Abstract
Aims: To evaluate the postulate that a combination of x-ray mammography (XMM) and scintimammography (SMM) using receiver operatinq characteristic (ROC) statistical technique is better than either imaging used alone in the diagnosis of early breast cancer.

Methods: A cohort of 27 patients with 30 breast tumours was studied prospectively. The patients underwent a clinical examination, XMM,j and SMM, followed by fine needle biopsy/excision biopsy. The findings on XMM and SMM were divided into five grades: (1) probably normal, (2) probably benign, (3) equivocal, (4) probably malignant and (5) definitely malignant. Sensitivity and specificity were determined and ROC curves were drawn for XMM and SMM and compared against combined XMM and SMM.

Results: The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for XMM were calculated at 77%, 82%, 77% and 82% respectively; 85%, 94%, 92% and 89% for SMM; and for combined XMM and SMM, the values were 92%, 94%, 92% and 94% respectively. ROC curves were drawn and analysis of areas under ROC curves yielded values for XMM, SMM and combined imaging (XMM+SMM) at 0.85, 0.90 and 0.93 respectively. Wilcoxon signed ranked test showed that p value for XMM and result of combination images (XMM+SMM) was close to significant at 95% confidence level (i.e. 0.06) and the p value for SMM and combination imaqes (XMM+SMM) was also close to significant at 95% confidence level (i.e. 0.062). The p value for XMM and SMM was not significant.

Conclusion: The study shows that a combination of XMM and SMM, is more accurate in the diagnosis of early breast cancer than XMM or SMM alone. The study further suggests a role for SMM in equivocal breast lesions documented on XMM.