“The procedures used to identify CCSVI in MS patients are so subjective that operator bias cannot be eliminated. If a technician wants to find CCSVI, he or she can.”
CCSVI imaging is an emerging diagnostic practice. There is variability across imaging centers in machinery/tools, protocols followed, and the expertise of physicians and technicians. Because of this, there is opportunity for disagreement about types and degrees of stenosis, particularly because different imaging centers may be reviewing different images obtained from different machines via different methods.
That said, there are methods and procedures that produce substantial agreement about critical components of CCSVI.
First, the veins of some MS patients are so obviously atypical that there is little room for disagreement among observers. Here, veins are missing entirely, or obviously malformed (agenesis, hypoplasia). In these cases the vascular problem is apparent to physicians or researchers possessing even modest levels of experience. Commonly used non-invasive CCSVI diagnostic tools like ultrasound, Magnetic Resonance Venography (MRVs) and CT Venograms can reveal these larger venous problems. (These technologies can sometimes reveal more subtle problems as well.)
Second, a specific type of high resolution ultrasound called Duplex Ultrasonography provides reliable evidence of abnormal vascular conditions, particularly blood flow rates and reflux. The use of duplex ultrasonography, which combines Doppler interrogation with color-coded imaging displays, for diagnosing CCSVI was pioneered by Dr. Zamboni and his colleagues at the University of Ferrara, Italy. However, duplex ultrasonography requires specialized equipment and, in particular, skilled and experienced technicians and interpreters. Currently, CCSVI Alliance is aware of only one group - Dr. Robert Zivadinov’s team at the Buffalo Neuroimaging Analysis Center (BNAC) – that is using duplex technology for CCSVI diagnosis in the United States. Dr. Zamboni’s ultrasound technicians personally trained the BNAC team, but even with this training there has been a learning curve. Nonetheless, it cannot be overstated: Duplex ultrasonography has been proven capable of accurate CCSVI diagnosis, but only when performed by technicians and interpreted by physicians with significant training in CCSVI diagnosis and with substantial hands-on experience13.
Third, to confirm results obtained from other diagnostic methods, catheter-based venography (also called “selective venography”) allows doctors to see whether suspect areas of a vein are in fact pinched or occluded by viewing these areas in real-time by using locally injected contrast agents to highlight and x-ray specific vein segments. Note that catheter venography, typically considered the ‘gold standard’ for CCSVI diagnosis, requires an endovascular procedure, which introduces basic medical risks not associated with noninvasive diagnostic procedures like MRV, CT Venography, or Doppler ultrasound.
Lastly, it should be noted that in currently published studies, Dr. Zamboni's and Dr. Zivadinov’s Doppler technicians were blinded as to whether their patients had MS or not. In order to enhance the blinding, patients with disorders that present in a similar manner to MS were included in the control group. Thus, technician bias has been appropriately mitigated in several critical CCSVI studies.
In summary, CCSVI diagnosis is still in its infancy. To obtain reliable results, patients must have their scans performed at imaging centers with the most modern equipment, and, most importantly, by practitioners with documented history of CCSVI diagnostic training and experience, and who follow established CCSVI diagnostic protocols. Results obtained otherwise may be completely inaccurate or fundamentally misleading.