Circulating lipoprotein-associated phospholipase A2 in high-grade carotid stenosis: a new biomarker for predicting unstable plaque

OBJECTIVE

To test plasma levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) in patients with high-grade carotid stenosis according to plaque histology.

METHODS

This cross-sectional single-centre study included patients with ≥70% North American Symptomatic Carotid Endarterectomy Trial (NASCET) carotid stenosis, who were treated surgically. Serum Lp-PLA2 and high-sensitivity C-reactive protein (hs-CRP) were determined on the day of surgery. Histopathological analysis classified carotid plaque as stable or unstable, according to AHA classification.

RESULTS

Of the 42 patients (mean age 70.4 ± 10.5 years; 67% men), neurological symptoms were present in 16 (38%). Unstable plaques were found in 23 (55%). Median plasma level of Lp-PLA2 was significantly higher in patients with unstable plaque compared to those with stable plaque (222.4 (174.9-437.5) interquartile range (IQR) 63.5 vs. 211.1 (174.9-270.6) IQR 37.2 ng ml(-1); p = 0.02). Moreover, median Lp-PLA2 level were higher in asymptomatic patients with unstable plaque (226.8 ng ml(-1) (174.9-437.5) IQR 76.8) vs. stable plaque (206.9 ng ml(-1) (174.9-270.6) IQR 33.7; p = 0.16). Logistic regression showed that only the neurological symptoms (OR = 30.9 (3.7-244.6); p < 0.001) and the plasma Lp-PLA2 level (OR = 1.7 (1.1-12.3); p = 0.03) were independently associated with unstable carotid plaque as defined by histology.

CONCLUSIONS

This study showed that circulating Lp-PLA2 was increased in patients with high-grade carotid stenosis and unstable plaque. Lp-PLA2 may be a relevant biomarker to guide for invasive therapy in asymptomatic patients with carotid artery disease.

Progressive dementia associated with ataxia or obesity in patients with Tropheryma whipplei encephalitis

Background

Tropheryma whipplei, the agent of Whipple's disease, causes localised infections in the absence of histological digestive involvement. Our objective is to describe T. whipplei encephalitis.

Methods

We first diagnosed a patient presenting dementia and obesity whose brain biopsy and cerebrospinal fluid specimens contained T. whipplei DNA and who responded dramatically to antibiotic treatment. We subsequently tested cerebrospinal fluid specimens and brain biopsies sent to our laboratory using T. whipplei PCR assays. PAS-staining and T. whipplei immunohistochemistry were also performed on brain biopsies. Analysis was conducted for 824 cerebrospinal fluid specimens and 16 brain biopsies.

Results

We diagnosed seven patients with T. whipplei encephalitis who demonstrated no digestive involvement. Detailed clinical histories were available for 5 of them. Regular PCR that targeted a monocopy sequence, PAS-staining and immunohistochemistry were negative; however, several highly sensitive and specific PCR assays targeting a repeated sequence were positive. Cognitive impairments and ataxia were the most common neurologic manifestations. Weight gain was paradoxically observed for 2 patients. The patients' responses to the antibiotic treatment were dramatic and included weight loss in the obese patients.

Conclusions

We describe a new clinical condition in patients with dementia and obesity or ataxia linked to T. whipplei that may be cured with antibiotics.

1T magnetic resonance imaging in the diagnosis of giant cell arteritis: comparison with ultrasonography and physical examination of temporal arteries

OBJECTIVE

To assess the usefulness of 1T magnetic resonance imaging (MRI) of temporal arteries and to compare 1T MRI with duplex ultrasonography (US) and physical examination of temporal arteries for the diagnosis of giant cell arteritis (GCA) in patients with suspected GCA.

METHOD

The superficial temporal arteries of 20 consecutive patients with a suspected diagnosis of GCA were examined using a 1T MRI scanner. Fat-saturated multislice T1-weighted spin-echo images were acquired perpendicularly to the orientation of the vessel. In all cases, MRI results were compared to US and temporal artery examination findings. Temporal artery biopsies were performed in all patients.

