[ 18 F]Fluoro-2-deoxy-2- d -glucose versus 3′-deoxy-3′-[ 18 F]fluorothymidine for defining hematopoietically active pelvic bone marrow in gynecologic patients

Abstract

Background and Purpose We compared [18F]fluoro-2-deoxy-2-D-glucose (FDG) versus 3′-deoxy-3′-[18F]fluorothymidine (FLT) for the purpose of identifying active pelvic bone marrow (BM), quantifying its locational variation, and determining which technique is likely to be better for BM-sparing radiation planning. Material and Methods We sampled 41 patients, of which 25 underwent FDG-PET/CT only, 7 underwent FLT-PET/CT only, and 9 underwent both. Active BM subvolumes were defined as subsets of the pelvic BM with the highest standardized uptake values comprising 40%, 50%, and 60% of the total pelvic BM volume. We used the Dice similarity coefficient to quantify the percent overlap of active BM volumes of equal size. Differences in the spatial distribution of active BM were assessed using a region-growing algorithm. Results For patients with both modalities, the mean Dice coefficients for the 40%, 50%, and 60% subvolumes were 0.683, 0.732, and 0.781 respectively. Comparing individual active BM subvolumes to the mean subvolume, Dice coefficients varied from 0.598–0.889 for FDG and 0.739–0.912 for FLT. Region growing analysis showed FLT-PET defined more highly clustered active BM subvolumes. Conclusions Within the limitations of a small sample size, we found significant agreement between FDG-PET and FLT-PET; however, FLT-PET had significantly less individual variation and is likely to be superior to FDG-PET for BM-sparing radiotherapy.

Longitudinal Changes in Active Bone Marrow for Cervical Cancer Patients Treated With Concurrent Chemoradiation Therapy

“…On the whole, our findings indicate that variation in compensatory response after CRT could explain the increased HT seen with more intensive chemotherapy, resulting from impaired recovery of hematopoiesis in unirradiated structures. Many imaging modalities have been used to identify regions of functional (active) BM, including 18 F-FDG-PET, 18 F-FLT-PET, and magnetic resonance imaging (MRI) (16,(19)(20)(21)(22)(23)(24)(25). In 1 study, Elicin et al (19) used 18 F-FDG-PET imaging of pelvic BM to identify hematopoietically ABM and found that relatively low doses of radiation were associated with a reduction in SUV, which was correlated Abbreviations: ABM Z active bone marrow; CI Z confidence interval.…”

“…In another study, Yagi et al (20) showed regional functional heterogeneity of BM site-dependent response to treatment using longitudinal 18 F-FDG-PET imaging data. Thus, 18 F-FDG-PET imaging appears to be a valid imaging method for localizing functional BM, although recent studies suggest that 18 F-FLT-PET could be better for this purpose (21). In pelvic malignancies, intensive chemotherapy regimens have been associated with increased rates of acute HT.…”

“…Furthermore, sparing ABM using intensity modulated RT (IMRT) may be an effective strategy to reduce HT (16,17). Various functional imaging modalities have been used to identify ABM, such as 2-deoxy-2-[fluorine-18]fluoro-D-glucose ( 18 F-FDG) and 3 0 -deoxy-3 0 -[18F] fluorothymidine ( 18 F-FLT) positron emission tomography (PET) (18)(19)(20)(21). These studies suggest that BM-sparing IMRT may improve tolerance to chemotherapy in the concurrent and potentially the adjuvant and salvage settings.…”

Feasibility of atlas-based active bone marrow sparing intensity modulated radiation therapy for cervical cancer

“…Functional imaging using [ Although studies have found that incorporating functional imaging with IMRT planning is likely to be effective [15][16][17][18][19], this approach remains investigational. Moreover, functional imaging is expensive and not universally available.…”

“…where NðA \ BÞ is the number of elements that intersect between set A and set B, NðAÞ is the number of elements in set A, and NðBÞ is the number of element in set B [19]. Note that the Dice coefficient is meaningful when the two volumes have approximately similar size.…”