![]() Similarly, intramedullary cavity delineation was rated diagnostic or better in all cases for ZTE–CT, and ZTE–XR was at least diagnostic in 58–63% of cases. Cortical delineation was rated diagnostic or better (score of 3, 4 or 5) in all cases (confidence interval of proportions = 100%) for ZTE–CT/XR. ZTE–CT versus CT and ZTE–XR versus radiography of cortical thicknesses were not significantly different (P=0.55 and P=0.31, respectively). We calculated confidence interval of proportions, Wilcoxon rank sum test and intraclass correlation coefficients for inter-reader agreement.ResultsCohorts 1, 2 and 3 consisted of 40, 20 and 35 cases, respectively (age range 0.6−23.0 years). We measured cortical thickness of ZTE–XR and ZTE–CT and compared these with conventional imaging. Further, we made image comparisons on a 5-point scale (Scomp) (range of −2 = conventional CT/XR greater anatomical delineation to +2 = ZTE–CT/XR greater anatomical delineation 0=same) for three cohorts: (1) ZTE–XR to conventional radiography, (2) ZTE–CT to conventional CT and (3) pathological lesion assessment on ZTE–XR to conventional radiography. We assessed ZTE–CT/XR anatomical image quality (Sanat) from 0 (nondiagnostic) to 5 (outstanding). A radiograph-like image was also created with ray-sum image processing. This study investigated our institution’s initial experience in implementing an isotropic ZTE MR imaging sequence for pediatric musculoskeletal examinations.Materials and methodsPediatric patients referred for extremity MRI at 3 tesla (T) underwent ZTE MR imaging to yield images with contrast similar to that of CT. Zero echo time (ZTE) MR imaging produces a “CT-like” osseous contrast that might obviate CT.Objective ![]() Projection radiography (XR) is often supplemented by both CT (to evaluate osseous structures with ionizing radiation) and MRI (for marrow and soft-tissue assessment). On each histogram, the horizontal axis represents the signal intensity and the vertical axis represents the count. After we applied inversion logarithmic image rescaling, the CT-like contrast image reveals excellent cortical bone delineation. C, The final dataset of the CT-like contrast image with further postprocessing. B, The ZTE dataset of proton-density contrast. There are 2 typical intensity histograms and corresponding axial images. B and C, Histogram-based intensity-correction has been used to generate the CT-like bone image. Such a small gradient change results in a fast, silent scan. The readout gradients (Gx, Gy, Gz) are ramped up before the RF and change in small steps. The ZTE sequence uses a hard radiofrequency (RF) pulse and switch data acquisition (DAQ) just after the RF to receive the free induction decay signal, which results in a nominal ZTE. It also provides consistent results on the quantitative measurement of cortical bone with CT images.Ī, ZTE pulse sequence diagram of a segment with 5 spokes (the actual scan contains 384 spokes per segment). Zero TE skull MR imaging has diagnostic image quality comparable with that of CT images. 401) with high interobserver agreement (P <. The mean value of normalized bone tissue signal among the 3 layers of the skull was relatively consistent (P =. The 2 imaging modalities showed no difference in skull thickness (P =. 157), respectively, with substantial interobserver agreement (P <. The mean scores for skull MR imaging and CT were 4.65 ± 0.56 and 4.73 ± 0.45 (P =. Interobserver reliability was assessed using weighted κ statistics and the intraclass correlation coefficient.īoth imaging techniques clearly depicted skull fractures in all 13 patients. To evaluate quantitative analyses between the 2 imaging modalities, we measured skull thickness and normalized bone tissue signal. Image quality was graded on a 5-point Likert scale to compare the 2 modalities. Thirteen enrolled patients with head trauma were assessed using brain CT and skull MR imaging. The aim of this study was to investigate the clinical feasibility of skull MR imaging using the zero TE sequence in patients with head trauma by assessing its diagnostic image quality and quantitative measurement compared with CT images. Conventional MR imaging techniques cannot produce optimal images of bone structures because bone has little water and a very short T2 life span.
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