Susceptibility weighted imaging in the evaluation of movement disorders.

Movement disorders are neurodegenerative disorders associated with abnormalities of brain iron deposition. In this presentation, we aim to describe the role of susceptibility weighted imaging (SWI) in the imaging of patients with movement disorders and differentiate between the various disorders. SWI is a high-resolution, fully velocity-encoded gradient-echo magnetic resonance imaging (MRI) sequence that consists of using both magnitude and phase information. We describe briefly the physics behind this sequence and the post-processing techniques used. The anatomy of the midbrain and basal ganglia in normal subjects on SWI is covered. A number of neurodegenerative disorders are associated with abnormal iron deposition, which can be detected due to the susceptibility effects.

Suboptimal contrast opacification of dynamic head and neck MR angiography due to venous stasis and reflux: technical considerations for optimization.

BACKGROUND AND PURPOSE: Contrast-enhanced head and neck MRA may be degraded by venous stasis and reflux of contrast into the jugular veins. The purpose of this study was to evaluate the relationship between venous stasis and reflux and the side of injection and other causal factors. MATERIALS AND METHODS: One hundred twenty-six consecutive patients (94 males and 32 females) who underwent contrast-enhanced MRA were evaluated for the side of contrast injection (left, n = 65; right, n = 61), hypertension, and cardiac disease. The retrosternal space was measured in all patients with left-arm injections. RESULTS: Eight patients (6.34%) had reflux into the jugular veins. The difference in the mean ages of patients with and without reflux was not significant (P = .069). There was a significant difference in the incidence of systemic hypertension in patients with (77.78%) and without reflux (23.73%; P = .007). There was no significant difference in the incidence of cardiac disease in patients with and without reflux (P = .323). The difference in the side of injection in patients with and without reflux (P = .005) and the difference in the mean retrosternal distance in the patients with left-arm injection with (7.2 mm) and without reflux (12.1 mm) were statistically significant (P < .001). CONCLUSIONS: Compression of the left brachiocephalic vein between the sternum and a tortuous aorta and proximal vessels may lead to venous reflux that can degrade the quality of contrast-enhanced MRA. Our study suggests that venous reflux can be avoided by routinely injecting right-sided veins.