Invasive Techniques Research Articles

Selective Sentinel Node Dissection in Melanoma with Trends and Future Directions.

Starting with its earliest descriptions, melanoma has been recognized as a tumor with a predilection for metastasis to regional lymph nodes. This tendency led to initial recommendations for very aggressive early surgical management of the regional nodal basin. However, those recommendations were the source of much controversy over nearly a century, until the minimally invasive surgical technique of sentinel lymph node (SLN) biopsy was developed by Morton, Cochran and colleagues. This technique has been evaluated in a series of prospective clinical trials, which have clarified its role and the management of lymph nodes in this disease. Current controversies relating to SLN biopsy include optimal selection of patients for the procedure, the role of gene expression profiling in initial melanoma management, and the potential therapeutic effects of SLN biopsy-based management. In addition, the SLN appears to be a rich source of data relating to the host-tumor interface and the immune microenvironment, which may advance our understanding of the biology of melanoma. Finally, although the surgical technique is well developed at this point, there may be additional technical improvements that are possible as well.

Balloon Dilatation for Congenital Nasal Pyriform Aperture Stenosis: A Novel Minimally Invasive Technique

Balloon Dilatation for Congenital Nasal Pyriform Aperture Stenosis: A Novel Minimally Invasive Technique

The Pores of Kohn, an Overlooked Pulmonary Structure: A Review

Many studies from the early 20th century on the significance of the pores of Kohn were assessed based on the pathogenesis and pathology of pneumococci pneumonia occurring in man. The pneumococci were carried in the edema fluid directly from alveolus to alveolus through the pores of Kohn and from bronchiole to bronchiole as a result of repeated aspirations, aided by breathing, coughing, and gravity. With the emerging minimally invasive and non-invasive techniques experimentations and the current medications; tackling exacerbations and improving the pulmonary function in various lung diseases remains a dilemma for clinicians and researchers. In this article, we aim to review specifically the pores of Kohn as this is the portal for the spread of infection but also lung recruitment during breathing.

Establishment of a Minimally Invasive Rat Model of Pulmonary Embolism Using Autologous Blood Clots.

Pulmonary embolism (PE) is one of the leading causes of cardiovascular death, resulting in a significant socioeconomic burden. Although current treatments primarily focus on anticoagulation and thrombolysis, there is an urgent need for a better understanding of its pathophysiology and the development of new treatment strategies. Animal models play a crucial role in understanding PE and developing new therapies for the disease, with rodents commonly used due to ethical and cost considerations. However, existing rodent models for PE are limited by a lack of standardized procedures, which hampers reproducibility and cross-study comparisons. This study aims to establish a minimally invasive rat model of PE using autologous blood clots. The model features a minimally invasive blood sampling technique, a standardized thrombus generation procedure, and minimally invasive vein access. Additionally, protocols for quantifying infarcted areas and visualizing the pulmonary arterial tree are provided. These procedures aim to improve the reliability of rodent models for studying PE progression and facilitate the development of novel treatments.

Robot-assisted congenital diaphragmatic hernia repair in adults: A case series.

Congenital diaphragmatic hernia (CDH) is a rare condition predominantly affecting neonates, with only a few cases remaining undetected until adulthood. Surgical repair is the primary treatment approach for adults with confirmed CDH. Traditionally, these procedures include laparotomy, thoracotomy, and minimally invasive techniques such as thoracoscopy and laparoscopy. However, only a few cases of robotic diaphragmatic hernia repair have been reported in recent decades. The patients, aged 31 and 71 years, presented with atypical symptoms of chest tightness and fever. Imaging studies revealed a left-sided Bochdalek CDH in 1 patient and a right-sided Morgagni CDH in the other. The patients were diagnosed as CDH in adult with different symptoms. Both patients received robot-assisted diaphragmatic hernia repair at our institution. The patients received robotic-assisted diaphragmatic hernia repair with acceptable surgery outcome and safety. There was no complication or recurrence. This case series indicates that the robotic transabdominal approach for CDH repair in adults can be an optimal minimally invasive approach for selected patients, demonstrating adequate surgical safety and favorable outcomes.

