Following a previous diagnostic assessment report (DG4),30National Institute for Health and Care Excellence (NICE) diagnostics guidance (DG4)31recommended using DySIS as an adjunct to colposcopy. ZedScan (Zilico Limited, Manchester, UK), previously known as APX100, was not included in the final guidance, as it had not received its Conformité Européenne (CE) mark prior to publication. Both DySIS and ZedScan are now being used in several hospitals in England and Wales.
Dynamic Spectral Imaging System with Dynamic Spectral Imaging System map (Dynamic Spectral Imaging System Medical)
Dynamic Spectral Imaging System is a high-resolution digital video colposcope. It also uses spectral imaging technology and an inbuilt algorithm to produce an adjunctive map of the cervical epithelium, which is known as the DySISmap (or pseudo-colour imaging). The DySISmap is intended to be used as an adjunct to colposcopy to assist clinicians in the diagnosis, biopsy and treatment of CIN.
The DySISmap maps the whitening effect following the application of acetic acid (acetowhitening) to the epithelium of the cervix in order to aid diagnosis, as well as selecting areas for biopsy and treatment. It does this by producing a quantitative measurement of the rate, extent and duration of acetowhitening, which is highly correlated with the altered structure and functionality of abnormal epithelial cells of the cervix. The DySISmap is produced during the period of the acetowhitening reaction. An inbuilt algorithm assigns each area of the cervix a colour on the DySISmap that corresponds to the likelihood of an
abnormality being present. The DySISmap is displayed on the screen, overlaid on a live image of the cervix. The colour spectrum ranges from cyan, which represents weak acetowhitening, to white, which represents intense acetowhitening; the greater the intensity of the measured acetowhitening reaction, the greater the likelihood of an abnormality. Imaging typically takes 3 minutes, and the average duration of use per examination is < 15 minutes.
BACKGROUND
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The manufacturer claims that new users can be trained to use DySIS in 2–4 hours (personal communication). Imaging takes 3 minutes and can be stopped manually; however, the company recommends at least 125 seconds of imaging to allow the system to calculate and display the DySIS map.32The list price for the latest version of DySIS (DySIS Touch colposcope) is £24,000 (personal communication). This is around twice the cost of a standard colposcope. The 5-year maintenance plan is an additional £6500, and the viewer licence is £650 in the first year and £500 per year in subsequent years. The DySIS includes a colposcope and no additional equipment is needed. The cost of specula is £3.50 per examination.33
The DySIS is CE marked and is developed by DySIS Medical. The currently available version of DySIS is DySIS version 3, but the company intends that it will be superseded by the DySIS Touch and DySIS Ultra colposcopes in early 2017. Each updated version of the system has had modifications to both the hardware and the software, but the DySISmap algorithm has remained unchanged.
ZedScan (Zilico)
ZedScan is an electrical impedance spectroscopy (EIS) device. It is designed to be used as an adjunct to colposcopy to aid in the diagnosis, biopsy and treatment of high-grade CIN. It applies a small alternating current at different frequencies to the cells lining the cervix and measures the resulting voltage. By using EIS, one can measure the resistivity of cervical epithelial cells to distinguish between normal and abnormal tissue. Electrical impedance is measured at 14 different frequencies, producing a spectrum that varies depending on the structure and properties of the tissue. The degree of impedance is related to tissue structure, which is classed as normal, precancerous or cancerous. A handset displays a diagram of the measurement zone by coloured circles that indicate the location and results from each measurement point:34
l clear/white – no reading
l green – high-grade CIN is unlikely to be present l amber – high-grade CIN is likely to be present
l red – the highest likelihood that high-grade CIN is present.
The results from each reading site are compared with reference spectra, derived from models of different cervical tissues, to calculate the probability of high-grade neoplasia. The device is also designed to indicate the location of high-grade CIN for biopsy. Further details on the ZedScan algorithm are reported in
Appendix 1.
The manufacturer estimates that each cervical scan using the ZedScan takes 2–3 minutes. The device can also be used in a single-point mode to help to select sites for diagnostic biopsy after the initial 10–12 readings have been taken. The manufacturer states that it takes approximately 2 hours to train the new users. ZedScan is CE marked and is developed by Zilico Ltd. ZedScan was previously known as APX100, which was the name used in the previous assessment (DG4).31The ZedScan costs £3000, including computer software. The cost per case with the ZedScan is approximately £30 plus clinician time. There are no routine maintenance costs.
The previous assessment (DG4)30found evidence to suggest that DySIS with DySISmap had higher sensitivity but lower specificity than colposcopy alone for detecting CIN 2+ disease, and it found limited evidence for other adjunctive technologies [LuViva Advanced Cervical Scan (developed by Guided
Therapeutics, Norcross, GA, USA) and Niris Imaging System (developed by Imalux Corporation, Cleveland, OH, USA)].
DOI: 10.3310/hta22540 HEALTH TECHNOLOGY ASSESSMENT 2018 VOL. 22 NO. 54
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Chapter 2 Definition of the decision problem
W
omen in England between the ages of 25 and 64 years are invited for regular cervical screening every 3–5 years in order to detect abnormal cells in the cervix. Screening is conducted using liquid-based cytology; women may also be tested for hrHPV.Depending on the results of the cervical screening, people may be referred for a colposcopy examination. Colposcopy is largely a subjective examination, and diagnosis will partly depend on the opinion and expertise of the colposcopist. The DySIS digital video colposcope with DySISmap and the ZedScan device have been developed to be used alongside colposcopy. The aim of these adjunctive technologies is to help the colposcopist to find abnormal cells more accurately. The DySIS system provides a coloured map of the cervix on a computer screen, on which different colours represent different risks of abnormal cells. ZedScan uses an electrical current to distinguish between normal and abnormal cells, and shows coloured circles on a diagram ranging from green (low risk of abnormal cells) to red (high risk of abnormal cells).
The DySIS was previously reviewed in the DG4 assessment.31However, additional information on this technology, the development of ZedScan since that review and recent changes in the NHSCSP mean that the relative value of using these new tests is uncertain.
This report, undertaken for the NICE Diagnostics Assessment Programme, examines the clinical effectiveness and cost-effectiveness of DySISmap and ZedScan used adjunctively alongside regular colposcopy for women referred for colposcopy as part of the cervical cancer screening programme.