Technetium 99m single positron emission computed tomography scanning for assessing mandible invasion in oral cavity cancer

Objectives: To study the accuracy of single positron emission computed tomo graphy (SPECT) scanning and compare its results to clinical examination, Pa norex, and computed tomography (CT) scanning with respect to determining ma ndibular invasion by oral cavity and oropharyngeal cancer, and to define th e role of SPECT scanning in the preoperative assessment of oromandibular ca ncer. Study Design: Prospective study of 38 patients who underwent techneti um 99m SPECT scanning as part of their preoperative clinical assessment for cancer at risk of invading the mandible. All patients underwent partial or segmental mandibulectomy as part of their surgical management. Methods: A data protocol was used to tabulate patient demographics, tumor characterist ics and results of preoperative tests as patients were enrolled into the st udy. Following surgical treatment, these data were correlated with histopat hological findings. Detailed analysis was performed to assess the tabulated data. Results: The SPECT scanning demonstrated an 87% overall accuracy in predicting bone invasion compared with 71% for clinical examination, CT sca nning, and Panorex x-rays. The SPECT scanning was significantly more sensit ive (95%) than either CT scans (55%) or Panorex x-rays (50%), Notably SPECT scanning demonstrated a considerable improvement in specificity (72%) comp ared with conventional radionuclide scanning. Although not as specific as C T scanning or plain films, SPECT scanning was significantly more effective in ruling out disease than was clinical examination. Conclusions: Preoperat ive SPECT scanning used in combination with clinical examination, CT scanni ng, and Panorex x-rays to assess patients at risk for mandible involvement by oral cavity cancer can improve the accuracy of predicting bone invasion and help in appropriate treatment planning so as to safely reduce the propo rtion of disease-free jaws resected.