Bio-energetic impairment in human calf muscle in thyroid disorders: a P MRS study

Mitochondrial metabolism particularly oxidative phosphorylation is greatly influenced by thyroid hormones. Earlier studies have described neuromuscular symptoms as well as impaired muscle metabolism in hypothyroid and hyperthyroid patients. In this study, we intend to look in to the muscle bioenergetics including phosphocreatine recovery kinetics based oxidative metabolism in thyroid dysfunction using in vivo ³¹P nuclear magnetic resonance spectroscopy (MRS). ³¹P MRS was carried out at resting state on 32 hypothyroid, 10 hyperthyroid patients and 25 control subjects. Nine out of 32 hypothyroid patients and 17 out of 25 control subjects under went exercise protocol for oxidative metabolism study and performed plantar flexion exercise while lying supine in 1.5 T magnetic resonance scanner using custom built exercise device. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), phosphodiesters (PDE) and adenosine triphosphate (ATP) of the calf muscle were acquired during rest, exercise and recovery phase. PCr recovery rate constant (k_PCr) and oxidative capacity were calculated by monoexponential fit of PCr versus time (t) at the beginning of recovery. During resting condition in hypothyroid patients, PCr/Pi ratio was reduced whereas PDE/ATP and Pi/ATP were increased. However, in case of hyperthyroidism, an increased PCr/Pi ratio and reduced PDE/ATP and Pi/ATP were observed. The results confirmed differential energy status of the muscle due to increased or decreased levels of thyroid hormone. Our results also demonstrate reduced oxidative metabolism in hypothyroid patients based on PCr recovery kinetics. PCr recovery kinetics study after exercise revealed decreased PCr recovery rate constant (k_PCr) in hypothyroid patients compared to controls that resulted in decrease in oxidative capacity of muscle by 50% in hypothyroids. These findings are consistent with a defect of high energy phosphate mitochondrial metabolism in thyroid dysfunction.     

Relayed magnetization transfer from nuclear Overhauser effect and chemical exchange observed by in vivo ³¹P MRS in rat brain

The ³¹P magnetization transfer effects among nuclear magnetic resonances (NMRs) of phosphocreatine (PCr), γ-adenosine-5'-triphosphate (γ-ATP) and inorganic phosphate (Pi) have been attributed to the chemical exchange reactions among PCr, ATP and Pi catalyzed by creatine kinase (CK) and ATPase enzymes and, therefore, are commonly applied in situ to measure chemical exchange fluxes involving two chemically coupled CK and ATPase reactions (i.e., PCr↔ATP↔Pi) by selectively saturating γ-ATP resonance. Besides the expected reductions in the Pi and PCr NMR signals upon saturating γ-ATP resonance, one particularly interesting phenomenon showing decreases in α-ATP and β-ATP signals was also observed. The underlying mechanism was investigated and identified via saturating NMR of β-ATP in the present study. The unique relayed magnetization transfer effects through spin diffusion were observed in the rat brain using in vivo ³¹P magnetic resonance spectroscopy.     

Effect of creatine monohydrate in improving cellular energetics and muscle strength in ambulatory Duchenne muscular dystrophy patients: a randomized,placebo-controlled P MRS study

Randomized, placebo-controlled single blinded study was carried out to evaluate the effect of oral creatine supplementation on cellular energetics, manual muscle test (MMT) score and functional status in steroid-naive, ambulatory boys suffering with Duchenne muscular dystrophy (DMD; n=33). Eighteen patients received creatine monohydrate (Cr; 5 g/day for 8 weeks), while 15 received placebo (500 mg of vitamin C). Phosphorus metabolite ratios were determined from the right calf muscle of patients using phosphorus magnetic resonance spectroscopy (³¹P MRS) both prior to (baseline) and after supplementation of Cr or placebo. In addition, metabolite ratios were determined in normal calf muscle of age and sex matched controls (n=8). Significant differences in several metabolite ratios were observed between controls and DMD patients indicating a lower energy state in these patients. Analysis using analysis of covariance adjusted for age and stature showed that the mean phosphocreatine (PCr)/inorganic phosphate (Pi) ratio in patients treated with Cr (4.7; 95% CI; 3.9–5.6) was significantly higher (P=.03) compared to the placebo group (3.3; 95% CI; 2.5–4.2). The mean percentage increase in PCr/Pi ratio was also more in patients <7 years of age compared to older patients after Cr supplementation indicating variation in therapeutic effect with the age. In the placebo group, significant reduction in PCr/Pi (P=.0009), PCr/t-ATP (P=.05) and an increase in phosphodiester (PDE)/PCr ratios was observed after supplementation. Further, in the placebo group, patients <7 years showed reduction of PCr/t-ATP and Pi/t-ATP compared to older patients (>7 years), after supplementation. These results imply that the significant difference observed in PCr/Pi ratio between the Cr and the placebo groups after supplementation may be attributed to a decrease of PCr in the placebo group and an increase in PCr in the Cr group. Changes in MMT score between the two groups was significant (P=.04); however, no change in functional scale (P=.19) was observed. Parents reported subjective improvement on Cr supplementation versus worsening in placebo (P=.02). Our results indicated that Cr was well tolerated and oral Cr significantly improved the muscle PCr/Pi ratio and preserved the muscle strength in short term. However, this study provides no evidence that creatine will prove beneficial after long-term treatment, or have any positive effect on patient lifespan.     

