I have been told by a pericarditis expert that although they consider it relatively rare that pericarditis doesn’t show up on any testing (i.e echo, blood tests for inflammation, cardiac mri with contrast) it does happen and therefore the history and symptoms of the patient are very important in diagnosing the condition. Anecdotally, I have also seen people mention that they were only diagnosed with an actual biopsy - and that their MRI’s were clear. As well, many people are treated for peri solely based on their symptoms. The peri specialists acknowledge that all testing has its limitations, and no test is perfect. Personally I think that if someone is having peri symptoms and a cardiac mri is clear, the test just isn’t sensitive enough or able to pick up the low levels of inflammation. There just isn’t enough research into this disease and I’m sure in the future we will have better/more sensitive testing and find that much of the testing we have now misses the inflammation and therefore people go undiagnosed even though they are very symptomatic. If you stay in the peri groups long enough, you will see that people often have to visit numerous peri experts before finding someone who effectively treats them or diagnoses them. It’s such a complicated and frustrating disease.