RANCM: a new ranking scheme for assigning confidence levels to metabolite assignments in NMR-based metabolomics studies.

INTRODUCTION: The Metabolomics Standards Initiative has recommended four categories for metabolite assignments in NMR-based metabolic profiling studies. The "putatively annotated compound" category is most commonly reported by metabolomics investigators. However, there is significant ambiguity in reliability of "putatively annotated compound" assignments, which can range from low confidence made on minimal corroborating data to high confidence made on substantial corroborating data. OBJECTIVES: To introduce a new ranking system, Rank and AssigN Confidence to Metabolites (RANCM), to assign confidence levels to "putatively annotated compound" assignments in NMR-based metabolic profiling studies. METHODS: The ranking system was constructed with three confidence levels ranging from Rank 1 for the lowest confidence assignment level to Rank 3 for the highest confidence assignment level. A decision tree was constructed to guide rank selection for each metabolite assignment. RESULTS: Examples are provided from experimental data demonstrating how to use the decision tree to make confidence level assignments to "putatively annotated compounds" in each of the three rank levels. A standard Excel sheet template is provided to facilitate decision-making, documentation and submission to data repositories. CONCLUSION: RANCM is intended to reduce the ambiguity in "putatively annotated compound" assignments, to facilitate effective communication of the degree of confidence in "putatively annotated compound" assignments, and to make it easier for non-experts to evaluate the significance and reliability of NMR-based metabonomics studies. The system is straightforward to implement, based on the most common datasets collected in NMR-based metabolic profiling studies, and can be used with equal rigor and significance with any set of NMR datasets.

Resonancia magnética multiparamétrica y cáncer de próstata: ¿qué hay de nuevo? / Multiparametric magnetic resonance imaging and prostate cancer: what's new?

La resonancia magnética multiparamétrica (RMmp) prostática ha tenido recientemente un extenso desarrollo, convirtiéndose en una herramienta clave en el diagnóstico y la toma de decisiones terapéuticas en relación al carcinoma prostático (CaP). El rápido desarrollo tecnológico, así como de lectura (PIRADS V2), exigen una permanente actualización del conocimiento en esta área. El objetivo de este artículo es presentar una revisión actualizada sobre los aspectos técnicos, los modelos de lectura y las indicaciones de la RMmp prostática en relación al CaP, en el marco de una visión multidisciplinaria. Actualmente está establecida la utilidad de la RMmp ante un antígeno específico de próstata elevado y una biopsia prostática previa negativa; para estadificación tumoral; en la evaluación de candidatos a vigilancia activa; en la planificación de tratamientos focales y para la evaluación de la recurrencia tumoral. Otras indicaciones, como su uso en pacientes con sospecha de CaP pero sin biopsia previa, aunque se realizan en algunos centros, aún requieren una exhaustiva valoración coste-beneficio para extender su empleo (AU)

Prostatic multi-parametric magnetic resonance imaging (MP-MRI) has recently had a wide development becoming a key tool in the diagnostic and therapeutic decisions in prostate cancer (Pca). The fast development both in technology and in reading (PIRADS V2) requires a continuous updating of knowledge within this area. The aim of this article is to present an updated revision of technical aspects, reading patterns and prostatic MP-MRI in Pca, with a multidisciplinary approach. Currently guidelines establish the use of the MP-MRI when there is a high PSA and a negative prostatic biopsy; tumor staging; evaluation in candidates to active surveillance; focal treatments plans and tumoral recurrence evaluation. Although it is used in other indications in some centers, like its use in patients suspicious of Pca but with no previous biopsy, there is still the need of a cost/benefit assessment for its use to be wider (AU)

Resección laparoscópica de un tumor virilizante suprarrenal derecho / Laparoscopic approach in an adrenal right virilizing tumour

