Sorry for the delay in getting on-line...I have been away from my office for the past several days.
It has been our experience that the "halo" mentioned by Schmidt, et al. is only likely to be seen in patients who are presenting late for diagnosis and who have been untreated at the time of study. You can use a 2-fold velocity increase (compared to the more proximal vessel of normal diameter) to pin-point areas of stenosis, but you are still left with the problem of trying to differentiate atherosclerotic disease from giant cell arteritis and a velocity increase may not always be present. The B-Mode image component of the study demands a very high resolution system. I do not like to use the CL 10 probe for this because it has not been optimized for clinical use ( only OR) and the near field image is not as crisp as you need to have it. You might want to use the L10-5 with a stand-off pad. You can differentiate temporal arteritis from atherosclerosis by the fact that TA is acoustically homogeneous and focal in nature; atherosclerotic disease is heterogeneous, with irregular surfaces, and is diffuse along the course of the frontal and parietal branches. The artery may appear to be slightly dilated in areas of TA, due to the inflammatory reaction associated with this disease.
In summary, you are likely to see a continuum of arterial changes that will pinpoint TA: 2-fold velocity increase in the majority of cases, but not all; acoustically homogeneous thickening of the arterial wall; slight dilatation in the acute phase, and, perhaps, the classic Schmidt "halo" later on. It is important to try to image these patients before they begin steroid therapy. We are continuing iur research and hopefully will have more helpful, and definitive, criteria for you by next year.
Marsha M. Neumyer, BS, RVT
Assistant Professor of Surgery
Director Vascular Studies Section/Surgery
The Pennsylvania State University College of Medicine
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>>> "O'Brien, Carmen" <[log in to unmask]> 09/18 10:31 PM >>>
Stewart, We tried to scan pt. for Temporal Arteritis and had Many patients
with a positive biopsy and no temperal artery "halo", I am not sure if any
one out there has any protocols other than obvious areas of narrowing within
the Temporal artery ...we use our "entos" ATL scanhead. Also....the
Temporal artery is extracranial....not necessarily near any temporal
window...excess power would not be a problem unless you were using TCD power