Low signal intensity in U-fiber identified by susceptibility-weighted imaging in two cases of progressive multifocal leukoencephalopathy

Diagnosing progressive multifocal leukoencephalopathy: Positive predictive value of CSF JC virus quantitative PCR and importance of recognizing suggestive neuroimaging findings

OBJECTIVE

To determine the positive predictive value (PPV) of CSF John Cunningham virus (JCV) quantitative PCR (qPCR) for progressive multifocal leukoencephalopathy (PML), and highlight neuroimaging findings reported to be suggestive of this disease.

METHODS

We reviewed patients at London Health Sciences Centre with a positive CSF JCV qPCR result. Patients were classified as true-positive if they had a clinico-radiographic presentation compatible with PML and no more likely alternative diagnosis. The presence of suggestive neuroimaging findings was documented as supportive evidence of PML. The PPV of CSF JCV qPCR was calculated as the proportion of positive results that were classified as true-positives.

RESULTS

Eleven of 154 patients who underwent CSF JCV qPCR testing had a positive result (7 %). Median age was 60 years (range: 33-79 years) and 7/11 (64 %) were male. Nine of 11 (82 %) were overtly immunocompromised. Five of 11 (45 %) had a viral load below the lowest quantifiable standard (<4290 copies/ml). All had a clinico-radiographic presentation compatible with PML and no more likely alternative diagnosis, resulting in a PPV of 100 %. All had one or more suggestive neuroimaging findings that supported PML diagnosis (Milky Way sign/punctate pattern, 9; rim-and-core pattern, 7; T2/FLAIR mismatch, 6; shrimp sign, 4; SWI-hypointense rim, 2; across-the-pons sign, 1; barbell sign, 1).

CONCLUSIONS

We found that CSF JCV qPCR had high PPV for PML. All positives below the lowest quantifiable standard were true-positives. Our study affirms the diagnostic utility of this testing in clinical practice. Recognition of suggestive neuroimaging findings helps facilitate PML diagnosis.

Progressive multifocal leukoencephalopathy associated with systemic lupus erythematosus: longitudinal observation of lymphocytes, JC virus in cerebrospinal fluid, and brain magnetic resonance imaging

Progressive multifocal leukoencephalopathy (PML) rarely occurs in patients with systemic lupus erythematosus (SLE). This report presents the case of a patient who developed PML due to SLE-associated multiple factors. A 60-year-old woman diagnosed with SLE undergoing multiple immunosuppressive therapies, including azathioprine, presented with cerebral cortical symptoms, lymphocytopenia, and vitamin B12 deficiency and was subsequently diagnosed with SLE-associated PML. We evaluated the cause and disease activity of PML, focusing on the longitudinal assessment of lymphocytopenia, JC virus (JCV) DNA copy number in the cerebrospinal fluid, and magnetic resonance imaging (MRI) findings. Discontinuing azathioprine and initiating alternative immunosuppressive treatments with intramuscular vitamin B12 injections affected lymphocytopenia and disease management. However, despite recovery from lymphopenia and JCV DNA copy number being low, the large hyperintense and punctate lesions observed on the fluid-attenuated inversion recovery (FLAIR) images exhibited varying behaviors, indicating that the balance between contributing factors for PML may have fluctuated after the initial treatment. Clinicians should be meticulous when assessing the underlying pathology of the multifactorial causes of PML due to SLE. The difference in the transition pattern of these lesions on FLAIR images may be one of the characteristics of MRI findings in PML associated with SLE, reflecting fluctuations in disease activity and the progression stage of PML.

Distinct subdivisions of subcortical U-fiber regions in the gyrencephalic ferret brain

The human cerebrum contains a large amount of cortico-cortical association fibers. Among them, U-fibers are short-range association fibers located in white matter immediately deep to gray matter. Although U-fibers are thought to be crucial for higher cognitive functions, the organization within U-fiber regions are still unclear. Here we investigated the properties of U-fiber regions in the ferret cerebrum using neurochemical, neuronal tracing, immunohistochemical and electron microscopic techniques. We found that U-fiber regions can be subdivided into two regions, which we named outer and inner U-fiber regions. We further uncovered that outer U-fiber regions have smaller-diameter axons with thinner myelin compared with inner U-fiber regions. These findings may indicate functional complexity within U-fiber regions in the cerebrum.

