Simulation-based evaluation of susceptibility distortion correction methods in diffusion MRI for connectivity analysis

Connectivity analysis on diffusion MRI data of the whole- brain suffers from distortions caused by the standard echo- planar imaging acquisition strategies. These images show characteristic geometrical deformations and signal destruction that are an important drawback limiting the success of tractography algorithms. Several retrospective correction techniques are readily available. In this work, we use a digital phantom designed for the evaluation of connectivity pipelines. We subject the phantom to a âeurooetheoretically correctâeuro and plausible deformation that resembles the artifact under investigation. We correct data back, with three standard methodologies (namely fieldmap-based, reversed encoding-based, and registration- based). Finally, we rank the methods based on their geometrical accuracy, the dropout compensation, and their impact on the resulting connectivity matrices.

Resultate und ausser- gewöhnliche Komplikationen der Chirurgie der Gehörgangexostosen [Results and extraordinary complications of surgery for exostoses of the external auditory canal].

We present a retrospective study on 22 operations of exostosis of the external auditory canal in 20 patients. 8 patients were passionated by water sports. The most frequent indication for surgery (13 operations) was recurrent external otitis or ceruminal obstruction. In 7 cases the need for a wider access to the middle ear indicated surgery. Surgery was usually performed as an outpatient procedure, maximum hospitalization was 3 days. The mean healing period was 6 (3-10) weeks. Mean follow up was 43 (3-110) months. There were no severe intraoperative complications such as facial paresis, lesions of the ossicles or of the inner ear. As intraoperative complications we found 2 perforations of the tympanic membrane, 2 expositions of the capsule of the mandibular joint, one of which was followed by chronic pain. As postoperative complications we found an early soft tissue stenosis of the external auditory canal and one late soft tissue stenosis which recurred after revision surgery. No recurrence of exostosis was seen. We describe an up to now unknown complication: the appearance of bilateral petrositis caused by staphylococcus epidermidis after bilateral surgery in an otherwise healthy patient. This study confirms that severe complications are rare, minor ones however relatively common. And that also minor complications may have a troublesome follow. Therefore and because of the potential of severe complications indication for surgery must be made cautiously and risks of the operation must not be underestimated.

Clinical and biochemical responses after Gamma Knife surgery for a dopamine-secreting paraganglioma: case report.

The efficacy of Gamma Knife surgery (GKS) in local tumor control of non-secreting paragangliomas (PGLs) has been fully described by previous studies. However, with regard to secreting PGL, only one previous case report exists advocating its efficacy at a biological level. The aims of this study were: 1) to evaluate the safety/efficacy of GKS in a dopamine-secreting PGL; 2) to investigate whether the biological concentrations of free methoxytyramine could be used as a marker of treatment efficacy during the follow-up. We describe the case of a 62-year-old man diagnosed with left PGL. He initially underwent complete surgical excision. Thirty months after, he developed recurrent biological and neuroradiological disease; the most sensitive biomarker for monitoring the disease, concentration of plasma free methoxytyramine, started to increase. GKS was performed at a maximal marginal dose of 16 Gy. During the following 30 months, concentration of free methoxytyramine gradually decreased from 0.14 nmol/l (2*URL) before GKS to 0.09 nmol/l, 6 months after GKS and 0.07 nmol/l at the last follow-up after GKS (1.1*URL), confirming the efficacy of the treatment. Additionally, at 30 months there was approximately 36.6% shrinkage from the initial target volume. The GKS treatment was safe and effective, this being confirmed clinically, neuroradiologically and biologically. The case illustrates the importance of laboratory tests taking into account methoxytyramine when analyzing biological samples to assess the biochemical activity of a PGL. In addition, the identification of methoxytyramine as a unique positive biomarker could designate it for the monitoring of tumor relapse after treatments, including Gamma Knife surgery.

Successful minimally invasive surgery for primary hyperparathyroidism: influence of preoperative imaging and intraoperative parathyroid hormone levels.