A randomized trial on three different minimally invasive decompression techniques for lumbar spinal stenosis. Five years follow-up from the NORDSTEN-SST.

The short-term clinical outcome for midline-preserving posterior decompression techniques was comparable. The aim of this study was to evaluate long-term clinical results after three different midline-preserving posterior decompression techniques. In the NORDSTEN spinal stenosis trial (NORDSTEN-SST) 437 patients were randomized to three different midline-retaining posterior decompression techniques: Unilateral laminotomy with crossover (UL), bilateral laminotomy (BL) and spinous process osteotomy (SPO). Primary outcome was the mean change in Oswestry disability index (ODI) score at five-years follow-up. Secondary outcomes were the proportion of patients classified as success, mean change in EQ-5D, ZCQ-score, NRS-score for leg and low back pain, a seven-point Global Perceived Effect (GPE) Scale and proportion of subsequential spinal surgery. The number of patients that completed follow-up data after five years was 358 (82%): In the UL, BL and SPO group the numbers were 122, 119 and 117, respectively. Mean age at baseline was 66.7 (SD 8.2) years, mean BMI was 27.8 (SD 4.1), and 172/358 (48%) were female. In the UL group the mean change was -18.2 (95% CI -21.0 -5.4), in the BL group it was -19.0 (95% CI -21.9-16.1) and in the SPO it was -18.6 (95% CI -21.6-15.7) (p = 0.917). No significant differences in the secondary outcomes between the three surgical groups were found, also the subsequent spinal surgery rates were similar. There were no significant differences in patient reported outcomes and subsequent spinal surgery rates after the three different decompression techniques at five-year follow-up.

Computer-guided implant surgery and tooth-mirroring digital workflow to treat an esthetically compromised clinical case

Background: In multidisciplinary dentistry, it is common to observe clinical cases that present multiple complications at the end of orthodontic therapy, such as differences in gingival height, alterations in size and shape of the teeth, and reduced residual spaces for implant therapies. Aim: The aim of the study was to solve an esthetic case with the help of digitally assisted prosthetic and surgical design. Methods: A young patient had been treated orthodontically for the agenesis of tooth 12 and the conoid shape of tooth 22. Previous therapy consisted of opening the space for tooth 12 by positioning a Maryland-type composite bridge, followed by reconstruction with a composite of tooth 22. Various composite reconstructions on teeth 11 and 21 were no longer adequate. Furthermore, both elements had discordant coronal axes, the diastema was observed at the incisal level, and tooth 21 was approximately 1 mm longer than tooth 11. Radiographic analysis revealed that the roots of teeth 11 and 13 converge, providing sufficient space for the insertion of a small-diameter implant. An intraoral scan and cone-beam computed tomography (CBCT) were performed; both data files were merged using surgical design software. A surgical guide was developed for the insertion of an implant in site 12. After insertion, the composite bridge, which was no longer suitable, was removed and a new temporary metal-composite Maryland bridge was positioned. Using an artificial intelligence tool of the design software, tooth 22 was isolated, mirrored, inserted in site 12 to reproduce the gingival profile, and subtracted from the digital impression. A technician then copied this emergence profile to build a zirconia prosthetic crown to be screwed on the implant. Teeth 22, 11, and 21 were restored with a lithium disilicate crown and two veneers, respectively. Results: The initial digital design and the use of a guided surgery procedure allowed for the insertion of a small diameter implant without damaging the roots of the adjacent teeth. The prosthetic design procedure, using the digital tools of the design program, made it possible to standardize and create symmetrical gingival profiles of teeth 12 and 22. The overall composition was completed by the use of minimally invasive adhesive prosthetic techniques on teeth 11, 21, and 22. Conclusion: Digital resources have become essential tools for dental professionals. The knowledge and use of technologies like intraoral scanning and CBCT, combined with various innovations such as artificial intelligence in prosthetic and implant design software, enable dentists to manage even the most complex interdisciplinary clinical cases with greater confidence. Relevance for Patients: Digital techniques are now widely used across all fields of dentistry. This has led to the need for operators of all ages to adjust their decision-making process compared to traditional techniques. These new techniques have also improved communication with patients, allowing the dental team to have a clearer understanding of the clinical path to follow and consequently offer their patients precise dentistry solutions.

