ABSTRACT
<p><b>OBJECTIVE</b>To investigate the value of single photon emission computed tomography(SPECT)-computed tomography(CT) in diagnosis of oral carcinoma invasion to mandible.</p><p><b>METHODS</b>Thirty-four patients with oral carcinoma invasion to mandible were divided into two groups, group A (surrounding invasion) and group B (central invasion). The edge of the invasion was evaluated by SPECT-CT, CT and pathological examination. The results of CT and SPECT-CT were analyzed by quantitative methods.</p><p><b>RESULTS</b>In group A, the cancer-invaded area of the mandible exhibited on SPECT-CT was 1.0 cm lager than that on pathological examination, 2.4 cm lager than that on CT. The difference of invaded area shown on CT was 1.4 cm smaller than that of pathological examination. There were significant difference among the three methods. In group B, the affected area on SPECT-CT was 1.2 cm lager than that of pathological examination, 4.2 cm lager than that of CT. The invision area on CT was 3.0 cm smaller than that of pathological examination. There were significant difference among the three methods.</p><p><b>CONCLUSIONS</b>SPECT-CT could find the jaw central tumor earlier than CT and the range of lesion showed by SPECT-CT was the adequate range of bone incision during operation. The range of lesion showed by CT was influenced by the type of tumor and the range of bone incision was determined according to the pathological type. If the false negative result was eliminated, only SPECT-CT or CT was needed to estimate the invasion range of mandible.</p>