Diehn, Felix E

Background SynthesiZed Improved Resolution and Concurrent nOise reductioN (ZIRCON) is a multi-kernel synthesis method that creates a single series of thin-slice computed tomography (CT) images displaying low noise and high spatial resolution, increasing reader efficiency and minimizing partial volume averaging. Purpose To compare the diagnostic performance of a single set of ZIRCON images to two routine clinical image series using conventional CT head and bone reconstruction kernels for diagnosing intracranial findings and fractures in patients with trauma or suspected acute neurologic deficit. Material and Methods In total, 50 patients underwent clinically indicated head CT in the ER (15 normal, 35 abnormal cases). A non-reader neuroradiologist established the reference standard. Three neuroradiologists reviewed two routine clinical series (head and bone kernels) and a single ZIRCON series, detecting intracranial findings or fractures and rating confidence (0–100). Sensitivity, specificity, and jackknife free-response receiver operating characteristic (JAFROC) figure of merit (FOM) were compared (limit of non-inferiority: −0.10). Results ZIRCON and conventional images demonstrated comparable performance for fractures (sensitivity: 51.5% vs. 54.5%; specificity: 40.2% vs. 34.2%) and intracranial findings (sensitivity: 88.2% vs. 91.4%; specificity: 77.2% vs. 73.7%).The estimated difference of JAFROC FOM demonstrated ZIRCON non-inferiority for acute pathologies overall (0.003 [95% CI=−0.051–0.057]) and fractures (0.048 [95% CI=−0.050–0.145]) but not for intracranial findings alone (−0.024 [95% CI=−0.100–0.052]). Conclusion Thin-slice, low noise, and high spatial resolution images can be created to display intracranial findings and fractures replacing multiple images series in head CT with similar performance. Future studies in more patients and further algorithmic development are warranted.

Standard clinical protocols require hearing protection during magnetic resonance imaging (MRI) for patient safety. This investigation prospectively evaluated the auditory function impact of acoustic noise exposure during a 3.0T MRI in healthy adults. Twenty-nine participants with normal hearing underwent a comprehensive audiologic assessment before and immediately following a clinically indicated head MRI. Appropriate hearing protection with earplugs (and pads) was used per standard of practice. To characterize noise hazards, current sound monitoring tools were used to measure levels of pulse sequences measured. A third audiologic test was performed if a significant threshold shift (STS) was identified at the second test, within 30 days post MRI. Some sequences produced high levels (up to 114.5 dBA; 129 dB peak SPL) that required hearing protection but did not exceed 100% daily noise dose. One participant exhibited an STS in the frequency region most highly associated with noise-induced hearing loss. No participants experienced OSHA-defined STS in either ear. Overall, OAE measures did not show evidence of changes in cochlear function after MRI. In conclusion, hearing threshold shifts associated with hearing loss or OAE level shifts reflecting underlying cochlear damage were not detected in any of the 3.0T MRI study participants who used the current recommended hearing protection.

Abstract Objective Ensuring medication delivery to the epidural space is crucial for effective transforaminal epidural steroid injections. Epidural needle placement is determined by injecting a small amount of contrast at the final needle position. The purpose of this study is to illustrate the appearance of contrast flow in the retrodural retroligamentous space of Okada during computed tomography– and fluoroscopy-guided cervical and lumbar transforaminal epidural steroid injections. Design This retrospective study will use a series of cases to demonstrate contrast within the space of Okada during epidural transforaminal steroid injections. Setting Tertiary medical center. Subjects Study subjects are adult patients who underwent transforaminal epidural steroid injection at our institution. Methods Cases were identified through the use of a search engine of existing radiology reports at our institution. Epidural steroid injection procedural reports were searched for the terms “Okada” and “retrodural space.” Images from the procedure were reviewed by the authors (all proceduralists with dedicated training in spinal injections) to confirm the presence of contrast within the space of Okada. Results This case series illustrates six examples of contrast injection into the retrodural space of Okada during cervical and lumbar transforaminal epidural steroid injections. Conclusions Contrast uptake in the retrodural space of Okada may be seen during transforaminal epidural injections. Although relatively uncommon, it is likely underrecognized. It is extremely important that providers who perform transforaminal epidural steroid injections be familiar with this non-epidural contrast flow pattern so they can adjust needle positioning to deliver steroid to the epidural space.

Case: A 41-year-old man sustained occipitocervical dislocation (OCD) and atlantoaxial dislocation (AAD) injuries in a motor vehicle collision. These injuries were treated nonoperatively with a hard cervical collar and activity restrictions with an excellent result at 4-year follow-up. Conclusion: OCD and AAD injuries require prompt diagnosis and immobilization. Standard of care for coexisting injuries is occipitocervical fusion; however, some patients have coexisting injuries which may prevent operative treatment. These polytrauma patients require a creative nonoperative approach with close follow-up to avoid neurologic decline.

ABSTRACTBACKGROUND AND PURPOSEThere is a relative paucity of radiology literature on spinal cord cavernous malformations (SCMs). We hypothesized that the classic MRI features of cavernous malformations are not highly prevalent. The purpose was to review MR imaging findings of SCMs with a focus on prevalence of hemorrhagic features, including adjacent intramedullary hemorrhage at initial presentation.METHODSIn this single‐institution study, 78 SCMs in 76 patients diagnosed on imaging/pathology were retrospectively evaluated for size, location, cord expansion, exophytic component, popcorn morphology, signal characteristics, including T1 weighted (T1w) and T2w rims, blood‐fluid levels, and adjacent intramedullary hemorrhage. Intramedullary hemorrhage was defined as centrally and/or eccentrically located linear or flame shaped non‐edematous signal abnormality extending longitudinally away from SCMs, distinct from lesional rim.RESULTSSixty‐three percent (49/78) of SCMs measured <1 cm in length, 78% (61/78) extended to the cord surface, 65% (51/78) were expansile, and 32% (25/78) were exophytic. Popcorn morphology was seen in 15% (12/78) on T1w and 22% (17/78) on T2w. Internal blood‐fluid levels were evident in 4% (3/78). Sixty‐nine percent (54/78) showed T2w hypointense rims; the T2w rim was complete/near‐complete in 37% (29/78). A rim on T1w was visible in 49% (38/78); this was hyperintense in 58% (22/38). Adjacent intramedullary hemorrhage was seen in 45/78 (58%), was most commonly bidirectional in 67% (30/45) and eccentric in 68% (30/44). Cord edema was seen in 22% (17/78); 53% (9/17) also demonstrated intramedullary hemorrhage with edema.CONCLUSIONSThe classically described popcorn morphology, internal blood‐fluid levels, and complete/near‐complete T2w hypointense rims are often absent on MRIs in SCMs. Adjacent intramedullary hemorrhage is frequently present, often eccentric and bidirectional.

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.