85.1% for PCa classification at GS = 7, 8, 9 within parenchymal tissues, and up to 91.1%, 91.9%, and 94.3% if capsular tissues were included for detection. Possible biochemical and physiological mechanisms causing signal differences in AFLS and LRS between PCa and benign tissues were also discussed.

Developing an Instrument-Independent Algorithm for Raman Spectroscopy: A Case of Cancer Detection

One of the problems in the use of Raman spectroscopy for cancer detection in clinical application is the variety of Raman instruments, producing different spectra for the same sample, due to the nature of the measurement system. This prevents the measured spectra from different systems to be compared against one another without appropriate tools and techniques. Therefore, for each instrument one needs to spend considerable amount of time to prepare a set of reference data based on which the future measurements to be interpreted. For early diagnosis of cancer by Raman spectroscopy, there is a need for an algorithm by which such diagnosis can be made by any type of Raman instrument giving rise to the same findings. In the present study we have investigated the detection of breast cancer in three classes of breast samples (normal, benign and cancer) using three different Raman instruments (Almega, Bruker and R3000) to develop an algorithm that, irrespective of the type of Raman instrument, can be applied to the spectra to extract the features necessary to arrive at the same diagnosis. In doing so, we employed different pre-processing methods to eliminate the instrument-dependent effects on the spectra enabling us to fuse such spectra obtained from different instruments. Then, we classified the data using support vector machine (SVM) and multi-layer perception (MLP) to assess the degree to which the employed methods have been able to detect cancer. The results of the study showed that the range and resolution matching using spline interpolation, and noise and fluorescence elimination using wavelet and SNV normalizations were the most sensitive and accurate procedures for eliminating the instrumental specification-based effects and fusing the data from different instruments.

Is photodynamic diagnosis ready for introduction in urological clinical practice?

The aim of this review is to provide an up-to-date review of the available literature on photodynamic diagnosis (PDD) for nonmuscle-invasive bladder cancer, to present the technique in a comprehensive approach and, finally, to discuss the relevance of PDD in clinical practice in terms of indications, outcomes and its development trend. A literature search was conducted up to July 2012, using MEDLINE and EMBASE via Ovid databases to identify published studies on PDD for nonmuscle-invasive bladder cancer. Only English-language and human-based full manuscripts that reported on case series and studies with >40 participants, concerning clinical evidence of the technique, its efficacy and safety data were included. Evidence showed that PDD significantly improves detection of bladder cancer compared with standard white-light cystoscopy, having proven to be more effective for the diagnosis of carcinoma in situ. This condition seems to facilitate more complete resections, resulting in a lower residual tumor rate, which, in turn consecutively leads to higher recurrence-free survival rates. The literature search demonstrated that for mid- and long-term follow-up, PDD showed acceptable outcomes in terms of tumor detection, as well as lower residual tumor and lower recurrence rates compared with white-light cystoscopy. It has proven to be safe and well tolerated; the major limitations of PDD are its low specificity and elevated costs.

Applications of Raman spectroscopy to the urinary bladder for cancer diagnostics

Biomolecular changes associated with cancer progression can be identified using Raman spectroscopy, allowing for this technique to be utilized as a non-invasive tool for the diagnosis of bladder cancer. Applications of Raman spectroscopy for diagnostics in real-time have consistently produced higher sensitivities and specificities than current clinical methods. This technique can be applied

Innovations in the endoscopic management of bladder cancer: is the era of white light cystoscopy over

