Quantitative SPECT/CT Imaging of 177Lu with In Vivo Validation in Patients Undergoing Peptide Receptor Radionuclide Therapy
| Autor: | Joachim Hornegger, Philipp Ritt, James C. Sanders, Torsten Kuwert |
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| Rok vydání: | 2014 |
| Předmět: |
Adult
Male Cancer Research Mean squared error Urinary Bladder Digestive System Neoplasms Octreotide Imaging phantom In vivo Organometallic Compounds Calibration Humans Dosimetry Medicine Radiology Nuclear Medicine and imaging Aged Aged 80 and over Tomography Emission-Computed Single-Photon Phantoms Imaging business.industry Middle Aged Confidence interval Neuroendocrine Tumors Oncology Radionuclide therapy Female Tomography Tomography X-Ray Computed Nuclear medicine business Algorithms |
| Zdroj: | Molecular Imaging and Biology. 17:585-593 |
| ISSN: | 1860-2002 1536-1632 |
| Popis: | Purpose: The purpose of this study is to extend an established SPECT/CT quantitation protocol to 177 Lu and validate it in vivo using urine samples, thus providing a basis for 3D dosimetry of 177 Lu radiotherapy and improvement over current planar methods which improperly account for anatomical variations, attenuation, and overlapping organs. Procedures: In our quantitation protocol, counts in images reconstructed using an ordered subsetexpectation maximization algorithm are converted to kilobecquerels per milliliter using a calibration factor derived from a phantom experiment. While varying reconstruction parameters, we tracked the ratio of image to true activity concentration (recovery coefficient, RC) in hot spheres and a noise measure in a homogeneous region. The optimal parameter set was selected as the point where recovery in the largest three spheres (16, 8, and 4 ml)stagnated, while the noise continued to increase. Urine samples were collected following 12 SPECT/CT acquisitions of patients undergoing [ 177 Lu]DOTATATE therapy, and activity concentrations were measured in a well counter. Data was reconstructed using parameters chosen in the phantom experiment, and estimated activity concentration from the images was compared to the urine values to derive RCs. Results: In phantom data, our chosen parameter set yielded RCs in 16, 8, and 4 ml spheres of 80.0, 74.1, and 64.5 %, respectively. For patients, the mean bladder RC was 96.1±13.2 % (range, 80.6–122.4 %), with a 95 % confidence interval between 88.6 and 103.6 %. The mean error of SPECT/CT concentrations was 10.1±8.3 % (range, �19.4–22.4 %). Conclusions: Our results show that quantitative 177 Lu SPECT/CT in vivo is feasible but could benefit from improved reconstruction methods. Quantifying bladder activity is analogous to determining the amount of activity in the kidneys, an important task in dosimetry, and our results provide a useful benchmark for future efforts. |
| Databáze: | OpenAIRE |
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