An autopsy case of progressive multifocal leukoencephalopathy with massive iron deposition in juxtacortical lesions

Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease caused by JC virus infection of oligodendrocytes. Little has been reported on iron deposits in patients with PML. Herein, we report a case of PML with massive iron deposition in the juxtacortical regions attaching white matter lesions in a 71-year-old woman who developed bilateral visual disturbance and progressive aphasia after 16 months of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone treatment for follicular lymphoma. Magnetic resonance imaging revealed white matter lesions in the left parietal and other lobes with massive iron deposition in the juxtacortical lesions. A PCR test for JC virus was positive, confirming the diagnosis of PML. Despite treatment with mefloquine and mirtazapine, the patient died six months later. At autopsy, demyelination was found dominantly in the left parietal lobe. Moreover, hemosiderin-laden macrophages and reactive astrocytes containing ferritin were abundant in the juxtacortical regions adjacent to the white matter lesions. This is a previously unreported case of PML after lymphoma, in which iron deposition was confirmed both radiologically and pathologically.

Secondary Central Nervous System Demyelinating Disorders in the Elderly: A Narrative Review

Secondary demyelinating diseases comprise a wide spectrum group of pathological conditions and may either be attributed to a disorder primarily affecting the neurons or axons, followed by demyelination, or to an underlying condition leading to secondary damage of the myelin sheath. In the elderly, primary demyelinating diseases of the central nervous system (CNS), such as multiple sclerosis, are relatively uncommon. However, secondary causes of CNS demyelination may often occur and in this case, extensive diagnostic workup is usually needed. Infectious, postinfectious, or postvaccinal demyelination may be observed, attributed to age-related alterations of the immune system in this population. Osmotic disturbances and nutritional deficiencies, more commonly observed in the elderly, may lead to conditions such as pontine/extrapontine myelinolysis, Wernicke encephalopathy, and demyelination of the posterior columns of the spinal cord. The prevalence of malignancies is higher in the elderly, sometimes leading to radiation-induced, immunotherapy-related, or paraneoplastic CNS demyelination. This review intends to aid clinical neurologists in broadening their diagnostic approach to secondary CNS demyelinating diseases in the elderly. Common clinical conditions leading to secondary demyelination and their clinical manifestations are summarized here, while the current knowledge of the underlying pathophysiological mechanisms is additionally presented.

Juxtacortical susceptibility changes in progressive multifocal leukoencephalopathy at the gray-white matter junction correlates with iron-enriched macrophages

OBJECTIVE

Describe magnetic resonance imaging (MRI) susceptibility changes in progressive multifocal leukoencephalopathy (PML) and identify neuropathological correlates.

METHODS

PML cases and matched controls with primary central nervous system lymphoma (PCNSL) were retrospectively identified. MRI brain at 3 T and 7 T were reviewed. MRI-pathology correlations in fixed brain autopsy tissue were conducted in three subjects with confirmed PML.

RESULTS

With PML (n = 26 total, n = 5 multiple sclerosis natalizumab-associated), juxtacortical changes on susceptibility-weighted imaging (SWI) or gradient echo (GRE) sequences were noted in 3/3 cases on 7 T MRI and 14/22 cases (63.6%) on 1.5 T or 8/22 (36.4%) 3 T MRI. Similar findings were only noted in 3/25 (12.0%) of PCNSL patients (odds ratio (OR) 12.83, 95% confidence interval (CI), 2.9-56.7, p < 0.001) on 1.5 or 3 T MRI. On susceptibility sequences available prior to diagnosis of PML, 7 (87.5%) had changes present on average 2.7 ± 1.8 months (mean ± SD) prior to diagnosis. Postmortem 7 T MRI showed SWI changes corresponded to areas of increased iron density along the gray-white matter (GM-WM) junction predominantly in macrophages.

