Laura Merlini

State-of-the-art MRI techniques in neuroradiology: principles, pitfalls, and clinical applications

This article reviews the most relevant state-of-the-art magnetic resonance (MR) techniques, which are clinically available to investigate brain diseases. MR acquisition techniques addressed include notably diffusion imaging (diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and diffusion kurtosis imaging (DKI)) as well as perfusion imaging (dynamic susceptibility contrast (DSC), arterial spin labeling (ASL), and dynamic contrast enhanced (DCE)). The underlying models used to process these images are described, as well as the theoretic underpinnings of quantitative diffusion and perfusion MR imaging-based methods. The technical requirements and how they may help to understand, classify, or follow-up neurological pathologies are briefly summarized. Techniques, principles, advantages but also intrinsic limitations, typical artifacts, and alternative solutions developed to overcome them are discussed. In this article, we also review routinely available three-dimensional (3D) techniques in neuro MRI, including state-of-the-art and emerging angiography sequences, and briefly introduce more recently proposed 3D quantitative neuro-anatomy sequences, and new technology, such as multi-slice and multi-transmit imaging.

Diffusion-weighted imaging findings in Perthes disease with dynamic gadolinium-enhanced subtracted (DGS) MR correlation: a preliminary study

BackgroundLegg-Calvé-Perthes disease (LCP) is necrosis of the proximal femoral epiphysis of vascular origin. Clinical course and outcome in LCP disease varies considerably between different patients. Earlier prognostic criteria than those offered by conventional radiography are necessary to identify children who require prompt surgical treatment.ObjectiveTo assess the significance of signal alteration on diffusion-weighted MR imaging (DWI MR) in LCP.Materials and methodsTwelve boys with unilateral LCP disease (Catterall grade 2 and 3), at the initial sclerotic stage and early fragmentation phase, underwent dynamic gadolinium-enhanced subtracted (DGS) and DWI MR. For DGS MR, the lateral pillar enhancement was recorded. For DWI imaging, we measured ADC values in the diseased and the unaffected epiphyses and metaphyses. Receiver operating characteristic curves were performed to analyze the performance of DWI in establishing agreement with the results of DGS MR, which is the gold standard for prognosis.ResultsFemoral epiphysis increased diffusivity was observed in the affected hip in all cases. Increased metaphysis diffusivity in the affected side was observed in all cases with absent lateral pillar enhancement at DGS MR.ConclusionDWI seems to be a noninvasive means of distinguishing between Perthes disease with favourable and unfavourable prognosis.

MRI neurography and diffusion tensor imaging of a sciatic perineuroma in a child

Perineuroma, rare in children, presents as a painless mononeuropathy of a major nerve trunk. Resection of the lesion with end-to-end sural nerve grafting appears to be the treatment of choice. This technique is not recommended if the unhealthy segment of nerve is too long or if spinal roots are involved. However, in children, reports of direct MR evaluation of nerve trunks and of the exiting nerve roots are limited. We report a 7-year-old girl with an intramural sciatic nerve perineuroma in whom the diagnosis was made by MRI and confirmed by biopsy. The MR protocol combining 3-D T2-W STIR SPACE, fat-saturated gadolinium-enhanced T1-W images, and diffusion tensor imaging with tractography was a valuable tool for depicting peripheral nerve and roots in order to plan surgical treatment.

Noninflammatory fallopian tube pathology in children

Noninflammatory tubal abnormalities are rare in children and usually not well covered by traditional educational material. The presenting symptoms are nonspecific and are common to many other conditions, so its preoperative diagnosis is rarely made. The purpose of this study was to review the hospital charts and imaging findings in children and sexually inactive adolescents who showed fallopian tube pathology. Understanding of the pertinent findings of previous imaging examinations might assist radiologists in making the correct preoperative diagnosis and increase the likelihood of preserving the fallopian tubes. The clinical entities described in this article include isolated tubal torsion, paratubal cysts, hydrosalpinx, undescended/ectopic fallopian tube, and tubal inguinal hernia.

