From the *Department of Nuclear Medicine, Taichung Veterans General Hospital; †Institute of Radiological Science, Central Taiwan University of Science and Technology; ‡Division of Rheumatology, Taichung Veterans General Hospital; and §Department of Emergency, Show Chwan Memorial Hospital, Taiwan, Republic of China.
Clin Nucl Med. 2016 Jun;41(6):442-6. doi: 10.1097/RLU.0000000000001108.
Renal biopsy is crucial for management of lupus nephritis. However, it is invasive and can cause bleeding and infection. In our previous study, we developed a semiquantitative method for gallium renal imaging and demonstrated a good correlation between the left kidney-to-spine ratio (K/S ratio) and the results of renal biopsy. However, the accuracy of left K/S ratio is compromised by the variation of spinal gallium uptake, especially in patients with extraordinarily high or low gallium uptakes in the spine. In this study, we developed an absolute quantitative method and compared the results of quantitative gallium images, semiquantitative gallium images, visual methods, and renal biopsies.
Thirty-four patients with lupus nephritis were enrolled and underwent renal biopsy to determine activity index (AI) and chronicity index. A delayed 48-hour gallium scan was also performed and interpreted by visual, semiquantitative, and absolute quantitative methods. For absolute quantitative analysis, a standard solution with activities of approximately 555 KBq (15 μCi) was prepared and poured into a 5-mL tube, which was placed close to the patient. ROIs were drawn around the outer edge of the left kidney as well as around the outer edges of the standard. A kidney uptake index (KUI) was calculated, and the results were compared with K/S ratio, visual grading, and renal biopsies.
Kidney uptake index had the best correlation with AI among the 3 methods using Spearman rank correlation test. The Spearman R values were 0.78, 0.71, and 0.61 for KUI, K/S ratio and visual grading, respectively. Chronicity index did not correlate well with the results of any of the 3 methods. In addition, AI was significantly higher in patients with a KUI equal to or greater than 1.5, when compared with patients with a KUI lower than 1.5 (P = 0.00001 by Mann-Whitney U test). Using a K/S ratio of 0.95 as a cutoff value, AI also showed a statistically significant difference with P = 0.0001. When a visual grading of 2 was used as a cutoff value, P = 0.0008. The difference in AI was most significant when the statistical value was based on the KUI.
The KUI showed better correlation with the results of renal biopsy than the K/S ratio and the visual grading. We suggest that the KUI from the absolute quantitative renal gallium scintigraphy may be a useful parameter for evaluating the disease activity in lupus nephritis.
肾活检对于狼疮肾炎的治疗至关重要。但它是一种有创性的检查，可能会导致出血和感染。在我们之前的研究中，我们开发了一种半定量的肾锝扫描方法，并证明了左肾-脊柱比值（K/S 比值）与肾活检结果之间存在良好的相关性。然而，脊柱摄取锝的变化会影响左 K/S 比值的准确性，尤其是在脊柱摄取锝量极高或极低的患者中。在这项研究中，我们开发了一种绝对定量的方法，并比较了定量锝图像、半定量锝图像、视觉方法和肾活检的结果。
我们招募了 34 例狼疮肾炎患者，进行肾活检以确定活动指数（AI）和慢性指数。还进行了延迟 48 小时的锝扫描，并通过视觉、半定量和绝对定量方法进行解释。对于绝对定量分析，我们制备了一个含有约 555KBq（15μCi）活性的标准溶液，并将其倒入一个 5ml 的试管中，将该试管放置在患者附近。在左肾的外缘和标准溶液的外缘画 ROI，计算肾摄取指数（KUI），并将结果与 K/S 比值、视觉分级和肾活检进行比较。
Spearman 秩相关检验显示，在这 3 种方法中，肾摄取指数与 AI 的相关性最好。Spearman R 值分别为 0.78、0.71 和 0.61，用于 KUI、K/S 比值和视觉分级。慢性指数与这 3 种方法的结果均无良好相关性。此外，与 KUI 小于 1.5 的患者相比，KUI 等于或大于 1.5 的患者的 AI 显著更高（Mann-Whitney U 检验，P = 0.00001）。使用 K/S 比值为 0.95 作为截断值，P = 0.0001 时 AI 也有统计学差异。当使用视觉分级 2 作为截断值时，P = 0.0008。基于 KUI 时，AI 的差异最为显著。
肾摄取指数与肾活检结果的相关性优于 K/S 比值和视觉分级。我们建议，绝对定量肾锝扫描的肾摄取指数可能是评估狼疮肾炎疾病活动度的有用参数。
