Diagnostic usefulness of ¹8F-FAMT PET and L-type amino acid transporter 1 (LAT1) expression in oral squamous cell carcinoma.

PURPOSE: L-[3-(18)F]-α-Methyltyrosine ((18)F-FAMT) was developed as an amino acid tracer for PET imaging to provide better specificity than 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) PET for cancer diagnosis. We investigated the diagnostic usefulness of (18)F-FAMT in oral squamous cell carcinoma (OSCC). The correlation between tumour uptake of (18)F-FAMT and L-type amino acid transporter 1 (LAT1) expression was determined. METHODS: The study group comprised 68 OSCC patients who underwent both (18)F-FAMT and (18)F-FDG PET. Resected tumour sections were stained by immunohistochemistry for LAT1, CD98 and Ki-67, and microvessel density was determined in terms of CD34 and p53 expression. RESULTS: The sensitivity of primary tumour detection by (18)F-FAMT and (18)F-FDG PET was 98 % and 100 %, respectively. The sensitivity, specificity and accuracy of (18)F-FAMT PET for detecting malignant lymph nodes were 68 %, 99 % and 97 %, respectively, and equivalent values for (18)F-FDG PET were 84 %, 94 % and 94 %, respectively. The specificity and accuracy of (18)F-FAMT were significantly higher than those of (18)F-FDG. The uptake of (18)F-FAMT was significantly correlated with LAT1 expression, cell proliferation and advanced stage. The expression of LAT1 in OSCC cells was closely correlated with CD98 levels, cell proliferation and angiogenesis. CONCLUSION: (18)F-FAMT PET showed higher specificity for detecting malignant lesions than (18)F-FDG PET. The uptake of (18)F-FAMT by OSCC cells can be determined by the presence of LAT1 expression and tumour cell proliferation.

Clinical significance of ¹8F-α-methyl tyrosine PET/CT for the detection of bone marrow invasion in patients with oral squamous cell carcinoma: comparison with ¹8F-FDG PET/CT and MRI.

OBJECTIVE: L-3-[(18)F]-fluoro-α-methyl tyrosine ((18)F-FAMT) is an amino acid tracer for positron emission tomography/computed tomography (PET/CT) which specifically transported into cancer cells by L-type amino acid transporter 1 (LAT1). LAT1 overexpression in tumors is significantly correlated with cell proliferation and angiogenesis. (18)F-FAMT PET/CT, fluorine-18-fluorodeoxyglucose ((18)F-FDG) PET/CT and magnetic resonance imaging (MRI) were compared for their diagnostic performance in the detection of bone marrow invasion in patients with oral squamous cell carcinoma (OSCC). METHODS: Twenty-seven patients with OSCC on the upper or lower alveolar ridge underwent staging by MRI, (18)F-FDG PET/CT and (18)F-FAMT PET/CT studies before surgery. Post-surgical pathologic examination was used as the standard to determine the final diagnoses. The possibility of bone marrow invasion on MRI, (18)F-FDG PET/CT and (18)F-FAMT PET/CT were usually graded retrospectively into five-point score. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated according to the obtained scores. RESULTS: As the sensitivity of (18)F-FDG PET/CT was highest (100 %) among that of MRI (95 %) and (18)F-FAMT PET/CT (90 %), the specificity of (18)F-FAMT PET/CT was highest (85.7 %) among that of MRI (57 %) and (18)F-FDG PET/CT (14.3 %). The size of pathological tumor was accorded with that detected by (18)F-FAMT PET/CT and was smaller than that detected by (18)F-FDG PET/CT (P < 0.01). Significant difference was not found between (18)F-FAMT PET tumor volume and pathological tumor volume. CONCLUSIONS: (18)F-FAMT PET/CT was useful and more specific than MRI or (18)F-FDG PET/CT in the detection of bone marrow invasion of OSCC and may contribute to minimize the extent of resection in oral surgery patient.

Pulmonary artery intimal sarcoma: the role of ¹8F-fluorodeoxyglucose positron emission tomography in monitoring response to treatment.

