Raman spectroscopy for optical diagnosis in normal and cancerous tissue of the nasopharynx-preliminary findings

BACKGROUND AND OBJECTIVES: Raman spectroscopy (RS), which can detect molecular changes associated with cancer, was explored as a means of distinguishing normal and cancerous nasopharyngeal tissue. STUDY DESIGN/PATIENTS AND METHODS: Tissue from six patients with normal and cancerous biopsies was studied using a rapid acquisition Raman spectrometer. RESULTS: Spectra were obtainable within 5 seconds. Consistent differences were noted between normal and cancer tissue in three bands 1,290-1,320 cm(-1) (P = 0.005), 1,420-1,470 cm(-1) (P = 0.006), and 1,530-1,580 cm(-1) (P = 0.002). CONCLUSIONS: Spectral differences appear to exist between normal and cancerous nasopharyngeal tissue. The ability to obtain spectra rapidly supports the potential for future in vivo application.     

Multivariate analysis of laryngeal fluorescence spectra recorded in vivo

BACKGROUND AND OBJECTIVE: The potential of using various multivariate analysis methods for classification of fluorescence spectra acquired in vivo from laryngeal tissues in Patients was investigated. STUDY DESIGN/MATERIALS AND METHODS: Autofluorescence spectra were measured on 29 normal tissue sites and 25 laryngeal lesions using 337-nm excitation. Four different multivariate analysis schemes were applied. Laryngeal fluorescence spectra from patients who had been administered delta-aminolevulinic acid (ALA) were obtained using 405-nm excitation and were classified using partial least squares discriminant analysis (PLS-DA). RESULTS: For autofluorescence spectra, logistic regression based on principal component analysis (PCA) or PLS, or PLS-DA all resulted in sensitivities and specificities around 90% for lesion vs. normal. Using ALA and 405-nm excitation gave a sensitivity of 100% and a specificity of 69%. CONCLUSION: Multivariate analysis of fluorescence spectra could allow classification of laryngeal lesions in vivo with high sensitivity and specificity. PLS performs at least as well as PCA, and PLS-DA performs as well as logistic regression techniques on these data.     

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.     

Case series about ex vivo identification of squamous cell carcinomas by laser-induced autofluorescence and Fourier transform infrared spectroscopy

An ex vivo case series aimed at identification of normal laryngeal tissue from laryngeal epidermoid squamous keratinized carcinoma by measuring laser-induced autofluorescence (LIAF) and Fourier transform infrared–attenuated total reflectance (FTIR-ATR) spectra is presented. The case series results were obtained for paired samples extracted from three patients (exclusion: macroscopic changes of normal vocal cord observed during surgery; surgical intervention on vocal cord, treated only with chemotherapy or radiotherapy for carcinoma; inclusion: men, aged 57–68, non-smokers). For LIAF analysis, a 375-nm picosecond pulsed laser diode with 31 MHz pulse repetition rate, 100 ps full-time width at half-maximum, and average power 0.49 μW was used. LIAF and FTIR-ATR spectra show noticeable differences between normal and malignant tissues. LIAF spectra differed in shape of emitted band, peak position, and band relative intensity of the two kinds of samples, evidencing hypsochromic shift and mean fluorescence intensity decrease of (75.42?±?3)% in malignant tissue with respect to the normal one. The lack of 1745 cm^?1 band in FTIR-ATR spectra for malignant tissues could be considered an important indicative of the presence of this kind of tissue; moreover, it resulted a greater contribution of lipids and proteins in normal tissue and of collagen in malignant tissue. Penetration depth of the evanescent wave was about 2 μm at an angle of 42°. The two spectroscopic methods are complementary, are applicable for real-time measurements, and may enhance cancer detection and diagnostics. Results presented in this study evidence the potential of the two methods for future in vivo studies.     

Raman Spectroscopy: A Novel Experimental Approach to Evaluating Renal Tumours

Background

New optical techniques of spectroscopy have shown promising results in the evaluation of solid tumours.

Objective

To evaluate the potential of Raman spectroscopy (RS) to assess renal tumours at surgery.

