Not sure if you got my PM, but I'll post on your original thread too.
Type 1: This represents inflammatory end-plate changes. On MRI, you'll see decreased signal on T1 and increased signal on T2.
Type 2: This represents focal fatty marrow conversion. On MRI, you'll see increased signal on T1 and T2.
Type 3: This represents sclerosis and you'll see decreased signal on T1 and T2.
There was a recent article by Butterman in The Spine Journal that showed that patients with advanced DDD and chronic LBP have better responses to ESIs (Epidural Steroid Injections) and ISIs (Intradiscal Steroid Injections) if there is evidence of Modic Type 1 changes.
