CT venography delivers roadmap for surgical planning

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Three-dimensional CT scans provide a comprehensive view of complex varicose veins in the lower extremities, according to a study performed at Seoul National University Hospital in Seoul, South Korea.

Three-dimensional volume-rendered image obtained at opacity–transparency function setting for muscle planes shows enlarged left great saphenous vein (black arrow) and tortuous varicose veins (asterisk) in a 51-year-old woman with varicose veins. Perforating veins are vividly shown, and paratibial (white arrow) as well as posterior tibial (arrowhead) perforating veins are evident. Image and caption courtesy of the American Roentgen Ray Society.  

Chronic venous disease of the legs is one of the most common conditions affecting people of all races. Because of the ability to evaluate hemodynamic information and its convenience and availability, duplex sonography is considered the reference standard for noninvasive anatomic and functional assessment of venous reflux. However, ultrasound is limited in its assessment of varicose veins, because of its limited field of view. As such, deep-seated varicose vein pathways and major perforators can be missed.

Whal Lee, MD, and colleagues conducted CT scans on 100 consecutive patients who were referred for evaluation of varicose veins over a three-month period. Exams were performed on a GE Healthcare 8-slice LightSpeed Ultra or on a 16-slice Siemens Healthcare Sensation 16 CT system using a non-ionic contrast agent (Ultravist 370, Bayer Healthcare).

Thin-section axial images were reformatted on a workstation running Infinitt’s Rapida 3D reconstruction software and evaluated by two experienced readers (AJR 2008; 191:1186-1191).

“To evaluate the saphenofemoral and saphenopopliteal junctions, we used axial images and maximum intensity projection and multiplanar reformatted images in the interactive image plane,” the authors wrote.

“It takes about one minute to upload over 1,000 thin axial CT images for real-time 3D viewing,” co-author Jin Wook Chung, MD, told Cardiovascular Business News.

Chung added, “In making routine views in predefined viewing angles and marking and measuring dilated perforators related to varicosity, we usually spend an additional five to 15 minutes, depending on the complexity and severity of varicosity.”

For the study, investigators evaluated the images for overall quality and then analyzed for factors believed to affect image quality. The researchers reported that the quality of the 3D images was excellent in 76 cases, fair in 21 and poor in three.

The 3D CT scans also gave the physicians a closer look at the great saphenous vein in 99.5 percent of all lower extremities being examined.

“Contrast-enhanced CT venography can show the calf veins with clear anatomic landmarks such as muscle and bone, and use of this technique facilitates detection of abnormalities of the deep calf veins,” he said.

The 3D images from the study provided surgeons a more comprehensive way to see the disease, allowing them to better plan their surgery to prevent recurrence of varicose veins, according to the researchers.

Chung said that it is routine for their vascular surgeons to order 3D CT venography together with Doppler ultrasound for patients with varicose veins. The combination can yield better surgical outcomes for patients.

However, they do not routinely follow-up patients after surgery with 3D CT venography. “We use it only in case of postoperative recurrence,” he said.

To optimize venous enhancement, researchers used a three-minute delay from the time of injection. They noted that the bolus-tracking method is not optimal owing to the different circulation times in the venous system. A direct injection of diluted contrast medium also is not preferred as not all venous channels in the lower extremity are filled, especially varicose veins, the authors said.

David E Allie, MD, chief of cardiothoracic and endovascular surgery at Cardiovascular Institute of the South in Lafayette, La., said that CT venography is analogous to using CT angiography to identify, treat and plan interventional procedures for patients with peripheral arterial disease.

“More tools are available to treat peripheral arterial and venous disease and more procedures are being done,” Allie said. “The amount of diagnostic information we get from advanced CT imaging has a lot to do with our increased ability to treat these patients.”