Lesion load quantification on fast-FLAIR, rapid acquisition relaxation-enhanced, and gradient spin echo brain MRI scans from multiple sclerosis patients.

Previous studies have addressed the issue of the usefullness of fast fluid-attenuated (fast-FLAIR), rapid acquisition relaxation-enhanced (RARE), and gradient spin echo (GRASE) sequences in small groups of patients with multiple sclerosis (MS). The aim of this study was to assess and compare the lesion volumes and the intra-rater reproducibility of such measurements using fast-FLAIR, dual echo RARE, and dual echo GRASE brain scans from a large sample of MS patients. Using a 1.5 Tesla scanner, fast-FLAIR, dual echo RARE, and dual echo GRASE scans (24 axial, 5-mm thick contiguous interleaved slices) of the brain were obtained from 50 MS patients. Total lesion loads (TLL) were assessed twice using a semi-automated local thresholding segmentation technique by the same rater from the scans obtained with the three techniques. Mean TLL were 20.3 mL for fast-FLAIR, 16.6 mL for RARE, and 17.6 mL for GRASE sequences. Mean TLL detected by the three techniques were significantly heterogeneous (p < 0.001); at post-hoc analysis, the mean lesion volume detected on fast-FLAIR images was significantly higher than that on both RARE and GRASE images (p < 0.001) and the mean TLL on GRASE scans was significantly higher than that on RARE scans (p = 0.001). The mean values of intra-observer coefficient of variation for TLL measurements were similar for the three techniques (2.69% for fast-FLAIR, 2.33% for RARE, and 2.65% for GRASE). Our results confirm that fast-FLAIR sequences detect higher lesion volumes than those detected by other magnetic resonance imaging (MRI) sequences with shorter acquisition times. However, the reproducibility of TLL measurements is comparable among fast-FLAIR, RARE, and GRASE. This suggests that when assessing MS disease burden with MRI, the choice of the pulse sequence to be used should be dictated by the clinical setting.     

Artifact-free black-blood cine cardiac imaging in a single breath-hold

Fast imaging using the STimulated Echo Acquisition Mode (STEAM) sequence can produce cine images of the heart with black-blood contrast. Nevertheless, correction of deformation-related artifacts is required in order to maintain myocardial signal throughout the cardiac cycle. Recent work by our group has eliminated this artifact by combining two STEAM sequences acquired with two different demodulation gradients. Unfortunately, these two STEAM sequences were acquired on two separate breath-holds; thus, scan time doubled. In this work, we present a technique to reduce the total scan time by one half, without sacrificing image quality. The technique is based on interleaving two demodulations within one acquisition in order to obtain quality cine images of the heart in a single breath-hold. The technique was tested on animal models and human subjects, and the impact of interleaved acquisition on image quality was studied using quantitative and qualitative measures.     