A Historical Perspective and Update on Robotic Mitral Valve Surgery.

Background/Objectives: Minimally invasive techniques for mitral valve repair have evolved over the past thirty years and include mini-thoracotomies and the robotic platform. This study provides a historical perspective on minimally invasive mitral valve approaches and evaluates long-term outcomes of a large series of robotic mitral valve repairs. Methods: A single-institution, prospectively maintained registry was used to evaluate robotic mitral valve repairs performed by four surgeons from 2005 to 2023. There were 1412 robotic mitral valve repairs performed during this time and stratified by the first 120 and subsequent patients. We evaluated operative outcomes and freedom from more than 2+ mitral regurgitation at five years as well as ten-year survival. Results: Of the 1412 robotic mitral valve repairs performed, 93.6% (n = 1322) were for degenerative disease. Compared to the first 120 patients, the subsequent patients had a significant reduction in cross-clamp time (112 (IQR = 103-130) versus 75 (IQR = 65-88) min) and cardiopulmonary bypass time (153.5 (IQR = 134.5-177.5) versus 116 (IQR = 103-136) min), and all with p < 0.01. The majority of patients had posterior leaflet prolapse (65.6%, n = 926). The repair rate was 98.1%, n = 1385. Survival at ten-year follow-up for the patients included in the first 120 procedures was 91.5% (95% confidence interval (CI) = 86.4-96.6%) versus 92.8% (95% CI = 91.7-93.9%) for the patients who were in the latter group, p = 0.58. Freedom from >2+ mitral regurgitation at 5 years was 97.0% (95% CI = 95.3-98.7%) for the patients in the first 120 procedures and 92.7% (95% CI = 91.5-93.9%), p = 0.22, for those in the latter group. Conclusions: The robotic platform offers an excellent durable repair for mitral regurgitation in our experience of over 1400 patients. The robotic platform for mitral valve repair offers a teachable and safe approach to mitral valve disease for patients.

Unilateral arytenoid chondroplasty combined with minimally invasive mucosal flap plasty for bilateral vocal cord paralysis--clinical analysis of 66 cases

Objective: To analyze the efficacy of unilateral arytenoid chondroplasty combined with minimally invasive mucosal flap plasty in the management bilateral vocal cord paralysis. Methods: A total of 66 patients with bilateral vocal cord paralysis hospitalized in the First Hospital of Sun Yat-sen University from January 2018 to December 2023 were retrospectively analyzed, among whom there were 8 males and 58 females, with ages ranging from 35 to 86 years old(mean age (57.8±11.6) years). All patients underwent suspension laryngoscopic CO2 laser unilateral arytenoid chondroplasty and mucosal flap under general anesthesia. Postoperative follow-up period extended from 6 months to 6 years, with a median duration of 28 months. The study compared the degree of dyspnea and voice quality (subjective and objective evaluation) of the patients pre- and post-operatively, and analyzed the clinical differences between patients with and without preoperative or intraoperative tracheotomy, the extubation rate of tracheotomized patients, the recurrence rate, and the complication rate. Continuous variables conforming to normal distribution were tested by t-test and categorical variables by χ² test,the Wilcoxon rank-sum test was used to analyze the improvement in dyspnea before and after surgery. Results: Compared with the preoperative period, 59 patients showed improvement in postoperative dyspnea (U=161.5, P<0.01); there was no significant difference in voice disorder index 10, subjective auditory-perceptual assessment, and maximal vocalization time (P>0.05), all of which remained within the relative normal range. Tracheotomy was performed in 32 out of 66 patients, with predominantly degree Ⅲ- dyspnea (46.9%, 15/32), including 26 patients with preoperative tracheotomy and 6 patients with intraoperative tracheotomy. Among the 34 patients who did not undergo tracheotomy, the majority presented with degree Ⅱ-dyspnea (82.4%, 28/34). All patients achieved successful extubation following surgery, with a mean median time to extubation of 1 month. Conclusions: The combination of unilateral arytenoid chondroplasty and minimally invasive mucosal flap plasty represents a refined and effective therapeutic approach for bilateral vocal cord paralysis. This minimally invasive technique has the potential to reduce the rate of tracheotomy.

