carbon-11-methionine and Lung-Neoplasms

This study was performed to investigate the feasibility of FDG- and L-[methyl-11C]methionine (Met)-PET for the follow up of lung cancer after stereotactic radiotherapy (SRT). Nine patients (pt) with solitary lung cancer underwent SRT. Met- and FDG-PET studies were performed one week before SRT and from one week to 8 months after SRT. Responses to SRT were complete in 2 pt and partial in 7 pt. Met- and FDG-PET scan showed high tracer uptake in all tumors before SRT. After SRT, standardized uptake values (SUV) of FDG and Met changed concordantly. Both decreased with time in 5 pt but did not decrease steadily in 4 pt, where 2 pt showed an increase at 1 to 2 weeks after SRT and 2 pt showed an increase at more than 3 months after SRT. The former appears to reflect the acute reaction to SRT and the latter radiation-induced pneumonitis. Although the addition of Met-PET did not provide additional information over FDG-PET, FDG- and Met-PET could be used to evaluate the treatment effect of SRT.

Topics: Aged; Aged, 80 and over; Female; Fluorodeoxyglucose F18; Humans; Image Enhancement; Lung Neoplasms; Male; Methionine; Middle Aged; Positron-Emission Tomography; Prognosis; Radiopharmaceuticals; Radiosurgery; Reproducibility of Results; Sensitivity and Specificity; Solitary Pulmonary Nodule; Treatment Outcome

To evaluate the ability of 11C-methionine positron emission tomography (MET-PET) to delineate target volumes for brain metastases and to investigate to what extent tumor growth is presented by magnetic resonance imaging (MRI) and MET-PET.. Three observers undertook target definition in 19 patients with 95 brain metastases by MRI and MET-PET images. MRI gross target volume (GTV) (GTV-MRI) was defined as the contrast-enhanced area on gadolinium-enhanced T1-weighted MRI. MET-PET GTV (GTV-PET) was defined as the area of an accumulation of MET-PET apparently higher than that of normal tissue on MET-PET images. The size of occupation ratio was determined using the following equation: SOR (%) of MET are within x mm margin outside GTV-MRI = the volume of the GTV-PET within x mm outside the GTV-MRI/the volume of the GTV-PET.. For GTV-MRI volumes of 0.5 mL, GTV-PET volumes were larger than GTV-MRI volumes and a significant correlation was found between these variables by linear regression. For all tumor sizes and tumor characteristics, a 2-mm margin outside the GTV-MRI significantly improved the coverage of the GTV-PET.. Although there were some limitations in our study associated with spatial resolution, blurring effect, and image registrations with PET images, MET-PET was supposed to have a potential as a promising tool for the precise delineation of target volumes in radiotherapy planning for brain metastases.

Topics: Aged; Aged, 80 and over; Brain Neoplasms; Breast Neoplasms; Carbon Radioisotopes; Carcinoma, Non-Small-Cell Lung; Female; Gadolinium; Humans; Lung Neoplasms; Magnetic Resonance Imaging; Male; Methionine; Middle Aged; Positron-Emission Tomography; Sensitivity and Specificity; Tumor Burden

To differentiate between benign and malignant lesions of the lung, 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) has limitations such as a lower specificity in cases of non-specific inflammation. The positive predictive value is unsatisfactory in countries where inflammatory lung disorders are prevalent. We present the preliminary results of the usefulness of combining 11C-methionine-PET and 18F-FDG-PET in this context.. Fifteen patients with indeterminate solitary pulmonary nodules/masses (10 men, 5 women; average age 64.7 +/- 14.0 years, ranging from 25 to 87 years) were studied using 11C-methionine- and 18F-FDG-PET. Interpretations were primarily made on visual analysis with five-point scale and a consensus of two nuclear medicine physicians, using standardized uptake value as an accessory reference. Foci of abnormal radiotracer uptake were subsequently correlated with clinical follow-up, imaging modalities such as chest radiography, chest computed tomography (CT), serial PET studies, and pathology results from bronchoscopic biopsy and/or surgical specimen.. Diagnoses were established in 14 patients. The 11C-methionine-PET and 18F-FDG-PET studies were both true positive in two cases of adenocarcinoma and true negative in two cases of clinical benign nodules. In one case of lymphoid hyperplasia both 11C-methionine-PET and 18F-FDG-PET showed false-positive findings. Discordant results were obtained in nine cases. In spite of the false-positive results of 18F-FDG-PET, 11C-methionine-PET was true negative in four cases with chronic inflammatory nodules and three cases of pulmonary tuberculosis. Furthermore, (11)C-methionine-PET was true positive in one case of lung metastasis of thyroid cancer, and in another with recurrence of gastric cancer, respectively, for which 18F-FDG-PET imaging was false negative.. Our experience indicates that 11C-methionine-PET seems more specific and sensitive when compared with 18F-FDG-PET for the purpose of differentiating benign and malignant thoracic nodules/masses. The possibility of an FDG-avid lesion being malignant is decreased if it shows a negative result by 11C-methionine-PET.

