Chien Kuo Wang

Accurate central venous port-A catheter placement: intravenous electrocardiography and surface landmark techniques compared by using transesophageal echocardiography.

Using transesophageal echocardiography (TEE) to locate the tip of central venous catheters inserted via the right subclavian vein, we compared IV electrocardiography (IV-ECG)-guided catheter tip placement with the conventional surface landmark technique. Sixty patients were randomly assigned into two groups. In Group E, the IV-ECG signal was conducted along an NaHCO3-filled catheter to facilitate catheter placement. In Group S, surface landmarks on the chest wall were used to determine the appropriate catheter length. The goal was to visualize the catheter tip with TEE at the superior edge of the crista terminalis, which is the junction of the superior vena cava (SVC) and right atrium (RA). The catheter tip position was considered to be satisfactory, as the tip was within 1.0 cm of the upper crista terminalis edge. All 30 Group E patients had satisfactory catheter tip placement when the ECG P wave was at its maximum. In contrast, 16 of the 30 patients in Group S had satisfactory tip positions (P < 0.001). All catheters were repositioned under TEE guidance to adjust the tip to the SVC-RA junction. After the catheter tips were confirmed to be located at the SVC-RA junction, the catheter tips were still visualized in the mid portion of RA in 12 of 60 patients on supine chest radiographs. We concluded that IV-ECG guidance to position a catheter resulted in satisfactory catheter tip placement that is in accordance with TEE views. Catheter placement at the SVC-RA junction with the surface landmark technique was unreliable.

Bone Marrow Edema in Vertebral Compression Fractures: Detection with Dual-Energy CT

PURPOSE To assess the use of the dual-energy computed tomographic (CT) virtual noncalcium technique in the evaluation of bone marrow edema in vertebral compression fractures. MATERIALS AND METHODS This prospective study was approved by the institutional review board; informed consent was obtained from all patients. Sixty-three consecutive patients with 112 thoracic and/or lumbar vertebral compression fractures were studied between January 2011 and April 2012. All patients underwent both dual-energy CT (100 kV and Sn140 kV, where Sn indicates the use of a 0.4-mm tin filter) and magnetic resonance (MR) imaging. Dual-energy CT data were postprocessed by using a three-material decomposition algorithm for generating noncalcium images of the collapsed bodies. Two radiologists evaluated for the presence of abnormal attenuation alterations in the bone marrow by using color-coded maps and measured CT numbers on noncalcium grayscale images. Bone sclerosis and intravertebral air were evaluated with CT scans. MR images served as the reference standard. CT numbers were subjected to receiver operating characteristic curve analysis. RESULTS MR imaging depicted 46 edematous and 66 nonedematous vertebral compression fractures. Eighty-two bodies were classified as having less than 50% sclerosis and/or air. Significant differences in noncalcium CT numbers between edematous and nonedematous vertebral compression fractures were found for both readers (P < .0001). CT numbers for the diagnosis of bone marrow edema on the basis of MR imaging revealed areas under the receiver operating characteristic curve of 0.799 and 0.841 for readers 1 and 2, respectively (P = .56). Use of a cutoff value of -80 to differentiate edematous vertebral bodies resulted in a sensitivity of 96.3%, specificity of 98.2%, and accuracy of 97.6% in the group of vertebral bodies with less than 50% sclerosis and/or air. CONCLUSION Dual-energy CT virtual noncalcium images were able to depict bone marrow in the collapsed vertebral bodies, especially in those with less than 50% sclerosis and/or air.

Comparison of radiographic landmarks and the echocardiographic SVC/RA junction in the positioning of long-term central venous catheters

Background:  When implanting a permanent central venous catheter, the usual aim is to place the tip at the superior vena cava/right atrial (SVC/RA) junction. However, data validating radiographic landmarks of the SVC/RA junction are limited. This investigation was undertaken to compare the radiographic landmarks with the SVC/RA junction as determined by transesophageal echocardiography (TEE).

