The presence of macroprolactinaemia does not exclude the possibility of a pituitary adenoma and consequently may not prevent pituitary imaging studies. However, our data demonstrate that all asymptomatic patients who screened positive for macroprolactin had normal pituitary imaging studies. Patient samples showing hyperprolactinaemia should be first tested for macroprolactin, before the patient is submitted to imaging studies. We suggest that imaging studies should be ordered in patients with macroprolactinaemia when indicated by clinically relevant features. As a result, unnecessary anxiety and costly medical procedures may be prevented.

SUMMARY: Limbic encephalitis is far more common than previously thought. It is not always associated with cancer, and it is potentially treatable. Autoantibodies against various neuronal cell antigens may arise independently or in association with cancer and cause autoimmune damage to the limbic system. Neuroimaging plays a key role in the management of patients with suspected limbic encephalitis by supporting diagnosis and excluding differential possibilities. This article describes the main types of autoimmune limbic encephalitis and its mimic disorders, and emphasizes their major imaging features.ABBREVIATIONS: AME ϭ autoimmune-mediated encephalopathy; AMPAR ϭ ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid; CASPR2, contactin-asso-

Trigeminal involvement detected by magnetic resonance imaging (MRI) in multiple sclerosis (MS) patients is usually associated with trigeminal neuralgia (TN) or painless paraesthesia in the trigeminal distribution. Our aim is to review the incidence of trigeminal involvement on MRI in a series of patients with MS at our institution, with further clinical correlation. We reviewed MRI scans of 275 MS patients for the presence of gadolinium enhancement on postcontrast T1-weighted images, anatomical and signal abnormalities on different sequences at the pontine trigeminal root entry zone (REZ) and in the cisternal portion of the nerves. We observed enhancement in the cisternal portion of the nerves and signal abnormalities (with or without enhancement) at the pontine trigeminal REZ in 8 (2.9%) patients, and enhancement was bilateral in 6 (75%) of those. Despite the inflammatory activity, none of them had TN and 3 (37.5%) had only painless paraesthesias in the correspondent V3 distribution. We also found a marked trigeminal hypertrophy in 2 (25%) patients, both with a longer period of disease. Our results confirm a high and clinically silent incidence of trigeminal involvement in MS patients, and suggest a simultaneous role of the central and peripheral type of myelin in trigeminal demyelination.

Perfusion-weighted imaging is a feasible method of reducing the sampling error in the histopathological diagnosis of a presumed LGG, particularly by improving the selection of targets for stereotactic biopsy.

BACKGROUND AND PURPOSE:Patients undergoing parenteral nutrition and those with portosystemic encephalopathy secondary to chronic liver disease and acquired and congenital portosystemic venous shunts frequently present manganese deposition in the basal ganglia, detected by MR imaging as hyperintense areas on T1-weighted sequences. We also observed similar abnormalities in the basal ganglia of patients with chronic renal failure undergoing maintenance hemodialysis. Our aim was to evaluate the pallidal signal intensity on T1-weighted images in a series of patients undergoing hemodialysis, with further evaluation of serum manganese levels and neurologic correlation, comparing them with patients with chronic renal failure without dialytic treatment.

We demonstrated the importance of appropriate MRI sequences for diagnosis of the most frequent brain lesions in TS. Our study reinforces the fact that each sequence has a particular application according to the type of TS lesion. Gd injection might be useful in detecting SGCA; however, the parameters of size and location are also important for a presumptive diagnosis of these tumors.

In addition to findings from conventional magnetic resonance imaging, modern magnetic resonance imaging techniques have provided important information about tumor metabolism, in vivo metabolite formation, water molecule diffusion, microvascular density, and blood-brain barrier permeability, all of which have improved the in vivo diagnostic accuracy of this method in the evaluation of primary central nervous system lymphoma. These nonconventional magnetic resonance techniques are useful in the clinical practice because they enhance conventional magnetic resonance imaging by reinforcing the possibility of a diagnosis and by allowing the early detection of disease recurrence.This report is a review of the most relevant contributions of nonconventional magnetic resonance techniques to the imaging diagnosis of primary central nervous system lymphoma, the differential diagnosis of this disease, and the prognosis of patients. This paper aims to describe a wide range of presentations of primary central nervous system lymphoma, their appearance in imaging, and the differential diagnoses of this disease.

The clinical features of multiple system atrophy (MSA) include four domains: autonomic failure/urinary dysfunction, Parkinsonism, cerebellar ataxia, and corticospinal tract dysfunction. Although the diagnosis of definite MSA requires pathological confirmation, magnetic resonance imaging (MRI) studies have been shown to contribute to the diagnosis of MSA. Although pyramidal tract dysfunction is frequent in MSA patients, signs of pyramidal tract involvement are controversially demonstrated by MRI. We evaluated the pyramidal involvement in 10 patients (7 women) with clinically probable MSA, detecting the presence of spasticity, hyperreflexia, and Babinski sign, as well as demonstrating degeneration of the pyramidal tract and primary motor cortex by MRI in all of them. Our article also discusses key radiological features of this syndrome. In MSA, pyramidal tract involvement seems to be more frequent than previously thought, and the clinicoradiological correlation between pyramidal tract dysfunction and degeneration may contribute to the understanding of the clinical hallmarks of MSA. MRI may also add information regarding the differential diagnosis of this syndrome.