• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.35-40
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• 2002

Purpose : To evaluate the NMR relaxation properties and imaging characteristics of tissue-specificity for a newly developed macromolecular MR agent. Materials and methods : Phthalocyanine (PC) was chelated with paramagnetic ion, Mn.2.01g (5.2 mmol) of Phthalocyanine was mixed with 0.37g (1.4 mmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography (CHC13/CH3OH 98/2 v/v, Rf, 0.76) to obtain 1.04g (46%) of MnPC (molecular weight= 2000d). The $T1}T2$ relaxivity of MnPC was measured in 1.5T(64 MHz) MR using 0.1 mM MnPC. The MR image characteristics of MnPC was evaluated using spin-echo (TR/TE=500/14 msec) and gradient-echo (FLASH) (TR/TE=80/4 msec, flip angle=60) techniques in 1.57 MR scanner. The images of rabbit liver were obtained every 10 minutes up to 4 hours. To study the effect of concentration on image, 20 mM, 50 mM, 100 mM of MnPC were tested. Results : The relaxivities of MnPC at 1.5T(64MHz) were Rl=7.28 $mM^{-1}S^{-1},{\;}R2=55.56mM^{-1}S^{-1}$. Compared to the values of Gd-DTPA (Rl[=4.8 $mM^{-1}S^{-1})$], R2[=5.2 $mM^{-1}S^{-1}])$]), both T1/T2 relaxivities of MnPC were higher than those of Gd-DTPA. For both of SE and FLASH techniques, the contrast enhancement reached maximum at 10 minutes after bolus injection and the enhancement continued for more than 2 hours. When compared with small molecular weight liver agents such as Gd-EOB-DTPA, Gd-BOPTA and MnDPDP, MnPC was characterized by more prolonged enhancement time. The time course of MR images also revealed biliary excretion of MnPC. Conclusion : We developed a new macromolecular MR agent, MnPC. The relaxivities of MnPC were higher than those of small molecular weight Gd-chelate. Hepatic uptake and biliary excretion of MnPC suggests that this agent is a new liver-specific MR agent.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.9-16
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• 2004

Purpose : The purpose of this study was to assess supplementary motor area (SMA) activation during motor, sensory, word generation, listening comprehension, and working memory tasks using functional magnetic resonance imaging (fMRI). Materials and Methods : Sixteen healthy right-handed subjects (9M, 7F) were imaged on a Siemens 1.5T scanner. Whole brain functional maps were acquired using BOLD EPI sequences in the axial plane. Each paradigm consisted of five epochs of activation vs. the control condition. The activation tasks consisted of left finger complex movement, hot sensory stimulation of the left hand, word generation, listening comprehension, and working memory. The reference function was a boxcar waveform. Activation maps were thresholded at an uncorrected p=0.0001. The thresholded activation maps were placed into MNI space and the anatomic localization of activation within the SMA was compared across tasks. Results : SMA activation was observed in 16 volunteers for the motor task, 11 for the sensory task, 15 for the word generation task, 5 for the listening comprehension task, and 15 for the working memory task. The rostral aspects of the SMA showed activity during the word generation and working memory tasks, and the caudal aspects of the SMA showed activity during the motor and sensory tasks. Right (contralateral) SMA activation was observed during the motor and sensory tasks, and left SMA activation during the word generation and memory tasks. Conclusion : Our results suggest that SMA is involved in a variety of functional tasks including motor, sensory, word generation, and working memory. The results obtained also support the notion that functionally specific subregions exist within the region classically defined as the SMA.