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Quantitative Versus Qualitative Methods in Evaluation of T2 Signal Intensity to Improve Accuracy in Diagnosis of Pheochromocytoma. AJR Am J Roentgenol 2015. [PMID: 26204279 DOI: 10.2214/ajr.14.13273] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this study was to assess T2 signal intensity (SI) of adrenal pheochromocytoma at 1.5 T using the rapid acquisitions with relaxation enhancement (RARE) sequence. We also sought to determine whether quantitative parameters can distinguish pheochromocytoma from other adrenal lesions with better accuracy than conventional qualitative methods. MATERIALS AND METHODS MRI examinations of 74 patients (26 with pheochromocytoma, 25 with lipid-poor adenomas, 18 with malignant adrenal lesions, and five with adrenal cysts) were retrospectively reviewed. MRI sequences included single-shot fast spin-echo (n = 38) and fast-recovery fast spin-echo (n = 36) acquisitions. T2 SI of lesions was qualitatively compared with CSF. Quantitative evaluation included applying ROI measurements and calculating SI ratio of each mass to liver, spleen, paraspinal muscle, and CSF. Twoway ANOVA compared SI ratios between different adrenal lesions and between two pulse sequences. ROC analysis determined the optimal threshold SI ratio for distinguishing pheochromocytomas from other adrenal lesions. RESULTS Sixty-nine percent of pheochromocytomas displayed isointensity to CSF (p < 0.005), resulting in 81% specificity and 69% sensitivity for differentiation of pheochromocytomas from lipid-poor adenomas and malignant lesions. Adrenal-to-muscle SI ratio was the strongest discriminator for differentiation of pheochromocytomas from other lesions. A threshold of at least 3.95 yielded 88% specificity and 81% sensitivity for distinguishing pheochromocytomas from lipid-poor adenomas and malignant adrenal lesions. CONCLUSION Quantitative normalization of T2 SI with reference to muscle improves the sensitivity and specificity profile for differentiation of pheochromocytoma compared with qualitative assessment alone. At 1.5 T field strength, an adrenal-to-muscle SI ratio of at least 3.95 is recommended.
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T2-weighted magnetic resonance imaging of the liver: evaluation of the effect in signal intensity after Gd-EOB-DTPA enhancement. J Comput Assist Tomogr 2010; 34:182-6. [PMID: 20351500 DOI: 10.1097/rct.0b013e3181bc961b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To evaluate the effect of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) on T2-weighted magnetic resonance imaging of liver parenchyma. METHODS Forty-six patients with suspected hepatic tumors (group 1) underwent breath-hold T2-weighted fast spin echo imaging before and after 4 minutes of Gd-EOB-DTPA enhancement. Visual assessment and signal intensity (SI) measurements were performed to evaluate the effects of Gd-EOB-DTPA on the T2-weighted images of the liver. Thirteen healthy volunteers (Group 2) who underwent magnetic resonance imaging before and after 35 minutes of Gd-EOB-DTPA enhancement were also evaluated. RESULTS In the qualitative analysis, visual SI of hepatic vessels after enhancement was significantly higher than that before enhancement (P < 0.001) in group 1, although there was no significant difference in the visual SI of liver parenchyma between before and after enhancement. In the quantitative analysis, SI ratio of liver parenchyma on enhanced images was significantly higher than that on unenhanced images (P < 0.001) in group 1. Conversely, the SI ratio (P < 0.001) and the visual SI (P = 0.008) in group 2 were significantly lower on the enhanced images than on the unenhanced images. CONCLUSIONS The T2-weighted images obtained during the early phase after enhancement will appear similar to those of the unenhanced T2-weighted images, whereas later images will show a reduced signal of the liver parenchyma.
