Abstract
Purpose: Exploring methods to improve diagnosis of neuroendocrine tumors (NET) in different locations using somatostatin receptors scintigraphy with 111In-octreotide. Material and methods: The study included 125 patients with NET in different locations. Activity of injected 111In-octreotide was 200–250 MBq (effective dose – 0.054 mSv/MBq), which allows to carry out a planar study as and single photon emission computed tomography. The study was performed after 24 hours on intravenous injection of indicator on the combined SPECT/CT machine Symbia T2 (Siemens, Germany). Results: In the sample of patients, NET distribution by localization is indicated in Fig. 1. The results of the study with 111In-octreotide are presented in the form of scintigrams in the whole body scanning mode and in the form of single-photon emission computer tomograms combined with CT. To determine the effectiveness of scintigraphy with 111In-octreotide, after a visual evaluation of the scintigrams obtained, the number of positive and negative results of the study was calculated. A comparison was made with the data of other methods and the number of TP, TN, FP, and FN results was determined. Further, the characteristic parameters of the method studied were calculated to determine its effectiveness. The study of values of characteristic parameters showed that the sensitivity was 73 % (95 % CI: 63–83 %), specificity – 97 % (95 % CI: 88–100 %) accuracy is 79 % (95 % CI: 71–87 %). The value of the positive predictive value of 99 % (95 % CI: 94–100 %), the predictive value of negative results – 55 % (95 % CI: 40–70 %). While the study shows a high frequency of TP results, while the frequencies of the TN and FN results are not significantly different (the average frequency of the FN results falls within the confidence interval for the frequency of the TN results). The method has a high value of the prognostic value of the positive result, which gives the right to assert about the high probability of the presence of a neuroendocrine neoplasm in obtaining a positive result. In the present study, no FP results were obtained due to the presence of concomitant diseases, in which accumulation of used radiopharmaceutical is possible, since the data on the presence of such diseases were taken into account in the analysis of scintigrams. The data obtained in this paper are in good agreement with the data obtained by other authors, as well as early Russian publications. It is worth noting that the data of domestic authors were obtained on a small sample, without specifying confidence intervals; the injected activity was less than in this study. In addition, the possibility of obtaining more information than using classical imaging methods (for SPECT/CT, the tissue with the pathological accumulation of 111In-octreotide appeared to be intact on CT), allows us to recommend the method as a method of choice in the diagnosis of NET of different localization. Conclusions: The method of somatostatin receptors scintigraphy using domestic analogue of somatostatin in the diagnosis of NET has a high efficiency (efficiency of the method, calculated as the average value of the parameters of sensitivity and specificity of 85 % (95 % CI: 66–100 %).
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