Molecular characterisation of sporadic endolymphatic sac tumours and comparison to von Hippel-Lindau disease-related tumours

AIMS

Although inactivation of the von Hippel-Lindau gene (VHL) on chromosome 3p25 is considered to be the major cause of hereditary endolymphatic sac tumours (ELSTs), the genetic background of sporadic ELST is largely unknown. The aim of this study was to determine the prevalence of VHL mutations in sporadic ELSTs and compare their characteristics to VHL-disease-related tumours.

METHODS

Genetic and epigenetic alterations were compared between 11 sporadic and 11 VHL-disease-related ELSTs by targeted sequencing and DNA methylation analysis.

RESULTS

VHL mutations and small deletions detected by targeted deep sequencing were identified in 9/11 sporadic ELSTs (82%). No other cancer-related genetic pathway was altered except for TERT promoter mutations in two sporadic ELST and one VHL-disease-related ELST (15%). Loss of heterozygosity of chromosome 3 was found in 6/10 (60%) VHL-disease-related and 10/11 (91%) sporadic ELSTs resulting in biallelic VHL inactivation in 8/10 (73%) sporadic ELSTs. DNA methylation profiling did not reveal differences between sporadic and VHL-disease-related ELSTs but reliably distinguished ELST from morphological mimics of the cerebellopontine angle. VHL patients were significantly younger at disease onset compared to sporadic ELSTs (29 vs. 52 years, p < 0.0001, Fisher's exact test). VHL-disease status was not associated with an increased risk of recurrence, but the presence of clear cells was found to be associated with shorter progression-free survival (p = 0.0002, log-rank test).

CONCLUSION

Biallelic inactivation of VHL is the main mechanism underlying ELSTs, but unknown mechanisms beyond VHL may rarely be involved in the pathogenesis of sporadic ELSTs.

Training of CT-guided Periradicular Therapy in a Realistic Simulation Environment - Evaluation and Recommendations for a Training Curriculum

RATIONALE AND OBJECTIVES

To evaluate the training of computed tomography (CT)-guided periradicular therapy in a realistic simulation environment and to derive recommendations for a training curriculum.

MATERIALS AND METHODS

A novel simulation environment including the use of a 3D printed, patient-mimicking phantom was used to train medical students to perform CT-guided periradicular therapy of the lumbar spine. Seventeen participants underwent three training sessions (day 0, day 7, and after day 28) with six procedures per session. Procedure duration and the number of fluoroscopy image acquisitions were recorded. Participants' performance was assessed by an independent investigator using a six-point checklist scale (0 = lowest, 6 = highest). In addition, participants self-evaluated their skills and the simulation training in questionnaires.

RESULTS

Procedure durations and image acquisitions decreased after one training session (p < 0.001) without further improvement thereafter (p > 0.6). They also decreased within training sessions and were lowest after five procedures in all sessions. Performance scores improved after the first session to nearly perfect scores in the second session (mean 5.7; 95%CI: 5.5-6.0; p < 0.001) and decreased again in the third session (mean 4.9; 95%CI: 4.6-5.3; p = 0.008). Participants were satisfied with their training progress and felt adequately prepared to perform CT-guided periradicular therapies on patients after the training.

CONCLUSION

Simulation-based training of CT-guided periradicular therapy in a realistic environment is effective and should ideally be performed with one training session consisting of five procedures shortly before treating the first patient.

Multimodality cardiac computed tomography angiography and magnetic resonance with clinical-grade scanners provide robust assessment of cardiac morphology and function in rabbits

Background

Non-invasive computer tomography (CT)- and magnetic resonance (MR)-based cardiac imaging still remains challenging in rodents. To investigate the robustness of non-invasive multimodality cardiac imaging in rabbits using clinical-grade CT and MR scanners.

Methods

A total of 16 rabbits (2.7-4.0 kg) serially underwent cardiac-gated imaging using a clinical-grade 256-row CT and a 1.5 Tesla MR-scanner at baseline and at 4-month follow-up (16±1 weeks). Image analysis included image quality (5-grade scale), left ventricular (LV) volumes, LV stroke volume, LV diameters, LV wall thickness and ejection fraction (LVEF).

Results

Cardiac MR (CMR) and CT angiography (CTA) provide images with an overall good image quality (excellent or good quality: CMR 82% vs. CTA 78%, P=0.68). Linear regression analysis demonstrated a good correlation of all diameters (diam.) and volumes (vol.) as assessed by CTA and CMR (diam.: r=0.9, 95% CI: 0.8-0.9; vol.: r=0.8, 95% CI: 0.6-0.9; P<0.0001 for both). CTA-based volumetric analysis revealed slightly higher LVEF values as compared to CMR (CTA: 64%±1%, CMR: 59%±1%, P=0.002). Analysis of inter-/intra-observer agreement demonstrated excellent agreements for diameters (CMR: 98.5%/98.7%; CTA: 98.2%/97.4%) and volumes (CMR: 99.9%/98.8%; CTA 98.7%/98.7%). Finally, serial CMR- and CTA-based assessment of cardiac diameters and volumes delivered excellent intersession agreements of baseline versus follow-up data (diam.: CMR: r=0.89; CTA: r=0.92; vol.: CMR: r=0.87; CTA: r=0.96, P<0.0001 for all).

Conclusions

Multimodality non-invasive assessment of cardiac function and aortic hemodynamics is feasible and robust in rabbits using clinical-grade and MR and CT scanners. These imaging modalities could improve serial cardiac assessment for disease monitoring in preclinical settings.