Parametric motion control of robotic arms: A biologically based approach using neural networks

A neural network based system is presented which is able to generate point-to-point movements of robotic manipulators. The foundation of this approach is the use of prototypical control torque signals which are defined by a set of parameters. The parameter set is used for scaling and shaping of these prototypical torque signals to effect a desired outcome of the system. This approach is based on neurophysiological findings that the central nervous system stores generalized cognitive representations of movements called synergies, schemas, or motor programs. It has been proposed that these motor programs may be stored as torque-time functions in central pattern generators which can be scaled with appropriate time and magnitude parameters. The central pattern generators use these parameters to generate stereotypical torque-time profiles, which are then sent to the joint actuators. Hence, only a small number of parameters need to be determined for each point-to-point movement instead of the entire torque-time trajectory. This same principle is implemented for controlling the joint torques of robotic manipulators where a neural network is used to identify the relationship between the task requirements and the torque parameters. Movements are specified by the initial robot position in joint coordinates and the desired final end-effector position in Cartesian coordinates. This information is provided to the neural network which calculates six torque parameters for a two-link system. The prototypical torque profiles (one per joint) are then scaled by those parameters. After appropriate training of the network, our parametric control design allowed the reproduction of a trained set of movements with relatively high accuracy, and the production of previously untrained movements with comparable accuracy. We conclude that our approach was successful in discriminating between trained movements and in generalizing to untrained movements

Incidental Thyroid Carcinoma by FDG-PET/CT: A Study of Clinicopathological Characteristics

BACKGROUND: The rising incidence of incidental thyroid carcinoma (ITC) detected during fluoro-2-deoxy-D: -glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scanning poses a challenge to clinicians. The present study aims to critically evaluate the clinicopathological characteristics of ITC detected by FDG-PET/CT. METHODS: Among the 557 patients managed at our institution, 40 (7.2%) patients were identified as having ITC. Of these, 22 patients had their tumor detected by FDG-PET/CT (PET group) and 11 by ultrasonography (USG group). Additional bedside ultrasonography +/- fine-needle aspiration (FNA) was done in all patients at their clinic visit. The clinicopathological characteristics were compared between the PET and USG groups. RESULTS: The PET group had significantly more patients with history of nonthyroidal malignancy (P < 0.001). Papillary carcinoma was the most common histological type in both groups. Despite having similar histological and prognostic features including tumor size, tumor multifocality, capsular invasion, extrathyroidal extension, and lymph node metastases, tumor bilaterality (or presence of contralateral tumor focus) was significantly more frequent in the PET than the USG group (P = 0.04). The tumors were also more advanced by the tumor-node-metastasis (TNM) staging system in the PET group (P = 0.021). None of the contralateral tumor foci were evident preoperatively. One patient in the USG group developed metastatic thyroid carcinoma in neck lymph nodes 28 months after thyroid resection. CONCLUSION: ITC by FDG-PET/CT had higher incidence of tumor bilaterality than those detected by ultrasonography. Total thyroidectomy should be considered for ITC detected by FDG-PET/CT even for tumor size <10 mm.published_or_final_versionSpringer Open Choice, 31 May 201

An Algorithm Informed by the Parathyroid Hormone Level Reduces Hypocalcemic Complications of Thyroidectomy

Ó The Author(s) 2010. This article is published with open access at Springerlink.com Background Measurement of the parathyroid hormone (PTH) level following total thyroidectomy (TTx) may allow prediction of postoperative hypocalcemia. We present an algorithmic method of managing hypocalcemia preemptively, based on the PTH level 1 h after operation. Materials and methods We examined 423 consecutive patients undergoing TTx at a single institution. A subset of patients were managed using an algorithm involving routine postoperative oral calcium administration and the early addition of oral calcitriol in patients with a low 1-h postoperative PTH level. Algorithm patients were compared to a concurrent, conventionally managed group. Outcomes measured included serum calcium levels, symptoms of hypocalcemia, postoperative complications, and receipt of intravenous (IV) calcium. Results The algorithm was applied in 135 patients, and 288 patients were managed conventionally. Critically low calcium levels (total calcium \7.5 mg/dl [1.88 mmol/l] or ionized calcium \0.94 mmol/l) were less common in algorithm patients (10.6 % vs. 25.3%; p \ 0.005). Much of this difference was attributable to the protective impact of the algorithm on patients undergoing TTx for cancer, 30% of whom developed critically low calcium levels when managed conventionally. Among patients requiring IV calcium, algorithm patients received fewer doses (1.29 vs

Trends in Prevalence of Thyroid Cancer Over Three Decades: A Retrospective Cohort Study of 17,526 Surgical Patients

