Dicom conver to Nii

Hi, There,

I have a challenge that when I use 3D slicer to convert a ultrason DICOM files to nii files. I lost the quality of image by a new ultrason probe ( comparing to a probe we used before).

In the past, we have been using a GE probe in GE Voluson E10 :

Model: "RIC5-9-D,
Acquisition parameters: B177 degrees, V120 degrees, depth 7.7cm,
The obtained dicom document size is 54Mb, ( see attached link to download )
Then, the converted nii file size is 63Mb
The image is clear and has sufficient resolution.

However, we recently have a new GE probe,

Model: "RSP6-16-D,
Acquisition parameters: B50 degrees, V29 degrees, depth 4.2cm
Dicom document size 37Mb
The converted nii file size is 2.6Mb <= this is the problem, it become very small !!
The resolution of the picture is very low and very blurry.

you can find that the acquisition angle (B, V) of the original equipment (RIC5-9-D ) is relatively wide, and the acquisition angle of the new equipment (RSP6-16-D) is much narrow.

The problem we encountered is: Why does the DICOM document of the new device become very small when it is converted. The resolution Is poor.
Is there any parameter or setting I need to modify for smaller angle dicom file which I acquired by the new probe? or anything thing I can do to keep the same quality?

Hope it can be resolved, thank you.