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2D Thick-Slab MR Cholangiopancreatography: Does Parallel Imaging with Sensitivity Encoding Improve Image Quality and Duct Visualization? AJR Am J Roentgenol 2008; 190:W327-34. [DOI: 10.2214/ajr.07.2854] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Effect of T1 Shortening on T2-Weighted MRI Sequences: Comparison of Hepatic Mass Conspicuity on Images Acquired Before and After Gadolinium Enhancement. AJR Am J Roentgenol 2008; 190:1318-23. [DOI: 10.2214/ajr.07.2696] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Herborn CU, Vogt FM, Lauenstein TC, Goyen M, Debatin JF, Ruehm SG. Evaluation of steady state free precession imaging of the pancreas. Eur Radiol 2005; 15:1629-33. [PMID: 15841379 DOI: 10.1007/s00330-005-2774-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 03/25/2005] [Accepted: 04/05/2005] [Indexed: 10/25/2022]
Abstract
The aim of this work was to assess the diagnostic value of fast steady state free precession (SSFP) for the detection, characterization, and delineation of pancreatic lesions. Forty-eight patients referred for magnetic resonance (MR) imaging of the pancreas were included in the study. In addition to the standard protocol, axial pre-contrast SSFP slices of the pancreas were acquired. The standard of reference was defined as based on all imaging data other than SSFP, histopathology, surgery, and/or clinical follow-up. A randomized consensus reading of the SSFP data sets was retrospectively conducted by two board-certified radiologists. The presence of pancreatic lesions, local infiltration, and lymph node metastases was evaluated. Sensitivity and specificity were calculated and a receiver operating characteristic (ROC) analysis was performed. The overall sensitivity and specificity of SSFP were 0.93 and 0.77, respectively. Comparable values were achieved for lymph node detection (0.88/0.91) and assessment of vascular infiltration (0.94/0.91). The mean area under the ROC curve (Az) was 0.91. Owing to its potential to detect vascular infiltration and the rapid acquisition time, SSFP imaging should be supplemented as part of a standard MR protocol of the pancreas.
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Affiliation(s)
- Christoph U Herborn
- Department of Radiology, Scott and White Clinic and Hospital, Temple, TX, USA.
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Klessen C, Asbach P, Kroencke TJ, Fischer T, Warmuth C, Stemmer A, Hamm B, Taupitz M. Magnetic resonance imaging of the upper abdomen using a free-breathing T2-weighted turbo spin echo sequence with navigator triggered prospective acquisition correction. J Magn Reson Imaging 2005; 21:576-82. [PMID: 15834908 DOI: 10.1002/jmri.20293] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To evaluate a free-breathing navigator triggered T2-weighted turbo spin-echo sequence with prospective acquisition correction (T2w-PACE-TSE) for MRI of the upper abdomen in comparison to a conventional T2-weighted TSE (T2w-CTSE), a single-shot TSE (T2w-HASTE), and a T1-weighted gradient-echo sequence (T1w-FLASH). MATERIALS AND METHODS A total of 40 consecutive patients were examined at 1.5 T using free-breathing T2w-PACE-TSE, free-breathing T2w-CTSE, and breath-hold T2w-HASTE and T1w-FLASH acquisition. Images were evaluated qualitatively by three radiologists regarding motion artifacts, liver-spleen contrast, depiction of intrahepatic vessels, the pancreas and the adrenal glands, and overall image quality on a four-point scale. Quantitative analysis of the liver-spleen contrast was performed. RESULTS Depiction and sharpness of intrahepatic vessels were rated significantly better (P < 0.01) using T2w-PACE-TSE compared to T2w-CTSE and T2w-HASTE sequences. Significantly higher contrast values were measured for T2w-PACE-TSE images compared to T2w-CTSE, T2w-HASTE, and T1w-FLASH images (P < 0.01). Mean examination time of the T2w-PACE-TSE was 7.91 minutes, acquisition time of the T2w-CTSE sequence was 4.52 minutes. CONCLUSION Prospective acquisition correction is an efficient method for reducing respiratory movement artifacts in T2w-TSE imaging of the upper abdomen. Compared to T2w-CTSE and T2w-HASTE sequences recognition of anatomical details and contrast can be significantly improved.
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Affiliation(s)
- Christian Klessen
- Department of Radiology, Charité-Universitary Medicine Berlin, Campus Charité Mitte, Humboldt-University of Berlin, Berlin, Germany.
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Santa-Marta C, Lafuente J, Vaquero JJ, Garcia-Barreno P, Desco M. Resolution recovery in Turbo Spin Echo using segmented Half Fourier acquisition. Magn Reson Imaging 2004; 22:369-78. [PMID: 15062932 DOI: 10.1016/j.mri.2004.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2003] [Accepted: 01/23/2004] [Indexed: 11/20/2022]
Abstract
Turbo Spin Echo (TSE) is a sequence of choice for obtaining T(2)-weighted images. TSE reduces acquisition time by acquiring several echoes within each TR, at the cost of introducing an exponential weighting in the k-space that leads to a certain image blurring. This is particularly important for short-T(2) structures, which can even disappear if their size in the phase encoding direction is comparable to the degree of blurring. This article suggests the use of a combination of Half Fourier (HF) and segmented (multishot) TSE (sHF-TSE) to recover the original resolution of the SE images. The improved symmetry of the dataset achieved by HF reconstruction is used to increase the resolution of the TSE images. The proposed combination, available in most clinical scanners, reduces the blurring artifact inherent to the TSE sequence without increasing the scan time or the number of acquisitions, but at the cost of a slight reduction of the signal-to-noise ratios (SNR). Qualitative and quantitative results are presented using both numerical simulation and imaging. Significant edge enhancement has been achieved for structures with short T(2), (narrowing of the full width at half maximum [FWHM] up to 45%). The proposed sequence is more sensitive to movement artifacts but has proven to be superior to the conventional TSE for imaging static structures.
