Magnetic resonance imaging study of cryptococcal neuroradiological lesions in HIV-negative cryptococcal meningitis

Magnetic resonance (MR) scanning has become an important diagnostic and management tool in cryptococcal meningitis (CM). However, there are only isolated case reports documenting neuroradiological findings in human immunodeficiency virus (HIV)-negative patients with CM and none has clearly addressed the relationship between cerebral lesions on magnetic resonance imaging (MRI) and prognosis. The MR brain images available from 114 HIV-negative patients with CM were retrospectively analysed. Patients were divided into Group I with one or more CM-related lesions and Group II without CM-related lesions. Initial clinical and biochemical markers and prognosis were collected and compared between the two groups. In the present study, the most common pattern of CM-related lesions by MRI was radiological meningitis, following by Virchow–Robin (VR) dilatation, hydrocephalus, intracerebral nodules and pseudocysts, which was different from previous studies reporting that the main MR findings of cerebral cryptococcosis in HIV-infected patients include dilated VR spaces, masses and pseudocysts. Compared to the patients without CM-related lesions, patients with CM-related lesions presented with a higher percentage of male patients, a higher frequency of altered mental status, a higher positive rate of Cryptococcus culture in cerebrospinal fluid (CSF) and a lower ratio of CSF glucose/blood glucose. Poor outcomes were more frequent in patients with presence of CM-related lesions compared to patients without CM-related lesions. In conclusion, the main pattern of cryptococcosis-related lesions on MR scanning differ between non-HIV- and HIV-positive patients with CM. The presence of CM-related lesions was significantly associated with predictors for poor outcome. Neuroimaging on MR scanning is a useful tool to evaluate the initial severity and prognosis of CM without HIV infection.     

Magnetic resonance imaging of pulmonary lesions in guinea pigs infected with Mycobacterium tuberculosis

We utilized magnetic resonance imaging to visualize lesions in the lungs of guinea pigs infected by low-dose aerosol exposure to Mycobacterium tuberculosis. Lesions were prominent in such images, and colorized three-dimensional reconstructions of images revealed a very uniform distribution in the lungs. Lesion numbers after 1 month were approximately similar to the aerosol exposure algorithm, suggesting that each was established by a single bacterium. Numbers of lesions in unprotected and vaccinated animals were similar over the first month but increased thereafter in the control animals, indicating secondary lesion development. Whereas lesion sizes increased progressively in control guinea pigs, lesions remained small in BCG-vaccinated animals. A prominent feature of the disease pathology in unprotected animals was rapid and severe lymphadenopathy of the mediastinal lymph node cluster, which is paradoxical given the strong state of cellular immunity at this time. Further development of this technical approach could be very useful in tracking lesion size, number, and progression in the search for new tuberculosis vaccines.     

Magnetic resonance fast Fourier imaging

A new method for fast magnetic resonance imaging is presented. It provides a more rapid data acquisition than two-dimensional Fourier imaging (2DFI) by a factor which may be chosen depending on the required signal-to-noise ratio of the image. In addition to the readout gradient of 2DFI, the present method employs an oscillating modulation gradient. In this way, a curved alternating trajectory in k space is sampled after each spin excitation. For a p-times accelerated data acquisition, the trajectory consists of p periods, where p is of the order of 2 to 8 for low-frequency gradient modulation but can be chosen higher if certain hardware requirements are met. Adequate sampling density in k space is obtained by scanning shifted trajectories after subsequent spin excitations. The method can be combined with volume imaging (3DFI) and multiple slice 2DFI. It was implemented on a standard Philips Gyroscan system without any hardware modifications. Results obtained for an acceleration factor p = 4 are shown.     

Magnetic resonance metabolic imaging of glioma

2-Hydroxyglutarate (2-HG) is a potential oncometabolite involved in gliomagenesis that has been identified as an aberrant product of isocitrate dehydrogenase (IDH)-mutated glial tumors. Recent genomics studies have shown that heterozygous mutation of IDH genes 1 and 2, present in up to 86% of grade II gliomas, is associated with a favorable outcome. Two reports in this issue describe both ex vivo and in vivo methods that could noninvasively detect the presence of 2-HG in glioma patients. This approach could have valuable implications for diagnosis, prognosis, and stratification of brain tumors, as well as for monitoring of treatment in glioma patients.     

