Twins in spirit part II: DOTATATE and high-affinity DOTATATE-the clinical experience

Purpose Over recent decades interest in diagnosis and treatment of neuroendocrine tumours (NET) has steadily grown. The basis for diagnosis and therapy of NET with radiolabelled somatostatin (hsst) analogues is the variable overexpression of hsst receptors (hsst1-5 receptors). We hypothesized that radiometal derivatives of DOTA-iodo-Tyr(3)-octreotide analogues might be excellent candidates for somatostatin receptor imaging. We therefore explored the diagnostic potential of Ga-68-DOTA-iodo-Tyr(3)-octreotate [Ga-68-DOTA,3-iodo-Tyr(3),Thr(8)]octreotide (Ga-68-HA-DOTATATE; HA, high-affinity) compared to the established Ga-68-DOTA-Tyr(3)-octreotate (Ga-68-DOTATATE) in vivo. Methods The study included 23 patients with known somatostatin receptor-positive metastases from NETs, thyroid cancer or glomus tumours who were investigated with both Ga-68-HA-DOTATATE and Ga-68-DOTATATE. A patient-based and a lesion-based comparative analysis was carried out of normal tissue distribution and lesion detectability in a qualitative and a semiquantitative manner. Results Ga-68-HA-DOTATATE and Ga-68-DOTATATE showed comparable uptake in the liver (SUVmean 8.9 +/- 2.2 vs. 9.3 +/- 2.5, n.s.), renal cortex (SUVmean 13.3 +/- 3.9 vs. 14.5 +/- 3.7, n.s.) and spleen (SUVmean 24.0 +/- 6.7 vs. 22.9 +/- 7.3, n.s.). A somewhat higher pituitary uptake was found with Ga-68-HA-DOTATATE (SUVmean 6.3 +/- 1.8 vs. 5.4 +/- 2.1, p < 0.05). On a lesion-by-lesion basis a total of 344 lesions were detected. Ga-68-HA-DOTATATE demonstrated 328 lesions (95.3 % of total lesions seen), and Ga-68-DOTATATE demonstrated 332 lesions (96.4 %). The mean SUVmax of all lesions was not significantly different between Ga-68-HA-DOTATATE and Ga-68-DOTATATE (17.8 +/- 11.4 vs. 16.7 +/- 10.7, n.s.). Conclusion Our analysis demonstrated very good concordance between Ga-68-HA-DOTATATE and Ga-68-DOTATATE PET data. As the availability and use of Ga-68-HA-DOTATATE is not governed by patent restrictions it may be an attractive alternative to other Ga-68-labelled hsst analogues.