MRI OF THE HEAD:
The MRI of the head shows diffuse atrophy. There is no abnormality of the craniocervical junction. There is a small probable mucus retention cyst in the inferior right maxillary sinus. The brainstem is grossly intact. There is a slight increase in atrophy with regards to the left temporal lobe in comparison to the right. This is mild asymmetry however. No large territorial defects are noted.
There is, however, noted on both the T2 and FLAIR images an area of very vague high signal along the left mid lateral ventricle region. This area of white matter suggests some probable demyelination. This is brought up in particular because, when contrast was given, there was a very vague sliver of enhancement directly in that area. This is seen on coronal imaging as well. This could be related to some collateral vessels and they are seen with contrast. Collateral vessels will be necessary due to the absence of good flow to the left MCA and ICA distribution on the left on the MRA, which will be described further following this report. Therefore, that is felt the most likely etiology. Other etiologies on this very vague and subtle enhancement would be tumor or luxury blood flow around a recent small ischemic insult. I would recommend that this simply be followed up over time in approximately 6 to 9 months or sooner if symptoms change.
There is no other area of enhancement of concern that is noted. We do see some asymmetry to the vascular venous drainage pattern with the gadolinium on the axial images in the posterior fossa and around the temporal lobe region on the left, which most likely again is related to the change in collateral flow to the left cerebral hemisphere.
The IAC and cerebellopontine angle regions do not show masses. No enhancing abnormality is noted to suggest an acoustic tumor. The inner ear and mastoid air cells are well aerated.
IMPRESSION:
1. Diffuse atrophy.
2. FLAIR and T2 weighted images suggests some ischemic high signal changes in the white matter adjacent to the left lateral ventricle. In this area, with gadolinium, a small sliver of enhancement persists on both axial and coronal images. This sliver of enhancement may be related to collateral blood flow or luxury perfusion or recent ischemic insult. It could, though felt less likely, be related to mild enhancement of an underlying tumor. I feel this is less likely, and in light of no change in clinical symptoms, I would recommend simply a repeat MRI with gadolinium in approximately 6 to 9 months.
3. No other abnormal enhancement is noted.
4. There is a mild increase in atrophy with regards to the left temporal lobe when compared to the right; however, this is diffuse and subtle.
5. The internal auditory canal and cerebellopontine angle regions are normal in appearance.
MRA OF CIRCLE OF WILLIS:
The circle of Willis shows absence of normal flow to the left internal carotid artery. There is no vertebral or petrous portion identified on this examination. No supraclinoid portion is noted and no normal left middle cerebral artery is present. We do have both a left and right anterior cerebral artery, which appears to be fed predominantly from the right side.
We see a very small amount of flow in an area, which may be a remnant or collateralized left MCA. MRA tends to overemphasize areas of narrowing such that there may be a small residual left middle cerebral artery with reduced flow. There is some flow that is seen distally in the left middle cerebral artery distribution, which is presumably due to some collateralization.
The right middle cerebral artery is patent without significant focal narrowing. There is some mild atherosclerotic disease noted in the internal carotid artery as well as the mid and distal right middle cerebral artery. The right A1 segment is pronounced and appears to predominantly feed both the anterior cerebral arteries.
There is no visible posterior communicating artery on this examination. The basilar artery is grossly intact with some mild atherosclerotic disease. No varying aneurysm is noted. Bifurcation to the right and left posterior cerebral arteries is symmetrical with some mild atherosclerotic disease suggested in both of those arteries.
IMPRESSION:
1. Absence of a left internal carotid artery or a normal left middle cerebral artery on this examination. There is some very minimal horizontal flow where one would expect the left middle cerebral artery such that there may be some residual small flow, which is not as easily detected on MRA. Also, there are some distal branches in the area of the temporal artery region of the distal left middle cerebral artery distribution; this may be fed by collateral flow.
2. There is no apparent posterior communicating artery to lend definite connection between the posterior and anterior circulations.
3. Both the left and right anterior cerebral arteries are noted and fed predominantly by the right A1 segment.
4. Some mild atherosclerotic disease is noted in the right internal carotid artery and some mild atherosclerotic disease is present in the distal right middle cerebral artery.
