• 제목/요약/키워드: MR spectroscopy

검색결과 143건 처리시간 0.022초

두경부 MRS검사의 SVS와 3D CSI 데이터의 비교 분석및 임상응용을 위한 연구 (A Comparison of MRS Data for SVS and 3D CSI in Human Brain Study)

  • 윤성익;최보영
    • 한국의학물리학회:학술대회논문집
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    • 한국의학물리학회 2005년도 제30회 춘계학술대회
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    • pp.93-95
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    • 2005
  • 자기공명분광법은 극소의 체적내애서 핵자기공명에 의하여 생화학적 성질들을 고유한 주파수에 따라서 대사물질의 신호를 얻는다. 핵자기공명의 신호는 경사자장 혹은 주파수의 크기를 조절하여 체내의 조직성분을 충분히 포함하여 통과시킨다. 획득되어진 원래 데이터는 TE, TR 등의 물리적 상수값의 변화에 의해서 영향을 받는다. 최근의 펄스 시퀀스는 고해상도 3D CSI 및 SVS가 국소적인 체적내의 대사물질의 변화량을 정성적으로 감지하므로 임상데이터로 활용하기 위한 연구가 더욱 절실하다.

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Metabolic Abnormalities in Idiopathic Parkinson's Diseases with Unilateral Symptoms

  • Choe, Bo-Young;Kim, Moon-Chan;Kim, Bum-Soo;Lee, Jae-Moon
    • 한국자기공명학회논문지
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    • 제8권1호
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    • pp.28-36
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    • 2004
  • Authors investigated whether there is a lateral effect of $^1$H MRS observable metabolite ratios between the symptomatic and the nonsymptomatic side in the early stage of Parkinson's disease with unilateral symptom. Localized in vivo $^1$H MR spectroscopy (MRS) was used to measure the metabolite levels in the symptomatic and the nonsymptomatic sides of the lentiform nucleus in Parkinson"s disease with unilateral symptom (N=25). The metabolite ratios of NAA/Cr and Cho/Cr in the symptomatic side were compared with those in the nonsymptomatic side. Significant metabolic lateral effect of NAA/(Cho+Cr) ratio was established between the symptomatic and the nonsymptomatic side of lentiform nucleus in Parkinson's disease with unilateral symptom (p<0.05). The ratio of NAA/(Cho+Cr) homolateral to the sympatomatic side of the patient is also lower than that of the control (P<0.05). On the basis of NAA/Cr ratios of lentiform nucleus between the symptomatic and the nonsymptomatic side, the present $^1$H MRS study shows a significant neuronal laterality in Parkinson's disease with unilateral symptom. In vivo $^1$H MRS may provide a diagnostic marker for neuronal dysfunction in Parkinson's disease with unilateral symptom.

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폐암의 생체 수소자기공명분광법의 실행가능성 (Feasibility of $In$ $vivo$ Proton Magnetic Resonance Spectroscopy for Lung Cancer)

  • 윤순호;박창민;이창현;송인찬;이현주;구진모
    • Investigative Magnetic Resonance Imaging
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    • 제16권1호
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    • pp.40-46
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    • 2012
  • 목적: 폐암의 생체 수소자기공명분광법의 실행가능성을 탐색하고자 하였다. 대상과 방법: 이 전향적 연구는 해당병원의 임상시험심사위원회로 승인을 받았고 모든 환자로부터 사전동의를 받았다. 병리적으로 폐암으로 확인된 (평균 직경, 56.8 mm; 범위, 44-77 mm) 10명의 환자들에서 (남자 7명, 여자 3명; 평균나이, 64.4세) 단일 복셀 수소자기공명분광기법으로 호흡 유발 PRESS (point-resolved spectroscopic sequence)를 사용하여 1.5 T 수소자기공명 분광법을 시행하였다. 스펙트럼 습득의 기술적 성공률을 평가하고 실패한 증례들의 이유를 고찰하였다. 결과: 10개의 폐암 중 8개 폐암에서 분석 가능한 수소자기공명 분광 스펙트럼을 획득했다 (기술적 성공률, 80%). 두 개의 수소자기공명 분광 데이터는 심각한 기준치 왜곡으로 분석할 수 없었다. 대표적인 대사물질로 choline과 lipid들이 관찰되었다. 결론: 비록 제한적 수의 환자에서의 결과이지만 폐암에서 얻어진 생체 수소 자기공명 분광 스펙트럼이 분석가능하고 높은 성공률로 획득하였기 때문에 폐암 환자에서 호흡 유발 PRESS 방법을 사용한 생체 수소자기공명분광법이 실행가능하다고 판단된다.

