Determination of an Optimal Standardized Uptake Value of Fluorodeoxyglucose for Positron Emission Tomography Imaging to Assess Pathological Volumes of Cervical Cancer: A Prospective Study

Abstract

PurposeTo determine the optimal standardized uptake value (SUV) of 18F-fluorodeoxyglucose (18F-FDG) for positron emission tomography (PET) imaging, at which the PET-defined gross tumor volume (GTVPET) best matches with the pathological volume (GTVPATH) in the cervical cancer.Materials and MethodsTen patients with the cervical cancer who underwent surgery were enrolled in this study. The excised specimens were processed for whole-mount serial sections and H-E staining. The tumor borders were outlined in sections under a microscope, histopathological images were scanned and the GTVPATH calculated. The GTVPET was delineated automatically by using various percentages relative to the maximal SUV and absolute SUV. The optimal threshold SUV was further obtained as the value at which the GTVPET best matched with the GTVPATH.ResultsAn average of 85±10% shrinkage of tissue was observed after the formalin fixation. The GTVPATH was 13.38±2.80 cm3 on average. The optimal threshold on percentile SUV and absolute SUV were 40.50%±3.16% and 7.45±1.10, respectively. The correlation analysis showed that the optimal percentile SUV threshold was inversely correlated with GTVPATH (p<0.05) and tumor diameter (p<0.05). The absolute SUV was also positively correlated with SUVmax (p<0.05).ConclusionThe pathological volume could provide the more accurate tumor volume. The optimal SUV of FDG for PET imaging by use of GTVPATH as standard for cervical cancer target volume delineation was thus determined in this study, and more cases are being evaluated to substantiate this conclusion.

Pathology-validated PET image data sets and their role in PET segmentation

“…Also, most of the studies considered only GTV path [25,33,34,38,56], but a few also evaluated the PET-derived GTV against both the GTV path and the CTV path [27,28]. While the additional comparison with the CTV path further complicates the investigation, it is very valuable in providing the CTV tumor margin, which in addition to being disease-and location-dependent may also be anisotropic.…”

“…These studies have common steps that are discussed below by tumor location: specimen fixation (for all except one), registration of the specimen with the images, and deformation corrections for some of them (Table 2). Such are the PSPVs generated by Daisne et al [25], Caldas-Magalhaes et al [26], Stroom et al [27], Van Loon et al [28], Yu et al [29], Meng et al [30], Schaefer et al [31], Dahele et al [32], Wanet et al [33], Zhang et al [34], and Roels et al [35]. After this, we provide an overview of the volumetric studies.…”

“…Threshold [27-29, 33, 43] Adaptive threshold [12,31,33,52] Gradient [47] Fuzzy C-means [48] Active contours [49] FLAB [54] Neural network [55] Multimodality using level sets [51] Cervical cancer Threshold [34] Colon, rectal and sigmoid cancer Threshold [39,45] Adaptive threshold [35,44] Gradient [35,39] multimodality segmentation tool using level sets and Jensen-Renyi divergence (JRD). They compared the results to those from Zaidi et al [50], and found that the JRD approach was second to the FCM-SW method.…”

“…Pathology processing Zhang et al [34] aimed at determining the optimal SUV cutoff for FDG PET scans of patients with cervical cancer by matching the volume measured on the extracted specimen to GTV PET . The pathology procedure includes fixing the extracted specimen with a 10 % formalin solution, cutting it into serial slices of 4 mm thickness and embedding them in paraffin.…”

“…Cervical cancer Zhang et al [34] searched for optimal segmentation thresholds and found that for their 10 cervical cancer patients the optimal percent and absolute SUV thresholds were 40.50 ± 3.16 % and 7.45 ± 1.10, respectively. They also found that the optimal percent SUV threshold was inversely correlated with GTV path and tumor diameter and that the SUV threshold was positively correlated with SUV max.…”