Saving data in one result table for multiple ROI's over multiple images

Hi all
I have a series of images and rois that I would like to run a specific plugin on (Roughness calculations). Lets say I have 6 images and 8 rois. I then want to end up with 6 csv files each containing the data from the 8 rois. The problem is that I cannot make ImageJ store the data in the same result table. Every time I run a loop it overwrites the previous data and I then end up with six csv tables each with data from one roi only from the last image of the bunch. Any ideas of how I can go about this? My code is below thanks in advance

label = newArray(“A”,“B”,“C”,“D”,“E”,“F”,“G”,“H”,“I”,“J”,“K”,“L”,“M”,“N”,“O”,“P”,“Q”,“R”,“S”,“T”,“U”,“V”,“W”,“X”,“Y”,“Z”);

//Importing and renaming ROI´s from file directory
dirRoi = getDirectory(“Choose Source Directory”);
listRoi = getFileList(dirRoi)
roiManager(“Open”, dirRoi + listRoi[0]);
nroi = roiManager(“count”);
for (r = 0; r <= nroi; r++) {
roiManager(“rename”, r+1);

//Defining the function that I want executed upon all ROI’s

function Surfacedescriptors() {
run(“Roughness calculation”);

//Get directory to folder of images that are to be processed
dirImg = getDirectory("Choose Source Directory ");
dirResults = getDirectory(“Choose Source Directory for result table”)//directory to folder, where results are to be stored.
listImg = getFileList(dirImg);

//Creating the for loop that is supposed to run roughness calculations on all the specified ROIs on all images from the directory one by one
for (i=0; i<listImg.length; i++) {
for (r = 0; r<=nroi; r++) {
saveAs(“Results”, dirResults + label[r] + “.csv” );