유체타진손상기법에 의한 ICR 쥐의 뇌손상: 자기공명분광법 (Traumatic Contusion of ICR Mouse Brain by FPI : $^{1}\textrm{H}$ MR Spectroscopic Study)

  • Park, Chi-Bong;Kim, Hwi-Yool;Jeun, Sin-Soo;Han, Young-Min;Han, Duk-Young;Kang, Young-Woon;Choe, Bo-Young
    • 한국의학물리학회지:의학물리
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    • 제14권4호
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    • pp.259-267
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    • 2003
  • 실험적 뇌손상 전후에 쥐의 뇌대사물질 변화를 4.7 T 자기공명분광법을 이용하여 조사하여 보았다. 자기공명 스펙트럼는 비교대상 그룹으로서 정상 쥐 우측 두전엽 피질에서 획득되었다. 유체타진손상기법(Fluid Percussion Injury)을 사용하여 뇌손상을 유발시킨후 3일 후 스펙트럼이 얻어졌다. 뇌손상 쥐의 뇌대사불질들의 변화는 정상쥐의 뇌대사물질들과 비교되었다. Neuronal marker로써 NAA/Cr 비율은 대조군에서 1.13$\pm$0.12이었고 뇌좌상부위에서 0.90$\pm$0.11로 손상전과 비교하여 대조군에 비해 유의성있는 감소소견을 나타내었으며 이는 neuronal loss를 의미하는 것으로 추정된다(P=0.001). Cho/Cr 비율은 대조군에서 0.76$\pm$0.15이었고 뇌좌상부위에서 0.91$\pm$0.17로 손상전과 비교하여 대조군에 비해 유의성있게 증가하는 경향을 나타내었으며 이는 생체막의 파괴나 염증반응과 관련된 것으로 추정된다(P=0.02). 하지만 Glx/Cr 비율은 손상전후에 유의성있는 변화를 나타내지 않았다. Lac/Cr 비율은 대조군에 비해 증가하는 경향을 나타내었고 이는 외상후 에너지 대사의 변위양상으로 고려되어진다. 이러한 소견들은 자기 공명분광법이 유체타진손상기법을 이용한 외상성 뇌좌상에서 신경병리학적 변화과정에 대한 이해를 증진시키고 나아가 외상에 의한 뇌좌상의 임상적인 평가를 위해 매우 유용한 modality임을 시사하는 것이라고 사료된다. 그러나 본 연구에서 몇몇의 케이스에서 voxel을 선정하면서 두개골의 일부가 포함되거나 혹은 죄상과 동반된 출혈로 인해 유용한 데이터를 획득하는데 어려움을 주기도 하였다. 앞으로 보다 더 세밀한 분석과 연구를 위해 유체타진 손상의 다양한 정도에서 대사물질들의 변화양상을 평가할 필요가 있을 것으로 사료된다. .

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MR Technology to 4T

  • Vaughan, Thomas
    • 대한자기공명의과학회:학술대회논문집
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    • 대한자기공명의과학회 2003년도 제8차 학술대회 초록집
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    • pp.103-105
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    • 2003
  • After fifteen years of development, Magnetic Resonance (MR) technology for human imaging and spectroscopy is reaching a refined state with FDA approved 3T clinical products from Siemens, GE, and Philips. Broker has cleared CE approval with a 4T system. Varian supports a 4T system platform as well. Shielded magnets are standard at 3T from GE, Oxford, Magnex, and IGC. A shielded 4T whole body magnet is available from Oxford. Stronger switched gradients and dynamic shim coils, desired at any field, areespecially useful at higher static magnetic fields B0. In addition to the higher currents required for higher resolution slice or volume selection afforded by higher SNR, whole body gradient coils will be driven at increasing slew rates to meet the needs of new cardiac applications and other requirements. For example 3T and 4T systems are now being equipped with 2kV, 500A gradient coils and amplifiers capable of generating 4G/cm in 200msec, over a 67+/-cm bore diameter. High field EPI applications require oscillation rates at 1 kHz and higher. To achieve a benchmark 0.2 ppm shim over a 30cm sphere in a high field magnet, at least four stages of shimming need to be considered. 1) A good high field magnet will be built to a homogeneity spec. falling in the range of 100 to 150 ppm over this 30cm spherical "sweet spot" 2) Most modern high field magnets will also have superconducting shim coils capable of finding 1.5 ppm by their adjustment during system installation. 3) Passive ferro-magnetic shimming combined with 4) active, high order room temperature shim coils (as many as five orders are now being recommended) will accomplish 0.2 ppm over the 30cm sphere, and 0.1 ppm over a human brain in even the highest field magnets for human studies. Safety concerns for strong, fast gradients at any B0 field include acoustic noise and peripheral nerve stimulation. One or more of the mechanical decoupling methods may lead to quieter gradients. Patient positioning relative to asymmetric or short gradient coils may limit peripheral nerve stimulation at higher slew rates. Gradient designs combining a short coil for local speed and strength with a longer coil for coverage are being developed for 3T systems. Local gradients give another approach to maximizing performance over a limited region while keeping within the physiologically imposed dB0/dt performance limits.

