Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss.

OBJECTIVE: To compare the findings of magnetic resonance imaging (MRI) with advanced protocols in patients with various types of acute sensorineural hearing loss (ASNHL). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Two hundred eighty-seven patients with ASNHL. INTERVENTIONS: All patients underwent MRI scanning, including heavily T2-weighted three-dimensional fluid-attenuated inversion recovery before and 4 hours after the intravenous administration of gadolinium contrast medium (delayed 3D-FLAIR). A hybrid of the reversed image of the positive endolymph signal and the native image of the perilymph signal image was constructed to visualize the endolymphatic space. RESULTS: The detection rates of abnormal MRI findings vary significantly among different types of ASNHL. A hyperintense signal on delayed 3D-FLAIR was observed in all patients with intralabyrinthine schwannoma or vestibular schwannoma and 20.5% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) but was rarely observed in definite Ménière's disease (MD, 2.6%). In contrast, endolymphatic hydrops (EH) was frequently observed in patients with definite MD (79.5%) but was observed much less frequently in patients with ISSNHL (11.0%). In patients with cochlear MD and ALHL, detection rates of cochlear EH were similar to those with definite MD, whereas detection rates of vestibular EH were significantly lower than in patients with definite MD. CONCLUSIONS: The significantly different detection rates of abnormal MRI findings among various types of ASNHL shed light on the distinct pathophysiology of each disorder. A diagnosis based on MRI findings with advanced protocols may help select treatment strategies and provide prognostic information for patients.

Deep groundwater physicochemical components affecting actinide migration.

To better understand the migration behavior of actinides in deep groundwater (GW), the interactions between doped tracers and deep GW components were investigated. La, Sm, Ho, and U tracers (10 or 100 ppb) were doped into sedimentary rock GW samples collected from 250 to 350 m deep boreholes in the experimental gallery of the Horonobe Underground Research Laboratory (URL), Hokkaido, Japan. To evaluate the effect of GW composition on the chemical speciation of actinides, the same tracers were doped into crystalline rock GW samples collected from 300 to 500 m deep boreholes in the experimental gallery at the Mizunami URL, Gifu Prefecture, Japan. Each GW sample was sequentially filtered through a micro-pore filter (0.2 µm) and ultrafilters with a 10 kDa nominal molecular weight limit. Next, the filtrate solutions were analyzed using inductively coupled plasma-mass spectrometry to determine the concentration of tracers retained in solution during each filtration step, and the used filters were analyzed using time-of-flight secondary ion mass spectrometry element mapping and X-ray absorption fine structure spectroscopy to determine the chemical species of the tracers trapped on each filter. It was determined that lanthanide migration was controlled by the amount of phosphates in the Horonobe GW. Therefore, it was expected that the solubility of minor actinides (MAs), which exhibit a similar chemical behavior to that of lanthanides, would be controlled by the formation of phosphates in sedimentary rock GW. Moreover, the data on the Mizunami GW indicated that a fraction of lanthanides and MAs formed hydroxides and/or hydroxocarbonates.

Fishbone migration to bile ducts after pancreaticoduodenectomy: a case series.

We reviewed six cases suspected of having fish bones in the bile ducts on follow-up CT following pancreaticoduodenectomy. The period from surgery to CT examination in which fishbone migration was first suspected ranged from 282 to 1157 days with a median of 517 days. The fish bone in the bile duct disappeared in five out of six cases on subsequent CT. One case was complicated by hepatolithiasis, and the other five cases showed no biliary complications. In two cases, wandering of fish bones in the jejunal limb was observed on CT images before their migration into the bile ducts. Asymptomatic migration of fish bones to the bile ducts following pancreaticoduodenectomy is not rare, but serious complications can occasionally occur. Indications of intervention may be controversial in asymptomatic cases, but once fish bones are observed in the biliary tree or the jejunal limb, dietary instructions advising not to swallow fish bones may be a good option to prevent complications.

Effect of radiation dose and adaptive statistical iterative reconstruction on image quality of pulmonary computed tomography.

PURPOSE: The purpose of this study was to assess the effects of dose and adaptive statistical iterative reconstruction (ASIR) on image quality of pulmonary computed tomography (CT). MATERIALS AND METHODS: Inflated and fixed porcine lungs were scanned with a 64-slice CT system at 10, 20, 40 and 400 mAs. Using automatic exposure control, 40 mAs was chosen as standard dose. Scan data were reconstructed with filtered back projection (FBP) and ASIR. Image pairs were obtained by factorial combination of images at a selected level. Using a 21-point scale, three experienced radiologists independently rated differences in quality between adjacently displayed paired images for image noise, image sharpness and conspicuity of tiny nodules. A subjective quality score (SQS) for each image was computed based on Anderson's functional measurement theory. The standard deviation was recorded as a quantitative noise measurement. RESULTS: At all doses examined, SQSs improved with ASIR for all evaluation items. No significant differences were noted between the SQSs for 40%-ASIR images obtained at 20 mAs and those for FBP images at 40 mAs. CONCLUSION: Compared to the FBP algorithm, ASIR for lung CT can enable an approximately 50% dose reduction from the standard dose while preserving visualization of small structures.