We report the case of 58-year-old man with pulmonary artery intimal sarcoma. He initially presented with cough, right-sided chest pain, and shortness of breath. Although the diagnosis of pulmonary embolism had been considered, chest radiograph and pulmonary perfusion scintigraphy showed a mass in the right hilum and no perfusion in the right lung. (18)F-fluorodeoxyglucose positron emission computed tomography (FDGPET) showed increased FDG uptake in the mass obstructing the right pulmonary artery. Fine-needle biopsy revealed a pathological diagnosis of pulmonary artery intimal sarcoma. The patient was successfully treated with radiotherapy and adjuvant chemotherapy. FDG-PET was used for monitoring the response to therapy.

¹8F-FAMT uptake correlates with tumor proliferative activity in oral squamous cell carcinoma: comparative study with ¹8F-FDG PET and immunohistochemistry.

OBJECTIVE: L-3-[¹8F]-fluoro-α-methyl tyrosine (FAMT) is transported into cancer cells by L: -type amino acid transporter 1 (LAT1). The purpose of the present study is to correlate the uptake of FAMT and FDG with the cellular proliferative activity measured by the Ki-67 labeling index (Ki-67 LI) in oral squamous cell carcinoma (OSCC). METHODS: Twenty-five patients with OSCC were enrolled in this study. Both FAMT-PET and FDG-PET were performed within 4 weeks before surgery in all cases. The uptake of FAMT and FDG was compared by semiquantitative analysis with maximal standardized uptake values (SUVmax) of the primary tumors. Ki-67 LI of the tumors was analyzed by immunohistochemical staining and correlated with the clinicopathologic variables and the uptake of PET tracers. RESULTS: For primary tumor detection, FAMT-PET exhibited a sensitivity of 84%, whereas that of FDG-PET was 88%. In all visible lesions, mean FDG uptake determined by average SUVmax was 9.7 (range 4.2-15.9) and mean FAMT uptake was 3.5 (range 1.3-8.5). The SUVmax of FAMT tended to show a better correlation with Ki-67 LI (r = 0.878) than that of FDG (r = 0.643). CONCLUSIONS: Uptake of FAMT correlated with cellular proliferation of OSCC. FAMT-PET may be a useful procedure to evaluate tumor proliferation of OSCC.

Additional value of integrated PET/CT over PET alone in the initial staging and follow up of head and neck malignancy.

OBJECTIVE: Clinical application of FDG-PET in head and neck cancer includes identification of metastases, unknown primary head and neck malignancy, or second primary carcinoma, and also recurrent tumor after treatment. In this study, the additional value of PET/CT fusion images over PET images alone was evaluated in patients with initial staging and follow up of head and neck malignancy. METHODS: Forty patients with suspected primary head and neck malignancy and 129 patients with suspected relapse after treatment of head and neck malignancy were included. FDG-PET/CT study was performed after the intravenous administration of FDG (5 MBq/kg). Target of evaluation was set at primary tumor, cervical lymph node, and whole body. PET images and PET with CT fusion images were compared. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Results of PET and PET/CT were compared with postoperative histopathological examination, and case by case comparison of PET and PET/CT results for each region was performed. The additional value of CT images over PET only images was assessed. Statistical differences in sensitivity and specificity were evaluated. RESULTS: In the comparative evaluation of 507 targets by PET alone and PET/CT, 401 targets showed agreement of the results. Of the 106 discordant targets, 103 showed a positive result on PET alone and negative result on PET/CT. These results showed a significant difference (p< 0.01). Sensitivity of PET/CT was slightly higher than that of PET without statistical significance, while specificity of PET/CT was significantly higher than that of PET alone (Initial staging: 90.5% vs. 62.2%, p < 0.01; Follow up: 97.2% vs. 74.4%, p < 0.01). In Fisher's direct probability test, a significant difference was noted in the sensitivity (Initial staging: 91.3% vs. 87.0%, p < 0.01; Follow up: 93.9% vs. 91.4%, p <0.01). CONCLUSIONS: Combined PET/CT showed improved diagnostic performance than PET alone by decreasing the number of false positive findings in patients with initial staging and follow up of head and neck malignancy.