CONCLUSION

Susceptibility changes in PML along the GM-WM junction can precede noticeable fluid-attenuated inversion recovery (FLAIR) changes and correlates with iron accumulation in macrophages.

Progressive multifocal leukoencephalopathy and the spectrum of JC virus-related disease

Progressive multifocal leukoencephalopathy (PML) is a devastating CNS infection caused by JC virus (JCV), a polyomavirus that commonly establishes persistent, asymptomatic infection in the general population. Emerging evidence that PML can be ameliorated with novel immunotherapeutic approaches calls for reassessment of PML pathophysiology and clinical course. PML results from JCV reactivation in the setting of impaired cellular immunity, and no antiviral therapies are available, so survival depends on reversal of the underlying immunosuppression. Antiretroviral therapies greatly reduce the risk of HIV-related PML, but many modern treatments for cancers, organ transplantation and chronic inflammatory disease cause immunosuppression that can be difficult to reverse. These treatments — most notably natalizumab for multiple sclerosis — have led to a surge of iatrogenic PML. The spectrum of presentations of JCV-related disease has evolved over time and may challenge current diagnostic criteria. Immunotherapeutic interventions, such as use of checkpoint inhibitors and adoptive T cell transfer, have shown promise but caution is needed in the management of immune reconstitution inflammatory syndrome, an exuberant immune response that can contribute to morbidity and death. Many people who survive PML are left with neurological sequelae and some with persistent, low-level viral replication in the CNS. As the number of people who survive PML increases, this lack of viral clearance could create challenges in the subsequent management of some underlying diseases.

In this Review, Cortese et al. provide an overview of the pathobiology and evolving presentations of progressive multifocal leukoencephalopathy and other diseases caused by JC virus, and discuss emerging immunotherapeutic approaches that could increase survival.

Progressive multifocal leukoencephalopathy (PML) is a rare, debilitating and often fatal disease of the CNS caused by JC virus (JCV).

JCV establishes asymptomatic, lifelong persistent or latent infection in immune competent hosts, but impairment of cellular immunity can lead to reactivation of JCV and PML.

PML most commonly occurs in patients with HIV infection or lymphoproliferative disease and in patients who are receiving natalizumab for treatment of multiple sclerosis.

The clinical phenotype of PML varies and is shaped primarily by the host immune response; changes in the treatment of underlying diseases associated with PML have changed phenotypes over time.

Other clinical manifestations of JCV infection have been described, including granule cell neuronopathy.

Survival of PML depends on reversal of the underlying immunosuppression; emerging immunotherapeutic strategies include use of checkpoint inhibitors and adoptive T cell transfer.

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

Objectives

To compare brain MRI findings in progressive multifocal leukoencephalopathy (PML) associated to rituximab and natalizumab treatments and HIV infection.

Materials and methods

In this retrospective, multicentric study, we analyzed brain MRI exams from 72 patients diagnosed with definite PML: 32 after natalizumab treatment, 20 after rituximab treatment, and 20 HIV patients. We compared T2- or FLAIR-weighted images, diffusion-weighted images, T2*-weighted images, and contrast enhancement features, as well as lesion distribution, especially gray matter involvement.

Results

The three PML entities affect U-fibers associated with low signal intensities on T2*-weighted sequences. Natalizumab-associated PML showed a punctuate microcystic appearance in or in the vicinity of the main PML lesions, a potential involvement of the cortex, and contrast enhancement. HIV and rituximab-associated PML showed only mild contrast enhancement, punctuate appearance, and cortical involvement. The CD4/CD8 ratio showed a trend to be higher in the natalizumab group, possibly mirroring a more efficient immune response.

Conclusion

Imaging features of rituximab-associated PML are different from those of natalizumab-associated PML and are closer to those observed in HIV-associated PML.

Key Points

• Nowadays, PML is emerging as a complication of new effective therapies based on monoclonal antibodies.

• Natalizumab-associated PML shows more inflammatory signs, a perivascular distribution “the milky way,” and more cortex involvement than rituximab- and HIV-associated PML.

• MRI differences are probably related to higher levels of immunosuppression in HIV patients and those under rituximab therapy.