Cine-MRI and P-MRS for evaluation of myocardial energy metabolism and function following coronary artery bypass graft

Previous studies investigated the effect of successful coronary artery bypass grafting (CABG) upon left ventricular function. The relationship between myocardial metabolism and heart function after CABG remains unclear. We investigated the relationship between high-energy phosphate (HEP) and cardiac function following CABG using cine magnetic resonance imaging (cine-MRI) and phosphorus-31 magnetic resonance spectroscopy (³¹P-MRS). A retrospective study was approved by the institutional review board. MRI and ³¹P-MRS examinations were reviewed of 37 patients with multivessel disease who underwent CABG. 13 of these patients selected for the retrospective analysis had ≥70% stenosis in the proximal left anterior descending artery (LAD) and left ventricular ejection fraction (LVEF) <40%. LVEF was evaluated using cine-MRI. HEP such as phosphocreatine (PCr) and adenosine triphosphate (β-ATP) was measured using ³¹P-MRS to calculate PCr/β-ATP ratio. Cine-MRI and ³¹P-MRS measurements were performed before and after CABG, respectively. Ten normal healthy volunteers served as controls. ³¹P-MRS in 13 patients showed that post-CABG PCr/β-ATP ratio was significantly higher than that of pre-CABG (pre-CABG vs. post-CABG, 1.43±0.24 vs. 1.71±0.29, P<.05), but both ratios were significantly lower than control group (2.13±0.21, P<.05). With the change of the ratio, the left ventricle function was significantly improved (LVEF: pre-CABG vs. post-CABG: 35.7±12.9 vs. 45.6±17.2, P<.05).     

用3lP NMR研究小鼠脑在缺氧状态下能量代谢的动态变化

用³¹P体内核磁共振方法无损伤地观察了C57小鼠脑在缺氧时与能量代谢有关的含磷化合物Pi,PCr,ATP的动态变化,当气体中氧气含量降到5%时,小鼠大脑的PCr,ATP逐渐减少,Pi不断增加,脑组织内pH值降低至6.83~6.93.当Pi与PCr的峰高比等于1时给予复氧,发现复氧时Pi立即降低且pH立即升高的小鼠可以恢复,反之则不可恢复,表明Pi和pH反映了大脑缺氧损伤程度.     

Phosphorus-31 MR spectroscopic imaging (MRSI) of normal and pathological human brains.

The goals of this study were to evaluate 31P MR spectroscopic imaging (MRSI) for clinical studies and to survey potentially significant spatial variations of 31P metabolite signals in normal and pathological human brains. In normal brains, chemical shifts and metabolite ratios corrected for saturation were similar to previous studies using single-volume localization techniques (n = 10; pH = 7.01 +/- 0.02; PCr/Pi = 2.0 +/- 0.4; PCr/ATP = 1.4 +/- 0.2; ATP/Pi = 1.6 +/- 0.2; PCr/PDE = 0.52 +/- 0.06; PCr/PME = 1.3 +/- 0.2; [Mg2+]free = 0.26 +/- 0.02 mM.) In 17 pathological case studies, ratios of 31P metabolite signals between the pathological regions and normal-appearing (usually homologous contralateral) regions were obtained. First, in subacute and chronic infarctions (n = 9) decreased Pi (65 +/- 12%), PCr (38 +/- 6%), ATP (55 +/- 6%), PDE (47 +/- 9%), and total 31P metabolite signals (50 +/- 8%) were observed. Second, regions of decreased total 31P metabolite signals were observed in normal pressure hydrocephalus (NPH, n = 2), glioblastoma (n = 2), temporal lobe epilepsy (n = 2), and transient ischemic attacks (TIAs, n = 2). Third, alkalosis was detected in the NPH periventricular tissue, glioblastoma, epilepsy ipsilateral ictal foci, and chronic infarction regions; acidosis was detected in subacute infarction regions. Fourth, in TIAs with no MRI-detected infarction, regions consistent with transient neurological deficits were detected with decreased Pi, ATP, and total 31P metabolite signals. These results demonstrate an advantage of 31P MRSI over single-volume 31P MRS techniques in that metabolite information is derived simultaneously from multiple regions of brain, including those outside the primary pathological region of interest. These preliminary findings also suggest that abnormal metabolite distributions may be detected in regions that appear normal on MR images.     