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Affiliation(s)
- Cristina Santa-Marta
- Unidad de Medicina y Cirugía Experimental, Hospital General Universitario Gregorio Maranon, Madrid, Spain
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Li T, Mirowitz SA. Fast T2-weighted MR imaging: impact of variation in pulse sequence parameters on image quality and artifacts. Magn Reson Imaging 2003; 21:745-53. [PMID: 14559339 DOI: 10.1016/s0730-725x(03)00173-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to quantitatively evaluate in a phantom model the practical impact of alteration of key imaging parameters on image quality and artifacts for the most commonly used fast T(2)-weighted MR sequences. These include fast spin-echo (FSE), single shot fast spin-echo (SSFSE), and spin-echo echo-planar imaging (EPI) pulse sequences. We developed a composite phantom with different T1 and T2 values, which was evaluated while stationary as well as during periodic motion. Experiments involved controlled variations in key parameters including effective TE, TR, echo spacing (ESP), receive bandwidth (BW), echo train length (ETL), and shot number (SN). Quantitative analysis consisted of signal-to-noise ratio (SNR), image nonuniformity, full-width-at-half-maximum (i.e., blurring or geometric distortion) and ghosting ratio. Among the fast T(2)-weighted sequences, EPI was most sensitive to alterations in imaging parameters. Among imaging parameters that we tested, effective TE, ETL, and shot number most prominently affected image quality and artifacts. Short T(2) objects were more sensitive to alterations in imaging parameters in terms of image quality and artifacts. Optimal clinical application of these fast T(2)-weighted imaging pulse sequences requires careful attention to selection of imaging parameters.
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Affiliation(s)
- Tao Li
- Department of Radiology University of Maryland Medical Center 22 South Greene Street, Baltimore, MD 21201-1595, USA.
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Abstract
In this article we describe state-of-the art techniques for magnetic resonance imaging of the liver. T1-weighted, T2-weighted, and heavily T2-weighted pulse sequences are discussed. Gadolinium-enhanced hepatic parenchymal imaging and magnetic resonance angiography are also described. A comprehensive MR imaging examination of the liver affords evaluation of focal and diffuse hepatic parenchymal disease, biliary disease, and vascular pathology.
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Affiliation(s)
- Adam R Fisher
- Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Jeong YY, Mitchell DG, Holland GA. Liver lesion conspicuity: T2-weighted breath-hold fast spin-echo MR imaging before and after gadolinium enhancement--initial experience. Radiology 2001; 219:455-60. [PMID: 11323472 DOI: 10.1148/radiology.219.2.r01ma09455] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the effect of a gadolinium chelate on T2-weighted breath-hold fast spin-echo magnetic resonance images of focal hepatic lesions. MATERIALS AND METHODS In 21 patients with focal hepatic lesions, identical T2-weighted breath-hold fast spin-echo images were obtained before and after gadolinium enhancement and were compared regarding lesion-to-liver contrast-to-noise ratio, signal-to-noise ratio, lesion conspicuity, and vascular pulsation artifact. Image review was performed independently, in random order, by two experienced radiologists. RESULTS For solid lesions, the lesion-to-liver contrast-to-noise ratio on enhanced images was significantly higher (P <.05) than that on nonenhanced images. For nonsolid lesions, however, there was no significant difference (P =.07). For both readers, lesion conspicuity for solid lesions on enhanced images was significantly higher than on nonenhanced images (P <.05). Severity of vascular pulsation artifact was not significantly different. CONCLUSION Solid-lesion contrast on T2-weighted breath-hold fast spin-echo images improves after administration of a gadolinium chelate. These images should be obtained after, rather than before, gadolinium enhancement.
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Affiliation(s)
- Y Y Jeong
- Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, 1096 Main Bldg, Philadelphia, PA 19107, USA
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Kangarlu A, Abduljalil AM, Schwarzbauer C, Norris DG, Robitaille PM. Human rapid acquisition with relaxation enhancement imaging at 8 T without specific absorption rate violation. MAGMA (NEW YORK, N.Y.) 1999; 9:81-4. [PMID: 10555177 DOI: 10.1007/bf02634596] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A standard fast imaging sequence, rapid acquisition with relaxation enhancement (RARE), has been applied to human magnetic resonance at 8 T. RARE is known for its speed, good contrast and high RF power content. Highly T2 weighted images, the hallmark of RARE imaging, were acquired from the human brain. It is demonstrated that while T2 values may be reduced at 8 T, high quality RARE images could still be acquired at this field strength. Most importantly however, it is demonstrated that RARE images could be acquired without violating specific absorption rate (SAR) guidelines. Since it is well known that T2 weighted images are of significant value in clinical diagnosis, the implementation of RARE at this field strength will provide ultra high field MRI (UHFMRI) with a valuable imaging protocol at this field strength without exceeding SAR limitations.