Bladder cancer is the most common tumor of the urinary tract, with a worldwide incidence of 8.6 x 100000 in men and 2.6 x 100000 in women (1). The majority of patients (75-85%) present as non-muscle invasive bladder cancer (NMIBC); within this category the most represented stage is Ta (70%), followed by T1 (20%) and, less frequently, carcinoma in situ (CIS) (10%) (2). The diagnosis of NMIBC and, more generally, of bladder cancer, depends on urine cytology and endoscopic examination with histological evaluation of the resected tissue. Clearly, an optimal cystoscopy with accurate transurethral resection (TUR) is of great importance in order to improve the detection rate and to reduce the probability of recurrence and progression. Today the cystoscopy is routinely performed with the white light technique (WLC), the same of about 80 years ago (3). Several studies have demonstrated that an initial TUR with WLC can miss small papillary lesions and, particularly, flat lesions such as CIS. Moreover, recurrence rates of non-muscle invasive bladder cancer (NMIBC) are directly related to the possibility of achieving a complete resection: residual cancer is present in a large percentage of re-TUR, showing a not so good performance of resection with this method. For these reasons new methodologies have been investigated in order to improve the sensitivity and specificity of WLC, such as photodynamic diagnosis (PDD), narrow band imaging (NBI), optical coherence tomography (OCT) and CT virtual cystoscopy. Some of them have been well established and supported by consistent literature while others are still to be viewed as experimental. The purpose of this review is to investigate the state of the art of these new techniques.

Optical coherence tomography: a novel modality for scrotal imaging

BACKGROUND: For patients with nonobstructive azoospermia, sperm retrieval rates remain modest. We describe the use of optical coherence tomography to improve retrieval rates and to decrease tissue destruction. METHODS: Four patients underwent diagnostic testicular biopsy and imaging with the Niris optical coherence tomography device. We performed a descriptive comparison between optical coherence tomographic images and conventional histology. RESULTS: The measured seminiferous tubule diameter differed by 16 mum between comparative imaging from optical coherence tomography and conventional histology using hematoxylin and eosin staining. CONCLUSION: We illustrate the usefulness of optical coherence tomography in the setting of testicular biopsy and the management of nonobstructive azoospermia.

Intraoperative near infrared fluorescence guided identification of the ureters using low dose methylene blue: a first in human experience

PURPOSE

Near infrared fluorescence imaging is a promising technique that offers real-time visual information during surgery. In this study we report the first clinical results to our knowledge of ureteral imaging using near infrared fluorescence after a simple peripheral infusion of methylene blue. Furthermore, we assessed the optimal timing and dose of methylene blue.

MATERIALS AND METHODS

A total of 12 patients who underwent lower abdominal surgery were included in this prospective feasibility study. Near infrared fluorescence imaging was performed using the Mini-FLARE™ imaging system. To determine optimal timing and dose, methylene blue was injected intravenously at doses of 0.25, 0.5 or 1 mg/kg after exposure of the ureters. Imaging was performed for up to 60 minutes after injection.

RESULTS

In all patients both ureters could be clearly visualized within 10 minutes after infusion of methylene blue. The signal lasted at least up to 60 minutes after injection. The mean signal-to-background ratio of the ureter was 2.27 ± 1.22 (4), 2.61 ± 1.88 (4) and 3.58 ± 3.36 (4) for the 0.25, 0.5 and 1 mg/kg groups, respectively. A mixed model analysis was used to compare signal-to-background ratios among dose groups and times, and to assess the relationship between dose and time. A significant difference among time points (p <0.001) was found. However, no difference was observed among dose groups (p = 0.811).

CONCLUSIONS

This study demonstrates the first successful use of near infrared fluorescence using low dose methylene blue for the identification of the ureters during lower abdominal surgery.

Raman microspectroscopy as a diagnostic tool to study single living nasopharyngeal carcinoma cell lines

Raman spectroscopy can provide molecular-level fingerprint information about the biochemical composition and structure of cells and tissues with excellent spatial resolution. In this study, Raman spectroscopy of 3 different nasopharyngeal carcinoma cell lines C666-1, CNE1, and CNE2 and 1 nasopharyngeal normal cell line NP69 acquired on a piece of silica glass slide are presented to investigate the differences among them. The results show the ratio of I1657/I1449 (= 0.7) could provide good distinction between tumor and normal cell lines very easily, which coincides with existing reports about the study of different cell lines and bronchial tissue. In addition, several statistical analytical methods were used to classify these 4 different cell lines and then achieved an exciting result with great sensitivity and specificity of >90%, respectively. The findings of this work further support former work where cells' Raman spectra were acquired on a different substrate. All of these results indicate Raman spectroscopy has the potential to discriminate between normal and tumor cells and have potential use in early diagnosis of nasopharyngeal carcinoma.