INTRODUCTION: Thyroid cancer (TC) incidence has been increasing in recent years. The aim of this study was to investigate our institution-based estimates of operative volumes for TC over the last three decades. MATERIALS AND METHODS: This was a retrospective cohort study of patients undergoing thyroid surgery at our institution. Patient characteristics were reviewed in three subgroups: Group I (treated in 1981–1986), Group II (treated in 1987–2002), and Group III (treated in 2003–2012). RESULTS: TC was diagnosed in 1578/17,526 (9.0 %) thyroid operations. Incidence of TC increased from 3.7 % in Group I to 10.4 % in Group III (p < 0.001). Incidence of papillary TC increased form 40.6 % in Group I to 81.3 % in Group III (p < 0.001). In the latter group, 23.5 % of all papillary TCs were diagnosed in patients with Hashimoto’s disease. Meanwhile, incidence of anaplastic TC decreased from 16.2 % in Group I to 2.1 % in Group III patients (p < 0.001). pT1 tumors were diagnosed in 8.1 % Group I and 54.8 % Group III (p < 0.001), whereas pT4 tumors were identified in 40.5 % Group I, 2.4 % Group II, and 0.84 % Group III subjects (p < 0.001). pT3 tumors were found in 51.6 % Group I, whereas multifocal papillary TCs were found in 15.7 % Group III patients, the latter with a higher prevalence of pN1 stage (p < 0.001). CONCLUSIONS: The following trends in surgical volume for TC were identified throughout the study period: a fivefold increase of thyroid operations for TC, a threefold increase in incidence of papillary TC, and an eightfold decrease in incidence of anaplastic TC. It is of interest that a significant increase in incidence of multifocal papillary TC in young female patients with Hashimoto’s disease was found over time

Total thyroidectomy with ultrasonic dissector for cancer: multicentric experience

<p>Abstract</p> <p>Background</p> <p>We conducted an observational multicentric clinical study on a cohort of patients undergoing thyroidectomy for thyroid carcinoma. The aim of this study was to evaluate the benefits of the use of ultrasonic dissector (UAS) <it>vs.</it> the use of a conventional technique (vessel clamp and tie) in patients undergoing thyroid surgery for cancer.</p> <p>Methods</p> <p>From June 2009 to May 2010 we evaluated 321 consecutive patients electively admitted to undergo total thyroidectomy for thyroid carcinoma. The first 201 patients (89 males, 112 females) presenting to our Department underwent thyroidectomy with the use of UAS while the following 120 patients (54 males, 66 females) underwent thyroidectomy performed with a conventional technique (CT): vessel clamp and tie.</p> <p>Results</p> <p>The operative time (mean: 75 min in UAS <it>vs.</it> 113 min in CT, range: 54 to 120 min in UAS <it>vs.</it> 68 to 173 min in CT) was much shorter in the group of thyroidectomies performed with UAS. The incidence of transient laryngeal nerve palsy (UAS 3/201 patients (1.49%); CT 1/120 patients (0.83%)) was higher in the group of UAS; the incidence of permanent laryngeal nerve palsy was similar in the two groups (UAS 2/201 patients (0.99%) <it>vs.</it> CT 2/120 patients (1.66%)). The incidence of transient hypocalcaemia (UAS 17/201 patients (8.4%) <it>vs.</it> CT 9/120 patients (7.5%)) was higher in the UAS group; no relevant differences were reported in the incidence of permanent hypocalcaemia in the two groups (UAS 5/201 patients (2.48%) <it>vs.</it> 2/120 patients (1.66%)). Also the average postoperative length of stay was similar in two groups (2 days).</p> <p>Conclusion</p> <p>The only significant advantage proved by this study is represented by the cost-effectiveness (reduction of the usage of operating room) for patients treated with UAS, secondary to the significant reduction of the operative time. The analysis failed to show any advantages in terms of postoperative transient complications in the group of patients treated with ultrasonic dissector: transient laryngeal nerve palsy (1.49% in UAS <it>vs.</it> 0.83% in CT) and transient hypocalcaemia (8.4% in UAS <it>vs.</it> 7.5%in CT). No significant differences in the incidence of permanent laryngeal nerve palsy (0.8% in UAS <it>vs.</it> 1.04% in CT) and permanent hypocalcaemia (2.6% in UAS <it>vs.</it> 2.04% in CT) were demonstrated. The level of surgeons’ expertise is a central factor, which can influence the complications rate; the use of UAS can only help surgical action but cannot replace the experience of the operator.</p

Incidence and Risk Factors for Occult Level 3 Lymph Node Metastases in Papillary Thyroid Cancer

Papillary thyroid cancer (PTC) frequently disseminates into cervical lymph nodes. Lateral node involvement is described in up to 50 % patients undergoing prophylactic lateral neck dissection. This study aimed to assess this finding and identify which factors predict for occult lateral node disease. Patients with fine needle aspiration-confirmed PTC (Bethesda V or VI), without evidence of cervical lymph node metastases, underwent a total thyroidectomy with prophylactic ipsilateral central and level 3 dissection. Level 3 nodes were removed by compartmental dissection or by sampling the sentinel nodes overlying the jugular vein, according to surgeon preference. Data were collected prospectively from January 2011 to August 2014. Statistical analysis was performed by SPSS software. A total of 137 patients underwent total thyroidectomy with prophylactic ipsilateral central and level 3 dissection for PTC. The incidence of occult level 3 disease was 30 % (41/137 patients). A total of 48 % of patients (66/137) harbored occult central neck disease. A total of 80.5 % of patients with pN1b disease had macrometastases (aeyen2 mm), and 15 % exhibited skip metastases with central compartment sparing. In patients with pN1b disease, a median of 6 level 3 nodes were retrieved, with an average involved nodal ratio of 0.29. Multivariate regression demonstrated risk factors for occult lateral neck metastasis include tumor size (odds ratio 1.1), upper pole tumors (odds ratio 6.6), and vascular invasion (odds ratio 3.2) (p <0.05). PTC is associated with a significant incidence of occult central and lateral nodal metastases. In patients undergoing prophylactic central neck dissection, inclusion of level 3 dissection should be considered in patients with large upper lobe cancers