Carpal tunnel syndrome assessed with diffusion tensor imaging: Comparison with electrophysiological studies of patients and healthy volunteers

The main goal of this study was to investigate the applicability of parameters derived from diffusion tension imaging (DTI) in diagnosing carpal tunnel syndrome (CTS). Forty subjects were recruited, of which 19 were normal controls and 21 belonged to the CTS group. DTI of median nerves evaluated at 4 levels of the wrist (distal radius, pisiform bone, middle portion of the carpal tunnel, and hamate bone) and conventional MRI of the wrist was performed in normal and CTS subjects in two finger postures (extension and flexion). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were derived from DTI, and parameters related to abnormal hyperintensity of the median nerve were derived from conventional MRI. Electrophysiological tests, including nerve conduction velocity and F wave were also performed for comparison. The results of FA and ADC measurements did not depend on the measuring location and finger posture. Mean FA was decreased while mean ADC was increased by CTS. FA and ADC at the middle portion of the carpal tunnel was 0.47±0.05 and 1.37±0.12 (×10(-3) mm2/s) for the control group and 0.42±0.04 and 1.50±0.15 (×10(-3) mm2/s) for the CTS group, respectively. The linear correlations of FA and ADC versus electrophysiological indicators of CTS were significant (R2 ranged from 0.09 to 0.36), indicating FA and ADC from DTI had significant correlation with the existence and severity of CTS.

MR grading system of osteochondritis dissecans lesions: Comparison with arthroscopy

OBJECTIVE To assess the diagnostic performance of combined three-dimensional (3D) gradient-echo (GRE) T1-weighted and routine MR imaging protocol for the evaluation of osteochondritis dissecans (OCD). MATERIALS AND METHODS This prospective study was approved by our institutional review board and all patients gave informed consent. Three-dimensional GRE MR sequence was added to the routine protocol performed on 40 consecutive patients (35 men, 5 women; age range, 12-57 years; mean age, 20 years) with 17 juvenile and 24 adult OCD lesions (27 in knees; 14 in elbows) which were confirmed by arthroscopy. Two independent musculoskeletal radiologists reviewed all MR images. The OCD lesions were classified into five stages by assessing the signal intensity of fragment-bone interface and the integrity of articular cartilage on MR images. Stage-IV and -V lesions were considered as unstable. The sensitivity, specificity, accuracy, and interobserver agreement (κ statistics) were calculated. RESULTS The sensitivity, specificity, and accuracy for detection of OCD instability were 100% (11 of 11), 100% (6 of 6), and 100% (17 of 17) in juvenile lesions; and 93% (14 of 15), 100% (9 of 9), and 96% (23 of 24) in adult lesions. The overall accuracy of MR findings in determining the staging was 90% (37 of 41) for reader 1 and 83% (34 of 41) for reader 2. Agreement between readers was substantial with a κ value of 0.75 for MR staging of OCD lesions. CONCLUSIONS Three-dimensional GRE T1-weighted MR imaging combined with the routine sequences demonstrates excellent diagnostic capabilities in detecting unstable OCD lesions.

MRI appearance of giant cell tumor of the lateral skull base:A case report

The giant cell tumor is considered to be a locally aggressive benign tumor and has a low tendency toward distant metastasis. They are primarily present in the long bone and are rare in the skull. The osteoclast-like giant cells do not demonstrate mitotic activity and contain large numbers of nuclei. Herein, we described a case of giant cell tumor in the temporal lobe. Heterogenous enhancement is shown on CT imaging in solid areas of tumor. The appearance intermediate to high signal intensity on T1-weighted and very low signal intensity on T2-weighted MR imaging were due to the presence of hemosiderin from prior hemorrhage.

Dynamic Contrast-Enhanced Subtraction and Delayed MRI of Gastric Tumors: Radiologic-Pathologic Correlation

Purpose Our goal was to determine whether dynamic MR subtraction images could be used to detect and stage gastric tumors. Method Dynamic MR subtraction images were prospectively performed in 20 patients without gastric lesions and in 39 patients with gastric tumors. The flat-or depressed-type early gastric cancers were excluded. The MR findings were assessed for layered pattern of the normal gastric wall, detectability of tumors, enhanced pattern of tumor, and depth of the tumor invasion. Surgical specimens were obtained from 30 of the patients with tumors, and histopathologic sections were made in the dynamic MR scanning direction. Results The three-layered structure of the normal gastric wall was apparent in more of the dynamic MR subtraction images (60%) than of the nonsubtraction images (30%) in the control group. All 39 gastric tumors were detected by MRI. The intact inner layers overlying stromal tumors and outer layers interrupted by advanced gastric cancers were clear on the subtracted images. MRI accurately T-staged 88% of the gastric cancers. Conclusion Dynamic MR subtraction images can be used to identify gastric tumors and to stage gastric cancers.

Differentiating Radiation-Induced Necrosis from Recurrent Brain Tumor Using MR Perfusion and Spectroscopy: A Meta-Analysis.