Iterative reconstruction of radially-sampled 31P bSSFP data using prior information from 1H MRI

The purpose of this study is to improve direct phosphorus (³¹P) MR imaging. Therefore, 3D density-adapted radially-sampled balanced steady-state free precession (bSSFP) sequences were developed and an iterative approach exploiting additional anatomical information from hydrogen (¹H) data was evaluated. Three healthy volunteers were examined at B₀ = 7 T in order to obtain the spatial distribution of the phosphocreatine (PCr) intensities in the human calf muscle with a nominal isotropic resolution of 10 mm in an acquisition time of 10 min. Three different bSSFP gradient schemes were investigated. The highest signal-to-noise ratio (SNR) was obtained for a scheme with two point-reflected density-adapted gradients. Furthermore, the conventional reconstruction based on a gridding algorithm was compared to an iterative method using an ¹H MRI constraint in terms of a segmented binary mask, which comprises prior knowledge. The parameters of the iterative approach were optimized and evaluated by simulations featuring ³¹P MRI parameters. Thereby, partial volume effects as well as Gibbs ringing artifacts could be reduced. In conclusion, the iterative reconstruction of ³¹P bSSFP data using an ¹H MRI constraint is appropriate for investigating regions where sharp tissue boundaries occur and leads to images that represent the real PCr distributions better than conventionally reconstructed images.     

Single excitation multiple image RARE (SEMI-RARE): ultra-fast imaging of static and flowing systems

This paper describes the development and application of a new rapid, full k-space acquisition imaging pulse sequence based on the rapid acquisition with relaxation enhancement (RARE) methodology. We have termed this pulse sequence single excitation multiple image RARE (SEMI-RARE). We demonstrate the application of SEMI-RARE to the visualisation of a static liquid phantom and it is shown that up to 120 images can be acquired from a single excitation. By exploiting the inherent relaxation and diffusion contrast within the series of images, the SEMI-RARE provides an ultra-fast method for characterising the spatial distribution of chemical species and phases within complex systems. The pulse sequence is then applied to the study of single- and two-phase flow in a single narrow tube of inner diameter 2.9mm. In particular, it is shown that 8 two-dimensional slice-selective images for two-phase bubble-train flow in a single tube can be acquired from a single excitation at effective echo-times of 37, 109, 181, 253, 325, 397, 469, and 541ms. The visualisation enables the determination of gas/liquid bubble sizes and velocities during two-phase flow. We also report the first direct evidence, obtained from magnetic resonance measurements, of liquid re-circulation zones associated with bubble-train flow. The robustness of the SEMI-RARE technique makes it an attractive fast imaging technique for the study of multi-phase flow phenomena, which are often characterised by large variations in magnetic susceptibility, and are of widespread interest in chemical engineering.     

On neglecting chemical exchange effects when correcting in vivo (31)P MRS data for partial saturation

Signal acquisition in most MRS experiments requires a correction for partial saturation that is commonly based on a single exponential model for T(1) that ignores effects of chemical exchange. We evaluated the errors in (31)P MRS measurements introduced by this approximation in two-, three-, and four-site chemical exchange models under a range of flip-angles and pulse sequence repetition times (T(R)) that provide near-optimum signal-to-noise ratio (SNR). In two-site exchange, such as the creatine-kinase reaction involving phosphocreatine (PCr) and gamma-ATP in human skeletal and cardiac muscle, errors in saturation factors were determined for the progressive saturation method and the dual-angle method of measuring T(1). The analysis shows that these errors are negligible for the progressive saturation method if the observed T(1) is derived from a three-parameter fit of the data. When T(1) is measured with the dual-angle method, errors in saturation factors are less than 5% for all conceivable values of the chemical exchange rate and flip-angles that deliver useful SNR per unit time over the range T(1)/5 < or = T(R) < or = 2T(1). Errors are also less than 5% for three- and four-site exchange when T(R) > or = T(1)(*)/2, the so-called "intrinsic" T(1)'s of the metabolites. The effect of changing metabolite concentrations and chemical exchange rates on observed T(1)'s and saturation corrections was also examined with a three-site chemical exchange model involving ATP, PCr, and inorganic phosphate in skeletal muscle undergoing up to 95% PCr depletion. Although the observed T(1)'s were dependent on metabolite concentrations, errors in saturation corrections for T(R) = 2 s could be kept within 5% for all exchanging metabolites using a simple interpolation of two dual-angle T(1) measurements performed at the start and end of the experiment. Thus, the single-exponential model appears to be reasonably accurate for correcting (31)P MRS data for partial saturation in the presence of chemical exchange. Even in systems where metabolite concentrations change, accurate saturation corrections are possible without much loss in SNR.     

