Faber T L, Raghunath N, Tudorascu D, Votaw J R
Department of Radiology, Emory University Hospital, 1364 Clifton Road, N.E. Atlanta, GA 30322, USA.
Phys Med Biol. 2009 Feb 7;54(3):797-811. doi: 10.1088/0031-9155/54/3/021. Epub 2009 Jan 9.
Image quality is significantly degraded even by small amounts of patient motion in very high-resolution PET scanners. Existing correction methods that use known patient motion obtained from tracking devices either require multi-frame acquisitions, detailed knowledge of the scanner, or specialized reconstruction algorithms. A deconvolution algorithm has been developed that alleviates these drawbacks by using the reconstructed image to estimate the original non-blurred image using maximum likelihood estimation maximization (MLEM) techniques. A high-resolution digital phantom was created by shape-based interpolation of the digital Hoffman brain phantom. Three different sets of 20 movements were applied to the phantom. For each frame of the motion, sinograms with attenuation and three levels of noise were simulated and then reconstructed using filtered backprojection. The average of the 20 frames was considered the motion blurred image, which was restored with the deconvolution algorithm. After correction, contrast increased from a mean of 2.0, 1.8 and 1.4 in the motion blurred images, for the three increasing amounts of movement, to a mean of 2.5, 2.4 and 2.2. Mean error was reduced by an average of 55% with motion correction. In conclusion, deconvolution can be used for correction of motion blur when subject motion is known.
在超高分辨率正电子发射断层扫描(PET)扫描仪中,即使患者有少量运动,图像质量也会显著下降。现有的利用从跟踪设备获得的已知患者运动的校正方法,要么需要多帧采集、对扫描仪的详细了解,要么需要专门的重建算法。已经开发出一种反卷积算法,该算法通过使用最大似然估计最大化(MLEM)技术,利用重建图像来估计原始的未模糊图像,从而缓解了这些缺点。通过对数字霍夫曼脑模型进行基于形状的插值创建了一个高分辨率数字模型。对该模型应用了三组不同的20种运动。对于运动的每一帧,模拟了带有衰减和三个噪声水平的正弦图,然后使用滤波反投影进行重建。将这20帧的平均值视为运动模糊图像,并使用反卷积算法进行恢复。校正后,对于三种增加的运动量,对比度从运动模糊图像中的平均值2.0、1.8和1.4分别增加到平均值2.5、2.4和2.2。通过运动校正,平均误差平均降低了55%。总之,当已知受检者运动时,反卷积可用于校正运动模糊。