Poulton T B, Murphy W D, Duerk J L, Chapek C C, Feiglin D H
Department of Radiology, Aultman Hospital, Canton, OH 44710-1702.
AJR Am J Roentgenol. 1993 Dec;161(6):1217-21. doi: 10.2214/ajr.161.6.8249729.
Conversion of bone marrow in the extremities from red to yellow is a normal maturation process. Marrow reconversion is present when expected yellow marrow is replaced with active red marrow, and it tends to occur at times of physiologic stress. The significance of this finding on MR imaging is not always clear. Accordingly, we studied the prevalence of bone marrow reconversion in adults undergoing MR imaging of the knee for reasons other than marrow disorders. Possible relationships between marrow reconversion and age, sex, weight, and smoking were sought.
Fifty-nine outpatients over 24 years of age who had no evidence of hematopoietic disorders and for whom MR images of the knee were available for review were selected for study. Patients younger than 25 years old were eliminated to ensure that all patients in the study were old enough to have achieved normal adult marrow conversion. The 59 subjects were classified according to their smoking histories. Twenty-eight were nonsmokers, 10 were intermediate smokers, and 21 were heavy smokers. The MR images were classified as showing either red marrow (reconverted from yellow to red) or yellow marrow (converted) by two independent observers who had no knowledge of the patients' smoking histories.
MR images of six heavy smokers, two intermediate smokers, and one nonsmoker showed evidence of reconversion. A statistically significant association between marrow reconversion and heavy smoking (p = .02) was found. Reconversion also was found to be more prevalent in patients less than 39 years old and in obese women who smoked. No association was found between weight, sex, or obese male smokers and reconversion.
Our results show marrow reconversion at the knee is most prevalent in heavy smokers, younger patients, and especially obese women who smoke heavily. In these patients, marrow reconversion can be a normal finding on MR imaging. In other patients, other causes should be considered.
四肢骨髓由红髓向黄髓的转变是一个正常的成熟过程。当预期的黄髓被活跃的红髓取代时，就会出现骨髓再转变，且往往发生在生理应激时期。这一发现在磁共振成像（MR）上的意义并不总是明确的。因此，我们研究了因骨髓疾病以外的原因接受膝关节MR成像的成年人中骨髓再转变的发生率。探讨了骨髓再转变与年龄、性别、体重和吸烟之间可能的关系。
选取59例年龄超过24岁、无造血系统疾病证据且有膝关节MR图像可供复查的门诊患者进行研究。排除25岁以下的患者，以确保研究中的所有患者年龄足够大，已完成正常的成人骨髓转变。59名受试者根据吸烟史进行分类。28名是非吸烟者，10名是中度吸烟者，21名是重度吸烟者。由两名不了解患者吸烟史的独立观察者将MR图像分类为显示红髓（由黄髓再转变为红髓）或黄髓（已转变）。
6名重度吸烟者、2名中度吸烟者和1名非吸烟者的MR图像显示有再转变的证据。发现骨髓再转变与重度吸烟之间存在统计学显著关联（p = 0.02）。还发现再转变在39岁以下的患者以及吸烟的肥胖女性中更为普遍。未发现体重、性别或肥胖男性吸烟者与再转变之间存在关联。
我们的结果表明，膝关节骨髓再转变在重度吸烟者、年轻患者中最为普遍，尤其是吸烟的肥胖女性。在这些患者中，骨髓再转变在MR成像上可能是正常表现。在其他患者中，则应考虑其他原因。
