Metabolic profile of PML lesions in patients with and without IRIS: an observational study.
OBJECTIVE
To characterize progressive multifocal leukoencephalopathy (PML) lesions by contrast-enhanced MRI and evaluate their metabolism using proton magnetic resonance spectroscopy ((1)H- MRS) in the setting of immune reconstitution inflammatory syndrome (IRIS).


METHODS
A total of 42 patients with PML underwent a clinical evaluation as well as brain MRI and (1)H-MRS at baseline and 3, 6, and 12 months later. The presence of IRIS was determined based on clinical and laboratory criteria. Ratios of N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and lipid/lactate (Lip1 and Lip2) to creatine (Cr) were measured and correlated with the presence of contrast enhancement (CE) in PML lesions.


RESULTS
IRIS occurred in 16 of 28 (57.1%) PML survivors (PML-S) and 1 of 14 (7.1%) PML progressors (PML-P). Lesions of patients with PML-IRIS showed significantly higher Cho/Cr (p = 0.0001), mI/Cr (p = 0.02), Lip1/Cr (p < 0.0001), and Lip2/Cr (p = 0.002) ratios and lower NAA/Cr (p = 0.02) ratios than patients with PML who did not have IRIS. An elevated Cho/Cr ratio was associated with CE within the (1)H-MRS voxel, whereas lipid/Cr ratios were elevated in PML-IRIS lesions independently of CE. Follow-up until 33 months from PML onset showed persistent elevation of the mI/Cr ratio in lesions of patients with PML-IRIS. A Lip1/Cr ratio greater than 1.5 combined with the presence of CE yielded a 79% probability of IRIS compared with 13% in the absence of these criteria.


CONCLUSIONS
(1)H-MRS is a valuable tool to recognize and track IRIS in PML and may prove useful in the clinical management of these patients.
Division of Neurovirology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA., USA.
Sarah
S
Gheuens
Long
L
Ngo
Xiaoen
X
Wang
David C
DC
Alsop
Robert E
RE
Lenkinski
Igor J
IJ
Koralnik
D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006679:HIV Seropositivity / Q000150:complications / Q000378:metabolism / Q000473:pathology; D006801:Humans; D054019:Immune Reconstitution Inflammatory Syndrome / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D007968:Leukoencephalopathy, Progressive Multifocal / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged