ItemList.cs

namespace WpfApplication1.Gw
{
    class ItemList
    {
        public byte[] Image { get; set; }
        public string Title { get; set; }   

    }
}

mainWindow.xaml

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApplication1"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>

        <ListBox Name="ListBox" Initialized="ListBox_OnInitialized">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <ListBoxItem>
                        <StackPanel Orientation="Horizontal">
                            <Image Source="{Binding Image}" Width="25"/>
                            <TextBlock VerticalAlignment="Center" Text="{Binding Title}"></TextBlock>
                        </StackPanel>
                    </ListBoxItem>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        
    </Grid>
</Window>

mainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Windows;
using WpfApplication1.Gw;
using GW2NET;
using GW2NET.Common;


namespace WpfApplication1
{

    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ListBox_OnInitialized(object sender, EventArgs e)
        {

            var service = GW2.V2.Items.ForDefaultCulture();
            var iconService = GW2.Rendering.RenderService;
            IPageContext ctx = service.FindPage(pageSize: 10, pageIndex: 0);

            var items = new List<ItemList>();
            foreach (var page in service.FindAllPages(ctx.PageSize, ctx.PageCount))
            {
                foreach (var itemContent in page.Value)
                {
                    byte[] png = iconService.GetImage(itemContent, "png");
                    items.Add(new ItemList() { Title = itemContent.Name, Image = png });
                }
            }


            /**
            Litle hardcoded old stuff 
            items.Add(new ItemList() { Title = "Learn C#", Image = "Images/Bandage.png" });
            items.Add(new ItemList() { Title = "Wash the car", Image = "Images/Bandage.png" });
            */
            ListBox.ItemsSource = items;

        }
    }
}