Tom Van Hoof

3D Computerized Model for Measuring Strain and Displacement of the Brachial Plexus Following Placement of Reverse Shoulder Prosthesis

The aim of the present study was to develop a method for three‐dimensional (3D) reconstruction of the brachial plexus to study its morphology and to calculate strain and displacement in relation to changed nerve position. The brachial plexus was finely dissected and injected with contrast medium and leaden markers were implanted into the nerves at predefined places. A reverse shoulder prosthesis was inserted in a cadaveric specimen what induced positional change in the upper limb nerves. Computed tomography (CT) was performed before and after this surgical intervention. The computer assisted image processing package Mimics® was used to reconstruct the pre‐ and postoperative brachial plexus in 3D. The results show that the current interactive model is a realistic and detailed representation of the specimen used, which allows 3D study of the brachial plexus in different configurations. The model estimated strains up to 15.3% and 19.3% for the lateral and the medial root of the median nerve as a consequence of placing a reverse shoulder prosthesis. Furthermore, the model succeeded in calculating the displacement of the brachial plexus by tracking each implanted lead marker. The presented brachial plexus 3D model currently can be used in vitro for cadaver biomechanical analyses of nerve movement to improve diagnosis and treatment of peripheral neuropathies. The model can also be applied to study the exact location of the plexus in unusual upper limb positions like during axillary radiation therapy and it is a potential tool to optimize the approaches of brachial plexus anesthetic blocks. Anat Rec, 291:1173‐1185, 2008.

Correlation of Contrast-Detail Analysis and Clinical Image Quality Assessment in Chest Radiography with a Human Cadaver Study

PURPOSE To determine the correlation between the clinical and physical image quality of chest images by using cadavers embalmed with the Thiel technique and a contrast-detail phantom. MATERIALS AND METHODS The use of human cadavers fulfilled the requirements of the institutional ethics committee. Clinical image quality was assessed by using three human cadavers embalmed with the Thiel technique, which results in excellent preservation of the flexibility and plasticity of organs and tissues. As a result, lungs can be inflated during image acquisition to simulate the pulmonary anatomy seen on a chest radiograph. Both contrast-detail phantom images and chest images of the Thiel-embalmed bodies were acquired with an amorphous silicon flat-panel detector. Tube voltage (70, 81, 90, 100, 113, 125 kVp), copper filtration (0.1, 0.2, 0.3 mm Cu), and exposure settings (200, 280, 400, 560, 800 speed class) were altered to simulate different quality levels. Four experienced radiologists assessed the image quality by using a visual grading analysis (VGA) technique based on European Quality Criteria for Chest Radiology. The phantom images were scored manually and automatically with use of dedicated software, both resulting in an inverse image quality figure (IQF). Spearman rank correlations between inverse IQFs and VGA scores were calculated. RESULTS A statistically significant correlation (r = 0.80, P < .01) was observed between the VGA scores and the manually obtained inverse IQFs. Comparison of the VGA scores and the automated evaluated phantom images showed an even better correlation (r = 0.92, P < .001). CONCLUSION The results support the value of contrast-detail phantom analysis for evaluating clinical image quality in chest radiography.

Optimal number of atlases and label fusion for automatic multi-atlas-based brachial plexus contouring in radiotherapy treatment planning

BackgroundThe present study aimed to define the optimal number of atlases for automatic multi-atlas-based brachial plexus (BP) segmentation and to compare Simultaneous Truth and Performance Level Estimation (STAPLE) label fusion with Patch label fusion using the ADMIRE® software. The accuracy of the autosegmentations was measured by comparing all of the generated autosegmentations with the anatomically validated gold standard segmentations that were developed using cadavers.Materials and methodsTwelve cadaver computed tomography (CT) atlases were used for automatic multi-atlas-based segmentation. To determine the optimal number of atlases, one atlas was selected as a patient and the 11 remaining atlases were registered onto this patient using a deformable image registration algorithm. Next, label fusion was performed by using every possible combination of 2 to 11 atlases, once using STAPLE and once using Patch. This procedure was repeated for every atlas as a patient.The similarity of the generated automatic BP segmentations and the gold standard segmentation was measured by calculating the average Dice similarity (DSC), Jaccard (JI) and True positive rate (TPR) for each number of atlases. These similarity indices were compared for the different number of atlases using an equivalence trial and for the two label fusion groups using an independent sample-t test.ResultsDSC’s and JI’s were highest when using nine atlases with both STAPLE (average DSC = 0,532; JI = 0,369) and Patch (average DSC = 0,530; JI = 0,370). When comparing both label fusion algorithms using 9 atlases for both, DSC and JI values were not significantly different. However, significantly higher TPR values were achieved in favour of STAPLE (p < 0,001). When fewer than four atlases were used, STAPLE produced significantly lower DSC, JI and TPR values than did Patch (p = 0,0048).ConclusionsUsing 9 atlases with STAPLE label fusion resulted in the most accurate BP autosegmentations (average DSC = 0,532; JI = 0,369 and TPR = 0,760). Only when using fewer than four atlases did the Patch label fusion results in a significantly more accurate autosegmentation than STAPLE.