Pomalidomide-associated progressive multifocal leukoencephalopathy in multiple myeloma: cortical susceptibility-weighted imaging hypointense findings prior to clinical deterioration

Although there are several case reports of progressive multifocal leukoencephalopathy (PML) in multiple myeloma (MM), there are few reports of cases associated with pomalidomide. Here, we report the case of a 69-year-old female who had received 41 cycles of pomalidomide and dexamethasone treatment for relapsed/refractory IgG-κ MM presented with right-hand weakness; she was diagnosed as pomalidomide-associated PML. Fluid-attenuated inversion recovery (FLAIR) on admission showed high signals in the bilateral front-parietal lobe white matter, with multiple punctate lesions in the vicinity of the main lesions. These punctate pattern findings on FLAIR were similar to that of natalizumab-associated PML. Susceptibility weighted imaging (SWI) showed hypointense rims within the cortex at unaffected sites, in the initial stages. Subsequently, the clinical manifestations deteriorated, and the FLAIR images showed new hyperintense white matter lesions at the sites where cortical SWI hypointense rims were detected on the initial MRI examination. Our patient's serial MRI findings suggest that cortical SWI hypointense rims appear prior to the visible demyelinating white matter lesions in patients with PML.

The origin and development of subcortical U-fibers in gyrencephalic ferrets

In the white matter of the human cerebrum, the majority of cortico-cortical fibers are of short range, connecting neighboring cortical areas. U-fibers represent connections between neighboring areas and are located in the white matter immediately deep to the cerebral cortex. Using gyrencephalic carnivore ferrets, here we investigated the neurochemical, anatomical and developmental features of U-fibers. We demonstrate that U-fibers were derived from neighboring cortical areas in ferrets. U-fiber regions in ferrets were intensely stained with Gallyas myelin staining and Turnbull blue iron staining. We further found that U-fibers were derived from neurons in both upper and lower layers in neighboring areas of the cerebral cortex and that U-fibers were formed later than axons in the deep white matter during development. Our findings shed light on the fundamental features of U-fibers in the gyrencephalic cerebral cortex. Because genetic manipulation techniques for ferrets are now available, ferrets should be an important option for investigating the development, functions and pathophysiological changes of U-fibers.

Cortical hypointensity in T2-weighted gradient-echo sequences in patients with progressive multifocal leukoencephalopathy

INTRODUCTION

Progressive multifocal leukoencephalopathy is a demyelinating disease of the central nervous system caused by the reactivation of the JC virus. This opportunistic encephalopathy mainly affects immunodepressed patients with stage III HIV infection, although in recent years it has also been found in association with treatment with immunosuppressors such as natalizumab. MRI plays an important role in both the early diagnosis and follow-up of this disease. Recently, it has been reported that hypointensities in U-fibers and cortex adjacent to white-matter lesions characteristic of the disease can be identified on T2-weighted gradient-echo and susceptibility-weighted sequences in patients with progressive multifocal leukoencephalopathy.

OBJECTIVE

We aimed to analyze the presence and usefulness of cortical hypointensity on T2-weighted gradient-echo sequences in relation to the diagnosis of progressive multifocal leukoencephalopathy and to review the literature on the topic.

MATERIAL AND METHODS

We analyze three cases of progressive multifocal leukoencephalopathy seen at our center in three patients with immunosuppression of different origins: one with stage III HIV infection, one with multiple sclerosis being treated with natalizumab, and one with rheumatoid arthritis being treated with rituximab.

RESULTS

In all three cases MRI showed the cortical hypointensity adjacent to the white-matter lesion in the T2-weighted gradient-echo sequence. In the patient with multiple sclerosis, this sign appeared earlier than the abnormal signal in the white matter. The patient being treated with rituximab was diagnosed postmortem and the pathology findings correlated with the MRI findings.

CONCLUSION

The finding of cortical hypointensity on T2-weighted gradient-echo MRI sequences seems to support the diagnosis of progressive multifocal leukoencephalopathy, regardless of the type of immunosuppression, so this finding should routinely assessed in patients suspected of having this disease.

