Nuclear Medicine, Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, 16132 Genova, Italy.
Eur J Nucl Med Mol Imaging. 2012 Aug;39(8):1326-38. doi: 10.1007/s00259-012-2141-9. Epub 2012 May 26.
Despite their relevance in clinical medicine, the extension and activity of the bone marrow (BM) cannot be directly evaluated in vivo. We propose a new method to estimate these variables by combining structural and functional maps provided by CT and PET.
BM extension and glucose uptake were estimated in 102 patients undergoing whole-body PET/CT because of a history of nonmetastatic melanoma. Image analysis assumed that the BM is surrounded by compact bone. An iterative optimization scheme was applied to each CT slice to identify the external border of the bone. To identify compact bone, the algorithm measured the average Hounsfield coefficient within a two-pixel ring located just inside the bone contour. All intraosseous pixels with an attenuation coefficient lower than this cut-off were flagged as 1, while the remaining pixels were set at 0. Binary masks created from all CT slices were thus applied to the PET data to determine the metabolic activity of the intraosseous volume (IBV).
Estimated whole-body IBV was 1,632 ± 587 cm(3) and was higher in men than in women (2,004 ± 498 cm(3) vs. 1,203 ± 354 cm(3), P < 0.001). Overall, it was strictly correlated with ideal body weight (r = 0.81, P = 0.001) but only loosely with measured body weight (r = 0.43, P = 0.01). The average FDG standardized uptake value (SUV) in the thoracic and lumbar vertebrae was 2.01 ± 0.36, Accordingly, intraosseous voxels with SUV ≥ 1.11 (mean spine SUV - 2.5 × SD) were considered as active "red" BM and those with SUV <1.11 as "yellow" BM. Estimated red BM volume was 541 ± 195 ml, with a higher prevalence in the axial than in the appendicular skeleton (87 ± 8 % vs. 10 ± 8 %, P < 0.001). Again, red BM volume was higher in men than in women (7.8 ± 2.2 vs. 6.7 ± 2.1 ml/kg body weight, P < 0.05), but in women it occupied a greater fraction of the IBV (32 ± 7 % vs. 36 ± 10 %, P < 0.05). Patient age modestly predicted red BM SUV, while it was robustly and inversely correlated with red BM volume.
Our computational analysis of PET/CT images provides a first estimation of the extension and metabolism of the BM in a population of adult patients without haematooncological disorders. This information might represent a new window to explore pathophysiology the BM and the response of BM diseases to chemotherapy.
尽管在临床医学中具有相关性，但骨髓（BM）的扩展和活性不能直接在体内进行评估。我们提出了一种新的方法，通过结合 CT 和 PET 提供的结构和功能图来估计这些变量。
由于非转移性黑色素瘤病史，102 名接受全身 PET/CT 的患者进行了 BM 扩展和葡萄糖摄取的评估。图像分析假设 BM 被密质骨包围。对每个 CT 切片应用迭代优化方案来识别骨的外部边界。为了识别密质骨，算法在位于骨轮廓内的两个像素环内测量平均亨氏系数。所有衰减系数低于此截止值的骨内像素都标记为 1，而其余像素设置为 0。从所有 CT 切片创建的二进制掩模因此应用于 PET 数据，以确定骨内体积（IBV）的代谢活性。
估计的全身 IBV 为 1,632 ± 587 cm(3)，男性高于女性（2,004 ± 498 cm(3)比 1,203 ± 354 cm(3)，P < 0.001）。总体而言，它与理想体重（r = 0.81，P = 0.001）严格相关，但与实测体重（r = 0.43，P = 0.01）仅松散相关。胸腰椎的平均 FDG 标准化摄取值（SUV）为 2.01 ± 0.36，因此，SUV ≥ 1.11（平均脊柱 SUV-2.5×SD）的骨内体素被认为是活跃的“红色”BM，SUV <1.11 的被认为是“黄色”BM。估计的红色 BM 体积为 541 ± 195 ml，轴向骨骼的发生率高于四肢骨骼（87 ± 8%比 10 ± 8%，P < 0.001）。同样，男性的红色 BM 体积高于女性（7.8 ± 2.2 比 6.7 ± 2.1 ml/kg 体重，P < 0.05），但女性的红色 BM 体积占 IBV 的比例更大（32 ± 7%比 36 ± 10%，P < 0.05）。患者年龄适度预测红色 BM SUV，而红色 BM 体积与 SUV 呈负相关。
我们对 PET/CT 图像的计算分析提供了对无血液肿瘤疾病的成年患者 BM 扩展和代谢的初步估计。该信息可能代表了一个新的窗口，用于探索 BM 的病理生理学和 BM 疾病对化疗的反应。