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Resonancia magnética en la planificación de la braquiterapia intracavitaria para el tratamiento del cáncer de cérvix localmente avanzado / Magnetic resonance imaging for planning intracavitary brachytherapy for the treatment of locally advanced cervical cancer

El cáncer de cérvix es el tercer cáncer ginecológico más frecuente. El tratamiento depende de la estadificación del tumor en el momento del diagnóstico, siendo la combinación de quimioterapia y radioterapia el tratamiento de elección para cánceres localmente avanzados. El uso combinado de radioterapia externa y braquiterapia aumenta la supervivencia en estas pacientes. La braquiterapia permite proporcionar mayor dosis de radiación al tumor con menor toxicidad de los tejidos vecinos en comparación con la radioterapia externa exclusiva. La planificación de la braquiterapia se ha realizado durante años exclusivamente con tomografía computarizada (TC). La reciente incorporación de la resonancia magnética (RM) ha demostrado que aporta información esencial del tumor y de las estructuras vecinas, y permite definir mejor los volúmenes blanco. No obstante, la RM presenta limitaciones, algunas de las cuales se pueden compensar con la fusión de imágenes de TC y RM, con lo que se consigue una planificación óptima al combinar las ventajas de cada técnica (AU)

Cervical cancer is the third most common gynecological cancer. Its treatment depends on tumor staging at the time of diagnosis, and a combination of chemotherapy and radiotherapy is the treatment of choice in locally advanced cervical cancers. The combined use of external beam radiotherapy and brachytherapy increases survival in these patients. Brachytherapy enables a larger dose of radiation to be delivered to the tumor with less toxicity for neighboring tissues with less toxicity for neighboring tissues compared to the use of external beam radiotherapy alone. For years, brachytherapy was planned exclusively using computed tomography (CT). The recent incorporation of magnetic resonance imaging (MRI) provides essential information about the tumor and neighboring structures making possible to better define the target volumes. Nevertheless, MRI has limitations, some of which can be compensated for by fusing CT and MRI. Fusing the images from the two techniques ensures optimal planning by combining the advantages of each technique (AU)

Clasificación de las lesiones estructurales en resonancia magnética. Implicaciones quirúrgicas en pacientes con epilepsia farmacorresistente / Classification of structural lesions in magnetic resonance imaging. Surgical implications in drug-resistant epilepsy patients.

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Conventions and nomenclature for double diffusion encoding NMR and MRI.

Stejskal and Tanner's ingenious pulsed field gradient design from 1965 has made diffusion NMR and MRI the mainstay of most studies seeking to resolve microstructural information in porous systems in general and biological systems in particular. Methods extending beyond Stejskal and Tanner's design, such as double diffusion encoding (DDE) NMR and MRI, may provide novel quantifiable metrics that are less easily inferred from conventional diffusion acquisitions. Despite the growing interest on the topic, the terminology for the pulse sequences, their parameters, and the metrics that can be derived from them remains inconsistent and disparate among groups active in DDE. Here, we present a consensus of those groups on terminology for DDE sequences and associated concepts. Furthermore, the regimes in which DDE metrics appear to provide microstructural information that cannot be achieved using more conventional counterparts (in a model-free fashion) are elucidated. We highlight in particular DDE's potential for determining microscopic diffusion anisotropy and microscopic fractional anisotropy, which offer metrics of microscopic features independent of orientation dispersion and thus provide information complementary to the standard, macroscopic, fractional anisotropy conventionally obtained by diffusion MR. Finally, we discuss future vistas and perspectives for DDE.

