Comparison of preprocessing techniques to reduce nontissue-related variations in hyperspectral reflectance imaging

Significance: Hyperspectral reflectance imaging can be used in medicine to identify tissue types, such as tumor tissue. Tissue classification algorithms are developed based on, e.g., machine learning or principle component analysis. For the development of these algorithms, data are generally preprocessed to remove variability in data not related to the tissue itself since this will improve the performance of the classification algorithm. In hyperspectral imaging, the measured spectra are also influenced by reflections from the surface (glare) and height variations within and between tissue samples.Aim: To compare the ability of different preprocessing algorithms to decrease variations in spectra induced by glare and height differences while maintaining contrast based on differences in optical properties between tissue types.Approach: We compare eight preprocessing algorithms commonly used in medical hyperspectral imaging: standard normal variate, multiplicative scatter correction, min-max normalization, mean centering, area under the curve normalization, single wavelength normalization, first derivative, and second derivative. We investigate conservation of contrast stemming from differences in: blood volume fraction, presence of different absorbers, scatter amplitude, and scatter slope-while correcting for glare and height variations. We use a similarity metric, the overlap coefficient, to quantify contrast between spectra. We also investigate the algorithms for clinical datasets from the colon and breast.Conclusions: Preprocessing reduces the overlap due to glare and distance variations. In general, the algorithms standard normal variate, min-max, area under the curve, and single wavelength normalization are the most suitable to preprocess data used to develop a classification algorithm for tissue classification. The type of contrast between tissue types determines which of these four algorithms is most suitable

[Carcinoma of the fallopian tube after prophylactic laparoscopic ovariectomy in a patient with a BRCAI mutation]

A 48-year-old woman with a distended abdomen appeared to have ascites and was admitted to the gynaecological ward. At the age of 31 years she had been diagnosed with breast cancer and had undergone surgical breast conservation of the right breast. There was a history of both ovarian cancer and breast cancer in her family. Genetic evaluation showed that she was carrying a BRCAI germline mutation. At the age of 42 years she underwent a prophylactic bilateral laparoscopic ovariectomy and 5 years later she underwent a complete mastectomy due to breast carcinoma of the left breast. Two months later she developed ascites, a raised CA125 level and on a CT scan carcinoma of the peritoneum. During the laparotomy a fallopian tube carcinoma was found. After the uterus, fallopian tubes and omentum had been surgically removed, chemotherapy took place. The patient tolerated this well and the CA125 value decreased. Recently, the first molecular evidence was found that linked fallopian tube cancer to germline mutations in BRCAI patients. Patients harbouring a BRCA germline mutation not only have an increased risk of ovarian carcinoma but also of fallopian tube carcinoma. Therefore, in patients with a BRCA mutation, prophylactic surgery should take the form of an adnexectomy, not an oophorectomy

Evaluation of the Risk of Malignancy Index in daily clinical management of adnexal masses.

Contains fulltext : 88649.pdf (publisher's version ) (Closed access)OBJECTIVE: To verify the effectiveness of the Risk of Malignancy Index in the discrimination between non-invasive (benign and borderline) lesions and invasive malignant adnexal masses in daily clinical practice. METHODS: This prospective observational study was conducted in a multicentre cooperation of 11 hospitals. A total of 548 women with adnexal masses were included. Ultrasound characteristics, menopausal status and serum CA 125 level were registered preoperatively, and combined into the RMI afterwards. Final diagnosis was based on routine histopathologic examination. The decision to have patients operated by or with a gynecologic oncologist was based on the clinical impression of the gynecologist in the local hospital, based on physical examination, testing of serum samples, and ultrasound examination. This was compared with the hypothetical situation in which the RMI would have been applied as method of selection. RESULTS: An RMI of 200 achieved a sensitivity of 81% and specificity of 85% in the detection of ovarian cancer. Positive and negative predictive values were 48% and 96% respectively. In current practice, 64% of ovarian cancer patients were operated by a gynecologic oncologist. This percentage would have increased to 80% if the RMI with a cutoff value of 200 would have been used as method of selection. CONCLUSIONS: In our study population, introduction of the RMI would improve the management of adnexal masses, with a higher percentage of ovarian cancer patients that are operated by a gynecologic oncologist. At the same time, referral of patients with non-invasive (benign and borderline) lesions would be reduced.1 maart 201

