carbon-11-methionine and Breast-Neoplasms

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

Breast cancer is one of the principal oncological challenges in the Western world. Currently, there are only a few reliable predictive methods for monitoring treatment. We investigated the ability of carbon-11 methionine ("11C-MET) positron emission tomography (PET) to evaluate early response to therapy in advanced breast cancer.. Thirteen patients with metastases in the lungs/pleura, lymph nodes, soft tissue, or bones entered a MET PET study both before and after the first cycle of polychemotherapy (n=4), or after the first month of therapy with hormones (n=5), or low dose weekly cytostatics (n=3). One patient underwent three PET studies: before hormonal therapy, after 1 month of hormonal therapy, and after the first cycle of polychemotherapy (total, 27 studies). MET accumulation in the metastatic sites was measured as standardized uptake values (SUVs), and the pretreatment and post-treatment SUVs were compared with each other and the clinical follow-up data.. A total of 26 different metastatic sites were investigated in 13 patients. All metastases were visible by MET PET except one superficially spreading local skin recurrence, probably because of respiratory movements. Five new metastatic sites were detected. After therapy the SUVs decreased significantly (30-54%; P < 0.05) in all six responding metastatic sites, whereas the SUVs of nonresponding metastases decreased somewhat (11-130/%; n=4), remained stable (+/- 8%; n=10), or increased (13-23%; n=4) (P=NS). The SUVs of two nonresponding metastatic sites decreased clearly. Physiological MET uptake in the salivary glands, the myocardium, and the bone marrow did not disturb the image interpretation.. MET PET may be useful in assessing the early response to therapy in advanced breast cancer.

Topics: Adult; Aged; Bone Neoplasms; Breast Neoplasms; Female; Humans; Male; Methionine; Middle Aged; Positron-Emission Tomography; Soft Tissue Neoplasms; Treatment Outcome

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