S-MRI Score as a Simple Method To Assess Bone Marrow Involvement in Gaucher Disease.

Background: Semiquantitative MRI is a very useful procedure to evaluate the bone marrow burden in Gaucher disease (GD). Score systems have been applied to obtain a parameter to evaluate the severity of bone disease. Our purpose was applied a simple, reproducible and accurate score to evaluate completely bone marrow involvement in GD patients

Patients and Methods: MRI was performed in spine, pelvis and femora at diagnosis in 54 adult consecutively diagnosed as GD1, 61.1% females. Three MRI patterns and punctuation in each location were defined: normal: 0; non-homogeneous infiltration subtypes reticular:

1. mottled:

2. diffuse:

3. and homogeneous infiltration:

4. This score was called as Spanish-MRI (S-MRI):

Two independent observers applied the S-MRI and Bone Marrow Burden (BMB) score and to compare the differences between both systems by using non parametric Mann-Whitney test. Correlation rank test was calculated.

Results: In 46 patients (85.2%) bone involvement was observed, 39 (72.3%) has spine affected, 35 (64.8%) pelvis and 33 (61.2%) femorae, 14 patients had bone infarcts, 14 avascular necrosis, 2 vertebral fracture and 2 bone crisis. Correlation analysis between S-MRI and BMB was significant (r2:.675; p= .0001). No evidence of correlation was observed between CT activity and S-MRI and neither between CT activity and BMB. We have analysed the relationship between the patient genotype and bone infiltration according S-MRI, the location and complications. Patients with genotype N370S/rare allele (n=22), have more bone complications (90.1%) Infarcts: 9; AVN: 8, Bone crisis: 2; and vertebral fracture: 1. The mean S-MRI in this group was 7.9. Patients N370S/L444P (n=16) were the higher group with spine involvement (87.5%) mean S-MRI: 8.7. By contrast all patients homozygous for N370S (n=8), have femorae involvement, but a low S-MRI 7.5. The remaining 5 patients have complex genotypes (rare/rare), nevertheless they are not significant data(p=.335, p=.795)

Conclusions: S-MRI is a simple method that provides useful information to evaluate bone infiltration and detect silent complications. Our results were correlated with the BMB score with higher sensitivity and specificity and provide accuracy to classify the degrees of the bone disease

This work has been performed with the collaboration of the Spanish Group on Gaucher Disease and partially sponsored by a grant from FEETEG.