Comparison of Sonographic and CT Guidance Techniques

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Abstract
OBJECTIVE. Procedure times for percutaneous biopsies were compared for various guidance techniques including helical CT, CT fluoroscopy, sonography with an attached needle guide, and freehand sonography with computer guidance. MATERIALS AND METHODS. Three interventional radiologists experienced in CT-and sonographically guided procedures performed biopsies on a phantom model. The phantom simulated hepatic metastases of various sizes and depths with subcostal or intercostal locations. Lesion sizes were 7, 10, and 20 mm, at 3- and 7-cm depths. Using self-aspirating needles, two passes were performed in each lesion. Mean procedure time per biopsy pass was calculated. A two-tailed Student's t test was used to compare guidance techniques. RESULTS. Mean procedure time per biopsy pass for the four guidance techniques was sonography with a needle guide, 36 ± 9 sec; sonography with computer guidance, 43 ± 10 sec; helical CT, 146 ± 42 sec; and CT fluoroscopy, 50 ± 18 sec. CT fluoroscopy required 2.6 ± 1.0 sec per biopsy. Helical CT required more procedure time than sonography with a needle guide, CT with computer guidance, and CT fluoroscopy (p < 0.0001). Sonography with a needle guide required less procedure time than sonography with computer guidance (p < 0.002) and CT fluoroscopy (p = 0.0003). Procedure times for CT fluoroscopy and sonography with computer guidance were not statistically different (p = 0.06). CT and sonographic guidance were equally effective regardless of lesion size, depth, or location. CONCLUSION. Traditional sonographic biopsy techniques are faster and more cost-effective than traditional CT techniques; however, CT fluoroscopy offers the localization advantages of CT with improved procedure times.