Objective: A prospective study was designed to compare computer-aided 3-D 99mTc-DPD-SPECT (Technetium-Dicarboxy propan-single photon emission CT) reconstruction with clinical examination, panoramic radiography, CT scan and conventional 99mTc-DPD-SPECT investigation in the assessment of mandibular bone invasion by squamous cell carcinoma.
Patients and methods: Between October 1997 and December 1999, 88 patients with intraoral squamous cell carcinoma of the regions adjacent to the mandible were enrolled in this study. In 50 cases, mandibular resection (segmental or marginal) was performed based on the pre-treatment diagnostic results. Imaging studies were read independently by four experienced observers.
Results: No differences could be found between presurgical 3-D 99mTc-DPD-SPECT reconstruction and conventional 99mTc-DPD-SPECT investigation. Both techniques revealed a sensitivity of 100% whereas CT scan showed the greatest specificity (93.8%). SPECT investigation 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: This investigation does not provide evidence that 3-D 99mTc-DPD-SPECT reconstruction has any advantages when compared to conventional 99mTc-DPD-ECT investigation in the assessment of mandibular invasion by squamous cell carcinoma. Despite a sensitivity of 100% the specificity is still in need of improvement. Until newer methods or techniques become available the combination of CT scanning and conventional 99mTc-DPD-SPECT investigation appears to be the best means of detecting tumour invasion preoperatively and is thus helpful in directing appropriate surgical procedure.