Technetium-99m-MIBI in primary and recurrent head and neck tumors: Contribution of bone SPECT image fusion

We prospectively investigated 200 patients with the clinical suspicion for head and neck tumors. The final diagnoses were 94 primary and 56 (37 confirmed, 19 excluded) recurrent squamous cell carcinomas (SCCs), 3 primary and 7 (4 confirmed, 3 excluded) recurrent adenoid cystic carcinomas (ACCs), 6 non-Hodgkin's lymphomas, 10 distant metastases, 6 other malignancies, 10 inflammatory and 8 other nonmalignant conditions. Methods: Bone (600 MBq ^99mTc-3,3-diphosphono-1,2-propane dicarboxylic acid tetrasodium salt) and hexakis-2-methoxyisobutyl isonitrile (MIBI) (600 MBq ^99mTcMIBI) SPECT were both performed under identical conditions (triplehead gamma camera; ultra- high-resolution, parallel-hole collimators; three-dimensional postfiltering) and judged independently and after superimposition. The results were compared to the results of biopsy, surgery and CT. Results: The overall sensitivity/specificity of MIBI was 90%/78% for tumor detection and 90%/95% for the identification of malignant lymph node involvement (CT: 79%/66%, respectively 90%/79%). In the subgroup of recurrent SCC and ACC the sensitivity/specificity for tumor detection was 95%/71% for MIBI versus 78%/68% for CT. The isolated assessment of bone SPECT had a sensitivity/specificity of 100%/17% for osseous tumor spread. Image fusion of MIBI and bone SPECT differentiated between regio-local bone involvement and inflammatory changes and increased the specificity of bone SPECT to 100% in primary staging. Tumor size, stage, histology and pretreatment had no statistically significant effect on tracer uptake or diagnostic utility of scintigraphy. Conclusion: We propose the combined ^99mTc-MIBI and bone ultra-high resolution SPECT as a highly useful imaging approach in the primary and secondary staging in patients with suspected malignancies in the head and neck region. The high specificity for malignancies in the head and neck region may be used in the differential diagnosis between head and neck malignancies and inflammatory disease in patients with the accidental finding of enlarged lymph nodes and no clinical signs of a primary tumor. Image fusion with bone scanning is mandatory for the topographical orientation and increases the specificity of bone scanning to differentiate between inflammatory or malignant causes of increased bone metabolism.