As we know,Clarity of the image is decided by its Spatial Resolution but not by Pixel Resolution.

CT have high Spatial Resolution but MRI have comparable Spatial Resolution to CT&far better Contrast Resolution than CT-So,MRI is the BEST to demonstrate Anatomy,especially in parts containing more soft tissue[Eg:Brain]&CT is the BEST to demonstrate Bony Anatomy.

They had a low resolution

You could tell because low resolution makes for a pixelated picture, and high resolution settings, you cannot tell.

major advantage of spiral CT is higher resolution and the ability to reconstruct images anywhere along the length.Although spiral is more advantageous for many applications, conventional CT is still a superior and precise method for imaging many tissues.

In order to find a high resolution world map, you should search for high resolution world map on an online search engine under "images." Most image websites will allow you to specify the resolution of the image.