Ultra‐fast imaging using low flip angles and fids

Madio, David P.; Lowe, I. J.

doi:10.1002/mrm.1910340407

Cited by 147 publications

(147 citation statements)

References 7 publications

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“…Silenz (General Electric Healthcare) is based on a 3D gradient-echo imaging technique with a very short TE and low flip angles (5). The inherent contrast without any preparatory pulses is similar to proton density.…”

Section: Silenz Pulse Sequencementioning

confidence: 99%

Acoustic noise reduction in MRI using Silent Scan: an initial experience

Alibek¹,

Vogel²,

Sun³

et al. 2014

Diagn Interv Radiol

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PURPOSEAcoustic noise during magnetic resonance imaging (MRI) is the main source for patient discomfort and leads to verbal communication problems, difficulties in sedation, and hearing impairment. Silent Scan technology uses less changes in gradient excitation levels, which is directly related to noise levels. Here, we report our preliminary experience with this technique in neuroimaging with regard to subjective and objective noise levels and image quality. MATERIALS AND METHODS Ten patients underwent routine brain MRI with 3 TeslaMR750w system and 12-channel head coil. T1-weighted gradient echo (BRAVO) and Silenz pulse sequence (TE=0, 3D radial center-out k-space filling and data sampling with relatively small gradient steps) were performed. Patients rated subjective sound impression for both sequences on a 6-point scale. Objective sound level measurements were performed with a dedicated device in gantry at different operation modes. Image quality was subjectively assessed in consensus by two radiologists on a 3-point scale. RESULTSReaders rated image quality as fully diagnostic in all patients. Measured mean noise was reduced significantly with Silenz sequence (68.8 dB vs. 104.65 dB with BRAVO, P = 0.024) corresponding to 34.3% reduction in sound intensity and 99.97% reduction in sound pressure. No significant difference was observed between Silenz sound levels and ambient sounds (i.e., background noise in the scanner room, 68.8 dB vs. 68.73 dB, P = 0.5). The patients' subjective sound level score was lower for Silenz compared with conventional sequence (1.1 vs. 2.3, P = 0.003). CONCLUSION T1-weighted Silent Scan is a promising technique for acoustic noise reduction and improved patient comfort.

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Section: Silenz Pulse Sequencementioning

confidence: 99%

Acoustic noise reduction in MRI using Silent Scan: an initial experience

Alibek¹,

Vogel²,

Sun³

et al. 2014

Diagn Interv Radiol

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“…It already has been applied in imaging of bone samples and thermoplastic objects. 15,16 Another approach without echo time spin evolution is zero echo time (ZTE) MR. [17][18][19][20] It is closely related to UTE and has been implemented on small animal MR systems. 21 A hard RF pulse is applied to accomplish spatially nonselective excitation that covers the full frequency bandwidth spanned by the readout gradient.…”

Section: Introductionmentioning

confidence: 99%

Zero Echo Time Magnetic Resonance Imaging of Contrast-Agent-Enhanced Calcium Phosphate Bone Defect Fillers

Sun

Ventura²,

Oosterwijk³

et al. 2013

Tissue Engineering Part C: Methods

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Calcium phosphate cements (CPCs) are widely used bone substitutes. However, CPCs have similar radiopacity as natural bone, rendering them difficult to be differentiated in classical X-ray and computed tomography imaging. As conventional magnetic resonance imaging (MRI) of bone is cumbersome, due to low water content and very short T 2 relaxation time, ultra-short echo time (UTE) and zero echo time (ZTE) MRI have been explored for bone visualization. This study examined the possibility to differentiate bone and CPC by MRI. T 1 and T 2 * values determined with UTE MRI showed little difference between bone and CPC; hence, these materials were difficult to separate based on T 1 or T 2 alone. Incorporation of ultra-small particles of iron oxide and gadopentetatedimeglumine (Gd-DTPA; 1 weight percentage [wt%] and 5 wt% respectively) into CPC resulted in visualization of CPC with decreased intensity on ZTE images in in vitro and ex vivo experiments. However, these additions had unfavorable effects on the solidification time and/or mechanical properties of the CPC, with the exception of 1% Gd-DTPA alone. Therefore, we tested this material in an in vivo experiment. The contrast of CPC was enhanced at an early stage postimplantation, and was significantly reduced in the 8 weeks thereafter. This indicates that ZTE imaging with Gd-DTPA as a contrast agent could be a valid radiation-free method to visualize CPC degradation and bone regeneration in preclinical experiments.

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“…A recent development has been the publication of a new bone identification technique, based on 3-dimensional radial zero-echo-time (ZTE) imaging (18). This sequence (similar to pointwise encoding time reduction with radial acquisition (19) and, to a certain extent, SWeep Imaging with Fourier Transformation (20)) has been proven to provide high-resolution isotropic images, suitable for bone segmentation-1.4 mm 3 in this study.…”

mentioning

confidence: 95%

Clinical Evaluation of Zero-Echo-Time MR Imaging for the Segmentation of the Skull

Delso¹,

et al. 2015

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MR-based attenuation correction is instrumental for integrated PET/ MR imaging. It is generally achieved by segmenting MR images into a set of tissue classes with known attenuation properties (e.g., air, lung, bone, fat, soft tissue). Bone identification with MR imaging is, however, quite challenging, because of the low proton density and fast decay time of bone tissue. The clinical evaluation of a novel, recently published method for zero-echo-time (ZTE)-based MR bone depiction and segmentation in the head is presented here. Methods: A new paradigm for MR imaging bone segmentation, based on proton density-weighted ZTE imaging, was disclosed earlier in 2014. In this study, we reviewed the bone maps obtained with this method on 15 clinical datasets acquired with a PET/CT/MR trimodality setup. The CT scans acquired for PET attenuation-correction purposes were used as reference for the evaluation. Quantitative measurements based on the Jaccard distance between ZTE and CT bone masks and qualitative scoring of anatomic accuracy by an experienced radiologist and nuclear medicine physician were performed. Results: The average Jaccard distance between ZTE and CT bone masks evaluated over the entire head was 52% ± 6% (range, 38%-63%). When only the cranium was considered, the distance was 39% ± 4% (range, 32%-49%). These results surpass previously reported attempts with dualecho ultrashort echo time, for which the Jaccard distance was in the 47%-79% range (parietal and nasal regions, respectively). Anatomically, the calvaria is consistently well segmented, with frequent but isolated voxel misclassifications. Air cavity walls and bone/fluid interfaces with high anatomic detail, such as the inner ear, remain a challenge. Conclusion: This is the first, to our knowledge, clinical evaluation of skull bone identification based on a ZTE sequence. The results suggest that proton density-weighted ZTE imaging is an efficient means of obtaining high-resolution maps of bone tissue with sufficient anatomic accuracy for, for example, PET attenuation correction.

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Ultra‐fast imaging using low flip angles and fids

Cited by 147 publications

References 7 publications

Acoustic noise reduction in MRI using Silent Scan: an initial experience

Acoustic noise reduction in MRI using Silent Scan: an initial experience

Zero Echo Time Magnetic Resonance Imaging of Contrast-Agent-Enhanced Calcium Phosphate Bone Defect Fillers

Clinical Evaluation of Zero-Echo-Time MR Imaging for the Segmentation of the Skull

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