It's one thing for acute stroke imaging to predict final infarct volume or a patient's risk of 90-day mortality. It's quite another for imaging to predict whether a patient will recover upper extremity dexterity or language skills, or to what extent the patient will be able to function independently.
It's one thing for acute stroke imaging to predict final infarct volume or a patient's risk of 90-day mortality. It's quite another for imaging to predict whether a patient will recover upper extremity dexterity or language skills, or to what extent the patient will be able to function independently.
Researchers are only beginning to explore MRI's potential for making these types of functional outcome predictions, and although some studies have in fact found lesion volume on MRI to be predictive of function, these have been plagued by methodological flaws.1 In April 2006, an 82-patient study conducted by researchers from the University of Edinburgh concluded that imaging variables were not independent 3-month outcome predictors for a heterogeneous group of patients but suggested that MR diffusion-weighted imaging might have predictive value in patients with severe stroke.2
Because the National Institutes of Health Stroke Scale is such a strong predictor of outcome, any added value from imaging may be inconsequential in patients with less severe stroke, in whom small NIHSS changes have large effects on outcome. In those with more severe stroke, small NIHSS changes have less of an effect on outcome, opening the door for MRI's additional predictive information to carry more weight.
"It might be worth using MR lesion volume as a predictor in patients with severe strokes only, but not in all strokes," said Joanna M. Wardlaw, MD, a professor of neuroradiology at Edinburgh.
Increasingly, researchers are examining the predictive value of MRI in the shorter term, looking for associations between lesion volume and acute functional recovery. Investigators from Dusseldorf reported that MRI-based penumbral imaging was predictive of recovery of grip force and movement rate during repetitive finger-thumb pinching movements between day 1 and day 8 after acute hemiparetic stroke in 36 patients.3 Researchers from Johns Hopkins University found that a diffusion-clinical mismatch, which uses clinical language tests instead of imaging to approximate perfusion abnormality, was predictive of language improvement within 1 week in 81 patients with acute left hemispheric stroke.4
Still largely unknown is the extent to which individual impairments, such as lack of grip strength, translate to functional impairment in a patient population known for its ability to compensate both neurologically and functionally. Such compensation mechanisms may render imaging better able to predict impairment than function, but this too may vary depending on stroke severity or other factors.
"What matters to patients and healthcare providers in general is whether the patient can return to independent existence, and if not, then how much help do they need," Wardlaw said.
MRI-Based AI Radiomics Model Offers 'Robust' Prediction of Perineural Invasion in Prostate Cancer
July 26th 2024A model that combines MRI-based deep learning radiomics and clinical factors demonstrated an 84.8 percent ROC AUC and a 92.6 percent precision-recall AUC for predicting perineural invasion in prostate cancer cases.
Breast MRI Study Examines Common Factors with False Negatives and False Positives
July 24th 2024The absence of ipsilateral breast hypervascularity is three times more likely to be associated with false-negative findings on breast MRI and non-mass enhancement lesions have a 4.5-fold likelihood of being linked to false-positive results, according to new research.
Can Polyenergetic Reconstruction Help Resolve Streak Artifacts in Photon Counting CT?
July 22nd 2024New research looking at photon-counting computed tomography (PCCT) demonstrated significantly reduced variation and tracheal air density attenuation with polyenergetic reconstruction in contrast to monoenergetic reconstruction on chest CT.