C-arm cone beam computed tomography needle path overlay for image-guided procedures of the spine and pelvis.

INTRODUCTION: The aim of this study is to report our early clinical experience using C-arm cone beam computed tomography with fluoroscopic overlay for image guidance during percutaneous needle procedures of the spine and pelvis. METHODS: Twelve consecutive patients (four female and eight male patients; mean age, 64 years; range, 47-74 years; SD ± 7.6 years) who underwent percutaneous biopsy of the spine and pelvis for suspected metastasis (n = 12), spondylodiscitis (n = 6), abscess (n = 5) or bone tumour (n = 1) were prospectively included between March 2009 and November 2010. The procedures were performed on the Allura Xper FD20/20 (Philips, Best, the Netherlands) using cone beam computed tomography (XperCT) with the C-arm combined with fluoroscopic overlay for needle guidance. Based on an initial XperCT, entry and target points were defined using dedicated guidance software (XperGuide). The needle path was visualised in various reconstructed planes and could be adjusted when considered necessary. For percutaneous interventions, the entry view (overlay of entry and target point in the bull's eye fashion), the progression view (perpendicular to the entry view) as well as two additional views could automatically be piloted to with the C-arm system. Needle navigation was supported by a biopsy guidance device (Seestar, Radi, Uppsala, Sweden). Correct needle positioning was confirmed with a second XperCT acquisition. Technical success was defined as any target point reached via the planned needle trajectory with a distance of final needle tip within 5 mm of the planned target point in any direction. RESULTS: In all 12 patients, target areas could be defined based on XperCT data. In 11 of 12 (92%) cases, the target point was successfully reached on the planned trajectory with a mean error of 2.8 mm (range, 0.5-9.4 mm; SD, 2.4 mm). No peri- or post-interventional complications occurred. CONCLUSION: XperCT-guided interventions with the XperGuide system seem a safe and reliable tool for percutaneous needle interventions of the spine and pelvis. The advantage of the technique when compared to CT- or fluoroscopy-guided interventions needs to be determined in a comparative study of a larger scale.

Mono- versus bisegment reconstruction algorithms for dual-source computed tomography coronary angiography.

OBJECTIVE: To compare the image quality of mono- versus bisegment reconstruction algorithms for dual-source computed tomography coronary angiography (CTCA). MATERIALS AND METHODS: Eighty consecutive patients (27 women; average age, 60 +/- 12 years) were randomly assigned to 2 different CTCA scanning protocols: 40 patients (group A) underwent dual-source CTCA with a heart rate (HR)-dependent pitch adaptation with datasets reconstructed using the monosegment algorithm; 40 patients (group B) underwent CTCA at a fixed pitch of 0.2 and datasets were reconstructed using both mono- and bisegment algorithms. The temporal resolution was 82 milliseconds for mono- and 42 to 83 milliseconds (58 +/- 14 milliseconds) for bisegment reconstruction, the latter depending on the HR during CTCA. Images were reconstructed in the reconstruction phase having least motion artifacts in the individual patient, primarily during mid-diastole at 70% of the R-R interval. The HR variability was defined as the standard deviation from the average HR. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1: excellent to 4: nonevaluable). Effective radiation dose estimates were calculated. RESULTS: The overall image quality showed no significant differences between the 2 groups scanned with a fixed or a HR-adapted pitch (group A, score 1.21 +/- 0.63; group B, score 1.19 +/- 0.52). The overall image quality was superior when using monosegment (group A and B, score 1.21 +/- 0.63 and 1.19 +/- 0.52, respectively) when compared with the bisegment reconstruction algorithm (group B, score 1.33 +/- 0.72; P < 0.01). Image quality did not significantly correlate with average HR neither for monosegment (group A: r = 0.07; P = 0.35; group B: r = 0.06; P = 0.41) nor bisegment reconstructions (r = 0.07; P = 0.32). There was no significant correlation between image quality and HR variability using monosegment reconstructions (group A: r = 0.09; P = 0.22; group B: r = 0.05; P = 0.67), whereas a significant correlation was found for bisegment reconstructions (group B: r = 0.51; P < 0.01). The estimated effective radiation dose was significantly higher in group B (10.8 +/- 1.4 mSv) when compared with group A (9.0 +/- 0.8 mSv; P < 0.01). CONCLUSIONS: Although providing a higher temporal resolution at certain HRs, the use of bisegment reconstructions for dual-source CTCA does not result in an improved overall image quality when compared with the monosegment reconstruction algorithm.