Colourimetric analysis of thermally altered human bone samples

At this moment, no method is available to objectively estimate the temperature to which skeletal remains have been exposed during a fire. Estimating this temperature can provide crucial information in a legal investigation. Exposure of bone to heat results in observable and measurable changes, including a change in colour. To determine the exposure temperature of experimental bone samples, heat related changes in colour were systemically studied by means of image analysis. In total 1138 samples of fresh human long bone diaphysis and epiphysis, varying in size, were subjected to heat ranging from room temperature to 900 °C for various durations and in different media. The samples were scanned with a calibrated flatbed scanner and photographed with a Digital Single Lens Reflex camera. Red, Green, Blue values and Lightness, A-, and B-coordinates were collected for statistical analysis. Cluster analysis showed that discriminating thresholds for Lightness and B-coordinate could be defined and used to construct a model of decision rules. This model enables the user to differentiate between seven different temperature clusters with relatively high precision and accuracy. The proposed decision model provides an objective, robust and non-destructive method for estimating the exposure temperature of heated bone samples

Use of risk of malignancy index to indicate frozen section analysis in the surgical care of women with ovarian tumors

OBJECTIVE: To evaluate the importance of the risk of malignancy index (RMI) in the decision to perform frozen section analysis among women with ovarian tumors. METHODS: A retrospective study was conducted in 11 centers in the Netherlands. Women who underwent surgical treatment of an ovarian mass with unknown histology between January 2005 and September 2009 were included. The RMI was calculated retrospectively. Frozen section analysis and RMI values were assessed for patients with benign, borderline, and malignant ovarian tumors on final histopathology. RESULTS: Overall, 670 women were included. Frozen sections were performed in 323 (48.2%) patients, of whom 206 (63.8%) were diagnosed with benign ovarian tumors, 55 (17.0%) with borderline tumors, and 62 (19.2%) with malignant tumors. Overall, 109 (16.3%) women had an RMI below 20, 106 (97.2%) of whom had benign histology results. Among 235 patients with an RMI over 100, 3 (1.3%) postmenopausal women had malignancies that were missed because frozen sections were not performed. CONCLUSION: Women with an RMI below 20 have a low risk of malignancy and therefore do not require frozen section analysis. Postmenopausal women with an RMI greater than 100 should be referred to centers where frozen sections can be performed, and proper facilities and expertise are available to perform staging procedures if necessary

External validation of the adapted Risk of Malignancy Index incorporating tumor size in the preoperative evaluation of adnexal masses.

Item does not contain fulltextOBJECTIVE: The Risk of Malignancy Index (RMI) is a simple scoring system to standardize and improve the preoperative evaluation of adnexal masses. Since 1990, three versions of the RMI have been validated in different clinical studies. Recently, a fourth version of the RMI (RMI-4) was introduced that includes tumor size as an additional parameter. The aim of this study was to validate the ability of RMI-4 to discriminate between non-invasive lesions and invasive malignant adnexal masses, and to compare its performance with RMI-3. STUDY DESIGN: Women scheduled for surgery for an adnexal mass between 2005 and 2009 in 11 hospitals were included. Ultrasonographic characteristics, menopausal status and serum CA 125 level were registered preoperatively, and combined into the RMI. The performances of RMI-3 and RMI-4 were assessed and statistically tested for differences. RESULTS: A total of 643 patients were included: 469 benign, 73 borderline and 101 malignant tumors. The RMI-3 had a sensitivity of 76%, specificity of 82%, positive and negative predictive values (PPV and NPV) of 45% and 95%, and an accuracy of 81%. The RMI-4 had a sensitivity of 74%, specificity of 79%, PPV of 40%, NPV of 94%, and an accuracy of 78%. The accuracy of RMI-3 was significantly higher than the accuracy of RMI-4 (p=.001). Both models had an area under the curve of 0.86. CONCLUSION: Both RMI-3 and RMI-4 were able to discriminate between non-invasive lesions and invasive malignant adnexal masses, with similar performances. Including tumor size in the RMI does not improve its performance

Preoperative CA-125 predicts extra-uterine disease and survival in uterine papillary serous carcinoma patients

