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Cliniques Universitaires St-Luc Université Catholique de Louvain Brussels 1200, Belgium
We read with interest the article published by Abdelmoumene et al. [1] in the AJR. We congratulate the authors for their study concerning optimization of deep venous enhancement using elastic stockings for nonthrombosed veins. However, we have to mention to the authors that a variant of this "technical innovation" of CT venography has already been described in a study including 65 patients being assessed for pulmonary embolism on MDCT [2]. In the Materials and Methods section of that article, we stated that tourniquets were placed above the ankles and thighs for combined CT venography to avoid preferential opacification of the superficial veins just before the CT acquisition and that they were removed just before the abdominal scanning. Good to excellent opacifications were obtained in most patients. We did not report specific enhancement values in the veins using this method, but we found deep venous thrombosis with a sensitivity and specificity of 93% and 97%, respectively, which are comparable to the results obtained by Loud et al. [3].
We can speculate about elastic stockings or tourniquets to increase deep venous opacification, but the resulting difference in enhancement between the two techniques would probably not be significant. Therefore, we do not fully agree with the authors' statement in the introduction of their article that "this technique commonly used in conventional venography to increase deep vein opacification has not been tested on CT venography." We think that our study, which was performed with a similar technique, should have been quoted in the Discussion section of the article by Abdelmoumene et al. [1].
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Centre Hospitalier Universitaire Vaudois Lausanne 1011, Switzerland
We read with interest the comments by Dr. Coche et al. about our article [1] published in the April 2003 issue of the AJR. They point out several elements that merit reply:
Our article [1] does not quote the article by Coche et al. [2] published in 2001. I do apologize to Coche et al. for this omission. We regard Dr. Coche as a friend and a colleague in the European Society of Thoracic Imaging Council. In our defense, the data for our article were collected in 2000, approximately 1 year before the publication of the article by Coche et al. in AJR.
The article by Coche et al. [2] is a comparative study between CT phlebography and Doppler sonography that shows the high reliability of CT phlebography in terms of sensitivity, specificity, and predictive values. Conversely, our article is a technical note.
Coche et al. [2] used tourniquets placed above the ankles and the proximal ends of the thighs to improve the contrast enhancement of deep veins in the lower limbs. Our technical note describes another method, using elastic stockings that adapt in size to the patient's body habitus. The bandages enclose the lower limb from the ankle to the mid third of the thigh.
Our study quantified the degree of deep vein contrast enhancement, which ranged between 30 and 34 H. Similar measurements were not obtained by Coche et al. [2] in their patient cohort.
The use of tourniquets, elastic stockings, or bandages has been recommended since the late 1960s [3] as a practice for conventional phlebography. The experience of many institutions, when conventional phlebograms were still being acquired regularly, is that tourniquets placed at the levels of the ankle and of the proximal end of the thigh do not prevent contrast material from opacifying the superficial veins of the lower limb, particularly at the levels of the calf and of the distal third of thigh, through noncompetent venous anastomoses and perforating veins. Furthermore, the tourniquet placed at the level of the thigh occasionally induces a compression or even a complete obstruction of the superficial femoral vein. The use of adapted elastic stockings provides a smoother and more regular compression of the superficial venous network and never compresses or occludes the deep or the superficial femoral veins of the leg.
Finally, the protocols of our two studies are completely different. Indeed, Coche et al. [2] compared CT phlebography with Doppler sonography (or with conventional phlebography in a few patients), and we compared the attenuation values of the opacified deep veins of the lower limb in two groups, one group with elastic stockings and the other group without [1].
In conclusion, we apologize for not having quoted Coche et al. [2] in our article. We do not share their opinion when they speculate that the use of elastic stockings versus tourniquets would probably not modify the enhancement of the deep veins of the lower limbs significantly differently. This remains to be proven and could be a topic for bicentric clinical research.
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