Comparing algorithms for automated vessel segmentation in computed tomography scans of the lung: the VESSEL12 study

The VESSEL12 (VESsel SEgmentation in the Lung) challenge objectively compares the performance of different algorithms to identify vessels in thoracic computed tomography (CT) scans. Vessel segmentation is fundamental in computer aided processing of data generated by 3D imaging modalities. As manual vessel segmentation is prohibitively time consuming, any real world application requires some form of automation. Several approaches exist for automated vessel segmentation, but judging their relative merits is difficult due to a lack of standardized evaluation. We present an annotated reference dataset containing 20 CT scans and propose nine categories to perform a comprehensive evaluation of vessel segmentation algorithms from both academia and industry. Twenty algorithms participated in the VESSEL12 challenge, held at International Symposium on Biomedical Imaging (ISBI) 2012. All results have been published at the VESSEL12 website http://vessel12.grand-challenge.org. The challenge remains ongoing and open to new participants. Our three contributions are: (1) an annotated reference dataset available online for evaluation of new algorithms; (2) a quantitative scoring system for objective comparison of algorithms; and (3) performance analysis of the strengths and weaknesses of the various vessel segmentation methods in the presence of various lung diseases.Rudyanto, RD.; Kerkstra, S.; Van Rikxoort, EM.; Fetita, C.; Brillet, P.; Lefevre, C.; Xue, W.... (2014). Comparing algorithms for automated vessel segmentation in computed tomography scans of the lung: the VESSEL12 study. Medical Image Analysis. 18(7):1217-1232. doi:10.1016/j.media.2014.07.003S1217123218

Extended High-frequency Audiometry and Distortion Product Otoacoustic Emissions in Normal-hearing Patients with Unilateral Tinnitus

Some tinnitus patients have normal hearing on the conventional audiogram. It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which is not detected on the audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. Distortion product otoacoustic emissions (DPOAEs) provided ambiguous data of OHC function in normal-hearing tinnitus patients when compared to non-tinnitus controls. It is known that hearing loss in the extended high frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control. Data were obtained for 25 subjects with bilateral hearing thresholds 3dB. Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6, and 8 kHz. The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region

Influence of Unilateral Tinnitus on Distortion Product Otoacoustic Emission Levels

It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which may not be detected on the conventional audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. In normal-hearing tinnitus patients, DPOAEs provided ambiguous data of OHC function when compared to non-tinnitus controls. Hearing loss in the extended high-frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control. Data were obtained for 26 subjects with bilateral hearing thresholds10, 12.5, 14, and 16 kHz. The DP-grams were measured in the 0.5-8 kHz range using 65/55-dB SPL primaries and f2/f1=1.2. The data analyses included DPOAEs with S/N\u3e3 dB. Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6 and 8 kHz. The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region

Distortion Product Otoacoustic Emissions in Normal-hearing Patients with Bilateral Tinnitus and in Non-tinnitus Controls

Abstract is available through the Journal of Hearing Science

Tinnitus and Normal Hearing: A Study of 175 Cases

Introduction: Due to our actual knowledge tinnitus in most cases results from abnormal neural activity elicited at any level of auditory pathways and is interpreted in auditory cortex as a perception of sound, which is not accompanied by any mechanic activity within the cochlea. Tinnitus patients usually present various degrees of cochlear dysfunction, which can be manifested as sensorineural hearing loss, loudness intolerance, a distinct decrease of the DPOAE amplitude, recruitment or abnormal efferent reduction of OAEs through contralateral acoustic stimulation. But 8-15% of tinnitus patients present normal audiometric profiles. In these patients the mechanism of tinnitus generation remains unclear. Aim of the study: The aim of the study was to assess DPOAE levels and EHF thresholds in tinnitus subjects with normal hearing and compare the data with those from a normally hearing control group without tinnitus, in order to evaluate if any detectable high frequency cochlear dysfunction might be responsible for the tinnitus generation. Material and methods: 175 tinnitus patients (group 1 – tinnitus in left ear - 47 patients, group 2 – tinnitus in right ear – 23 patients, group 3 – bilateral tinnitus – 105 patients) and 60 controls (group 4). Inclusion criteria: age up to 40, normal otoscopic examination, type A tympanometry, normal hearing (up to 20 dB) in PTA (250-8000 Hz), no loudness intolerance, constant tinnitus for at least 6 months of stable localization (site of tinnitus has not changed from the previous localization). In each patient high frequency audiometry (at 10, 12.5, 14 and 16 kHz) and DPOAE registration (L1=65 dB SPL, L2=55 dB SPL, f2/f1= 1.2, S/N≥3 dB) were performed. Then statistical analysis was applied for comparison between left and right ears in the same group and also across different group of patients. Results: statistically significant differences were observed mainly in unilateral tinnitus group. These differences were more evident in audiometric data than DPOAE data. Leftsided tinnitus was twice more frequent than right-sided tinnitus. Few statistically significant differences were found between bilateral tinnitus group and controls. Conclusions: Unilateral tinnitus in normally hearing individuals may be caused by the damage of the basal region of the cochlea. There is greater incidence of high frequency hearing loss (above 8 kHz) in the ear with tinnitus in comparison to control group. In unilateral tinnitus group, the organ of Corti at the site of tinnitus is more seriously damaged than in the opposite ear. The asymmetry of cochlear damage may be crucial for tinnitus lateralization. Bilateral tinnitus, more frequently than unilateral one, can result from other pathologies, not connected with the organ of Corti