68Ga-DOTATATE PET/CT in recurrent medullary thyroid carcinoma: a lesion-by-lesion comparison with 111In-octreotide SPECT/CT and conventional imaging.

PURPOSE: The aim of this study was to prospectively compare the detection rate of 68Ga-DOTATATE PET-CT with 111In-octreotide SPECT-CT and conventional imaging (CI) in medullary thyroid carcinoma (MTC) patients with increased calcitonin (Ctn) levels but negative CI after thyroidectomy. METHODS: Fifteen patients with raised Ctn levels and/or CI evidence of recurrence underwent 68Ga-DOTATATE PET-CT, 111In-octreotide SPECT-CT and CI. Histopathology, CI and biochemical/clinical/imaging follow-up were used as the reference standard. PET/CT, SPECT/CT and CI were compared in a lesion-based and organ-based analysis. RESULTS: PET/CT evidenced recurrence in 14 of 15 patients. There were 13 true positive (TP), 1 true negative (TN), 1 false positive (FP) and no false negative (FN) cases, resulting in a sensitivity and accuracy of 100% and 93%. SPECT/CT was positive in 6 of 15 cases. There were 6 TP, 2 TN, 7 FN and no FP cases, resulting in a sensitivity of 46% and accuracy of 53%. CI procedures detected tumor lesions in 14 of 15 patients. There were 13 TP, 1TN, 1 FP and no FN cases with a sensitivity of 100% and accuracy of 93%. A significantly higher number of lesions was detected by PET/CT (112 lesions, p = 0.005) and CI (109 lesions, p = 0.005) in comparison to SPECT/CT (16 lesions). There was no significant difference between PET/CT and CI for the total number of detected lesions (p = 0.734). PET/CT detected more lesions than SPECT/CT regardless of the organ. PET/CT detected more bone lesions but missed some neck nodal metastases evidenced by CI. The number of lesions per region demonstrated by PET/CT and CI were similar in the other sites. CONCLUSION: 68Ga-DOTATATE PET/CT is superior to 111In-octreotide SPECT/CT for the detection of recurrent MTC demonstrating a significantly higher number of lesions. 68Ga-DOTATATE PET/CT showed a superior detection rate compared to CI in demonstrating bone metastases.

Postsurgical imaging of the oral cavity and oropharynx: what radiologists need to know.

The oral cavity and oropharynx are common locations of neoplastic lesions; neoplasms at these sites are often treated with surgery. The goal of this surgical treatment is to achieve tumor control while preserving, whenever possible, the function of local structures. The procedure used depends largely on the location and extension of the tumor and the disease stage. Follow-up evaluation of patients is done with computed tomography (CT) and magnetic resonance (MR) imaging. The ability to interpret characteristic features at CT and MR imaging is particularly important because normal anatomic structures are altered in specific patterns according to the distinct surgical technique applied. Anatomic changes resulting from the most commonly performed procedures (eg, glossectomy, pelvectomy, and mandibulectomy) will be presented with CT and MR images, multiplanar reconstructions, and schematic illustrations. Understanding of postsurgical CT and MR imaging findings is important to avoid misinterpretation and confusion. Familiarity with the typical postsurgical imaging appearance of the oral cavity and oropharynx is crucial for differentiating normal postsurgical changes from persistent or recurrent disease and for diagnosis of associated second primary malignancies. Knowledge of postsurgical findings is essential for analysis of the oral cavity and oropharynx and allows early diagnosis of tumor recurrence or typical complications after surgical reconstruction.