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Keerthivasan MB, Winegar B, Becker JL, Bilgin A, Altbach MI, Saranathan M. Clinical Utility of a Novel Ultrafast T2-Weighted Sequence for Spine Imaging. AJNR Am J Neuroradiol 2018; 39:1568-1575. [PMID: 30002053 DOI: 10.3174/ajnr.a5713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 05/14/2018] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE TSE-based T2-weighted imaging of the spine has long scan times. This work proposes a fast imaging protocol using variable refocusing flip angles, optimized for blurring and specific absorption rate. MATERIALS AND METHODS A variable refocusing flip angle echo-train was optimized for the spine to improve the point spread function and minimize the specific absorption rate, yielding images with improved spatial resolution and SNR compared with the constant flip angle sequence. Data were acquired from 51 patients (35 lumbar, 16 whole-spine) using conventional TSE and the proposed sequence, with a single-shot variant for whole-spine. Noninferiority analysis was performed to evaluate the efficiency of the proposed technique. RESULTS The proposed multishot sequence resulted in a 2× shorter scan time with a >1.5× lower specific absorption rate. The variable flip angle sequence was noninferior to the conventional TSE (P < .025) for all image-quality and clinical criteria except signal-to-noise ratio for the lumbar spine protocol. However, mean image scores for the TSE-variable refocusing flip angle were ≥4.3 for all criteria, and concordance analysis showed high agreement (>90%) with the TSE, indicating clinical equivalence. The single-shot sequence resulted in 4× shorter whole-spine scans, and image scores were ≥4.4 for all criteria, attesting to its clinical utility. CONCLUSIONS We present a fast T2-weighted spine protocol using variable refocusing flip angles, including a single-shot variant. The sequences have better point spread function behavior than their constant flip angle counterparts and, being faster, should be less sensitive to patient motion, often seen in the longer TSE scans.
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Affiliation(s)
- M B Keerthivasan
- From the Departments of Electrical and Computer Engineering (M.B.K., A.B.).,Medical Imaging (M.B.K., B.W., J.L.B., M.I.A., M.S.)
| | - B Winegar
- Medical Imaging (M.B.K., B.W., J.L.B., M.I.A., M.S.)
| | - J L Becker
- Medical Imaging (M.B.K., B.W., J.L.B., M.I.A., M.S.)
| | - A Bilgin
- From the Departments of Electrical and Computer Engineering (M.B.K., A.B.).,Biomedical Engineering (A.B.) University of Arizona, Tucson, Arizona
| | - M I Altbach
- Medical Imaging (M.B.K., B.W., J.L.B., M.I.A., M.S.)
| | - M Saranathan
- Medical Imaging (M.B.K., B.W., J.L.B., M.I.A., M.S.)
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Lee H, Sohn CH, Park J. Rapid hybrid encoding for high-resolution whole-brain fluid-attenuated imaging. NMR IN BIOMEDICINE 2013; 26:1751-1761. [PMID: 24000143 DOI: 10.1002/nbm.3013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 05/28/2013] [Accepted: 07/16/2013] [Indexed: 06/02/2023]
Abstract
Single-slab three-dimensional (3D) turbo spin-echo (TSE) imaging combined with inversion recovery (IR), which employs short, spatially non-selective refocusing pulses and signal prescription based variable refocusing flip angles (VFA) to increase imaging efficiency, was recently introduced to produce fluid-attenuated brain images for lesion detection. Despite the advantages, the imaging efficiency in this approach still remains limited because a substantially long time of inversion is needed to selectively suppress the signal intensity of cerebrospinal fluid (CSF) while fully recovering that of brain tissues. The purpose of this work is to develop a novel, rapid hybrid encoding method for highly efficient whole-brain fluid-attenuated imaging. In each time of repetition, volumetric data are continuously encoded using the hybrid modular acquisition in a sequential fashion even during IR signal transition, wherein reversed fast imaging with steady-state free precession (PSIF) is employed to encode intermediate-to-high spatial frequency signals prior to CSF nulling, while VFA-TSE is used to collect low-to-intermediate spatial frequency signals afterwards. Gradient-induced spin de-phasing between a pair of neighboring radio-frequency (RF) pulses in both PSIF and TSE modules is kept identical to avoid the occurrence of multiple echoes in a single acquisition window. Additionally, a two-step, alternate RF phase-cycling scheme is employed in the low spatial frequency region to eliminate free induction decay induced edge artifacts. Numerical simulations of the Bloch equations were performed to evaluate signal evolution of brain tissues along the echo train while optimizing imaging parameters. In vivo studies demonstrate that the proposed technique produces high-resolution isotropic fluid-attenuated whole-brain images in a clinically acceptable imaging time with substantially high signal-to-noise ratio for white matter while retaining lesion conspicuity.
