Korean J Radiol.  2011 Aug;12(4):463-472. 10.3348/kjr.2011.12.4.463.

Assessment of Cortical Visual Impairment in Infants with Periventricular Leukomalacia: a Pilot Event-Related fMRI Study

• Yu B
• Guo Q
• Fan G
• Liu N

• KMID: 1783213
• DOI: http://doi.org/10.3348/kjr.2011.12.4.463

Abstract

OBJECTIVE
We wanted to investigate the usefulness of event-related (ER) functional MRI (fMRI) for the assessment of cortical visual impairment in infants with periventricular leukomalacia (PVL).
MATERIALS AND METHODS
FMRI data were collected from 24 infants who suffered from PVL and from 12 age-matched normal controls. Slow ER fMRI was performed using a 3.0T MR scanner while visual stimuli were being presented. Data analysis was performed using Statistical Parametric Mapping software (SPM2), the SPM toolbox MarsBar was used to analyze the region of interest data, and the time to peak (TTP) of hemodynamic response functions (HRFs) was estimated for the surviving voxels. The number of activated voxels and the TTP values of HRFs were compared. Pearson correlation analysis was performed to compare visual impairment evaluated by using Teller Acuity Cards (TAC) with the number of activated voxels in the occipital lobes in all patients.
RESULTS
In all 12 control infants, the blood oxygenation level-dependent (BOLD) signal was negative and the maximum response was located in the anterior and superior part of the calcarine fissure, and this might correspond to the anterior region of the primary visual cortex (PVC). In contrast, for the 24 cases of PVL, there were no activated pixels in the PVC in four subjects, small and weak activations in six subjects, deviated activations in seven subjects and both small and deviated activations in three subjects. The number of active voxels in the occipital lobe was significantly correlated with the TAC-evaluated visual impairment (p < 0.001). The mean TTP of the HRFs was significantly delayed in the cases of PVL as compared with that of the normal controls.
CONCLUSION
Determining the characteristics of both the BOLD response and the ER fMRI activation may play an important role in the cortical visual assessment of infants with PVL.

Keyword

Periventricular leukomalacia; Magnetic resonance imaging, functional

MeSH Terms

Case-Control Studies
Evoked Potentials, Visual
Female
Humans
Image Interpretation, Computer-Assisted
Infant
Infant, Newborn
Leukomalacia, Periventricular/*physiopathology
Magnetic Resonance Imaging/*methods
Male
Photic Stimulation
Pilot Projects
Visual Acuity
Visual Cortex/*physiopathology

Figure

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  Fig. 1 Active area and hemodynamic response function of normal infant. Hemodynamic response function is located in upper right hand corner of active map.

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  Fig. 2 Active area and hemodynamic response function of full-term primary visual cortex infant. Active area is slightly decreased, time to peak is slightly prolonged and result of Teller Acuity Card examination is rated "+-".

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  Fig. 3 Active area and hemodynamic response function of full-term periventricular leukomalacia infant. Active area is deviated in nature, time to peak is prolonged and result of Teller Acuity Card examination is rated "+-".

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  Fig. 4 Active area and hemodynamic response function of pre-term periventricular leukomalacia infant. Active area is tiny and deviated, time to peak is slightly prolonged and result of Teller Acuity Card examination is rated "+".

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  Fig. 5 Active area and hemodynamic response function of pre-term periventricular leukomalacia infant. Active area is tiny, time to peak is obviously prolonged and result of Teller Acuity Card examination is rated "++".

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  Fig. 6 Scattergraph comparing visual impairment and fMRI data in periventricular leukomalacia (PVL) infants. Scattergraph shows relationship between visual impairment and number of active voxels in occipital lobe of periventricular leukomalacia infants.

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