Association of diffusion weighted imaging abnormalities and recurrence in transient global amnesia.

Since the first description of transient global amnesia (TGA) in 1964, its etiology has remained obscure. Reversible diffusion weighted imaging (DWI) hyperintensities in the hippocampus have been found on MRI of some patients with TGA during acute events. The implication of this is not well understood. We identified 47 patients with TGA between November 2004 and November 2009, and enrolled 27 patients with brain MRI within 72 hours of symptom onset for analysis and recorded subsequent relapse or stroke occurrence during follow-up. Nine of the 27 patients had reversible hippocampal punctuate hyperintensities, with complete resolution noted on a second MRI on average 4 months after the initial TGA. Patients with a first relapse (their second TGA attack) had a significantly higher association of DWI hippocampal abnormalities (p=0.03) compared to patients with their first TGA event. None of the 27 patients had a stroke or further relapse during the mean follow-up period of 32.6 months. Thus, patients with recurrent TGA have a significantly higher association of reversible DWI abnormality.

Magnetic Resonance for T-staging of nasopharyngeal carcinoma--the most informative pair of sequences.

OBJECTIVE: To evaluate the most informative pair of sequences in magnetic resonance (MR) for T-staging of nasopharyngeal carcinoma (NPC). METHODS: The MR images of 134 patients with newly diagnosed NPC, from 1996 to 2002, were retrospectively reviewed. All the patients were scanned using 1.5 Tesla MR systems. The images of the nasopharynx were reviewed by two qualified radiologists to determine the positive findings and the T-stage by UICC (6th edition) System, using each sequence separately. The T-stage derived from a single MR sequence was then compared with the T-stage based on the five selected sequences to assess the number and percentage of patients who were being understaged. Therefore, the overall percentage accuracy of each single sequence could be determined. A pair of sequences providing information to achieve almost 100% diagnostic accuracy was then derived. RESULTS: The overall percentage accuracy of five individual sequences of the nasopharynx is as follows: contrast-enhanced (CE) fat suppression (FS) axial T1 (94.8%), CE FS coronal T1 (88.1%), FS axial T2 (85.8%), non-contrast enhanced (NE) axial T1 (78.4%) and non-contrast enhanced (NE) coronal T1 (77.6%). CE FS axial T1 has the best accuracy. All the structures that are missed in CE FS axial T1, which lead to apparent understaging, are appreciated in NE axial T1-weighted images. CONCLUSION: Individual sequences supplement each other in the NPC staging. CE FS axial T1 is the most informative individual sequence. Combination of CE FS axial T1 and NE axial T1 of the nasopharynx provides sufficient information to achieve almost 100% diagnostic accuracy in T-staging; therefore, both should be included in the MR-staging protocol.