## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Preoperative Imaging** & **Ultrasonography** & **Planar scintigraphy** & **SPECT/CT** & **4D-CT** & **MRI** \\ \hline Sensitivity & 80–90\% & 44–88\% & 93\% & 88–92\% & NA * \\ \hline \hline \end{tabular}  
* Usefulness of MRI is controversial as motion artifacts may occur from swallowing and respiration as a result of long scan times.  
\end{table} 
Table 1: Sensitivities of preoperative imaging. MIBI molecule and negatively (\(-\)) charged mitochondria [23]. The tracer is actively taken up and stored in the mitochondria. The accumulation of the tracer is more pronounced and lasts longer in hyperactive parathyroid tissue than in the surrounding thyroid tissue [10; 24]. SPECT enables analysis of changes in parathyroid gland activity over time (early and delayed phases) [25]. The acquisition parameters of SPECT with gamma camera are INFINIA Hawkeye 4 (GE Healthcare), collimator: Low Energy High Resolution, number of projections: 60, static scan, matrix: \(128\times 128\), zoom: 2, time per projection: 20 s, pixel sizes: 2.1 mm, 1.6 mm; the low dose CT was used to create attenuation maps. The image reconstruction parameters of SPECT with usage of the Xeleris, version 2.17, reconstruction method: OSEM, reconstruction ramp filter: Qurecon Quant, prefilter Hann (0.9), 3D postfilter Hann (0.9; 10.0), number of iterations: 2, subsets: 10. Patients were examined with planar and SPECT/CT parathyroid scintigraphy following intravenous administration of \({}^{99m}\)Tc-MIBI 762 \(\pm\) 60.7 (range: 600-850) MBq with \"wash-out\" technique (dual-phase, single-tracer). The early phase (EP) started no later than 10 min after administration of the tracer, and the delayed phase (DP) was performed \(127\pm 28\) min later. Exported SPECT volumes used 2.209030 mm pixel spacing for all 3D directions. Automatic analysis of achieved volumes after the manual preselection of Volume of Interest (VOI) is possible using numerous computational approaches, but the quality of parameter estimation is the most important factor. Different criteria could be used for quality analysis. The difference between real and estimated volume could be analyzed using global parameters such as mean squared error (MSE), but positions and amplitudes of components after the separation are much more interesting from a medical analysis point of view. They are related to activities of small scale regions. Our database has two: EP and DP measurements. The achieved parameters are important for the research purposes of the project, because the results of mathematical quantification are tailored to the specific medical context of 332 patients examined with preoperative parathyroid SPECT/CT (\"wash-out\" technique) scintigraphy. Apart from SPECT/CT scintigraphy, the collected data set encompasses biochemical blood results (plasma PTH concentration, ionized calcium and inorganic phosphate concentrations), blood genotyping results (genotyping the cohort of patients for MDR1 (ABCB1) and MRP1 (ABCC1) genes, probably responsible for different radiotracer kinetics in two phases of SPECT/CT scintigraphy in different individuals), results of additional planar parathyroid scintigraphy and ultrasonography of the neck. The main problem to solve for our project is the influence of genetic factors which may be the reason for different behavior of \({}^{99m}\)Tc-MIBI in preoperative scanning [26]. In addition, a quantitative approach to SPECT uptake was taken into consideration. Finally, 70 patients underwent surgery and histopathological examination was performed. The exact information about the number of counts in particular VOIs are used to find the relation between pathology of proven tissue samples and clinical background.