大鼠急性缺血心肌31P磁共振波谱的基础研究

利用³¹P磁共振波谱（MRS）检测了急性缺血心肌组织提取物中高能磷酸化合物的变化. 方法：成年SD大鼠在心肌梗塞后0、5、 20、45 min后进行取材,梗塞区、边缘区及正常区的心肌组织经高氯酸萃取后进行高分辨MRS检测. 结果：梗塞区,缺血5 min PCr/Pi比值下降到对照组的12 ％;20 min ATP/Pi 比值下降至0.05,Pi/EPP比值上升至0.8;45 min 梗塞区PDE/ATP上升至1.93,与45 min心肌的不可逆损伤超微结构相吻合. 边缘区各代谢产物出现改变的程度要小于梗塞区,大于正常区. 正常区也有能量代谢的改变. 结论：心肌组织的³¹P MRS能够反映心肌缺血后心肌不同部位的动态能量代谢改变. PDE/ATP是判断心肌不可拟性损伤的可靠指标.     

活体动物代谢过程的31P NMR研究——方法与初步结果

利用表面线圈探头测得了小鼠大脑,大腿肌肉和肝脏的体内³¹P NMR谱图。观察到PCr,ATP,PME,PDE,P_i等化合物的共振峰,并确定了各谱峰的化学位移。由大脑的P_i化学位移计算得到其细胞内pH值为7.15.用差谱方法解决了因定位不准而造成的肝脏谱图不纯。观察了小鼠大脑在缺氧状态下的代谢变化过程。当O₂浓度降至2%时,PCr开始下降,降到1%时,P_i明显升高。从空气变化到1%的O₂含量,致使小鼠死亡,小鼠大脑的pH值从7.16降到6.46。     

Chemical exchange magnetic resonance imaging (CHEMI)

Systems investigated with NMR spectroscopy are sometimes heterogeneous with respect to chemical composition, rates of chemical exchange, and other properties influencing magnetic resonance parameters. A method was developed to spatially encode reaction kinetic information and produce NMR images sensitive to chemical exchange. A modified spin-echo pulse sequence was used to allow chemical shift-selective imaging and chemical exchange encoding. 1H and 31P images with microscopic resolution were obtained which yielded chemical exchange as a function of position. Chemical exchange images of the base-catalyzed proton exchange of acetylacetone and of the enzyme-catalyzed 31P transfer between PCr and ATP were obtained at 8.4 T in phantoms at 360 and 146 MHz, respectively. These images demonstrate a means of investigating kinetic heterogeneity and compartmentalization of reactions that are important in the study of both living and non-living systems.     

鼠S180肉瘤的体内31P MRS研究

利用表面线圈³¹P NMR研究了小鼠S180肉瘤生长过程中能量代谢和磷脂类变化的特点.结果发现:随着肿瘤体积的增大,(1)Pi和PME升高;(2)PCr降低,在肿瘤体积较大时常检测不到;(3)β-NTP(通常用来表示ATP的量)变化较小;(4)PDE波动性较大;(5)PCr/Pi和β-NTP/Pi比值均下降,且PCr/Pi比β-NTP/Pi下降得快;(6)PME/β-NTP比值升高;(7)肿瘤pH下降,且与PCr/Pi、β-NTP/Pi或(PCr+β-NTP)/Pi比值有相关性.讨论了与这些参数变化相关联的生物学意义.     

Observations of energy metabolism in neuroectodermal tumors using in vivo 31P-NMR

The energy metabolism of living tumors in rats and hamsters were investigated by obtaining in vivo 31P-NMR spectra, and the effects of chemotherapy on tumors were evaluated by observing the changes of these spectra. Tumor cells of rat glioma, human glioblastoma and human neuroblastoma were inoculated subcutaneously in the lumbar region of the animals. After the tumor grew to over 1.5 cm in diameter, in vivo 31P-NMR spectrum data was obtained selectively from the tumor with a TMR-32 spectrometer (Oxford Research Systems, U.K.). Several peaks (ATP, inorganic phosphate (Pi), phosphodiesters and phosphomonoesters (PME) were observed in the tumors. The heights of these peaks varied widely corresponding to the tumor growth. However, the spectrum pattern of each tumor in an active stage was found to be essentially the same regardless of histological type or tumor origin. The phosphocreatine (PCr) peak was small, ATP and PME peaks were large and tissue pH calculated from the chemical shift of Pi was low in each tumor group. After intravenous injection of a large dose of a chemotherapeutic agent, ATP peaks decreased and the Pi peak increased gradually, resulting in a dominant Pi peak pattern after several hours in all groups. With lower drug doses, spectrum changes were temporarily seen in the tumors. These findings indicated that drugs with a high dose have a selective and a direct action on the energy metabolism of tumor tissues. In vivo 31P-NMR spectra measurement is very valuable not only to investigate the energy metabolism in tumor tissue but also to evaluate the effects of chemotherapy on the tumor.     