Ultrasonic Assessment of Mucosal Thickness around Implants: Validity, Reproducibility, and Stability of Connective Tissue Grafts at the Buccal Aspect

PURPOSE (1) To assess validity and reproducibility of mucosal thickness (MT) registration by means of an ultrasonic device and (2) to determine the MT stability of connective tissue grafts (CTGs) when applied at the buccal aspect of single implants demonstrating alveolar process deficiency. MATERIALS AND METHODS For the validity assessment, four human cadaver edentulous maxillae were used to determine MT at 100 different sites. Soft tissue thickness as recorded with the ultrasonic device was compared with MT as registered with Micro-CT (UGent, Ghent, Belgium), taking the latter as gold standard. For the reproducibility assessment, 50 duplicate ultrasonic registrations were used. For the clinical part, 10 non-smoking patients with a single implant were included. All demonstrated alveolar process deficiency and had been provided with a provisional screw-retained crown at the time of inclusion. Following an intrasulcular incision at the buccal aspect, a CTG was inserted to thicken soft tissues. MT was assessed at t0 (before CTG), t1 (immediately after CTG), t2 (suture removal), t3 (permanent crown installation), and t4 (9 months after CTG). RESULTS There was a strong correlation between ultrasonic and Micro-CT measurements (r = 0.89, p < .001). However, the former significantly underrated MT by 0.13 mm (p = .030). There was a strong correlation between duplicate ultrasonic recordings (r = 0.99, p < .001). Seven females and three males were included in the clinical study with a mean age of 52. MT significantly increased by 0.92 mm between t0 and t1 (p = .005). Between t3 and t4, there was a slight, yet significant decrease of 0.15 mm (p = .047). CONCLUSION The ultrasonic device can be used as a non-invasive, reliable, and reproducible method to evaluate MT. Using this technology around single implants demonstrated that CTG may substantially thicken the peri-implant mucosa with acceptable stability over a 9-month period.

An Anatomically Validated Brachial Plexus Contouring Method for Intensity Modulated Radiation Therapy Planning

PURPOSE To develop contouring guidelines for the brachial plexus (BP) using anatomically validated cadaver datasets. Magnetic resonance imaging (MRI) and computed tomography (CT) were used to obtain detailed visualizations of the BP region, with the goal of achieving maximal inclusion of the actual BP in a small contoured volume while also accommodating for anatomic variations. METHODS AND MATERIALS CT and MRI were obtained for 8 cadavers positioned for intensity modulated radiation therapy. 3-dimensional reconstructions of soft tissue (from MRI) and bone (from CT) were combined to create 8 separate enhanced CT project files. Dissection of the corresponding cadavers anatomically validated the reconstructions created. Seven enhanced CT project files were then automatically fitted, separately in different regions, to obtain a single dataset of superimposed BP regions that incorporated anatomic variations. From this dataset, improved BP contouring guidelines were developed. These guidelines were then applied to the 7 original CT project files and also to 1 additional file, left out from the superimposing procedure. The percentage of BP inclusion was compared with the published guidelines. RESULTS The anatomic validation procedure showed a high level of conformity for the BP regions examined between the 3-dimensional reconstructions generated and the dissected counterparts. Accurate and detailed BP contouring guidelines were developed, which provided corresponding guidance for each level in a clinical dataset. An average margin of 4.7 mm around the anatomically validated BP contour is sufficient to accommodate for anatomic variations. Using the new guidelines, 100% inclusion of the BP was achieved, compared with a mean inclusion of 37.75% when published guidelines were applied. CONCLUSION Improved guidelines for BP delineation were developed using combined MRI and CT imaging with validation by anatomic dissection.

