Determining the effect of water temperature on the T1 and T2 relaxation times of the lung tissue at 9.4 T MRI: A drowning mouse model

Several circumstances may explain the great variation in reported proton T1 and T2 relaxation times usually seen. This study was designed to evaluate the accuracy of relaxation time measurements by magnetic resonance imaging (MRI) operating at 1.5 tesla. Using a phantom of nine boxes with different concentrations of CuSO4 and correlating the calculated T1 and T2 values with reference values obtained by two spectrometers (corrected to MRI-proton frequency=64 MHz) we found a maximum deviation of about 10 per cent. Measurements performed on a large water phantom in order to evaluate the homogeneity in the imaging plane showed a variation of less than 10 per cent within 10 cm from the centre of the magnet in all three imaging planes. Changing the gradient field strength apparently had no influence on the T2 values recorded. Consequently diffusion processes seem without significance. It is concluded that proton T1 and T2 relaxation times covering the majority of the biologic range can be measured by MRI with an overall accuracy of 5 to 10 per cent. Quality control studies along the lines indicated in this study are recommended.

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Disease Detection By MR Imaging: T1 And T2 Relaxation Times

Cell Function and Disease ◽

10.1007/978-1-4613-0813-3_37 ◽

1988 ◽

pp. 415-420

Author(s):

Luis E. Todd ◽

Guillermo Elizondo ◽

Ralph Weissleder

Keyword(s):

Mr Imaging ◽

Relaxation Times ◽

Disease Detection ◽

T2 Relaxation ◽

T1 And T2

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The Effect of Intraventricular Hemorrhage on Brain Development in Premature Infants: A Synthetic MRI Study

Frontiers in Neurology ◽

10.3389/fneur.2021.721312 ◽

2021 ◽

Vol 12 ◽

Author(s):

Chunxiang Zhang ◽

Xin Zhao ◽

Meiying Cheng ◽

Kaiyu Wang ◽

Xiaoan Zhang

Keyword(s):

Relaxation Time ◽

Premature Infants ◽

Intraventricular Hemorrhage ◽

Brain Volume ◽

Relaxation Times ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

T1 And T2 ◽

The Brain ◽

Synthetic Mri

Objectives: Synthetic MRI can obtain multiple parameters in one scan, including T1 and T2 relaxation time, proton density (PD), brain volume, etc. This study aimed to investigate the parameter values T1 and T2 relaxation time, PD, and volume characteristics of intraventricular hemorrhage (IVH) newborn brain, and the ability of synthetic MRI parameters T1 and T2 relaxation time and PD to diagnose IVH.Materials and methods: The study included 50 premature babies scanned with conventional and synthetic MRI. Premature infants were allocated to the case group (n = 15) and NON IVH (n = 35). The T1, T2, PD values, and brain volume were obtained by synthetic MRI. Then we assessed the impact of IVH on these parameters.Results: In the posterior limbs of the internal capsule (PLIC), genu of the corpus callosum (GCC), central white matter (CWM), frontal white matter (FWM), and cerebellum (each p < 0.05), the T1 and T2 relaxation times of the IVH group were significantly prolonged. There were significant differences also in PD. The brain volume in many parts were also significantly reduced, which was best illustrated in gray matter (GM), cerebrospinal fluid and intracranial volume, and brain parenchymal fraction (BPF) (each p < 0.001, t = −5.232 to 4.596). The differential diagnosis ability of these quantitative values was found to be excellent in PLIC, CWM, and cerebellum (AUC 0.700–0.837, p < 0.05).Conclusion: The quantitative parameters of synthetic MRI show well the brain tissue characteristic values and brain volume changes of IVH premature infants. T1 and T2 relaxation times and PD contribute to the diagnosis and evaluation of IVH.

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Reliability of Synthetic Brain MRI for Assessment of Ischemic Stroke with Phantom Validation of a Relaxation Time Determination Method

Journal of Clinical Medicine ◽

10.3390/jcm9061857 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1857

Author(s):

Chia-Wei Li ◽

Ai-Ling Hsu ◽

Chi-Wen C. Huang ◽

Shih-Hung Yang ◽

Chien-Yuan Lin ◽

...

