title: Convex-Envelope Based Automated Quantitative Approach to Multi-Voxel 1H-MRS Applied to Brain Tumor Analysis.
abstract: BACKGROUND
  Magnetic Resonance Spectroscopy (MRS) can measure in vivo brain tissue metabolism that exhibits unique biochemical characteristics in brain tumors. For clinical application, an efficient and versatile quantification method of MRS would be an important tool for medical research, particularly for exploring the scientific problem of tumor monitoring. The objective of our study is to propose an automated MRS quantitative approach and assess the feasibility of this approach for glioma grading, prognosis and boundary detection.
  
  
  METHODS
  An automated quantitative approach based on a convex envelope (AQoCE) is proposed in this paper, including preprocessing, convex-envelope based baseline fitting, bias correction, sectional baseline removal, and peak detection, in a total of 5 steps. Some metabolic ratios acquired by this quantification are selected for statistical analysis. An independent sample t-test and the Kruskal-Wallis test are used for distinguishing low-grade gliomas (LGG) and high-grade gliomas (HGG) and for detecting the tumor, peritumoral and contralateral areas, respectively. Seventy-eight cases of pre-operative brain gliomas with pathological reports are included in this study.
  
  
  RESULTS
  Cho/NAA, Cho/Cr and Lip-Lac/Cr (LL/Cr) calculated by AQoCE in the tumor area differ significantly between LGG and HGG, with p≤0.005. Using logistic regression combining Cho/NAA, Cho/Cr and LL/Cr to generate a ROC curve, AQoCE achieves a sensitivity of 92.9%, a specificity of 72.2%, and an area under ROC curve (AUC) of 0.860. Moreover, both Cho/NAA and Cho/Cr in the AQoCE approach show a significant difference (p≤0.019) between tumoral, peritumoral, and contralateral areas. The comparison between the results of AQoCE and Siemens MRS processing software are also discussed in this paper.
  
  
  CONCLUSIONS
  The AQoCE approach is an automated method of residual water removal and metabolite quantification. It can be applied to multi-voxel 1H-MRS for evaluating brain glioma grading and demonstrating characteristics of brain glioma metabolism. It can also detect infiltration in the peritumoral area. Under the limited clinical data used, AQoCE is significantly more versatile and efficient compared to the reference approach of Siemens.
authors.affiliation: Department of Electronic Engineering, Tsinghua University, Beijing, China.
authors.forename: Weibei
authors.initials: W
authors.lastname: Dou
authors.affiliation: Radiology Department of Beijing Tian Tan Hospital, Capital Medical University, Beijing, China; Beijing Neurosurgical Institute, Beijing, China.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Electronic Engineering, Tsinghua University, Beijing, China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Electronic Engineering, Tsinghua University, Beijing, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Radiology Department of Beijing Tian Tan Hospital, Capital Medical University, Beijing, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Beijing Neurosurgical Institute, Beijing, China.
authors.forename: Shaowu
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Electronic Engineering, Tsinghua University, Beijing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Lu
authors.affiliation: Radiology Department of Beijing Tian Tan Hospital, Capital Medical University, Beijing, China; Beijing Neurosurgical Institute, Beijing, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Dai
authors.affiliation: Neuroradiology Service, University Hospital, Amiens, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Constans
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology; D001331:Automation; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002648:Child; D005260:Female; D005910:Glioma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D055815:Young Adult