Resonancia magnética dinámica de mama: estudio comparativo de gadobutrol y Gd-DTPA

Objective

To compare the pharmacokinetic profile of gadobutrol versus Gd-DTPA in dynamic contrast-enhanced MRI (DCE-MRI) in patients with breast cancer. Secondary objectives included comparing the safety profiles and diagnostic efficacy of the two contrast agents for detecting additional malignant lesions.

¿Podría ser útil la resonancia magnética de estrés en pacientes con baja probabilidad de cardiopatía isquémica?

Objective

To assess the usefulness of cardiac stress magnetic resonance imaging (MRI) with adenosine in the detection of ischemic heart disease in patients with a low pretest probability of disease.

Bases de la imagen funcional II: técnicas emergentes de resonancia magnética y nuevos métodos de análisis

Current multiparameter MRI protocols integrate structural, physiological, and metabolic information about cancer. Emerging techniques such as arterial spin-labeling (ASL), blood oxygen level dependent (BOLD), MR elastography, chemical exchange saturation transfer (CEST), and hyperpolarization provide new information and will likely be integrated into daily clinical practice in the near future. Furthermore, there is great interest in the study of tumor heterogeneity as a prognostic factor and in relation to resistance to treatment, and this interest is leading to the application of new methods of analysis of multiparametric protocols. In parallel, new oncologic biomarkers that integrate the information from MR with clinical, laboratory, genetic, and histologic findings are being developed, thanks to the application of big data and artificial intelligence. This review analyzes different emerging MR techniques that are able to evaluate the physiological, metabolic, and mechanical characteristics of cancer, as well as the main clinical applications of these techniques. In addition, it summarizes the most novel methods of analysis of functional radiologic information in oncology.     

Resonancia magnética dinámica en el diagnóstico de las lesiones tumorales y seudotumorales del sistema musculoesquelético

The greater temporal resolution provided in ultrafast dynamic contrast-enhanced magnetic resonance imaging sequences makes it possible to know the physiological phenomenon of the distribution of the contrast material through a time-signal intensity curve. Analyzing these curves enables us to deduce information relevant to the vascularization and perfusion of tissues, capillary permeability, and the interstitial space in the tumor. A steep curve with early washout in a space-occupying lesion greatly increases the possibility of histological malignancy, although this type of curve is not rare in benign lesions and relatively flat curves are not rare in malignant tumors. Nevertheless, dynamic studies of the uptake of contrast material provide important information for the characterization of neoplasms that, together with the usual signs, can help to differentiate between benign and malignant tumors of adipocyte, chondroid, or neural lineage, clearing up diagnostic uncertainty in certain benign lesions such as osteoid osteoma and ischemic musculoskeletal disease. Furthermore, it enables the accurate determination of the response to chemotherapy, detecting recurrence within the treated tumor early, delimiting more precisely the margins between the tumor and peritumoral edema, and helping in diagnostic planning by determining the most vascularized areas of the tumor, which are more likely to be malignant.     

Papel complementario de la resonancia magnética en el estudio del sistema urinario fetal

Urinary system birth defects represent the abnormality most often detected in prenatal studies, accounting for 30% to 50% of all structural anomalies present at birth. The most common disorders are urinary tract dilation, developmental variants, cystic kidney diseases, kidney tumors, and bladder defects. These anomalies can present in isolation or in association with various syndromes. They are normally evaluated with sonography, and the use of magnetic resonance imaging (MRI) is considered only in inconclusive cases. In this article, we show the potential of fetal MRI as a technique to complement sonography in the study of fetal urinary system anomalies. We show the additional information that MRI can provide in each entity, especially in the evaluation of kidney function through diffusion-weighted sequences.     

Variación de tamaño de la hiperplasia nodular focal mediante resonancia magnética

ObjectiveTo evaluate the changes in the size of focal nodular hyperplasia (FNH) during long-term magnetic resonance imaging (MRI) follow-up.Material and methodsWe reviewed 44 FNHs in 30 patients studied with MRI with at least two MRI studies at least 12 months apart. We measured the largest diameter of the lesion (in mm) in contrast-enhanced axial images and calculated the percentage of variation as the difference between the maximum diameter in the follow-up and the maximum diameter in the initial study. We defined significant variation in size as variation greater than 20%. We also analyzed predisposing hormonal factors.ResultsThe mean interval between the two imaging studies was 35 ± 2 months (range: 12-94). Most lesions (80%) remained stable during follow-up. Only 9 of the 44 lesions (20%) showed a significant variation in diameter: 7 (16%) decreased in size and 2 (4%) increased, with variations that reached the double of the initial size. The change in size was not related to pregnancy, menopause, or the use of birth control pills or corticoids.ConclusionChanges in the size of FNHs during follow-up are relatively common and should not lead to a change in the diagnosis. These variations in size seem to be independent of hormonal factors that are considered to predispose.     

