Cece, this is a very confusing but very important concept. I hope all the readers stay with this because this is going to be an important determinant of the quality of the service.Cece wrote:I understood this better today than the first time I read through it.drsclafani wrote:Sensitivity of 70% and specificity of 22% leave much to be desired. 30% of patients with positive US results will undergo unnecessary venography and 76% of patients who have a negative ultrasound will not get a venogram that can diagnose and treat their ccsvi
According to the Albany data's sensitivity and specificity results, ultrasound would not a very good screening test. it misses too much disease and adds too much cost by doing venography in too many patients without disease.
is that understandable? The conclusions are debatable but not based upon the data of their paper.
The use of IVUS might lower the false positive rate, with the false positives becoming accurate positives if ivus showed that venography is missing some stenoses that had been picked up by doppler ultrasound pre-imaging, but it's speculation because IVUS wasn't used.
I have to read the abstract again. http://www.sirmeeting.org/index.cfm?do= ... s&abs=2088
A false positive is a test that is called positive when it is actually negative. That should not be the problem with CCSVI. Most series are reporting at least two veins abnormal in CCSVI.
The use of IVUS generally lowers the false negative rate of venography. in other words, venograms that are interpreted as normal (or negative) (or absent abnormality) when IVUS shows an abnormal valve, web or septum are FALSE NEGATIVE VENOGRAMS. Thus IVUS lowers the false negative rate and increases the true positive rate. If the prevalence of the abnormality is high, like CCSVI in MS, then a group with a high negative rate should use IVUS to weed out the false negatives. THAT IS IIMPORTANT.
And it's not just the idea of detecting a stenosis or treating a vein. Some of the physicians are admitting they are performing angioplasty based upon flow disturbances and arbitrarily dilating lots of the vein, especially azygous, without LOCALIZING the abnormality.They are not seeing the cause of the flow disturbance.
keep asking questions. this is important in the evaluation of diagnoses and therapeutic technical outcomes.