Neurologic Complications of Human Immunodeficiency Virus Infection

PURPOSE OF REVIEW

Widespread use of antiretroviral therapy (ART) has led to near-normal life expectancy in people with human immunodeficiency virus (HIV) infection. However, neurologic complications of HIV remain common; can affect any part of the neuraxis; and are due to direct effects of the virus, immunosuppression because of untreated HIV infection, aberrant immune responses in the setting of ART initiation, and ART toxicities.

RECENT FINDINGS

HIV-associated neurocognitive disorder (HAND) remains one of the most common neurologic complications of HIV encountered today, but milder forms predominate in people on ART. No specific treatments for HAND exist, but small trials and epidemiologic evidence suggest paroxetine, intranasal insulin, and maraviroc may have utility in its treatment; further trials of these agents are ongoing. Widespread ART use has decreased the incidence of central nervous system opportunistic infections, but prognosis often remains poor in those who develop opportunistic infections. High-titer positive serum cryptococcal antigen is strongly predictive of cryptococcal meningitis and provides a tool to enhance diagnosis in areas with limited resources. HIV is an independent risk factor for stroke, and accelerated aging associated with HIV infection results in neurologic diseases of older age occurring at much younger ages in individuals infected with HIV. Ongoing HIV replication in the CSF despite peripheral virologic suppression may contribute to the development of HAND and may not improve despite adjusting the ART regimen to increase central nervous system penetrance.

SUMMARY

Neurologists are likely to encounter patients infected with HIV in clinical practice. This article reviews the presentation, diagnosis, and management of the most common neurologic conditions associated with HIV infection and ART.

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

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 (>12 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.

Diagnosis and Treatment of Progressive Multifocal Leukoencephalopathy Associated with Multiple Sclerosis Therapies

Progressive multifocal leukoencephalopathy (PML) is a rare, but serious, complication encountered in patients treated with a select number of disease-modifying therapies (DMTs) utilized in treating multiple sclerosis (MS). PML results from a viral infection in the brain for which the only demonstrated effective therapy is restoring the perturbed immune system-typically achieved in the patient with MS by removing the offending therapeutic agent or, in the case of HIV-associated PML, treatment with highly active antiretroviral therapies. Other therapies for PML remain either ineffective or experimental. Significant work to understand the virus and host interaction has been undertaken, but lack of an animal model for the disorder has significantly hindered progress, especially with respect to development of treatments. Strategies to limit risk of PML with natalizumab, a drug that carries a uniquely high risk for the development of the disorder, have been developed. Identifying factors such as positive JC virus antibody status that increase PML risk, at least in theory, should decrease the incidence rate of the disease. Whether other risk factors for PML can be identified and validated or unique strategies should be employed in association with other DMTs that predispose to PML and whether this has a salutary effect on outcome remains to be demonstrated. Identifying PML early, then promptly eliminating drug in the case of natalizumab-associated PML has demonstrated better outcomes, but the complication of PML continues to carry significant morbidity and mortality. While the scientific community has yet to identify targeted therapy with proven efficacy against JCV or PML there are several candidates being studied.

Brain Susceptibility Changes in a Patient with Natalizumab-Related Progressive Multifocal Leukoencephalopathy: A Longitudinal Quantitative Susceptibility Mapping and Relaxometry Study

Background

Brain MRI plays an essential role in both diagnosis and follow-up of the JC virus infection of the brain. Recently, MR studies with susceptibility-weighted imaging (SWI) sequences have shown hypointensities in U-fibers adjacent to white matter (WM) lesions of progressive multifocal leukoencephalopathy (PML). This finding has been confirmed with the use of quantitative susceptibility mapping (QSM), allowing to hypothesize a paramagnetic effect in these regions. Here, we report the first longitudinal assessment of QSM and R2* maps in natalizumab-associated PML to evaluate serial changes in susceptibility contrast images and their role in PML diagnosis and follow-up.