Design, setting, and participants

Over a 5-mo period, Raman optical spectra were prospectively acquired on surgical renal specimens removed due to suspicion of cancer.

Measurements

Raman measures were normalised to ensure comparison between spectra. A lower resolution signal was computed using a wavelet decomposition procedure to diminish the size of the signal and exploit the complete spectrum. A support vector machine (SVM) with a linear kernel and a sequential minimal optimisation solver was applied. A leave-one-out cross-validation technique was used to train and test the SVM.

Results and limitations

There were 36 patients with 34 malignant tumours (27 clear-cell, 6 papillary, and 1 chromophobe) and 2 benign (1 oncocytoma and 1 metanephric cyst) tumours. A total of 241 analysable Raman spectra were obtained. The SVM was able to classify tumoural and normal tissue with an accuracy of 84% (sensitivity 82%, specificity 87%). High-grade and low-grade tumours were differentiated with a precision of 82% (sensitivity 84%, specificity 80%). Histologic subtype could be categorised with an accuracy of 93% (sensitivity 96%, specificity 87%). SVM could not be applied to classify benign and malignant tumours because of the restricted number of benign spectra.

Conclusions

RS can accurately differentiate normal and tumoural renal tissue, low-grade and high-grade renal tumours, and histologic subtype of renal cell carcinoma. Larger prospective studies are needed to confirm these preliminary data.     

Glucose transporter-1 expression in urothelial papilloma of the bladder

INTRODUCTION: Urothelial papilloma should be distinguished from low-grade urothelial carcinoma. We report our experience with glucose transporter-1 (Glut-1) expression in urothelial papilloma. MATERIALS AND METHODS: From January 1987 to December 2002, 32 patients with papilloma were diagnosed. Glut-1 protein expression was studied in 32 cases of papilloma and 30 cases of carcinoma. Clinical information was obtained by chart review. RESULTS: Mean age was 54.7 years, and the solitary lesion was 78.1%. No case of bladder papilloma expressed Glut-1 protein even in cases of recurrent papilloma. However, 67% of urothelial carcinoma specimens were stained for Glut-1 protein. Two patients developed recurrent papilloma (6.2%), 1 of whom (3.1%) developed an urothelial carcinoma 4 years after diagnosis of papilloma. CONCLUSIONS: The study showed that papilloma does not express the Glut-1 protein in contrast to urothelial carcinoma. This distinctive expression pattern of Glut-1 will possibly contribute to differentiate urothelial papilloma from low-grade urothelial carcinoma.     

Correlation between near-infrared Raman spectroscopy and the histopathological analysis of atherosclerosis in human coronary arteries

BACKGROUND AND OBJECTIVES: Modern diagnostic methods such as near-infrared Raman spectroscopy (NIRS) allow quantification and evaluation of human atherosclerotic lesions, which can be useful in diagnosing coronary artery disease. The objective of the present study is to obtain feasible diagnostic information to detect atheromatous plaque using NIRS combined with discriminant analysis. STUDY DESIGN/MATERIAL AND METHODS: An 830 nm Ti: sapphire laser pumped by an argon laser provides near-infrared excitation. A spectrograph disperses light scattered from arterial tissue and a liquid-nitrogen cooled CCD detects the Raman spectra. A total of 111 arterial fragments were scanned and Raman results were compared with histopathology. Principal components analysis (PCA) and Mahalanobis distance (m-distance) were used to model an algorithm for tissue classification into three categories: non-atherosclerotic (NA), non-calcified (NC), and calcified (C) using Raman spectra. Spectra were randomly separated into training and prospective groups. RESULTS: It has been found that, for the NA tissue, the algorithm has sensitivity of 84 and 78% and specificity of 91 and 93% for training and prospective groups, respectively. For the NC tissue the algorithm has sensitivity of 88 and 90% and specificity of 88 and 83%. For the C tissue both sensitivity and specificity were maximum, 100%. CONCLUSIONS: An algorithm using PCA and discriminant analysis based on m-distance has been developed and successfully applied to diagnose coronary artery disease by NIRS obtaining good sensitivity and specificity for each tissue category.     

