[99mTc-MDP-SPECT for detection of subclinical mandibular infiltration of squamous epithelial carcinoma].

UNLABELLED: A prospective study was performed to compare the sensitivity and accuracy of ultrasound (US), computed tomography (CT), and single photon emission computed tomography (SPECT) as a bone scan to detect subclinical invasion of the mandible by squamous cell carcinoma of the oral cavity and floor of mouth.

METHODS

The present study reports data on 35 patients with squamous cell carcinoma of the oral cavity. SPECT, mandibular orthopantomography (OPG), US, CT and magnetic resonance imaging (MRI) were performed as well as histologic examination of resected mandibles. Transverse slices of 12 mm thickness were reconstructed for SPECT and semi-quantitative assessment of radionuclide uptake was performed with a scoring system based on comparisons of tracer uptake in the mandible to that in an unaffected part of the mandible. Lesion to non-lesion count ratios in the mandible in 3 h SPECT images were calculated. OPG, US and CT were evaluated for comparison.

RESULTS

In 12/35 patients, histologic examination showed carcinoma infiltrating mandibular bone. SPECT correctly predicted mandibular invasion in 11/12 cases, with no false-positive results. CT detected correctly 3/12 lesions, while OPG and ultrasound each demonstrated 2/12 tumors.

CONCLUSION

Bone SPECT was found to provide an accurate means for assessing tumor invasion to the mandible by intraoral squamous cell carcinoma. As a complementary study to one of the other imaging modalities it was shown to have a high specificity, indicating that it should be performed routinely in patients with suspect mandibular bone involvement by causes.