Purpose: To present some unusual MR findings in a group of patients from the south‐west of the Dominican Republic suffering from Pantothenate Kinase Associated Neurodegeneration (PKAN).Materials and Methods: Twenty patients and one preclinical case homozygous for the PANK2 mutation, 13 heterozygous gene carriers and 14 healthy volunteers were scanned prospectively using a 3 Tesla system.Results: All patients showed the typical signal reduction within the globus pallidus and the substantia nigra. A surprising finding was the absence of the bright spot (“tiger's eye”) in the medial part of the pallidum in 6 patients, but not in the preclinical case. Both fractional anisotropy (FA) and mean diffusivity (MD) were increased with high significance in the globus pallidus, whereas a reduction of FA in the anterior parts of the internal capsule was accompanied by an elevation of MD.Conclusion: Our findings support the hypothesis that the absence of the “tiger's eye” in PKAN might be secondary, probably caused by an increased accumulation of iron. This could artificially increase FA and MD values and change fiber tracking results. Except for the fronto‐basal tracts, white matter was preserved well. This encouraging finding might support efforts to develop further therapeutic strategies in this devastating dystonia. J. Magn. Reson. Imaging 2012;35:788–794.

Background: Although intracranial Rosai-Dorfman disease is a principally benign lymphohistiocytosis, some patients run a relapsing or progressive course. However, reports about long-term follow-up are extremely rare. Case Description: In two patients, initial tumor resection was incomplete or followed by recurrences over 3 years, which finally subsided after application of chemotherapy, and patients remained tumor-free for more than 7 years thereafter. Conclusion: Up to now there is no agreement on how to treat complicated cases of intracranial Rosai-Dorfman disease; our good experience with adjuvant chemotherapy and long-term follow-up will contribute to treatment planning in complicated cases.

The assessment of shunt reduction after an embolization of an arteriovenous malformation (AVM) or fistula (AVF) from conventional angiography is often difficult and may be subjective. Here we present a completely non-invasive method using magnetic resonance imaging (MRI) to measure shunt reduction. Using pulsed arterial spin labeling (PASL), we determined the relative amount of signal attributed to the shunt over 1.75 s and 6 different slices covering the lesion. This amount of signal from the shunt was related to the total signal from all slices and measured before and after embolization. The method showed a fair agreement between the PASL results and the judgement from conventional angiography. In the case of a total or subtotal shunt occlusion, PASL showed a shunt reduction between 69% and 92%, whereas in minimal shunt reduction as judged by conventional angiography, the ASL result was −6% (indicating slightly increased flow) to 35% in a partially occluded vein of Galen aneurysm. The PASL method proved to be fairly reproducible (up to 2% deviation between three measurements without interventions). On conclusion, PASL is able to reliably measure the amount of shunt reduction achieved by embolization of AVMs and AVFs.