The ability of tumor volume to predict local control in surgically treated squamous cell carcinoma of the supraglottic larynx

PURPOSE: Pretreatment CT volumetric measurement of the primary tumor has been shown to be a predictor of local control in patients with laryngeal carcinoma treated with radiation therapy (RT) alone. A direct association has been demonstrated between tumor volume of supraglottic squamous cell carcinoma (SGSCCA) and local control. However, the association between tumor volume of SGSCCA and local control has not been investigated in patients treated surgically. The purpose of this study was to determine the relationship between SGSCCA tumor volume and local control in patients treated surgically. MATERIALS AND METHODS: Primary site tumor volume was calculated from pretreatment CT studies in 37 laryngeal supraglottic carcinomas treated surgically. All patients had clinical follow-up for evidence of recurrent tumor along the surgical margins at the primary site for a minimum of 2 years after completion of treatment. Statistical analysis consisted of Mantel-Haenszel chi-square tests and Fisher's exact test. RESULTS: Overall local control rate was 92% (33 of 37). Tumor volume was significantly associated with local control (p <. 05). Local control rate for tumors with volumes <16 cc was 94% (32 of 34) (p <.05). CONCLUSIONS: Pretreatment CT volumetric analysis is useful for predicting local control in patients with SGSCCA carcinoma treated surgically.     

FT-raman spectra of the border of infiltrating ductal carcinoma lesions

OBJECTIVE: The characterization of the FT-Raman spectra of the borders of lesions is of great importance in guiding the surgeon during surgical intervention. BACKGROUND DATA: The main goals of this study were to investigate spectra of the borders of lesions of samples of infiltrating ductal carcinoma (IDC) and to determine the characteristics of these spectra. METHODS: A total of 93 spectra were collected from five samples of healthy tissues and from 13 samples of IDC breast tissues using FT-Raman spectroscopy. Cluster analysis was used to separate the spectra into different groups. The results obtained from the statistical analysis were confirmed by a histopathological analysis. RESULTS: The results showed that 17 out of the 67 spectra collected from the IDC samples demonstrated wide variety. The only significant difference between the peaks of the spectra of normal tissues and those of lesion borders is a peak at 538 cm(1) . This peak is related to disulfide bridges in cysteine, and it seems to be the main factor for the FT-Raman determination of the boundaries between healthy and pathological tissue. CONCLUSIONS: These results serve as a foundation for future studies and application of Raman spectroscopy for optical diagnosis to guide biopsy and surgical intervention.     

端粒酶活性在人膀胱肿瘤组织中表达的临床意义

目的：探讨不同临床病理类型的膀胱肿瘤及癌旁组织端粒酶活性表达及临床意义，方法：以改良TRAP法测定91例膀胱肿瘤组织标本端粒酶活性表达。结果：83例膀胱移行细胞癌组织中78例检测到端粒酶活性，阳性率为94％，其对应的癌旁组织也有14％的检出率，8例膀胱乳头状瘤组织中4例检测到端粒酶活性，阳性率为50％，其对应的癌旁组织检出率为12％，端粒酶活性在不同临床病理类型的膀胱肿瘤及癌旁组织中表达差异无显著性意义（P＞0．05），结论：膀胱肿瘤及癌旁组织端粒酶活性的检测对肿瘤的诊断有重要意义。     

Near‐infrared Raman spectroscopy for early diagnosis and typing of adenocarcinoma in the stomach

Background:

The aim of this study was to evaluate the feasibility of using near‐infrared (NIR) Raman spectroscopy for early diagnosis and typing of intestinal and diffuse adenocarcinoma of the stomach.

Methods:

A dispersive‐type NIR Raman system was used for tissue measurements. One hundred gastric tissue samples from 62 patients who underwent endoscopy or gastrectomy were used (70 normal tissue specimens and 30 adenocarcinomas). Principal components analysis (PCA) and multinomial logistic regression (MNLR) were used to develop diagnostic algorithms for tissue classification.

