Magnetic resonance imaging of brain tumors: measurement of T1. Work in progress.

Araki, Tsutomu; Inouye, T.; Suzuki, Hiroharu; Machida, Tohru; M, Iio

doi:10.1148/radiology.150.1.6689793

Cited by 75 publications

(15 citation statements)

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“…Note that Oo in Eq. [2] is only a rough, system-calibrated guess of the flip-angle, whereas a,,a(r)B,, is the actual flip-angle experienced at position r.…”

Section: Theorymentioning

confidence: 99%

Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Venkatesan

Lin

Haacke

1998

Magnetic Resonance in Med

133

178

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A method is presented for the accurate extraction of relative spin-density (rho0) and spin-lattice relaxation time (T1) in the presence of RF-field inhomogeneities and flip-angle miscalibration. The method requires collecting images at several flip-angles with a three-dimensional, spoiled steady-state, gradient-echo imaging sequence. Results show that the predominant effect of an overestimated flip-angle is to shift the T1 estimate to a higher value, whereas reductions in the normalized RF-field from unity cause rho0 and T1 distributions to be skewed toward lower values. Phantom and in vivo results demonstrate that the proposed method overcomes both of these systematic errors. The method was shown to be valid for up to a 50% reduction in RF sensitivity. A self-consistency argument was used to validate the absence of systematic errors in the extracted rho0 and T1 values over a large number of voxels. This made it possible to obtain a very precise estimate of muscle T1 at 1.5 T, yielding a 95% confidence interval of (1077.7 +/- 3.5) ms.

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“…Note that Oo in Eq. [2] is only a rough, system-calibrated guess of the flip-angle, whereas a,,a(r)B,, is the actual flip-angle experienced at position r.…”

Section: Theorymentioning

confidence: 99%

Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Venkatesan

Lin

Haacke

1998

Magnetic Resonance in Med

133

178

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show abstract

“…12 in whom the interval between the first CT examination with contrast medium of progression, in terms of the extent of the low attenuating area, or of alteration of the signs of mild expansion that was seen in the primary CT examination without contrast medium. Table 4 Signal intensity values and ratio of signal intensity between tumour and white matter (T/W) in high-grade astrocytomas (cases [1][2][3][4][5], low-grade astrocytomas (cases 8 In cases 8 and 13, where no enhancement was noted after administration of contrast medium on MR or CT, the ROI was placed according to the area of methionine accumulation in PET.…”

Section: Methodsmentioning

confidence: 99%

“…Although several authors (1,5,24) have found abnormalities in T1 and T2 relaxation times in intracranial tumours, the values alone have not been sufficient for separating tumour tissue from oedema or for distinguishing benign from malignant lesions. The need for a contrast agent (marker of blood-brain-barrier (BBB) disruption; 29) in MR that could cause changes in T1 and T2, facilitating tumour/oedema discrimination, was pointed out (3).…”

mentioning

confidence: 98%

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

Tovi¹,

Lilja²,

Bergström³

et al. 1990

Acta Radiol

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Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using llC-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas with increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I-II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the Tl weighted SE sequences used was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the Tl weighted SE sequences. A greater increase in signal intensity in Tl weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.

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“…In 1984, the first two articles (48,49) dealing with MR imaging of brain tumors appeared in Radiology. In the first report (48), T1 measurements of brain masses were performed, and the authors found that astrocytomas had the longest T1 and lipomas had the shortest. The second article (49) was a comparison between the then well-established CT and MR imaging.…”

Section: Early Physiologic Tumor Neuroimagingmentioning

confidence: 99%

History and Evolution of Brain Tumor Imaging: Insights throughRadiology

Castillo¹

2014

Radiology

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This review recounts the history of brain tumor diagnosis from antiquity to the present and, indirectly, the history of neuroradiology. Imaging of the brain has from the beginning held an enormous interest because of the inherent difficulty of this endeavor due to the presence of the skull. Because of this, most techniques when newly developed have always been used in neuroradiology and, although some have proved to be inappropriate for this purpose, many were easily incorporated into the specialty. The first major advance in modern neuroimaging was contrast agent-enhanced computed tomography, which permitted accurate anatomic localization of brain tumors and, by virtue of contrast enhancement, malignant ones. The most important advances in neuroimaging occurred with the development of magnetic resonance imaging and diffusion-weighted sequences that allowed an indirect estimation of tumor cellularity; this was further refined by the development of perfusion and permeability mapping. From its beginnings with indirect and purely anatomic imaging techniques, neuroradiology now uses a combination of anatomic and physiologic techniques that will play a critical role in biologic tumor imaging and radiologic genomics.

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Magnetic resonance imaging of brain tumors: measurement of T1. Work in progress.

Cited by 75 publications

References 0 publications

Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

History and Evolution of Brain Tumor Imaging: Insights throughRadiology

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Magnetic resonance imaging of brain tumors: measurement of T1. Work in progress.

Cited by 75 publications

References 0 publications

Accurate determination of spin‐density and T1 in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Accurate determination of spin‐density and T1 in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

History and Evolution of Brain Tumor Imaging: Insights throughRadiology

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Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration

Accurate determination of spin‐density and T₁ in the presence of RF‐field inhomogeneities and flip‐angle miscalibration