Histomorphometryof the vertebra and its correlations with MRI signal intensity in rabbits with fluoride treatment / 中华骨科杂志

ABSTRACT

Objective To analyze histomorphometrical characteristics of the bone and bone marrow tissues of the lumbar vertebrae in rabbits with fluoride treatment,and its correlation with signal intensity of MRI.Methods Forty New Zealand albino rabbits aged three months old were randomly divided into fluoride exposure of 30 cases and control of 10 cases,male and female,half each.One hundred milligrams of sodium fluoride were added to the municipal water each liter (fluoride content 100 mg/L) as drinking waterto fluorine for 180 days.Twenty-four of 30 cases with fluoride exposure had complete data (male10 casesand female14 cases).The same municipal water was used as control drinking water (fluoride content ＜ 0.9 mg/L).Eight of 10 cases with control had complete data (male andfemale in half).Twenty-four cases with fluoride treatment and complete data were classified into sensitive and resistant type according to the MRI signal intensity of the lumbar vertebra.Histomorphometrics of the vertebra and its correlation with the MRI signal intensity,and sensitivity in early diagnosis of osteofluorosis and feasibility of susceptibility to osteofluorosis detected with MRI were analyzed.Results Theratios of trabecular bone volume (BV),hematopoietic cell volume (HV) and fluid volume (FV) in bone marrow tissue to total cavernous tissue volume (TT) in group with fluoride treatment were 18.3％±2.6％,45.2％±6.0％ and 10.4％±5.7％ respectively.These were 14.5％±2.8％,36.3％±7.3％ and 6.2％±2.1％ in control group respectively.These parameters in fluoride group were significantly increased compared to control group.The ratio 26.0％± 8.0％ of adipocyte volume (AV) to TV in fluoride group was significantly lower than that 43.3％±5.6％ in control group.Two of 24 cases with fluoride exposure (8.3％,2/24) were sensitive and the remaining 22 (91.7％,22/24) were in resistance.The valuesof BV/TT,HV/TV and FV/TV were considered to be sensitive,resistant and control from large to small,while AV/TV value were opposite.A comparison resuhs of signal intensity in MRI showed that vertebra T1WI contrast to noise ratio (CNR) in the sensitive was the minimum (3.0±0.8),followed by resistance (21.3±3.8) andmaximum in the control (28.3±3.1),but CNR of FsT2WIwas opposite.There were positive associations between T1WI and AV/TV,FV/TV and BV/TV,and between FsT2WI and FV/TV and BV/ TV.There were inverse associationsbetween FsT2WI and AV/TV.Theoptimal threshold value of the vertebra T1WI CNR was 23.2 or lessin early diagnosis of skeletal fluorosis,with sensitivity of 83.3％ and specificity of 100％.FsT2WI was 5.7 or more,with sensitivity of 45.8％ and specificity of 100％.Conclusion The pathogenesis of osteofluorosis is relative to changes in bone marrow microenvironment and cells number in bone marrow tissue,and is correlated to MRI signal intensity.