Halaweish, Ahmed F

Background Dental hardware produces streak artifacts on computed tomography (CT) images reconstructed with the standard weighted filtered back projection (wFBP) method. Purpose To perform a preliminary evaluation of an iterative metal artifact reduction (IMAR) technique to assess its ability to improve anatomic visualization over wFBP in patients with dental amalgam or other hardware. Material and Methods CT images from patients with dental hardware were reconstructed using wFBP and IMAR software and soft-tissue or bone window/level settings. The anatomy most affected by metal artifacts was identified. Two neuroradiologists determined subjective and objective imaging features, including overall metal artifact score (1 = severe artifacts, 5 = no artifacts), soft-tissue visualization score of the most-compromised structure, and artifact length along the skin surface. CT numbers were used to quantify artifact severity. Results Twenty-four patients were included. IMAR improved overall metal artifact score in 18/24 cases (median =2 ± 0.9 vs. 1 ± 0.6, P < 0.001). Mean CT number in the most-affected anatomical structure significantly improved with IMAR (94.6 vs. 219 HU, P = 0.002) and length of affected skin surface decreased (40.4 mm vs. 118.7 mm, P < 0.001). However, osseous/dental artifactual defects were found in 22/24 cases with IMAR vs. 11/24 with wFBP. Conclusion IMAR software reduced metal artifact both subjectively and objectively and improved visualization of adjacent soft tissues. However, it produced a higher rate of artifactual defects in the teeth and bones than wFBP. Our findings support the use of IMAR as a valuable complement to, but not a replacement for, standard wFBP image reconstruction.

ABSTRACTBACKGROUND AND PURPOSEHypertrophic olivary degeneration (HOD) is an uncommon type of transneuronal degeneration. Case reports and case series described in the literature provide a foundation of our current knowledge of HOD. These reports have described HOD most frequently to be unilateral and occurring in association with lesions in the dentato‐rubro‐olivary pathway. Our purpose was to evaluate the rate of bilateral versus unilateral HOD in a large case series.METHODSA retrospective review was performed to identify patients in which the phrase “hypertrophic olivary degeneration” occurred in the radiology report. A diagnosis of HOD was confirmed on imaging if there was focal hyperintensity on T2‐weighted images confined to either or both inferior olivary nuclei.RESULTSA total of 102 patients had findings consistent with HOD. Of these, 76% had findings bilaterally. In 44%, a lesion could not be identified to explain HOD. Bilateral HOD was common in both lesional and nonlesional group, though more common in the nonlesional group.CONCLUSIONThis study demonstrates that HOD is frequently bilateral. In slightly over 50% of patients with HOD, a lesion can be identified. In just under 50% patients with HOD, a lesion could not be identified and in these cases HOD was present bilaterally in the majority.

ABSTRACTTwo valuable confirmatory MRI findings of acute spinal cord infarct are highlighted and discussed: concomitant vertebral body infarct and ventral cauda equina nerve root enhancement.