Magnetic resonance acoustic radiation force imaging

Acoustic radiation force impulse imaging is an elastography method developed for ultrasound imaging that maps displacements produced by focused ultrasound pulses systematically applied to different locations. The resulting images are "stiffness weighted" and yield information about local mechanical tissue properties. Here, the feasibility of magnetic resonance acoustic radiation force imaging (MR-ARFI) was tested. Quasistatic MR elastography was used to measure focal displacements using a one-dimensional MRI pulse sequence. A 1.63 or 1.5 MHz transducer supplied ultrasound pulses which were triggered by the magnetic resonance imaging hardware to occur before a displacement-encoding gradient. Displacements in and around the focus were mapped in a tissue-mimicking phantom and in an ex vivo bovine kidney. They were readily observed and increased linearly with acoustic power in the phantom (R2=0.99). At higher acoustic power levels, the displacement substantially increased and was associated with irreversible changes in the phantom. At these levels, transverse displacement components could also be detected. Displacements in the kidney were also observed and increased after thermal ablation. While the measurements need validation, the authors have demonstrated the feasibility of detecting small displacements induced by low-power ultrasound pulses using an efficient magnetic resonance imaging pulse sequence that is compatible with tracking of a dynamically steered ultrasound focal spot, and that the displacement increases with acoustic power. MR-ARFI has potential for elastography or to guide ultrasound therapies that use low-power pulsed ultrasound exposures, such as drug delivery.     

Magnetic resonance imaging in multiple sclerosis

The contribution of magnetic resonance imaging techniques to the clinical prognosis of multiple sclerosis. Magnetic resonance imaging (MRI) is a diagnostic technique with a high sensitivity for the detection of lesions, but with a poor pathological specificity. In the case of multiple sclerosis (MS), the improvement of diagnostic efficacy depends on a careful analysis of the clinical presentation and the use of increasingly stringent MRI criteria aimed at improving the specificity of the conventional MRI T2 sequences. New sequences such as fast spin-echo (also called turbo spin-echo) and FLAIR (fluid attenuated inversion recovery, a method derived from inversion recovery) have improved the visualization of lesions. MRI can under certain conditions be used to monitor the evolution of MS. Acute-phase monitoring is focused on observed changes in disease activity such as the appearance, recurrence or extension of lesions after i.v. injection of contrast medium, i.e., gadolinium (Gd)-enhanced MRI. In the chronic phase, the lesions is the aspect used as the monitoring criterion. However, MRI is still only a secondary criterion in phase III therapeutic trials due to its insufficient correlation with the disability. In neurological daily practice, conventional MRI is only of limited interest at the individual level in patient follow-up, as its prognostic value is poor. Moreover, the difficulty in determining the lesion load can only be excluded in the context of clinical trials, in which certain methodological precautions are taken. This is why techniques other than MRI are being investigated to obtain a better correlation with the clinical course of the disease, for instance the quantification of 'black holes' on T1 weighted images, and the measurement of cerebral and spinal atrophy. Adapted MRI techniques allow a weighted signal to be obtained via the movement (diffusion imaging), by the complexity of the molecular structure (magnetization transfer imaging), by chemical shift (spectroscopic imaging), or by local oxygenation (functional MRI). These new MRI techniques allow a more precise assessment of the pathological mechanisms involved in MS, such as edema, blood brain barrier break-down, demyelinisation, gliosis, cellular infiltration and axonal loss; they provide a better means of establishing the correlation between clinical impact and the destructive nature of the MS lesion. The importance of axonal loss has recently been confirmed in MS by analyzing MRI spectroscopic and neuropathological findings. In addition to magnetization transfer imaging, MR diffusion imaging and functional MRI are being intensively studied in order to assess their contribution to the study of reversibility of the degenerative process.     

