title: Diffusion-weighted MRI in 300 patients presenting late with subacute transient ischemic attack or minor stroke.
abstract: OBJECTIVE
  Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear history and clinical signs may have resolved. Because ischemic lesions on diffusion-weighted MRI (DWI) often persist for several weeks, we hypothesized that adding DWI to a standard protocol with T2-weighted imaging might be useful in the management of patients presenting late.
  
  
  METHODS
  We studied consecutive patients with TIA or minor stroke presenting > or =3 days after the event. Two independent observers recorded the presence or absence of recent ischemic lesions on 2 different occasions, first with the T2 scan only, and second with T2 and DWI. Each time, with the aid of a written clinical summary, the observers recorded their diagnosis and proposed management.
  
  
  RESULTS
  300 patients (159 men) were scanned at a median of 17 (interquartile range=10 to 23) days after symptom onset. DWI showed a high signal lesion in 114/164 (70%) minor strokes versus 17/136 (13%) TIAs (P<0.0001). The presence of high-signal lesions on DWI decreased nonlinearly with time since symptom onset (P<0.0001) and increased with National Institutes of Health Stroke Score (P=0.038) and with age (P=0.01). In 90/206 (43.7%) patients with 1 or multiple lesions on T2, DWI helped to clarify whether these were related to a recent ischemic event (79 [48%] strokes; 11 [31%] TIAs). Compared with T2 alone, DWI provided additional information in 108 (36%) patients (91 [56%] strokes and 17 [13%] TIAs), such as clarification of clinical diagnosis (18 patients, 6%) or vascular territory (28 patients, 9.3%), which was considered likely to influence management in 42 (14%) patients (32 [19%] strokes; 10 [7.4%] TIAs).
  
  
  CONCLUSIONS
  The clinically useful information available from DWI provides a further justification for an MRI-based imaging protocol in patients with subacute TIA or minor stroke.
authors.affiliation: Stroke Prevention Research Unit, Department of Clinical Neurology, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, UK.
authors.forename: Ursula G
authors.initials: UG
authors.lastname: Schulz
authors.forename: Dennis
authors.initials: D
authors.lastname: Briley
authors.forename: Tom
authors.initials: T
authors.lastname: Meagher
authors.forename: Andrew
authors.initials: A
authors.lastname: Molyneux
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rothwell
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D008297:Male; D011446:Prospective Studies; D020521:Stroke / Q000175:diagnosis*