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Administration of contrast media before proton magnetic resonance spectroscopy (1H MRS) may allow more accurate placement of the volume of interest in breast tumors, but some studies have suggested their use decreases the choline peak. We studied the impact of contrast use to determine which method would reduce the choline peak the least. Phantoms containing 1, 5, and 10 mM concentrations of choline were prepared in phosphate-buffered saline and mixed with contrast media in concentrations of 0, 0.2, 0.4, and 0.6 mM. We used 2 different media: one being a negatively-charged diethylenetriaminepentaacetic acid gadolinium (Gd-DTPA), and the other a neutral gadoteridol (Gd-HP-DO3A). We studied all phantoms by single voxel 1H MRS with a repetition time (TR) of 2,000 msec and an echo time (TE) of 136 or 270 msec. Gd-DTPA tended to induce an increase in the peak integral and amplitude at lower concentrations and a decrease at a higher concentration, whereas Gd-HP-DO3A tended to induce an increase in the peak integral and amplitude at lower concentrations with no definite decrease at higher concentrations. Neither contrast medium induced a definite change in peak width. The reduction of the choline peak integral and amplitude at TE of 270 msec was greater than at TE of 136 msec. Therefore, we recommend the use of the neutral contrast agent and short TE in 1H MRS studies of breast tumors to avoid underestimation of the level of choline peaks.

【目的】本研究は, 小児期から若年成人期にかけての脳成熟に伴う, 大脳皮質および小脳皮質のグルタミン酸 (Glu) の変化を, 3.0T proton magnetic resonance spectroscopy (^1H-MRS) を用いて明らかにすることを目的とした. 【方法】小児群 (4-13歳, 11例), 若年成人群 (18-33歳, 11例) から成る健常人22例を対象とした. 本研究は新潟大学倫理委員会の承認のもと, 書面によるインフォームドコンセントを得て施行した. 3.OT MR装置を用いて, 前頭葉皮質, 後頭葉皮質および小脳虫部におけるシングルボクセル^1H-MRSを撮像した. スペクトルの解析にはLCModelを用い, Gluのクレアチン化合物 (Cr) に対する比を算出した. 【結果】前頭葉皮質及び後頭葉皮質におけるGlu/Crは年齢と負の相関を示した. 小脳虫部におけるGlu/Crは年齢との相関を示さなかった. 【結論】本研究により, 小児期から若年成人期にかけて, 大脳皮質のGlu/Crが年齢依存性に低下することが明らかにされた. このGlu/Crの低下は, 大脳の神経回路綱が成熟する過程で生じる, 皮質シナプス密度の低下と代謝コンパートメントの変化を反映していると考えられた. 大脳皮質のGlu/Crは, 3.0T^1H-MRSを用いることにより生体で非侵襲的かつ簡便に評価可能であり, 大脳皮質における神経回路網の成熟を反映する指標として有用である可能性がある.

金沢大学医薬保健研究域保健学系, In Japan, breast MRI is widespread as a diagnostic modality following mammography and ultrasound. The main purpose of performing breast MRI is to determine the extent of carcinoma, especially in ductal carcinoma in situ (DCIS) .For the diagnosis of DCIS, a morphological evaluation is more useful than the time-intensity curve in contrast-enhanced MRI. Recently, neoadjuvant chemotherapy for breast cancer has increased and MRI is considered to be the best method to evaluate its effect. MR spectroscopy and MRI-guided biopsy are also promising methods, however, there are many problems related to their clinical use.

Proton Magnetic Resonance Spectroscopy (1H-MRS) can be used to detect cerebral metabolites including N-acetylaspartate (NAA)，creatine (Cr) and choline (Ch). Hence，clinical applications of this method for neuropediatric diseases can be expected. However，regarding neuronal migration disorders，there have been only a few reported studies. We therefore examined the lH-MRS in six patients with migration disorders，ages ranged from 8months to 28years 10months with a mean of 10years 10months. Investigation was performed using Magnetom H15 (Siemens) with a repetition time of 1500 msec and an echo time of 270msec. The ratio of NAA/Cr，Ch/Cr were examined. The volume of interest with the size of 2 × 2 × 2 ～ 3 × 3 × 5cm3 was chosen in the area including lesions，and a contralateral area without lesions was also investigated. Results were as follows. 1) The ratio of NAA/Cr was low in the area with lesions in all 6cases; 1.41，1.95，2.27 and 1.71 in cases with heterotopic gray matter，0.99 in one case with polymicrogyria，an d 1.30 in one case with hemimegalencephaly，contrasted with a contralataral area without lesions: 1.89， 2.89，2.87，2.55，3.26，2.03，respectively. 2) The ratio of Ch/Cr showed no consistent difference between the area including lesions and contralataral area without lesions. Our findings of a decreased NAA/Cr ratio can be inferred to reflect the decreased numbers of neuronal cell population，or reduced metabolism in the lesions.

We tested the reliability of quantifying brain metabolite concentrations by MR spectroscopy. We employed a PRESS sequence and used a cyclohexane sample as an external standard. The signal intensity ratios of water and cyclohexane were measured by changing the geometrical arrangement of the cyclohexane sample and water phantom with various loading factors of the coil. Choline (Cho) concentrations were calculated from the signal intensity ratios of Cho and water and compared with actual Cho concentrations (1.0 to 2.6 mmol/L). The brain metabolites Cho, creatine/phosphocreatine (Cr/PCr) and N-acetylaspartate (NAA) were evaluated in five normal volunteers and six patients with metastatic brain cancer before (0 Gy), after 20 Gy and after 40 Gy of whole brain radiotherapy. Variation in the ratio of spectrum intensity between water and cyclohexane was less than 1.5% for various geometrical arrangements and loading factors. The error in quantification of Cho concentrations in the phantom study was 0.05 +/- 0.10 mmol/L. The concentrations measured in the volunteers were: Cho 1.6 +/- 0.4 mmol/L, Cr/PCr 6.4 +/- 1.1 mmol/L and NAA 8.2 +/- 0.1 mmol/L. There was no significant difference (p > 0.05) in these concentrations between the control group and the patients before, during, or after radiotherapy.