Claudio Landoni

C-11 choline versus F-18 fluorodeoxyglucose for imaging meningiomas: an initial experience.

Purpose: Positron emission tomography/computed tomography (PET/CT) with C-11 choline has been used for staging, restaging, and follow-up of various tumors, whereas its role for imaging meningiomas has only been preliminarily explored. The aim of this study was to compare C-11 choline and F-18 fluorodeoxyglucose (F-18 FDG) uptake in meningiomas and relate these findings to the histopathological analysis. Methods: Two sequential three-dimensional PET/CT scans with 370 MBq (10 mCi) of C-11 choline and 370 MBq (10 mCi) of F-18 FDG were performed 2 hours apart in 7 patients with histologically confirmed meningiomas. Five patients had WHO grade I and 2 had WHO grade II meningioma. For each scan, two-dimensional regions of interest were drawn on tumor boundaries and on the contralateral side on CT images and copied to the corresponding PET images. SUVmax and tumor-to-background ratio were calculated. Results: Relative to the contralateral side, C-11 choline uptake was increased in all meningiomas, whereas F-18 FDG uptake was decreased in 6 patients and increased in 1 of the 2 patients with grade II meningiomas. In the whole group, SUVmax of C-11 choline and F-18 FDG were 3.6 ± 1.3 and 5.7 ± 1.3, respectively. The tumor-to-background ratio for C-11 choline was much higher than that for F-18 FDG (5.3 ± 0.8 vs. 0.9 ± 0.2, respectively) (P < 0.001). The uptake of C-11 choline was higher in patients with grade II than in grade I meningiomas. Conclusions: These preliminary results suggest that C-11 choline may better image meningiomas in comparison with F-18 FDG. Clinical applications of C-11 choline PET/CT for grading and follow-up of meningiomas need to be assessed in further studies.

MRI, antibody-guided scintigraphy, and glucose metabolism in uveal melanoma.

To evaluate the usefulness of structural and biochemical imaging techniques for the diagnosis of uveal melanoma, 12 patients with choroidal melanoma were examined. Magnetic resonance imaging was used in 11 of 12 patients, as one had a metal prosthesis. All the subjects underwent single photon planar scintigraphy (SPPS) and single photon emission computed tomography (SPECT) using the 99mTc-labeled F(ab)2 of the anti-melanoma monoclonal antibody 225.28S ([99mTc]MoAb) and positron emission tomography (PET) using [18F]fluorodeoxyglucose ([18F]FDG). Magnetic resonance identified 6 of 11 melanotic lesions (definite melanomas) and 4 of 11 hypomelanotic lesions (probable melanomas), whereas in one case it was inconclusive. [99mTc]MoAb uptake was observed in 5 of 12 lesions using SPPS and 8 of 12 lesions using SPECT. [18F]FDG uptake was observed in 3 of 12 lesions by PET. These results demonstrate that both MR and radioimmunoscintigraphy are sensitive techniques for the diagnosis of choroidal melanomas and suggest that the detection of melanomas by MR, SPPS, and SPECT is largely dependent upon their size. The validity of these conclusions was verified in four subjects in whom the diagnosis was based on MR and/or SPECT findings only and confirmed by histology. The finding that only some of the uveal melanomas of larger size are visualized based on [18F]FDG uptake suggests that melanomas can have either high or low glucose consumption.

The Role of Imaging in the Diagnosis and Staging of Primary and Recurrent Rectal Cancer

Malignant tumors of the rectum are most commonly detected by fecal occult blood testing, digital rectal examination, barium enema or lower gastrointestinal endoscopy (rigid sigmoidoscopy, flexible sigmoidoscopy or colonoscopy). The decision regarding appropriate treatment in the patient with rectal cancer depends on accurate imaging of the tumor in an effort to define tumor depth, the presence of involved mesorectal nodal involvement, and any evidence of distant metastases at the time of initial diagnosis. In the former instance, delineation of confinement of the tumor to the mucosa or submucosa would enhance decision making regarding local therapies such as local excision of distal lesions, trans anal endomicrosurgery of small, more proximal tumors, photocoagulation or contact irradiation.

Increased [11C]Choline Uptake in Bronchioloalveolar Cell Carcinoma with Negative [18F]FDG Uptake. A PET/CT and Pathology Study

A case of a patient with bronchioloalveolar cell predominate lung adenocarcinoma (BAC) studied using integrated Positron Emission Tomography and Computed Tomography (PET/CT) with both 18F-fluorodeoxyglucose ([18F]FDG-PET) and [11C]Choline ([11C]Choline-PET) is described, with the aim of evaluating a new non invasive imaging method to detect and stage BAC, and providing information on tumour biology in vivo. The information derived from combining the two tracers could help in distinguishing lung adenocarcinoma with large BAC components ([18F]FDG negative and [11C]Choline positive) from inflammatory lesion ([18F]FDG and [11C]Choline positive). In addition, the simultaneous use of two PET tracers, evaluating two different metabolic pathways, together with histopathologic, immunohistochemical and gene expression analysis, could help to improve understanding of tumour in vivo behaviour.