Can Obesity Serve as a Barrier to Minimally Invasive Mitral Valve Surgery? Overcoming the Limitations-A Multivariate Logistic Regression Analysis.

Background/Objectives: Over the past two decades, significant advancements in mitral valve surgery have focused on minimally invasive techniques. Some surgeons consider obesity as a relative contraindication for minimally invasive mitral valve surgery (MIMVS). The aim of this study is to evaluate whether the specific characteristics of obese patients contribute to increased surgical complexity and whether this, in turn, leads to worse clinical outcomes compared to non-obese patients. Furthermore, we aim to explore whether these findings could substantiate the consideration of limiting this treatment option for obese patients. We investigated the outcomes of MIMVS in obese and non-obese patients at a high-volume center in Germany staffed by an experienced surgical team well-versed in perioperative management. Methods: A total of 934 MIMVS were performed in our high-volume center in Germany from 2011 to 2023. Of these, 196 patients had a BMI of 30 or higher (obese group), while 738 patients had a BMI below 30 (non-obese group), all of whom underwent MIMVS by right minithoracotomy. Demographic information, echocardiographic assessments, surgical data, and clinical outcome parameters were collected for all patients. Results: There was no significant difference in in-hospital, 30-day, and late mortality between groups (obese vs. non-obese: 6 [3.0%] vs. 14 [1.8%], p = 0.40; 6 [3.0%] vs. 14 [1.8%], p = 0.40; 13 [6.6%] vs. 39 [5.3%], p = 0.48, respectively). Respiratory insufficiency and arrhythmia occurred more frequently in the obese group (obese vs. non-obese: 25 [12.7%] vs. 35 [4.7%], p < 0.001; 35 [17.8%] vs. 77 [10.4%], p = 0.006). Conclusions: Obesity was not associated with increased early or late mortality in patients undergoing MIMVS. However, obese patients experienced higher incidences of postoperative complications, including respiratory insufficiency, arrhythmias, delirium, and wound dehiscence. Nonetheless, a multivariate logistic regression analysis indicated that obesity itself does not contraindicate MIMVS and should not be viewed as a barrier to offering this minimally invasive approach to obese patients.

Analysis of Clinical Application of Minimally Invasive Technique in Alveolar Surgery

Objective To explore the clinical effect of minimally invasive techniques in the treatment of alveolar surgery. Methods 80 patients who underwent dental surgery from March 2023 to March 2024 were selected as study samples and randomly divided into two groups. The control group (40 cases) underwent the traditional extraction method, and the observation group (40 cases) underwent the minimally invasive technique. The integrity rate of tooth extraction, pain rate, postoperative infection rate and treatment effect were compared between the two groups. Results The integrity rate of tooth extraction, pain rate and postoperative infection rate in observation group were lower than those in control group (P &lt; 0.05). The therapeutic effect of observation group was significantly higher than that of control group (P &lt; 0.05). Conclusion Minimally invasive technique has a significant effect in the treatment of alveolar surgery, which can reduce the degree of pain and the probability of infection and improve the integrity of the alveolar.

Large nonpedunculated colorectal polyp management through the lens of an interventional endoscopist.

SummaryMinimally invasive endoscopic resection techniques are now the first-line management strategy for most large (> 20 mm) nonpedunculated colorectal polyps (LNPCPs). Appropriate technique selection depends on optical evaluation to predict lesion histopathology alongside the presence of and depth of malignant invasion. We review the indications and performance of endoscopic mucosal resection, cold snare resection, and endoscopic submucosal dissection. These complementary techniques, bolstered by site-specific technical modifications and ancillary techniques, are an effective, efficient, and safe alternative to surgery. An understanding of the role of minimally invasive endoscopic resection techniques is crucial for all endoscopists and surgeons involved in LNPCP management.

