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| A correlative study of semi-quantitative bone scanning and MRI on osteosarcoma |
| FENG Jin, LOU Lu-xin, ZHANG Lian-na, YANG Fang, CHENG Xiao-guang |
| Beijing Jishuitan Hospital, Beijing 100035, China |
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Abstract Objective: To find a semi-quantitative bone imaging method by comparison with MRI in order to measure bone invasion of limb osteosarcoma accurately. Methods: 23 patients diagnosed with osteosarcoma by histology were included. Preoperative whole body bone scan and partial magnetic resonance imagings(MRI) were analyzed retrospectively. Threshold method of radioactive count changing-rate on bone scan was designed. The radioactive count changing-rate R=(T-NT)/NT×100% was converted into T=R×0.01×NT+NT. By assuming multiple R values, different T values of tumor boundary were obtained. Visual measurements on bone scintigraphy and MRI T1WI were compared with pathological boundaries as the gold standard. Paired t-test was used to analyze the accuracy. The intraclass correlation coefficient was used to evaluate the repeatability in two observers and two times of measurements. Results: There were significant differences between bone scanning visual method and pathologic measurements(t=-3.041, P=0.006<0.01). There was no significant difference between bone scan threshold method and pathologic range, with radioactive count changing-rate R=80%(t=-1.519, P=0.143>0.05), R=100% (t=-0.642, P=0.527>0.05), R=120%(t=0.192, P=0.850>0.05）, R=140%(t=1.178, P=0.252>0.05). When R=100% and 120%, average difference was the minimum． The differences between MRI T1WI measurements and pathologic measurements showed no difference(t=-3.041, P=0.006<0.01). In cases with varied signal intensities on MRI, the measurements of MRI and pathology were matched in the plane which was the closest to bone scan semi-quantitative method(R=100% and R=120%). In bone scanning visual method, there was significant difference of osteosarcoma extents between two different measurers(P<0.05), and there was no significant difference between two times of the same observer(P>0.05). In bone scan threshold method, measurements of two observers and two different times of the same observer showed high consistency(ICC>0.900). Conclusion: MRI is dominant in the evaluation of intramedullary invasion in osteosarcoma. In assessing range of far-articular bone invasion, threshold method of radioactive count changing-rate on bone scan is more objective and accurate than visual method. Bone scintigraphy helps to determine the measurement plane on MRI T1WI in cases with varied signal intensities.
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Received: 13 October 2014
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2015, Vol. 26 