RESULTS

Mural contrast enhancement of the temporal arteries on MRI had a sensitivity of only 33.3% and a specificity of 87.5% for the diagnosis of biopsy-proven GCA. Compared with the diagnosis of GCA by the American College of Rheumatology criteria, MRI had a sensitivity and specificity of 27.2% and 88.9%, respectively. Temporal artery abnormalities on physical examination and the presence of a hypoechoic halo on US had a higher sensitivity (66.7% and 77.7%, respectively) and a higher specificity (100% for both) compared to MRI findings.

CONCLUSION

1T MRI is not useful for the diagnosis of GCA because of its low sensitivity. US and physical examination of temporal arteries had a better diagnostic accuracy. However, our data does not exclude a diagnostic role for higher-resolution MRI.

Postoperative wound infections after breast reductions: the role of smoking and the amount of tissue removed

BACKGROUND

This prospective study followed patients who underwent breast reductions to determine the influence of smoking and the amount of tissue removed on postoperative wound infections.

METHODS

Patients who had received breast reductions were considered eligible for the study. The study excluded postbariatric patients and those with ongoing clinical infections, a recent antibiotic course, or systemic diseases that could impair tissue oxygenation. Smokers were instructed to quit smoking at least 4 weeks before surgery.

RESULTS

By March 2004, the study had enrolled 87 patients. Postoperative infections were present in 24 cases (27.9%). Infections included 16 in smokers (37.2%), 8 in nonsmokers (18.2%; p < 0.05), 14 in patients with large resections (>0.85 kg; 70%), and 10 in patients with small resections (14.9%; p < 0.001). Significant differences were found between the patients who experienced infections and those who were infection free in terms of the overall estimated cigarettes smoked (mean, 146,000; range, 29,200-228,125 vs mean, 10,950; range, 9,125-54,750; p < 0.001), the number of pack years (mean, 20; range, 4-31 vs mean, 2; range, 1-8; p < 0.001), and the amount of tissue removed (mean, 0.9 kg; range, 0.5-2 kg vs mean, 0.5 kg; range, 0.2-1.4 kg; p < 0.001). The analysis for all the patients determined an odds ratio of 2.04 for smoking and 4.7 for the amount of tissue removed.

CONCLUSIONS

Smoking and the amount of tissue removed are important issues in aesthetic breast surgery that need to be addressed accurately by the plastic surgeon. If future larger studies confirm these data, surgeons could have a simple and easy method for stratifying patients according to their risk for the development of wound infections and for prescribing specific preventive measures.

Correlations between MR and endothelial hyperplasia in low-grade gliomas

PURPOSE

To investigate the capacity of multimodal MR to detect endothelial hyperplasia (EH), which has been linked to the aggressiveness of gliomas and which is so far only detected by biopsy, an invasive technique that prevents repeated measurements and early detection.

MATERIALS AND METHODS

A total of 26 patients with low-grade gliomas participated in the study. All underwent a histopathological analysis and a multimodal MR examination (spectroscopic, anatomic, diffusion, perfusion, and postcontrast imaging).

RESULTS

EH was present (EH+) in 15 patients and absent (EH-) in 11. No differences were observed between EH- and EH+ groups when comparing spectroscopic and diffusion parameters. Perfusion measurements, however, allowed us to distinguish EH+ from EH-: the relative regional cerebral blood flow (rCBF) was found equal to 3.23 +/- 2.05 for EH+ and 1.33 +/- 0.46 for EH- (P = 0.006).

CONCLUSION

We have observed a strong correlation between the presence of EH and the increase of rCBF. Compared to conventional imaging, MR perfusion provides additional and complementary information that may be used for biopsy guidance, early detection of tumor aggressiveness, and noninvasive follow-ups.

[Brain magnetic resonance spectroscopy]

MR spectroscopy (MRS) sequences allow noninvasive exploration of brain metabolism during a MRI examination. Their day-to-day use in a clinical setting has recently been improved by simple programming of sequences and automated quantification of metabolites. However, a few simple rules should be observed in the choice of sequences and the location of the voxels so as to obtain an informative, high-quality examination. The research applications of MR spectroscopy, where use of this examination seeks to better understand the pathophysiology of the disease, must be distinguished from its clinical indications, where MRS provides information that can be used directly in patient management. The most significant of the clinical uses are imaging intracranial tumors (positive and differential diagnosis, extension, treatment follow-up), diffuse brain injury, encephalopathies (especially hepatic and HIV-related), and the diagnosis of metabolic disorders.

