Time-spatial Labeling Inversion Pulse Technique Research Articles

Non-contrast MR portography using time-spatial labeling inversion pulse for diagnosis of portal vein pathology

BackgroundTo study the ability of non-contrast MR portography using time-spatial labeling inversion pulse (T-SLIP) as a non-invasive contrast-free imaging modality to delineate different portal vein pathological conditions.The study included 25 patients with known history of portal vein disease and another 25 age-matched patients with normal portal vein. Both groups were examined by respiratory-triggered non-contrast MR portography using time-spatial labeling inversion pulse technique. Image quality was assessed first, and findings of diagnostic scans were compared to color duplex ultrasonography and selectively in those with diseased portal vein to portal-phase images of dynamic contrast-enhanced MRI.ResultsSignificant relation was found between breathing regularity and image quality in T-SLIP sequence, with diagnostic scans sensitivity and specificity of 89.29% and 86.21%, respectively, for diagnosis of different portal vein pathological conditions.ConclusionsNon-contrast MR portography is a useful technique for diagnosis of portal vein pathology in carefully selected patients.

Quantification of the salivary volume flow rate in the parotid duct using the time-spatial labeling inversion pulse (Time-SLIP) technique at MRI: A feasibility study.

We developed a method to quantify the volume flow rate (VFR) using the time-spatial labeling inversion pulse (Time-SLIP) technique to evaluate salivary function. To investigate the accuracy of quantification of the salivary VFR using the Time-SLIP technique in phantoms and to examine the feasibility of its use in human subjects. This was a prospective phantom and volunteer study. A phantom and 23 normal volunteers who fasted at least 2 hours study was performed. Flow images of the phantom and the parotid duct of 23 volunteers were acquired on a 3T-MRI scanner using the Time-SLIP technique. Hypothesizing that flow aggregates in the conducting duct, we measured the VFR on flow images. In the phantom study, the actual VFR (slow, medium, fast flow) was controlled by an automatic pump system and the measured VFR was compared with the actual VFR on flow images. In the human study we injected citric acid into the mouth of healthy volunteers to stimulate saliva secretion and recorded the VFR. As this study was a feasibility study, statistical tests were not performed. In the phantom study, the VFR at slow, medium, and fast flow was 5.7 ± 0.4 (SD), 8.4 ± 0.3, and 12.2 ± 1.1 mm3 /sec, respectively. The error between the measured and actual VFR values was 2.8-3.7%. Salivary flow in the parotid duct was visualized in 22 of the 23 volunteers. The mean VFR was 8760 mm3 /10 min. When salivary flow was stimulated with citric acid in normal volunteers, the salivary VFR could be obtained using the Time-SLIP technique. 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:928-935.

Non-contrast myocardial perfusion using a novel 4D magnetic resonance arterial spin labeling technique: Initial experience

The aim of this study is to develop a novel non-contrast 4-dimensional MR arterial spin labeling (4D-ASL) technique (3D acquisition and time) and to investigate myocardial perfusion on healthy volunteers without administration of contrast materials.A non-contrast 4D-ASL technique was developed using the time-spatial labeling inversion pulse (Time-SLIP) to obtain myocardium perfusion of eight volunteers at 1.5T. The tagging slab was placed on the proximal ascending aorta to invert the blood magnetization and mid-ventricle 3D images at diastolic phase were acquired with multiple tagging delays. The time resolved 3D images with various inversion times (TI) were registered and segmented for the visualization of myocardial signal changes along the TI, and perfusion curves were generated to identify the perfusion peaks.Blood flow from basal to apical slices was observed in all volunteers. Peak flow at the mid-ventricle was observed 200–400ms after the blood was tagged at the aortic root blood. After the perfusion peak, all signals returned to the base line.The 4D Time-SLIP technique permits non-contrast perfusion images with high temporal resolution, which may potentially differentiate normal from diseased myocardium.

Automated flow quantification for spin labeling MR imaging

The Time-Spatial Labeling Inversion Pulse (Time-SLIP) technique enables tracing of regional fluid flows without the use of contrast medium. The objective of this study is to quantify automatically slow and complex fluid flows using the Time-SLIP technique. Series images were acquired with a 1.5-T MRI scanner using the Time-SLIP technique with half-Fourier fast spin-echo (FSE) and balanced steady-state free precession (bSSFP) sequences. In this method, labeled fluid regions in images were automatically detected based on image processing techniques for a given point. The flow velocity of the labeled fluid region was calculated using regression fitting for the region's position. To evaluate our method, constant and non-constant laminar flows in a water phantom were studied. In addition, volunteer experiments were conducted to quantify the flow of cerebrospinal fluid. In the constant flow experiments the correlation factor r (2) between the flow velocity calculated from our method and the laminar peak velocity calculated from the volumetric flow rate was 0.9992 for the FSE sequence and 0.9982 for the bSSFP sequence. In the non-constant flow study, the flow velocity was calculated accurately for any period inversion time even when the flow velocity was changed, and the quantification error was negligible. In the volunteer experiments, r (2) between the flow velocity calculated by the proposed method and that obtained by manual annotation was 0.9383. The experimental results showed that our proposed method can quickly and accurately provide information on flow velocities especially for slower and complex flows. Our method is, therefore, expected to be useful in diagnostic support systems.