Basic pulse sequences

Pulse sequences control the timing of radiofrequency pulses and time-varying gradients that are necessary to create an image. Sequences are divided into different types: gradient echo, spin echo, and hybrid echo sequences. In cardiac imaging, ‘black blood’ spin echo images are used for anatomical imaging, while ‘bright blood’ imaging is used to study function and is based on gradient echo or hybrid echo sequences. Some key applications of those sequences, e.g. water–fat imaging or T2*-mapping to detect iron loading, are discussed. Preparation pulses can be used to modify image contrast to, for example, improve black blood images or for quantitative applications, including T1- and T2-mapping. To help the reader navigate through the sea of sequence acronyms, the chapter ends with a quick guide covering the acronyms used by the main scanner manufacturers.

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Experimental intracerebral and subarachnoid/intraventricular haemorrhages: MR detectability at 0.5 T and 1.5 T

Acta Radiologica ◽

10.1258/rsmacta.43.5.464 ◽

2002 ◽

Vol 43 (5) ◽

pp. 464-473

Author(s):

M. Alemany Ripoll ◽

R. Raininko

Keyword(s):

Cerebrospinal Fluid ◽

Mr Imaging ◽

Spin Echo ◽

Autologous Blood ◽

Pulse Sequences ◽

Proton Density ◽

Gradient Echo ◽

The Brain ◽

Formalin Fixed

Purpose: To compare the detectability of small experimental intracranial haemorrhages on MR imaging at 0.5 T and 1.5 T, from hyperacute to subacute stages. Material and Methods: 1 ml of autologous blood was injected into the brain of 15 rabbits to create intraparenchymal haematomas. Since the blood partially escaped into the cerebrospinal fluid (CSF) spaces, detectability of subarachnoid and intraventricular blood was also evaluated. MR imaging at 0.5 T and at 1.5 T was repeated up to 14 days, including T1-, proton density- and T2-weighted (w) spin-echo (SE), FLAIR and T2*-w gradient echo (GE) pulse sequences. The last MR investigation was compared to the formalin-fixed brain sections in 7 animals. Results: The intraparenchymal haematomas were best revealed with T2*-w GE sequences, with 100% of sensitivity at 1.5 T and 90–95% at 0.5 T. Blood in the CSF spaces was significantly ( p < 0.05) better detected at 1.5 T with T2*-w GE sequences and detected best during the first 2 days. The next most sensitive sequence for intracranial blood was FLAIR. SE sequences were rather insensitive. Conclusion: 1.5 T equipment is superior to 0.5 T in the detection of intracranial haemorrhages from acute to subacute stages. T2*-w GE sequences account for this result but other sequences are also needed for a complete examination.

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Improvement of the Diagnostic Performance of Facial Neuritis Using Contrast-Enhanced 3D T1 Black-Blood Imaging: Comparison with Contrast-Enhanced 3D T1-Spoiled Gradient-Echo Imaging

Journal of Clinical Medicine ◽

10.3390/jcm10091850 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1850

Author(s):

Seun-Ah Lee ◽

Sang-Won Jo ◽

Suk-Ki Chang ◽

Ki-Han Kwon

Keyword(s):

Quantitative Analysis ◽

Diagnostic Performance ◽

Spin Echo ◽

Fast Spin Echo ◽

Black Blood ◽

Gradient Echo ◽

Diagnostic Confidence ◽

Contrast Enhanced ◽

Black Blood Imaging ◽

Spoiled Gradient Echo

This study aims to investigate the diagnostic ability of the contrast-enhanced 3D T1 black-blood fast spin-echo (T1 BB-FSE) sequence compared with the contrast-enhanced 3D T1-spoiled gradient-echo (CE-GRE) sequence in patients with facial neuritis. Forty-five patients with facial neuritis who underwent temporal bone MR imaging, including T1 BB-FSE and CE-GRE imaging, were examined. Two reviewers independently assessed the T1 BB-FSE and CE-GRE images in terms of diagnostic performance, and qualitative (diagnostic confidence and visual asymmetric enhancement) and quantitative analysis (contrast-enhancing lesion extent of the canalicular segment of the affected facial nerve (LEC) and the affected side-to-normal signal intensity ratio (rSI)). The AUCs of each reviewer, and the sensitivity and accuracy of T1 BB-FSE were significantly superior to those of CE-GRE (p < 0.05). Regarding diagnostic confidence and visual asymmetric enhancement, T1 BB-FSE tended to be rated greater than CE-GRE (p < 0.05). Additionally, in quantitative analysis, LEC and rSI of the canalicular segment on T1 BB-FSE were larger than those on CE-GRE (p < 0.05). The T1 BB-FSE sequence was significantly superior to the CE-GRE sequence, with more conspicuous lesion visualization in terms of both qualitative and quantitative aspects in patients with facial neuritis.

