This document discusses changes in the central nervous system that are commonly seen in patients with acquired immunodeficiency syndrome (AIDS). It provides 10 figures showing examples of various conditions on CT and MR imaging. Some of the conditions shown include toxoplasmosis, cryptococcosis, streptococcal abscess, lymphoma, progressive multifocal leukoencephalopathy, HIV encephalitis, and cytomegalovirus ventriculitis. The images demonstrate abnormalities such as enhancing lesions, masses, edema, and areas of abnormal signal that are characteristic of these opportunistic infections and tumors seen in AIDS patients.

1. 27Central Nervous System
Changes in Acquired
Immunodeficiency Syndrome

2. CLINICAL IMAGAGING
AN ATLAS OF DIFFERENTIAL DAIGNOSIS
EISENBERG
DR. Muhammad Bin Zulfiqar
PGR-FCPS III SIMS/SHL

3. • Fig SK 27-1 Toxoplasmosis. Contrast-enhanced CT scan
shows multiple small areas of ring and solid
enhancement in the region of the cerebral peduncles
and pons. A small round area of enhancement is seen
in the left occipital lobe.44

4. • Fig SK 27-2 Toxoplasmosis. Postcontrast T1-
weighted MR image shows at least three
enhancing lesions.6

5. • Fig SK 27-3 Cryptococcosis. Axial T2-weighted
MR scan shows a relatively isointense
peripheral mass (black arrowhead) with
prominent surrounding edema (white arrows).

6. • Fig SK 27-4 Cryptococcal meningitis. Contrast-enhanced CT scan
demonstrates dense enhancement of the free edge of the tentorium and
prominent enhancement of meninges in the right temporal and both
occipital regions. Scattered focal intracerebral areas of enhancement
(arrows) were thought to be caused by cryptococcal granulomas.44

7. • Fig SK 27-5 Streptococcal abscess. T2-weighted
MR scan shows a well-defined, slightly lobulated
mass in the left cerebellum. The margin of the
abscess has a rim of decreased signal intensity,
and there is moderate surrounding edema.44

8. • Fig SK 27-6 Lymphoma. Contrast-enhanced CT
scan shows large, bilateral areas of enhance
ment with surrounding edema in the basal
ganglia bilaterally. Another lesion is seen in
the left occipital pole (arrow).44

9. • Fig SK 27-7 Progressive multifocal
leukoencephalopathy. (A) Initial T2-weighted MR scan
shows irregularly marginated areas of increased signal
intensity in the region of the centrum semiovale
bilaterally. There is no mass effect, but severe atrophy
is seen. (B) Repeat study 3 months later shows
progression of the white matter abnormalities,
especially in the occipital region.45

10. • Fig SK 27-8 HIV encephalitis. Axial proton-density MR
image shows symmetric regions of abnormally
increased signal intensity without mass effect in the
centrum semiovale bilaterally (arrows).45

11. • Fig SK 27-9 Cytomegalovirus ventriculitis. (A)
Nonenhanced CT scan and (B) T1-weighted MR
scan show bilateral periventricular areas of
decreased attenuation/signal intensity, which is
most marked near the right frontal horn. Note
additional bilateral lesions in the basal ganglia.45

12. • Fig SK 27-10 Cytomegalovirus. (A) Axial T1-weighted
MR image demonstrates an irregular low-signal halo
(arrows) surrounding the right occipital horn. There is
no evidence of mass effect. (B) Axial proton-density
image shows corresponding high signal in the right
periatrial white matter (straight arrow). There are
similar high-signal foci in the periventricular white
matter adjacent to the right frontal horn (curved
arrow) and the medial left atrium (open arrow).46