Distrofia fascial congénita o síndrome de la piel rígida: presentación de un caso / Congenital Fascial Dystrophy or Stiff Skin Syndrome: A Case Report

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Nuevos criterios ASAS para el diagnóstico de espondiloartritis. Diagnóstico de sacroileítis por resonancia magnética / New ASAS criteria for the diagnosis of spondyloarthritis: Diagnosing sacroiliitis by magnetic resonance imaging

La sacroileítis radiográfica ha formado parte del diagnóstico de las espondiloartropatías desde su inclusión en los criterios de Roma en 1961. Sin embargo, en la última década, la resonancia magnética (RM) ha demostrado ser más sensible para valorar las articulaciones sacroilíacas en los pacientes con sospecha de espondiloartritis y síntomas de sacroileítis, no solo para diagnosticarla, sino también para seguir la evolución de la enfermedad y el tratamiento de estos pacientes. El grupo The Assessment of SpondyloArthritis international Society (ASAS) desarrolló en el año 2009 unos criterios para clasificar y diagnosticar a los pacientes con espondiloartritis, entre los que destacaba la inclusión de un estudio de RM positivo para sacroileítis como criterio diagnóstico mayor. Este artículo incide en la parte radiológica de esta clasificación. Se describen e ilustran las diferentes alteraciones que podemos encontrarnos en los estudios de RM en pacientes con sacroileítis, resaltando las limitaciones y potenciales errores diagnósticos (AU)

Radiographic sacroiliitis has been included in the diagnostic criteria for spondyloarthropathies since the Rome criteria were defined in 1961. However, in the last ten years, magnetic resonance imaging (MRI) has proven more sensitive in the evaluation of the sacroiliac joints in patients with suspected spondyloarthritis and symptoms of sacroiliitis; MRI has proven its usefulness not only for diagnosis of this disease, but also for the follow-up of the disease and response to treatment in these patients. In 2009, The Assessment of SpondyloArthritis international Society (ASAS) developed a new set of criteria for classifying and diagnosing patients with spondyloarthritis; one important development with respect to previous classifications is the inclusion of MRI positive for sacroiliitis as a major diagnostic criterion. This article focuses on the radiologic part of the new classification. We describe and illustrate the different alterations that can be seen on MRI in patients with sacroiliitis, pointing out the limitations of the technique and diagnostic pitfalls (AU)

Classification of single-voxel 1H spectra of brain tumours using LCModel.

This study presents a novel method for the direct classification of (1)H single-voxel MR brain tumour spectra using the widespread analysis tool LCModel. LCModel is designed to estimate individual metabolite proportions by fitting a linear combination of in vitro metabolite spectra to an in vivo MR spectrum. In this study, it is used to fit representations of complete tumour spectra and to perform a classification according to the highest estimated tissue proportion. Each tumour type is represented by two spectra, a mean component and a variability term, as calculated using a principal component analysis of a training dataset. In the same manner, a mean component and a variability term for normal white matter are also added into the analysis to allow a mixed tissue approach. An unbiased evaluation of the method is carried out through the automatic selection of training and test sets using the Kennard and Stone algorithm, and a comparison of LCModel classification results with those of the INTERPRET Decision Support System (IDSS) which incorporates an advanced pattern recognition method. In a test set of 46 spectra comprising glioblastoma multiforme, low-grade gliomas and meningiomas, LCModel gives a classification accuracy of 90% compared with an accuracy of 95% by IDSS.

Application of HR-MAS NMR in the solid-phase synthesis of a glycopeptide using Sieber amide resin.

The solid-phase synthesis (SPS) of a structurally complex glycopeptide, using Sieber amide resin, was monitored by high resolution magic angle spinning NMR, demonstrating the further application of this technique. A synthetic peptidoglycan derivative, a precursor of a biologically active PGN, known to be involved in the cellular recognition, was prepared by SPS. The synthesis involved the preparation of an N-alloc glucosamine moiety and the synthesis of a simple amino acid sequence L-Ala-D-Glu-L-Lys-D-Ala-D-Ala. Last step consisted the coupling, on solid-phase, of the protected muramyl unit to the peptide chain. Proton spectra with good suppression of the polystyrene signals in swollen resin samples were obtained in DMF-d(7) as a solvent and by using a nonselective 1D TOCSY/DIPSI-2 scheme, thus allowing to follow the SPS without losses of compound and cleavage from the resin. The assignment of the proton spectra of the resin-bound amino acid sequence and of the bound glycopeptide was achieved through the combination of MAS COSY, TOCSY and NOESY.

