Standardized uptake values and ratios on 68Ga-DOTATATE PET-computed tomography for normal organs and malignant lesions and their correlation with Krenning score in patients with metastatic neuroendocrine tumors

Abstract

The aim was to estimate the physiological standardized uptake values (SUVs) on 68Ga-DOTATATE PET-computed tomography (CT) in normal organs and metastatic tumor lesions (both standard and delayed), and correlating the uptake values and ratios with Krenning Scores (K-score) in patients with metastatic/advanced neuroendocrine tumors (NETs) undergoing PET-CT studies for their management work-up. A total of 32 patients of metastatic NET with 95 discrete tumor lesions were included in this analysis. These patients underwent standard whole-body PET-CT following injection of 2–3 mCi (74–111 MBq) of 68Ga-DOTATATE at 1–1.5 h. The normal physiological SUVmean of the liver and spleen and SUVmax and SUVmean of tumor lesions were estimated by an in-built automated procedure. These patients also underwent a delayed scan (2.5–3 h) and the same parameters were obtained for the delayed study. The tumorous lesions were further classified on the basis of K-score, and this was correlated with the mean SUVmax on both early and delayed scans. SUVmean ratios (tumor-to-liver and tumor-to-spleen) were also calculated for both time-points and correlated with individual K-scores. In lesions with K-score 4, the mean SUVmax was 32.5 in early and 30.5 in delayed scan, for lesions with K-score of 3 and 2, the mean SUVmax were 17.3, 20, and 9.3, 9.2, respectively, while in K-score 1 (n = 1), the delayed mean SUVmax was found to be more than early mean SUVmax (3.2 to 2.3). Statistical significance was evaluated by paired t test, and the changes in SUVmax was found to be statistically insignificant (P > 0.05) in all 3 K-scores. The paired t test was also performed between early and delayed tumor/liver and tumor/spleen mean SUVmean ratios, and no significant changes were observed across all K scores. The mean SUVmean values of the liver in the standard 1-h scan and delayed scans were 8.05 (range: 3–15) and 8.17 (range: 3.2–16), while for spleen, the values were 18 (range: 8.4–36.7) and 20 (range: 10–38.6), respectively. Statistically significant changes were observed in delayed spleen SUVmean values compared to the early scan (P < 0.05), while for liver SUVmean, the difference was not significant. Thus, in the present study, the SUVmax and SUVmean (range and mean values) for normal liver and spleen, and malignant NET lesions, and tumor-to-liver and tumor-to-spleen SUVmean ratios of different K-scores were generated. As could be theoretically expected in receptor-based PET-CT, there was no significant change in the delayed scan compared to the standard 1–1.5 h values

Incidence, Clinical Presentation and Trends in Indication for Diagnostic Work-Up of Small Intestinal and Pancreatic Neuroendocrine Tumors

“…The histological diagnosis was based on immunohistochemical staining for synaptophysin and chromogranin-A (CgA) on surgically resected specimens or core biopsies. If a patient declined biopsy or it was not feasible to perform one, a diagnosis was established if a tumor was visible on either CT or MRI and SRI (with high tracer uptake, Krenning grade 3-4 [17,18]). The exclusion criterion included mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN).…”

PET Criteria by Cancer Type from Imaging Interpretation to Treatment Response Assessment: Beyond FDG PET Score

“…The predictive role of KS from [ 68 Ga]Ga-DOTA-NOC PET/CT was also demonstrated in lung carcinoids, with high sensitivity [ 40 ]. Finally, Menon and colleagues explored a dual-time-point [ 68 Ga]Ga-DOTA-TATE PET/CT imaging protocol, but no significant changes in KS were reported [ 41 ]. The KS was created starting from [ 111 In]Pentetreotide scintigraphy; therefore, reliable standards and criteria for SSTR PET are still lacking since many pitfalls can influence PET scans [ 52 , 53 , 54 , 55 , 56 ].…”

Prognostic Evaluation of Metastatic Castration Resistant Prostate Cancer and Neuroendocrine Prostate Cancer with [68Ga]Ga DOTATATE PET-CT

“…Summation of [ 68 Ga]Ga-DOTATATE uptake parameters from all indexed lesions per patient was also recorded. In addition, visual comparison of the most [ 68 Ga]Ga-DOTATATE avid lesions was performed as a simple way to stratify the degree of uptake similar to that performed with Krenning scoring for patients with non-prostatic neuroendocrine carcinoma [ 18 ]. [ 68 Ga]Ga-DOTATATE PET uptake was visually classified with the lesion either having: (A) Mild [ 68 Ga]Ga-DOTATATE uptake (less than liver); defined as [ 68 Ga]Ga-DOTATATE uptake ≥ blood pool or L3 marrow < average liver (SUVmean) ( Figure 1 ).…”