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Novel method for rapid, simultaneous T1, T*2, and proton density quantification
Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.ORCID-id: 0000-0002-6189-0807
Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.ORCID-id: 0000-0001-8661-2232
2007 (engelsk)Inngår i: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 57, nr 3, s. 528-537Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

An imaging method called “quantification of relaxation times and proton density by twin-echo saturation-recovery turbo-field echo” (QRAPTEST) is presented as a means of quickly determining the longitudinal T1 and transverse T relaxation time and proton density (PD) within a single sequence. The method also includes an estimation of the B1 field inhomogeneity. High-resolution images covering large volumes can be achieved within clinically acceptable times of 5–10 min. The range of accuracy for determining T1, T, and PD values is flexible and can be optimized relative to any anticipated values. We validated the experimental results against existing methods, and provide a clinical example in which quantification of the whole brain using 1.5 mm3 voxels was achieved in less than 8 min.

sted, utgiver, år, opplag, sider
2007. Vol. 57, nr 3, s. 528-537
Emneord [en]
Proton density mapping, Quantitative mri, Rapid quantification, T1 mapping, T2* mapping
HSV kategori
Identifikatorer
URN: urn:nbn:se:liu:diva-49979DOI: 10.1002/mrm.21165ISI: 000244657200010OAI: oai:DiVA.org:liu-49979DiVA, id: diva2:270875
Tilgjengelig fra: 2009-10-11 Laget: 2009-10-11 Sist oppdatert: 2019-06-14
Inngår i avhandling
1. Quantitative magnetic resonance in diffuse liver and neurological disease
Åpne denne publikasjonen i ny fane eller vindu >>Quantitative magnetic resonance in diffuse liver and neurological disease
2008 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Magnetic resonance (MR) has become one of the most important diagnostic tools in modern medicine. It provides superior soft tissue contrast compared to other imaging modalities, it is extremely flexible as it can be used to image all parts of the body, and it is considered to be safe for patients.

Today almost all MR is performed in a non-quantitative manner, only by comparing neighbouring tissue in the search for pathology. It is possible to quantify the MR-signals to its physical entities, but time consuming and complicated calibration procedures have prevented this in clinical routine.

In this work two different applications of quantitative MR-spectroscopy in diffuse liver and neurological disease, and a new rapid method for simultaneous quantification of proton density, T1 relaxation and T2* relaxation in MR-imaging are presented.

In Paper I, absolutely quantified phosphorus MR-spectroscopy was tested as a predictive tool in order to determine the degree of fibrosis on patients with diffuse liver disease. One group with steatosis and none to moderate inflammation (n=13), one group with severe fibrosis or cirrhosis (n=16), and one group of healthy volunteers (n=13) were included in the study.

Lower concentrations of PDE (p = 0.025), and a higher metabolic charge (AC) [42] (p < 0.001) were found in the cirrhosis group. A sensitivity and specificity of 81% and 69% respectively, were found for the discrimination between mild and advanced fibrosis using PDE concentrations, and 93% and 54% using AC. The results suggest PDE as a marker of liver fibrosis and AC as a potential clinically useful parameter in discriminating mild from advanced fibrosis.

In Paper II proton MR-spectroscopy was used to investigate if there were differences in the concentrations of the observable metabolites in normal appearing white matter in patients with clinically definite multiple sclerosis (MS), and with normal MR-images compared to healthy volunteers. This 'MRI-negative' group consisted of fourteen patients which were compared with fourteen healthy controls. Absolutely quantified proton MR-spectra were acquired from four different voxels in NAWM.

Significant differences in absolute metabolite concentrations were observed between the two groups. The MS-patients had lower total N-acetyl compounds (tNA) (p=0.002) compared to the healthy controls and lower concentration of choline-containing compounds (Cho) compared to the healthy controls (p<0.001). EDSS showed a slightly positive correlation to myolns concentrations (0.14mM/EDSS,r2 = 0.06) and a slightly negative correlation to tNA concentrations (-0.41 mM/EDSS,r2 = 0.22). The finding of lower Cho concentrations has not been reported previously and was unexpected.

In Paper III a new rapid imaging method was presented for determination of proton density, B1, T2* relaxation and T1 relaxation. The method was based on a modified Look-Locker pulse sequence with two main differences. (1) The exchange of the inversion pulse in the Lock-Looker sequence to a saturation pulse in order to enable detection of the B1 field, and (2) the introduction of a multi-echo read-out to enable the detection of T2*. The signal intensity was then scaled to proton density using the estimated B1, T1, and T2* value.

The method was validated in vitro, using phantoms filled with solution of different T1 and T2* water relaxation values, and by comparing the results of the measurements to reference metcyods. In vivo the method was compared with literature values.

The validation showed that the method was highly accurate, both in vitro and in vivo, and that this method enabled quantitative imaging of MR-parameters within a clinically feasible examination time. Potential applications of the method are, among a great range of possibilities, to rapidly provide all the necessary quantification parameters in MR-spectroscopy, and to simultaneously provide fast quantitative diagnostic imaging.

sted, utgiver, år, opplag, sider
Linköping: Radiofysik, Linköpings universitet, 2008. s. 72
Serie
Linköping Studies in Health Sciences. Thesis, ISSN 1100-6013 ; 86
Emneord
Mapping--methods, Choline--analysis, Liver diseases--diagnosis, Magnetic resonance imaging--methods, Magnetic resonance spectroscopy--methods, Multiple sclerosis--diagnosis, Multiple sclerosis--metabolism, Nerve fibers, myelinated--metabolism
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-44480 (URN)76794 (Lokal ID)978-91-7393-858-7 (ISBN)76794 (Arkivnummer)76794 (OAI)
Presentation
(engelsk)
Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2019-06-14bibliografisk kontrollert

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