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Affiliation(s)
- Hoonjae Lee
- Biomedical Imaging and Engineering Lab, Department of Brain and Cognitive Engineering, Korea University, Seoul, Korea
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Bailey WM. Fast Fluid Attenuated Inversion Recovery (FLAIR) imaging and associated artefacts in Magnetic Resonance Imaging (MRI). Radiography (Lond) 2007. [DOI: 10.1016/j.radi.2006.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pease A, Sullivan S, Olby N, Galano H, Cerda-Gonzalez S, Robertson ID, Gavin P, Thrall D. VALUE OF A SINGLE-SHOT TURBO SPIN-ECHO PULSE SEQUENCE FOR ASSESSING THE ARCHITECTURE OF THE SUBARACHNOID SPACE AND THE CONSTITUTIVE NATURE OF CEREBROSPINAL FLUID. Vet Radiol Ultrasound 2006; 47:254-9. [PMID: 16700175 DOI: 10.1111/j.1740-8261.2006.00136.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Three case history reports are presented to illustrate the value of the single-shot turbo spin-echo pulse sequence for assessment of the subarachnoid space. The use of the single-shot turbo spin-echo pulse sequence, which is a heavily T2-weighted sequence, allows for a rapid, noninvasive evaluation of the subarachnoid space by using the high signal from cerebrospinal fluid. This sequence can be completed in seconds rather than the several minutes required for a T2-fast spin-echo sequence. Unlike the standard T2-fast spin-echo sequence, a single-shot turbo spin-echo pulse sequence also provides qualitative information about the protein and the cellular content of the cerebrospinal fluid, such as in patients with inflammatory debris or hemorrhage in the cerebrospinal fluid. Although the resolution of the single-shot turbo spin-echo pulse sequence images is relatively poor compared with more conventional sequences, the qualitative information about the subarachnoid space and cerebrospinal fluid and the rapid acquisition time, make it a useful sequence to include in standard protocols of spinal magnetic resonance imaging.
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Affiliation(s)
- Anthony Pease
- Department of Molecular Biomedical Sciences North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27603, USA.
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Diagnostic value of contrast-enhanced fluid-attenuated inversion-recovery MRI for intracranial tumors in comparison with post-contrast T1W spin-echo MRI. Chin Med J (Engl) 2006. [DOI: 10.1097/00029330-200603020-00006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
Continuous technologic developments and research have increased the clinical applications of MT, HASTE, and FLAIR imaging in neuroradiology. HASTE has become the MR imaging sequence of choice for fetal neuroimaging. Other promising uses, such as for diffusion-weighted imaging, have not been fully exploited. FLAIR has been firmly established as one of the cornerstones of brain imaging; however, post-contrast FLAIR images have not offered a clear advantage over standard T1-weighted images as suggested by early studies. FLAIR imaging with echoplanar acquisition is not considered advantageous, because the decreased imaging times are obtained at the expense of lower sensitivity. For a number of applications, diffusion-weighted imaging has surpassed FLAIR. Nevertheless, FLAIR images may be more sensitive for the detection of acute brain infarction. Recently described methods for the elimination of CSF flow artifacts may lead to improved quality and reliability of FLAIR images for subarachnoid space disease. MT preparation is now routinely incorporated in time-of-flight MR angiography and gradient-echo T2*-weighted spine imaging sequences and provides increased sensitivity for postcontrast MR imaging. These applications may not be advantageous in all clinical settings. MTR analysis offers valuable information for an increasing number of pathologic processes but has not yet gained wide clinical acceptance owing to sophisticated postprocessing and significant intercenter variations. Different modifications of these techniques are being evaluated, and further developments are expected.
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Affiliation(s)
- Zoran Rumboldt
- Department of Radiology, Medical University of South Carolina, 169 Ashley Avenue, Post Office Box 250322, Charlestown, SC 29425, USA.
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Beall DP, Fortman BJ, Lawler BC, Regan F. Imaging bowel obstruction: a comparison between fast magnetic resonance imaging and helical computed tomography. Clin Radiol 2002; 57:719-24. [PMID: 12169282 DOI: 10.1053/crad.2001.0735] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM To compare the accuracy of fast magnetic resonance (MR) imaging using the half-Fourier single shot turbo spin echo (HASTE) sequence with helical computed tomography (CT) in diagnosing bowel obstruction. MATERIALS AND METHODS Prospective evaluation of 44 patients with clinical evidence of bowel obstruction was conducted using various investigations including HASTE MR and helical CT. MR was performed with a Siemens 1.5 Tesla MR Imaging System and CT was performed with one of two Siemens ARHP CT systems using helical technique. MR acquisition allowed data to be gathered in 6-10 minutes and no contrast media were administered. CT imaging consisted of consecutive helical CT through the abdomen and pelvis with oral and intravenous contrast medium used when indicated. Bowel dilation along with the presence and level of obstruction were determined. RESULTS Twenty-eight patients had bowel obstruction confirmed at laparotomy or by radiographic assessment. Of these, 25 had small bowel obstruction and three had colonic obstructions. The obstruction was due to fibrous adhesions in nine patients, metastases or primary carcinoma in seven, Crohn's disease in four, hernias in two, and inflammation or abscess in two. Other causes of obstruction included lymphoma, intussusception and anastomotic stricture. The cause of obstruction was correctly diagnosed by CT in 71%, and by MR in 95% of cases. The sensitivity, specificity and accuracy for HASTE MR imaging was 95%, 100% and 96% respectively as compared to 71%, 71% and 71% for helical CT. CONCLUSION Fast MR imaging using the HASTE sequence is more accurate than helical CT in diagnosing bowel obstruction.
