Imaging of trochlear nerve schwannomas: a case series and systematic review of the literature.

Purpose Trochlear nerve schwannomas are rare tumors. So far, only 121 cases have been published. We present four new cases, discuss the imaging characteristics and summarize all previously published cases through a systematic review.Methods Four cases, all treated in AZ Sint-Jan Hospital Brugge-Oostende (Belgium), were collected, including their demographic, clinical and radiological data. All MR imaging was performed with the three-dimensional fluid-attenuated inversion recovery (3D-FLAIR), turbo spin echo T1 high-resolution (TSE T1 HR), three-dimensional balanced fast-field echo (3D b-FFE) and three-dimensional T1 black blood (3D T1 black blood) sequence. We compared our findings with the present literature through a systematic literature review in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.Results Screening with routine unenhanced 3D-FLAIR imaging could identify all schwannomas as hyperintense lesions on the course of the trochlear nerve. The use of 3D T1 black blood sequences was superior in depicting the lesions, while high-resolution 3D b-FFE images enabled us to visualize the anatomic boundaries of the lesions in detail. Most trochlear schwannomas are located in the ambient cistern, at or just below the free edge of the tentorium.Conclusion The majority of trochlear nerve schwannomas are located cisternal and display variable enhancement on contrast administration. 3D-FLAIR imaging is superior in detecting these lesions. Comparison with data collected from previous cases demonstrates the importance of early diagnosis and treatment. Generally, patients with trochlear nerve schwannomas have a good prognosis.

Rim lesions in MS at 3T: clinical correlation and possible radiological alternatives for daily practice at lower field strength.

BACKGROUND AND PURPOSE: Paramagnetic rim lesions (PRLs) have been described as an imaging feature specific to multiple sclerosis (MS) using high-field strength phase-sensitive MR imaging. These lesions are suggested to reflect chronic active inflammation associated with greater disease severity and a more rapid disability progression. The aim of our study is to investigate the relationship between PRLs, clinical parameters, other radiological findings and disease progression. MATERIAL AND METHODS: This cross-sectional study included MS patients treated with teriflunomide, fingolimod, natalizumab or ocrelizumab for at least 2 years. PRLs seen at 3T MRI were analysed and correlated with clinical data and radiological progression, defined as an increase of the T2/FLAIR-lesion load during therapy. In the search for alternatives for these PRLs, we defined two additional radiological markers: 'FLAIR-bullet lesions', and on post-contrast black-blood (BB) images, 'BB-bullet lesions'. RESULTS: We included 84 MS patients of whom 27 (32 %) had at least 1 PRL. PRLs were associated with radiological progression under therapy (p=0.039) and higher clinical disability scores, although only significant for 9-Hole Peg Test (p=0.023). Patients with FLAIR-bullet or BB-bullet lesions at 3T MRI had a higher chance of PRL (p<0.001) with a likelihood ratio of 13.2 for FLAIR-bullets and 12.6 for BB-bullet lesions, thanks to the high negative predictive value of respectively 83 % and 90 %. CONCLUSION: PRLs are associated with an increase of T2/FLAIR-lesion load under therapy and unfavourable clinical outcome. Our newly defined 'bullet lesions' are associated with PRLs and might be an interesting MRI marker for centres without access to high-field SWI images.

Correlation of semi-quantitative findings of endolymphatic hydrops in MRI with the audiometric findings in patients with Meniere's disease.

