Bone Marrow Absorbed Doses and Correlations with Hematologic Response During 177Lu-DOTATATE Treatments Are Influenced by Image-Based Dosimetry Method and Presence of Skeletal Metastases.

Abstract

This study aimed to compare different image-based methods for bone marrow dosimetry and study the dose-response relationship during treatment with 177Lu-DOTATATE in patients with and without skeletal metastases. Methods: This study included 46 patients with advanced neuroendocrine tumors treated with at least 2 fractions of 177Lu-DOTATATE at Sahlgrenska University Hospital. High- and low-uptake compartments were automatically outlined in planar images collected at 2, 24, 48, and 168 h after injection. The bone marrow absorbed doses were calculated from the cross doses of the high- and low-uptake compartments and the self-dose, using the time-activity concentration curve for the low-uptake compartment. This time-activity concentration curve was adjusted using a fixed constant of 1.8 for the planar dosimetry method and using the activity concentrations in vertebral bodies in SPECT images at 24 h after injection of 177Lu-DOTATATE in 4 hybrid methods: L4-SPECT used the activity concentration in the L4 vertebra, whereas V-SPECT, L-SPECT, and T-SPECT used the median activity concentration in all visible vertebrae, lumbar vertebrae, and thoracic vertebrae, respectively. Results: Using the planar method, L4-SPECT, V-SPECT, L-SPECT, and T-SPECT, the estimated median bone marrow absorbed doses were 0.19, 0.36, 0.40, 0.39, and 0.46 Gy/7.4 GBq, respectively, with respective ranges of 0.12-0.33, 0.15-1.44, 0.19-1.71, 0.21-1.60, and 0.18-2.12 Gy/7.4 GBq. For all methods, the bone marrow absorbed dose significantly correlated with decreased platelet counts. This correlation increased after treatment fraction 2: the Spearman correlation (rs) were -0.49 for the planar method, -0.61 for L4-SPECT, -0.63 for V-SPECT, -0.63 for L-SPECT, and -0.57 for T-SPECT. A separate analysis revealed an increased correlation for patients without skeletal metastases using the planar method (rs = -0.67). In contrast, hybrid methods had poor correlations for patients without metastases and stronger correlations for patients with skeletal metastases (rs = -0.61 to -0.74). The mean bone marrow absorbed doses were 3%-69% higher for patients with skeletal metastases than for patients without. Conclusion: The estimated bone marrow absorbed doses by image-based techniques and the correlation with platelets are influenced by the choice of measured vertebrae and the presence of skeletal metastases.

• Authors: Linn Hagmarker, Johanna Svensson, Tobias Rydén, Martijn van Essen, Anna Sundlöv, Katarina Sjögreen Gleisner, Peter Gjertsson, Peter Bernhardt
• Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine (J Nucl Med) Vol. 60 Issue 10 Pg. 1406-1413 (10 2019) ISSN: 1535-5667 [Electronic] United States
• PMID: 30902877 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2019 by the Society of Nuclear Medicine and Molecular Imaging.

Chemical References

• Organometallic Compounds
• Radiopharmaceuticals
• lutetium Lu 177 dotatate
• Octreotide

Topics

• Adult
• Aged
• Aged, 80 and over
• Bone Marrow (pathology, radiation effects)
• Bone Neoplasms (diagnostic imaging, secondary)
• Bone and Bones (diagnostic imaging, pathology)
• Female
• Humans
• Image Processing, Computer-Assisted
• Male
• Middle Aged
• Neoplasm Metastasis
• Neuroendocrine Tumors (diagnostic imaging, pathology)
• Octreotide (analogs & derivatives, pharmacology)
• Organometallic Compounds (pharmacology)
• Prospective Studies
• Radiometry
• Radiopharmaceuticals (pharmacology)
• Time Factors
• Tomography, Emission-Computed, Single-Photon
• Tomography, X-Ray Computed