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.
Key words
Osteosarcoma /
Magnetic resonance imaging /
Radionuclide imaging
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FENG Jin;LOU Lu-xin;ZHANG Lian-na;YANG Fang;CHENG Xiao-guang.
A correlative study of semi-quantitative bone scanning and MRI on osteosarcoma[J]. Journal of China Clinic Medical Imaging. 2015, 26(5): 349-354
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