Purpose: To investigate the correlation between vestibular hydrops (VH), cochlearhydrops (CH), vestibular aqueduct non-visibility (VANV), and visually increased perilymphatic enhancement (VIPE) with the findings of pure-tone audiometry (PTA) in Meniere's disease (MD) patients. Methods: In this cross-sectional study, 53 ears belonging to 48 patients were divided into two groups and evaluated. In group "MD patients," there were 24 ears of 19 patients diagnosed with the definite MD (14 patients with unilateral and 5 patients withbilateral involvements). The "control group" consisted of 29 non-symptomatic ears belonging to patients diagnosed with unilateral sudden sensory-neural hearing loss or unilateral schwannoma. All the patients underwent 2 sessions of temporal bone MRI using the same 3T system: an unenhanced axial T1, T2, and 3D-FLAIR MRI, an intravenous gadolinium-enhanced axial T1 fat-sat, and 4 h after the injection, an axial 3D-T2 cube and 3D-FLAIR session. VH, CH, VANV, and VIPE were assessed. Subsequently, the correlation between EH indices and PTA findings (in three frequency domains of low, middle, and high) were evaluated, and the predictive value of MRI was calculated. Results: VH was significantly correlated with the hearing threshold in the low, middle, and high-frequency domains. CH was also correlated with the hearing threshold in the low and middle domains. Contrarily, VIPE was not associated with hearing thresholds, and VANV was only correlated with the hearing threshold in low frequencies. Conclusion: The grade of VH, CH, and VANV were significantly correlated with the hearing thresholds in PTA.

Comparison between 3D SPACE FLAIR and 3D TSE FLAIR in Menière's disease.

PURPOSE: Heavily T2-weighted 3D FLAIR (hT2w-3D-FLAIR) sequence with constant flip angle (CFA) has been reported as being more sensitive to low concentrations of gadolinium (Gd) enabling endolymphatic hydrops (EH) visualization. The purpose of this study was to compare signal-to-noise (SNR) ratio, detection rate of EH, and increased perilymphatic enhancement (PE) as well as diagnostic accuracy in diagnosing definite Menière's disease (MD), using 3D-SPACE FLAIR versus conventional 3D-TSE FLAIR. METHODS: This retrospective study included 29 definite MD patients who underwent a 4-h delayed intravenous (IV) Gd-enhanced 3D-TSE FLAIR and 3D-SPACE FLAIR MRI between February 2019 and February 2020. MR images were qualitatively and quantitatively analyzed twice by 2 experienced head and neck radiologists. Qualitative assessment included grading of cochlear and vestibular EH and visual comparison of PE. Quantitative assessment of PE was performed by placing a region of interest (ROI) and ratio calculation in the basal turn of the cochlea and the brainstem. RESULTS: The intra- and inter-reader reliability for grading of EH and PE was excellent (0.7 < kappa < 0.9) for 3D-SPACE FLAIR and exceeded the values for 3D-TSE FLAIR (0.5 < kappa < 0.9) The combination of EH and visual assessment of PE has the highest diagnostic accuracy in diagnosing definite MD on 3D-SPACE FLAIR with a sensitivity of 0.91 and a specificity of 0.98 resulting in a sensitivity raise of 6% compared to 3D-TSE FLAIR. CONCLUSION: Four-hour delayed IV Gd-enhanced 3D-SPACE FLAIR sequence has a higher sensitivity and reproducibility than 3D-TSE FLAIR for the visualization of EH and increased PE in definite MD patients.

Radiological Follow-up After the Bony Obliteration Tympanoplasty in Detecting Residual Cholesteatoma: Towards an Optimal Postoperative MR Imaging Protocol.

INTRODUCTION AND AIM: There is no consensus in literature on the most optimal follow-up imaging protocol for non-echoplanar diffusion-weighted magnetic resonance imaging (non-EP DW MRI) after the canal wall-up bony obliteration tympanoplasty. Clearly, no residual cholesteatoma should be missed but on the other hand, unnecessary MR controls should be avoided. The aim of this study is to evaluate the postoperative results of non-EP DW MRI after canal wall-up bony obliteration tympanoplasty surgery at our Institute and to propose an optimal postoperative MR imaging scheme based on our data. MATERIAL AND METHODS: Retrospective cohort study; all 271 patients who underwent the bony obliteration tympanoplasty between January 2010 and January 2016 with follow-up at our Institute were included. A postoperative MR imaging was systematically performed at 1 year after surgery and repeated at either 5 or both 3 and 5 years after surgery, based on the preferences of the surgeon. Variables of interest were retrieved from electronic patient records. RESULTS: The median follow-up time was 60 months (inter-quartile range 56-62 mo). Two hundred seventy-one patients (100%) received a 1-year MRI, 107 (39%) a 3-year MRI, and 216 (79.7%%) a 5-year MRI. Residual cholesteatoma was found in nine cases (3.3%), corresponding with an estimated residual rate at 5 years follow-up of 3.7% when using Kaplan-Meier analysis. Of these nine cases, six cases of residual cholesteatoma (66.7%) were detected at the 1-year MRI (12-14 mo postsurgery), two cases (22.2%) at the 3-year MRI (35-39 mo postsurgery), and one case (11.1%) at the 5-year MRI (51 mo postsurgery, in this patient no 3-year MRI was performed). An uncertain MRI result was found in 15 cases, presenting as relatively hyperintense lesions. However, subsequent follow-up scans did not show persistent evidence for residual disease in 14 of these 15 cases. CONCLUSIONS: A postoperative MRI scan after 1 and 5 years is essential to detect early and late residual cholesteatoma. In our cohort, 22.2% of residual cases were detected at the 3-year MRI. However, this percentage could potentially have been higher when all patients would have received a 3-year MRI. Therefore, in order to detect residual disease as soon as possible, we propose to perform an MRI scan at 1, 3, and 5 years after the bony obliteration tympanoplasty. In cases with an unclear MR result, we suggest a repeat MRI after 12 months.