Resonancia magnética en la planificación de la braquiterapia intracavitaria para el tratamiento del cáncer de cérvix localmente avanzado

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.     

¿Es necesaria la resonancia magnética en la patología musculotendinosa?

Disorders of the musculoskeletal system are very prevalent in our society, especially those involving muscles and tendons, above all related to sports and work. These conditions are normally diagnosed and treated according to their clinical symptoms and signs, but a precise diagnosis is often necessary. The most widely used techniques for diagnosing these conditions are ultrasonography and magnetic resonance imaging. In this article, we propose ultrasonography as the technique of choice for diagnosing the most prevalent musculotendinous diseases, because it is accurate, versatile, dynamic, and effective.     

¿Es efectiva la realización previa de resonancia magnética multiparamétrica en pacientes candidatos a biopsia prostática? Estudio CAT

We carried out a critically appraised topic (CAT)-type study to determine whether the relevant scientific evidence supports the recommendation of doing a multiparametric magnetic resonance imaging study of the prostate in all patients who are candidates for prostate biopsy with the aim of improving the detection of clinically significant prostate cancer and stratifying patients to receive active surveillance or treatment. After a formal literature search and an analysis of the two most relevant articles it found, we reached the conclusion that, despite promising results that point to the potential usefulness of this approach, there is still not enough clear scientific evidence to endorse it categorically. Before this approach can be endorsed, we need evidence from well-designed prospective randomized trials using widely agreed upon criteria and including large numbers of patients at multiple centers.     

Aplicaciones de la técnica de difusión por resonancia magnética en el manejo de la patología tumoral osteomuscular

Magnetic resonance imaging (MRI) is the technique of choice in the diagnosis, staging, and follow-up of musculoskeletal tumors. Diffusion imaging is a new functional MRI technique that provides information that is complementary to that obtained in conventional MRI sequences. Diffusion imaging has proven useful in different clinical situations like the characterization of disease involving the bone marrow (bone metastases, benign fractures, or hematological disease), the evaluation of tumors of the bones and soft tissues, and the monitoring of the response to treatment in patients with tumors. The aim of this article is to review the diffusion technique in MRI and its current clinical applications in the management of musculoskeletal tumors.     

Imagen por resonancia magnética en la estadificación y planificación del tratamiento del cáncer de cérvix

ObjectiveTo review the key points that are essential for the correct staging of cervical cancer by magnetic resonance imaging.ConclusionMagnetic resonance imaging is the method of choice for locoregional staging of cervical cancer. Thorough evaluation of prognostic factors such as tumor size, invasion of adjacent structures, and the presence of lymph node metastases is fundamental for planning appropriate treatment.     

Técnicas avanzadas de resonancia magnética en patología tumoral de cabeza y cuello

Magnetic resonance imaging has become a fundamental tool for the evaluation of head and neck tumors. The anatomic details that magnetic resonance images provide are fundamental for diagnosing, characterizing, and staging both primary tumors and lymph node metastases.In addition to technical improvements in anatomic sequences, such as Dixon techniques to improve fat suppression, other sequences being developed, such as diffusion and perfusion, provide molecular, biological, and physiological information about the tumor and are yielding imaging biomarkers that can help in determining the tumor's biology at the time of diagnosis and in the follow-up of the disease. Magnetic resonance imaging also provides very useful information about the response to treatment.     

Variante interhemisférica media de holoprosencefalia: diagnóstico mediante resonancia magnética fetal

Congenital anomalies of the central nervous system comprise a wide spectrum of malformations associated with a wide variety of genetic syndromes and chromosomal anomalies, and they are among the principal causes of morbidity and mortality in infants. Among these anomalies, holoprosencephaly arises from the complete or partial failure of the brain to divide into the cerebral hemispheres. Imaging tests are fundamental for the prenatal diagnosis of holoprosencephaly; the diagnostic process usually starts with sonography and then the findings are refined with fetal MRI. Radiologists need to be familiar with the possible findings because the prognosis varies.     

La articulación temporomandibular en la artritis idiopática juvenil: lo que el radiólogo debe buscar en la resonancia magnética

The term «juvenile idiopathic arthritis» (JIA) encompasses a group of arthritis of unknown cause with onset before the age of 16 years that last for at least 6 weeks. The prevalence of temporomandibular joint involvement in published series ranges from 17% to 87%. Temporomandibular joint involvement is difficult to detect clinically, so imaging plays a key role in diagnosis and monitoring treatment. MRI is the technique of choice for the study of arthritis of the temporomandibular joint because it is the most sensitive technique for detecting acute synovitis and bone edema. Power Doppler ultrasonography can also detect active synovitis by showing the hypervascularization of the inflamed synovial membrane, but it cannot identify bone edema. This article describes the MRI technique for evaluating the temporomandibular joint in patients with juvenile idiopathic arthritis, defines the parameters to look for, and illustrates the main findings.     