Differentiation between normal renal tissue and renal tumours using functional optical coherence tomography: a phase I in vivo human study

OBJECTIVE

To determine the ability of optical coherence tomography (OCT) in differentiating human renal tumours in an in-vivo setting by assessing differences in attenuation coefficient (µ(OCT); mm(-1)) as a quantitative measurement.

METHODS

Consecutive patients undergoing nephrectomy (partial/radical) or cryoablation for an enhancing solid renal tumour were included in our centre between October 2010 and May 2011. In vivo OCT images were obtained from renal tumour and normal parenchyma during surgery. Ex vivo OCT images of internal (subcapsular) tissue were obtained after longitudinal dissection of the extirpated specimen. Attenuation coefficients of the OCT images were determined off-line and compared between normal renal parenchyma and renal tumours (grouped per tissue type and per individual patient); and between OCT images recorded from tissue surface vs internal (subcapsular) tissue.

RESULTS

In vivo OCT was performed in 16 cases (11 renal cell carcinoma, three benign tumours, one non-diagnostic biopsy and one not-accessible tumour). Median attenuation coefficient of normal renal parenchyma was 5.0 mm(-1) vs 8.2 mm(-1) for tumour tissue (P < 0.001) with normal parenchyma differing significantly from malignant tumour (9.2 mm(-1), P < 0.001) and non-significantly from benign tumour (7.0 mm(-1), P = 0.050). The attenuation coefficient of benign tumours did not differ significantly from that of malignant tumours (7.0 vs 9.2 mm(-1), P = 0.139). Using patients as their own control, attenuation coefficients of normal renal parenchyma differed significantly from malignant tumour (P < 0.001) and non-significantly from benign tumour (P = 0.109). Assessed in 10 patients, there was no significant difference between attenuation coefficients of tumour surface and internal tumour (8.5 vs 9.7 mm(-1) respectively, P = 0.260).

CONCLUSIONS

In this first in vivo study on OCT for differentiation of renal tumours in humans the attenuation coefficients (as a quantitative assessment) differed significantly between normal renal parenchyma and malignant tumour. Tumour surface and internal tumour did not differ significantly, suggesting that a superficial OCT attenuation coefficient reliably assesses tissue composition inside the tumour. These results justify further research on OCT for various clinical applications in the diagnosis of renal tumours.

Raman spectroscopy and its urological applications

Purpose:

The Raman spectroscopic technology can be utilized for the detection of changes occurring at the molecular level during the pathological transformation of the tissue. The potential of its use in urology is still in its infancy and increasing utility of this technology will transform noninvasive tissue diagnosis. The Nobel laureate, Sir C.V. Raman is credited for the discovery of the principles of Raman spectroscopy.

Materials and Methods:

Applications of Raman spectroscopy in the bladder, renal, prostate, and other urological disorders were gathered from Medline and abstracts from recent international urological meetings. Current status and future directions of Raman spectroscopy in urology were also reviewed.

Results:

Raman spectroscopic technology is used to interrogate biological tissues. The potential use of this technology in urology has shown encouraging results in the in vitro diagnosis and grading of cancers of the bladder and the prostate. Raman microprobes have been used for the characterization and identification of renal lithiasis. Technology may be available for the urologists to determine the margin status intraoperatively during partial nephrectomy and radical prostatectomy. The future would see the development of optical fiber probes to incorporate them into catheters, endoscopes, and laparoscopes that will enable the urologist to obtain information during the operation.

Conclusion:

Raman spectroscopy is an exciting tool for real-time diagnosis and in vivo evaluation of living tissue. The potential applications of Raman spectroscopy may herald a new future in the management of various malignant, premalignant, and other benign conditions in urology.