Orbital tumours and tumour-like lesions: exploring the armamentarium of multiparametric imaging

AbstractAlthough the orbit is a small anatomical space, the wide range of structures present within it are often the site of origin of various tumours and tumour-like conditions, both in adults and children. Cross-sectional imaging is mandatory for the detection, characterization, and mapping of these lesions. This review focuses on multiparametric imaging of orbital tumours. Each tumour is reviewed in relation to its clinical presentation, compartmental location, imaging characteristics, and its histological features. We herein describe orbital tumours as lesions of the globe (retinoblastoma, uveal melanoma), optic nerve sheath complex (meningioma, optic nerve glioma), conal-intraconal compartment (hemangioma), extraconal compartment (dermoid/epidermoid, lacrimal gland tumours, lymphoma, rhabdomysarcoma), and bone and sinus compartment (fibrous dysplasia). Lesions without any typical compartmental localization and those with multi-compartment involvement (veno-lymphatic malformation, plexiform neurofibroma, idiopathic orbital pseudotumour, IgG4 related disease, metastases) are also reviewed. We discuss the role of advanced imaging techniques, such as MR diffusion-weighted imaging (DWI), diffusion tensor imaging, fluoro-2-deoxy-D-glucose positron emission tomography CT (FDG-PET CT), and positron emission tomography MRI (MRI PET) as problem-solving tools in the evaluation of those orbital masses that present with non-specific morphologic imaging findings. Main messages/Teaching points • A compartment-based approach is essential for the diagnosis of orbital tumours. • CT and MRI play a key role in the work-up of orbital tumours. • DWI, PET CT, and MRI PET are complementary tools to solve diagnostic dilemmas. • Awareness of salient imaging pearls and diagnostic pitfalls avoids interpretation errors.

Contribution of acoustic radiation force impulse (ARFI) elastography to the ultrasound diagnosis of biliary atresia.

BackgroundChildren with biliary atresia rapidly develop liver fibrosis secondary to inflammatory destruction of the biliary tract. Noninvasive detection of liver fibrosis in neonatal/infantile cholestasis is an additional criterion for the diagnosis of biliary atresia, leading to prompt surgical exploration.ObjectiveTo assess the value of US with acoustic radiation force impulse (ARFI) elastography to detect biliary atresia in the workup of neonatal/infantile cholestasis.Materials and methodsIn this retrospective study, 20 children with cholestasis suspected of having biliary atresia were investigated by US and ARFI. We evaluated the association between US findings and the diagnosis of biliary atresia and with two scores of liver fibrosis obtained from liver biopsy.ResultsIn univariate analyses, gallbladder size, triangular cord sign, spleen size and ARFI values were found to be associated with biliary atresia, though only the triangular cord sign remained significant when elevated gamma glutamyltransferase (GGT) was included as a predictor. In contrast, spleen size and ARFI correlated with the degree of liver fibrosis on biopsy (r > 0.70, P < 0.001), which remained significant when gamma glutamyltransferase elevation was included as a predictor.ConclusionThe addition of ARFI to a standard abdominal US in the initial workup of the neonate with possible infantile cholestasis can provide reliable information on liver fibrosis and help in the diagnosis of biliary atresia.

