A radiation exposure index for CT

Evaluation of the computer-assisted virtual surgical technology in preoperative planning for distal femoral fracture

BACKGROUND

The application of computer-assisted virtual surgical technology in preoperative planning for distal femoral fractures has been rarely presented. This study aimed to evaluate the intra-operative realization of this technology and the clinical outcomes based on it for distal femoral fractures.

METHODS

Between February 2014 and May 2017, 32 patients with distal femoral fractures treated by open reduction and internal fixation were included and divided into 2 groups on the basis of preoperative planning methods: conventional (N = 17) and virtual surgical (N = 15). The time required for virtual segmentation, reduction, and fixation of the fracture fragments in virtual surgical group were analyzed. Operation time, intra-operative blood loss, times of fluoroscopy during operation and days of hospital stay in two groups were compared. Postoperative functional outcomes were assessed using the Knee Society Score (KSS), Short Form-36 (SF-36) scoring systems, and visual analogue scale (VAS) for pain.

RESULTS

Mean total planning time for 33-A, 33-B, and 33-C fractures in virtual surgical group were 43.0 ± 1.7, 23.0 ± 1.3, and 51.4 ± 3.7 min, respectively. Compared with the conventional group, Patients in virtual surgical group had lower blood loss, fewer fluoroscopic images, less operative time, and shorter days of hospital stay (P < 0.05). No significant difference could detected in the KSS, SF-36, or VAS scores between the two groups at the final follow-up (P > 0.05).

CONCLUSIONS

Computer-assisted virtual surgical technology could rapidly complete surgical treatment protocol, improve operative efficiency, and provide satisfying clinical and radiographic outcomes for distal femoral fractures.

Reaching for better image quality and lower radiation dose in head and neck CT: advanced modeled and sinogram-affirmed iterative reconstruction in combination with tube voltage adaptation

OBJECTIVES

The aim of this study was to evaluate image quality and radiation dose in low-dose head and neck CT comparing two different commercially available iterative reconstruction algorithms: sinogram-affirmed iterative reconstruction (SAFIRE) and advanced modeled iterative reconstruction (ADMIRE) with fixed and automated tube voltage adaptation (TVA).

METHODS

CT examinations of 103 patients were analysed. 58 patients were examined on a single-source CT at fixed tube voltage of 120 kV and reconstructed with filtered back projection (FBP) and SAFIRE (Strength Level 3). 45 patients were examined in a single-source mode on a dual-source CT with automated TVA and reconstructed with FBP and ADMIRE (Strength Levels 2 and 3). Image noise was calculated in seven anatomical volumes of interest. Subjective evaluation of the CT images was performed using a four-grade scale.

RESULTS

Mean CT numbers of FBP and the corresponding iterative reconstruction did not differ significantly (p = 0.74-0.99). Image noise was lower with both iterative reconstruction techniques than with FBP (SAFIRE 3: -22.3%; ADMIRE 2: -14.9%; ADMIRE 3: -24.2%; all p < 0.05); hence, the signal-to-noise ratio and the contrast-to-noise values were higher. Subjective image quality revealed a more favourable result for the iterative reconstruction. ADMIRE 3 in combination with automated TVA showed 14.4% (p < 0.05) less image noise with a 7.5% lower radiation dose than SAFIRE 3 with fixed tube voltage.

CONCLUSIONS

Higher image quality at lower radiation dose can be achieved using ADMIRE in combination with automated TVA.

A reliable radiographic measurement for evaluation of normal distal tibiofibular syndesmosis: a multi-detector computed tomography study in adults

Background

Syndesmotic injury may be difficult to diagnose, and radiological evaluation is very important. The purpose of this study was to offer a series of reliable and repeatable normal tibiofibular syndesmosis parameters in diagnosing injuries of the syndesmosis.

Methods

Multi-detector computed tomography (MDCT) and radiographs of the distal tibiofibular syndesmosis in 484 cases were retrospectively reviewed. Relevant parameters included the tibiofibular clear space (TCS), the tibiofibular overlap (TFO), the depth of the incisura fibularis (IFD), and the height of the incisura fibularis (IFH), which were measured by novel three-dimensional (3-D) and two-dimensional (2-D) techniques. The distance between the measuring plane of the distal tibiofibular syndesmosis and the tibial plafond was measured. Intra- and inter-rater reliability was assessed by intraclass correlation coefficient (ICC) and the root mean square standard deviation (RMS-SD), to determine measurement precision. Sex differences of parameters were analyzed using analysis of covariance (ANCOVA) with body height as the covariate. Paired sample t-testing was used to compare parameters in different image modalities, including radiography, and 2-D and 3-D CT.

Results

The reliability of the 3-D images measurement (ICC range, 0.907 to 0.972) was greater than that for the 2-D axial images (ICC range, 0.895 to 0.927), and the AP view radiographs (ICC range, 0.742 to 0.838). The intra-rater RMS-SD of the 3-D CT, 2-D CT and radiographic measurements were less than 0.94 mm, 0.26 mm, and 2.87 mm, respectively. The measuring plane of the distal tibiofibular syndesmosis showed the sex difference, which was 12.1 mm proximal to the tibial plafond in the male group and 7.8 mm in the female group. In this plane, the parameters for tibiofibular syndesmosis were measured in different image modalities. All variables were significantly different between females and males (p < 0.05).

Conclusions

3-D measurement technique could be helpful to identify the precise measurement planes for syndesmosis, which were not at the fixed level above the tibial plafond because of the sex difference. In this plane, reliable measurement results could be provided, in either 2-D or 3-D MDCT images.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-015-0093-6) contains supplementary material, which is available to authorized users.