MRI relaxometry: methods and applications

Carneiro, Antônio Adilton Oliveira; Vilela, G. R.; Araújo, Dráulio Barros de; Baffa, Oswaldo

doi:10.1590/s0103-97332006000100005

Cited by 57 publications

(39 citation statements)

References 12 publications

(21 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Currently, multispin-echo (MSE) sequences are commonly employed (9). In this study, the data were collected using 8 different TEs.…”

Section: Discussionmentioning

confidence: 99%

“…In general, T2 maps and tissue T2 relaxation times are obtained by scans with long repetition times (TRs) and two or more echo times (TEs). Several studies have used T2 mapping to measure the T2 relaxation time in benign and malignant breast lesions to determine the potential role of this method in the differentiation of benign and malignant breast lesions, as well as monitoring the response of breast tumors to neoadjuvant chemotherapy (9-12). In addition, there is one study using the T2 relaxation time to predict the response to NAC (10).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Changes of T2 Relaxation Time From Neoadjuvant Chemotherapy in Breast Cancer Lesions

et al. 2016

View full text Add to dashboard Cite

BackgroundNeoadjuvant chemotherapy (NAC) is generally an effective method of reducing locally advanced malignant breast lesions before surgery; assessing the tumor response to NAC is crucial for patient management. T2 relaxation times can reflect biological state of lesions, may prove useful to assess the response to NAC.ObjectivesTo investigate the lesion T2 relaxation times change in breast cancer neoadjuvant chemotherapy (NAC).Patients and MethodsIn total, 26 patients underwent NAC. Magnetic resonance imaging (MRI) T2 mapping was performed before and after NAC. The T2 relaxation times were obtained by using Functool software on an AW 43 workstation. The treatment response was assessed according to the pathological response classification. We aimed to analyze the changes in the T2 relaxation times before and after NAC as well as to study the relationship between the response and the lesion T2 relaxation times after NAC.ResultsIn 26 cases with NAC, the mean lesion T2 relaxation time before NAC was 81.34 ± 13.68 ms, compared with 64.50 ± 8.71 ms after NAC. Significant differences in the lesion T2 relaxation times existed between the pre- and post-NAC (P < 0.001) ; based on the pathology results, the mean lesion T2 relaxation times in 23 of the 26 responders (63.18 ± 8.37 ms) was shorter than in 3 of the 26 nonresponders (74.62 ± 2.32 ms) after NAC (P = 0.029).ConclusionIn breast cancer after NAC, the lesion T2 relaxation time was reduced in the responders, and this finding is potentially useful to assess the response to NAC.

show abstract

“…Currently, multispin-echo (MSE) sequences are commonly employed (9). In this study, the data were collected using 8 different TEs.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes of T2 Relaxation Time From Neoadjuvant Chemotherapy in Breast Cancer Lesions

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The other pulse sequence parameters were kept constant across the seven images and included TR=3500ms, flip angle = 90°, and slice thickness = 3mm, providing an in-plane resolution 0.9766mm × 0.9766mm. The transverse relaxation time (T2-relaxation) was estimated by modeling the observed MRI signal as 34 …”

Section: Methodsmentioning

confidence: 99%

The effects of changing water content, relaxation times, and tissue contrast on tissue segmentation and measures of cortical anatomy in MR images

Bansal

Hao

Liu

et al. 2013

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Water content is the dominant chemical compound in the brain and it is the primary determinant of tissue contrast in magnetic resonance (MR) images. Water content varies greatly between individuals, and it changes dramatically over time from birth through senescence of the human life span. We hypothesize that the effects that individual- and age-related variations in water content have on contrast of the brain in MR images also has important, systematic effects on in vivo, MRI-based measures of regional brain volumes. We also hypothesize that changes in water content and tissue contrast across time may account for age-related changes in regional volumes, and that differences in water content or tissue contrast across differing neuropsychiatric diagnoses may account for differences in regional volumes across diagnostic groups. We demonstrate in several complementary ways that subtle variations in water content across age and tissue compartments alter tissue contrast, and that changing tissue contrast in turn alters measures of the thickness and volume of the cortical mantle: (1) We derive analytic relations describing how age-related changes in tissue relaxation times produce age-related changes in tissue gray-scale intensity values and tissue contrast; (2) We vary tissue contrast in computer-generated images to assess its effects on tissue segmentation and volumes of gray matter and white matter; and (3) We use real-world imaging data from adults with either Schizophrenia or Bipolar Disorder and age- and sex-matched healthy adults to assess the ways in which variations in tissue contrast across diagnoses affects group differences in tissue segmentation and associated volumes. We conclude that in vivo MRI-based morphological measures of the brain, including regional volumes and measures of cortical thickness, are a product of, or at least are confounded by, differences in tissue contrast across individuals, ages, and diagnostic groups, and that differences in tissue contrast in turn likely derive from corresponding differences in water content of the brain across individuals, ages, and diagnostic groups.