Early detection of premalignant lesions and oral cancer

Cancers of the oral cavity account for approximately 3% of malignancies diagnosed annually in the United States. As with other upper aerodigestive tract cancers, 5-year survival rates for oral cavity cancers decrease with delayed diagnosis. Cancers of the oral cavity are thought to progress from premalignant/precancerous lesions, beginning as hyperplastic tissue and developing into invasive squamous cell carcinoma. Despite the general accessibility of the oral cavity during physical examination, many malignancies are not diagnosed until late stages of disease. To prevent malignant transformation of these oral precursor lesions, multiple screening and detection techniques have been developed to address this problem.

Optical and molecular techniques to identify tumor margins within the larynx

Failure to remove tumor cells from the larynx significantly increases the risk of local recurrence following surgical excision. Healthy tissue must be preserved to optimize long-term vocal and swallowing function. It is essential to accurately distinguish between healthy mucosa, dysplasia, and invasive carcinoma. Optical and molecular examining technologies have been developed to improve tumor margin identification in vivo. We aimed to review the efficacy of these technologies. Published articles were identified using MEDLINE, EMBASE, and Cochrane central register of controlled trials (CENTRAL). Randomized clinical trials are required to establish the benefit to patients and cost to the health service of using 5-aminolevulinic acid (ALA)-induced fluorescent imaging, contact endoscopy, and optical coherence tomography (OCT). Furthermore, primary research is required to validate other techniques, such as confocal endomicroscopy and Raman spectroscopy, and to develop their clinical applications in the larynx.

Optical coherence tomography as a non-invasive imaging technique for preinvasive and invasive neoplasia of the uterine cervix

OBJECTIVE

Optical coherence tomography (OCT) is a non-invasive high-resolution imaging technique that permits characterization of microarchitectural features of tissue up to 2 mm in depth in real time. The purpose of this study was to evaluate the feasibility of OCT for the identification of precancerous (cervical intraepithelial neoplasia (CIN)) and cancerous lesions of the uterine cervix.

METHODS

We conducted a prospective study on the use of OCT in women with suspected CIN. OCT images were obtained on colposcopy from non-suspicious and suspicious areas, and were evaluated independently by two investigators and later compared with the corresponding histology. The sensitivity, specificity, negative and positive predictive values and accuracy of the new technique in identifying CIN or carcinoma were calculated.

RESULTS

Of a total of 610 OCT images, 97 from suspicious areas in 60 women were compared with the corresponding histology. Sixty-three of 67 CIN lesions and four invasive carcinomas were diagnosed correctly on evaluation of the OCT images by the first observer. There were 69 true-positive, 11 true-negative, 13 false-positive and four false-negative results, giving a sensitivity of 95% and a specificity of 46%.

CONCLUSION

OCT is a rapid, easy-to-use modality that provides real-time, microarchitectural information of the cervical epithelium. Further refinement of this technology will lead to OCT systems with a significantly higher resolution and may result in better differentiation of cancerous and precancerous lesions.

Fiberoptic imaging for urologic surgery

Laparoscopic and robot-assisted surgery is likely to be improved with the development of real-time, intraoperative imaging for diagnosis, margin determination, and anatomical definition. A significant goal of much of this effort has been focused upon providing better outcomes after radical prostatectomy. The feasibility of fluorescent imaging of labeled cavernosal nerves in the operative field has been demonstrated in vivo in animals. Other applications of the technology and capability will certainly be developed over time. This article reviews and assesses the potential and capabilities of the different imaging modes currently in use or development.

Vibrational spectroscopy: a clinical tool for cancer diagnostics

Vibrational spectroscopy techniques have demonstrated potential to provide non-destructive, rapid, clinically relevant diagnostic information. Early detection is the most important factor in the prevention of cancer. Raman and infrared spectroscopy enable the biochemical signatures from biological tissues to be extracted and analysed. In conjunction with advanced chemometrics such measurements can contribute to the diagnostic assessment of biological material. This paper also illustrates the complementary advantage of using Raman and FTIR spectroscopy technologies together. Clinical requirements are increasingly met by technological developments which show promise to become a clinical reality. This review summarises recent advances in vibrational spectroscopy and their impact on the diagnosis of cancer.

