High-resolution DCE-MRI of the pituitary gland using radial k-space acquisition with compressed sensing reconstruction

BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time. MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with goldenangle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time. RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P .005). Time-optimization analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma. CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland imaging

Imaging of trigeminal neuralgia

Trigeminal neuralgia is one of the most frequent neuropathy of the cranial nerves, whose prevalence has been reported between 0.03% and 0.3% in the general population. This condition is a communal manifestation of several possible etiologies. The classical type of trigeminal neuralgia is defined as sudden, usually unilateral, severe, brief, stabbing recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve, with no cause other than a neurovascular compression. Secondary trigeminal neuralgia is the term used to group a large amount of different diseases, which are alike in developing the symptoms of trigeminal neuralgia, due to an insult to the V CN which triggers the complex pathogenesis of pain. These conditions include inflammatory diseases, infections, neoplasms, autoimmune diseases, vascular diseases other than neurovascular conflict, and treatment-related disorders. Generally, the possible mechanisms which lead to the development of neuralgia include nerve distortion/compression by an external mass or damage to the nerve fibers due to an acute or chronic insult. The radiological investigation plays a pivotal role in the diagnosis of trigeminal neuralgia, and MRI constitutes the gold imaging standard in most cases. The trigeminal nerve is a mixed sensory-motor nerve which can be divided anatomically into five segments: brainstem segment, cisternal segment, Meckel’s cave segment, cavernous sinus segment, and extracranial segment. In this paragraph, an anatomy-based imaging approach is proposed to investigate the many causes of trigeminal neuralgia, highlighting the importance of choosing the appropriate sequences and parameters, in the light of a target-suited protocol