title: Gastroenteropancreatic neuroendocrine tumors: standardizing therapy monitoring with 68Ga-DOTATOC PET/CT using the example of somatostatin receptor radionuclide therapy.
abstract: The purpose of this study was to standardize therapy monitoring of hepatic metastases from gastroenteropancreatic neuroendocrine tumors (GEP-NETs) during the course of somatostatin receptor radionuclide therapy (SRRT). In 21 consecutive patients with nonresectable hepatic metastases of GEP-NETs, chromogranin A (CgA) and 68Ga-DOTATOC PET/CT were compared before and after the last SRRT. On 68Ga-DOTATOC PET/CT, the maximum standard uptake values (SUVmax) of normal liver and hepatic metastases were calculated. In addition, the volumes of hepatic metastases (volume of interest [VOI]) were measured using four cut-offs to separate normal liver tissue from metastases (SUVmax of the normal liver plus 10% [VOIliver+10%], 20% [VOIliver+20%], 30% [VOIliver+30%] and SUV  =  10 [VOI10SUV]). The SUVmax of the normal liver was below 10 (7.2 ± 1.3) in all patients and without significant changes. Overall therapy changes (Δ) per patient (mean [95% CI]) were statistically significant with p < .01 for ΔCgA  =  -43 (-69 to -17), ΔSUVmax  =  -22 (-29 to-14), and ΔVOI10SUV  =  -53 (-68 to -38)% and significant with p < .05 for ΔVOIliver+10%  =  -29 (-55 to -3)%, ΔVOIliver+20%  =  -32 (-62 to -2) and ΔVOIliver+30%  =  -37 (-66 to -8). Correlations were found only between ΔCgA and ΔVOI10SUV (r  =  .595; p < .01), ΔSUVmax and ΔVOI10SUV (0.629, p < .01), and SUVmax and ΔSUVmax (r  =  -.446; p < .05). 68Ga-DOTATOC PET/CT allows volumetric therapy monitoring via an SUV-based cut-off separating hepatic metastases from normal liver tissue (10 SUV recommended).
authors.affiliation: Multiorgan Screening Foundation, and Department of Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, Frankfurt, Germany. luboldt@screening.org
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Luboldt
authors.forename: Holger
authors.initials: H
authors.lastname: Hartmann
authors.forename: Bärbel
authors.initials: B
authors.lastname: Wiedemann
authors.forename: Klaus
authors.initials: K
authors.lastname: Zöphel
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Luboldt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging*; D015282:Octreotide / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D017481:Receptors, Somatostatin / Q000627:therapeutic use*; D012015:Reference Standards; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; D017481:Receptors, Somatostatin; D015282:Octreotide; C106246:Edotreotide