Atypical idiopathic inflammatory demyelinating lesions (IIDL): conventional and diffusion-weighted MR imaging (DWI) findings in 42 cases

Phantom study of layered sensor module for photon-counting BMD detector

In this study, we perform bone mineral density (BMD) calculation by designing a layered sensor module (LSM) that divides high- and low-energy spectra from a single shot of X-rays. Gamma-ray evaluation supports this mechanism; low-energy gamma rays are absorbed in the front detector, whereas high-energy gamma rays are absorbed in the rear detector. In this phantom study, LSM divides a single shot of X-ray into two spectra with different distributions of energy, thereby affording X-ray images with different properties, such as contrast and gray scale. The region of interest (ROI) is classified by the Prewitt operator to sort the pixels for BMD calculation or Rs value. The calculated final value is 1.2051 g/cm2 with a standard deviation (SD) of 0.3690 g/cm2, as obtained from our previous study. An improved SD results from the layered structure with two channels for signal processing, the introduction of Rs value, and the use of Prewitt filter to sort reliable data. Overall, this study displays the feasibility of LSM for BMD calculation with a small error, thereby enabling the diagnosis of osteoporosis with novel mechanism.

Pseudocystic inflammatory demyelinating lesions in multiple sclerosis: A clinical, radiological, and pathological description

BACKGROUND

Pseudocystic inflammatory demyelinating lesions (PIDLs) are poorly described in MS and might represent a diagnostic challenge.

OBJECTIVES

We described the clinical, radiological, pathological, and follow-up characteristics of 13 PIDL in 9 MS patients.

METHODS

We constituted a single-center retrospective case series of PIDLs in MS, defined on MRI as expansive cyst-like lesions, with a fluid-signal content, and a diameter of 1 cm or more.

RESULTS

PIDL often occurred at first event (56%), were often asymptomatic (69%), and encircled by a hypo-T2 diffusion-restricted rim and a thin ring-like gadolinium enhancement (100%) on magnetic resonance imaging (MRI). Associated typical MS lesions were constant. Biopsies from two PIDLs displayed classical features of active MS, except for unusual edema.

CONCLUSION

PIDLs are clinically unremarkable and associated with a good outcome. Their easily recognizable MRI features could help avoid biopsy.

Clinical applications of diffusion-weighted sequence in brain imaging: beyond stroke

Diffusion-weighted imaging (DWI) is a well-established MRI sequence for diagnosing early stroke and provides therapeutic implications. However, DWI yields pertinent information in various other brain pathologies and helps establish a specific diagnosis and management of other central nervous system disorders. Some of these conditions can present with acute changes in neurological status and mimic stroke. This review will focus briefly on diffusion imaging techniques, followed by a more comprehensive description of the utility of DWI in common neurological entities beyond stroke.

Clinical and Radiologic Features, Pathology, and Treatment of Baló Concentric Sclerosis

OBJECTIVE

To describe clinical, radiologic, and pathologic features of Baló concentric sclerosis (BCS) and assess overlap between BCS and other CNS inflammatory demyelinating diseases.

METHODS

Retrospective review of BCS cases from US and Australian tertiary care centers.

RESULTS

We identified 40 BCS cases with 38 available MRIs. Solitary MRI lesions were present in 26% (10/38). We saw >1 active concurrent BCS lesion in 45% (17/38). A third (13/38) had multiple sclerosis-suggestive lesions on the index MRI, of which 10 fulfilled Barkhof criteria. In patients with serial MRI performed within 1 month of the index MRI, lesions expanded radially with sequentially increased numbers of T2 hyperintense rings 52% (14/27). Initially nonenhancing or centrally enhancing lesions subsequently developed single or multiple enhancing rings (41%; 9/22) and incomplete enhancing rings (14%; 3/22). Discordance between rings as they appear on apparent diffusion coefficient, diffusion-weighted imaging, and gadolinium-enhanced imaging was observed in 67% (22/33). Aquaporin-4 immunoglobulin G (n = 26) and myelin oligodendrocyte glycoprotein immunoglobulin G (n = 21) were negative in all patients with serum available. Clinical response to steroid treatment was seen in 46% (13/28). A monophasic clinical course was present in 56% (18/32) at last follow-up (median 27.5 months; range 3-100 months). The initial attack was fatal in 10% (4/40). Median time from symptom onset to death was 23 days (range 19-49 days). All 17 patients with pathology available demonstrated typical findings of multiple sclerosis. Patients with active demyelinating lesions all demonstrated oligodendrocytopathy (pattern III).

CONCLUSIONS

BCS may be a distinct subtype of multiple sclerosis characterized by pattern III immunopathology.

7 Tesla MRI of Balo's concentric sclerosis versus multiple sclerosis lesions

Background

Baló's concentric sclerosis (BCS) is a rare condition characterized by concentrically layered white matter lesions. While its pathogenesis is unknown, hypoxia‐induced tissue injury and chemotactic stimuli have been proposed as potential causes of BCS lesion formation. BCS has been suggested to be a variant of multiple sclerosis (MS). Here, we aimed to elucidate similarities and differences between BCS and MS by describing lesion morphology and localization in high‐resolution 7 Tesla (7 T) magnetic resonance imaging (MRI) scans.

