کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5407774 | 1393230 | 2006 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Experimental validation of a T2Ï transverse relaxation model using LASER and CPMG acquisitions
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
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چکیده انگلیسی
The transverse relaxation rate (R2 = 1/T2) of many biological tissues are altered by endogenous magnetized particles (i.e., ferritin, deoxyhemoglobin), and may be sensitive to the pathological progression of neurodegenerative disorders associated with altered brain-iron stores. R2 measurements using Carr-Purcell-Meiboom-Gill (CPMG) acquisitions are sensitive to the refocusing pulse interval (2Ïcp), and have been modeled as a chemical exchange (CE) process, while R2 measurements using a localization by adiabatic selective refocusing (LASER) sequence have an additional relaxation rate contribution that has been modeled as a R2Ï process. However, no direct comparison of the R2 measured using these two sequences has been described for a controlled phantom model of magnetized particles. The three main objectives of this study were: (1) to compare the accuracy of R2 relaxation rate predictions from the CE model with experimental data acquired using a conventional CPMG sequence, (2) to compare R2 estimates obtained using LASER and CPMG acquisitions, and (3) to determine whether the CE model, modified to account for R2Ï relaxation, adequately describes the R2 measured by LASER for a full range of Ïcp values. In all cases, our analysis was confined to spherical magnetic particles that satisfied the weak field regime. Three phantoms were produced that contained spherical magnetic particles (10 μm diameter polyamide powders) suspended in Gd-DTPA (1.0, 1.5, and 2.0 mmol/L) doped gel. Mono-exponential R2 measurements were made at 4 T as a function of refocusing pulse interval. CPMG measurements of R2 agreed with CE model predictions while significant differences in R2 estimates were observed between LASER and CPMG measurements for short Ïcp acquisitions. The discrepancy between R2 estimates is shown to be attributable to contrast enhancement in LASER due to T2Ï relaxation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetic Resonance - Volume 181, Issue 1, July 2006, Pages 35-44
Journal: Journal of Magnetic Resonance - Volume 181, Issue 1, July 2006, Pages 35-44
نویسندگان
Simona Nikolova, Chris V. Bowen, Robert Bartha,