Smoldering lesions in MS: if you like it then you should put a rim on it.

PURPOSE: In multiple sclerosis (MS), chronic active/smoldering white matter lesions presenting with hypointense rims on susceptibility-weighted imaging (SWI) of the brain have been recognized as an important radiological feature. The aim of this work was to study the prevalence of paramagnetic rim lesions (RLs) in MS patients in a clinical setting and to assess differences in demographic and clinical variables regarding the presence of RLs. METHODS: All 3 T brain magnetic resonance (MR) studies performed in MS patients between July 2020 and January 2021 were reviewed. In all patients, RLs were assessed on three-dimensional (3D) SWI images and the T2 FLAIR lesion load volume was assessed. Demographic, laboratory (oligoclonal bands in CSF), and clinical data, including functional status with Expanded Disability Status Scale (EDSS), were retrieved from the clinical files. RESULTS: Of the 192 patients, 113 (59%) presented with at least 1 RL. In the RL-positive group, the mean RL count was 4.81 ranging from 1 to 37. There was no significant difference in the number of RLs between the different types of MS (p = 0.858). Regarding the presence of RLs, there were no significant differences based on gender (p = 0.083), disease duration (p = 0.520), treatment regime (p = 0.326), EDSS score (p = 0.103), and the associated T2 FLAIR lesion load volume. CONCLUSION: SWI RLs were frequently detected in our cohort regardless of the MS type, T2 FLAIR lesion load volume, demographic features, disease duration, or clinical score. Our results suggest that RLs are not associated with more severe forms of the disease. Today, RLs can be seen on 3 T 3D SWI, although this is not a clinical standard sequence yet. Therefore, it should be considered an additional helpful MR sequence in the diagnostic workup of MS, although more studies are warranted to establish the role of RLs as prognostic markers.

Alemtuzumab in multiple sclerosis: A retrospective analysis of occult hemorrhagic magnetic resonance imaging lesions and risk factors.

BACKGROUND AND PURPOSE: Alemtuzumab, a monoclonal CD52 antibody, is a high-efficacy disease-modifying-therapy in relapsing-remitting multiple sclerosis (RRMS). Recently, intracerebral hemorrhage (ICH) was reported as a possible treatment-related adverse event. Arterial hypertension during infusion was suggested as a potential cause, although platelet or endothelial dysfunction may also contribute. This study aimed to screen for occult hemorrhagic cerebral lesions after alemtuzumab treatment and to further elucidate risk factors. METHODS: We included 30 RRMS patients who received alemtuzumab treatment at Ghent University Hospital or Sint-Jan Bruges Hospital. Retrospective data concerning vital signs, adverse effects and thrombocyte levels during treatment were collected. The occurrence of occult intracranial hemorrhagic lesions was assessed by magnetic resonance imaging with susceptibility-weighted imaging (SWI). RESULTS: The mean (standard deviation [SD]) systolic blood pressure (SBP) during the morning, afternoon and evening was 120 (3.38) mmHg during first administration and 114 (4.40) mmHg during second administration (N = 13). There was no significant increase in SBP when comparing morning, afternoon and evening per day, nor was there a significant difference in daily mean SBP between consecutive administration days. Thrombocyte count during treatment cycles ranged between 107 × 109 /L and 398 × 109 /L, with a mean (SD) absolute reduction of 59.3 × 109 /L (50.65) or a mean (SD) relative reduction of 25.0 (12.84)% (N = 20). No patient had ICH, nor did SWI show any cerebral microbleeds or other hemorrhagic lesions post-treatment (N = 23). CONCLUSIONS: In our patient population, alemtuzumab treatment was not associated with arterial hypertension, ICH or occult microbleeds. Possible differences in administration regimen (ambulatory vs. in-hospital setting) and patient population (cardiovascular risk) might explain an increased risk in different populations.

