Safety and efficiency of 68Ga-DOTA-conjugated-peptides PET scan has also been demonstrated ( 14). Of note, a wide array of tumoral lesions express these receptors and can be visualized by 68Ga-DOTA-conjugated-peptides PET scan ( 10). By virtue of 68Ga-DOTA-conjugated-peptides PET, not only image quality is enhanced but also the duration of the imaging procedure and effective dose are reduced ( 10, 11). Superior sensitivity and better resolution provided by PET and high avidity of 68Ga-DOTA-conjugated-peptides to SSRs revolutionized NET imaging ( 11). However, low-quality images, higher cumulative dose, long imaging protocol, etc. Initial functional imaging with SSR-analogues was performed exploiting 111In-DTPA Pentetreotide, which remained the method of choice for more than two decades ( 2). However, SSR2 and SSR5 are expressed in 70-90% of NETs ( 12). Five subtypes of SSRs have been discovered in various body cells as well as tumoral lesions ( 10, 11). Somatostatin receptors (SSRs) are found on cell membranes in the majority of the NETs ( 2). Also, whole-body diffusion-weighted magnetic resonance Imaging (DW-MRI) without CM administration has been utilized for the evaluation of metastasis, despite the fact that the procedure is time-consuming and expensive ( 9). The morphological imaging such as multi-detector CT with contrast medium (CM) provides rapid imaging and dynamic evaluation of CM which improves image resolution and leads in the detection of small NET lesions ( 8).

Multitudes of morphological and functional imaging modalities, such as sonography, CT, MRI, and scintigraphy have been employed for staging, re-staging and evaluation of response to therapy ( 1, 4, 6). Liver, lymph nodes and bone are the main metastatic target organs ( 7). Although NETs are generally non-aggressive, the metastasis is a frequent finding ( 2).

Hence, NETs are commonly detected in advanced, inoperable, or metastatic status ( 4, 6). Signs and symptoms of excessive hormone secretion are not clearly present in all patients, leading to delayed diagnosis ( 2). The incidence has remarkably increased, recently ( 4, 5). Neuroendocrine tumors (NETs) are rare slow-growing malignancies ( 1, 2) originating from the hormone-producing neuroendocrine system ( 3). In addition, comparing with 99mTc-Octreotide SPECT/CT and CT/MRI, 68Ga-DOTATATE PET/CT revealed more data in 44% and 36% of the patients, resulting in management modification in 24% and 20%, respectively. On lesion-based analysis, 68Ga-DOTATATE PET/CT found more organs (=0.02) and lesions (=0.001) in comparison with 99mTc-Octreotide SPECT/CT and also more lesions in comparison with CT/MRI (=0.003). The correlation between 68Ga-DOTATATE PET/CT and 99mTc-Octreotide SPECT/CT results was significant (=0.02 kappa value=0.57), no correlation, however, was depicted with CI (=0.07 kappa value=0.35). Also, the specificity was 80%, 80% and 75% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively.

On patient-based analysis, the sensitivity was 65%, 90% and 71% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. Overall, 77 lesions in 14 patients, 135 in 19 and 86 in 16 were detected on 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively.

Netspot neuroendocrine