Objectives:

1. This version includes the instructor answer key; these are slides labeled “ANSWERS”. MedNeuro Neuroimaging LabMary Kate Worden, Ph.D., Dept of Neuroscience and Myla Goldman, M.D., Dept of Neurology Objectives: • To review the planes of section and the appearance of the CNS and PNS in different imaging modalities. • To identify normal and abnormal structures in neuroimages. • To predict how neural lesions can give rise to symptoms in patients. Slide 1

2. Q1. Identify the imaging modality, orientation and plane of section for these images. Q2. One of these patients has motor weakness and the other has sensory deficits. Identify the abnormalities in these images and explain the symptoms. A. B. Slide 2

3. Superior Anterior Posterior A. B. T2 weighted sagittal MRI This patient has a syrinx extending from T1-T3. It appears as a white streak within the center of the spinal cord (white arrows). Note: the abnormal appearance of this patient’s back is a side effect of steroid treatment for another medical issue. ANSWER

4. B. Superior Posterior Anterior A. T2 weighted sagittal MRI This patient has bulging discs at levels C4-C5 (white arrows). These are compressing the ventral aspect of the spinal cord (corticospinal fibers), resulting in motor weakness at levels at and below the compression. Note also a white plaque within the spinal cord at C3 (black arrow). This patient also has MS. ANSWER

5. Q3.Identify the internal carotid angiogram and the vertebral artery angiogram. Q4. Identify PCA, ACA, vertebral arteries, internal carotid, superior cerebellar artery, cortical branches of MCA, PCA, lenticulostriate arteries, ophthalmic artery, basilar artery, posterior communicating artery, insular branches of MCA, and PICA. (Hint: at least one artery listed cannot be seen. Why not?) Slide 3

6. The ophthalmic artery cannot be seen in this internal carotid angiogram because it extends out of the plane of the image towards you. However, you might see it in a lateral view. ANSWER

7. The ophthalmic artery cannot be seen in this vertebral artery angiogram because it arises from the anterior (not the posterior) circulation. ANSWER

8. Case study Patient’s lower back A ten year old girl with a history of minimal health care presents with low back pain, increased lower extremity weakness, and incidence of bladder incontinence. Her neural shows decreased function in her dorsal and plantal flexors bilaterally, decreased function of the left quadraceps femoris musculature, decreased reflexes (pateller and ankle) and sensory deficit (decreased sensation to pin prick) of the left L5 dermatome. She also has focal hirsutism of the lower back (indicated by arrow on image). You send her to radiology (next slide). Slide 4

9. Patient Q5. Identify the imaging modality, the orientation and the plane of section. Q6. Identify the structure indicated by the arrows. Normal Slide 5

10. Q5. Both images on the previous slide are CT scans showing a transverse section through lumbar spinal cord. Both have identical orientation. Anterior/ventral Q6. The arrows indicate an abnormality: a boney process extending through the spinal column, dividing it into two hemicords. The patient underwent surgery to remove the bone. Right Left Posterior/dorsal ANSWER

11. Patient L5 Normal Q7. Identify the modality of imaging, the orientiation and the plane of section. What does the arrow point to in the image of the patient? Q8. Identify the level of the conus medullaris in the patient and in the normal image. At what level is a lumbar puncture performed? Slide 6

12. Patient L5 Normal Rostral/superior Posterior Anterior Caudal/inferior Q7. Both MRI images are longitudinal sections through lumbar spinal cord in the same orientation. The black arrow points to an abnormal boney process extending through the spinal cord of the patient from anterior to posterior. Q8. The conus medullaris (white arrow) is at level L3-L4 in the patient and at level L1-L2 in the normal image. Lumbar punctures are performed at L3. ANSWER

13. Neuroradiographs from this patient. Q9. What do you think caused the abnormalities you see in these images from this patient? Q10. Explain why the clinicians who treated this patient described her spinal cord as “tethered”. Q11. How do these images explain her symptoms? Slide 7

14. Neuroradiographs from this patient. Q9. Abnormalities in this patient are likely to be developmental defects, resulting from incomplete closure of the neural tube. Focal hirsutism on the back is sometimes the only external sign of spinal bifida. Q10. The patient’s spinal cord is “tethered” because the abnormal bony process fixes the spinal cord in place within the vertebral column. This can stretch the spinal roots as the patient grows. Q11. The patient’s symptoms are likely to be secondary to the stretching of the spinal roots. Her symptoms were relieved to a great extent by surgery that removed the boney process dividing her spinal cord. ANSWER