Topics: Adult; Aged; Aged, 80 and over; Feasibility Studies; Female; Fluorodeoxyglucose F18; Humans; Lung Neoplasms; Male; Methionine; Middle Aged; Positron-Emission Tomography; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Solitary Pulmonary Nodule

Topics: Carbon Radioisotopes; Humans; Lung Neoplasms; Lymph Nodes; Lymphatic Metastasis; Methionine; Neoplasm Staging; Radiopharmaceuticals; Sensitivity and Specificity; Tomography, Emission-Computed; Tomography, X-Ray Computed

We retrospectively evaluated the usefulness of PET with 11C-methionine (methionine PET) for the diagnosis of lymph node metastases in patients with lung cancer.. Methionine PET and CT were performed before surgical intervention in 41 patients with primary lung cancer. We evaluated individual lymph nodes by methionine PET along with corresponding CT images. The 11C-methionine accumulation of lymph nodes was assessed semiquantitatively by analysis of the tumor-to-muscle ratio (TMR) and was compared with CT and histological diagnoses.. A total of 126 lymph nodes, 36 of which were histologically diagnosed as metastatic, were assessed by CT and methionine PET. The TMR in metastatic lymph nodes (n = 36) was 5.15+/-1.69, whereas that of nonmetastatic lymph nodes (n = 90) was 2.91+/-0.76; this difference was significant (P < 0.0001). The most adequate TMR cutoff value for diagnosis of metastasis based on the results of receiver operating characteristic curve analysis was 4.1. The positive and negative predictive values, sensitivity, specificity, and accuracy of methionine PET were 79.5%, 94.3%, 86.1%, 91.1%, and 89.7%, respectively, and were superior to those of CT (57.6%, P = 0.04; 81.7%, P = 0.008; 52.8%, P = 0.002; 84.4%, NS; and 75.4%, P = 0.002, respectively). All positive nodes that were shown to be true-positive by CT, and 12 of 17 false-negatives on CT were correctly diagnosed by PET. Ten of 14 lymph nodes that were false-positive on CT were also correctly diagnosed by PET.. Methionine PET appears to be superior to CT for the diagnosis of lymph node metastasis in lung cancer patients. The high negative predictive value of methionine PET suggests that cases in which lymph nodes are enlarged on CT with negative PET analysis may be diagnosed as negative for metastasis.

Topics: Carbon Radioisotopes; Female; Humans; Lung Neoplasms; Lymph Nodes; Lymphatic Metastasis; Male; Methionine; Middle Aged; Predictive Value of Tests; Radiopharmaceuticals; Retrospective Studies; ROC Curve; Sensitivity and Specificity; Tomography, Emission-Computed; Tomography, X-Ray Computed