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Simultaneous Estimation of the Fat Fraction and R2* Via T2*-Corrected 6-Echo Dixon Volumetric Interpolated Breath-hold Examination Imaging for Osteopenia and Osteoporosis Detection: Correlations with Sex, Age, and Menopause

  • Donghyun Kim;Sung Kwan Kim;Sun Joo Lee;Hye Jung Choo;Jung Won Park;Kun Yung Kim
    • Korean Journal of Radiology
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    • 제20권6호
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    • pp.916-930
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    • 2019
  • Objective: To investigate the relationships of T2*-corrected 6-echo Dixon volumetric interpolated breath-hold examination (VIBE) imaging-based fat fraction (FF) and R2* values with bone mineral density (BMD); determine their associations with sex, age, and menopause; and evaluate the diagnostic performance of the FF and R2* for predicting osteopenia and osteoporosis. Materials and Methods: This study included 153 subjects who had undergone magnetic resonance (MR) imaging, including MR spectroscopy (MRS) and T2*-corrected 6-echo Dixon VIBE imaging. The FF and R2* were measured at the L4 vertebra. The male and female groups were divided into two subgroups according to age or menopause. Lin's concordance and Pearson's correlation coefficients, Bland-Altman 95% limits of agreement, and the area under the curve (AUC) were calculated. Results: The correlation between the spectroscopic and 6-echo Dixon VIBE imaging-based FF values was statistically significant for both readers (pc = 0.940 [reader 1], 0.908 [reader 2]; both p < 0.001). A small measurement bias was observed for the MRS-based FF for both readers (mean difference = -0.3% [reader 1], 0.1% [reader 2]). We found a moderate negative correlation between BMD and the FF (r = -0.411 [reader 1], -0.436 [reader 2]; both p <0.001) with younger men and premenopausal women showing higher correlations. R2* and BMD were more significantly correlated in women than in men, and the highest correlation was observed in postmenopausal women (r = 0.626 [reader 1], 0.644 [reader 2]; both p < 0.001). For predicting osteopenia and osteoporosis, the FF had a higher AUC in men and R2* had a higher AUC in women. The AUC for predicting osteoporosis was highest with a combination of the FF and R2* in postmenopausal women (AUC = 0.872 [reader 1], 0.867 [reader 2]; both p < 0.001). Conclusion: The FF and R2* measured using T2*-corrected 6-echo Dixon VIBE imaging can serve as predictors of osteopenia and osteoporosis. R2* might be useful for predicting osteoporosis, especially in postmenopausal women.