Magnetic resonance imaging characteristics of deep endometriosis

The aim of this study was to describe magnetic resonance (MR) imaging findings in histopathologically proven deep endometriosis infiltrating the uterosacral ligaments, the pouch of Douglas, the rectum or the bladder. Twenty patients presenting with a clinical suspicion of deep endometriosis underwent preoperative MR imaging. Sagittal and axial fast T2- and axial T1-weighted spin echo MR sequences were performed. Four patients had post-contrast images. MR results, including morphology and signal intensity of each lesion, were compared to intraoperative gross appearance and histopathology. Histopathology diagnosed 24 lesions of deep endometriosis in the uterosacral ligaments (n = 12), the pouch of Douglas (n = 2), the rectum (n = 3), the bladder (n = 7). Uterosacral ligaments with deep endometriosis were statistically different from normal uterosacral ligaments for proximal nodularity (P = 0.001). There was no difference in signal intensity between normal and abnormal uterosacral ligaments. Contrast-enhanced SE images in four patients with detrusor invasion showed an interruption of the hypointense detrusor by the enhancing bladder endometriosis. Rectal endometriosis was missed in two of three patients and showed non-specific rectal wall thickening in one patient. It is concluded that MR imaging can diagnose deep endometriosis of uterosacral ligaments, the bladder and the pouch of Douglas, but lacks sensitivity in detecting rectal endometriosis without rectal distension.     

Magnetic resonance imaging of the brain stem

Magnetic resonance imaging of 30 normal volonteers' posterior fossae was performed on a CGR Magniscan machine with a magnetic field strength of 0.5 Tesla. We chose the inversion recovery signal with a Tr of 2,000 ms, a TE of 21 ms and an inverse time of 500 ms. This sequence gives a better definition of the grey matter, the white matter and the CSF. To study the brain stem we suggest 8 horizontal and 3 sagittal sections.     

Magnetic resonance imaging of the shoulder anatomy

Magnetic Resonance represents the best method for shoulder study, since it enables us to emphasize all the parts making part of this area thanks to high anatomical details and a comprehensive view of it. Conventional radiographic techniques provide only limited evaluation of soft-tissue anatomy; ultrasonography, on the other hand, allows the visualization of tendons, synovial spaces and muscle fascicles but it is shown to be unfit above all for osseous structure evaluation: TC, finally, is not being employed at present in shoulder study.     

Magnetic resonance imaging of the coraco-acromial ligament

The coraco-acromial ligament is important first for the stability of the shoulder joint and second because it can impinge on the rotator cuff. In this study we demonstrate how the coraco-acromial ligament can be shown by magnetic resonance imaging (MRI) in the axial plane as well as in the more conventional coronal and sagittal planes. Clin. Anat. 10:88–91, 1997 © 1997 Wiley-Liss, Inc.     

Magnetic resonance imaging of prostate cancer.

Over the past 10 years, dramatic developments in hardware and software have made magnetic resonance imaging a very powerful diagnostic tool for imaging body organs. In this review, the technique as it applies to prostate imaging is discussed, and the literature is reviewed to provide an overview of the current status of prostate magnetic resonance imaging as a tool for diagnosis and staging of prostate cancer.     

Magnetic resonance imaging and histopathological study of brain lesions in rabbits given intravenous verotoxin 2.

When rabbits were given intravenously purified verotoxin 2 (VT2) at 5 microg/kg of body weight, they developed hemorrhagic diarrhea, flaccid paresis, an ataxic gait, an opisthotonic posture, and convulsions. To examine the effects of VT2 toxemia on the rabbit central nervous system, magnetic resonance imaging and ultrastructural studies were performed. At 24, 57, and 80 h after injection of VT2 into 12 rabbits, T2-weighted images of the central nervous system were obtained. The initial lesion was noted at 24 h in the hypothalamic areas of all experimental animals. At 57 h, the T2 value increased in the medulla of the cerebral hemisphere or the hippocampus, with a brain stem lesion in six rabbits (50%). The rabbits with the brain stem lesions, in which neurological signs were very severe, died within 6 days. Lesions in the cerebellar hemisphere and/or vermis were noted in four rabbits (33%) that survived more than 1 month. To better understand the pathogenesis of VT2 in these brain lesions, we examined the deterioration of the blood-brain barrier and cerebrospinal fluid-brain barrier by using horseradish peroxidase as a tracer. The tracer was detected by electron microscopy both in the subendothelial layer, including the basal lamina, and throughout the cytoplasm of the ependymal cell layer covering the ventricle after intravenous or intrathecal treatment with horseradish peroxidase. We also determined the localization of VT2 by immunoelectron microscopy and found that it was localized on edematous endothelial cells of capillaries, ependymal cells, and myelin sheaths. The present study suggests that VT2 was conveyed from the endothelial and ependymal cell layers and caused edematous changes in the rabbit brain.     