Resonancia magnética de próstata: utilidad de la secuencia de difusión en la detección de isquemia postembolización en pacientes con hiperplasia prostática benigna

ObjectiveTo analyze the usefulness of diffusion magnetic resonance (MR) sequences before and after prostatic artery embolization (PAE) in patients with benign prostatic hyperplasia (BPH).Material and methodsWe analyzed MR studies done before (7-10 days) and after (30 days) PAE in 19 patients with BPH treated with PAE between June 2012 and December 2013. We used 1.5 Tesla scanners with body surface coils. In pre-PAE MR studies, we recorded mean b40 values and minimum (min) and maximum (max) apparent diffusion coefficient (ADC) values. In post-PAE MR studies, we recorded b40, b400, and b1000 values and min, mean, and max ADC values. We compared diffusion behavior/ADC before and after PAE and areas without ischemia. We correlated these with decreased prostatic volume (PV).ResultsWe identified ischemia with contrast in 8 (42.1%) patients. No significant difference was found in mean b40 (p= 0.1650) or in the b40 ratio (p= 0.8868) between patients with ischemia and those without before PAE. Min b40, b40 ratio, and min ADC values differed significantly between ischemic areas and nonischemic areas within patients [p= 0.048 (b40 min and ratio) and p= 0.002 (min ADC)]. No significant correlation was found between the percentage decrease in PV and mean b40 (p= 0.8490) or b40 ratio (p = 0.8573).ConclusionPost-PAE ischemia generates objective changes in diffusion and ADC values that enable ischemic sectors to be differentiated from nonischemic sectors. Future studies should analyze whether it is possible to subjectively differentiate between these areas through the visualization of nonischemic sectors and the feasibility of replacing them with contrast to detect ischemia.     

Valor de la ecografía doppler en la disfunción de los accesos vasculares periféricos para hemodiálisis

ObjectiveThe main objectives of this study were to evaluate the sensitivity and specificity of duplex Doppler ultrasonography in the study of hemodialysis peripheral vascular access dysfunction and to analyze the resistance index and flow in the afferent artery.Material and methodsWe prospectively studied 178 patients with 178 peripheral vascular accesses that were dysfunctional in at least three consecutive hemodialysis sessions. Patients underwent duplex Doppler ultrasonography and clinical and laboratory follow-up for three months (provided angiography findings were negative). We calculated the sensitivity, specificity, predictive values, and coefficients of probability. We studied the morphology of the afferent artery, the arteriovenous anastomosis, and the efferent vein, and we measured the resistance index and the flow of the afferent artery, the diameter of the anastomosis, and the flow and peak systolic velocity in the efferent vein.ResultsThe final sample consisted of 159 patients. The sensitivity, specificity, positive and negative predictive values, and positive and negative coefficients of probability were 0,98 (95% CI: 0,88-1.00), 0,74 (95% CI: 0,66-0,81), 0,96, 0,82, 3.7, and 0,03, respectively. The resistance index was less than 0,5 in 78.5% of the peripheral vascular accesses with normal function and greater than 0,5 in 86.1% of the dysfunctional peripheral vascular accesses. We found aneurysms in 19 of the native peripheral vascular accesses and pseudoaneurysms in 7 of the prosthetic grafts. Inverted flow was seen in 57 peripheral vascular accesses.ConclusionDuplex Doppler ultrasonography is an efficacious method for detecting and characterizing stenosis and thrombosis in peripheral vascular accesses, and it provides information about the morphology and hemodynamics.     

Estimación semiautomática de la densidad mamaria con DM-Scan

ObjectiveTo evaluate the reproducibility of the calculation of breast density with DM-Scan software, which is based on the semiautomatic segmentation of fibroglandular tissue, and to compare it with the reproducibility of estimation by visual inspection.Material and methodsThe study included 655 direct digital mammograms acquired using craniocaudal projections. Three experienced radiologists analyzed the density of the mammograms using DM-Scan, and the inter- and intra-observer agreement between pairs of radiologists for the Boyd and BI-RADS^® scales were calculated using the intraclass correlation coefficient. The Kappa index was used to compare the inter- and intra-observer agreements with those obtained previously for visual inspection in the same set of images.ResultsFor visual inspection, the mean interobserver agreement was 0,876 (95% CI: 0,873-0,879) on the Boyd scale and 0,823 (95% CI: 0,818-0,829) on the BI-RADS^® scale. The mean intraobserver agreement was 0,813 (95% CI: 0,796-0,829) on the Boyd scale and 0,770 (95% CI: 0,742-0,797) on the BI-RADS^® scale. For DM-Scan, the mean inter- and intra-observer agreement was 0,92, considerably higher than the agreement for visual inspection.ConclusionThe semiautomatic calculation of breast density using DM-Scan software is more reliable and reproducible than visual estimation and reduces the subjectivity and variability in determining breast density.