Purpose This meta-analysis examined roles of several metabolites in differentiating recurrent tumor from necrosis in patients with brain tumors using MR perfusion and spectroscopy. Methods Medline, Cochrane, EMBASE, and Google Scholar were searched for studies using perfusion MRI and/or MR spectroscopy published up to March 4, 2015 which differentiated between recurrent tumor vs. necrosis in patients with primary brain tumors or brain metastasis. Only two-armed, prospective or retrospective studies were included. A meta-analysis was performed on the difference in relative cerebral blood volume (rCBV), ratios of choline/creatine (Cho/Cr) and/or choline/N-acetyl aspartate (Cho/NAA) between participants undergoing MRI evaluation. A χ2-based test of homogeneity was performed using Cochran’s Q statistic and I2. Results Of 397 patients in 13 studies who were analyzed, the majority had tumor recurrence. As there was evidence of heterogeneity among 10 of the studies which used rCBV for evaluation (Q statistic = 31.634, I2 = 97.11%, P < 0.0001) a random-effects analysis was applied. The pooled difference in means (2.18, 95%CI = 0.85 to 3.50) indicated that the average rCBV in a contrast-enhancing lesion was significantly higher in tumor recurrence compared with radiation injury (P = 0.001). Based on a fixed-effect model of analysis encompassing the six studies which used Cho/Cr ratios for evaluation (Q statistic = 8.388, I2 = 40.39%, P = 0.137), the pooled difference in means (0.77, 95%CI = 0.57 to 0.98) of the average Cho/Cr ratio was significantly higher in tumor recurrence than in tumor necrosis (P = 0.001). There was significant difference in ratios of Cho to NAA between recurrent tumor and necrosis (1.02, 95%CI = 0.03 to 2.00, P = 0.044). Conclusions MR spectroscopy and MR perfusion using Cho/NAA and Cho/Cr ratios and rCBV may increase the accuracy of differentiating necrosis from recurrent tumor in patients with primary brain tumors or metastases.

MRI of multifocal kaposiform haemangioendothelioma without Kasabach–Merritt phenomenon

Kaposiform haemangioendothelioma is a rare soft-tissue tumour of infants and children, and presents as a moderately aggressive malignancy. We present the MRI findings of a histologically proven case of Kaposiform haemangioendothelioma without Kasabach-Merritt phenomenon or typical skin changes. Our case also reveals that the multiple foci of the cutaneous tumour have different MRI morphologies. These findings have not been reported in the literature to date.

Longitudinally monitoring chemotherapy effect of malignant musculoskeletal tumors with in vivo proton magnetic resonance spectroscopy: an initial experience.

Purpose: To investigate the value of in vivo proton (1H) magnetic resonance spectroscopy (MRS) in longitudinally monitoring the treatment response of malignant musculoskeletal tumors under chemotherapy. Materials and Methods: Twenty-three studies in 3 patients with bone and soft-tissue tumors (2 lymphomas and 1 alveolar soft part sarcoma) were included in the study. The dynamic contrast-enhanced magnetic resonance (MR) imaging and single-voxel proton MRS with 135 milliseconds of echo time were carried out using a whole-body 1.5-T scanner and a surface coil. The volume of interest within the lesion was positioned on the area of early enhancement according to the finding of the first dynamic contrast-enhanced MR imaging with subtraction. The choline and water intensities were measured at the peak areas at 3.2 and 4.5 ppm. The choline-water ratios were calculated as well. Statistical analysis was performed by using Kruskal-Wallis 1-way analysis of variance test (Table 1). TABLE 1. Summary of MRS Findings of the 23 Follow-Up Studies in the 3 Patients Results The changes observed on the dynamic contrast-enhanced MR images and tumor size after chemotherapy fell into 2 clearly distinct patterns: subsequent partial response (patients 1 and 2) and progressive disease (patient 3). The choline concentration, choline-volume ratio, and choline-water ratio in the first 2 patients were reduced substantially to zero in the follow-up MRS. In the remaining patient, the choline, choline-volume ratio, and choline-water ratio remained high in the follow-up MRS. The water concentration and water-volume ratio between the 3 patients showed significant statistical differences (Kruskal-Wallis test, P = 0.004 and 0.039). Conclusion In vivo proton MRS is technically feasible for the evaluation of musculoskeletal tumors. Choline can be detected in malignant bone and soft-tissue tumors, and the early metabolite changes after chemotherapy can also be identified in the in vivo proton MRS by using a standard clinical-use 1.5-T MR scanner and a surface coil. The decline of choline after treatment in malignant bone and soft-tissue tumors correlates with the response of the dynamic contrast MR images and the tumor size. The information provided with MR imaging and proton MRS may improve the diagnostic specificity of MR examination in the follow-up of tumor treatment.