scholarly journals SCALE-PWI: A Pulse Sequence for Absolute Quantitative Cerebral Perfusion Imaging

2010 ◽  
Vol 31 (5) ◽  
pp. 1272-1282 ◽  
Author(s):  
Jessy Mouannes Srour ◽  
Wanyong Shin ◽  
Saurabh Shah ◽  
Anindya Sen ◽  
Timothy J Carroll
Keyword(s):  
Image Reconstruction ◽  
Cerebral Perfusion ◽  
Cerebral Blood Volume ◽  
Pulse Sequence ◽  
Patient Specific ◽  
Dynamic Susceptibility ◽  
Single Shot ◽  
Planar Imaging ◽  
Perfusion Image ◽  
Scan Time

The Bookend technique is a magnetic resonance imaging (MRI) dynamic susceptibility contrast method that provides reliable quantitative measurement of cerebral blood flow (CBF) and cerebral blood volume (CBV). The quantification is patient specific, is derived from a steady-state measurement of CBV, and is obtained from T1 changes in the white matter and the blood pool after contrast agent injection. In the current implementation, the Bookend technique consists of three scanning steps requiring a cumulative scan time of 3minutes 47seconds, a well-trained technologist, and extra time for offline image reconstruction. We present an automation and acceleration of the multiscan Bookend protocol through a self-calibrating pulse sequence, namely Self-Calibrated Epi Perfusion-Weighted Imaging (SCALE-PWI). The SCALE-PWI is a single-shot echo-planar imaging pulse sequence with three modules and a total scan time of under 2minutes. It provides the possibility of performing online, quantitative perfusion image reconstruction, which reduces the latency to obtain quantitative maps. A validation study in healthy volunteers ( N = 19) showed excellent agreement between SCALE-PWI and the conventional Bookend protocol ( P > 0.05 with Student's t-test, r = 0.95/slope = 0.98 for quantitative CBF, and r = 0.91/slope = 0.94 for quantitative CBV). A single MRI pulse sequence for absolute quantification of cerebral perfusion has been developed.

scholarly journals Multimodal MRI Features of Medulloblastoma with Extensive Nodularity and Activated Sonic Hedgehog: A Case Report

2021 ◽  
Vol 18 (2) ◽  
Author(s):  
Jihyun Kim ◽  
Byung Hyun Baek ◽  
Yun Young Lee ◽  
Woong Yoon ◽  
Kyung-Hwa Lee ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Cerebral Blood Volume ◽  
Autologous Blood ◽  
Tumor Resection ◽  
Dynamic Susceptibility ◽  
Dynamic Susceptibility Contrast ◽  
Mri Findings ◽  
Perfusion Image ◽  
Diffusion Weighted Images ◽  
Mri Features

: Medulloblastoma with extensive nodularity (MBEN) is a rare histological subtype of medulloblastomas in very young children. It is characterized by an aggressive grape-like appearance and favorable outcomes. Herein, we report the case of a nine-month-old patient with MBEN, associated with an activated sonic hedgehog (SHH), with rare multimodal magnetic resonance imaging (MRI) features. Conventional MRI findings indicated the dense homogeneous enhancement of a large unusual gyriform mass in the cerebellar vermis and both cerebellar hemispheres. The mass showed restricted diffusion on diffusion-weighted images, low concentrations of taurine on MR spectroscopy, and a relatively low cerebral blood volume on dynamic susceptibility contrast (DSC) MR perfusion image. The patient underwent partial tumor resection, chemotherapy, and autologous blood stem cell transplantation. After treatment, the lesion rapidly regressed in the serial follow-up imaging without recurrence.

scholarly journals NIMG-28. VALIDATION OF SINGLE-DOSE DSC-MRI PROTOCOLS FOR ROBUST PERFUSION ASSESSMENT IN BRAIN TUMORS

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi167-vi167
Author(s):  
Chad Quarles ◽  
Laura Bell ◽  
Natenael Semmineh ◽  
Alberto Fuentes ◽  
Melissa Prah ◽  
...  
Keyword(s):  
Single Dose ◽  
Contrast Agent ◽  
Cerebral Blood Volume ◽  
Bolus Injection ◽  
Pulse Sequence ◽  
Flip Angle ◽  
Response To Treatment ◽  
Dynamic Susceptibility ◽  
Double Dose ◽  
Dsc Mri

Abstract Dynamic susceptibility contrast (DSC) MRI measures of brain tumor cerebral blood volume (CBV) are able to predict grade, overall survival and response to treatment. Wide-spread acceptance of DSC-MRI has been challenged by the need to balance contrast agent dose and CBV accuracy. The goal of this study was to identify and validate single-dose, BTIP compliant, DSC-MRI protocols. Using a validated, patient-based DRO, we evaluated CBV accuracy across a range of acquisition parameters (field strength, TR, TE, flip angle, multi-echo acquisitions, dosing protocols) and post-processing steps. To validate the optimal protocols, we next collected DSC-MRI data following ASFNR’s recommended “double – dose” approach, where a single-dose preload (to minimize T1 effects) is given prior to a second bolus injection (for DSC-MRI data acquisition). The single-dose DSC-MRI data was collected during the preload bolus injection. Consistency of the derived CBV data, visual agreement and data characteristics (e.g. CNR) was statistically evaluated. When using a single-dose and routine single-echo pulse sequence, the DRO analysis found that a low flip angle (LFA = 30o) and 30ms TE provided the highest CBV accuracy (concordance correlation coefficient (CCC) = 0.92) and precision (coefficient of variation (CV) = 8.2%)). For comparison, the maximum accuracy found with the DRO utilizes a double-dose injection protocol and yielded a CCC of 0.98 and CV of 6.8%. Single-dose, multi-echo acquisitions provided higher accuracy than the LFA data and matched that found with the double-dose approach. In patients (data collection ongoing), the agreement between single-dose LFA (n > 40) or multi-echo (n > 40) based CBV values and the reference double-dose approach was very high (CCC > 0.94) and were statistically equivalent. Optimized single-dose DSC-MRI protocols provide highly accurate CBV data, use lower doses of contrast agent, and simplify scan procedures, indicating their potential for robust use in clinical practice and trials.

