The purpose of this study was to evaluate the value of MRI in studying optic pathway tumours associated with neurofibromatosis, and to look for potentially helpful criteria for the management of such lesions. This retrospective study included 14 children with neurofibromatosis type 1 (NF-1) as well as a lesion of the optic pathway. Clinical data and MRI findings were analysed with regard to location, structure and course of the tumours, and were compared with 13 optic pathway tumours in patients without NF-1. The median age of onset was 4.1 years. 11 patients with NF-1 were asymptomatic. In the NF-1 group, the optic nerves were involved in 10 cases without a cystic component at the time of diagnosis. In the non-NF-1 group, the tumour was located in the chiasma in 11 cases; 12 cases had a cystic component. 10 of the NF-1 group had no tumour progression over an average follow-up of 3.2 years without treatment. These findings suggest that optic astrocytomas in association with NF-1 are distinct lesions from isolated optic gliomas. In NF-1, most such tumours show only slight progression, and may correspond to perineural gliomatosis rather than a true pilocytic astrocytoma. Among NF-1 patients, initial MRI provides no prognostic criteria in children who subsequently show tumour progression. Nevertheless, MRI can be useful in establishing the diagnosis of NF-1 and can serve as a baseline study.
Dilatation of the collecting system is a classical phenomenon during pregnancy, due to hormonal and extrinsic compressive factors. Imaging has to differentiate a physiological dilatation and a pathological obstruction due to urolithiasis. Presently, sonography, using both, B-mode and color Doppler, has the potential to demonstrate the physiological compression of ureters at the level of the pelvic brim. A pathological obstruction is considered either when a stone is detected above the usual site of compression or when the ureter appears dilated beyond. Color Doppler helps in localizing the site of ureteral compression against the vessels and in differentiating ureters from veins. Magnetic resonance urography, with strongly T2-weighted sequences, also may show the site and type of obstruction without contrast agent administration. These two non-radiating techniques make it possible to avoid the use of X-rays in most cases for management of these patients. The type of treatment is based mostly on the level of pain and the presence or absence of stone.
Cytomegalovirus is the most common cause of congenital viral infection. In utero this infection is usually suspected on the basis of ultrasound findings. We present a case in which routine ultrasound examination demonstrated a decrease in fetal cephalic dimensions at 32 weeks’ gestation in an asymptomatic patient. Transvaginal ultrasound revealed echogenic vessels in the thalami and lesions in the subependymal region. Suspected diagnosis of fetal cytomegalovirus infection was confirmed by positive titers of anti-cytomegalovirus-IgM antibodies in fetal blood and amniotic-fluid PCR studies. Fetal cerebral MRI demonstrated parenchymal atrophy and polymicrogyria. The parents decided to terminate the pregnancy, and necropsy confirmed the diagnosis. Suspicion of CMV fetal infection should prompt transvaginal ultrasound and fetal brain MRI.
Infection during pregnancy is common and the developing fetal brain is vulnerable to vertical transmission due to immaturity of the fetal immune system. Infection is a major cause of multiple organ abnormalities, including the neuraxis, due to the neurotropism of the infectious agents. This review sets out to give an overview of fetal infection, review the general principles of the nature and timing of the infectious insult with respect to outcomes, review the neuroimaging of infection by ultrasound and magnetic resonance imaging (MRI), and review the various pathogens involved, including the two most common, cytomegalovirus (CMV) and Toxoplasma, and also other common viral and nonviral infections.
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