Simulation of facial expressions using person-specific sEMG signals controlling a biomechanical face model

Purpose

Functional inoperability in advanced oral cancer is difficult to assess preoperatively. To assess functions of lips and tongue, biomechanical models are required. Apart from adjusting generic models to individual anatomy, muscle activation patterns (MAPs) driving patient-specific functional movements are necessary to predict remaining functional outcome. We aim to evaluate how volunteer-specific MAPs derived from surface electromyographic (sEMG) signals control a biomechanical face model.

Methods

Muscle activity of seven facial muscles in six volunteers was measured bilaterally with sEMG. A triple camera set-up recorded 3D lip movement. The generic face model in ArtiSynth was adapted to our needs. We controlled the model using the volunteer-specific MAPs. Three activation strategies were tested: activating all muscles \((\hbox {act}_\mathrm{all})\), selecting the three muscles showing highest muscle activity bilaterally \((\hbox {act}_3)\)—this was calculated by taking the mean of left and right muscles and then selecting the three with highest variance—and activating the muscles considered most relevant per instruction \((\hbox {act}_\mathrm{rel})\), bilaterally. The model’s lip movement was compared to the actual lip movement performed by the volunteers, using 3D correlation coefficients \((\rho )\).

Results

The correlation coefficient between simulations and measurements with \(\hbox {act}_\mathrm{rel}\) resulted in a median \(\rho \) of 0.77. \(\hbox {act}_3\) had a median \(\rho \) of 0.78, whereas with \(\hbox {act}_\mathrm{all}\) the median \(\rho \) decreased to 0.45.

Conclusion

We demonstrated that MAPs derived from noninvasive sEMG measurements can control movement of the lips in a generic finite element face model with a median \(\rho \) of 0.78. Ultimately, this is important to show the patient-specific residual movement using the patient’s own MAPs. When the required treatment tools and personalisation techniques for geometry and anatomy become available, this may enable surgeons to test the functional results of wedge excisions for lip cancer in a virtual environment and to weigh surgery versus organ-sparing radiotherapy or photodynamic therapy.

     

Impact of patient-reported nasal symptoms on quality of life after endoscopic pituitary surgery: a prospective cohort study

Pituitary - Endoscopic transsphenoidal surgery causes nasal morbidity and negatively affects health-related quality of life (HRQoL). Knowledge on actionable symptoms that could improve...     

Practice, efficacy, and costs of thyroid nodule evaluation: a retrospective study in a Dutch university hospital.

Fine-needle aspiration (FNA) of thyroid nodules has markedly reduced the role of thyroid scintigraphy. This is often limited to nondiagnostic or follicular (tumor) FNA classifications. In this study, we evaluated the efficacy and cost of such a strategy in a university center. From 1992-1998, 995 aspirations were done in 667 patients with palpable nodules. FNA was classified as malignant, suspicious, follicular, benign or inadequate. The Gold standard was surgery or extended follow-up, including physical examination, FNA, and/or ultrasound (US) with a time interval of half a year. Cost analysis was limited to operated patients. The first FNA yielded inadequate results in 28%, decreasing to 6% after 4 aspirations (n = 42). The other final classifications were: 76%, benign; 14%, follicular; 2%, suspicious; 1%, malignant (n = 7). Scintigraphy ((99m)Tc) suggested a hyperfunctioning autonomous nodule (adenoma) in 12% and 3% of the inadequate and follicular subset, respectively. Surgery for diagnostic reasons (n = 105) yielded 24 malignancies (23%): in 47% of suspicious, 12% of the follicular, and in all with malignant FNA. Postoperative morbidity occurred in 14 (5 laryngeal nerve paralyses) with benign histology. Major cost drivers were surgery and hospitalization: mean costs per patient amounting to Euro 3.311 in case of benign histology. We conclude that current work-up is still unable to prevent unnecessary surgery for benign thyroid nodules. Thyroid scintigraphy proved most productive in the inadequate FNA category. Improvement of the diagnostic process using immunohistochemistry and/or imaging is needed from the patient's and society's perspective.     

Association of baseline levels of markers of bone and cartilage degradation with long-term progression of joint damage in patients with early rheumatoid arthritis: the COBRA study

OBJECTIVE: The known risk factors for radiologic progression in rheumatoid arthritis (RA) are not optimally discriminative in patients with early disease who do not have evidence of radiologic damage. We sought to determine whether urinary C-terminal crosslinking telopeptide of type I (CTX-I) and type II (CTX-II) collagen (markers of bone and cartilage destruction, respectively) are associated with long-term radiologic progression in patients with early RA. METHODS: This was a prospective study of 110 patients with early RA who were participating in the COBRA (Combinatietherapie Bij Reumato?de Artritis) clinical trial and followup study, a randomized controlled trial comparing the efficacy of oral pulse prednisolone, methotrexate, plus sulfasalazine with sulfasalazine alone. We investigated the relationship between baseline levels of urinary CTX-I and CTX-II and the mean annual progression of joint destruction over a median of 4 years, as measured by changes in the modified Sharp score (average of 2 independent readers). RESULTS: In multivariate logistic regression analysis, baseline urinary CTX-I and CTX-II levels in the highest tertile were the strongest predictors of radiologic progression (Sharp score increase >2 units/year; odds ratio 7.9 and 11.2, respectively), independently of treatment group, erythrocyte sedimentation rate (ESR), Disease Activity Score in 28 joints, rheumatoid factor (RF), and baseline joint damage (Sharp score). The likelihood ratios for a positive test were 3.8 and 8.0 for CTX-I and CTX-II, respectively, which compared favorably with the likelihood ratios for the ESR (3.0), baseline joint damage (1.6), and RF (1.8). When patients were grouped according to the presence (Sharp score >/=4, n = 49) and absence (Sharp score <4, n = 61) of joint damage at baseline, CTX-I and CTX-II levels were predictive only in those without baseline joint damage (odds ratio 14.9 and 25.7, respectively). CONCLUSION: High baseline levels of urinary CTX-I and CTX-II independently predict an increased risk of radiologic progression over 4 years in patients with early RA, especially those without radiologic joint damage. Urinary CTX-I and CTX-II may be useful for identifying individual RA patients at high risk of progression very early in the disease, before erosions can be detected radiographically. Such patients may be in special need of treatments that inhibit bone and cartilage degradation.     

