The authors declare no competing interests associated with this report.
HRP was the project leader, had the idea to - and wrote the specs for the plugin, obtained the radiographic images, served as blind reader and wrote the article. GRT wrote the plugin and adapted it to ImageJ, assisted in obtaining the X-rays and was responsible for blinding them to the readers, secured and unblinded data and communicated with the statistician (LS). OCK, BFH and AMA were all blinded readers and participated in writing the manuscript. TAL was the radiological expertise, secured correct technique and participated in writing the manuscript. LS performed power calculations, statistics and participated in writing the manuscript. All authors read and approved the final manuscript.
The reproducibility of measurements on radiographs is influenced by the techniques by which the images as well as the measurements are obtained. Thus, bias resulting from errors in the image and/or image examinations at two points in time may result in wrongful registrations of true biological or pathological changes. The aim of the present study was to propose and evaluate an indirect radiological examination technique, by which bias, when measuring radiographic bone level, could be substantially reduced as compared to the technique using direct mm measurements.
A plugin to ImageJ was designed to reduce bias when measuring bone loss on radiographic images. In human dry mandibles, radiographic images of 20 teeth were obtained parallel with the tooth axis (alpha = 0) and at an angle of 30° deviation. The direct technique of measuring radiographic bone level (RBL) and the indirect, length-adjusted RBL were registered by four researchers in a double blinded fashion.
When mean RBL measured at 0° angle was 7.0 mm, the corresponding mean RBL measured at 30° angle was 7.8 mm, signifying an 11.4 % increase (p = 0.032), whereas the mean length-adjusted RBL increased by 0.6 % (p = 0.9).
This study showed that the use of the original, direct technique (ImageJ) resulted in markedly biased radiographic bone level at 30° angle, while the proposed indirect length-adjusted technique (ImageJ plugin) did not.
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- A new digital tool for radiographic bone level measurements in longitudinal studies
Hans R Preus
Gerald Ruiner Torgersen
Odd Carsten Koldsland
Bjørn Frode Hansen
Anne Merete Aass
Tore Arne Larheim
- BioMed Central
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