The performance of Dynamic Spectral Imaging colposcopy depends on indication for referrals.

OBJECTIVE. A previous study has shown that Dynamic Spectral Imaging (DSI) colposcopy increases the sensitivity of the colposcopic examination in women referred with abnormal cytology. In this study we have reanalyzed the performance of DSI and conventional colposcopy for new referral conditions and for low-grade cytology referrals versus high-grade cytology referrals. METHOD. Data from a previous validation trial was used to assess the performance of DSI in different cytology groups:Women referred with BMD (borderline and mild dyskaryosis) cytology and women referred with NBMD cytology either hrHPV positive or negative were separately analyzed. Furthermore, we tried to assess the clinical performance by appropriate filtering of patients to replicate two different referral strategies. RESULTS. The sensitivity of DSI and conventional colposcopy to detect CIN2+ lesions in women referred with BMD cytology is 82% and 44% respectively (p= 0.001) and in the NBMD group 77% and 64% respectively (p= 0.24). If the two techniques are combined the sensitivity is 85%.When the conditions of new screening strategies are applied DSI colposcopy has a higher sensitivity to detect CIN2+ than conventional colposcopy. Findings are similar when CIN3+ is used as a threshold. CONCLUSION. We found that in most cases DSI colposcopy has a higher sensitivity than conventional colposcopy, even when referral criteria are changed. Unlike conventional colposcopy, the sensitivity of colposcopy with DSI in low-grade cytology referrals was found similar to the sensitivity in high-grade cytology referrals. This suggests that a baseline colposcopy sensitivity may be possible with the adjunctive use of the DSI map, irrespective of referral cytology.

Women's Preferences of Dynamic Spectral Imaging Colposcopy.

BACKGROUND: The focus of testing the dynamic spectral imaging (DSI) colposcope has been on the technical characteristics and clinical performance. However, aspects from a patient's perspective are just as important. METHODS: This study was designed as a substudy of the DSI validation study, a prospective comparative, multicenter clinical trial to assess the clinical performance of DSI colposcopy. All women included in this study were asked to complete two questionnaires: a patient characteristics questionnaire and a patient satisfaction questionnaire. RESULTS: In the initial study a total of 239 women were included in the intention-to-treat cohort. Of these, 230 women (96.2%) completed both questionnaires. When assessing the women's preferences for some of the possible uses of DSI colposcopy, a high level of agreement was noted for all potential implementations. In general, women found the additional time DSI colposcopy took acceptable: just 15 women (6.5%) thought the time DSI colposcopy took made them feel uncomfortable. Furthermore, women ranked test accuracy as the most important characteristic, followed by (more) rapid testing and comfort. Quick notification of the results and costs were considered the least important characteristics. CONCLUSION: Women are willing to accept discomfort in the form of an additional or longer test if there is clinical benefit.

Agreement between colposcopic impression and histological diagnosis among human papillomavirus type 16-positive women: a clinical trial using dynamic spectral imaging colposcopy.

OBJECTIVE: To investigate the agreement between conventional colposcopic impression, dynamic spectral imaging (DSI) colposcopy and histology, for human papillomavirus type 16-positive (HPV16(+)) and non-16 high-risk (hr) HPV(+) women. DESIGN: Prospective, comparative, multicentre clinical trial. SETTING: Three colposcopy clinics in the Netherlands. POPULATION: Women (n = 177) aged 18 years or over with an intact cervix, referred for colposcopy. METHODS: The colposcopist graded the lesion by using the DSI colposcope as a regular video colposcope. Subsequently the DSI impression was displayed and biopsies were taken from all abnormal areas as well as from a random (normal) site. A cervical smear was taken for HPV typing. MAIN OUTCOME MEASURES: Histologically confirmed high-grade cervical intraepithelial neoplasia or cancer (CIN2(+)), positive for HPV16 or for any other hrHPV type. RESULTS: The DSI colposcope identified more CIN2(+) cervical lesions among HPV16(+) women than in non-16 hrHPV(+) women (P = 0.032 regardless of final histology and P = 0.009 among women with CIN2(+)). Consequently, the sensitivity of the DSI colposcope for detecting CIN2(+) lesions was higher in HPV16(+) women than in non-16 hrHPV(+) women (97% versus 74%, P = 0.009). No such differences were seen for the colposcopist impression. In addition, mainly smaller cervical lesions are missed by the colposcopist. CONCLUSIONS: The sensitivity of DSI colposcopy for CIN2(+) is higher in HPV16(+) than in non-16 hrHPV(+) women. Furthermore, regardless of HPV16 status, the sensitivity of DSI for CIN2(+) is higher than that of the colposcopist, probably because colposcopists tend to miss smaller cervical lesions.