Results:

High‐quality Raman spectra ranging from 800 to 1800 cm^?1 were acquired from gastric tissue within 5 s. There were significant differences in Raman spectra between normal stomach and the two gastric adenocarcinoma subtypes, particularly in the spectral ranges 850–1150, 1200–1500 and 1600–1750 cm^?1, which contain signals related to proteins, nucleic acids and lipids. PCA–MNLR achieved predictive accuracies of 88, 92 and 94 per cent for normal stomach, and intestinal‐ and diffuse‐type gastric adenocarcinomas respectively.

Conclusion:

NIR Raman spectroscopy can detect gastric malignancy and identify the subtype of gastric adenocarcinoma. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.     

Comparative assessment of aluminum and lead concentrations in serum and tissue bioptates in patients with laryngeal papilloma or cancer

A comparative assessment of toxic element concentrations in serum and tissue bioptates in patients with laryngeal papilloma or cancer was performed. Examinations were conducted in 60 patients (40 men and 20 women) aged 20-88 years (average 59 +/- 05). Patients were divided into 3 groups; 20 patients with laryngeal papilloma were in group I, 20 with laryngeal cancer were in group II, and 20 with deviated nasal septums were included as a control group (III). Diagnosis of laryngeal papilloma (removed by direct microlaryngoscopy--Kleinsasser method) and laryngeal cancer (removed by the Rethi method) was histopatologically confirmed in patients from groups I and II, respectively. Patients in the control group received functional surgery to repair deviated nasal septums. Serum and tissue samples were obtained from all patients before surgery. Aluminum and lead concentrations were analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES) using a Spectroflame M spectrometer. The considerable rise of aluminum and lead concentration in tissue bioptates and aluminum in serum in groups I and II in comparison to the control group suggests that these elements may play a significant part in the aetiology and development of precancerous lesions and laryngeal cancers. Measuring toxic chemical element concentrations in tissue bioptates can be useful in the diagnosis and estimation of development of precancerous lesions of the larynx as well as laryngeal cancer. Toxic elements concentration may play a significant role in carcinogenesis and may determine trends in cancer aetiology.     

Transoral laser microsurgery for carcinoma of the supraglottic larynx

OBJECTIVES: The study goal was to report the oncologic outcomes of transoral laser microsurgery (TLM) in the treatment of squamous cell carcinoma of the supraglottic larynx. STUDY DESIGN AND SETTING: A two-center prospective case series analysis. RESULTS: Thirty-eight patients underwent TLM for previously untreated carcinoma of the supraglottic larynx between 1997 and 2005. Pathological T stages were T1 in 8 (21%), T2 in 14 (37%), T3 in 8 (21%), and T4 in 8 (21%). Twenty-six patients (68%) had neck dissections. Thirteen patients (34%) received adjuvant radiotherapy. The mean follow-up for all patients was 31 months. The 2-year Kaplan-Meier estimates for local control were 97%; locoregional control, 94%; disease-specific survival, 80%; and overall survival, 85%. The overall functional laryngeal preservation rate was 79% (19 of 24). CONCLUSIONS: TLM is a safe and effective treatment for cancer of the supraglottic larynx. SIGNIFICANCE: TLM is an emerging strategy in the management of laryngeal cancer.     

Are solitary breast papillomas entirely benign?

HYPOTHESIS: Solitary breast papillomas are potentially malignant and are associated with a higher risk of breast cancer. DESIGN: Retrospective review of all pathological reports containing breast papilloma (1983-2000) and review of selected specimens. SETTING: Tertiary, referral, university-affiliated medical center. PARTICIPANTS: Ninety-five women with a breast specimen containing a papilloma or papillomatosis. Patients with overt papillary carcinoma without papilloma were excluded. INTERVENTION: All histopathological characteristics of the papilloma and the surrounding tissue were noted. The incidence of malignant and other proliferative histopathological findings were analyzed, comparing solitary ductal papilloma cases to multiple papilloma cases. The Fisher exact test and chi2 test were applied for statistical analysis. MAIN OUTCOME MEASURES: Surgical removal of solitary ductal papillomas should include margins wide enough to secure removal of any proliferative tissue within or around the papilloma and to enable thorough evaluation of the risk for future breast cancer. RESULTS: Solitary papillomas were associated with breast carcinoma in 7 patients (10%) in this series. An additional 9% (n = 6) presented with invasive or noninvasive carcinoma within the papilloma. Atypical papilloma was noted in 6% of patients (n = 4). The risk of associated malignancy was not significantly different between solitary ductal papilloma and multiple papilloma. CONCLUSION: Increased risk of breast cancer is associated with all forms of papilloma.     

