Quantitative T1ρ and adiabatic Carr–Purcell T2 magnetic resonance imaging of human occipital lobe at 4 T

The feasibility of performing quantitative T1ρ MRI in human brain at 4 T is shown. T1ρ values obtained from five volunteers were compared with T2 and adiabatic Carr–Purcell (CP) T2 values. Measured relaxation time constants increased in order from T2, CP‐T2, T1ρ both in white and gray matter, demonstrating differential sensitivities of these methods to dipolar interactions and/or proton exchange and diffusion in local microscopic field gradients, which are so‐called dynamic averaging (DA) processes. In occipital lobe, all relaxation time constants were found to be higher in white matter than in gray matter, demonstrating contrast denoted as an “inverse transverse relaxation contrast.” This contrast persisted despite changing the delay between refocusing pulses or changing the magnitude of the spin‐lock field strength, which suggests that it does not originate from DA, as might be induced by the presence of Fe, but rather is related to dipolar interactions in the brain tissue. Magn Reson Med 54:14–19, 2005. © 2005 Wiley‐Liss, Inc.

[1]  Arijitt Borthakur,et al.  In vivo measurement of T1ρ dispersion in the human brain at 1.5 tesla , 2004 .

[2]  Raimo Sepponen,et al.  A Method for Tlp Imaging , 1985 .

[3]  Ray Freeman,et al.  Compensation for Pulse Imperfections in NMR Spin-Echo Experiments , 1981 .

[4]  Peter Andersen,et al.  In vivo 1H2O T  †2 measurement in the human occipital lobe at 4T and 7T by Carr‐Purcell MRI: Detection of microscopic susceptibility contrast , 2002, Magnetic resonance in medicine.

[5]  R. Gruetter,et al.  In vivo 1H NMR spectroscopy of rat brain at 1 ms echo time , 1999, Magnetic resonance in medicine.

[6]  M. S. Silver,et al.  Highly selective {π}/{2} and π pulse generation , 1984 .

[7]  R. Reddy,et al.  Quantitative T1rho magnetic resonance imaging of RIF-1 tumors in vivo: detection of early response to cyclophosphamide therapy. , 2001, Cancer research.

[8]  R. Brooks,et al.  T1 and T2 in the brain of healthy subjects, patients with Parkinson disease, and patients with multiple system atrophy: relation to iron content. , 1999, Radiology.

[9]  R. Kauppinen,et al.  Inverse T2 contrast at 1.5 Tesla between gray matter and white matter in the occipital lobe of normal adult human brain , 2001 .

[10]  A Brun,et al.  Regional Differences in the Proton Magnetic Resonance Relaxation Times T1 and T2 within the Normal Human Brain , 1986, Acta radiologica: diagnosis.

[11]  J. B. Kneeland,et al.  In vivo proton MR three-dimensional T1rho mapping of human articular cartilage: initial experience. , 2003, Radiology.

[12]  Masashi Yamaguchi,et al.  Side Chain Dynamics in Poly(γ-benzyl L-glutamate) as Studied by High-Resolution Solid State 13C Nuclear Magnetic Relaxation in Rotating Frame , 1993 .

[13]  Asla Pitkänen,et al.  Early Detection of Irreversible Cerebral Ischemia in the Rat Using Dispersion of the Magnetic Resonance Imaging Relaxation Time, T1ρ , 2000, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[14]  M. Garwood,et al.  Asymmetric adiabatic pulses for NH selection. , 1999, Journal of magnetic resonance.

[15]  Michael Garwood,et al.  Transverse relaxation in the rotating frame induced by chemical exchange. , 2004, Journal of magnetic resonance.

[16]  R M Henkelman,et al.  Spin locking for magnetic resonance imaging with application to human breast , 1989, Magnetic resonance in medicine.

[17]  Olli Gröhn,et al.  Exchange‐influenced T2ρ contrast in human brain images measured with adiabatic radio frequency pulses , 2005, Magnetic resonance in medicine.

[18]  F. Ye,et al.  Estimation of the iron concentration in excised gray matter by means of proton relaxation measurements , 1996, Magnetic resonance in medicine.

[19]  R. Kauppinen,et al.  Novel magnetic resonance imaging contrasts for monitoring response to gene therapy in rat glioma. , 2003, Cancer Research.