ADC vērtību uzticamība fokālās smadzeņu patoloģijās difūzijas uzsvērto attēlu sekvences fantomā.
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Date
2020
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Rīgas Stradiņa universitāte
Rīga Stradiņš University
Rīga Stradiņš University
Abstract
Darba mērķis. Difūzijas uzsvērto attēlu sekvence (DWI) ir magnētiskās rezonanses metode, kam ir augsts potenciāls galvas smadzeņu bojājumu diagnostikā. Lai izvērtētu DWI sekvences īpašības, darba mērķis bija izvērtēt, vai intereses apgabala (ROI) lokalizācija, izmērs un slāņa lokalizācija ietekmē acīmredzamo difūzijas koeficientu (ADC).
Materiāli un metodes. Tika izveidots 5% saharozes-agara smadzeņu parenhīmas imitācijas fantoms (diametrs - 21 cm, vidējais ADC - 1.87 x 10-3 mm2/s ), kas saturēja četrus cilindrus (diametrs - 2.7 cm) ar četrām vielām - 50% saharozes-agars, rapšu eļļa, 2.5% mannīts un ūdens. Šīs vielas reprezentē dažāda tipa audus. Datu mērījumi tika veikti ar 3T MRI aparatūru. ADC-DWI mērījumi veikti izmantojot trīs dažādus ROI izmērus (10, 35, 100 mm2) un starp diviem dažādiem slāņiem (attālums 1.2 cm). Mērījumi veikti katra cilindra vidū un pie iekšējās robežas. Rezultātu apstrāde veikta ar pāru t-testu un Vilkoksona rangu zīmju testu.
Rezultāti. Statistiski nozīmīgu ADC atšķirību (p<0.0005) ADC sadalījumā starp dažādām lokalizācijām var vērot visos cilindros. Attiecīgās atšķirības 10, 35, 100 mm2 izmēru ROI bija 56,2%, 66,05%, 70,28% saharozes cilindrā, 86.6%, 86.5%, 90.4% eļļas cilindrā, 10.7%, 10.5%, 11.1% mannīta cilindrā un 15%, 14.9%, 15.2% ūdens cilindrā. ROI izmēram bija ietekme uz ADC tikai 50% saharozes cilindrā - 14% starp 10, 35 mm2 ROI un 16.1% starp 35 un 100 mm2 ROI. Slāņa lokalizācijai bija statistiski nozīmīga (p<0.0005) ietekme uz ADC tikai ūdens (7.5%) un mannīta cilindrā (3.2%)
Secinājumi. ROI lokalizācijai ir ietekme uz ADC bojājuma ietvaros. Solīdās zemas difūzijas vielās ADC var ietekmēt ROI izmērs. Slāņa lokalizācija var ietekmēt ADC audos ar brīvās difūzijas restrikciju.
Objectives. Diffusion-weighted imaging (DWI) is a magnetic resonance imaging technique that has a high potential in diagnostics of brain lesions. To evaluate its characteristics, the aim of the study is to assess whether apparent diffusion coefficient (ADC) is affected by the position, size of ROI and the slice location. Materials and methods. A 5% sucrose-agar gel brain tissue DWI-equivalent phantom (diameter – 21 cm, mean ADC – 1.87 x 10-3 mm2/s ) containing four cylindric compartments (diameter – 2.7 cm) with either 50% sucrose-agar gel, rapeseed oil, 2.5% mannitol solution or water representing different types of tissues was designed and scanned with a 3T MRI system. ADC-DWI using 3 ROI sizes of 10, 35, 100 mm2 were measured within two distant slices (1.2 cm) in the middle of each compartment and along their inner border. Results were evaluated with a paired samples t-test and Wilcoxon Signed Rank test for comparing related samples. Results. A significant ADC difference (p<0.0005) was found in the ADC distribution between the middle and along the inner border of each compartment. Respective ADC differences for the 10, 35, 100 mm2 ROI were 56,2%, 66,05%, 70,28% for sucrose compartment, 86.6%, 86.5%, 90.4% for oil compartment, 10.7%, 10.5%, 11.1% for mannitol compartment and 15%, 14.9%, 15.2% for water compartment. ADC differences were affected by the ROI size only in the sucrose compartment – 14% between 10, 35 mm2 ROI and 16.1% between 35, 100 mm2 ROI. ADC was significantly (p<0.0005) affected by slice location only in the water (7.5%) and mannitol compartment (3.2%). Conclusions. ADC is affected by the position of ROI within the lesion. In solid low-ADC substances, ADC values can be influenced by ROI size. ADC in tissues of free diffusion restriction may be affected by slice location.
Objectives. Diffusion-weighted imaging (DWI) is a magnetic resonance imaging technique that has a high potential in diagnostics of brain lesions. To evaluate its characteristics, the aim of the study is to assess whether apparent diffusion coefficient (ADC) is affected by the position, size of ROI and the slice location. Materials and methods. A 5% sucrose-agar gel brain tissue DWI-equivalent phantom (diameter – 21 cm, mean ADC – 1.87 x 10-3 mm2/s ) containing four cylindric compartments (diameter – 2.7 cm) with either 50% sucrose-agar gel, rapeseed oil, 2.5% mannitol solution or water representing different types of tissues was designed and scanned with a 3T MRI system. ADC-DWI using 3 ROI sizes of 10, 35, 100 mm2 were measured within two distant slices (1.2 cm) in the middle of each compartment and along their inner border. Results were evaluated with a paired samples t-test and Wilcoxon Signed Rank test for comparing related samples. Results. A significant ADC difference (p<0.0005) was found in the ADC distribution between the middle and along the inner border of each compartment. Respective ADC differences for the 10, 35, 100 mm2 ROI were 56,2%, 66,05%, 70,28% for sucrose compartment, 86.6%, 86.5%, 90.4% for oil compartment, 10.7%, 10.5%, 11.1% for mannitol compartment and 15%, 14.9%, 15.2% for water compartment. ADC differences were affected by the ROI size only in the sucrose compartment – 14% between 10, 35 mm2 ROI and 16.1% between 35, 100 mm2 ROI. ADC was significantly (p<0.0005) affected by slice location only in the water (7.5%) and mannitol compartment (3.2%). Conclusions. ADC is affected by the position of ROI within the lesion. In solid low-ADC substances, ADC values can be influenced by ROI size. ADC in tissues of free diffusion restriction may be affected by slice location.
Description
Medicīna
Medicine
Veselības aprūpe
Health Care
Medicine
Veselības aprūpe
Health Care
Keywords
Acīmredzamais difūzijas koeficients, magnētiskās rezonanses attēli, difūzijas uzsvērtie attēli, smadzeņu fantoms, Apparent diffusion coefficient, magnetic resonance imaging, diffusion-weighted imaging, brain phantom