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Affiliation(s)
- A Kangarlu
- Department of Radiology, MRI Facility, The Ohio State University, Columbus 43210, USA
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Helmberger TK, Schröder J, Holzknecht N, Gregor M, Heuck A, Petsch R, Reiser MF. T2-weighted breathold imaging of the liver: a quantitative and qualitative comparison of fast spin echo and half Fourier single shot fast spin echo imaging. MAGMA (NEW YORK, N.Y.) 1999; 9:42-51. [PMID: 10555172 DOI: 10.1007/bf02634591] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The imaging characteristics of two EPI-hybrid breath-hold sequences, T2-weighted fast spin-echo [FSE, effective echo time (TEeff) 138 ms] and half Fourier single shot turbo spin-echo (HASTE, TEeff 60 ms), were compared in hepatic imaging. A total of 111 patients with suspected hepatic disease were studied at 1.5 Tesla using a body phase-array coil. The signal-to-noise (S/N) and contrast-to-noise (C/N) ratios for organs and lesions were calculated and quantitatively compared. Organ delineation, visualization of anatomical structures and pathological lesions, artifacts, and total image quality were qualitatively assessed and statistically compared. The final diagnoses were metastases from colorectal, breast, and pancreatic cancer in 23/111, hepatocellular carcinoma in 15/111, cysts in 19/111, hemangiomas in 9/111, several other lesions in 7/111, and no lesions in 38/111 of the cases. A total of 139 lesion in 73% of the patients were seen while 85% of the lesions were at least 1.5 cm in size. Regarding S/Ns HASTE was significantly (P < 0.03) superior to FSE with only minor (P > 0.05) differences in C/Ns between the two sequences for anatomical and pathological structures. HASTE demonstrated in almost all (97.3%) of the cases no artifacts, while on fast SE imaging moderate to minor artifacts were present in 23.5-51.7% of the cases. The overall image quality and diagnostic confidence was rated significantly higher (good 43.2%, excellent 53.2%) for HASTE than for fast SE imaging (good 44.8%, excellent 17.6%). Providing comparable C/Ns for anatomical and pathological structures, breatheld HASTE imaging proved to be superior to fast SE in T2-weighted imaging of the upper abdomen regarding general image quality, and, with adequate technical prerequisites, may be a suitable substitute of fast T2-imaging techniques.
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Affiliation(s)
- T K Helmberger
- Institute of Diagnostic Radiology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
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Jafari F, Nayeri N, Tahsini M, Khodadoust AA. Differentiation of hepatic cavernous hemangioma from metastases by rare sequence MR imaging. Magn Reson Imaging 1999; 17:669-77. [PMID: 10372520 DOI: 10.1016/s0730-725x(99)00008-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In this study, in order to differentiate cavernous hemangioma and hepatic metastases, rapid acquisition relaxation enhanced (RARE) sequence was used. First, in vivo measurements of T1, T2 relaxation times and proton density were obtained using T1, T2 calculation protocol (TOMIKON S50, 0.5T) and multipoint techniques. These measurements were made from regions of interest placed over the liver, spleen (because of similarity of relaxation time values between hepatic metastases and spleen) and cavernous hemangioma (HCH). Based on these intrinsic parameters, T2 curves signal intensity of three different tissues were constructed. At TE = 500 ms, the signal intensity of the liver and spleen has been near zero whereas in HCH, the signal intensity remained. As RARE sequence is very similar to spin echo (SE), by replacing effective TE(ETE) = 500 ms in the RARE equation, two dimensional contrast-to-noise ratio (CNR) contour plots were constructed demonstrating signal intensity contrast between liver-spleen, liver-Hemangioma for two different scan times (3 min, 7.5 s) and pulse timing. Then, optimal RARE factor and inter echo times were obtained in order to have maximum CNR between liver-Hemangioma and minimum CNR between liver-spleen. These optimal parameters were performed on ten normal and five persons with known HCH. Images showed that in both scan times (3 min, 7.5 s); the liver and spleen were suppressed whereas the HCH was enhanced. The image quality in the scan time of 3 min was better than the scan time of 7.5 s. Moreover, in this study, two different sequences were compared: i) Multi-slice single echo (MSSE) for T1 weighted image ii) RARE (ETE = 80 ms) for T2-weighted image. This comparison was done to show maximum CNR between liver-spleen (metastases) and to choose a better sequence for detecting metastases. CNR in the RARE sequence was more than in the MSSE sequence.
