title: Initial experience of 3 Tesla versus conventional field strength magnetic resonance imaging of small functioning pituitary tumours.
abstract: BACKGROUND
  Higher field strength magnetic resonance imaging (MRI) is becoming increasingly available and offers improved image quality; however, the clinical usefulness of this technique for the demonstration of surgically treatable functional pituitary adenomas has not been clearly established.
  
  
  OBJECTIVE
  To determine whether 3 Tesla (3T) MRI improves the detection of ACTH- and GH-secreting microadenomas over conventional imaging at field strengths of up to 1·5 Tesla (1·5T).
  
  
  METHODS
  Data sets from postgadolinium T1-weighted MRI at 1·5T and 3T were blinded, randomly ordered and assessed for the presence of pituitary tumour by two radiologists. Where possible, lesion signal difference to noise ratio (SDNR) was calculated for quantitative comparison. Imaging diagnoses were correlated with subsequent surgical and histological findings.
  
  
  METHODS
  Twenty-four patients (10 men, 14 women) with biochemical evidence of Cushing's disease (19) or acromegaly (5) were identified over a 5-year period.
  
  
  RESULTS
  1·5T MRI gave a clear diagnosis of 12 pituitary tumours, all confirmed at 3T. Four additional definite lesions and one suspicious case were correctly identified at 3T. Histological correlation in 21 cases showed sensitivity improving from 54% with 1·5T to 85% with 3T. Radiologists' subjective image preference favoured 3T in 92%. Quantitative difference between tumour and parenchymal signal was significantly greater at 3T (mean SDNR -7·9 [3T] and -2·8 [1·5T], paired t-test P < 0·05).
  
  
  CONCLUSIONS
  3T MRI appears to offer increased conspicuity and detection of GH- and ACTH-secreting pituitary microadenomas. It is potentially clinically useful when 1·5T imaging is negative or equivocal.
authors: Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK.
authors: David B
authors: DB
authors: Stobo
authors: Robert S
authors: RS
authors: Lindsay
authors: John M
authors: JM
authors: Connell
authors: Laurence
authors: L
authors: Dunn
authors: Kirsten P
authors: KP
authors: Forbes