Non-invasive assessment of intracranial pressure through the eyes: current developments, limitations, and future directions.

Detecting and monitoring elevated intracranial pressure (ICP) is crucial in managing various neurologic and neuro-ophthalmic conditions, where early detection is essential to prevent complications such as seizures and stroke. Although traditional methods such as lumbar puncture, intraparenchymal and intraventricular cannulation, and external ventricular drainage are effective, they are invasive and carry risks of infection and brain hemorrhage. This has prompted the development of non-invasive techniques. Given that direct, non-invasive access to the brain is limited, a significant portion of research has focused on utilizing the eyes, which uniquely provide direct access to their internal structure and offer a cost-effective tool for non-invasive ICP assessment. This review explores the existing non-invasive ocular techniques for assessing chronically elevated ICP. Additionally, to provide a comprehensive perspective on the current landscape, invasive techniques are also examined. The discussion extends to the limitations inherent to each technique and the prospective pathways for future advancements in the field.

CT measurement of blood perfusion in hepatocellular carcinoma: from basic principle, measurement methods to clinical application

Hepatocellular carcinoma (HCC) is one of the common and fatal malignant tumors worldwide, and the burden of HCC is particularly severe in China. Physiologically, the blood supply to healthy liver is mainly from the portal vein, supplemented by the hepatic artery. While in the development of HCC, the main source of blood supply to HCC is changed from the portal vein to the hepatic artery. The characteristics of HCC vascularization are important for imaging, surgery, interventional therapy, targeted therapy, etc. Even in the future, with the development of radiation therapy technology, such as proton and heavy ion therapy and artificial intelligence technology, the dynamic changes in HCC blood perfusion can be used as a new biomarker of tumor activity to provide accurate information on the intensity modulation of radiotherapy, so that accurate measurements of HCC blood perfusion is of great significance in guiding the diagnosis and treatment of HCC. The technologies for measurement of HCC blood perfusion have developed from invasive techniques, such as inert gas scavenging, electromagnetic flowmeter, and radionuclide-labeled erythrocyte elution in the middle of the last century to the present non-invasive techniques of CT. With the development of CT imaging technology in the last 30 years, the CT-based imaging technology can assess the status of organ and tissue perfusion relatively easily and accurately. In this paper, the various CT measurement techniques of blood perfusion in HCC were categorized into three types: semi-quantitative technique, relative quantitative technique, and absolute quantitative technique. Their basic principle, scanning methods, and clinical applications were discussed to provide a reference for the diagnosis and treatment of HCC.

Gelatin-Based Polymers Can Be Processed to Highly Resilient Biocompatible Porous Hydrogel Scaffolds for Soft Tissue Regeneration Applications

Tissue regeneration relies on the mechanical properties of the surrounding environment, and it has already been shown that mechanostimulation is highly dependent on the stiffness of the native biological tissue. The main advantage of injectable hydrogels in medical applications is their ability to be delivered through minimally invasive techniques. Natural polymer-based hydrogels have been widely used in biomedical applications, due to their high biocompatibility, low immunogenicity, and similarity to soft tissues. However, the crucial combination of low stiffness with high resilience has not been achieved for natural polymers. The current study focuses on the development of novel gelatin-based injectable hydrogels for soft tissue regeneration applications, elucidating the effects of the formulation parameters on the resilience, microstructure, biocompatibility, and mechanical properties. Non-foamed hydrogels demonstrated resilience of at least 95%, while porous hydrogels maintained resilience above 90%, allowing them to withstand mechanical stresses and dynamic conditions within the body. The adjustable modulus of these hydrogels provides the necessary flexibility to mimic the mechanical properties of soft and very soft tissues, without compromising resilience. Environmental Scanning Electron Microscopy (ESEM) observations of the porous hydrogels indicated round interconnected pore structures, desired for cell migration and nutrient flow. Biocompatibility tests on fibroblasts and pre-adipocytes confirmed high biocompatibility, both directly and indirectly. In summary, structuring these new hydrogels for achieving adjustable stiffness, along with the excellent resilience and biocompatibility, is expected to enable this new technology to fit various soft tissue regeneration applications.