Dynamic spectral imaging colposcopy: higher sensitivity for detection of premalignant cervical lesions.

OBJECTIVE: to validate the dynamic spectral imaging (DSI) colposcope's colour-coded map in discriminating high- from low-grade cervical lesions and non-neoplastic tissue. DESIGN: prospective, comparative, multicentre clinical trial. SETTING: the colposcopy clinics of three Dutch hospitals. POPULATION: women of 18 years or over with an intact cervix, referred for colposcopy. METHODS: during a 3-minute image acquisition phase, the DSI colposcope was used as a regular video colposcope: the colposcopist located and graded potential lesions based on conventional colposcopic criteria. Subsequently, a colour-coded map was calculated and displayed, representing localisation and severity of the cervical lesion. Biopsies were collected from all atypical sites, as identified by digital mapping and/or conventional colposcopy. Furthermore, one additional biopsy was taken. MAIN OUTCOME MEASURES: histologically confirmed high-grade cervical disease (CIN2+). RESULTS: in total 275 women were included in the study: 183 women were analysed in the 'according-to-protocol' (ATP) cohort and 239 women in the 'intention-to-treat' (ITT) cohort. In the ATP cohort, the sensitivity of DSI colposcopy to identify women with high-grade (CIN2+) lesions was 79% (95% CI 70-88) and the sensitivity of conventional colposcopy was 55% (95% CI 44-65) (P = 0.0006, asymptotic McNemar test). When the DSI colour-coded map was combined with conventional colposcopy, the sensitivity was 88% (95% CI 82-95). CONCLUSIONS: DSI colposcopy has a significantly higher sensitivity to detect cervical lesions than conventional colposcopy. If the colour-coded map is combined with conventional colposcopic examination, the sensitivity increases further.

Energy transfer in the peridinin chlorophyll-a protein of Amphidinium carterae studied by polarized transient absorption and target analysis.

The peridinin chlorophyll-a protein (PCP) of dinoflagellates differs from the well-studied light-harvesting complexes of purple bacteria and green plants in its large (4:1) carotenoid to chlorophyll ratio and the unusual properties of its primary pigment, the carotenoid peridinin. We utilized ultrafast polarized transient absorption spectroscopy to examine the flow of energy in PCP after initial excitation into the strongly allowed peridinin S2 state. Global and target analysis of the isotropic and anisotropic decays reveals that significant excitation (25-50%) is transferred to chlorophyll-a directly from the peridinin S2 state. Because of overlapping positive and negative features, this pathway was unseen in earlier single-wavelength experiments. In addition, the anisotropy remains constant and high in the peridinin population, indicating that energy transfer from peridinin to peridinin represents a minor or negligible pathway. The carotenoids are also coupled directly to chlorophyll-a via a low-lying singlet state S1 or the recently identified SCT. We model this energy transfer time scale as 2.3 +/- 0.2 ps, driven by a coupling of approximately 47 cm(-1). This coupling strength allows us to estimate that the peridinin S1/SCT donor state transition moment is approximately 3 D.

An unusual pathway of excitation energy deactivation in carotenoids: singlet-to-triplet conversion on an ultrafast timescale in a photosynthetic antenna.

Carotenoids are important biomolecules that are ubiquitous in nature and find widespread application in medicine. In photosynthesis, they have a large role in light harvesting (LH) and photoprotection. They exert their LH function by donating their excited singlet state to nearby (bacterio)chlorophyll molecules. In photosynthetic bacteria, the efficiency of this energy transfer process can be as low as 30%. Here, we present evidence that an unusual pathway of excited state relaxation in carotenoids underlies this poor LH function, by which carotenoid triplet states are generated directly from carotenoid singlet states. This pathway, operative on a femtosecond and picosecond timescale, involves an intermediate state, which we identify as a new, hitherto uncharacterized carotenoid singlet excited state. In LH complex-bound carotenoids, this state is the precursor on the reaction pathway to the triplet state, whereas in extracted carotenoids in solution, this state returns to the singlet ground state without forming any triplets. We discuss the possible identity of this excited state and argue that fission of the singlet state into a pair of triplet states on individual carotenoid molecules constitutes the mechanism by which the triplets are generated. This is, to our knowledge, the first ever direct observation of a singlet-to-triplet conversion process on an ultrafast timescale in a photosynthetic antenna.