Asymmetry of the ULNT1 elbow extension range-of-motion in a healthy population: Consequences for clinical practice and research

OBJECTIVES To investigate the effect of isolated muscular variance, side and hand dominance on elbow-extension range-of-motion (EE-ROM) of the median nerve upper limb neurodynamic test (ULNT1). This study analyzes these variables potential to influence ULNT1 EE-ROM symmetry and the possible consequences for clinical practice and research. STUDY DESIGN Controlled laboratory study, cross-sectional. BACKGROUND No normative data exist to interpret correctly EE-ROM. Clinical interpretation is based on bilateral comparison. This procedure assumes natural EE-ROM symmetry, with lack of scientific evidence. METHODS Nineteen participants with Langers axillary arch (LAA), a muscular variant bridging the brachial plexus, were selected from 640 healthy volunteers, together with a matched control group. ULNT1 EE-ROMs were measured using the Vicon(®) optoelectronic system. RESULTS A full mixed model revealed no significant effects on EE-ROM for LAA and the variable side. Significant differences were found in EE-ROM between dominant and non-dominant sides (standard ULNT1 test position: 2.84° ± 1.60°, p = 0.0004; ULNT1 with differentiating maneuver: 3.05° ± 1.98°, p = 0.003). Approximately 30% of the subjects showed clinically detectable restriction (≥10°) of the dominant side EE-ROM. CONCLUSION Hand dominance is significantly associated with restriction of EE-ROM, which results in a clinically detectable asymmetry. This compromises the clinical procedure of comparing the patients EE-ROM to the opposite side. Erroneous conclusions could result in side to side analyses, if the effect is not taken into account in neurodynamic research.

Impact of drying and thiel embalming on mechanical properties of achilles tendons

Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post‐mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh‐frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Youngs modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Youngs modulus for the thawed fresh‐frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh‐frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens. Clin. Anat. 28:994–1001, 2015.

Effects of the topical application of an ethyl acetate fraction from Vernonia scorpioides on excisional wounds infected with Staphylococcus aureus in rats

We investigated the healing process on excisional wounds infected with Staphylococcus aureus in rats, treated with 50 µL of ethyl acetate III from Vernonia scorpioides (Lam.) Pers., Asteraceae, rifamycin diethylamide B 25 mg, or saline. The lesions were measured daily and after seven days were surgically removed and histologically processed. The results indicate a favorable action of the EAIII, demonstrated by the increased wound contraction, smaller area of necrotic tissue, good development of granulation tissue, extensive extracellular matrix deposition and epithelial regeneration. This sub-fraction was phytochemically investigated in parallel studies, revealing the presence of sesquiterpene lactones (glaucolides and hirsutinolides) such as diacethylpiptocarphol and related hirsutinolides, flavonoids and cinnamic acid derivatives and also a new polyacetylene, which have been previously published. Results support the effectiveness of V. scorpioides antimicrobial activity in infected wound healing in rats.

Correlation of clinical and physical-technical image quality in chest CT: a human cadaver study applied on iterative reconstruction

BackgroundThe first aim of this study was to evaluate the correlation between clinical and physical-technical image quality applied to different strengths of iterative reconstruction in chest CT images using Thiel cadaver acquisitions and Catphan images. The second aim was to determine the potential dose reduction of iterative reconstruction compared to conventional filtered back projection based on different clinical and physical-technical image quality parameters.MethodsClinical image quality was assessed using three Thiel embalmed human cadavers. A Catphan phantom was used to assess physical-technical image quality parameters such as noise, contrast-detail and contrast-to-noise ratio (CNR).Both Catphan and chest Thiel CT images were acquired on a multislice CT scanner at 120 kVp and 0.9 pitch. Six different refmAs settings were applied (12, 30, 60, 90, 120 and 150refmAs) and each scan was reconstructed using filtered back projection (FBP) and iterative reconstruction (SAFIRE) algorithms (1,3 and 5 strengths) using a sharp kernel, resulting in 24 image series. Four radiologists assessed the clinical image quality, using a visual grading analysis (VGA) technique based on the European Quality Criteria for Chest CT.ResultsCorrelation coefficients between clinical and physical-technical image quality varied from 0.88 to 0.92, depending on the selected physical-technical parameter. Depending on the strength of SAFIRE, the potential dose reduction based on noise, CNR and the inverse image quality figure (IQFinv) varied from 14.0 to 67.8 %, 16.0 to 71.5 % and 22.7 to 50.6 % respectively. Potential dose reduction based on clinical image quality varied from 27 to 37.4 %, depending on the strength of SAFIRE.ConclusionOur results demonstrate that noise assessments in a uniform phantom overestimate the potential dose reduction for the SAFIRE IR algorithm. Since the IQFinv based dose reduction is quite consistent with the clinical based dose reduction, an optimised contrast-detail phantom could improve the use of contrast-detail analysis for image quality assessment in chest CT imaging. In conclusion, one should be cautious to evaluate the performance of CT equipment taking into account only physical-technical parameters as noise and CNR, as this might give an incomplete representation of the actual clinical image quality performance.

Deep inspiration breath hold in the prone position retracts the heart from the breast and internal mammary lymph node region

Deep inspiration breath hold in the prone position causes a caudal shift of the heart away from the nearly unmodified breast and internal mammary lymph node region, suggesting better heart protection for left-sided whole breast irradiation with or without regional nodal radiotherapy.