Keyword(s):

Ischemic Stroke ◽

Relaxation Time ◽

Brain Mri ◽

Relaxation Times ◽

Onset Time ◽

Magnetic Resonance Images ◽

Diagnostic Tools ◽

Cupric Sulfate ◽

T2 Relaxation ◽

T1 And T2

The reliability of relaxation time measures in synthetic magnetic resonance images (MRIs) of homemade phantoms were validated, and the diagnostic suitability of synthetic imaging was compared to that of conventional MRIs for detecting ischemic lesions. Phantoms filled with aqueous cupric-sulfate (CuSO4) were designed to mimic spin-lattice (T1) and spin-spin (T2) relaxation properties and were used to compare their accuracies and stabilities between synthetic and conventional scans of various brain tissues. To validate the accuracy of synthetic imaging in ischemic stroke diagnoses, the synthetic and clinical scans of 18 patients with ischemic stroke were compared, and the quantitative contrast-to-noise ratios (CNRs) were measured, using the Friedman test to determine significance in differences. Results using the phantoms showed no significant differences in the interday and intersession synthetic quantitative T1 and T2 values. However, between synthetic and referenced T1 and T2 values, differences were larger for longer relaxation times, showing that image intensities in synthetic scans are relatively inaccurate in the cerebrospinal fluid (CSF). Similarly, CNRs in CSF regions of stroke patients were significantly different on synthetic T2-weighted and T2-fluid-attenuated inversion recovery images. In contrast, differences in stroke lesions were insignificant between the two. Therefore, interday and intersession synthetic T1 and T2 values are highly reliable, and discrepancies in synthetic T1 and T2 relaxation times and image contrasts in CSF regions do not affect stroke lesion diagnoses. Additionally, quantitative relaxation times from synthetic images allow better estimations of ischemic stroke onset time, consequently increasing confidence in synthetic MRIs as diagnostic tools for ischemic stroke.

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Myocardial Mapping in Systemic Sarcoidosis: A Comparison of Two Measurement Approaches

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren ◽

10.1055/a-1174-0537 ◽

2020 ◽

Vol 193 (01) ◽

pp. 68-76

Author(s):

Darius Dabir ◽

Julian Luetkens ◽

Daniel Kuetting ◽

Jennifer Nadal ◽

Hans Heinz Schild ◽

...

Keyword(s):

T1 Mapping ◽

Tissue Characterization ◽

Cardiac Involvement ◽

T2 Mapping ◽

Relaxation Times ◽

Short Axis Slice ◽

T2 Relaxation ◽

Standard Mapping ◽

Systemic Sarcoidosis ◽

T1 And T2

Purpose To investigate if T1 and T2 mapping is able to differentiate between diseased and healthy myocardium in patients with systemic sarcoidosis, and to compare the standard mapping measurement (measurement within the whole myocardium of the midventricular short axis slice, SAX) to a more standardized method measuring relaxation times within the midventricular septum (ConSept). Materials and Methods 24 patients with biopsy-proven extracardiac sarcoidosis and 17 healthy control subjects were prospectively enrolled in this study and underwent CMR imaging at 1.5 T including native T1 and T2 mapping. Patients were divided into patients with (LGE+) and without (LGE–) cardiac sarcoidosis. T1 and T2 relaxation times were compared between patients and controls. Furthermore, the SAX and the ConSept approach were compared regarding differentiation between healthy and diseased myocardium. Results T1 and T2 relaxation times were significantly longer in all patients compared with controls using both the SAX and the ConSept approach (p < 0.05). However, LGE+ and LGE– patients showed no significant differences in T1 and T2 relaxation times regardless of the measurement approach used (ConSept/SAX) (p > 0.05). Direct comparison of ConSept and SAX T1 mapping showed high conformity in the discrimination between healthy and diseased myocardium (Kappa = 0.844). Conclusion T1 and T2 mapping may not only enable noninvasive recognition of cardiac involvement in patients with systemic sarcoidosis but may also serve as a marker for early cardiac involvement of the disease allowing for timely treatment. ConSept T1 mapping represents an equivalent method for tissue characterization in this population compared to the SAX approach. Further studies including follow-up examinations are necessary to confirm these preliminary results. Key Points: Citation Format

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