Role of FNAC in palpable chest wall lesions in developing country

Palpable chest wall lesions are unusual manifestation of an underlying thoracic pathology and it is difficult to diagnose them with their diverse spectrum ranging from benign to malignant. Considering the exposure of patient to invasive biopsy/excision and the risk of local complications, FNAC is now being increasingly used in the primary assessment of these lesions. Objectives of this study were to report the spectrum of chest wall lesions in the population of a developing country and evaluating the diagnostic role of FNAC. All the patients who presented with palpable cutaneous or subcutaneous chest wall swelling during a period of January 2003 to August 2010 were reviewed retrospectively. May Grunwald Giemsa and Papanicolaou stained aspirates were examined, along with special stains. Seven hundred seventy‐three cases were subjected to chest wall FNAC, of which 726 (93.9%) cases were satisfactory. Age ranged from 1 to 93 years with M:F = 0.92:1. 358 (49.3%) were diagnosed as inflammatory and 368 (50.7%) were neoplastic lesions. Two‐hundred thirty four cases (32.2%) were diagnosed as mycobacterial abscess (likely tuberculous). Of the neoplastic lesions, 153 were malignant with carcinomas being predominant (88.2%). Malignant cases comprised of scar site recurrence in breast carcinoma (73 cases), metastatic carcinomas (62 cases), primary sarcomas (eight cases), hematological neoplasms (six cases), and miscellaneous group (four cases). Overall malignant lesions accounted for 21.1% (153/726) of satisfactory chest wall aspirates. FNAC is very useful and simple investigation for early diagnosis of chest wall abscesses, cutaneous metastases from visceral malignancies, and scar site recurrence in breast carcinoma. Diagn. Cytopathol. 2014;42:653–659. © 2014 Wiley Periodicals, Inc.     

Magnetic resonance imaging of the rat Harderian gland

The intra-orbital lacrimal gland (Harderian gland, or HG) of the female rat was studied by magnetic resonance imaging (MRI) to evaluate whether MRI can be used to visualize the gland in vivo and localized-1H-spectroscopy detect its lipid content. The results were correlated with post-mortem anatomical sections, and with light and electron microscopy. On MRI, HG presented as a mass located between the ocular bulb and the orbit. In strongly T2W sequences the secretory structures had a reduced signal while intraparenchymal connective tissue was visible. T2-quantitative maps values of HG (60.12 +/- 8.15 ms, mean +/- SD) were different from other tissues (i.e. muscular tissue, T2 = 44.79 +/- 3.43 ms and olfactory bulb, T2 = 79.26 +/- 4.25 ms). In contrast-enhanced-MRI, HG had a signal-intensity-drop of 0.074 +/- 0.072 (mean +/- SD), after injection of AMI-25, significantly different from the muscle (0.17 +/- 0.10). Localized MRI spectra gave a large part of the signal originating from fat protons, but with a significant percentage from water protons. At light and electron microscopy the lipid deposition appeared to be composed of low-density material filling a large part of the cytoplasm, and the porphyrin aggregates were easily recognizable. The data demonstrate that an in vivo study of the HG was feasible and that high-field MRI allowed analysis of the gross anatomy detecting the lipid content of the gland.     

Magnetic resonance imaging of infratentorial congenital brain malformations

The common infratentorial congenital malformations of the brain were analyzed with magnetic resonance imaging at the Children's Memorial Hospital in Chicago over a 2-year period. Over 200 children with one of the following congenital malformations were imaged using magnetic resonance: Dandy-Walker malformations, Chiari malformations, and cerebellar aplasia-hypoplasia malformations. The characteristic findings in each of these disorders are described based on the magnetic resonance image scans along with the clinical spectrum.