Raman spectroscopy for neoplastic tissue differentiation: a pilot study

Background

Several changes occur during the transformation of normal tissue to neoplastic tissue. Such changes in molecular composition can be detected by Raman spectroscopy. Raman spectroscopy is a nondestructive method of measuring these changes, which suggests the possibility of real-time diagnosis during medical procedures.

Methods

This study seeks to evaluate the ability of Raman spectra to distinguish tissues. The Raman signatures of normal kidney, lung, and liver tissue samples from pigs and rats were characterized in vitro. Further, a human neuroblastoma and a hepatoblastoma, obtained at resection were also studied.

Results

The Raman spectra of the animal samples of kidney, liver, and lung are distinctly different in the intensity distribution of the Raman peaks. Further, the spectra of a given organ from pigs and rats, although similar, were different enough to distinguish between the 2 animals. In the patient tissues, the Raman spectra of normal liver, viable tumor, and fibrotic hepatoblastoma were very different. Fibrotic tissue showed a greater concentration of carotenoids, whereas viable tissue was rich in proteins and nucleic acids. The normal tissue showed both components. Similar differences were also seen in the neuroblastoma tissue.

Conclusions

The results of this study show the potential use of Raman spectroscopy in clinical diagnosis.     

Steroid hormone receptors in laryngeal carcinoma

The larynx has long been shown to be a target organ for androgenic steroids in both women and men, and specific androgen receptors have been determined in normal laryngeal mucosa and in laryngeal carcinoma tissue. In this study, samples from 21 primary laryngeal carcinomas, from 4 recurrent laryngeal carcinomas and from 1 cervical metastasis of laryngeal carcinoma were obtained at the time of surgery to assay specific androgen, estrogen, and progesterone receptors. Specific androgen receptors were found in 8 samples (31%). The level of receptors varied from 1.7 femtomoles (fmol) per milligram to 7.3 fmol/mg cytosol protein. Detectable levels of specific estrogen receptors were found in 18 samples (69%) and progesterone receptors in 8 of the 15 samples studied (53%). There was no apparent correspondence with donors' sex, since samples from both females and males contained all kinds of receptors. We know that antiestrogen inhibits the growth of squamous carcinoma cells lines positive for estrogen receptors in vitro and that this effect is reversible with the appropriate hormone. Thus, the relatively high percentage of estrogen and progesterone receptors found in laryngeal carcinoma tissue may open new aspects in the treatment of laryngeal carcinoma with antihormones.     

Culture of human laryngeal papilloma cells in vitro.

Human laryngeal epithelial cells have been grown in tissue culture in a hydrated collagen gel containing Nutrient Mixture F12 (Gibco) supplemented with 15% fetal calf serum and 10 micrograms/mL hydrocortisone. Primary cells often remain viable in culture for more than six months. They can be serially transferred two to four times before senescence. Cells derived both from normal epithelium and from laryngeal papilloma have been successfully cultured. Papilloma cells appear to contain more perinuclear granules and form fewer tight junctions than normal cells.     

Preliminary study of in vivo autofluorescence of nasopharyngeal carcinoma and normal tissue