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Affiliation(s)
- F Jafari
- Department of Medical Physics, Tehran Medical Sciences University, Iran.
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Kim TK, Lee HJ, Jang HJ, Kim AY, Han JK, Choi BI. T2-weighted breath-hold MRI of the liver at 1.0 T: comparison of turbo spin-echo and HASTE sequences with and without fat suppression. J Magn Reson Imaging 1998; 8:1213-8. [PMID: 9848731 DOI: 10.1002/jmri.1880080606] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. Breath-hold turbo SE imaging with fat suppression showed the highest CNR for cystic lesions and the best lesion conspicuity for cystic and solid lesions among the four sequences. For solid lesions, there was no significant difference of lesion-to-liver CNR between them. HASTE sequence was superior to turbo SE sequences in terms of motion artifacts; however, the usefulness for evaluating focal hepatic lesions was limited compared with turbo SE sequence with fat suppression. Addition of fat suppression was not helpful for HASTE imaging because of decreased lesion conspicuity and extrahepatic details without the advantage of reducing motion artifacts. This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.
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Affiliation(s)
- T K Kim
- Department of Radiology, Seoul National University College of Medicine, University Hospital, Korea
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Gryspeerdt S, Van Hoe L, Bosmans H, Baert AL, Vergote I, Marchal G. T2-weighted MR imaging of the uterus: comparison of optimized fast spin-echo and HASTE sequences with conventional fast spin-echo sequences. AJR Am J Roentgenol 1998; 171:211-5. [PMID: 9648791 DOI: 10.2214/ajr.171.1.9648791] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE Our objective was to compare the value of a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence with optimized fast spin-echo and conventional fast spin-echo techniques in evaluation of the uterus. SUBJECTS AND METHODS Optimized fast spin-echo imaging was compared with fast spin-echo and HASTE imaging, for both image quality and ability to assess the zonal anatomy of the uterus, in 40 volunteers. In optimized fast spin-echo imaging, the imaging time was reduced using partial-Fourier reconstruction, reducing the echo spacing, and increasing the echo train length. RESULTS HASTE imaging offered the least motion artifact of all techniques. On optimized fast spin-echo imaging, motion artifacts were moderate to severe in 10% of patients. On fast spin-echo imaging, motion artifacts were moderate to severe in 40% of patients. Optimized fast spin-echo imaging was superior to the other two techniques in terms of anatomic sharpness and overall image quality. CONCLUSION Although HASTE imaging offers the unique feature of providing images free of motion artifacts, optimized fast spin-echo imaging appears to be the preferred technique for T2-weighted imaging of the uterus.
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Affiliation(s)
- S Gryspeerdt
- Service of Radiology, University Hospitals Gasthuisberg, Leuven, Belgium
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Coates GG, Borrello JA, McFarland EG, Mirowitz SA, Brown JJ. Hepatic T2-weighted MRI: a prospective comparison of sequences, including breath-hold, half-Fourier turbo spin echo (HASTE). J Magn Reson Imaging 1998; 8:642-9. [PMID: 9626880 DOI: 10.1002/jmri.1880080319] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The purpose of this study was to quantitatively compare the hepatic contrast characteristics of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences with breath-hold T2-weighted images acquired with half-Fourier turbo spin echo (HASTE). Forty-five patients were examined with a phased-array surface coil. Nineteen patients had focal hepatic lesions, including eight malignant tumors, 10 cavernous hemangiomas, and one hepatic adenoma. Twenty-six patients had no focal hepatic lesions. T2-weighted images with comparable TE were acquired with CSE, FSE, and HASTE pulse sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for liver, spleen, and lesions were measured. FSE demonstrated significantly better quantitative performance than CSE for liver-spleen CNR (P .0084). No statistically significant difference was demonstrated between FSE and CSE for liver or spleen SNR. FSE demonstrated clear scan time and resolution advantages over CSE. HASTE performed significantly poorer than CSE and FSE for liver-spleen CNR (P < .0001), liver SNR (P = .0002 for CSE and P < .0001 for FSE), and spleen SNR (P < .0001). Optimized FSE images with a short echo train length performed comparably to CSE images of equivalent TE. Liver-lesion CNR was suppressed on HASTE images, suggesting that long echo train length FSE sequences could diminish solid lesion detection compared to CSE and short echo train length FSE.