A new generation of optical diagnostics for bladder cancer: technology, diagnostic accuracy, and future applications

CONTEXT

New developments in optical diagnostics have a potential for less invasive and improved detection of bladder cancer.

OBJECTIVE

To provide an overview of the technology and diagnostic yield of recently developed optical diagnostics for bladder cancer and to outline their potential future applications.

EVIDENCE ACQUISITION

A PubMed literature search was performed, and papers on Raman spectroscopy (RS), optical coherence tomography (OCT), photodynamic diagnosis (PDD) and narrow-band imaging (NBI) regarding bladder cancer were reviewed. Technology, clinical evidence, and future applications of the techniques are discussed.

EVIDENCE SYNTHESIS

With RS, the molecular components of tissue can be measured objectively in qualitative and quantitative ways. The first studies demonstrating human in vivo applicability are still awaited. OCT produces high-resolution, cross-sectional images of tissue, comparable with histopathology, and provides information about depth of tumour growth. The first in vivo studies of OCT demonstrated promising diagnostic accuracy. RS and OCT are not suitable for scanning the entire bladder. PDD is a technique using fluorescence to indicate pathologic tissue. Several studies have shown that PDD increases the detection rate of bladder tumours and improves resection, resulting in fewer early recurrences. The relatively low specificity of PDD remains a problem. NBI enhances contrast of mucosal surface and microvascular structures. The NBI technique has clear advantages over PDD, and the two studies published to date have shown promising preliminary results. PDD and NBI do not contribute to histopathologic diagnosis.

CONCLUSIONS

RS and OCT aim at providing a real-time, minimally invasive, objective prediction of histopathologic diagnosis, while PDD and NBI aim at improving visualisation of bladder tumours. For RS, OCT, and NBI, more research has to be conducted before these techniques can be implemented in the management of bladder cancer. All techniques might be of value in specific clinical scenarios.

Optical coherence tomography of cavernous nerves: a step toward real-time intraoperative imaging during nerve-sparing radical prostatectomy

OBJECTIVES

To demonstrate the use of optical coherence tomography (OCT) for imaging of the cavernous nerve (CN) and periprostatic tissues. The rates of nerve preservation and postoperative potency after radical prostatectomy might improve with better identification of the CN using emerging intraoperative imaging modalities. OCT is an imaging modality that allows for real-time, high-resolution, cross-sectional imaging of tissues.

METHODS

Seven male Sprague-Dawley rats underwent surgery using a midline celiotomy to expose the bladder, prostate, and seminal vesicles. The CNs and major pelvic ganglion were identified. Visual identification of the CN was further confirmed by electrical stimulation with simultaneous intracorporeal pressure measurements. OCT images of the CN, major pelvic ganglion, bladder, prostate, and seminal vesicles were acquired and correlated directly with the histologic findings. Once a baseline technique for the scanning and interpretation of the acquired images was established using the rat model, OCT was used to image ex vivo human prostatectomy specimens.

RESULTS

OCT provided unique imaging characteristics, differentiating the CN from the bladder, prostate, seminal vesicles, and periprostatic fat. OCT images of the CN and prostate correlated well with the histologic findings. OCT of ex vivo human prostatectomy specimens revealed findings similar to those with the rat experiments, with, however, less dramatic architecture visualized in part because of the thicker capsule and more dense stroma of human prostates.

CONCLUSIONS

The results of our study have shown that OCT provides real-time, high-resolution imaging of the CN in the rat model with excellent correlation to the histologic findings. This study provides a basis for the intraoperative use of this emerging technology during nerve-sparing prostatectomy.