Unsupervised feature dimension reduction for classification of MR spectra.

We present an unsupervised feature dimension reduction method for the classification of magnetic resonance spectra. The technique preserves spectral information, important for disease profiling. We propose to use this technique as a preprocessing step for computationally demanding wrapper-based feature subset selection. We show that the classification accuracy on an independent test set can be sustained while achieving considerable feature reduction. Our method is applicable to other classification techniques, such as neural networks, support vector machines, etc.

Índice de complejidad en resonancia magnética: estudio basado en una escala de unidades relativas / Complexity index as applied to magnetic resonance: study based on a scale of relative units

Objetivo: Analizar la utilidad y las repercusiones de medir la actividad de resonancia magnética (RM) en unidades de actividad radiológica (UAR) y de emplear el índice de complejidad (IC) como indicador de actividad. Material y método: Estudiamos la actividad de Osatek, S.A. en el ámbito de la RM, en un período de ocho años (1994-2001). Medimos dicha actividad en número de estudios de RM y en UAR, basándonos en la escala de unidades relativas publicada en la "Guía de gestión de los servicios de radiología" editada por la Sociedad Española de Radiología Médica (SERAM). Calculamos el índice de complejidad anual, entendido como el cociente entre número de RM y valor en UAR, y analizamos factores que pueden incidir en el IC: tipo de exploraciones y potencia de campo magnético del equipo. Resultados: El IC se mantiene prácticamente estable los primeros cuatro años del estudio, mientras que los cuatro últimos años experimenta una tendencia creciente. Existe un paralelismo entre esta tendencia y el porcentaje de exploraciones que denominamos complejas (fundamentalmente cuerpo y angio-RM). Conclusiones: El incremento de la complejidad de los estudios de RM en los últimos años es demostrable a través del IC. La medida de la producción de RM en UAR expresa con mayor realismo que el número de exploraciones la actividad asistencial desarrollada por un centro, y permite comparaciones externas. El IC es un indicador útil, que puede ser empleado como herramienta de gestión (AU)

Orthogonal subspace projection-based approaches to classification of MR image sequences.

Orthogonal subspace projection (OSP) approach has shown success in hyperspectral image classification. Recently, the feasibility of applying OSP to multispectral image classification was also demonstrated via SPOT (Satellite Pour 1'Observation de la Terra) and Landsat (Land Satellite) images. Since an MR (magnetic resonance) image sequence is also acquired by multiple spectral channels (bands), this paper presents a new application of OSP in MR image classification. The idea is to model an MR image pixel in the sequence as a linear mixture of substances (such as white matter, gray matter, cerebral spinal fluid) of interest from which each of these substances can be classified by a specific subspace projection operator followed by a desired matched filter. The experimental results show that OSP provides a promising alternative to existing MR image classification techniques.

Papel de la resonancia magnética en la patología testicular y paratesticular / Role of magnetic resonance in testicular and paratesticular disease