show abstract

“…These values, correlated with micro structural characteristics of tissues, provide absolute, tissue specific, field strength and machine independent T2 values and are highly sensitive to e.g. iron content (Carneiro et al, 2006). In this study, we investigated whether a decrease of T2 relaxation times in the subthalamic nucleus (STN) can be used as surrogate marker for target selection in DBS.…”

Section: Introductionmentioning

confidence: 99%

T2-relaxometry predicts outcome of DBS in idiopathic Parkinson's disease

Lönnfors-Weitzel

Weitzel

Slotboom

et al. 2016

NeuroImage: Clinical

View full text Add to dashboard Cite

IntroductionDeep brain stimulation (DBS) nowadays is a well-established treatment of motor symptoms in Parkinson's disease. The subthalamic nucleus (STN) is a common target for DBS, because motor improvements have been shown to be superior to best medical therapy, if DBS electrodes have been appropriately positioned. DBS target identification can be assisted by MRI beyond structural imaging by spatially resolved measurement of T2-relaxation times (T2r).AimWe pose the question, whether T2r of the STN is linked to the severity of the disease and whether outcome of DBS may be correlated to an asymmetric manifestation of the disease. Further, we investigated if abnormal T2r in the STN may be predictive for outcome of DBS.MethodsTwelve patients underwent preoperative MR imaging including a multi echo relaxometry sequence (3 Tesla, Siemens Medical Systems, Erlangen, Germany) ahead of DBS. T2r were determined for STN, substantia nigra (SN), red nucleus (RN) and centrum semiovale (CSO). Unified Parkinson's disease Rating Scale (UPDRS) scores were tested before and after DBS. Patients' T2r and deduced values representing left-right asymmetry of measurements were correlated with UPDRS scores and measures for outcome of DBS. Furthermore, patients' T2r were compared with T2r measurements in 12 healthy controls (HC).ResultsPatients' T2r for SN (mean 45.4 ms ± 4.4 ms) and STN (mean 56.4 ms ± 3.8 ms) were significantly shorter than T2r in HCs for SN (mean 60.7 ± 4.6) and STN (mean 66.1 ms ± 4.0 ms). While no mean T2r asymmetry was found in the SN, patients' mean T2r for STN showed a weakened left-right correlation (Pearson correlation coefficient 0.19 versus 0.72 in HC) indicating asymmetric degeneration. T2r asymmetry was not linked to the more severely affected hemisphere.The respective lower T2r within the left or right target region was significantly correlated to the outcome in terms of UPDRS III improvement in “off” state (Pearson correlation 0.82 corresponding to p ≪ 0.01). Patients with T2r of STN lower than 50 ms showed no response to DBS in the UPDRS.The maximum T2r for SN correlated to the improvement between UPDRS “off” minus and “on” (Dopamine response) but failed to predict DBS outcome.ConclusionsThe lower boundaries of T2r in the STN predict motor outcome in DBS. T2r asymmetry in the STN is not associated with increased clinical symptoms, but with response to therapy. Thus, patients with very low T2r may be inappropriate candidates for DBS.

show abstract

MRI relaxometry: methods and applications

Cited by 57 publications

References 12 publications

Changes of T2 Relaxation Time From Neoadjuvant Chemotherapy in Breast Cancer Lesions

Changes of T2 Relaxation Time From Neoadjuvant Chemotherapy in Breast Cancer Lesions

The effects of changing water content, relaxation times, and tissue contrast on tissue segmentation and measures of cortical anatomy in MR images

T2-relaxometry predicts outcome of DBS in idiopathic Parkinson's disease

Contact Info

Product

Resources

About