Department of Health Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
Ann Nucl Med. 2010 Oct;24(8):585-91. doi: 10.1007/s12149-010-0401-y. Epub 2010 Aug 4.
We evaluated the partial volume effect in PET/CT images and developed a simple correction method to address this problem.
Six spheres and the background in the phantom were filled with F-18 and we thus obtained 4 different sphere-to-background (SB) ratios. Thirty-nine cervical lymph nodes in 7 patients with papillary thyroid carcinoma (15 malignant and 24 benign) were also examined as a preliminary clinical study. First, we developed recovery coefficient (RC) curves normalized to the maximum counts of the 37-mm sphere. Next, we developed a correction table to determine the true SB ratio using three parameters, including the maximum counts of both the sphere and background and the lesion diameter, by modifying the approximation formula of the RC curves including the point-spread function correction. The full width at half maximum in this formula is estimated with the function of the SB ratio.
In the phantom study, a size-dependent underestimation of the radioactivity was observed. The degree of decline of RC was influenced by the SB ratio. In preliminary clinical examination, the difference in the SUV(max) between malignant and benign LNs thus became more prominent after the correction. The PV correction slightly improved the diagnostic accuracy from 95 to 100%.
We developed a simple table lookup correction method for the partial volume effect of PET/CT. This new method is considered to be clinically useful for the diagnosis of cervical LN metastasis. Further examination with a greater number of subjects is required to corroborate its clinical usefulness.
我们评估了 PET/CT 图像中的部分容积效应，并开发了一种简单的校正方法来解决这个问题。
在体模中，我们将 6 个球体和背景填充了 F-18，从而获得了 4 种不同的球-背景（SB）比。作为初步的临床研究，我们还检查了 7 例甲状腺乳头状癌患者的 39 个颈部淋巴结（15 个恶性和 24 个良性）。首先，我们开发了归一化为 37mm 球体最大计数的恢复系数（RC）曲线。接下来，我们通过修改包括点扩散函数校正的 RC 曲线的近似公式，使用三个参数（球体和背景的最大计数和病变直径）来确定真实的 SB 比，开发了一个校正表。该公式中的半峰全宽是用 SB 比的函数来估计的。
在体模研究中，观察到放射性活度的大小依赖于低估。RC 的下降程度受 SB 比的影响。在初步的临床检查中，校正后良恶性 LNs 的 SUV(max)差异更加明显。PV 校正略微提高了诊断准确率，从 95%提高到 100%。
我们开发了一种简单的 PET/CT 部分容积效应表查找校正方法。这种新方法被认为对诊断颈部淋巴结转移具有临床意义。需要进一步检查更多的对象来证实其临床应用价值。
