The Universities of Utrecht and Nijmegen developed the Computer Aided Detection for TB tool in close cooperation with Rogan, University of Stellenbosch, Zambart and the Lung Institute of Cape Town. Partial financing for this scientific project was obtained from the Dutch Ministry of Economic Affairs with support from CheckTB!.

Computer Aided Diagnosis will enable automated accurate pre-screening on site by the digital X-ray system allowing radiologists or pulmonologists to focus more on analysing the TB suspect images. In addition CAD4TB will contribute to fewer "over-reading" by less experienced radiographers or clinical officers. This in combination with forwarding images for 2nd reading over low bandwidth mobile phone networks or the internet will innovate screening and early case detection in especially countries coping with limited resources, isolated health centres, risk groups and/or high co-infection with HIV. The UNION is involved in CAD4TB project progress updates and in the future chest image database management.

Possibilities for Future Use CAD4TB

To increase prevalence survey accuracy and to reduce cost of risk group screening programs CAD offers the following diagnostic functionality:

• provide a probability of abnormalities consistent with TB
• provide markers around suspect regions
• makes a color overlay for suspect regions
• integrated with CRRS scoring system
• select and present similar images for reference 

CAD4TB also allows for pre-selecting its sensitivity, which is of special value for prevalence surveys. Once the CAD4TB protocol is optimised it is expected the number of CXR requiring human reading can be reduced to less than 20%. For the moment in upcoming prevalence surveys where CAD4TB will be used dual reading (CAD and human) will done.

Basis for the revolution in diagnostics

In 2004, the Image Science Institute of the Medical Centre of Utrecht University and Rogan (both of the Netherlands) prepared a prototype software protocol able to recognise TB suspects in a database of 500 images with a sensitivity of 85% and a specificity of 50%. Valuable experience gained over the years from the development of accurate Computer Aided Detection of breast cancer, supporting mammography examinations, was used from the start.

The digital image can soon (last quarter of 2010) be interpreted on the spot within seconds by the CAD4TB protocol programmed to recognise image patterns consistent with TB. So digital Chest images can be read on the spot in real time by the CAD protocol, by the radiographer on a monitor or sent over any mobile phone or internet to any venue for second reading by a distant radiologist.

These are breakthrough new developments in boosting TB case detection using CXR and are welcomed by many institutions in Africa and leading TB organizations in the World like the UNION, WHO and the Dutch KNCV TB Foundation.

The progress!

The “Computer Aided Detection for TB (CAD4TB)” project is in full development. The University of Nijmegen is now involced on the Dutch side together with Rogan they collaborate with the University of Cape Town and the Desmond Tutu Lung Institute of the University of Stellenbosch (both of South Africa) and Zambart (Zambia) to further develop and scientifically proof this breakthrough diagnostic capability.

In order to achieve this, tens of thousands of digital images taken with the same technology direct digital X-ray systems will be analysed in the same systematic way. Various state-of-the-art pattern recognition techniques are applied to continuously improve sensitivity and specificity scores. While many of these images will be of healthy persons, a significant portion will come from TB patients that have also been diagnosed by culture, smear microscopy, clinical and other diagnostic methods.

The UNION will permanently be informed on developments in the study. At the 40^th World Conference of the UNION in Cancun the CAD4TB prototype was presented to various stakeholders like NTPs, NGOs, KNCV TB Foundation, WHO, UNION and FIND. At the TB Conference in Durban, South Africa in June 2010 the CAD4TB prototype will also be on display.

Expected Outcome

The objective of the joint research is to achieve an electronic TB screening capability with a sensitivity of 90% and a specificity of 80%. The specificity target will be the biggest challenge for the scientists. It is expected that on the basis of reading thousands of images (including access to patient information like HIV status), that patterns consistent with TB typical for co-infected patients will be found. This will further enhance the role of X-ray to effectively detect TB suspects in people living with HIV.

CAD improves TB screening and supports active case finding by:

A high percentage of TB suspect cases is identified easily wherever the digital camera is used.

- Supporting radiographers and/or clinical officers with first and immediate electronic image reading;
- Reducing number of human image interpretations or when used as second opinion reducing under and over reading;
- Providing a powerful tool in prevalence studies;
- Offering an effective quality assessment tool for health workers and NTP;
- Cutting screening and diagnostics costs.
(and will become available first with Odelca-DR in 2010 and other similar direct digital X-ray systems in about 18 months time)

The reference images (including data on smear microscopy and culture) available in the database will support radiographers to interpret Chest images on the spot with higher accuracy.

Only a limited number of complex Chest images will require external radiological expertise.

While developed for TB, this system can be enhanced in the future to spot other lung diseases as well. It is thus expected to contribute to a broad Healthcare strengthening impact in an area where this is most needed.

A Beta version of the new software is already available since March 2010. The full fledged version release is due for the last quarter of 2010.

Can your organization participate in the study?