15. Q12. Identify the imaging modality and plane of section. Q13. Which image is superior to the other? Q14. Identify the lesion and the arterial territory in which it is located. Q15. Identify the cerebral peduncles, the third ventricle and the lateral fissure. Slide 8

16. Q12. MRI Axial section T-2 weighted (notice CSF is white in occipital horns) Q13. Image on left is dorsal/superior to image on right. Q14. The red circles arrow indicates the lesion. It is located in MCA territory. Q15. Cerebral peduncles are indicated by solid white arrows. Third ventricle is indicated by black arrows. Lateral fissure is indicated by yellow arrowheads. ANSWER

17. Q16. Which of the following functions do you suspect might be impaired in this patient? Explain. sensory (if so, where?) vestibular function motor function (if so, where?) language Slide 9

18. Q16. Which of the following functions do you suspect might be impaired in this patient? Explain. sensory: Yes, sensory function is likely to be impaired on right side of body. The lesion located in the region of primary somatosensory cortex vestibular function: No, vestibular nuclei and vestibular pathways are not at this level of the neuraxis motor function: Yes, motor function of the right side of the body is likely to be impaired because the lesion is located in the region of the primary motor cortex language: Yes, lesion is located in the perisylvian areas on the lateral aspect of the left hemisphere. ANSWER

19. Authors of a study of schizophrenic patients measured the “gyrification index” in each patient as the ratio of length of the inner cortical contour to the length of the outer cortical contour. Q17. What is the imaging modality and orientation? Q18. Which side of the brain did they measure in these images? Q19. Identify the internal capsule. What is the internal capsule composed of? Slide 10

20. Q17. What is the imaging modality and orientation? T-1 MRI, coronal sections Q18. Which side of the brain did they measure in these images? Left Q19. Identify the internal capsule. What is the internal capsule composed of? See red arrows. The internal capsule is composed of myelinated fibers carrying sensory information ascending to the brain and motor information descending from the brain. ANSWER

21. Authors of a study of schizophrenic patients measured the “gyrification index” in each patient as the ratio of length of the inner cortical contour to the length of the outer cortical contour. Q20. What lobe(s) of the brain are measured in the anterior segment image? In the posterior segment image? Q21. What would you estimate the “gyrification index” to be in these images? Slide 11

22. Authors of a study of schizophrenic patients measured the “gyrification index” in each patient as the ratio of length of the inner cortical contour to the length of the outer cortical contour. Q20. What lobe(s) of the brain are measured in the anterior segment image? frontal lobe In the posterior segment image? frontal and temporal lobes Q21. What would you estimate the “gyrification index” to be in these images? Actual values reported in the study were in the range 2.0 to 2.7 ANSWER

23. The authors of this study reported that schizophrenics have a lower gyrification index than normal patients. Sallet et al (2003) Am J Psychiatry 160:1606-1613, Reduced cortical folding in schizophrenics: An MRI morphometric study Q22. Do you think that the degree of structural abnormality might correlate with the degree of symptoms in these patients? Why or why not? Q23. What do you think caused the the structural abnormalities reported by these authors? Slide 12

24. The authors of this study reported that schizophrenics have a lower gyrification index than normal patients. Sallet et al (2003) Am J Psychiatry 160:1606-1613, Reduced cortical folding in schizophrenics: An MRI morphometric study Q22. Do you think that the degree of structural abnormality might correlate with the degree of symptoms in these patients? Why or why not? Brain dysfunction sometimes correlates with gross structural abnormalities but sometimes does not. The authors of this study reported structural abnormalites were found in the left (but not the right) hemispheres of disorganized schizophrenics. No abnormalities were found in other groups of schizophrenic patients (for example, paranoid schizophrenics had normal gyrification indices). In In other diseases such as Parkinson’s or Huntington’s or Alzheimers, gross abnormalities may appear in late stages of the disease but not in early stages. PET scans can sometimes reveal abnormalities of brain metabolism that are not obvious from structural studies conducted by CT or MRI imaging. Q23. What do you think caused the the structural abnormalities reported by these authors? Most likely: neurodevelopmental abnormalities. These might include errors in neuronal migration and/or formation of cortical lamina. ANSWER