BACKGROUND AND OBJECTIVE: In nasopharyngeal cancer, conventional white light endoscopy does not provide adequate information to detect the flat/small lesion and identify the margin of observable tumor. In the present study, we evaluate the potential of light-induced fluorescence spectroscopic imaging for the localization of cancerous nasopharyngeal tissue. STUDY DESIGN/MATERIALS AND METHODS: We built a multiple channel spectrometer specifically for the investigation of fluorescence collected by a conventional endoscopic system. Nasopharyngeal fluorescence were measured in vivo from 27 subjects during the routine endoscopy. The biopsy specimens for histologic analysis were taken from the tissue sites where the fluorescence were measured. RESULTS: Two algorithms to discriminate the nasopharyngeal carcinoma from normal tissue were created based on the good correlation between the tissue autofluorescence and histologic diagnosis. For the two-wavelength algorithm, carcinoma can be differentiated from normal tissue with a sensitivity and specificity of 93% and 92%, respectively. For the three-wavelength algorithm with compensation of variation of blood content in tissue, a sensitivity of 98% and specificity of 95% were achieved. CONCLUSION: Fluorescence endoscopic imaging used with the algorithms developed in this report is an efficient method for detecting the nasopharyngeal carcinoma.     

Raman molecular imaging: a novel spectroscopic technique for diagnosis of bladder cancer in urine specimens

Background

Raman molecular imaging (RMI) is an optical technology that combines the molecular chemical analysis of Raman spectroscopy with high-definition digital microscopic visualization. This approach permits visualization of the physical architecture and molecular environment of cells in the urine. The Raman spectrum of a cell is a complex product of its chemical bonds.

Objective

In this work, we studied the possibility of using the Raman spectrum of epithelial cells in voided urine for diagnosing urothelial carcinoma (UC).

Design, setting, and participants

Raman signals were obtained from UC tissue, then from UC touch preps obtained from surgical specimens and studied using the FALCON microscope (ChemImage, Pittsburgh, PA, USA), with a ×100 collection objective and green laser illumination (532 nm). Then, urine samples were obtained from 340 patients, including 116 patients without UC, 92 patients with low-grade tumors, and 132 patients with high-grade tumors. Spectra were obtained from an average of five cells per slide.

Measurements

Raman spectroscopy of cells from bladder cancer (BCa) tissues and patients.

Results and limitations

The Raman spectra from UC tissue demonstrate a distinct peak at a 1584 cm⁻¹ wave shift not present in benign tissues. The height of this peak correlated with the tumor's grade. The signal obtained from epithelial cells correctly diagnosed BCa with sensitivity of 92% (100% of the high-grade tumors), specificity of 91%, and a positive predictive value of 94% and a negative predictive value of 88%. The signal correctly assigned a tumor's grade in 73.9% of the low-grade tumors and 98.5% of the high-grade tumors. RMI for diagnosis of BCa is limited by the need for specialized equipment and training of laboratory personnel.

Conclusions

RMI has the potential to become a powerful diagnostic tool that allows noninvasive, accurate diagnosis of UC.     

Raman spectroscopy detects and distinguishes neuroblastoma and related tissues in fresh and (banked) frozen specimens

Background

Raman spectroscopy has been shown to accurately distinguish different neural crest-derived pediatric tumors. This study tests the ability of Raman spectroscopy to accurately identify cryopreserved tissue specimens using a classification algorithm designed from fresh tumor data and vice versa.

Methods

Fresh specimens of neuroblastoma and other pediatric neural crest tumors were analyzed with Raman spectroscopy. After analysis, the specimens were stored at −80°C. At a later date, the specimens were thawed and reanalyzed by Raman spectroscopy. A computer algorithm was used to classify the spectra from the frozen tissue against a computer model built on the fresh tissue data. This classification process was then reversed, testing fresh spectra against a model built from frozen data.

Results

We collected 1114 spectra (862 fresh and 252 frozen) from 62 tissue samples, including 8 normal adrenal glands, 29 neuroblastomas, 14 ganglioneuromas, 8 nerve sheath tumors, and 3 pheochromocytomas. At the tissue level, frozen neuroblastoma, ganglioneuroma, nerve sheath tumor, and pheochromocytoma were distinguished from normal adrenal tissue with 100% sensitivity and specificity. Fresh tissue had the same results except for the misclassification of one specimen of nerve sheath tumor.

Conclusions

The representative spectra show a high correlation between fresh and frozen tissue, and a clear difference between pathologic conditions. Spectra from frozen tissue can be accurately classified against spectra from fresh tissue and vice versa. This modality makes it possible to determine in a few minutes a result that often takes 12 to 36 hours for tissue processing and consideration by a trained pathologist to achieve.