The Diagnostic Value of Magnetic Resonance Imaging in Posttraumatic Trigeminal Neuropathic Pain.

AIMS: To evaluate the diagnostic value of non-nerve-selective MRI sequences in posttraumatic trigeminal neuropathic pain (PTNP). METHODS: This study retrospectively analyzed all MRI protocols performed between February 2, 2012 and June 20, 2018 commissioned by the Department of Oral and Maxillofacial Surgery, University Hospitals Leuven. Demographic, clinical, and radiologic data were extracted from the records of patients with an MRI in the context of PTNP. A contingency table was constructed based on the opinions of the treating physician and the radiologist who initially evaluated the MRI. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. RESULTS: The sample consisted of 27 women (65.9%) and 14 men (34.1%). The sensitivity and negative predictive value of MRI in PTNP were 0.18 and 0.77, respectively. Artifacts interfered with visualization of a possible cause of the trigeminal pain in 24.4% of MRIs. Almost all artifacts (90%) were caused by metal debris originating from the causal procedure or posttraumatic surgeries. MRI resulted in changed management for PTNP patients only once. CONCLUSION: The diagnostic value of non-nerve-selective MRI sequences for PTNP is low and has little impact on clinical management. Therefore, there is a need for dedicated sequences with high resolution and low artifact susceptibility for visualizing the posttraumatic injuries of the trigeminal branches.

The relationship between cochleovestibular function tests and endolymphatic hydrops grading on MRI in patients with Menière's disease.

PURPOSE: In this retrospective study the relationship between cochleovestibular function and a magnetic resonance imaging (MRI-) based classification system of endolymphatic hydrops was investigated. METHODS: Seventy-eight patients with unilateral definite Menière's disease who underwent MRI were included. The parameters of Pure Tone Audiometry (PTA), caloric irrigation test, cervical vestibular evoked myogenic potentials, and video Head Impulse Test were compared between the grades of endolymphatic hydrops (EH) and perilymphatic enhancement (PE) on MRI. RESULTS: The low-frequency PTA was significantly different between cochlear EH grades I and II (p = 0.036; Grade I: mean (Standard Deviation, SD) = 51 decibel Hearing Level (dB HL) (18 dB HL); Grade II: mean (SD) = 60 dB HL (16 dB HL)), and vestibular EH grades 0 and III (p = 0.018; Grade 0: mean (SD) = 43 dB HL (21 dB HL); Grade III: mean = 60 dB HL (10 dB HL)). The ipsilateral caloric sum of ears with vestibular EH grade I (n = 6) was increased with regards to vestibular EH grades 0 (p = 0.001), II (p < 0.001), and III (p < 0.001) (Grade 0: mean (SD) = 24°/s (15°/s); Grade I: mean (SD) = 47°/s (11°/s); Grade II: mean (SD) = 21°/s (13°/s); Grade III: mean (SD) = 16°/s (8°/s)). CONCLUSION: According to these results we can conclude that only the highest grades of cochlear and vestibular EH seem to be associated with decreased cochleovestibular functioning.

Labyrinthine enhancement on 3D black blood MR images of the brain as an imaging biomarker for cisplatin ototoxicity in (lung) cancer patients.