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Affiliation(s)
- D P Beall
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, U.S.A.
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Penzkofer AK, Pfluger T, Pochmann Y, Meissner O, Leinsinger G. MR imaging of the brain in pediatric patients: diagnostic value of HASTE sequences. AJR Am J Roentgenol 2002; 179:509-14. [PMID: 12130464 DOI: 10.2214/ajr.179.2.1790509] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of this study was to determine the diagnostic value of half-Fourier single-shot turbo spin-echo (HASTE) sequences in MR imaging of the brain in pediatric patients. SUBJECTS AND METHODS HASTE sequences were performed in 80 infants and children. Two radiologists who were unaware of the patients' medical histories independently reviewed the images for the presence of nine findings: defects of the parenchyma, hypoplasia or agenesis of the corpus callosum, edema, signs of increased intracranial pressure, myelination disorders, migration disorders, malformations, tumors, and widening of spaces of the cerebrospinal fluid. A conventional MR imaging examination that served as the reference examination was evaluated by the same two radiologists in a final consensus interpretation. The findings detected on the HASTE images were compared with the findings seen on the conventional MR images. The sensitivity and specificity of HASTE sequences were calculated, and Cohen's kappa statistic was used to determine interobserver agreement. RESULTS Both radiologists correctly diagnosed all 20 defects of the parenchyma that were present in the patients. Radiologist 1 correctly identified 20 and radiologist 2 correctly identified 21 of the 22 patients with hypoplasia or agenesis of the corpus callosum. Both radiologists correctly diagnosed edema in eight of the nine patients in whom edema was present, and both correctly identified signs of increased intracranial pressure in eight of the nine children who had this condition. Radiologist 1 correctly diagnosed seven and radiologist 2 correctly identified nine of the 11 cases of myelination disorders. Both radiologists correctly diagnosed six of the 14 cases with migration disorders. All 13 brain malformations present in the patients were correctly identified by both reviewers. Both radiologists correctly identified all 11 patients with tumors, and both correctly identified all 35 patients with widening of spaces of the cerebrospinal fluid. CONCLUSION HASTE images are highly sensitive for excluding the presence of brain tumor, hydrocephalus, or malformations of the brain. HASTE images are not reliable for evaluating patients with suspected myelination disorders or migration disorders.
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Affiliation(s)
- Andrea K Penzkofer
- Department of Clinical Radiology, Klinikum Innenstadt, Ludwig Maximilans University of Munich, Ziemssenstr. 1, 80336 Munich, Germany
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Singh SK, Agris JM, Leeds NE, Ginsberg LE. Intracranial leptomeningeal metastases: comparison of depiction at FLAIR and contrast-enhanced MR imaging. Radiology 2000; 217:50-3. [PMID: 11012422 DOI: 10.1148/radiology.217.1.r00oc3550] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To compare contrast material-enhanced T1-weighted and fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) images in depicting leptomeningeal metastases. MATERIALS AND METHODS Malignant lesions detected at cytologic examination of cerebrospinal fluid in 70 patients were reviewed. There were 58 studies in which both FLAIR and contrast-enhanced T1-weighted spin-echo MR images were available. A senior neuroradiologist reviewed the images from each sequence individually and separately for signs of leptomeningeal metastases and assigned a diagnostic rating of positive, indeterminate, or negative. RESULTS Leptomeningeal metastases were depicted in 38 cases on contrast-enhanced T1-weighted spin-echo images and in 20 cases on FLAIR images. In three cases, leptomeningeal metastases were detected by using only FLAIR images. In 20 cases, leptomeningeal metastases were detected by using only contrast-enhanced T1-weighted spin-echo images. FLAIR imaging has a sensitivity of 34% for cytologically proved leptomeningeal metastases. Gadolinium-enhanced MR imaging has a sensitivity of 66%. CONCLUSION Used alone, contrast-enhanced T1-weighted images are better than FLAIR images for detecting leptomeningeal metastases. This is particularly true for cases in which leptomeningeal metastases manifest primarily or solely as cranial nerve involvement.
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Affiliation(s)
- S K Singh
- Department of Diagnostic Radiology, University of Texas M.D. Anderson Cancer Center, Box 57, 1515 Holcombe Blvd, Houston, TX 77030, USA.
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Rouanet De Lavit JP, Maubon AJ, Thurmond AS. MR hysterography performed with saline injection and fluid attenuated inversion recovery sequences: initial experience. AJR Am J Roentgenol 2000; 175:774-6. [PMID: 10954465 DOI: 10.2214/ajr.175.3.1750774] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- J P Rouanet De Lavit
- Radiology Department, C.M.C. Beausoleil, 119 Ave. de Lodeve, 34000 Montpellier, France
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