There's research from Dr. Siskin on how those negative ultrasounds compare to what's found on actual venography
http://www.sirmeeting.org/index.cfm?do= ... s&abs=2088Quote:
The Diagnostic Utility of Ultrasound for Chronic Cerebrospinal Venous Insufficiency (CCSVI) in patients with Multiple Sclerosis
Authors:
J. G. Almond1, M. Englander1, K. Mandato1, S. Parikh1, G. Siskin1
Institutions:
1. Radiology, Albany Medical Center, Albany, NY, United States.
Purpose:
To evaluate the ability of ultrasound (US) to diagnose venous disease in patients with MS undergoing treatment for CCSVI.
Materials:
A retrospective analysis of all MS patients treated for CCSVI during an 8-month period was performed. The study population consisted of patients undergoing US of the internal jugular veins (IJV) within 24 hours of venography (CV). US was performed utilizing the protocol described by Zamboni, et al. A positive US met 2/5 criteria for CCSVI. A positive unilateral US met 2/4 criteria (without the transcranial evaluation of the deep cerebral veins). A positive CV was defined as one identifying a ≥50% stenosis in at least one vein, including the azygos vein. The US and CV findings were then compared.
Results:
416 patients were treated during the study period; the study population consisted of 310 patients (mean age 49 years; 30% male and 70% female). 224/310 patients (72%) had a positive US, and 155 (69%) of these patients had a positive CV; 86/310 patients (28%) had a negative US, and 66 (77%) of these patients had a positive CV (p=0.240). An ROC curve was generated (AUC=0.463). 300/310 (97%) patients underwent PTA of at least one vessel (215/224 with a positive US and 85/86 with a negative US) because venography showed either a ≥50% stenosis or a flow abnormality in association with a <50% stenosis; US therefore had a false negative rate of 99%. On the left side, 87/310 (28%) patients had a positive US, and 41 (47%) of these patients had a positive CV; 223/310 (72%) had a negative US, and 117 (52%) of these patients had a positive CV (p=0.472). On the right side, 63/310 (20%) patients had a positive US, and 28 (44%) of these patients had a positive CV; 247/310 (80%) had a negative US, and 130 (53%) of these patients had a positive CV (p=0.308).
Conclusions:
Findings on a Zamboni-protocol US are not associated with findings on contrast venography in light of the high false negative rate; 99% of the patients with a negative US had a significant stenosis and/or flow abnormality treated with angioplasty. A prospective study is needed to define the role of US and other modalities in the non-invasive diagnosis of CCSVI.
So if a patient has MS, they found that the patient has a 99% chance of having CCSVI found during venography even if he doesn't meet the criteria with the ultrasound. It's why Dr. Siskin's team stopped doing pre-procedure ultrasounds.
It sounds like your one abnormality criteria is no flow in the vertebral veins? Most IRs do not treat the vertebral veins. They are smaller than jugulars but can have malformed valves also. I don't know if this is an indirect sign of azygous blockage. The azygous can be looked at more directly via MRV or by venogram during the procedure itself. Not meant as medical advice.
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