PURPOSE: Cancer patients treated with platinum-based chemotherapy can present with ototoxicity symptoms. The purpose of this work is to report the imaging features related to cisplatin ototoxicity. METHODS: Between December 2015 and March 2019, a cohort of 96 consecutive patients with lung cancer was selected. Only patients who received cisplatin chemotherapy and underwent an imaging protocol consisting of a Gd-enhanced 3D-BB and 3D-T1W sequence, as well as T2W sequence to exclude metastases, were included. Labyrinthine enhancement was assessed, and all findings regarding the auditory and vestibular function were retrieved from the clinical files. RESULTS: Twenty-one patients met the inclusion criteria. The Gd-enhanced 3D-BB images were used to divide them into the labyrinth enhancement group (LEG) and the labyrinth non-enhancement group (LNEG). None of these patients demonstrated enhancing regions on the 3D-T1W images. The labyrinthine fluid remained high on the T2 images in all patients, excluding metastases. The LEG consisted of 6 patients. The cochlea and semicircular canals were the most frequently affected regions. All the LEG patients that presented with hearing loss (4/6) had cochlear enhancement. Patients with normal hearing had no cochlear enhancement. Five patients (5/6) showed vestibular enhancement. Four of these patients had vestibular symptoms. CONCLUSION: Labyrinthine enhancement as an imaging feature related to cisplatin ototoxicity is unreported. This study demonstrates a correlation between hearing loss and cochlear enhancement and also between vestibular impairment and vestibular/semicircular enhancement on 3D-BB images, which remained invisible on the 3D-T1W images. The labyrinthine enhancement on 3D-BB images in the presence of normal signal intensity of the intralabyrinthine fluid can be used as an imaging biomarker for cisplatin toxicity in daily clinical practice and should not be mistaken for intralabyrinthine metastases.

Facial and Dental Trauma.

Dental and facial trauma are very common in a daily routine radiology practice. Knowledge of the functional anatomy of the mandibulofacial and maxillofacial regions forms the cornerstone of a thorough full radiologic evaluation of the patient with a dental and/or facial trauma. Cone beam computed tomography and multidetector computed tomography are currently considered the imaging modalities of choice. There are several patterns and classification systems for the various subtypes of mandibulofacial and maxillofacial fractures. They are discussed separately in this article with special attention to the types of dental trauma and orbital trauma.

Temporomandibular Joint Disorders: A Pictorial Review.

Temporomandibular joint (TMJ) disorders are commonly encountered in the general population but often ignored or unrecognized. The detection and characterization of lesions has drastically improved over the years due to technological advances in cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI). However, adequate knowledge of the normal imaging appearance on different imaging modalities as well as the broad variety of pathology is required to provide a proper radiologic assessment. This pictorial review focuses on TMJ pathology and its appearance on CBCT and MRI. A short overview of the technical aspects and normal anatomy are provided to round out this complete summary on the subject.

Cone beam computed tomography in dentomaxillofacial radiology: a two-decade overview.

OBJECTIVES: The aim of this study was to evaluate and summarise features of currently and formerly available cone beam CT (CBCT) devices from 1996 to 2019. Additionally, a recommendation for standardised reporting of CBCT characteristics was provided. METHODS AND MATERIALS: Information about the features of all available CBCT devices was obtained from the manufacturers' available data. Moreover, site visits to newly developed CBCT machines' manufacturers were performed in order to obtain relevant information. RESULTS: A total of 279 CBCT models from 47 manufacturers located in 12 countries (Brazil, China, Denmark, Finland, France, Germany, Italy, Japan, Republic of Korea, Slovakia, Thailand, and USA) could be listed. Overall, wide variations in CBCT features and technical specifications were identified. CONCLUSIONS: CBCT in dentomaxillofacial radiology is a generic term applicable to a broad range of CBCT machines and features. Experimental outcomes and literature statements regarding radiation doses, imaging performance and diagnostic applicability of dental CBCT cannot be simply transferred from one CBCT model to another considering a wide variation in technical characteristics and clinical diagnostic performance. The information tabulated in the present study will be later provided on the International Association of DentoMaxilloFacial Radiology website (www.iadmfr.one).

Cochlear Erosion due to a Facial Nerve Schwannoma.