PURPOSE: Adenoma is the main parathyroid disorder leading to primary hyperparathyroidism (PHP). Minimally invasive parathyroidectomy (MIP) is recognized as a valid procedure for adenoma-related PHP. It requires precise preoperative localization combining Tc-99m-MIBI (methoxy-isobutyl-isonitrile) scintigraphy and single-photon emission computed tomography (SPECT) with x-ray computed tomography (CT) and intraoperative confirmation of successful excision by change in intact parathormone (iPTH) levels. The study aim was to assess the surgery success in relation to these two parameters. METHODS: All patients operated on for PHP from 2005 to mid-2014 at our institution were retrospectively reviewed. MIP was performed in case of precise preoperative adenoma localization on scintigraphy, absence of past cervical surgery, and absence of concomitant thyroid resection necessity. In these patients, iPTH levels were monitored intraoperatively. Confirmation criteria for iPTH values were a return to normal level or a decrease >50 % of basal iPTH level. RESULTS: There were 197 PHP operations during the study period: 118 MIP and 79 bilateral neck explorations (BNEs). The MIP success rate was 95 % (112/118) with a preoperative MIBI scan ± CT accurate in 94 % (111/118) of the patients and with correct iPTH in 90 % (106/118) of the cases. Among the 12 iPTH levels that did not meet the confirmation criteria, 10 returned to normal range by postoperative day 2. Treatment failure appeared in three patients (one BNE, two MIPs). CONCLUSIONS: Tc-99m-MIBI dual-phase scintigraphy with SPECT/CT is the key examination for functional and morphological parathyroid adenoma localization. If preoperative scintigraphy is obvious and intraoperative assessment is clear, one could possibly safely omit iPTH, as it may lead to unnecessary BNE in primary PHP.

Robotic-Assisted Surgery Improves the Quality of Total Mesorectal Excision for Rectal Cancer Compared to Laparoscopy: Results of a Case-Controlled Analysis.

BACKGROUND: The use of a robotic surgical system is claimed to allow precise traction and counter-traction, especially in a narrow pelvis. Whether this translates to improvement of the quality of the resected specimen is not yet clear. The aim of the study was to compare the quality of the TME and the short-term oncological outcome between robotic and laparoscopic rectal cancer resections. METHODS: 20 consecutive robotic TME performed in a single institution for rectal cancer (Rob group) were matched 1:2 to 40 laparoscopic resections (Lap group) for gender, body mass index (BMI), and distance from anal verge on rigid proctoscopy. The quality of TME was assessed by 2 blinded and independent pathologists and reported according to international standardized guidelines. RESULTS: Both samples were well matched for gender, BMI (median 25.9 vs. 24.2 kg/m(2), p = 0.24), and level of the tumor (4.1 vs. 4.8 cm, p = 0.20). The quality of the TME was better in the Robotic group (complete TME: 95 vs. 55 %; p = 0.0003, nearly complete TME 5 vs. 37 %; p = 0.04, incomplete TME 0 vs. 8 %, p = 0.09). A trend for lower positive circumferential margin was observed in the Robotic group (10 vs. 25 %, p = 0.1). CONCLUSIONS: These results suggest that robotic-assisted surgery improves the quality of TME for rectal cancer. Whether this translates to better oncological outcome needs to be further investigated.

Time course of error detection and correction in humans: neurophysiological evidence.

Using event-related brain potentials, the time course of error detection and correction was studied in healthy human subjects. A feedforward model of error correction was used to predict the timing properties of the error and corrective movements. Analysis of the multichannel recordings focused on (1) the error-related negativity (ERN) seen immediately after errors in response- and stimulus-locked averages and (2) on the lateralized readiness potential (LRP) reflecting motor preparation. Comparison of the onset and time course of the ERN and LRP components showed that the signs of corrective activity preceded the ERN. Thus, error correction was implemented before or at least in parallel with the appearance of the ERN component. Also, the amplitude of the ERN component was increased for errors, followed by fast corrective movements. The results are compatible with recent views considering the ERN component as the output of an evaluative system engaged in monitoring motor conflict.

Reliability of intraoperative ultrasound in margin status assessment in women undergoing breast conserving surgery

Background: Effective treatment for breast cancer requires accurate preoperative planning, developing and implementing a consistent definition of margin clearance, and using tools that provide detailed real-time intraoperative information on margin status. Intraoperative ultrasound (IOUS) may fulfil these requirements and may offer few advantages that other preoperative localization and intraoperative margin assessment techniques may notPurpose: The goal of the present work is to determine how accurate the intraoperative ultrasound should be to acquire complete surgical excision with negative histological margins in patients undergoing Breast Conservative SurgeryDesign: A diagnostic test study with a cross-sectional design carried out in a tertiary referral hospital in Girona within a Breast Pathology UnitParticipants: Women diagnosed with breast cancer undergoing a Breast Conservative Surgery in the Breast Pathology Unit at Hospital Universitari de Girona Dr. Josep Trueta

