Clinical and Prognostic Value of PET/CT Imaging with Combination of 68Ga-DOTATATE and 18F-FDG in Gastroenteropancreatic Neuroendocrine Neoplasms

Abstract

Background: To evaluate the clinical and prognostic value of PET/CT with combination of ⁶⁸Ga-DOTATATE and ¹⁸F-FDG in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs).

Method: 83 patients of GEP-NENs who underwent ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT were enrolled between June 2013 and December 2016. Well-differentiated (WD) NETs are divided into group A (Ki-67 < 10%) and group B (Ki-67 ≥ 10%), and poorly differentiated (PD) NECs are defined as group C. The relationship between PET/CT results and clinicopathological characteristics was retrospectively investigated.

Result: For groups A/B/C, the sensitivities of ⁶⁸Ga-DOTATATE and ¹⁸F-FDG were 78.8%/83.3%/37.5% and 52.0%/72.2%/100.0%. A negative correlation between Ki-67 and SUV_max of ⁶⁸Ga-DOTATATE (R = -0.415; P ≤ 0.001) was observed, while a positive correlation was noted between Ki-67 and SUV_max of ¹⁸F-FDG (R = 0.683; P ≤ 0.001). 62.5% (5/8) of patients showed significantly more lesions in the bone if ⁶⁸Ga-DOTATATE was used, and 22.7% (5/22) of patients showed more lymph node metastases if ¹⁸F-FDG was used.

Conclusions: The sensitivity of dual tracers was correlated with cell differentiation, and a correlation between Ki-67 and both SUV_max of PET-CTs could be observed. ⁶⁸Ga-DOTATATE is suggested for WD-NET and ¹⁸F-FDG is probably suitable for patients with Ki-67 ≥ 10%.

Figure 1

Comparison of SUV_max of PET/CT according to primary sites ((a) and (b)) and tumor grade ((c) and (d)). The sensitivity of group A (G1 + G2a = Ki-67 < 10%), group B (G2b + G3a = well-differentiated neoplasms with Ki-67 ≥ 10%), and group C (G3b = poorly differentiated neoplasms with Ki-67 > 20%) in PET/CT imaging.

Figure 2

A 37-year-old women with pancreatic NEC G3 (Ki-67 = 80%) and lymph node, liver, and bone metastases, from whom the primary lesion has been resected. ¹⁸F-FDG PET/CT showed more liver lesions, while ⁶⁸Ga-DOTATATE detected more bone lesions. ((A) and (a)) Liver lesions showed heterogeneity in SSTR expression. ((B) and (b) and (C) and (c)) ¹⁸F-FDG PET/CT failed to show bone metastases in rib and lumbar vertebra.

Figure 3

The overall survival of unresectable patients detected with dual tracers: (a) Kaplan-Meier survival curve for unresectable patients, (A) positive for both tracers, (B) ⁶⁸Ga-DOTA-TATE only, and (C) ¹⁸F-FDG only; (b) unresectable NET patients with ⁶⁸Ga-DOTA-TATE results (positive or negative); (c) unresectable NET patients with ¹⁸F-FDG results (positive or negative); (d) unresectable NEC patients with ⁶⁸Ga-DOTA-TATE results (positive or negative).

Figure 4

PET/CT imaging and treatment regime.