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Comparison of Perfusion, Diffusion, and MR Spectroscopy between Low-Grade Enhancing Pilocytic Astrocytomas and High-Grade Astrocytomas.
MedLine Citation:
PMID:  24699088     Owner:  NLM     Status:  Publisher    
BACKGROUND AND PURPOSE: The differentiation of pilocytic astrocytomas and high-grade astrocytomas is sometimes difficult. There are limited comparisons in the literature of the advanced MR imaging findings of pilocytic astrocytomas versus high-grade astrocytomas. The purpose of this study was to assess the MR imaging, PWI, DWI, and MR spectroscopy characteristics of pilocytic astrocytomas compared with high-grade astrocytomas.
MATERIALS AND METHODS: Sixteen patients with pilocytic astrocytomas and 22 patients with high-grade astrocytomas (8-66 years of age; mean, 36 ± 17 years) were evaluated by using a 1.5T MR imaging unit. MR imaging, PWI, DWI, and MR spectroscopy were used to determine the differences between pilocytic astrocytomas and high-grade astrocytomas. The sensitivity, specificity, and the area under the receiver operating characteristic curve of all analyzed parameters at respective cutoff values were determined.
RESULTS: The relative cerebral blood volume values were significantly lower in pilocytic astrocytomas compared with the high-grade astrocytomas (1.4 ± 0.9 versus 3.3 ± 1.4; P = .0008). The ADC values were significantly higher in pilocytic astrocytomas compared with high-grade astrocytomas (1.5 × 10(-3) ± 0.4 versus 1.2 × 10(-3) ± 0.3; P = .01). The lipid-lactate in tumor/creatine in tumor ratios were significantly lower in pilocytic astrocytomas compared with high-grade astrocytomas (8.3 ± 11.2 versus 43.3 ± 59.2; P = .03). The threshold values ≥1.33 for relative cerebral blood volume provide sensitivity, specificity, positive predictive values, and negative predictive values of 100%, 67%, 87%, and 100%, respectively, for differentiating high-grade astrocytomas from pilocytic astrocytomas. The optimal threshold values were ≤1.60 for ADC, ≥7.06 for lipid-lactate in tumor/creatine in tumor, and ≥2.11 for lipid-lactate in tumor/lipid-lactate in normal contralateral tissue.
CONCLUSIONS: Lower relative cerebral blood volume and higher ADC values favor a diagnosis of pilocytic astrocytoma, while higher lipid-lactate in tumor/creatine in tumor ratios plus necrosis favor a diagnosis of high-grade astrocytomas.
M de Fatima Vasco Aragao; M Law; D Batista de Almeida; G Fatterpekar; B Delman; A S Bader; M Pelaez; M Fowkes; R Vieira de Mello; M Moraes Valenca
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-4-3
Journal Detail:
Title:  AJNR. American journal of neuroradiology     Volume:  -     ISSN:  1936-959X     ISO Abbreviation:  AJNR Am J Neuroradiol     Publication Date:  2014 Apr 
Date Detail:
Created Date:  2014-4-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8003708     Medline TA:  AJNR Am J Neuroradiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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