[Indications for cerebral MR proton spectroscopy in 2007]

Magnetic resonance spectroscopy (MRS) is being increasingly performed alongside the more conventional MRI sequences in the exploration of neurological disorders. It is however important to clearly differentiate its clinical applications aiming at improving the differential diagnosis or the prognostic evaluation of the patient, from the research protocols, when MRS can contribute to a better understanding of the pathophysiology of the disease or to the evaluation of new treatments. The most important applications in clinical practice are intracranial space occupying lesions (especially the positive diagnosis of intracranial abscesses and gliomatosis cerebri and the differential diagnosis between edema and tumor infiltration), alcoholic, hepatic, and HIV-related encephalopathies and the exploration of metabolic diseases. Among the research applications, MRS is widely used in multiple sclerosis, ischemia and brain injury, epilepsy and neuro degenerative diseases.

Spectroscopie par résonance magnétique des tumeurs cérébrales

MR spectroscopy (MRS) can complement MRI in the evaluation of intracranial tumors. Before treatment, MRS can contribute to the differential diagnosis between tumor and non tumoral lesion (especially intracranial abscesses), to assess the aggressiveness of a glial tumor or to determine its extension to better delineate the surgical removal or the target volume of radiotherapy. During treatment follow-up, MRS helps differentiate recurrent tumor from radionecrosis or physiological post-surgical contrast enhancement. The current studies are trying to determine if the indications of MRS, alone or in association with other MR sequences can further be extended in the study of brain tumors, in particular the follow-up of lesions undergoing chemo or radiotherapy.

In vivo and in vitro characterization of skeletal muscle metabolism in patients with statin-induced adverse effects

OBJECTIVE

Statins (3-hydroxymethylglutaryl-coenzyme A reductase inhibitor) are widely used to treat hypercholesterolemia. They are generally well tolerated, but myotoxic effects have been reported and the corresponding mechanisms are still a matter of debate. The aim of the present study was to determine whether impairment of calcium homeostasis and/or mitochondrial impairment could account for the adverse effects of statins in skeletal muscle.

METHODS

Eleven patients with increased creatine kinase levels and myalgias after statin treatment were evaluated using in vitro contracture tests (IVCTs), histology, and 31P magnetic resonance spectroscopy (31P-MRS).

RESULTS

IVCT results were abnormal in 7 of the 9 patients, indicating an impaired calcium homeostasis. The 31P-MRS investigation disclosed no anomaly at rest, and the aerobic function assessed during the postexercise recovery period was normal. On the contrary, the pH recovery kinetics was significantly slowed down as indicated by a reduced proton efflux, which could be ultimately linked to a failure of calcium homeostasis. Overall, our observations indicate a normal mitochondrial function and raise the possibility that statins may unmask a latent pathology involving an impairment of calcium homeostasis such as malignant hyperthermia (MH).

CONCLUSION

In case of susceptibility to MH, statins treatment must be administered with caution, and signs of adverse effects should be checked.

Noninvasive diagnostic assessment of brain tumors using combined in vivo MR imaging and spectroscopy

To determine the potential value of multimodal MRI for the presurgical management of patients with brain tumors, we performed combined magnetic resonance imaging (MRI) and proton MR spectroscopy (MRS) in 164 patients who presented with tumors of various histological subtypes confirmed by surgical biopsy. Univariate statistical analysis of metabolic ratios carried out on the first 121 patients demonstrated significant differences in between-group comparisons, but failed to provide sufficiently robust classification of individual cases. However, a multivariate statistical approach correctly classified the tumors using linear discriminant analysis (LDA) of combined MRI and MRS data. After initial separation of contrast-enhancing and non-contrast-enhancing lesions, 91% of the former and 87% of the latter were correctly classified. The results were stable when this diagnostic strategy was tested on the additional 43 patients included for validation after the initial statistical analysis, with over 90% of correct classification. Combined MRI and MRS had superior diagnostic value compared to MRS alone, especially in the contrast-enhancing group. This study shows the clinical value of a multivariate statistical analysis based on multimodal MRI and MRS for the noninvasive evaluation of intracranial tumors.

Evaluation of N parameter in the staging of non-small cell lung cancer: role of CT and PET

PURPOSE

To determine diagnostic accuracy of CT and FDG-PET for the evaluation of N status in non-small cell lung cancer.