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Affiliation(s)
- G G Coates
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Abstract
This article reviews the currently available MR imaging techniques that are useful for the detection and characterization of focal and diffuse liver pathology. The implementation and clinical utility of various T1-weighted, T2-weighted, T2*-weighted, and MR angiographic sequences are described.
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Affiliation(s)
- E S Siegelman
- Department of Radiology, Hospital of the University of Pennsylvania, University of Pennsylvania Medical Center, Philadelphia, USA
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Mammone JF, Siegelman ES, Outwater EK. Magnetic resonance imaging of the pancreas and biliary tree. Semin Ultrasound CT MR 1998; 19:35-52. [PMID: 9503519 DOI: 10.1016/s0887-2171(98)90023-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
MRI of the pancreas and bile ducts is becoming more widely used due to recent advances in surface coils, breath-hold imaging techniques, and magnetic resonance cholangiopancreatography (MRCP). MRI provides a comprehensive and accurate examination for the detection, staging, and characterization of a variety of developmental, inflammatory, and neoplastic processes that involve the pancreas.
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Affiliation(s)
- J F Mammone
- Department of Diagnostic Radiology and Nuclear Medicine, UMDNJ, Robert Wood Johnson Medical School, Cooper Hospital-University Medical Center, Camden 08103, USA
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Affiliation(s)
- J A Soto
- Department of Radiology, Boston Medical Center, MA 02118, USA
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Affiliation(s)
- D J Lomas
- Department of Radiology, Addenbrooke's Hospital, Cambridge, UK
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Jara H, Soto JA, Yu B, Hentzen PC, van Yperen GH, Yucel EK. Multisection T1-weighted hybrid-RARE: a pulse sequence for MR imaging of the entire liver during suspended respiration. Magn Reson Med 1996; 36:767-74. [PMID: 8916028 DOI: 10.1002/mrm.1910360516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
It is shown that the maximum average-data-collection-speed (ADCS) of multisection 2D hybrid-RARE sequences is independent of TR and TEeff, and a monotonically increasing function of echo-train-length (ETL). This result was used in the design of an optimized T1-weighted hybrid-RARE sequence that produces 20 images of the abdomen in 31 s divided into four breath-hold periods. The resulting ADCS is 58 lines in k-space per second. Twenty-four subjects (2 healthy volunteers and 22 patients) were imaged with a protocol that also included: (a) breath-hold T1-weighted FLASH which acquires data at 34 lines in k-space per second (49 s scan time), and (b) T1-weighted conventional spin-echo (9:44 minutes scan time) with respiratory compensation. The experiments show that this T1-weighted-hybrid-RARE sequence has: (1) a level of T1 weighting that is comparable with the conventional sequences, (2) very low vulnerability to susceptibility artifacts, (3) high data acquisition efficiency, and (4) higher SNR than T1-weighted-FLASH. In conclusion, the T1-weighted-hybrid-RARE sequence described herein is an efficacious and reproducible technique for rapid imaging of the upper abdomen during suspended respiration.
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Affiliation(s)
- H Jara
- Boston City Hospital Center for MRI, Boston University School of Medicine, Massachusetts, USA
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22
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Ichikawa T, Nitatori T, Hachiya J, Mizutani Y. Breath-held MR cholangiopancreatography with half-averaged single shot hybrid rapid acquisition with relaxation enhancement sequence: comparison of fast GRE and SE sequences. J Comput Assist Tomogr 1996; 20:798-802. [PMID: 8797916 DOI: 10.1097/00004728-199609000-00022] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE Our goal was to determine whether half-averaged single shot hybrid rapid acquisition with relaxation enhancement (single shot hybrid RARE) sequence can improve image quality, duct conspicuity, signal intensity ratio (SIR), and contrast-to-noise ratio (CNR) of MR cholangiopancreatography (MRCP) by comparing it with two other MRCP sequences: fast SE (FSE) and contrast-enhanced Fourier-acquired steady-state technique (CE-FAST). METHOD MRCP with three sequences was obtained in 46 people (10 volunteers, 36 patients with pancreatobiliary disease). Overall image quality and duct conspicuity were graded. SIR and CNR were also measured. RESULTS Overall image quality was graded excellent or good in all 46 patients (100%) with single shot hybrid RARE, in 38 of 46 (83%) with FSE, and in 5 of 46 (11%) with CE-FAST. Duct conspicuity was the best in single shot hybrid RARE statistically. SIR was the highest in FSE, while CNR was highest statistically in single shot hybrid RARE of three sequences. CONCLUSION Single shot hybrid RARE can provide consistently higher quality MRCP than FSE and CE-FAST because sequential images by single shot hybrid RARE minimize respiratory, bowel, and cardiac motion artifacts.