Molecular contrast of EGFR expression using gold nanoparticles as a reflectance-based imaging probe

Advanced reflectance-based optical techniques for in vivo imaging often suffer from low contrast between neoplastic and normal tissue and are unable to image early biomolecular changes associated with carcinogenesis, thus limiting their clinical value. In this study, we exploit the resonance light scattering property of gold nanoparticles at their surface plasmon resonance to develop them as potential molecular contrast probes for imaging biomolecular changes during carcinogenesis under reflectance-mode imaging techniques. Gold nanoparticles were synthesized and conjugated to anti-epidermal growth factor receptor (EGFR). Their localization on the EGFR of nasopharyngeal carcinoma CNE2 cells and normal human lung fibroblast (NHLF) cells were imaged and compared under confocal microscopy in vitro. We have shown that the localization of gold bioconjugates on EGFR increases the reflectance properties of CNE2 cells and the regions of increased reflectance correspond to regions of high EGFR expression in the cells. The optical properties of normal fibroblast cells are not greatly affected. These gold bioconjugates are thus able to map the expression of relevant biomarkers and elicit an optical contrast for cancer cells over normal cells under confocal reflectance microscopy. Our study demonstrates the potential of gold nanoparticles to target and probe cancer cells and illuminates them for cancer detection under reflectance-based imaging systems based on biomolecular changes.

Optical adjuncts for enhanced colonoscopic diagnosis

Background

Optical techniques using previously unexploited properties of light interaction with tissue may be valuable in the detection, diagnosis and staging of colorectal neoplasia.

Methods

A Medline search (1990 to present) was conducted on optical diagnostics in the detection of colorectal neoplasia. The reference list of each identified article was reviewed for further relevant papers.

Results and conclusion

Chromoendoscopy is the only optical adjunct to colonoscopy that has been tested in large randomized clinical trials. It improves the detection of small and flat colorectal adenomas, and of neoplasia in chronic ulcerative colitis and hereditary non-polyposis colorectal cancer. All other techniques are the subject of ongoing research and the practicality of population screening with any of the methods has yet to be established. Optical techniques may, however, permit immediate clinical diagnosis, removing the need for histological analysis. They may also improve the diagnosis of early colonic neoplasia.

Imaging the cavernous nerves in the rat prostate using optical coherence tomography

INTRODUCTION

Improvements in identification, imaging, and visualization of the cavernous nerves (CNs) during radical prostatectomy, which are responsible for erectile function, may improve nerve preservation and post-operative potency. Optical coherence tomography (OCT) is capable of real-time, high-resolution, cross-sectional, in vivo tissue imaging. The rat prostate serves as an excellent model for studying the use of OCT for imaging the CNs, as the rat CN is a large, visible, and distinct bundle allowing for easy identification with OCT in addition to histologic confirmation.

MATERIALS AND METHODS

Imaging was performed with the Niris OCT system and a handheld 8 Fr probe, capable of acquiring real-time images with 11-microm axial and 25-microm lateral resolution in tissue. Open surgical exposure of the prostate was performed on a total of six male rats, and OCT images of the prostate, CN, pelvic plexus ganglion, seminal vesicle, blood vessels, and periprostatic fat were acquired. CN electrical stimulation with simultaneous intracorporeal pressure measurements was performed to confirm proper identification of the CNs. The prostate and CNs were also processed for histologic analysis and further confirmation.

RESULTS

Cross-sectional and longitudinal OCT images of the CNs were acquired and compared with histologic sections. The CN and ganglion could be differentiated from the surrounding prostate gland, seminal vesicle, blood vessels, bladder, and fatty tissue.

CONCLUSIONS

We report preliminary results of OCT images of the rat CNs with histologic correlation and erectile stimulation measurements, thus providing interpretation of prostate structures as they appear in OCT images.