Facial nerve schwannomas are rare benign neoplasms. We report a case of a 60-year-old woman who initially presented with vestibular complaints. Magnetic resonance imaging (MRI) revealed a facial nerve schwannoma centered on the right geniculate ganglion extending in the labyrinthine segment. The patient consulted again after 2 months because she developed a sudden and severe right-sided sensorineural hearing loss. MRI showed no progression or pathological enhancement in the membranous labyrinth. A cone beam computed tomography (CT) of the temporal bone was performed and revealed a large erosion at the region of the geniculate ganglion in open communication with the middle turn of the cochlea. This case report demonstrates the importance of CT in facial nerve schwannomas for evaluating the impact on the surrounding structures.

The value of four stage vestibular hydrops grading and asymmetric perilymphatic enhancement in the diagnosis of Menière's disease on MRI.

PURPOSE: There is still a clinical-radiologic discrepancy in patients with Menière's disease (MD). Therefore, the purpose of this study was to investigate the reliability of current MRI endolymphatic hydrops (EH) criteria according to Baráth in a larger study population and the clinical utility of new imaging signs such as a supplementary fourth low-grade vestibular EH and the degree of perilymphatic enhancement (PE) in patients with Menière's disease (MD). METHODS: This retrospective study included 148 patients with probable or definite MD according to the 2015 American Academy of Otolaryngology, Head and Neck Surgery criteria who underwent a 4-h delayed intravenous Gd-enhanced 3D-FLAIR MRI between January 2015 and December 2016. Vestibular EH, vestibular PE, cochlear EH, and cochlear PE were reviewed twice by three experienced readers. Cohen's Kappa and multivariate logistic regression were used for analysis. RESULTS: The intra- and inter-reader reliability for the grading of vestibular-cochlear EH and PE was excellent (0.7 < kappa < 0.9). The two most distinctive characteristics to identify MD are cochlear PE and vestibular EH which combined gave a sensitivity and specificity of 79.5 and 93.6%. By addition of a lower grade vestibular EH, the sensitivity improved to 84.6% without losing specificity (92.3%). Cochlear EH nor vestibular PE showed added-value. CONCLUSIONS: MRI using vestibular-cochlear EH and PE grading system is a reliable technique. A four-stage vestibular EH grading system in combination with cochlear PE assessment gives the best diagnostic accuracy to detect MD.

The Value of Diffusion-Weighted MRI in the Long-term follow-up After Subtotal Petrosectomy for Extensive Cholesteatoma and Chronic Suppurative Otitis Media.

OBJECTIVE: To report the long-term follow-up with diffusion-weighted magnetic resonance imaging (DW MRI) after subtotal petrosectomy (SP) with blind sac closure of the external auditory canal for extensive cholesteatoma and chronic suppurative otitis media. STUDY DESIGN: Retrospective clinical record study. SETTING: Tertiary referral center. PATIENTS: Thirty-one patients (31 ears) with extensive cholesteatoma and 17 patients (19 ears) with chronic suppurative otitis media without cholesteatoma who underwent SP between July 1995 and December 2015. INTERVENTIONS: All 48 patients were followed clinically and with DW MRI to rule out residual cholesteatoma. MAIN OUTCOME MEASURE: Residual cholesteatoma, indicated by a marked hyperintensity on non-echoplanar (non-EP) DW MRI. RESULTS: In the cholesteatoma group the mean interval between surgery and the latest DW MRI was 3.9 years. Seven patients presented with a residual cholesteatoma pearl. The mean interval between surgery and detection of residual disease was 3.7 years. In the chronic suppurative otitis media group the mean interval between surgery and the latest DW MRI was 5.3 years. Residual cholesteatoma was found in three patients. Mean interval between surgery and the detection of disease was 4.5 years. CONCLUSIONS: This study shows the importance of DW MRI in the follow-up after SP for cholesteatoma and chronic suppurative otitis media. A little higher residual cholesteatoma rate was found compared with earlier studies, where patients were followed only clinically. One may wonder whether reintervention is always needed or whether in selected cases with small pearls, one may still observe these by a watchful waiting policy with DW MRI.

New Imaging Modalities in Otology.

