title: Technical innovation in dynamic contrast-enhanced magnetic resonance imaging of musculoskeletal tumors: an MR angiographic sequence using a sparse k-space sampling strategy.
abstract: OBJECTIVE
  We demonstrate the clinical use of an MR angiography sequence performed with sparse k-space sampling (MRA), as a method for dynamic contrast-enhanced (DCE)-MRI, and apply it to the assessment of sarcomas for treatment response.
  
  
  METHODS
  Three subjects with sarcomas (2 with osteosarcoma, 1 with high-grade soft tissue sarcomas) underwent MRI after neoadjuvant therapy/prior to surgery, with conventional MRI (T1-weighted, fluid-sensitive, static post-contrast T1-weighted sequences) and DCE-MRI (MRA, time resolution = 7-10 s, TR/TE 2.4/0.9 ms, FOV 40 cm(2)). Images were reviewed by two observers in consensus who recorded image quality (1 = diagnostic, no significant artifacts, 2 = diagnostic, <25 % artifacts, 3 = nondiagnostic) and contrast enhancement characteristics by static MRI (presence/absence of contrast enhancement, percentage of enhancement) and DCE-MRI (presence/absence of arterial enhancement with time-intensity curves). Results were compared with histological response (defined as <5 % viable tumor [soft tissue sarcoma] or <10 % [bone sarcoma] following resection).
  
  
  RESULTS
  Diagnostic quality for all conventional and DCE-MRI sequences was rated as 1. In 2 of the 3 sarcomas, there was good histological response (≤5 % viable tumor); in 1 there was poor response (50 % viable tumor). By static post-contrast T1-weighted sequences, there was enhancement in all sarcomas, regardless of response (up to >75 % with good response, >75 % with poor response). DCE-MRI findings were concordant with histological response (arterial enhancement with poor response, no arterial enhancement with good response).
  
  
  CONCLUSIONS
  Unlike conventional DCE-MRI sequences, an MRA sequence with sparse k-space sampling is easily integrated into a routine musculoskeletal tumor MRI protocol, with high diagnostic quality. In this preliminary work, tumor enhancement characteristics by DCE-MRI were used to assess treatment response.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, 601 North Wolfe Street, Baltimore, MD 21287, USA. lfayad1@jhmi.edu
authors.forename: Laura M
authors.initials: LM
authors.lastname: Fayad
authors.forename: Charles
authors.initials: C
authors.lastname: Mugera
authors.forename: Theodoros
authors.initials: T
authors.lastname: Soldatos
authors.forename: Aaron
authors.initials: A
authors.lastname: Flammang
authors.forename: Filippo
authors.initials: F
authors.lastname: del Grande
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001859:Bone Neoplasms / Q000098:blood supply / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000098:blood supply / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000473:pathology*; D015203:Reproducibility of Results; D018401:Sample Size; D012509:Sarcoma / Q000098:blood supply / Q000473:pathology*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media
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