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3D Fast Spin-Echo T1 Black-Blood Imaging for the Diagnosis of Cervical Artery Dissection

American Journal of Neuroradiology ◽

10.3174/ajnr.a3261 ◽

2012 ◽

Vol 34 (9) ◽

pp. E103-E106 ◽

Cited By ~ 43

Author(s):

M. Edjlali ◽

P. Roca ◽

C. Rabrait ◽

O. Naggara ◽

C. Oppenheim

Keyword(s):

Spin Echo ◽

Fast Spin Echo ◽

Artery Dissection ◽

Cervical Artery Dissection ◽

Black Blood ◽

Black Blood Imaging ◽

Cervical Artery ◽

Blood Imaging ◽

Fast Spin

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Magnetic resonance coronary angiography to evaluate coronary arterial lesions in patients with Kawasaki disease

Cardiology in the Young ◽

10.1017/s1047951106001168 ◽

2006 ◽

Vol 16 (6) ◽

pp. 563-571 ◽

Cited By ~ 31

Author(s):

Atsuko Suzuki ◽

Atsushi Takemura ◽

Rikako Inaba ◽

Tomoyoshi Sonobe ◽

Keiji Tsuchiya ◽

...

Keyword(s):

Magnetic Resonance ◽

Kawasaki Disease ◽

Coronary Angiography ◽

Black Blood ◽

X Ray ◽

Magnetic Resonance Coronary Angiography ◽

Arterial Lesions ◽

Black Blood Imaging ◽

Blood Imaging ◽

Bright Blood

We evaluated the efficiency of non-invasive magnetic resonance coronary angiography in detecting coronary arterial lesions in 106 patients, aged from 4 months to 37 years, with a median of 13 years, with Kawasaki disease. Non-contrast enhanced, free-breathing magnetic resonance coronary angiographic studies using both the steady-state free precession technique, namely bright blood imaging, and navigator-echo proton density weighted black blood imaging, so-called black blood imaging, were performed in all the patients. Conventional X-ray coronary angiography was performed in 70 patients with coronary arterial lesions.We observed 97 aneurysms, 17 dilatations, 17 occlusions, 18 localized stenoses and 10 recanalized vessels, and we clarified their unique pattern of images on magnetic resonance coronary angiography. The differences in size of the aneurysms as seen on X-ray coronary angiography and bright blood imaging was mean 0.0, and the 95% confidence interval was from −1.4 to 1.5 on the Bland-Altman plots. With bright blood imaging, the sensitivity of occlusion and localized stenosis based on X-ray angiography was 94.2% and 97.2%, specificity was 99.5% and 97.2%, and negative-predictive value was 99.5% and 97.2%, respectively. Black blood imaging provided remarkable visualization of the thickened intima of aneurysms, and/or thrombus, in 38 lesions. We conclude that magnetic resonance coronary angiography can visualize all types of lesions due to Kawasaki disease in patients of all ages, and that it is useful to reduce the number of times X-ray angiography needs to be performed in patients with Kawasaki disease.

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Quantitative Radiomics: Impact of Pulse Sequence Parameter Selection on MRI-Based Textural Features of the Brain

Contrast Media & Molecular Imaging ◽

10.1155/2018/1729071 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 27

Author(s):

John Ford ◽

Nesrin Dogan ◽

Lori Young ◽

Fei Yang

Keyword(s):

Pulse Sequence ◽

Spin Echo ◽

Pulse Sequences ◽

Parameter Selection ◽

Inversion Recovery ◽

Textural Features ◽

Imaging Data ◽

Gradient Echo ◽

The Impact ◽

The Brain

Objectives. Radiomic features extracted from diverse MRI modalities have been investigated regarding their predictive and/or prognostic value in a variety of cancers. With the aid of a 3D realistic digital MRI phantom of the brain, the aim of this study was to examine the impact of pulse sequence parameter selection on MRI-based textural parameters of the brain. Methods. MR images of the employed digital phantom were realized with SimuBloch, a simulation package made for fast generation of image sequences based on the Bloch equations. Pulse sequences being investigated consisted of spin echo (SE), gradient echo (GRE), spoiled gradient echo (SP-GRE), inversion recovery spin echo (IR-SE), and inversion recovery gradient echo (IR-GRE). Twenty-nine radiomic textural features related, respectively, to gray-level intensity histograms (GLIH), cooccurrence matrices (GLCOM), zone size matrices (GLZSM), and neighborhood difference matrices (GLNDM) were evaluated for the obtained MR realizations, and differences were identified. Results. It was found that radiomic features vary considerably among images generated by the five different T1-weighted pulse sequences, and the deviations from those measured on the T1 map vary among features, from a few percent to over 100%. Radiomic features extracted from T1-weighted spin-echo images with TR varying from 360 ms to 620 ms and TE = 3.4 ms showed coefficients of variation (CV) up to 45%, while up to 70%, for T2-weighted spin-echo images with TE varying over the range 60–120 ms and TR = 6400 ms. Conclusion. Variability of radiologic textural appearance on MR realizations with respect to the choice of pulse sequence and imaging parameters is feature-dependent and can be substantial. It calls for caution in employing MRI-derived radiomic features especially when pooling imaging data from multiple institutions with intention of correlating with clinical endpoints.

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