Stenting for restenotic lesions with the BARD XT stent

BACKGROUND: Conventional PTCA for the treatment of restenotic lesions is associated with a high rate of recurrence (30-50%). Primary stenting decreases the restenosis rate at long-term follow-up. METHODS: One-hundred consecutive patients with restenosis received a Bard XT stent. Follow-up angiography was performed after 6 months. Angiograms were compared by means of computed quantitative analysis. RESULTS: The mean pretreatment reference diameter was 2.88 +/- 0.51 mm. The mean minimal luminal diameter (MLD) increased from 1.09 +/- 0.57 mm to 2.70 +/- 0.44 mm. The percent diameter stenosis decreased from 66 +/- 13% to 15 +/- 10%. The procedural success rate was 99%. At 6 month follow-up repeat angiography was performed in 86 patients. The mean MLD was 1.74 +/- 0.67 mm with a mean diameter stenosis of 41 +/- 20%. Residual anginal complaints were reported in 29% of patients. In-stent restenosis (defined as diameter stenosis of more than 50%) occurred in 18% of the patients. CONCLUSION: Placement of the Bard XT stent in restenotic lesions is feasible, has an excellent short term outcome and yields a favorable result at 6 month follow-up angiography.     

Use of the fluid column in a cardiac catheter for emergency pacing

Given the not infrequent need for intracardiac pacemaking during intensive cardiac care, a new type of cardiac pacemaker has been designed and tested [1]. With this pacemaker the heart can be stimulated through the fluid column of any conventional catheter, provided it is filled with a 0.9% NaCl solution. This fluid column pacemaker (FCP) is of the “constant current” type. The FCP was tested in 37 animals, in 30 patients in sinus rhythm, and also in two critical patients. In addition to the pacemaker circuit, a special connector was designed, enabling a fast, effective, and safe contact between patient and pacemaker. The FCP is considered to be ideally suited for use in emergency cardiac pacing in intensive care units and other areas where sudden bradycardias may occur and where intrathoracic catheters are inserted for a variety of reasons.     

Inverse relation between iodine intake and thyroid blood flow: color Doppler flow imaging in euthyroid humans

High intake of iodine inhibits iodide trapping, iodide organification, and hormone release from the human thyroid. We investigated whether iodine intake also affects thyroid blood flow, as was suggested by a recent study in euthyroid rats. With a Color Doppler device we made 14 consecutive Duplex-Doppler registrations of both superior thyroid arteries in 10 euthyroid volunteers during baseline iodine intake (1 week), iodine restriction (2 weeks), return to baseline (1 week), and iodine excess (1 week; 80 mumol sodium iodide/day). Vessel diameters and mean flow velocity were measured on videotape recordings by a "blinded" observer. Baseline iodide excretion was 0.88 +/- 0.38 (+/- SD) mumol/day. Mean flow velocity was 13.9 +/- 4.1 cm/s, and vessel diameter was 1.07 +/- 0.22 mm. Blood flow was 7.7 +/- 3.8 mL/min.superior thyroid artery. During the low iodine diet, excretion dropped to 0.49 +/- 0.16 mumol/day, and blood flow increased to 11.0 +/- 5.0 mL/min (P less than 0.001), remaining elevated (10.3 +/- 4.4 mL/min) during the second baseline diet. During high iodide intake, blood flow averaged 5.8 +/- 3.4 mL/min (P less than 0.001), and the expected decrease in thyroid hormone levels and increase in TSH were seen. We conclude that thyroid blood flow responds inversely, and independently from TSH, to changes in iodine intake in euthyroid humans.     

Cutting balloon for in-stent restenosis: acute and long-term results

INTRODUCTION: Conventional percutaneous coronary intervention for the treatment of in-stent restenosis (ISR) has shown a high rate of ISR (30-55%). Considering the need for both extrusion of hyperplastic intima and additional stent expansion, a cutting balloon might be more effective for the treatment of ISR. METHODS: We prospectively assessed the immediate and 8-month outcome of balloon angioplasty using the Barath Cutting Balloon in 100 consecutive patients (mean age: 60.5 +/- 10.8 years, 71% male). RESULTS: In 73 lesions (73%), a good result was reached with the cutting balloon only. In 21 lesions (21%) postdilatation and in 6 lesions (6%) predilatation with a conventional balloon was necessary. The mean inflation pressure was 8.7 +/- 2.0 (range: 6.0-18.0) atm. Before the procedure the mean minimal luminal diameter (MLD) was 0.95 +/- 0.45 mm. Quantitative coronary analysis showed a mean diameter stenosis of 65%+/- 16%. Immediately after the procedure the mean MLD was 2.42 +/- 0.54 mm with a mean diameter stenosis of 19%+/- 13%. Two patients died during the follow-up period (1 stroke, 1 nonvascular). At 8-month follow-up 26 patients (26%) reported to have anginal complaints CCS class II-IV of whom 16 (16%) needed target lesion revascularization. CONCLUSION: Treatment of ISR using the Barath Cutting Balloon can be performed safely with good immediate results and a relatively low need for repeated target lesion revascularization at 8-month follow-up.