Diffusion weighted MRI of osteoid osteomas: Higher ADC values after radiofrequency ablation.
Eur J Radiol 2016;
85:1284-8. [PMID:
27235875 DOI:
10.1016/j.ejrad.2016.03.028]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 03/15/2016] [Accepted: 03/29/2016] [Indexed: 11/25/2022]
Abstract
PURPOSE
Feasibility of diffusion weighted MRI (DWI) pre- and post-radiofrequency ablation (RFA) in patients with osteoid osteoma (OO).
MATERIAL AND METHODS
Ten patients (1 female, 24±9years) received RFA of OO (mean size 8.7±3.2mm). Two OO recurred, in one of these a second RFA was performed. A 1.5T DWI (b=50, 400, and 800s/mm(2)) and a fat saturated DCE MRI were obtained the day before and after RFA. In DWI, the mean apparent diffusion coefficient (ADC) was recorded. With DCE MRI, signal-to-noise ratio, contrast-to-noise ratio, absolute signal intensity (SI), relative SI, and SI ratio were documented. All parameters were compared pre- and post-RFA using paired Wilcoxon rank test.
RESULTS
ADC values were significantly higher post-ablation, 1.6±0.5μm(2)/ms versus 1.3±0.6μm(2)/ms (p<0.05). Perfusion was significantly reduced after ablation [SNR, CNR, SI, %SI, and SI OO/SI muscle]; post-RFA: 55±13, 27±20, 757±534, 102±16, and 1.6±0.2; pre-RFA: 88±37, 65±22, 1038±755, 226±51, and 2.0±0.5 (p<0.05).
DISCUSSION
DWI is feasible in OO. ADC values increased and contrast enhancement decreased after RFA of OO. This may be explained by RFA-induced necrosis and devascularization.
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