Look for the nerves! MR neurography adds essential diagnostic value to routine MRI in pediatric practice: A pictorial overview

PURPOSE This study aimed to assess the feasibility of magnetic resonance (MR) neurography in children, and the potential roles of diffusion-weighted imaging (DWI) and fiber-tracking (FT) techniques. METHODS Five pediatric patients (age range: 6-12 years) underwent magnetic resonance imaging (MRI) for various clinical indications: neurogenic bladder (case 1); persistent hand pain following minor trauma (case 2); progressive atrophy of the lower left extremity muscles (case 3); bilateral hip pain (case 4); and palpable left supraclavicular mass (case 5). All studies were performed using a 1.5-T Avanto MRI scanner (Siemens, Erlangen, Germany). The protocol included 3D T2-weighted STIR and SPACE imaging, T1-weighted fat-saturation post-gadolinium imaging and diffusion tensor imaging (DTI) with tractography. ADC (N×10(-3) mm(2)/s) and FA values were calculated from regions of interest (ROIs) centered on the nerves. Nerve-fiber tracks were calculated using a fourth-order Runge-Kutta algorithm (NeuroD software). RESULTS MR neurography allowed satisfactory visualization of all neural structures, and FA and ADC measurements were feasible. The final diagnoses were Tarlov cysts, median-nerve compression, sciatic perineurioma, Charcot-Marie-Tooth disease and plexiform neurofibroma in a patient with NF-1. DISCUSSION FA and ADC measurements are of little value because of the lack of normal reference values. Nerve-fiber tractography (FT) may be of value in the characterization of tumor pathology, and is also helpful in the planning of surgical treatments. CONCLUSION MR neurography is feasible in pediatric patients. However, a considerable amount of work has yet to be done to establish its role in the clinical management of the wide range of peripheral nerve diseases.

Postnatal management of isolated mild pelvic dilatation detected in antenatal period

Aim: Mild antenatal renal pelvic dilatation (ARPD) revealed by prenatal ultrasound (US) raises the question whether or not screening for vesicoureteral reflux (VUR) is mandatory. The aim of our study was to suggest guidelines for postnatal management of infants with mild ARPD defined as an antero‐posterior (AP) dilatation >5 and <10 mm.

Bilateral Hydrosalpinx in Adolescent Girls with Hirschsprung's Disease: Association of Two Rare Conditions

OBJECTIVE The purpose of our study was to illustrate three cases of bilateral hydrosalpinx in postpubertal girls operated on for Hirschsprungs disease and to discuss the possible cause: iatrogenic or congenital. We identified bilateral hydrosalpinx in three postpubertal sexually inactive girls with Hirschsprungs disease treated, respectively by Duhamel, Soave pull-through, and Martin procedures. No history of surgical complications or pelvic inflammation had been reported. CONCLUSION Hirschsprungs disease is rare in girls and bilateral hydrosalpinx is also extremely uncommon in sexually inactive adolescents. We think there may be a possible common cause: either a postsurgical complication or a congenital defect of the autonomous innervation in the context of a neurocristopathy. Because of the rarity of both conditions, the association is unlikely to be coincidental. The cause of this association is unclear and further studies are required to find its prevalence and to estimate the possible impact on fertility.

Is acute fibrinous and organizing pneumonia the expression of immune dysregulation

Introduction: Acute fibrinous and organizing pneumonia (AFOP) is a recently described histologic pattern of diffuse pulmonary disease. In children, all cases reported to date have been fatal. In this study, we describe the first nonfatal AFOP in a child and review the literature. Description: A 10-year-old boy developed very severe aplastic anemia (VSAA) after being admitted to our hospital with a fulminant hepatic failure of unknown origin. A chest computed tomography scan revealed multiple lung nodules and a biopsy of a pulmonary lesion showed all the signs of AFOP. Infectious workup remained negative. We started immunosuppressive therapy with antithymocyte globulin and cyclosporine to treat VSAA. Subsequent chest computed tomography scans showed a considerable diminution of the lung lesions but the VSAA did not improve until we performed hematopoietic stem cell transplantation 5 months later. Conclusions: Aplastic anemia is associated with a variety of autoimmune syndromes. The sequence of events in our patient suggests that the hepatic failure, AFOP, and the VSAA may all have been part of an autoimmune syndrome. AFOP could be the result of immune dysregulation in this pediatric case with favorable outcome after immunosuppressive therapy and hematopoietic stem cell transplantation.