Infarcted brain regions with significant odds of developing HAP in stroke patients, expressed as log-OR (range −0.79 to 1.07; p<0.02).

<p>Displayed as axial and cortical 3-dimensional representations.</p

Voxel-wise odds for developing HAP when infarction present, expressed as log-OR (range −1.33 to 1.78; p<0.05).

<p>Voxel-wise odds for developing HAP when infarction present, expressed as log-OR (range −1.33 to 1.78; p<0.05).</p

Predominant infarct location in HAP patients and controls.

†<p>based on McNemar test.</p>*<p>supratentorial gray−/white matter excluding basal ganglia.</p

Univariate log-OR for supratentorial anatomic brain regions associated with HAP (as defined by p<0.05) and false discovery rate (q-value).

<p>L = left, R = right.</p

Prediction of poor outcome.

<p>Prediction of poor outcome.</p

Demographics, comorbidities, and treatment.

<p>Demographics, comorbidities, and treatment.</p

72-year-old female with altered mental status and ischemic stroke.

<p>On the 4-sequence MRI protocol (A-D), the axial FLAIR image (B) demonstrates multifocal ill-defined areas of signal hyperintensity within the midbrain with corresponding restricted diffusion on the axial diffusion weighted trace image (C), consistent with infarctions. Additional foci of infarction were seen in the left occipital lobe, left mesial temporal lobe, both thalami and the cerebellum (images not shown). No definite abnormality is seen on the sagittal T1-weighted image (A) or axial T2* image (D). MR angiography was also requested. MRA maximum intensity projection image (E) reveals thrombus with the distal basilar (white arrow) and proximal posterior cerebral arteries, which is confirmed on the axial source MR angiography images (F, G) (white arrow). Even in retrospect, this finding was not apparent on any of the sequences included in the 4-sequence MRI protocol. MRA imaging adds significant value in cases with clinical suspicion for vascular occlusion or thrombosis.</p

Patient Demographics and MRI Findings Group 2.

<p>Patient Demographics and MRI Findings Group 2.</p

22 year old female with right frontal hemispheric dysplasia.

<p>Sagittal T1-weighted image (A) shows no definite abnormality. Axial FLAIR image (B) demonstrates subtle enlargement of the right hemisphere with focal areas of signal hyperintensity within the subcortical white matter of the right frontal and parietal lobes but without corresponding restricted diffusion on the axial diffusion weighted trace (C) image. Additionally noted is ipsilateral ventricular enlargement. Pachygyria was also demonstrated within the right frontal and parietal lobes, better demonstrated on more superior axial FLAIR images. Axial T2-weighted image (D) also demonstrates these findings. Sagittal T1-weighted image (E) shows no definite abnormality. Axial FLAIR image (F) demonstrates asymmetric cortical thickening, gyral enlargement within the right frontal and parietal lobes without restricted diffusion on the axial diffusion weighted trace (G) image, consistent with pachygyria. Coronal FLAIR image (H) reveals asymmetric cortical thickening, abnormal sulcation and white matter signal hyperintensity in the right parietal lobe. The group 1 reader described the right frontal lobe signal abnormality, but did not diagnose the full extent of the hemispheric abnormality. These findings are more apparent on the coronal FLAIR sequence, not available to the reader.</p

Cortical dysplasia versus dysembryoplastic neuroepithelial tumor in an 18 year old male with seizures.

<p>Sagittal T1-weighted image (A) shows no definite abnormality. Axial T2-weighted FLAIR image (B) demonstrates a subtle focal area of signal hyperintensity within the cortex and subcortical white matter of the left parafalcine parietal lobe(white arrow) with no corresponding restricted diffusion on the axial diffusion weighted trace (C) image. Axial T2-weighted image (D) again demonstrates the hyperintense lesion within the cortex and subcortical white matter of the left parafalcine parietal lobe (white arrow), which is compatible with cortical dysplasia or dysembryoplastic neuroepithelial tumor. This finding is subtle and was not seen prospectively when using the limited sequences. However, the lesion can be seen on the FLAIR images in retrospect. Furthermore, for seizure patients, additional sequences, including isotropic multiplanar sequences, could be added that would help in identifying subtle abnormalities.</p