68Ga-DOTATATE PET/CT, 99mTc-HYNIC-octreotide SPECT/CT, and whole-body MR imaging in detection of neuroendocrine tumors: A prospective trial

Abstract

Methods: Nineteen consecutive patients (34-77 y old; mean, 54.3 ± 10.4 y old; 10 men and 9 women) underwent SSRS SPECT/CT, 68Ga-DOTATATE PET/CT, and WB DWI. Images were acquired with a maximum interval of 3 mo between them and were analyzed with masking by separate teams. Planar whole-body imaging and SPECT/CT were performed from thorax to pelvis using a double-head 16-slice SPECT/CT scanner 4 h after injection of 111-185 MBq of 99mTc-HYNIC-octreotide. 68Ga-DOTATATE PET/CT was performed from head to feet using a 16-slice PET/CT scanner 45 min after injection of 185 MBq of tracer. WB DWI was performed in the coronal plane using a 1.5-T scanner and a body coil. The standard method of reference for evaluation of image performance was undertaken: consensus among investigators at the end of the study, clinical and imaging follow-up, and biopsy of suggestive lesions. There are different metabolic imaging methods, various tracers, and emerging anatomic modalities to stage neuroendocrine tumor (NET). We aimed to compare NET lesion detectability among 99mTc-hydrazinonicotinamide (HYNIC)-octreotide (somatostatin receptor scintigraphy [SSRS]) SPECT/CT, 68Ga-DOTATATE PET/CT, and whole-body diffusion-weighted MR imaging (WB DWI). Conclusion: 68Ga PET/CT seems to be more sensitive for detection of well-differentiated NET lesions, especially for bone and unknown primary lesions. NET can be staged with 68Ga-DOTATATE PET/CT. WB DWI is an efficient new method with high accuracy and without ionizing radiation exposure. SSRS SPECT/CT should be used only when 68Ga-DOTATATE PET/CT and WB DWI are not available. Results: McNemar testing was applied to evaluate the detectability of lesions using 68Ga-DOTATATE PET/CT in comparison to SSRS SPECT/CT and WB DWI: a significant difference in detectability was noted for pancreas (P = 0.0455 and P = 0.0455, respectively), gastrointestinal tract (P = 0.0455 and P = 0.0455), and bones (P = 0.0082 and P = 0.0082). Two unknown primary lesions were identified solely by 68Ga-DOTATATE PET/CT. 68Ga-DOTATATE PET/CT, SSRS SPECT/CT, and WB DWI demonstrated, respectively, sensitivities of 0.96, 0.60, and 0.72; specificities of 0.97, 0.99, and 1.00; positive predictive values of 0.94, 0.96, and 1.00; negative predictive values of 0.98, 0.83, and 0.88; and accuracies of 0.97, 0.86, and 0.91.