Facultad de Ciencias de la Salud

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Browsing Facultad de Ciencias de la Salud by Author "Santiago Valenzuela Sosa"

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    New option for reliable fast indirect volumetry: the XYZ geo method
    (2023-03-03) Santiago Valenzuela Sosa
    Objectives: present a simple, fast and reliable method to determine the volume of brain pathologies by applying the formula of the geometric figure that best fits the lesion studied. Material and method: retrospective study on 403 tumor lesions of different histology found in 172 patients treated by radiosurgery at the Dominican Gamma Knife Center (CGKD), using 1.5 and 3.0 Tesla MRI images with thin cuts for three-dimensional reconstruction. The volume of each of them was determined following the voxel method (planimetry) in which the edges of the lesion are painted in each slice. We immediately proceeded to determine if the lesion was Ellipsoidal, Cubic, Cuboid or other. More than 98% of the lesions were ellipsoid-shaped, about 1% were cubic. Applying the formula of the figure in question in each case and starting from the center of the structure, the XYZ diameters used internationally to define the stereotactic dimensions of the space were drawn. Thus, the Theoretical Volume was determined, which was compared to the Real Volume of each lesion using the Student’s T Test to establish the Mean between two measurements, then they were correlated using the Wilcoxon Test and the Spearman’s Rang Test. Results: If the lesion was ellipsoidal and we used the correct formula, the result was close to 93% of the Real Volume. If the Ellipsoid formula was applied to a cubic lesion, we obtained 178% of the Real Volume. If a Cubic lesion was measured with the corresponding formula, the result only exceeded the Real Volume by 12%. Conclusion: the XYZ Geo Method offers an option for rapid indirect volumetry very close to the real volume of the intracranial lesion if the geometric formula that best defines the lesion studied is applied, respecting the principles established for measuring its diameters on an imaging platform with option to calculate the three dimensions of stereotactic space (XYZ).
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    Rapid indirect hippocampal volumetry using the XYZ geo method: A useful tool in the diagnosis of cognitive impairment
    (2024-01-10) Santiago Valenzuela Sosa
    Objectives: to compare and validate the doses determined according to the novel method for calculating doses in radiosurgery called the Sosa Model (MS) with the dose protocols of national and international institutions. Material and Method: retrospective study on 403 tumor lesions of different histology found in 172 patients treated by radiosurgery at the Gamma Knife Dominican Center (CGKD), using MRI images of 1.5 and 3.0 Tesla with protocol for neuronavigation. In MS, the Sosa Score (SS) is obtained by adding 3 scores to a constant of 10Gy: Volume Score (VS), Radioresistance Score (RS), Eloquence Score (ES) of the lesion, complying with the formula that supports it. : SS= VS+RS+ES+10. Using the Wilcoxon Signed-Rank Test, it was compared with the conventional doses used in the CGKD, which are similar to those used internationally. Results: most lesions received between 12 and 24 Gy, calculated by both methods. Of the meningiomas treated in the CGKD, 65% received a dose of 12 to 14 Gy. Most of the doses suggested by the MS were between 15 and 18 Gy. On average, metastases treated in CGKD received between 16 and 24 Gy (220 of 247, 89%). The doses recommended by the MS were very close, ranging between 15 and 21 Gy (232 of 247, 93.9%). In Non-Functional Pituitary Adenomas, the MS (17-18 Gy) yields doses above those of the CGKD (12-16 Gy) since it does not include adaptations to protect the visual pathway. In Functional Pituitary Adenomas, MS falls below the particularly high doses (25 to 35 Gy) internationally recommended. The Acoustic Neuromas all received between 12 and 13 Gy in the CGKD and most of the doses recommended by the MS were between 14 and 15 Gy. Conclusions: Comparing the doses used by CGKD and those recommended by MS, there is a close proximity when it comes to Acoustic Neuromas and Metastases, but an important difference when it comes to Adenomas and Meningiomas. When applying the Wilcoxon Signed Rank Test to the 403 lesions studied, the mean difference between the two dose calculation systems was 0.23 Gy (95% CI: -0.127-0.60)
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    Validation of a new method for dose determination in radiosurgery: “The Sosa Model”
    (2024-04-04) Santiago Valenzuela Sosa
    Goals: to demonstrate the validity of the XYZ Geo Method of rapid indirect volumetry 37, 38, 39 using the simplified geometric formula of the XYZ/1910 ellipsoid, to obtain a volume of the anterior part of the hippocampus (Ammon’s Horn + Body = AA) or the complete Hippocampus, including the tail (AA + Tail = Complete Hippocampus = HarP = Harmonized Protocol 24), very close to the real volume determined by the voxel method (planimetry). Material and Method: prospective study, which took place between January 2020 and July 2022, of 100 Dominican adults, divided into a control group of 60 patients with normal cognition divided into 3 age groups (20-40, 41 to 60 and 61 to 80 years). and a case group of 40 patients complaining of cognitive problems (aged 41 to 60 and 61 to 80). The Folstein Mini Mental State Examination (MMSE) adapted to Latino patients was administered.15. All benefited from a 1.5 Tesla MRI with 1-1.5 mm slices for three- dimensional reconstruction including non-contrast T1, FLAIR, T2 and TOF sequences. The Principal Investigator (PI) performs real volumetry of the Anterior and Complete Hippocampus using voxels (planimetry), processing these Magnetic Resonance images on the Elekta Workstation Gamma Plan 10 platform of the Dominican Gamma Knife Center of CEDIMAT in the Plaza de la Salud de Santo Sunday, Dominican Republic. Next, the PI performs the indirect volumetry of these structures by applying the simplified formula of the Ellipsoid, following the guidelines of the XYZ Geo Method for rapid indirect volumetry of intracranial structures39, determining their largest diameters Axial (X), Sagittal (Y) and Vertical (Z) on the aforementioned Platform. For each of these patients, blindly with respect to the PI results, the Research Assistants (RA), using the Magnetic Resonance CD in which the RadiAnt DICOM Viewer software with capacity for millimeter measurement is encrypted, determine rapid indirect volumetry of the Anterior Hippocampus (AA) and complete Hippocampus (HarP) applying the aforementioned methodology. The data collected was processed using measures of central tendency and dispersion in the Microsoft Excel 2016 platform. Results: The indirect volumetry of the hippocampi studied carried out by the PI using the simplified geometric formula of the ellipsoid had an average approximation of 101.7% with respect to the real volume determined by voxels. The measurement carried out by the RAs approached 99.6% of the real volume of the hippocampi studied. The average time to perform the actual volumetry of the Anterior Hippocampus (AA) by the PI was more than 11 minutes, while using the formula for rapid indirect volumetry the hippocampal volume could be calculated in less than a minute. Conclusion: indirect volumetry of the hippocampus applying the guidelines of the XYZ Geo Method 39 and using the simplified geometric formula of the ellipsoid, it is a reliable and rapid alternative to determine the health and integrity of this important anatomical marker of cognitive and seizure health, even if it is used by non-neurospecialist doctors.