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Affiliation(s)
- T Ichikawa
- Department of Radiology, Kyorin University School of Medicine, Tokyo, Japan
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23
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Semelka RC, Kelekis NL, Thomasson D, Brown MA, Laub GA. HASTE MR imaging: description of technique and preliminary results in the abdomen. J Magn Reson Imaging 1996; 6:698-9. [PMID: 8835965 DOI: 10.1002/jmri.1880060420] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
HASTE (Half fourier Single-shot Turbo spin-Echo) is a single-section T2-weighted sequence that acquires images in less than 1 second. Images are breathing independent and possess a variety of other features useful for imaging the abdomen. The design of this technique is described. Clinical studies of 38 consecutive patients were performed using this technique. HASTE images were considered good in 28 and fair in 10 patients, including five patients who could not suspend respiration. Definition of liver and bowel was particularly clear.
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Affiliation(s)
- R C Semelka
- Department of Radiology, University of North Carolina, Chapel Hill 27599-7510, USA
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24
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Carpenter KD, Macaulay SE, Schulte SJ, Obregon RG, Nelson RC, Simon HE, Schmiedl UP. MR of focal liver lesions: comparison of breath-hold and non-breath-hold hybrid RARE and conventional spin-echo T2-weighted pulse sequences. J Magn Reson Imaging 1996; 6:596-602. [PMID: 8835952 DOI: 10.1002/jmri.1880060407] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To compare liver lesion detection rates, tissue signal and noise data, and qualitative parameters for breath-hold (BH) and non-breath-hold (NBH) hybrid rapid acquisition with relaxation enhancement (RARE) and conventional spin-echo (CSE) T2-weighted (CSE-T2) MR sequences, 20 patients were imaged using all three sequences. Lesion detection rates were 73.5% for the CSE-T2 sequence and 81.1% and 88.6% for the BH-RARE and NBH-RARE sequences, respectively (P = .027). Mean lesion-to-liver signal-difference-to-noise ratio for the NBH-RARE sequence was 14.0 +/- 11.5, significantly greater than 9.8 +/- 7.8 obtained for the BH-RARE sequence (P = .050) and 9.0 +/- 6.2 obtained for the CSE-T2 sequence (P = .015). The NBH-RARE sequence demonstrated fewer artifacts and greater overall image quality compared to the CSE-T2 sequence. The NBH-RARE sequence is a useful alternative to the liver signal-difference-to-noise ratio and lesion detection rate and better overall image quality.
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Affiliation(s)
- K D Carpenter
- Department of Radiology, Veterans Administration Medical Center, Seattle, WA 98108, USA
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25
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Gauger J, Holzknecht NG, Lackerbauer CA, Sittek H, Fiedler KE, Petsch R, Reiser M. Breathhold imaging of the upper abdomen using a circular polarized-array coil: comparison with standard body coil imaging. MAGMA (NEW YORK, N.Y.) 1996; 4:93-104. [PMID: 8875395 DOI: 10.1007/bf01772516] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Current studies emphasize the use of array coils to decrease noise and increase the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). We applied T1-weighted and T2-weighted standard nonbreathhold spin echo (SE) sequences and T1-weighted FLASH, TurboFLASH, T2-weighted spin-echo time (TSE), and heavily T2-weighted half Fourier acquisition single-shot TSE (HASTE) sequences during breathhold for abdominal imaging in 15 normal volunteers. The breathhold scans were performed using both a standard coil and a circular polarized array coil. We analyzed the signal intensity (SI), SNR, and CNR of abdominal organs in all sequences. SNRs increased in all cases by an overall factor of approximately 3 due to an 8% increase in overall SIs and a 50% decrease in noise when applying the array coil. Although the array-coil FLASH sequence performed at least as well as the respective SE sequence, the SNRs of the array-coil TurboFLASH, TSE breathhold, and HASTE sequences were generally lower. We conclude that array-coil imaging significantly improves fast imaging of the abdomen.
