Background: Semi-quantitative evaluation of Modic changes (MCs) has recently been proposed as a way to\nstandardise and increase repeatability of clinical studies. This study is aimed at developing semi-quantitative\nmeasures of enhancement, given by contrast agent injection, on T1-weighted images in MCs, and to investigate\ntheir reliability and relation with MC types.\nMethods: Thirty-seven subjects suffering from low back pain underwent T1-weighted and T2-weighted turbo\nspin-echo sequences. Five minutes after the injection of a paramagnetic contrast agent, a second T1-weighted\nsequence was acquired. Regions of interest (ROIs) corresponding to MCs were selected manually on the\nunenhanced image; control ROIs in the ââ?¬Å?healthyââ?¬Â bone marrow were selected. For each ROI, the mean signal\nintensity (SI) of unenhanced pixels and the mean absolute and normalised difference in SI between\nunenhanced and contrast-enhanced pixels values were calculated.\nResults: A total of 103 MCs were recognised and 61 were semi-quantitatively analysed: 16 type I, 34 type II\nand 11 type I/II. Regarding controls, MCs I showed a lower SI on the unenhanced T1-weighted images and a\nmarked contrast enhancement (CE); MCs II showed a higher SI than controls on unenhanced images and a\nlower or comparable CE; and MCs I/II presented an intermediate SI on the unenhanced images and a marked\nCE. Inter-rater and intra-rater agreements were found to be excellent or substantial.\nConclusions: Semi-quantitative measurements could differentiate MC types in terms of unenhanced SI and of\nCE with respect to ââ?¬Å?healthyââ?¬Â bone marrow.
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