Susceptibility-Weighted MR Imaging Hypointense Rim in Progressive Multifocal Leukoencephalopathy: The End Point of Neuroinflammation and a Potential Outcome Predictor

Abstract

BACKGROUND AND PURPOSE: Progressive multifocal leukoencephalopathy (PML) represents a life-threatening demyelinating disorder of the brain caused by reactivation of a rare opportunistic infection with JC Polyomavirus. The aims of this study were to describe the incidence of a susceptibility-weighted imaging hypointense rim in patients with multifocal leukoencephalopathy and to explore the histologic correlates and prognostic value of the rim with regard to the clinical outcome. MATERIALS AND METHODS: This retrospective study included 18 patients with a definite diagnosis of progressive multifocal leukoencephalopathy. Ten patients were HIV-positive, 3 patients had natalizumab-associated progressive multifocal leukoencephalopathy, 1 patient had multiple myeloma, 3 patients had a history of lymphoma, and 1 was diagnosed with acute myeloid leukemia. Patients were divided into short-(up to 12 months) and long-term (Ͼ12 months) survivors. A total of 93 initial and follow-up MR imaging examinations were reviewed. On SWI, the presence and development of a hypointense rim at the periphery of the progressive multifocal leukoencephalopathy lesions were noted. A postmortem histologic examination was performed in 2 patients: A rim formed in one, and in one, there was no rim. RESULTS: A total of 73 progressive multifocal leukoencephalopathy lesions were observed. In 13 (72.2%) patients, a well-defined thin, linear, hypointense rim at the periphery of the lesion toward the cortical side was present, while in 5 (27.8%) patients, it was completely absent. All 11 long-term survivors and 2 short-term survivors presented with a prominent SWI-hypointense rim, while 5/7 short-term survivors did not have this rim. CONCLUSIONS: The thin, uniformly linear, gyriform SWI-hypointense rim in the paralesional U-fibers in patients with definite progressive multifocal leukoencephalopathy might represent an end-point stage of the neuroinflammatory process in long-term survivors.

Progressive multifocal leukoencephalopathy: MRI findings in HIV-infected patients are closer to rituximab- than natalizumab-associated PML

“…The proportion of hyposignal seen on T2*-or SWANweighted images at the cortical-subcortical junction adjacent to PML lesions ( Fig. 6) did not differ between PML groups, in agreement with other studies [15,21,24]; this sign seems nonspecific in PML for the underlying cause of immunosuppression. A demyelination front on diffusion-weighted images is often found with PML in the HIV group and in the rituximab group but more rarely in the natalizumab group.…”

Neuroimaging Insights Into Early Stages of HIV-Progressive Multifocal Leukoencephalopathy: A Case Report

“…In PML, this neuroimaging feature has been proposed as a prognostic biomarker for long-term survival as it has postulated to be an end-point of the inflammatory process. 14 Interestingly, this rim has also been observed in chronic cerebral infarction and encephalitis. 20 The cause of this rim remains unresolved although it has been hypothesized to be secondary to iron deposition within macrophages.…”

“…Early stages of PML exhibit distinct neuroimaging features such as punctate pattern, increased signal in DWI along with T1-hypointensities, and involvement of the subcortical U-fibers. 2 , 12 - 14 Generally, these early structural changes are asymptomatic. Therefore, being able to recognize the early MRI findings associated with PML is of great importance to avoid misdiagnosis and facilitate the delivery of treatments aimed at reducing disease progression.…”

“… 20 The cause of this rim remains unresolved although it has been hypothesized to be secondary to iron deposition within macrophages. 14 Oligodendrocyte death due to JCV infection causes iron release which subsequently generates reactive oxygen species, ultimately leading to demyelination and cell death of the astrocytes and neurons. 21 …”

Opportunistische Infektionen des Nervensystems bei AIDS

“…Die Veränderungen sind v. a. im frontalen und parietookzipitalen Marklager lokalisiert und nehmen nur sehr selten schwach Kontrastmittel auf (in 5-10 %) [8,37]. Neuere Bildgebungstechniken ("b-Value"-diffusionsgewichtete Kernspintomografie; suszeptibilitätsartefaktgewichtete Sequenzen) eröffnen bessere diagnostische Möglichkeiten [38,39]. Der Liquor zeigt unspezifische HIV-assoziierte Veränderungen.…”