scholarly journals Slice-direction geometric distortion evaluation and correction with reversed slice-select gradient acquisitions

2021 ◽  
Author(s):  
Anna I Blazejewska ◽  
Thomas Witzel ◽  
Jesper LR Andersson ◽  
Lawrence L Wlad ◽  
Jonathan R Polimeni
Keyword(s):  
High Resolution ◽  
Strong Field ◽  
Pulse Sequence ◽  
Geometric Distortion ◽  
Single Shot ◽  
Planar Imaging ◽  
Phase Encoding ◽  
Spatial Alignment ◽  
Ultrahigh Field Mri ◽  
Echo Planar

Accurate spatial alignment of MRI data acquired across multiple contrasts in the same subject is often crucial for data analysis and interpretation, but can be challenging in the presence of geometric distortions that differ between acquisitions. It is well known that single-shot echo-planar imaging (EPI) acquisitions suffer from distortion in the phase-encoding direction due to B0 field inhomogeneities arising from tissue magnetic susceptibility differences and other sources, however there can be distortion in other encoding directions as well in the presence of strong field homogeneities. High-resolution ultrahigh-field MRI typically uses low bandwidth in the slice-encoding direction to acquire thin slices and, when combined with the pronounced B0 inhomogeneities, is prone to an additional geometric distortion in the slice direction as well. Here we demonstrate a presence of this slice distortion in high-resolution 7T EPI acquired with a novel pulse sequence allowing for the reversal of the slice-encoding gradient polarity that enables the acquisition of pairs of images with equal magnitudes of distortion in the slice direction but with opposing polarities. We also show that the slice-direction distortion can be corrected using gradient reversal-based method applying the same software used for conventional corrections of phase-encoding direction distortion.

scholarly journals Advances in Spiral fMRI: A High-resolution Study with Single-shot Acquisition

2019 ◽  
Author(s):  
Lars Kasper ◽  
Maria Engel ◽  
Jakob Heinzle ◽  
Matthias Mueller-Schrader ◽  
Nadine N. Graedel ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Static Field ◽  
7 Tesla ◽  
List Type ◽  
Single Shot ◽  
Planar Imaging ◽  
Spatiotemporal Resolution ◽  
Signal Model ◽  
Spiral Imaging ◽  
Spiral Readout

AbstractSpiral fMRI has been put forward as a viable alternative to rectilinear echo-planar imaging, in particular due to its enhanced average k-space speed and thus high acquisition efficiency. This renders spirals attractive for contemporary fMRI applications that require high spatiotemporal resolution, such as laminar or columnar fMRI. However, in practice, spiral fMRI is typically hampered by its reduced robustness and ensuing blurring artifacts, which arise from imperfections in both static and dynamic magnetic fields.Recently, these limitations have been overcome by the concerted application of an expanded signal model that accounts for such field imperfections, and its inversion by iterative image reconstruction. In the challenging ultra-high field environment of 7 Tesla, where field inhomogeneity effects are aggravated, both multi-shot and single-shot 2D spiral imaging at sub-millimeter resolution was demonstrated with high depiction quality and anatomical congruency.In this work, we further these advances towards a time series application of spiral readouts, namely, single-shot spiral BOLD fMRI at 0.8 mm in-plane resolution. We demonstrate that spiral fMRI at 7 T is not only feasible, but delivers both competitive image quality and BOLD sensitivity, with a spatial specificity of the activation maps that is not compromised by artifactual blurring. Furthermore, we show the versatility of the approach with a combined in/out spiral readout at a more typical resolution (1.5 mm), where the high acquisition efficiency allows to acquire two images per shot for improved sensitivity by echo combination.HighlightsThis work reports the first fMRI study at 7T with spiral readout gradient waveforms.We achieve spiral fMRI with sub-millimeter resolution (0.8 mm, in-plane FOV 230 mm), acquired in a single shot.Spiral images exhibit intrinsic geometric congruency to anatomical scans, and spatially highly specific activation patterns.Image reconstruction rests on a signal model expanded by measured trajectories and static field maps, inverted by cg-SENSE.We assess generalizability of the approach for spiral in/out readouts, providing two images per shot (1.5 mm resolution).

scholarly journals Improved image reconstruction for partial fourier gradient-echo echo-planar imaging (EPI)

2008 ◽  
Vol 59 (4) ◽  
pp. 916-924 ◽  
Author(s):  
Nan-kuei Chen ◽  
Koichi Oshio ◽  
Lawrence P. Panych
Keyword(s):  
Image Reconstruction ◽  
Echo Planar Imaging ◽  
Gradient Echo ◽  
Planar Imaging ◽  
Echo Planar
Sign in / Sign up

Export Citation Format

Share Document