ADVANTAGES OF USING ARTIFICIAL NEURAL NETWORKS CALIBRATION TECHNIQUES TO NEAR-INFRARED AGRICULTURAL DATA

  • Buchmann, Nils-Bo;Ian A.Cowe
    • 한국근적외분광분석학회:학술대회논문집
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    • 한국근적외분광분석학회 2001년도 NIR-2001
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    • pp.1032-1032
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    • 2001
  • Artificial Neural Network (ANN) calibration techniques have been used commercially for agricultural applications since the mid-nineties. Global models, based on transmission data from 850 to 1050 nm, are used routinely to measure protein and moisture in wheat and barley and also moisture in triticale, rye, and oats. These models are currently used commercially in approx. 15 countries throughout the world. Results concerning earlier European ANN models are being published elsewhere. Some of the findings from that study will be discussed here. ANN models have also been developed for coarsely ground samples of compound feed and feed ingredients, again measured in transmission mode from 850 to 1050 nm. The performance of models for pig- and poultry feed will be discussed briefly. These models were developed from a very large data set (more than 20,000 records), and cover a very broad range of finished products. The prediction curves are linear over the entire range for protein, fat moisture, fibre, and starch (measured only on poultry feed), and accuracy is in line with the performance of smaller models based on Partial Least Squares (PLS). A simple bias adjustment is sufficient for calibration transfer across instruments. Recently, we have investigated the possible use of ANN for a different type of NIR spectrometer, based on reflectance data from 1100 to 2500 nm. In one study, based on data for protein, fat, and moisture measured on unground compound feed samples, dedicated ANN models for specific product classes (cattle feed, pig feed, broiler feed, and layers feed) gave moderately better Standard Errors of Prediction (SEP) compared to modified PLS (MPLS). However, if the four product classes were combined into one general calibration model, the performance of the ANN model deteriorated only slightly compared to the class-specific models, while the SEP values for the MPLS predictions doubled. Brix value in molasses is a measure of sugar content. Even with a huge dataset, PLS models were not sufficiently accurate for commercial use. In contrast an ANN model based on the same data improved the accuracy considerably and straightened out non-linearity in the prediction plot. The work of Mr. David Funk (GIPSA, U. S. Department of Agriculture) who has studied the influence of various types of spectral distortions on ANN- and PLS models, thereby providing comparative information on the robustness of these models towards instrument differences, will be discussed. This study was based on data from different classes of North American wheat measured in transmission from 850 to 1050 nm. The distortions studied included the effect of absorbance offset pathlength variation, presence of stray light bandwidth, and wavelength stretch and offset (either individually or combined). It was shown that a global ANN model was much less sensitive to most perturbations than class-specific GIPSA PLS calibrations. It is concluded that ANN models based on large data sets offer substantial advantages over PLS models with respect to accuracy, range of materials that can be handled by a single calibration, stability, transferability, and sensitivity to perturbations.

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경도 두부외상 환자에서 뇌좌상주위 부종영역에서의 자기공명분광법을 이용한 대사변화 (Metabolic Changes in Pericontusional Edematous Areas in Mild Head Injury Evaluated by Proton MRS)

  • 홍상수;손병철;최병길;김의녕;김범수;박춘근;최보영;김문찬;강준기
    • Journal of Korean Neurosurgical Society
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    • 제29권9호
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    • pp.1233-1237
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    • 2000
  • Objectives : In order to evaluate the metabolic changes associated with pericontusional edematous area in mild head injury, proton magnetic resonance spectroscopy(1H-MRS) was performed in mild head injury patients (initial GCS score 13-15) with focal brain contusion. Methods : Seven head injury patients with initial GCS 13-15(3 males and 4 females : age range 15-65 years, mean age 33 years) have underwent 1H-MRS evaluations. The patients were examined within 7 days after injury(n=7) and 2 months after injury(n=5). The region of interest(ROI) was selected in the edematous area adjacent to traumatic brain contusion upon T2-weighted MR images and a corresponding region of the contralateral hemisphere (ROC, region of contralateral corresponding hemisphere) was examined as well. The metabolic ratios of NAA/Cr and lactate/Cr were compared between ROIs, ROCs and control values. Results : In initial NAA/Cr ratios, the values of ROIs were significantly lower than those of the controls(p=0.009), but there was no difference either between ROIs and ROCs(p=0.410) or between ROCs of patients and the control (p=0.199). In lactate/Cr ratios, the ROIs in all seven patients and the ROCs in two showed increased lactate signals. The lactate/Cr ratios of the ROIs were significantly elevated as compared to those of the ROCs(p=0.02) and the control(p=0.015). In two months follow-up, lactate signals were absent or significantly reduced(p=0.015). In no patients, clinical or radiological deterioration has been observed. Conclusion : Our 1H-MRS results demonstrate that there are significant ischemic changes in pericontusional edematous areas as indicated by elevated lactate signals in the patients with mild head injury. But there were no consistent neural loss or dysfunction in these area. There findings suggest that pericontusional edematous areas can be vulnerable to secondary brain insults even in the patients with mild head injury.

