Intraclass Correlation for test retest

#1
I have a problem with reproducibility assessment.

I am measuring the amount of scar tissue in hearts by 7 different methods. There is no goldstandard test so i cannot assess accuracy. I am interested in the most reproducible test.

I have measured the scar twice using the 7 methods as has a colleague of mine.

can i use intraclass correlation to assess both interobserver and intraobserver reproducibility?

Which ICC should i use - I think 2 way random?

one other problem. i have measured the scar in the same patient on more than one slide. so there will be some clustering? Is this a big problem? is there a way to adjust for this?

I have SPSS.

Thanks very much in advance

Andy