Punctate pattern: A promising imaging marker for the diagnosis of natalizumab-associated PML.

OBJECTIVE: To evaluate the usefulness of the punctate pattern (PP) for the diagnosis and follow-up of patients with progressive multifocal leukoencephalopathy (PML). METHODS: A cohort of 20 consecutive patients with PML, related to natalizumab (NTZ) (n = 14) or not (n = 6), underwent 3T MRI (147 MRI examinations). MRI was available at presymptomatic (n = 9 patients), symptomatic (n = 15), immune reconstitution inflammatory syndrome (IRIS), and chronic stages (n = 20). A pathologic control group of patients without PML (n = 80), with clinically definitive multiple sclerosis or a clinically isolated syndrome suggestive of CNS demyelination, underwent the same MRI protocol. Number and appearance of punctate lesions were assessed by 3 blinded readers using T2-weighted, fluid-attenuated inversion recovery (FLAIR), and postcontrast T1-weighted images. RESULTS: Interobserver agreement was good (κ = 0.79) (0.72-0.87). Of the 20 patients with PML, 18 had PP, including the 14 patients with NTZ-PML; none in the pathologic control group. Of the 9 presymptomatic patients with NTZ-PML, PP was observed in 7 (78% sensitive and 100% specific). Nonenhancing PP on T2-weighted/FLAIR images was detected in 13 patients with PML, exclusively at the presymptomatic or symptomatic stages (including 7 NTZ-PML), whereas enhancing PP occurred in 16 patients with PML, including 13 of the 14 patients with NTZ-PML at the IRIS stage. CONCLUSIONS: PP is a highly specific feature of PML and may be the first imaging feature at the presymptomatic stage with potential implications in patient care. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that a PP on MRI accurately identifies patients with NTZ-PML.

High-pitch, dual-source chest computed tomography angiography without electrocardiographic synchronization: evaluation of cardiac motion artifacts on pulmonary circulation.

PURPOSE: To evaluate the frequency and severity of cardiac motion artifacts on high-pitch, dual-source computed tomography angiograms of the chest. MATERIALS AND METHODS: One hundred consecutive patients underwent a non-electrocardiogram-gated, dual-source chest computed tomography examination with high pitch and high temporal resolution. RESULTS: The mean (±SD) duration of data acquisition was 0.9 (±0.07) seconds and the mean (±SD) heart rate was 78.9 (±15.2) bpm. Cardiac motion artifacts were seen at the level of the pulmonary trunk in 2 patients (2%). Among the 7000 pulmonary arteries analyzed (5 central, 5 lobar, 20 segmental, and 40 subsegmental arteries/patient), pseudofilling defects were depicted at the level of 3 arteries (0.042%), always seen with the concurrent presence of a "double contour" appearance of the vessel walls. Twinkling star artifacts beyond the subsegmental level were seen within 76 segments (76/2000; 3.8% of the examined segments), most commonly in the lingula and left lower lobe. A total of 23 patients (23%) showed at least 1 category of motion artifacts, whereas 77 patients (77%) had motion-free imaging of the pulmonary arteries. CONCLUSIONS: Routine scanning of patients with high pitch and high temporal resolution provides examinations devoid of detrimental cardiac motion artifacts.