Objetivo: Analizar y describir los hallazgos diagnósticos más relevantes en la patología testicular y paratesticular mediante Resonancia Magnética. Material y métodos: Se analizan 78 pacientes seleccionados ecográficamente, en los cuales se observó patología testicular o paratesticular, y en aquellos con sospecha clínica de enfermedad y ecografía no concluyente. Se utilizó una unidad de resonancia magnética (RM) de 0,5 T (Gyroscan T5, Philips) usando una bobina de superficie fijada sobre una sábana que cubría la región testicular. Se emplearon secuencias T1 eco del espín precontraste y poscontrate (TR/TE: 572/20, FOV: 180 mm, grosor: 6 mm, gap: 0,6 mm y matriz: 256 × 256) T2 FSE (TR/TE: 3257/120) y STIR. En todos los casos se llegó al diagnóstico definitivo mediante resultados anatomopatológicos o seguimiento. Resultados: Las secuencias potenciadas en T2 valoran el parénquima testicular por tener una señal alta, diferenciándose el epidídimo por su hipointensidad. En el escroto agudo la RM alcanzó una sensibilidad, especificidad e índice kappa del 100 por ciento. En los tumores no se obtuvo mayor rendimiento diagnóstico que la ecografía salvo en el tumor de Leydig el cual mostró un gran realce tras la administración de contraste. La capacidad multiplanar fue de especial importancia en la localización intratesticular o extratesticular de las lesiones. Conclusiones: Aunque la ecografía representa la primera técnica diagnóstica en las enfermedades escrotales hemos de considerar la RM como una técnica no sólo de apoyo en aquellos casos que no sean concluyentes, sino también de especial importancia en entidades como el escroto agudo y especialmente en los casos de torsión testicular (AU)

Fuzzy pre-processing of gold standards as applied to biomedical spectra classification.

Fuzzy gold standard adjustment is a novel fuzzy set theoretic pre-processing strategy that compensates for the possible imprecision of a well-established gold standard (reference test) by adjusting, if necessary, the class labels in the design set while maintaining the gold standard's discriminatory power. The adjusted gold standard incorporates robust within-class centroid information. This strategy was applied to biomedical data acquired from a MR spectrometer for the purpose of classifying human brain neoplasms. It is shown that consistent improvement (10-13%) to the discriminatory power of the underlying classifier is obtained when using this pre-processing strategy.

Focal brain lesions: effect of single-voxel proton MR spectroscopic findings on treatment decisions.

PURPOSE: To determine the influence of single-voxel proton magnetic resonance (MR) spectroscopic findings on the treatment of patients suspected of having a brain tumor. MATERIALS AND METHODS: Medical records were reviewed in 78 patients who underwent MR spectroscopy for evaluation of a focal brain mass suspected of being neoplastic. MR spectroscopic findings were positive for neoplasm in 49 patients and negative in 29. Treatment with or without performance of biopsy was noted. In patients with positive findings who underwent irradiation or chemotherapy without biopsy and in patients with negative findings who were treated medically or followed up for interval changes, MR spectroscopy was classified as having a potential positive influence on treatment. In patients with positive findings with subsequently proved nonneoplastic lesions and in patients with negative findings with subsequently proved tumors, MR spectroscopy was classified as having a potential negative influence. RESULTS: MR spectroscopy in eight (16%) patients with positive findings and in 15 (52%) patients with negative findings had a potential positive influence on treatment. In two (3%) patients, MR spectroscopy had a potential negative influence. CONCLUSION: MR spectroscopy may play a beneficial role in the management of suspected brain tumors. Prospective studies are needed to test the effect of MR spectroscopy on clinical practice and to measure costs and benefits.

Computerized consensus diagnosis: a classification strategy for the robust analysis of MR spectra. I. Application to 1H spectra of thyroid neoplasms.

We introduce and apply a new classification strategy we call computerized consensus diagnosis (CCD). Its purpose is to provide robust, reliable classification of biomedical data. The strategy involves the cross-validated training of several classifiers of diverse conceptual and methodological origin on the same data, and appropriately combining their outcomes. The strategy is tested on proton magnetic resonance spectra of human thyroid biopsies, which are successfully allocated to normal or carcinoma classes. We used Linear Discriminant Analysis, a Neural Net-based method, and Genetic Programming as independent classifiers on two spectral regions, and chose the median of the six classification outcomes as the consensus. This procedure yielded 100% specificity and 100% sensitivity on the training sets, and 100% specificity and 98% sensitivity on samples of known malignancy in the test sets. We discuss the necessary steps any classification approach must take to guarantee reliability, and stress the importance of fuzziness and undecidability in robust classification.