A Negative Correlation Between Blood Glucose Level and 68 Ga-DOTA-TOC Uptake in the Pancreas Uncinate Process

Determinants of the uptake of the uncinate process of pancreas in 68Ga-DOTATOC PET/CT: a retrospective study

PURPOSE

an increased uptake of the uncinate process of pancreas (UPP) has been described in about one-third of somatostatin receptor imaging procedures and may hinder image interpretation. The determinants of this uptake are however poorly understood. The aim of this study was to investigate the impact of cold somatostatin analogues (cSA) on UPP 68Ga-DOTATOC uptake. Age and diabetic status were also studied.

METHODS

all adult patients who performed a 68Ga-DOTATOC PET/CT in our center between May 2021 and April 2023 were retrospectively screened. For each one, UPP uptake was visually assessed and measured using SUVmax. Clinical data including cSA medication, age and diabetic status were collected. Univariate and multivariate analyses were conducted using logistic regression. SUVmax comparisons were conducted using a Mann-Whitney Wilcoxon test.

RESULTS

82 patients were included. UPP uptake was significantly lower in patients treated with cSA (OR 0.27, p = 0.015 in multivariate analysis), with a lower SUVmax (4.97 vs. 8.81, p = 0.001). No significant result was found regarding diabetic status or age.

CONCLUSION

cold somatostatin analog treatment decreased the physiological UPP uptake in 68Ga-DOTATOC PET/CT. This effect could be used to reduce interpretation errors in this location.

[68Ga]Ga-DOTANOC Uptake at Pancreatic Head/Uncinate Process: Is It a Persistent Diagnostic Pitfall Over Time?

Simple Summary

The purpose of the present study is to describe the frequency of non-malignant [68Ga]Ga-DOTANOC uncinate process (UP) uptake and to evaluate its variations over time. Among the first 6 months of enrolment of a monocentric prospective observational electronic archive, analyses of a large number of PET/CT scans (n = 268) of NEN pts (n = 172) demonstrated that: UP uptake is a frequent finding (observed in almost half of the cases, slightly higher than previously reported), mostly presenting with a diffuse pattern and, interestingly, characterized by variations over time in almost one third of the cases. The consciousness of this diagnostic pitfall is of utmost importance for accurate [68Ga]Ga-DOTANOC PET/CT reporting, since the pancreas represents one of the most frequent sites of NEN.

Abstract

Purpose: [68Ga]Ga-DOTA-peptide uptake in the pancreatic head/uncinate process (UP) is a frequent PET/CT finding. Although mostly physiologic, it can represent a pitfall in PET/CT reading, especially when focal. An increased frequency of UP uptake has been reported in patients (pts) affected by diabetes mellitus (DM). The aim of the study is to describe the frequency of [68Ga]Ga-DOTANOC UP uptake to evaluate its variations over time and its possible correlation with DM. Methods: In September 2017, a monocentric prospective observational electronic archive was initiated at our center to collect clinical and imaging data of pts undergoing [68Ga]Ga-DOTANOC PET/CT. Among the pts enrolled in the first 6 months (Sept 2017 to Feb 2018), those presenting [68Ga]Ga-DOTANOC PET/CT uptake at UP level were included. Pts with UP lesions already documented on CT/MRI or those that underwent surgical excision of UP before PET/CT were excluded from the analysis. [68Ga]Ga-DOTANOC UP uptake was classified as diffuse or focal and compared with the pattern observed in previous PET/CT scans performed at our center. An increased frequency of UP uptake was also correlated with the presence of DM. Results: In the first 6 months, 253 pts were enrolled in the archive and 172 out of them were included in the analysis. UP increased uptake was frequently observed (77/172, 44.8%) and was mostly diffuse (62/77). In 75/172 pts (43.6%), previous [68Ga]Ga-DOTANOC PET/CT scans were available (overall 268 scans; number of previous PET per pt range: 1–20) and were retrospectively reviewed. Despite the fact that, in most pts, the uptake pattern was stable over time (54/75 pts, 72%), it changed in approximately one third of cases (21/75, 28%). Among DM pts (29/172), only 10/29 (34.4%) presented increased UP uptake. Conclusions: UP [68Ga]Ga-DOTANOC uptake is a frequent non-malignant finding (slightly higher than previously reported), mostly presenting with a diffuse pattern. However, contrary to previous reports, our data show that the pattern of uptake may vary over time in approximately one third of the cases and it is not more frequently observed in pts with DM.