Computer-aided 3-D Tc-99m-DPD-SPECT reconstruction to assess mandibular invasion by intraoral squamous cell carcinoma: diagnostic improvement or not?

Objective: A prospective study was designed to compare computer-aided 3-D T c-99m-DPD-SPECT (Technetium-Dicarboxy propan-single photon emission CT) rec onstruction with clinical examination, panoramic radiography, CT scan and c onventional Tc-99m-DPD-SPECT investigation in the assessment of mandibular bone invasion by squamous cell carcinoma, Patients and Methods: Between Oct ober 1997 and December 1999, 88 patients with intraoral squamous cell carci noma of the regions adjacent to the mandible were enrolled in this study, I n 50 cases, mandibular resection (segmental or marginal) was performed base d on the pre-treatment diagnostic results. Imaging studies were read indepe ndently by four experienced observers, Results. No differences could be fou nd between presurgical 3-D Tc-99m-DPD-SPECT reconstruction and conventional Tc-99m-DPD-SPECT investigation. Both techniques revealed a sensitivity of 100% whereas CT scan showed the greatest specificity (93.8%), SPECT investi gation had a specificity of 91.6% and the greatest efficiency (95.4%), The greatest predictive positive value was found for CT scan (92.3%), Clinical examination and panoramic radiography displayed the lowest sensitivity, 82. 5% vs. 85.0%, and specificity, 79.2% vs, 89.5% respectively. Conclusion: Th is investigation does not provide evidence that 3-D Tc-99m-DPD-SPECT recons truction has any advantages when compared to conventional Tc-99m-DPD-ECT in vestigation in the assessment of mandibular invasion by squamous cell carci noma. Despite a sensitivity of 100% the specificity is still in need of imp rovement. Until newer methods or techniques become available the combinatio n of CT scanning and conventional Tc-99m-DPD-SPECT investigation appears to be the best means of detecting tumour invasion preoperatively and is thus helpful in directing appropriate surgical procedure. (C) 2000 European Asso ciation for Cranio-Maxillofacial Surgery.