Case presentation

We report the case of a 42-year-old woman with multiple sclerosis (MS) who eventually developed, after the 28th natalizumab infusion, subacute cognitive decline and received a laboratory-confirmed diagnosis of PML, leading to immediate drug discontinuation. Three months later, she suffered a new clinical exacerbation, with a brain scan revealing significant inflammatory activity compatible with the radiological diagnosis of an Immune Reconstitution Inflammatory Syndrome (IRIS). She was then treated with corticosteroids until the clinico-radiological spectrum became stable, with the final outcome of a severe functional impairment. Quantitative maps obtained in the early symptomatic stage clearly showed increased QSM and R2* values in the juxtacortical WM adjacent to PML lesions, which persisted during the subsequent disease course.

Discussion and conclusion

High QSM and R2* values in U-fibers adjacent to WM lesions were early and seemingly time-independent radiological findings in the presented PML case. This, coupled to the known absence of significant paramagnetic effect of new active MS lesions, could support the use of quantitative MRI as an additional tool in the diagnosis and follow-up of natalizumab-related PML in MS.

Current and Emerging Therapies in Multiple Sclerosis: Implications for the Radiologist, Part 2-Surveillance for Treatment Complications and Disease Progression

An understanding of the new generation of MS drugs in conjunction with the key role MR imaging plays in the detection of disease progression, opportunistic infections, and drug-related adverse effects is of vital importance to the neuroradiologist. Part 1 of this review outlined the current treatment options available for MS and examined the mechanisms of action of the various medications. It also covered specific complications associated with each form of therapy. Part 2, in turn deals with the subject of pharmacovigilance and the optimal frequency of MRI monitoring for each individual patient, depending on his or her unique risk profile. Special attention is given to the diagnosing of progressive multifocal leukoencephalopathy in patients treated with natalizumab as this is a key area in which neuroradiologists can contribute to improved patient outcomes. This article also outlines the aims of treatment and reviews the possibility of "no evidence of disease activity" becoming a treatment goal with the availability of more effective therapies. Potential future areas and technologies including image subtraction, brain volume measurement and advanced imaging techniques such as double inversion recovery are also reviewed. It is anticipated that such advancements in this rapidly developing field will improve the accuracy of monitoring an individual patient's response to treatment.

Progressive Multifocal Leukoencephalopathy in HIV-Uninfected Individuals

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system (CNS) caused by the human neurotropic polyomavirus JC (JCV). The disease occurs virtually exclusively in immunocompromised individuals, and, prior to the introduction of antiretroviral therapy, was seen most commonly in the setting of HIV/AIDS. More recently, however, the incidence of PML in HIV-uninfected persons has increased with broader use of immunosuppressive and immunomodulatory medications utilized in a variety of systemic and neurologic autoimmune disorders. In this review, we discuss the epidemiology and clinical characteristics of PML in HIV-uninfected individuals, as well as diagnostic modalities and the limited treatment options. Moreover, we describe recent findings regarding the neuropathogenesis of PML, with specific focus on the unique association between PML and natalizumab, a monoclonal antibody that prevents trafficking of activated leukocytes into the CNS that is used for the treatment of multiple sclerosis.

Use of quantitative susceptibility mapping (QSM) in progressive multifocal leukoencephalopathy

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is an opportunistic demyelinating encephalopathy related to JC virus. Its characteristics on conventional brain MRI are well known and are important for the diagnosis.

OBJECTIVE

To analyze SWI hypointensities recently described in U-fibers and cortex adjacent to the white matter lesions of PML.

METHODS

Prospective study including four patients with an history of definite diagnosis of PML. Clinical data were collected retrospectively. Brain MRI exams were done on a 3T magnet, including FLAIR, T2 GRE sequences and SWI.

RESULTS

Four males were included (mean age: 47 years, mean PML duration: 24.2 months). Immunosuppression was related to AIDS (n=2), natalizumab for multiple sclerosis (n=1), B-cell lymphoma treated by chemotherapeutic agents and rituximab (n=1). All patients had SWI hypointensities in cortex and/or U-fibers adjacent to the white matter lesions. QSM always suggested a paramagnetic effect.

CONCLUSION

SWI and T2 GRE hypointensities in cortex and U-fibers adjacent to the white matter lesions seem highly prevalent in PML, irrespective of the delay between PML onset and the MRI. QSM data suggest a paramagnetic effect.