MRI of Residual Red Bone Marrow in the Distal Femur of Healthy Subjects

Abstract

SummaryBackroundThe purpose of our study is to examine the correlation of the residual red bone marrow areas of distal femoral metaphysis with the age, gender, weight and hemoglobin (hgb) values; evaluate the results, and comprehend the importance of these residual areas in the light of the results.Material/Methods140 nonsmoking patients between the ages of 26 and 72 (92 women, 48 men) who had knee MR examinations were included in the study. The residual red bone marrow areas in the distal femoral metaphysis in MR images were examined by a radiologist. The areas were separated into grades according to their sizes. The hemoglobin values of the cases were measured. The size of the residual red bone marrow area and the age, gender, weight and hemoglobin values of the cases were compared by using the Tukey and Chi-Square Tests.ResultsAlthough no significant differences were observed between the mean ages, weights and hemoglobin values of the grades, a significant difference was detected between the gender distribution The male group had less residual red bone marrow in the distal femoral metaphysis than the female group (p=0.003).ConclusionsWe observed that the hypointensities due to residual red bone marrow observed in the T1WS of the distal femoral metaphysis are not related with the age, weight and hemoglobin values. No grade 2 and grade 3 patient was detected in male group. We observed that these hypointense areas showed difference according to the gender variable; however, were not affected by the hemoglobin values over certain levels.

Prevalence and Clinical Significance of Residual or Reconverted Red Bone Marrow on Knee MRI

“…We found the prevalence of a definite residual or reconverted RBM (18.8%) to be lower than the prevalence reported previously. Our results were consistent with a more recent study, which reported the prevalence of RBM proliferation to be as low as 20.7% in females and 0% in males, estimated from a smaller sample ( n = 140) than ours, which was recruited from a single centre in Erzincan [ 22 ].…”

“…However, said studies relied on smaller sample sizes selected from hospital patients ( n = 199 and n = 51 respectively) of a wider age range (16–79 and 25–67 years respectively) and did not utilize any (semi-)quantitative scale to grade residual or reconverted RBM. We used a semi-quantitative scoring, following a similar criteria to a more recent study [ 22 ], on a population-based sample of largely healthy young adults. We found the prevalence of a definite residual or reconverted RBM (18.8%) to be lower than the prevalence reported previously.…”

“…Residual or reconverted RBM in the knee was assessed on fat-saturated proton-density-weighted MRI by identifying foci of hypointensity above the distal femoral epiphyseal plate and below the proximal tibial plate. RBM in the femur and tibia were graded on a scale of 0–3 using similar criteria as those in a previous study [ 22 ], where grade 0 indicated 0% occupancy of the metaphysis, grade 1 indicated >0 to <30% occupancy of the metaphysis, grade 2 indicated 30 to 60% occupancy, and grade 3 indicated >60% occupancy ( Figure 1 ). Due to the fact that some presence of grade 1 RBM could be considered a biological variation or doubtful RBM [ 21 ], definite residual or reconverted RBM was defined as grade ≥ 2 in either the femur or the tibia.…”

“…RBM proliferation in the knees of healthy adults in the absence of a malignant cause is postulated to be either a naturally occurring biological variation [ 21 ] or an innocuous physiological response to hematopoietic stress, such as sports anaemia [ 8 , 18 ]. There are conflicting reports on the associations between RBM in adult knees with haemoglobin levels and anaemia [ 22 , 23 ]. Nonetheless, RBM in such cases is unrelated to infiltrative marrow pathology [ 24 ] and is referred to as residual or reconverted RBM [ 22 , 23 ].…”

“…There are conflicting reports on the associations between RBM in adult knees with haemoglobin levels and anaemia [ 22 , 23 ]. Nonetheless, RBM in such cases is unrelated to infiltrative marrow pathology [ 24 ] and is referred to as residual or reconverted RBM [ 22 , 23 ].…”