Graft materials in oral surgery: revision

Oral implantology is a common procedure in dentistry, especially for fully or partially edentulous patients. The implants must be placed in the best location from both the aesthetic and functional point of view. Because of this it is increasingly more frequent to resort to regeneration techniques that use substitutes of the bone itself, in order to be able to insert the implants in the most appropriate location. Material and Methodology: A review was performed on the literature from the last ten years based on the following search limitations: "graft materials', 'allograft', 'xenograft', 'autologous graft" and 'dentistry". Results: 241 works were obtained that after reading their respective summaries, they were reduced to 38, and 9 previous works were included in order to summarize the concepts. Discussion: Autologous grafts are the 'gold standard' of the bone regeneration. They have obvious advantages, but they also have drawbacks. This is why allogeneic and xenogeneic tissues are used. The former because of their clear similarity with the recipient's tissue and the latter due to their wide availability. Given that these grafts also have drawbacks, the industry has developed synthetic materials that have properties similar to those of human bone tissue. However, as of today, the ideal material to substitute human bone has not yet been found. In recent years the tendency has been to combine these synthetic materials with the patient's own bone, which is extracted during drilling in implant placement, with bone marrow aspiration, or with bone morphogenetic proteins. Thus the intention is to equip these substances with the osteogenic capacity. Conclusions: There is currently no ideal graft material, with the exception of those materials that come directly from the patient. We hope that in the coming years we will have products that will allow us to perform rehabilitations with better results and provide a better quality of life for our patients, especially those who have more complex situations to resolve, like the patients that are operated on for head and neck cancer

Mathematical equation correction to spectral and transport interferences in high-resolution continuum source flame atomic absorption spectrometry: determination of lead in phosphoric acid

In this work, a new mathematical equation correction approach for overcoming spectral and transport interferences was proposed. The proposal was applied to eliminate spectral interference caused by PO molecules at the 217.0005 nm Pb line, and the transport interference caused by variations in phosphoric acid concentrations. Correction may be necessary at 217.0005 nm to account for the contribution of PO, since Atotal217.0005 nm = A Pb217.0005 nm + A PO217.0005 nm. This may be easily done by measuring other PO wavelengths (e.g. 217.0458 nm) and calculating the relative contribution of PO absorbance (A PO) to the total absorbance (Atotal) at 217.0005 nm: A Pb217.0005 nm = Atotal217.0005 nm - A PO217.0005 nm = Atotal217.0005 nm - k (A PO217.0458 nm). The correction factor k is calculated from slopes of calibration curves built up for phosphorous (P) standard solutions measured at 217.0005 and 217.0458 nm, i.e. k = (slope217.0005 nm/slope217.0458 nm). For wavelength integrated absorbance of 3 pixels, sample aspiration rate of 5.0 ml min-1, analytical curves in the 0.1 - 1.0 mg L-1 Pb range with linearity better than 0.9990 were consistently obtained. Calibration curves for P at 217.0005 and 217.0458 nm with linearity better than 0.998 were obtained. Relative standard deviations (RSD) of measurements (n = 12) in the range of 1.4 - 4.3% and 2.0 - 6.0% without and with mathematical equation correction approach were obtained respectively. The limit of detection calculated to analytical line at 217.0005 nm was 10 µg L-1 Pb. Recoveries for Pb spikes were in the 97.5 - 100% and 105 - 230% intervals with and without mathematical equation correction approach, respectively.

Cognitively Empowering Internet-Based Patient Education for Ambulatory Orthopaedic Surgery Patients