MATERIALS AND METHODS

Thirty-eight CT scans and PET scans of patients with non small-cell lung cancer were retrospectively reviewed. The data of the noninvasive techniques about N status were compared with the pathology findings obtained by standard lymphadenectomy.

RESULTS

The CT results were concordant with surgery in 24 out of 38 cases (63%); in discordant cases CT understaged 8 patients and overstaged 6. The PET images were concordant with surgery in 29 cases (76%); of the remaining 9, PET understaged 5 cases and overstaged 4. Concerning the N parameter, CT had a sensitivity of 42.8% and a specificity of 83.3%, while PET had a sensitivity of 71.4% and a specificity of 91.6%.

CONCLUSIONS

In our experience the diagnostic accuracy of PET is superior to that of CT, in agreement with the most important studies in the literature. On only one occasion did PET fail to differentiate between hilar uptake (N1) and the central primary tumour, an area in which CT provided more precise anatomic details. Nonetheless, we believe that PET should be performed in all patients affected by lung cancer, with the only exception of patients shown to be not suitable for surgery after CT examination.

Dominant form of vanishing white matter-like leukoencephalopathy

Leukoencephalopathy with vanishing white matter syndrome (childhood ataxia with central nervous system hypomyelination/vanishing white matter disease) is an autosomal recessive disorder characterized by the occurrence of acute episodes of deterioration after minor head trauma or infection, and symmetrical demyelination on magnetic resonance with cavitation aspects. Mutations in each of the five subunits of eIF2B have been identified. We report in an affected man and his mother an adult-onset form of childhood ataxia with central nervous system hypomyelination/vanishing white matter disease-like disorder with no mutations in the EIF2B genes and normal guanine nucleotide exchange factor eIF2B activity, suggesting a new dominant inheritance of this syndrome that may involve other genes.

High cerebral scyllo-inositol: a new marker of brain metabolism disturbances induced by chronic alcoholism

Cerebral metabolic changes that concur to motor and/or cognitive disorders in actively drinking alcoholics are not well established. We tested the hypothesis that chronic alcoholics exhibit profound alterations in the cerebral metabolism of scyllo-inositol. Brain metabolism was explored in nine actively drinking and 11 recently detoxified chronic alcoholics by in vivo brain (1)H-MRS and in vitro(1)H-MRS of blood serum and cerebrospinal fluid. The cohort was composed of individuals with acute, subacute or chronic encephalopathy or without any clinical encephalopathy. Chronic alcoholism is associated with a hitherto unrecognized accumulation of brain scyllo-inositol. Our results suggest that scyllo-inositol is produced within the central nervous system and shows a diffuse but heterogenous distribution in brain where it can persist several weeks after detoxification. Its highest levels were observed in subjects with a clinically symptomatic alcohol-related encephalopathy. When detected, brain scyllo-inositol takes part in a metabolic encephalopathy since it is associated with reduced N-acetylaspartate and increased creatine. High levels of cerebral scyllo-inositol are correlated with altered glial and neuronal metabolism. Our findings suggest that the accumulation of scyllo-inositol may precede and take part in the development of symptomatic alcoholic metabolic encephalopathy.

Multimodal magnetic resonance imaging of the central nervous system

The physiological and biochemical properties of the diseased brain that can be explored with magnetic resonance imaging (MRI) are increasing. Progress in MR-based technology affords a large panel of MRI sequences that explore different phenomena and, thus, provide complementary informations. The diagnostic accuracy of MRI is improved by the combination of all MR modalities. However, this abundance of data requires an efficient multiparametric analysis to fully achieve the goal of the multimodal strategy. We will discuss the potential impact of this advanced MRI analysis in the clinical management and the therapeutical strategies of the most common brain pathologies (intracranial tumors, multiple sclerosis, stroke, epilepsy and dementia). This non-invasive approach is of utmost importance since it already improves the diagnosis and the therapeutic choice in the management of several central nervous system diseases.

Metabolic counterpart of decreased apparent diffusion coefficient during hyperacute ischemic stroke: a brain proton magnetic resonance spectroscopic imaging study

BACKGROUND AND PURPOSE

Recent studies have shown that the brain ischemic area defined by the map of decreased apparent diffusion coefficient (ADC) obtained by diffusion-weighted imaging (DWI) during the first hours of ischemic stroke includes a significant part of ischemic penumbra. We hypothesize that the misjudgment of the final infarct size by ADC mapping may be related to a restricted ability of DWI to capture variations in the intensity of cellular suffering. In an attempt to characterize metabolically the hypoperfused brain parenchyma, we studied the relationship between ADC values and brain metabolic parameters measured by proton MR spectroscopic imaging (SI).

