Proton magnetic resonance spectroscopy of musculoskeletal lesions at 3 T with metabolite quantification

Abstract

Purpose

To evaluate whether proton MR spectroscopy (MRS) at 3 T with metabolite quantification is helpful for characterizing musculoskeletal lesions and to reveal whether the concentration of choline is correlated with the pathologic degree of malignancy.

Material and methods

Three-tesla MR images and proton MRS data from 27 consecutive patients with surgically proven musculoskeletal lesions were retrospectively analyzed. We analyzed the presence of choline peaks of malignant tumors according to the degree of malignancies, and we compared them with those of benign lesions. The concentrations of choline calculated by means of the linear combination of model spectra were also compared with respect to the degree of malignancy in each group.

Results

The proton MRS had an overall sensitivity of 68.4%, specificity of 87.5%, positive predictive value of 92.3%, and negative predictive value of 53.8% for the detection of choline compounds. The positive detection rate for choline compounds in the primary malignancy group (53.8%) was lower than that of the metastasis group (100%). All false-negative results were shown in the Grade 1 primary malignancy group. There was no difference in the concentration of choline compounds with respect to the pathologic degree of differentiation.

Conclusion

MR spectroscopy at 3 T with metabolite quantification is a helpful method that shows high specificity (87.5%) in characterizing musculoskeletal lesions, even though its sensitivity (68.4%) is relatively low. Grade 1 primary malignancies of bone and soft tissue tumor have a high potential for producing false-negative results.

Introduction

Proton magnetic resonance (MR) spectroscopy provides information about the metabolism of malignant tumors in clinical settings. The effectiveness of proton MR spectroscopy is mainly based on the detection of elevated levels of choline compounds, which are a marker of active tumors [1]. Although proton MR spectroscopy has shown promise in the evaluation of malignant tumors, choline levels determined by biological aggressiveness may not be as greatly elevated in some cancers [2], [3], [4].

Proton MR spectroscopy has been utilized for the analysis of bone and soft tissue tumors [5], [6], [7]. With the advent of 3 T MRI, it is expected that MR spectra will be obtained with better signal-to-noise ratios (SNRs) with greater certainty. The feasibility of performing proton MR spectroscopy at 3 T for the evaluation of musculoskeletal lesions has been reported recently [8].

In the evaluation of proton MR spectroscopic data, lesion characterization may be performed to detect metabolites. However, the objective and reliable determination of metabolites and their concentrations is necessary [9]. Metabolite concentrations can be estimated by the linear combination of model spectra (LCModel), which is a user-independent spectral fit program, requiring no subjective interactions [10].

In this study, we tried to (1) evaluate whether proton MR spectroscopy at 3 T with metabolite quantification is helpful for characterizing musculoskeletal lesions and (2) reveal whether the concentration of choline is correlated to the pathologic degree of malignancy.