Tiedollista voimavaraistumista tukeva internet-perustainen ohjaus päiväkirurgisille ortopedisille potilaille Tutkimuksen tarkoituksena oli kehittää tiedollista voimavaraistumista tukeva Internetperustainen potilasohjausohjelma sekä arvioida sitä. Tutkimusprosessi jaettiin kahteen vaiheeseen. Ensimmäisessä vaiheessa luotiin sisältö tiedollista voimavaraistumista tukevalle Internet-perustaiselle ohjaukselle päiväkirurgisia ortopedisia potilaita varten. Toisessa vaiheessa arvioitiin Internet-perustaisen ohjauksen (koeryhmä) hyväksyttävyyttä käyttäjien arvioimana ja ohjauksen tuloksia sekä verrattiin Internet-perustaisen ohjauksen (koeryhmä) tuloksia tiedollisesti voimavaraistumista tukevan sairaanhoitajan välittämään ohjauksen (kontrolliryhmä) tuloksiin. Tutkimuksen tavoitteena oli luoda uusi potilasohjausmuoto joka tarjoaa yksilöllisen, osallistavan ja aikaan ja paikkaan sitomattoman ohjauksen päiväkirurgiseen ortopediseen leikkaukseen tulevalle potilaalle. Tutkimuksen ensimmäisessä vaiheessa käytettiin kuvailevaa ja vertailevaa tutkimusmenetelmää (ennen ja jälkeen testaus). Tutkimukseen osallistui 120 päiväkirurgista ortopedista potilasta joiden tiedon odotuksia ja heille välitettyä tietoa tarkasteltiin. Tutkimuksen ensimmäisen vaiheen tuloksien ja aikaisemman voimavaraistumista käsittävän tiedon perusteella luotiin sisältö tiedollista voimavaraistumista tukevalle Internet-perustaiselle ohjaukselle. Sisältö rakentui voimavaraistavan tiedon kuudesta eri osa-alueesta. Tutkimuksen toisessa vaiheessa käytettiin randomoitua kokeellista tutkimusasetelmaa. Päiväkirurgiseen ortopediseen leikkaukseen tulevat potilaat randomoitiin koeryhmään (n=72) Internetperustaiseen ohjaukseen ja kontrolliryhmään (n=75) sairaanhoitajan välittämään ohjaukseen. Aineisto kerättiin strukturoitujen mittareiden avulla ja tulokset analysoitiin tilastollisesti. Tutkimuksen tulokset osoittavat, että kehitettyä tiedollisesti voimavaraistumista tukevaa Internet-perustaista potilasohjausmenetelmää voidaan suositella käytettäväksi ortopedisten päiväkirurgisten potilaiden ohjauksessa ja potilailla on hyvät mahdollisuudet voimavaraistua tiedollisesti sen avulla. Monipuolista tietoa sisältävä Internet-perustainen ohjaus osoittautui käyttäjien näkökulmasta hyväksyttäväksi. Vaikka Internet ohjauksen hyväksyttävyys koettiin osittain heikommaksi kuin sairaanhoitajan välittämän ohjauksen, potilaat käyttivät nettisivustoa ongelmitta ja arvioivat sen helppokäyttöiseksi. Ohjausmuodolla ei ollut vaikutusta hoidosta aiheutuneisiin kustannuksiin. Sen sijaan kustannuksista organisaatiolle voitiin puolittaa sairaanhoitajan ohjaukseen käyttämä aika Internet-perustaisen ohjauksen avulla. Internet-perustaiseen ohjaukseen osallistuneiden potilaiden tiedon taso ja kokemus tiedon riittävyydestä lisääntyivät ohjauksen jälkeen enemmän kuin sairaanhoitajan välittämään potilasohjaukseen osallistuneiden potilaiden tiedot. Ohjausmuodolla ei ollut vaikutusta potilaiden kokemien tunteiden ja oireiden voimakkuuteen. Yhteenvetona voidaan todeta, että tiedollisesti voimavaraistava Internet-perustaista ohjausta voidaan suositella vaihtoehtoiseksi menetelmäksi sairaanhoitajan välittämälle ohjaukselle päiväkirurgiseen ortopediseen leikkaukseen tuleville potilaille.

Airway surgery for obstructive sleep apnea and partial upper airway obstruction during sleep

This study analyzed the feasibility and efficacy of surgical therapies in patients with sleep-disordered breathing ranging from partial upper airway obstruction during sleep to severe obstructive sleep apnea syndrome. The surgical procedures evaluated were tracheostomy, laser-assisted uvulopalatoplasty (LUPP) and uvulopalatopharyngoplasty (UPPP) with laser or ultrasound scalpel. Obstructive sleep apnea and partial upper airway obstruction during sleep were measured with the static charge-sensitive bed (SCSB) and pulse oximeter. The patients with severe obstructive sleep apnea syndrome were treated with tracheostomy. Palatal surgery was performed only if the upper airway narrowing occurred exclusively at the soft palate level in patients with partial upper airway obstruction during sleep. The ultrasound scalpel technique was compared to laser-assisted UPPP. The efficacy of LUPP to reduce partial upper airway obstruction during sleep was assessed and histology of uvulopalatal specimen was compared to body fat distributional parameters and sleep study findings. Tracheostomy was effective therapy in severe obstructive sleep apnea. Partial upper airway obstruction and arterial oxyhemoglobin desaturation index during sleep decreased significantly after LUPP. The minimal retropalatal airway dimension increased and soft palate collapsibility decreased at the level where the velopharyngeal obstruction had occurred before the surgery. Ultrasound scalpel did not offer any significant benefits over the laser-assisted technique, except fewer postoperative haemorrhage events. The loose connective tissue as a manifestation of edema was the only histological finding showing correlation with partial upper airway obstruction parameters of SCSB. Tracheostomy remains a life-saving therapy and also long-term option when adherence to CPAP fails in patients with obstructive sleep apnea syndrome. LUPP effectively reduces partial upper airway obstruction during sleep provided that obstruction at the other levels than the soft palate and uvula were preoperatively excluded. Technically the ultrasound scalpel or laser surgeries are equal. In patients with partial upper airway obstruction the loose connective tissue is more important than fat accumulation in the soft palate. This supports the hypothesis that edema is a primary trigger for aggravation of upper airway narrowing during sleep at the soft palate level and evolution towards partial or complete upper airway obstruction during sleep.