Gerard O’Sullivan, Galway, Ireland, spoke in the Venous Challenges sessions on Tuesday 9 April about imaging for iliac deep vein thrombosis and the best modalities to use. He told delegates that computed tomography pulmonary angiography (CTPA) and CT venography are his preferred modalities.
I do a lot of acute iliofemoral deep venous work, and I do not think there is one modality that covers it all. If I had lots of MRI scanners and a lot of time I would use MRI much more, but I do not. When you are doing iliofemoral deep venous work for thrombosis, what kills the patient is pulmonary embolism and right ventricular dilatation. In my opinion, you need to evaluate the right ventricle and the pulmonary arteries when you are evaluating this patient. You can do that by a variety of techniques, but for me CTPA is the quickest,” he said.
Comparing CTPA and CT venography vs. MR venography, O’Sullivan noted that CT is quicker but involves the use of radiation. “It is less elegant but you can see more the inside of vessels,” he stated. “We looked at our data and, despite previous works suggesting that one-third of patients had positive CTPA with deep vein thrombosis, we found that 79% of our patients had had a pulmonary embolism by the time they presented for iliofemoral deep venous acute treatment.”
He explained that what physicians should be looking for is not pulmonary embolism, but right ventricular dilatation. O’Sullivan said that the pulmonary arteries should be assessed in several ways: isotope plus direct venography, isotope or CTPA plus ultrasound of the legs, CTPA plus CT venography, MR pulmonary angiogram plus peripheral MR venography, or echocardiography plus peripheral MR venography.
“In practical terms, for me CTPA plus CT venography is the better method as I can do it quickly and have all the information I need. I also use ultrasound to assess the popliteal vein as the further down you go more difficult it is to interpret CTPA,” he said.
He explained that in Galway he performs indirect CV venography with standard peripheral intravenous injects at same sitting at CTPA, 20G cannula in wrist or elbow, 150cc iodinated contrast, image at 150s, and 5mm cuts from diaphragm to mid-calf. “The pictures are not comparable to CT angiography but with experience are easily adequate for diagnosis.”
O’Sullivan concluded by saying that CT venography and MR venography are essential in addition to ultrasound in preoperative assessment of iliac venous thrombosis. “We feel limited ultrasound with CTPA and indirect CT venography offers the most rapid diagnostic combination method to assess pulmonary embolus, right ventricular dilatation, inferior vena cava thrombus, acute vs. chronic disease above and below the groin and extra-vascular lesions eg tumour. But other physicians use other methods equally well or better.”