We evaluated the value of PET using 18F-fluorodeoxyglucose (FDG) and 11C-methionine, individually or in combination, to distinguish malignant from benign tumors and to identify or exclude mediastinal metastases.. Seventeen patients with a tumor in the lung or mediastinum were evaluated with 18F-FDG and 11C-methionine PET. For morphological comparison, we used CT, and all findings were confirmed by histology of surgical resection specimens (n = 16) or by cytology (n = 1).. All tumors were visualized equally well with both tracers, and there were no false-positive results. In 2 patients with a malignant tumor, coexisting pneumonia was correctly diagnosed as an inflammatory lesion because of its wedge-like shape. PET correctly excluded hilar invasion and mediastinal lymph node metastases in 10 of 14 patients with primary lung tumor. PET identified mediastinal metastases in 4 of 4 patients. CT failed to detect mediastinal tumor spread in 2 patients and gave a false-positive reading in 2 others. Significantly higher uptake (SUV) and transport rate (slope) values were obtained from malignant than benign lesions with both tracers. No major differences were seen in either the levels of significance or accuracy when the two tracers were compared. Slope values did not add further information to what was obtained with SUV. Density correction of SUV and slope values, to avoid the influence of surrounding air as well as tumor heterogeneity, increased these differences somewhat. Both tracers distinguished malignant from benign lesions with a 93% sensitivity and an accuracy of 89%-95%, but sensitivity improved to 100% when values from both tracers were combined.. Fluorine-18-FDG and 11C-methionine PET visualized all tumors equally well and detected mediastinal spread better than CT. For differentiation purposes, the problems of false-positive and false-negative PET findings could not be safely overcome in a limited number of cases either by the use of both tracers, by the additional use of slope values or by lesion density correction.

Topics: Aged; Carbon Radioisotopes; Female; Fluorodeoxyglucose F18; Humans; Image Processing, Computer-Assisted; Lung Neoplasms; Male; Mediastinal Neoplasms; Methionine; Middle Aged; Radiopharmaceuticals; Sensitivity and Specificity; Tomography, Emission-Computed; Tomography, X-Ray Computed

Two commonly used tumor-seeking agents for PET are 2-deoxy-2-18F-fluoro-D-glucose (FDG) and L-methyl-11C-methionine (Met). This study compared FDG and Met in detecting residual or recurrent malignant tumors in the same patients.. Thirty-four lesions in 24 patients with clinically suspected recurrent or residual tumors were studied with PET using Met as well as FDG. FDG scans were conducted 1 hr after the completion of PET with Met. The color-coded superimposed images of standardized uptake values (SUVs) and transmission data were produced, and the peak SUVs in the lesions were then evaluated. Lesions above 2.5 SUV were interpreted as positive results for active tumor.. The sensitivity of FDG-PET and Met-PET were 64.5% (20/31 lesions) and 61.3% (19/31 lesions), respectively. The mean SUV of FDG in residual or recurrent malignant tumors (n = 31) was significantly higher than that of Met but there was a significant correlation (r = 0.788, p < 0.01) between FDG and Met SUVs in all lesions (n = 34).. PET using FDG and Met appear equally effective in detecting residual or recurrent malignant tumors although FDG uptakes were slightly higher than Met uptakes. Both showed a limited diagnostic sensitivity for small (< 1.5 cm) tumors.

Topics: Adult; Aged; Bone Neoplasms; Breast Neoplasms; Deoxyglucose; Female; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Humans; Lung Neoplasms; Male; Methionine; Middle Aged; Neoplasm Recurrence, Local; Neoplasm, Residual; Sensitivity and Specificity; Soft Tissue Neoplasms; Tomography, Emission-Computed

The purpose of the study was to assess the feasibility of PET and L-[methyl-11C]methionine (11C-methionine) in the detection of malignant melanoma.. Ten patients diagnosed with malignant melanoma (two with primary melanoma and eight with metastatic melanoma of the skin) but had no liver metastases underwent a PET study before starting cancer therapy. Dynamic scanning was performed for 40 min in seven patients and 10-20 min in three patients 25-45 min postinjection.. Carbon-11-methionine PET detected all melanoma lesions greater than 1.5 cm (n = 22) in diameter, whereas five smaller pulmonary lesions were not detected. The average standardized uptake value of the untreated lesions was 6.3 +/- 2.1 (n = 19) and the uptake rate (influx constant) was 0.085 +/- 0.041 min-1 (n = 16).. PET imaging with 11C-methionine is an effective method for visualizing melanoma. It may also be useful in measuring tumor metabolic activity in vivo.

Topics: Adult; Aged; Aged, 80 and over; Ear Neoplasms; Ear, External; Feasibility Studies; Female; Humans; Lung Neoplasms; Lymphatic Metastasis; Male; Melanoma; Methionine; Middle Aged; Nasal Cavity; Nose Neoplasms; Skin Neoplasms; Tomography, Emission-Computed