METHODS: A 3-phase approach was undertaken: Phase 1: development of the weighted scoring system; Phase 2: estimating positive predicting value of MARK's Quadrant; and Phase 3: a) testing the validity of MARK's Quadrant in an open-access endoscope system; and b) comparing its usefulness compared to conventional referral system.
RESULTS: In phases 1 and 2, MARK's Quadrant with weighted symptoms was developed. The sensitivity of MARK's Quadrant is 88% and the specificity is 45.5% to detect cancerous and precancerous lesions of gastric. This was confirmed by the prospective data from phase 3 of this study where the diagnostic yield of MARK's Quadrant to detect any pathological lesion was 95.2%. This score has a high accuracy efficiency of 75%, hence comparing to routine referral system it has an odds ratio (95%CI) of 10.98 (4.63-26.00), 6.71 (4.46-10.09) and 0.95 (0.06-0.15) (P<0.001 respectively) for cancer, precancerous lesion and benign lesion diagnosis respectively.
CONCLUSION: MARK's Quadrant is a useful tool to detect early gastric cancer among symptomatic patients in a low incidence region.
METHODOLOGY: Jaw sections containing 67 teeth (86 roots) were collected from nine fresh, unclaimed bodies that were due for cremation. Imaging was carried out to detect AP lesions using film and digital PR with a centred view (FP and DP groups); film and digital PR combining central with 10˚ mesially and distally angled (parallax) views (FPS and DPS groups). All specimens underwent histopathological examination to confirm the diagnosis of AP. Sensitivity, specificity and predictive values of PR were analysed using rater mean (n = 5). Receiver operating characteristics (ROC) analysis was carried out.
RESULTS: Sensitivity was 0.16, 0.37, 0.27 and 0.38 for FP, FPS, DP and DPS, respectively. Both FP and FPS had specificity and positive predictive values of 1.0, whilst DP and DPS had specificity and positive predictive values of 0.99. Negative predictive value was 0.36, 0.43, 0.39 and 0.44 for FP, FPS, DP and DPS, respectively. Area under the curve (AUC) for the various imaging methods was 0.562 (FP), 0.629 (DP), 0.685 (FPS), 0.6880 (DPS).
CONCLUSIONS: The diagnostic accuracy of single digital periapical radiography was significantly better than single film periapical radiography. The inclusion of two additional horizontal (parallax) angulated periapical radiograph images (mesial and distal horizontal angulations) significantly improved detection of apical periodontitis.