Precision and comparison of CT-, MRI- and X-ray-guided interventions in lumbar facet infiltration - an experimental study

We evaluated the accuracy of the needle tip representation by different ima ging techniques for the guidance of facet infiltrations. For visualisation of the lumbar facet joints we used a high-field magnetic resonance tomograp h (MRT) with a 2.0 Tesla field and 3.5 mm slice thickness, an open low-fiel d magnetic resonance tomography (MRT) with an 0.064 Tesla field and 9 mm sl ice thickness, and IMATRON electron beam computed tomograph (EBCT) with a s lice thickness of 6 mm, and a mobile C-arm fluoroscope. The study was perfo rmed on 4 human cadaveric lumber spine preparations, each of which had 8 fa cet joints. Under imaging control, special injection needles were placed as close as possible to the facet joint space. Following placement of he need le, all specimens were scanned with the electron beam tomograph using a sli ce thickness of 1.5 mm. The thin-slice study served as the gold standard. T he distance between the tip of the needle and the facet joint was measured in all the images. Comparison of the different modalities with the gold standard revealed the following results: 1) median values of the absolute differences were 1.25 mm for high-field MR I, 1.35 mm for 6 mm EBCT, 2.05 mm for low-held MRI, and 2.30 mm for X-ray f luoroscopy. 2) While there was no statistically significant difference in the accuracy of tip localization between high-field MRI and 6 " EBCT (p = 0.293), both s ystems were more precise than low-field MRI (p = 0.04) and X-ray fluoroscop y (p = 0.009). When choosing the best imaging technique, such additional factors as radiat ion, costs and time, must also be considered. Provided necessary radiologic al precautions are taken, and assuming careful pre-interventional planning, CT. EBCT and X-ray fluoroscopy are currently more effective than the expen sive, time-consuming and costly magnetic resonance tomography.