METHODS

Six patients with hyperacute ischemic stroke were explored within the first 7 hours after onset with the use of a MR protocol including T2*-weighted MRI, DWI, SI, perfusion-weighted imaging, and MR angiography.

RESULTS

This study demonstrates, for the first time, a wide gradient of ischemia-related metabolic anomalies within the abnormal area delineated by DWI during hyperacute ischemic stroke. In the narrow range of decreased mean ADC values (0.60 to 0.40 x 10(-9) m2 x s(-1)), a 33% decrease in mean ADC is associated with a 122% increase in lactate/N-acetyl aspartate ratio. Mean ADC values never fall below 0.40 x 10(-9) m2 x s(-1) within the severely affected ischemic tissue, while SI still detects a large metabolic heterogeneity inside areas showing similar decreased mean ADC values close to this threshold.

CONCLUSIONS

Our results indicate that the region of very low mean ADC values observed during hyperacute ischemic stroke contains areas of various tissue damage intensity characterized by SI in relation to different stages of cellular metabolic injury. This observation may explain why ADC mapping does not reliably predict final infarct size.

Use of proton magnetic resonance spectroscopy of the brain to differentiate gliomatosis cerebri from low-grade glioma

OBJECT

Gliomatosis cerebri (GC), a rare entity characterized by a widespread infiltration of brain by tumor, lacks objective and quantitative diagnostic criteria. Single-voxel spectroscopy and chemical shift imaging (two-dimensional proton magnetic resonance [MR] spectroscopy) were performed using both short (20- or 22-msec) and long (135-msec) echo times in nine patients suffering from GC, nine patients with low-grade gliomas (LGGs), and 25 healthy volunteers to establish the precise metabolic pattern of this uncommon brain neoplasm.

METHODS

The gliomatosis infiltration was characterized by markedly elevated levels of creatine-phosphocreatine (Cr) and mvo-inositol (Ins), a reduced level of N-acetyl aspartate (NAA), and a moderately elevated level of choline-containing compounds (Cho). This pattern differs strikingly from LGGs, which are characterized by elevated levels of Cho and Ins, markedly reduced levels of NAA, and low-to-normal Cr concentrations. Although the distinction between GC and LGG, based on histological and MR imaging criteria, is a matter of debate, MR spectroscopy produces valuable information for the differentiation between these two entities and, hence, the choice of therapeutic strategy. It also provides new insight into the pathophysiology of GC because elevated Cr and Ins levels may be related to proliferation of glial elements or, more probably, activation of normal glia. Elevated levels of Cho reflect cellular proliferation and reduced NAA corresponds to reversible neuronal injury and/or focal invasion by the tumor process.

CONCLUSIONS

Owing to the unfavorable clinical outcome associated with GC compared with that associated with LGG, the findings of this study illustrate the diagnostic and prognostic value of proton MR spectroscopy in the characterization of infiltrating gliomas.

[Contribution of magnetic resonance spectrometry to the diagnosis of intracranial tumors]

Magnetic resonance spectroscopy (MRS) is a method enabling the analysis of the tissue metabolic content. It may offer a more accurate diagnosis of the intracranial tumors than conventional MRI sequences. MRS of normal brain parenchyma displays 4 main metabolites: N-acetyl aspartate (neuronal marker), creatine (cellular density marker), choline (membrane activity marker) and myoinositol (glial marker); pathological processes lead to variations of the level of these metabolites and/or the appearance of abnormal metabolites (lactate), following different patterns according to pathological process involved: glioma, meningioma, metastasis, bacterial or toxoplasmic abscess, radionecrosis. The potential clinical use of this method includes positive, differential and etiological diagnosis of tumors, determination of the level of malignancy of gliomas, screening for tumor recurrence following treatment. Our laboratory has been performing MR spectroscopic explorations of brain tumors for many years. Based on this experience, we show how MRS can be routinely performed in the clinical setting, what are its limitations and potential, and what kind of information can be supplied to the clinician.