急性低氧大鼠脑31P核磁共振波谱研究

³¹P磁共振波谱是目前唯一可以用作在体无损伤的检测细胞水平能量代谢变化的非侵入性技术,可测得脑内多种能量代谢产物.目的：急性低氧大鼠脑组织的³¹P MRS检测.方法：(1)20只成年SD大鼠分为4组：低氧0min(对照),5min,10min,15min后,迅速液氮冷冻;(2)将脑组织研碎后,加入高氯酸(PCA),冷冻干燥;(3)将提取物用0.5mL D\-2O溶解后进行MRS检测.结果：(1)急性低氧早期即引起³¹P MRS中PCr和ATP峰降低,ADP和Pi峰增高,PCr/Pi和ATP/Pi降低,而ADP/ATP增高.可交换磷池(EPP)中PCr的正常值为42.4%,低氧5min后降到28.9%, ATP从33.8%降到19.2%,Pi从17.7%升到42.0%.(2)急性低氧时³¹P MRS中脑内磷酯分解代谢产物GPC、GPE含量增加,说明低氧早期脑内即有膜磷酯的分解增加.结论：³¹P磁共振波谱可用于脑低氧性疾病的诊断,我们波谱中最敏感的指标是PCr/Pi和ATP/Pi,尤其早期降低更为显著.     

Considerations for brain pH assessment by 31P NMR

Recently in vivo NMR spectroscopy has been used to measure brain pH non-invasively. Both the inorganic orthophosphate (Pi) chemical shift (delta) and the difference between the chemical shifts of phosphocreatine (PCr) and Pi(delta delta PCr-Pi) have been proposed as indicators of brain pH. However, the precise delta of Pi may be difficult to determine under normoxic conditions as is the delta of PCr under hypoxic/ischemic conditions. Ideally one needs a NMR delta parameter that: (1) linearly changes between pH 6.0-8.0, (2) is either relatively unaffected or predictably affected by cations (e.g., Mg2+) other than H+, and that (3) comes from readily observable 31P NMR resonances whose delta's can be accurately assessed under all physiological conditions. Therefore, we undertook a systematic 31P NMR study of the pH and Mg2+ titration curves for 16 phosphorus-containing metabolites observed in brain by 31P NMR. On the basis of the titration curves, the delta delta's for PCr-Pi, phosphoethanolamine (PE)-Pi, and PCr-PE fulfill criteria (1) and (2), but not criterion (3). However, the delta delta of ATP gamma-alpha fulfills all three criteria and potentially provides information on the intracellular Mg2+ concentration.     

离体心脏的31P NMR谱

³¹P NMR谱自70年代后期开始被用于离体心脏中含磷化合物代谢的动态研究.^3lP NMR谱不仅可以鉴定心肌组织中浓度较高的含磷化合物,即ATP、磷酸肌酸和无机磷酸盐,而且可提供有关这些化合物化学环境(包括pH和Mg²⁺)和细胞内分布的信息.利用这一非损伤性的定量分析方法,可连续观测心肌的代谢并可同时测定离体心脏的机械功能.利用饱和转移技术还能对完整心脏中肌酸激酶和腺苷酸激酶反应的速率加一测定.本文综述介绍了近年来进行离体灌流心脏^3lP NMR谱测定的实验方法以及这一技术所提供的各种信息.     

A 3D image interleaving method for real-time autostereoscopic display based on GPU

Multiview autostereoscopic systems display three-dimensional (3D) images interleaved from parallax images to provide adequate viewing zones for viewers. A 3D image interleaving method based on parallel processing with Graphic Processing Unit (GPU) is proposed to accelerate the image interleaving for real-time autostereoscopic displays. The proposed method is implemented with Direct3D Application Programming Interface (API) library. Masks used to interleave the 3D images are generated according to some particular principles. Both multiple texture blending and alpha blending operations are used to interleave a 3D image. The experiments prove that high interleaving efficiency and good stereoscopic sense can be obtained. The proposed method meets the requirement of real-time multiview autostereoscopic displays and avoids extra shader program.