Methods

Ten patients with Baló‐type lesions underwent 7 T MRI, and 10 relapsing remitting MS patients served as controls. The 7 T MR imaging protocol included 3D T₁‐weighted (T₁w) magnetization‐prepared rapid gradient echo, 2D high spatial resolution T₂*‐weighted (T₂*w) fast low‐angle shot and susceptibility‐weighted imaging.

Results

Intralesional veins were visible in the center of all but one Baló‐type lesion. Four Baló‐type lesions displayed inhomogeneous intralesional T₂*w signal intensities, which are suggestive of microhemorrhages or small ectatic venules. Eight of 10 BCS patients presented with 97 additional lesions, 36 of which (37%) had a central vein. Lesions involving the cortical gray matter and the U‐fibers were not detected in BCS patients.

Conclusion

Our findings support the hypothesis that BCS and MS share common pathogenetic mechanisms but patients present with different lesion phenotypes.

High b-value diffusion-weighted imaging in progressive multifocal leukoencephalopathy in HIV patients

Objectives

An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm² (b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm² (b1000).

Methods

We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000.

Results

Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000.

Conclusion

b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis.

Key Points

• B3000 improves contrast resolution between lesion rim, core and normal-appearing white matter.

• B3000 improves identification of the typical rim-and-core pattern of PML lesions.

• B3000 and b1000 similarly identify lesions, but b3000 results in smaller rims and larger cores.

• B3000 excludes some high diffusion components from rim, reclassifying them into core.

• B3000 DWI may provide more precise PML biomarkers of disease activity and tissue damage.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-017-4761-8) contains supplementary material, which is available to authorized users.

Exploring the overlap between multiple sclerosis, tumefactive demyelination and Baló's concentric sclerosis

The availability of magnetic resonance imaging (MRI) has led to increasing recognition that multiple sclerosis (MS), tumefactive demyelination (TD) and Baló's concentric sclerosis (BCS) share many overlapping features. Baló-like lesions, which exhibit limited features of BCS, may represent an intermediate between BCS and typical MS demyelination. Lesions labeled as tumefactive are typically larger, but otherwise have much in common with conventional MS lesions, and TD and BCS lesions can also overlap. In this article, we explore the similarities between typical MS, TD and BCS cases, and reflect on the potential insights that intermediate or overlapping phenotypes may contribute towards an understanding of MS immunopathogenesis, and question whether these atypical forms of demyelination should be classified as separate demyelinating diseases, as different lesional manifestations of demyelination of any cause or as part of a spectrum with conventional MS.

Balo's Concentric Sclerosis with Acute Presentation and Co-Existing Multiple Sclerosis-Typical Lesions on MRI

Balo's disease also known as Balo's concentric sclerosis (BCS) is a rare demyelinating disorder which is characterized pathologically and radiologically by concentric rings of demyelinated and relatively myelin-preserved white matter. We describe the case of a 25-year-old female presenting with stroke-like symptoms who was diagnosed with BCS on MRI. At clinical onset, she also showed co-existing multiple sclerosis (MS)-typical lesions in the brain. This report extends the recent concept that BCS may share similar pathogenesis and radiological progression as MS lesions, that they may occur simultaneously in the same patient and that they may represent different manifestations of the same disease process. Also, BCS needs not be a fulminant disease and may often show a benign self-limiting course as in our case.

Comparison of diffusion-weighted imaging and contrast-enhanced T1-weighted imaging on a single baseline MRI for demonstrating dissemination in time in multiple sclerosis

BACKGROUND

The 2010 Revisions to the McDonald Criteria have established that dissemination in time (DIT) of multiple sclerosis (MS) can be demonstrated by simultaneous presence of asymptomatic gadolinium-enhancing and nonenhancing lesions on a single magnetic resonance imaging (MRI). However, gadolinium-based contrast agents (GBCAs) have contraindications. Diffusion-weighted imaging (DWI) can detect diffusion alterations in active inflammatory lesions. The purpose of this study was to investigate if DWI can be an alternative to contrast-enhanced T1-weighted imaging (CE T1WI) for demonstrating DIT in MS.

METHODS

We selected patients with clinically definite MS and evaluated their baseline brain MRI. Asymptomatic lesions were identified as either hyperintense or nonhyperintense on DWI and enhancing or nonenhancing on CE T1WI. Fisher's exact test was performed to determine whether the hyperintensity on DWI was related to the enhancement on CE T1WI (P < 0.05). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the DWI to predict lesion enhancement were calculated.

RESULTS

Twenty-two patients with 384 demyelinating lesions that were hyperintense on T2-weighted imaging and more than 3 mm in size were recruited. The diffusion hyperintensity and lesion enhancement were significantly correlated (P <0.001). The sensitivity, specificity, PPV, NPV and accuracy were 100%, 67.9%, 32.3%, 100% and 72.1%, respectively.

CONCLUSIONS

A hyperintense DWI finding does not necessarily overlap with contrast enhancement. There are many false positives, possibly representing other stages of lesion development. Although DWI may not replace CE T1WI imaging to demonstrate DIT due to the low PPV, it may serve as a screening MRI sequence where the use of GBCAs is a concern.