Item does not contain fulltextObjective: We determined the clinical utility of preoperative serum CA-125 as predictor of extra-uterine disease and as prognosticator for survival in patients with uterine papillary serous carcinoma (UPSC).Methods: Patients diagnosed with UPSC, identified between 1992 and 2009, and with preoperative CA-125 measurement were included. A receiver operator characteristic (ROC) curve was used to quantify marker performance. Overall and progression free survival were analyzed using the Kaplan-Meier method. Regression analyses were used to investigate the association of preoperative CA-125 levels and other clinicopathological variables with the presence of extra-uterine disease and the effects on survival.Results: Sixty-six patients met the study criteria. Using ROC, the CA-125 concentration of 45 U/mL as cutoff level provided the best sensitivity (75%) and specificity (74%) for extra-uterine disease, with a positive predictive value of 86%. Survival was significantly longer in patients with preoperative CA-125 </=45 U/mL (p&lt;0.001). Only preoperative CA-125 &gt;45 U/mL remained significantly associated with extra-uterine disease (OR=6.30, 95% CI 1.93-20.62). Furthermore, advanced FIGO stage (HR=4.53, 95% CI 1.50-13.62) and preoperative CA-125 &gt;45 U/mL (HR=3.12, 95% CI 1.13-8.73) were associated with decreased survival.Conclusion: Preoperative elevated serum CA-125 is an independent predictor for the presence of extra-uterine disease and an independent risk factor for survival in UPSC patients

Linking minimum inhibitory concentrations to whole genome sequence-predicted drug resistance in Mycobacterium tuberculosis strains from Romania

Mycobacterium tuberculosis drug resistance poses a major threat to tuberculosis control. Current phenotypic tests for drug susceptibility are time-consuming, technically complex, and expensive. Whole genome sequencing is a promising alternative, though the impact of different drug resistance mutations on the minimum inhibitory concentration (MIC) remains to be investigated. We examined the genomes of 72 phenotypically drug-resistant Mycobacterium tuberculosis isolates from 72 Romanian patients for drug resistance mutations. MICs for first- and second-line drugs were determined using the MycoTB microdilution method. These MICs were compared to macrodilution critical concentration testing by the Mycobacterium Growth Indicator Tube (MGIT) platform and correlated to drug resistance mutations. Sixty-three (87.5%) isolates harboured drug resistance mutations; 48 (66.7%) were genotypically multidrug-resistant. Different drug resistance mutations were associated with different MIC ranges; katG S315T for isoniazid, and rpoB S450L for rifampicin were associated with high MICs. However, several mutations such as in rpoB, rrs and rpsL, or embB were associated with MIC ranges including the critical concentration for rifampicin, aminoglycosides or ethambutol, respectively. Different resistance mutations lead to distinct MICs, some of which may still be overcome by increased dosing. Whole genome sequencing can aid in the timely diagnosis of Mycobacterium tuberculosis drug resistance and guide clinical decision-making

Efficacy of a Regional Network for Ovarian Cancer Care

Contains fulltext : 127298.pdf (publisher's version ) (Closed access)OBJECTIVE:: To study the influence of a regional collaboration in epithelial ovarian cancer care on staging procedures, debulking results, and survival. METHODS:: In an effort to optimize epithelial ovarian cancer treatment, a regional collaboration was introduced in the Netherlands in 2000. Gynecologic oncologists from the university center conducted surgery in community hospitals when ovarian cancer was considered based on the risk of malignancy index or clinical suspicion. The National Cancer Registry registered 1,554 patients with epithelial ovarian cancer diagnosed in 11 participating Dutch hospitals between 1996 and 2010. Surgical procedures were compared during three periods (1996-1999, 2000-2004, and 2005-2009). Log-rank tests compared Kaplan-Meier survival curves of progression-free and overall survival before (1996-2000) and during the start of the collaboration (2001-2005). RESULTS:: Staging was adequate for 139 patients (23.0%) before collaboration, and this proportion increased during the study periods to 32.1% and 62.1% (P<.01), when gynecologic oncologists more often staged cancer in patients (36.7% compared with 54.7% and 80.6%; P<.01). For 1,197 patients with advanced stage disease (stage IIb or greater), the proportion of debulking procedures with an optimal (residual volume less than1 cm) as well as a complete result (no residuals) increased during the 14-year study period from 57.4% to 76.5% (P<.01) and from 24.1% to 43.4% (P<.01), respectively. Survival rates were similar before and during the start of the collaboration. In multivariable analysis, the treatment variables completeness of debulking, chemotherapy, and gynecologic oncologist attendance were independent prognostic factors for overall survival, as were age, stage, and tumor grade. CONCLUSIONS:: After regional collaboration, gynecologic oncologists attended more surgeries and surgical outcomes improved, but progress in survival could not be demonstrated. Regional collaboration improved care for ovarian cancer patients. LEVEL OF EVIDENCE:: II