Despite steady improvements in cross-sectional imaging of the ear, current technologies still have limitations in terms of resolution, diagnosis, functional assessment and safety. In this chapter, state-of-the-art imaging techniques in current clinical practice are presented including cone-beam computerized tomography, non-echo planar imaging magnetic resonance imaging, imaging for labyrinthine hydrops and imaging of the central auditory pathways. Potential future imaging modalities are also presented, including optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) of the ear. These experimental modalities offer new opportunities for the assessment of ear structure and function. For example, middle ear structures can be visualized through the tympanic membrane, basilar membrane vibrations can be assessed through the round window and the passage of cochlear implants can be assessed in decalcified cochlear. Functional assessment of the middle ear using Doppler techniques are also discussed, including measurement of tympanic membrane and middle ear vibration amplitudes, visualization of dynamic changes, such as tensor tympani movements and movement of the tympanic membrane with breathing. These new modalities currently have limitations that preclude mainstream clinical use. For example, OCT is limited by the optical scattering of the thickened tympanic membrane and HFUS needs a coupling medium such as gel or fluid from the transducer to the imaged structure although it can visualize through thicker tissues. Nevertheless, further development of these novel techniques may provide an enhanced ability to assess the ear in conjunction with current technologies.

Delayed Intraventricular Pneumocephalus Following Shunting for Normal-Pressure Hydrocephalus.

BACKGROUND: Pneumocephalus is usually seen in trauma or cranial surgery. It is rarely reported as a delayed complication of ventriculoperitoneal shunt placement for hydrocephalus secondary to trauma, tumor, or aqueduct stenosis. We describe a case of intraventricular pneumocephalus manifesting 10 months after placement of a shunt for normal-pressure hydrocephalus. CASE DESCRIPTION: A pressure-regulated ventriculoperitoneal shunt was implanted in an 81-year-old patient after diagnosis of normal-pressure hydrocephalus. He showed postoperative clinical improvement. Routine computed tomography performed 2 months after the procedure showed no abnormalities. He presented 10 months after shunting with a subacute deterioration of gait. Imaging revealed major intraventricular pneumocephalus and a left-sided temporal porencephalic cyst with a small, bony defect in the left petrous bone. A middle fossa approach was performed, and the temporal defect was covered with fascia of the temporal muscle. This resulted in a gradual resolution of pneumocephalus. CONCLUSIONS: Pneumocephalus after shunting for NPH is rare and described as a complication only during the first 2 postoperative months. This case is unique, as the pneumocephalus developed 10 months after shunting. The combination of an occult, possibly congenital, skull base defect and the insertion of a shunt resulted in delayed intraventricular and intraparenchymal pneumocephalus.

Benchmarking adult CT-dose levels to regional and national references using a dose-tracking software: a multicentre experience.

OBJECTIVES: To benchmark CT-dose data for standard adult CT studies to regional and national reference levels using a dose-tracking system. METHODS: Data from five CT systems from three hospitals were collected over a 1- to 2.5-year period (2012-2014), using the same type of dose management system. Inclusion criteria were adult patients and standard CT-head, CT-abdomen-pelvis, CT-thorax, CT-lumbar spine, CT-pulmonary embolism, CT-cervical spine and CT-thorax-abdomen studies, with one helical scan. Volumetric CT-dose index (CTDIvol), dose length product (DLP) and scan length from 31,709 scans were analysed statistically. RESULTS: After dose optimisation CTDIvol and DLP values were below the national diagnostic reference levels (DRLs) for all CT studies and for all systems investigated. Mostly no significant differences were found between CTDIvol and DLP levels (p values ≥ 0.01) of CT studies performed on different scanners within the same hospital. Significant dose differences (p values < 0.01) were instead observed among hospitals for comparable CT studies. Dose level range and scan length differences for similar CT studies were revealed. CONCLUSIONS: Dose-tracking systems help to reduce CT-dose levels below national DRLs. However, dose and protocol data comparison between and within hospitals has the potential to further reduce variability in dose data of standard adult CT studies. KEY POINTS: • Retrospective three-centre study on dose levels of standard adult CT procedures. • Dose-tracking systems help hospitals to stay below national dose reference levels. • Dose-tracking systems help to align CT dose levels between scanners within hospitals. • Benchmarking shows CT dose level variability for similar examinations in different hospitals. • Differences in dose level range/scan length for similar CT studies are revealed.