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Affiliation(s)
- J Gauger
- Department of Diagnostic Radiology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany
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26
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Lencioni R, Mascalchi M, Paolicchi A, Zampa V. Breath-hold spin-echo MR imaging for evaluation of dynamic enhancement of native and treated hepatocellular carcinoma after intravenous Gd-DTPA administration. MAGMA (NEW YORK, N.Y.) 1995; 3:151-6. [PMID: 8749733 DOI: 10.1007/bf01771700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Using a simple modification of a standard spin-echo sequence which enable acquisition of three breath-hold images in 15 s, dynamic enhancement of 30 histologically proven hepatocellular carcinomas (17 native tumors, 6 completely necrotic tumors after nonsurgical treatments, and 7 tumors with viable and necrotic portions) after intravenous injection of gadolinium-DTPA was evaluated. Native hepatocellular carcinomas and viable portions in treated nodules showed elective enhancement in images obtained 40 s after contrast injection. Contrast between these lesions and the normal liver decreased thereafter. No contrast uptake was seen in entirely necrotic nodules and necrotic portions of treated nodules. Because of the capability to demonstrate the elective arterial blood supply typical of hepatocellular carcinoma, breath-hold T1-weighted spin-echo sequence should replace conventional T1-weighted images for the evaluation of intravenously administered gadolinium-DTPA enhancement of this tumor before and after nonsurgical treatments.
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Affiliation(s)
- R Lencioni
- Department of Radiology, University of Pisa, Italy
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Abstract
Strong fat signal in regions where a large susceptibility difference exists, for instance at the interface between air and tissue near the maxillary sinus, may not be eliminated by currently available fat suppression techniques without sacrificing the overall quality of the images. In this article, we show that this fat signal, which appears as a susceptibility artifact, can be significantly reduced by using an optimized presaturation pulse with sharp edges and a broad bandwidth, while causing minimal disturbance of the water signal. Several optimized presaturation pulses can be reproduced by the Fourier coefficients provided in the Appendix.
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Affiliation(s)
- J Mao
- Department of Radiology, University of Florida, Gainesville 32610, USA
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28
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Yoshimitsu K, Varma DG, Jackson EF. Unsuppressed fat in the right anterior diaphragmatic region on fat-suppressed T2-weighted fast spin-echo MR images. J Magn Reson Imaging 1995; 5:145-9. [PMID: 7766975 DOI: 10.1002/jmri.1880050205] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The authors retrospectively evaluated magnetic resonance images of the abdomen obtained in 52 consecutive patients. All cases included fast spin-echo (FSE) T2-weighted images acquired with a frequency-selective fat saturation technique. All imaging was performed with a 1.5-T unit. In 42 patients (81%), fat was not suppressed in the right anterior diaphragmatic region on the T2-weighted FSE images with fat suppression. In 11 (26%) of these 42 patients, subcutaneous fat adjacent to the unsuppressed anterior diaphragmatic fat was well suppressed. Hence, the fat in the diaphragmatic region mimicked fluid or peritoneal implants. The cause of the artifact appears to be the juxtaposition of liver, fat, and lung parenchymal air within a small anatomic space, creating a localized inhomogeneity of the magnetic field and susceptibility effects. Radiologists should be aware of this phenomenon to prevent confusion of an artifact with fluid or neoplasms.
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Affiliation(s)
- K Yoshimitsu
- Department of Diagnostic Radiology, University of Texas, M. D. Anderson Cancer Center, Houston 77030, USA
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Mitchell DG, Winston CB, Outwater EK, Ehrlich SM. Delineation of pancreas with MR imaging: multiobserver comparison of five pulse sequences. J Magn Reson Imaging 1995; 5:193-9. [PMID: 7766982 DOI: 10.1002/jmri.1880050215] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The authors compared five magnetic resonance (MR) imaging pulse sequences for their ability to depict the pancreas in 59 patients, each evaluated with at least two of the five sequences. Focal pancreatic carcinomas were present in eight patients. The five sequences were T1-weighted spin echo (T1-SE), fat-suppressed T1-SE (T1-FS), T1-weighted gradient echo (T1-GRE), T2-weighted SE (T2-SE), and T2-weighted fast spin echo (T2-FSE). Using repeated-measures analysis, three blinded observers independently reviewed 198 separate MR imaging series and rated them on a 5-point scale with regard to image quality and depiction of pancreatic borders and the number of sections containing pancreatic and common bile ducts. The most superior and most inferior sections containing pancreas were recorded for each sequence in each patient. The results were compared with analysis of variance, and interobserver agreement was measured with the intraclass correlation coefficient (ICC). For image quality, all sequences were rated good to excellent, with the T1-SE sequence having the highest rating. For clarity of pancreatic borders, however, the T1-FS sequence was rated significantly higher (P < .006) than the other sequences; the T2-SE sequence was least satisfactory. Common bile and pancreatic ducts were seen in the most sections with the T2-FSE sequence. There were no significant differences regarding identification of the most superior and inferior sections containing pancreas, and the ICC was high (.91-.97) for all sequences. For detecting focal carcinomas, no single pulse sequence was sufficient.
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Affiliation(s)
- D G Mitchell
- Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
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