Multicenter Reproducibility of 18F-Fluciclatide PET Imaging in Subjects with Solid Tumors.

UNLABELLED: Integrins are upregulated on both tumor cells and associated vasculature, where they play an important role in angiogenesis and metastasis. Fluciclatide is an arginine-glycine-aspartic acid peptide with high affinity for αvß3/αvß5 integrin, which can be radiolabeled for PET imaging of angiogenesis. Thus, (18)F-fluciclatide is a potential biomarker of therapeutic response to antiangiogenic inhibitors. The aim of this study was to evaluate the reproducibility of (18)F-fluciclatide in multiple solid-tumor types. METHODS: Thirty-nine patients underwent PET/CT scanning at 40, 65, and 90 min after injection of (18)F-fluciclatide (maximum, 370 MBq) on 2 separate days (2-9 d apart). Patients did not receive any therapy between PET/CT scans. (18)F-fluciclatide images were reported and quantitative measures of uptake were extracted using the PERCIST methodology. Intrasubject reproducibility of PET uptake in all measurable lesions was evaluated by calculating relative differences in SUV between PET scans for each lesion during the 2 imaging sessions. RESULTS: Thirty-nine measurable lesions were detected in 26 patients. Lesion uptake correlated strongly across imaging sessions (r = 0.92, P < 0.05, at 40 min; r = 0.94, P < 0.05, at 65 min; r = 0.94, P < 0.05, at 90 min) with a mean relative difference and SD of the relative difference of 0.006 ± 0.18 at 40 min, 0.003 ± 0.19 at 65 min, and 0.025 ± 0.20 at 90 min. This reflects 95% limits of repeatability of 35%-39% for the difference between the 2 SUV measurements or a variability of 18%-20% in agreement from that observed in well-calibrated multicenter (18)F-FDG studies. CONCLUSION: The test-retest reproducibility of (18)F-fluciclatide across multiple tumor types has been measured and shown to be acceptable. This is an important step in the development of this in vivo biomarker to identify and quantify response to antiangiogenic therapy in cancer patients.

Preparation of patient doses of (177)Lu-DOTA-TATE using indigenously produced (177)Lu: the Indian experience.

PURPOSE: (177)Lu (T(1/2) = 6.73 days, E(ß(max)) = 0.497 MeV, E(γ) = 113 KeV [6.4%] and 208 KeV [11%])-labeled DOTA-TATE, a somatostatin analog, is presently being considered a promising agent for the treatment of patients suffering from inoperable neuroendocrine tumors, which overexpress somatostatin receptors. The objective of the present work was to develop an optimized protocol for the preparation of therapeutic dose of (177)Lu-DOTA-TATE with as high as achievable specific activity at the time of its administration, taking into account the variable specific activity of (177)Lu available during the preparation of the agent. METHODS: (177)Lu labeling of DOTA-TATE was carried out using a precalculated amount of DOTA-TATE based on the available specific activity of (177)Lu at the time of preparation, keeping a minimum molar ratio of [DOTA-TATE]:[Lu] = 4:1, so that (177)Lu-DOTA-TATE could be obtained with highest possible specific activity without compromising its radiochemical purity and stability. RESULTS: One hundred (100) batches of (177)Lu-DOTA-TATE were prepared following this protocol till date at five different nuclear medicine centers of India, with a radiochemical purity of 98.25% ± 1.1% and specific activity of 32.74-65.49 GBq/µmol (885-1770 mCi/µmol). Till date, 250 patient doses of (177)Lu-DOTA-TATE have been dispensed and administered in 150 patients suffering from various types of neuroendocrine-originated tumors. CONCLUSIONS: The developed method ensures that patient doses of (177)Lu-DOTA-TATE could be prepared with highest possible specific activity depending upon the available specific activity of (177)Lu at the hospital radio-pharmacy.

Marchiafava-Bignami disease: Two cases with magnetic resonance imaging and positron emission tomography scan findings.

We report two patients with Marchiafava-Bignami disease (MBD). A 38-year-old male with chronic alcohol abuse developed acute onset cerebellar ataxia and altered sensorium. He was diagnosed to have acute form (Type II) of MBD. Magnetic resonance imaging (MRI) showed extensive lesions involving the corpus callosum in its entire extent and also bilateral corona radiata and centrum semiovale. Corpus callosum had heterogeneous signal changes with ring enhancement. Positron emission tomography scan demonstrated reduced cerebral glucose metabolism diffusely over both the cerebral hemispheres. The second patient was 55-year-old male with chronic alcohol intake developed acute onset vomiting followed by behavioral abnormalities and altered sensorium. MRI showed diffuse lesion involving entire corpus callosum with suggestion of necrosis. Both the patients subsequently recovered, the first patient is back to his previous occupation and the second patient could be rehabilitated with some lighter work in his previous work place. Functional brain imaging may help to understand the pathogenesis of acute MBD and possibly the behavioral manifestations.

PET/CT-guided percutaneous biopsy of isolated intramuscular metastases from postcricoid cancer.

(18)F-FDG PET/CT has made it possible to identify many unsuspected lesions such as isolated intramuscular metastases because of its ability to detect abnormal metabolic activity in an early stage even without clinical symptoms or morphologic changes. We need to modify our routine techniques for performing biopsies of such lesions because they may not be visualized on morphologic imaging. We describe a technique in which fused PET/CT is used to guide the percutaneous biopsy needle for sampling isolated intramuscular metastatic lesions in a patient whose intramuscular metastases were identified only on PET/CT, not on CT or ultrasound, and were clinically occult.