I-Chan Chiang

Objective: To determine the frequencies of fat-water swaps in iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) water-only images of the postinstrumentation spine and discuss the efficiency of in-phase imaging in improving visibility of the thecal sac.Materials and Methods: A total of 276 patients (167 women; mean age, 62.3 years; range, 23–89 years) with metallic devices on the lumbar spine who received complete routine 1.5 T MR imaging, including axial and sagittal images of T1-weighted, T2-weighted, and T2-weighted IDEAL sequences, were included. The exclusion criteria were significant motion artifacts and severe metallic artifacts in any one of the sequences. The images were reviewed by two radiologists to identify fat-water swaps that were divided into 3 groups: extraspinal swaps, intraspinal swaps in sagittal images, and intraspinal swaps in axial images. The qualitative evaluations for the spinal canal in axial images were performed by rating on a five-point scale. Side-by-side comparisons of T2-weighted images and IDEAL in-phase images were also performed.Results: In patient-based data of 276 patients, extraspinal fat-water swaps were noted in 10 patients (3.6%) and intraspinal swaps were noted in 160 patients (58.0%). The intraspinal swaps had a higher incidence in the patients with more levels of metallic devices with screws and the trend was not noted in the extraspinal swaps. A total of 928 axial levels were evaluated in the level-based data of axial images. T1-weighted, T2-weighted, and IDEAL in-phase images had significantly better imaging quality than the IDEAL water-only images (3.9 ± 0.4, 3.9 ± 0.3, 3.8 ± 0.4 vs 3.0 ± 1.3, allP< 0.001). Compared with T2-weighted images, most of the IDEAL in-phase images (reader 1, 90.9%; reader 2, 86.7%) present similar quality.Conclusion: Iterative decomposition of water and fat with echo asymmetry and least-squares estimation sequence can provide good fat suppression in most spine MRI with metallic devices but the loss of cerebrospinal fluid signal intensities due to fat-water swaps are noted in more than half of postinstrumentation spine. Routine reconstruction of in-phase images is recommended to improve evaluation of the thecal sac by avoiding pitfall caused by fat-water swaps.

Objective:Carotid blow-out syndrome (CBS) is a life-threatening complication of head and neck cancer (HNC). One of the various methods used for emergency management of CBS is covered stent placement (CSP). Our initial experience in CSP is evaluated and compared with reports in the literature.Methods:This study analysed 17 patients with HNC who had received CSP for CBS at Kaohsiung Medical University Chung-Ho Memorial Hospital from May 2005 to December 2013. The medical records and images for these patients were retrospectively reviewed to evaluate the causes of CBS, treatment success rates and complications.Results:The initial angiography success rate was 100%. Procedural or periprocedural complications were noted in two (12%) cases, both suffering from cerebral vascular accident (CVA). Short-term complications were noted in eight (47%) cases, including four rebleeding cases and four CVA cases. Medium- to long-term complications were noted in nine cases, which included two asymptomatic in-stent thrombosis...

This study compared the effectiveness of relative cerebral blood volume, apparent diffusion coefficient, and spectroscopic imaging in differentiating between primary high-grade gliomas and solitary metastases. A 3.0-T MR unit was used to perform proton MR spectroscopy, diffusion imaging, and conventional MR imaging on 26 patients who had solitary brain tumors (14 high-grade gliomas and 12 metastases). All diagnoses were confirmed by biopsy. Twelve perfusion MR studies (8 high-grade gliomas and 4 metastases) were also performed. The results showed that the choline to creatine ratio and relative cerebral blood volume in the peritumoral regions of high-grade gliomas were significantly higher than they were in the metastases. The apparent diffusion coefficient values in tumoral and peritumoral regions of metastases were significantly higher than they were in the primary gliomas. Although conventional MR imaging characteristics of solitary metastases and primary high-grade gliomas may sometimes be similar, the peritumoral perfusion-weighted and spectroscopic MR imaging enable distinction between the two. Diffusion-weighted imaging techniques were complementary techniques to make a differential diagnosis between the two malignant tumors.