title: Magnetic resonance elastography detects tumoral consistency in pituitary macroadenomas.
abstract: BACKGROUND
  Most pituitary macroadenomas (PMA) are soft and suckable allowing transsphenoidal resection. A small percentage of PMA are firm, which significantly alters the time, technical difficulty, and effectiveness of transsphenoidal surgery. No current imaging technology can reliably assess PMA viscoelastic consistency in preparation for surgery. Magnetic resonance elastography (MRE) is an MRI-based technique that measures the propagation of mechanically induced shear waves through tissue to calculate stiffness. We prospectively evaluated MRE in 10 patients undergoing transsphenoidal resection of PMA to determine feasibility and potential usefulness.
  
  
  METHODS
  10 patients with PMA > 2.0 cm in maximum diameter were prospectively imaged with MRE prior to transsphenoidal surgery. Mean patient age was 59.5 ± 16.2 (22-78) years. Five were female and five male. MRE was performed with a modified single-shot spin-echo echo-planar-imaging pulse sequence on a 3T MRI. MRE values were independently calculated. The surgeon, blinded to the MRE results, graded tumor consistency at surgery as soft, intermediate, or firm. Chi-squared test compared surgical grading and MRE stiffness values.
  
  
  RESULTS
  MRE was accomplished in all patients with excellent resolution. By surgical categorization, six tumors were soft and four intermediate. The mean MRE value for soft tumors was 1.38 ± 0.36 (1.08-1.87) kPa, while for intermediate tumors it was 1.94 ± 0.26 (1.72-2.32) kPa (p = 0.020).
  
  
  CONCLUSIONS
  Determination of PMA stiffness is feasible with MRE. There was a statistically significant difference in MRE values between soft and intermediate PMAs. Further study in a larger series is ongoing to determine whether MRE will prove useful in preoperative planning for PMA.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Hughes
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA.
authors.forename: Nikoo
authors.initials: N
authors.lastname: Fattahi
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, USA.
authors.forename: J
authors.initials: J
authors.lastname: Van Gompel
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA.
authors.forename: Arvin
authors.initials: A
authors.lastname: Arani
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Ehman
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA. jhuston@mayo.edu.|Mayo Clinic, 200 1st Street SW, Rochester, MN, 55901, USA. jhuston@mayo.edu.
authors.forename: John
authors.initials: J
authors.lastname: Huston
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000601:surgery; D000328:Adult; D000368:Aged; D054459:Elasticity Imaging Techniques; D005240:Feasibility Studies; D005260:Female; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007016:Hypophysectomy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D011446:Prospective Studies; D055815:Young Adult
keywords: Consistency; MRE; Magnetic resonance elastography; Pituitary macroadenoma; Stiffness