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양성자 화학적 이동영상기법(1H-CSI)을 이용한 정위적 뇌생검 (Proton Magnetic Resonance Chemical Shift Imaging(1H-CSI)-directed Stereotactic Brain Biopsy)

  • 장경술;손병철;김문찬;최병길;김의녕;김범수;최보영;백현만;홍용길;강준기
    • Journal of Korean Neurosurgical Society
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    • 제29권12호
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    • pp.1606-1611
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    • 2000
  • Objective : To obtain more reliable sample in stereotactic biopsy, authors adopted proton chemical shift imaging ($^1H$-CSI)-directed biopsy. Until now, proton single voxel spectroscopy($^1H$-SVS) technique has been reported as a technique using metabolic information in stereotactic biopsy. The authors performed $^1H$-CSI with a stereotactic headframe in place and evaluated the pathologic results obtained from local metabolic information through $^1H$-CSI. Methods : $^1H$ CSI-directed stereotactic biopsy was performed in four patients. $^1H$-CSI and conventional Gd-enhancement stereotactic MRI was done simultaneously after application of the stereotatic frame. After reconstruction of metabolic maps of NAA/Cr, Cho/Cr, and Lactate/Cr ratios, the focal areas of increased Cho/Cr ratios and decreased NAA/Cr ratios were selected for target sites in the MR images Results : There was no difficulty in performing $^1H$-CSI with the stereotactic headframe in place. In pathologic examinations, the samples taken in area of increased Cho/Cr ratios and decreased NAA/Cr ratios showed the features of increased cellularity, mitoses and cellular atypism, thus facilitated the diagnosis. The pathologic samples taken from the area of increased Lactate/Cr ratios showed prominent feature of necrosis. Conclusion : $^1H$-CSI was feasible with stereotactic head frame in place. The final pathologic results obtained in our samples were concordant with the local metabolic informations from $^1H$-CSI. Authors believe that $^1H$ CSI-directed stereotactic biopsy may provide us advantages in obtaining more reliable tissue specimen in stereotactic biopsy.

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Metabolic Changes in Patients with Parkinson's Disease after Stereotactic Neurosurgery by Follow-up 1H MR Spectroscopy

  • Choe, Bo-Young;Baik, Hyun-Man;Chun, Shin-Soo;Son, Byung-Chul;Kim, Moon-Chan;Kim, Bum-Soo;Lee, Hyoung-Koo;Suh, Tae-Suk
    • 한국자기공명학회논문지
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    • 제5권2호
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    • pp.99-109
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    • 2001
  • Authors investigated neuronal changes of local cellular metabolism in the cerebral lesions of Parkinsonian symptomatic side between before and after stereotactic neurosurgery by follow-up 1H magnetic resonance spectroscopy (MRS). Patients with Parkinson's disease (PD) (n = 15) and age-matched normal controls (n = 15) underwen MRS examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2${\times}$2${\times}$2 ㎤ (8ml) volume of interest in the regions of substantia nigra, thalamus, and lentiform nucleus. Spectral parameters were 20 ms TE, 2000 ms TR, 128 averages,2500 Hz spectral width, and 2048 data points. Raw data were processed by the SAGE data analysis package (GE Medical Systems). Peak areas of N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum (Glx) of glutamate and GABA were calculated by means of fitting the spectrum to a summation of Lorentzian curves using Marquardt algorithm. After blindly processed, we evaluated neuronal alterations of observable metabolite ratios between before and after stereotactic neurosurgery using Pearson product-moment analysis (SPSS, Ver. 6.0). A significant reduction of NAA/Cho ratio was observed in the cerebral lesion in substantia nigra of PD patient related to the symptomatic side after neurosurgery (P : 0.03). In thalamus, NAA/Cho ratio was also significantly decreased in the cerebral lesion including the electrode-surgical region (P : 0.03). A significant reduction of NAA/Cho ratio in lentiform nucleus was not oberved, but tended toward significant reduction after neurosurgery (P = 0.08). In particular, remarkable lactate signal was noted from the surgical thalamic lesions of 6 among 8 patients and internal segments of globus pallidus of 6 among 7 patients, respectively. Significant metabolic alterations of NAA/Cho ratio might reflect functional changes of neuropathological processes in the lesion of substantia nigra, thalamus, and lentiform nucleus, and could be a valuable finding fur evaluation of Parkinson's disease after neurosurgery. Increase of lactate signals, being remarkable in surgical lesions, could be consistent with a common consequence of neurosurgical necrosis. Thus, IH MRS could be a useful modality to evaluate the diagnostic and prognostic implications fur Parkinsons disease after functional neurosurgery.

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