Assessment of fiberoptic near-infrared raman spectroscopy for diagnosis of bladder and prostate cancer

OBJECTIVES

To determine whether a fiberoptic Raman system, suitable for in vivo use, is able to differentiate between benign and malignant bladder and prostate pathologic findings in vitro. Raman spectroscopy is an optical technique that provides a measure of the molecular composition of tissue by analyzing the way that tissue scatters laser light. Laboratory studies have shown that the technique can be used to identify and characterize transitional cell carcinoma and prostate adenocarcinoma in vitro.

METHODS

A total of 220 Raman spectra were recorded from 29 snap-frozen bladder samples collected at cystoscopic procedures, and 197 Raman spectra were recorded from 38 snap-frozen prostate samples collected at transurethral resection of the prostate. The spectra were correlated with the histologic features and used to construct separate diagnostic algorithms for the bladder and prostate. These algorithms were tested as to their ability to determine the pathologic finding of a sample from its Raman spectrum.

RESULTS

The bladder algorithm was able to differentiate benign samples (normal and cystitis) from malignant samples (transitional cell carcinoma), with an overall accuracy of 84%. The prostate algorithm was able to differentiate benign samples (benign prostatic hyperplasia and prostatitis) from malignant samples (prostate cancer), with an overall accuracy of 86%.

CONCLUSIONS

The results of this study have demonstrated that the clinical Raman system can provide an accurate and objective method to diagnose prostate and bladder cancer in vitro. Because the Raman probe is suitable for use during endoscopic, laparoscopic, or open procedures, this work paves the way for in vivo studies.

The use of Raman spectroscopy to differentiate between different prostatic adenocarcinoma cell lines

Raman spectroscopy (RS) is an optical technique that provides an objective method of pathological diagnosis based on the molecular composition of tissue. Studies have shown that the technique can accurately identify and grade prostatic adenocarcinoma (CaP) in vitro. This study aimed to determine whether RS was able to differentiate between CaP cell lines of varying degrees of biological aggressiveness. Raman spectra were measured from two well-differentiated, androgen-sensitive cell lines (LNCaP and PCa 2b) and two poorly differentiated, androgen-insensitive cell lines (DU145 and PC 3). Principal component analysis was used to study the molecular differences that exist between cell lines and, in conjunction with linear discriminant analysis, was applied to 200 spectra to construct a diagnostic algorithm capable of differentiating between the different cell lines. The algorithm was able to identify the cell line of each individual cell with an overall sensitivity of 98% and a specificity of 99%. The results further demonstrate the ability of RS to differentiate between CaP samples of varying biological aggressiveness. RS shows promise for application in the diagnosis and grading of CaP in clinical practise as well as providing molecular information on CaP samples in a research setting.

The use of Raman spectroscopy to identify and characterize transitional cell carcinoma in vitro

OBJECTIVE

To determine whether Raman spectroscopy can be used to differentiate between normal, inflammatory and malignant bladder pathologies in vitro, and secondly if it can used to grade and stage transitional cell carcinoma (TCC).

MATERIALS AND METHODS

In all, 1525 Raman spectra were measured from 75 bladder samples comprising normal bladder, cystitis, carcinoma in situ (CIS), TCC and adenocarcinoma. Multivariate analysis was applied to the spectral dataset to construct diagnostic algorithms; these were then tested for their ability to determine the histological diagnosis of each sample from its Raman spectrum.

RESULTS

The diagnostic algorithms could be used to accurately differentiate among the pathological groups, in particular, a three-group algorithm differentiated among normal bladder, cystitis and TCC/CIS with sensitivities and specificities of > 90%. Algorithms could also accurately characterize TCC in terms of splitting them into low (G1/G2) or high (G3) grade and superficial (pTa) or invasive (pT1/pT2) stage.

CONCLUSION

Raman spectroscopy can be used to accurately identify and grade/stage TCC in vitro. The technique therefore shows promise for use as an objective method to assist the pathologist in assessing bladder pathologies. Raman spectroscopy also has potential to provide immediate pathological diagnoses during surgical procedures. Following the promising results of this in vitro study, in vivo cystoscopic studies are planned.