Analysis of the efficacy of triple-channel minimally invasive knee arthroscopy in treating popliteal cysts in children

BackgroundThis study aimed to investigate a technique for treating pediatric popliteal cysts with a triple-channel knee arthroscopic approach, hypothesizing that this technique exhibits favorable clinical outcomes with reduced recurrence rates.MethodsA retrospective analysis was conducted on the clinical data of 14 patients with symptomatic pediatric popliteal cysts admitted to the joint surgery center using an arthroscopic minimally invasive technique from December 2017 to December 2020. Arthroscopy was employed for adequate enlargement of the posterior medial flap opening between the cyst and the joint cavity and to completely resect the cyst wall. The popliteal cyst recurrence was assessed through Magnetic Resonance Imaging(MRI) at 3 and 12 months post-surgery, and the Rauschning and Lindgren scores were recorded to evaluate the clinical prognosis.ResultsA total of 14 children completed the follow-up, including 8 boys and 6 girls, with a mean age of 9.9 ± 1.1 years (5–12 years); 5 cases in the left knee and 9 cases in the right knee; the mean operative time was 19.2 ± 2.7 min (10–25 min); and the mean follow-up time was 15.1 ± 2.4 months (12–24 months). There was no intraoperative vascular or nerve injury and no incisional exudate infection. Postoperatively, posterior knee symptoms disappeared in the children, Rauschning and Lindgren scores significantly improved, and no recurrence signs were observed on MRI.ConclusionsThis study determined that the arthroscopic three-channel minimally invasive technique is effective and safe for treating popliteal cysts in children, making it worthy of clinical promotion.

Safety and Efficacy of Endoscopic Submucosal Dissection for Rectal Neoplasms Extending to the Dentate Line: A Systematic Review and Meta-analysis.

Endoscopic submucosal dissection (ESD) is a superior, minimally invasive technique compared with other snare-based endoscopic resection techniques for rectal neoplasms extending to the dentate line (RNDLs). However, performing a successful ESD in the anal canal can be challenging due to vascularity and limited scope stability. In this meta-analysis, we aim to evaluate the safety and efficacy of ESD for RNDLs. We performed a comprehensive electronic database search from January 2005 through January 2024 for studies evaluating outcomes of ESD performed for managing RNDLs. Pooled proportions were calculated using random-effect models. Heterogeneity was evaluated using I2 and Q statistics. Data were extracted from 11 studies comprising 496 patients. The pooled en bloc resection rates were 93.60% (95% CI = 90.70-95.70). The pooled R0 resection rate was 80.60% (95% CI = 70.50-87.80). The pooled recurrence rate was 4.00% (95% CI = 2.40-6.50). There was no evidence of significant heterogeneity calculated using the Q test and I2 statistic. The main adverse events were anal pain, postprocedural bleeding, and anal stricture with pooled rates of 20.20% (95% CI = 14.80-26.90), 8.20% (95% CI = 4.70-14.0), and 3.50% (95% CI = 2.10-5.70), respectively. ESD is a safe and effective option for managing RNDLs with a low recurrence rate. Adverse events such as postprocedural perianal pain, postprocedural bleeding, and anal stenosis seem to be more common compared with colorectal ESD done for more proximal lesions. However, these can typically be managed conservatively or with minimally invasive endoscopic techniques.

A differentiated approach to the surgical treatment of intraarticular fracture of the proximal tibia

Background. For a long time, the question of optimal ways and methods of surgical treatment of fractures of the proximal part of the tibia (PPT) remains debatable. The purpose was to study the results of surgical treatment of fractures of the PPT using differentiated use of minimally invasive techniques. Materials and methods. The work consisted of a prospective analysis of the treatment outcomes of 87 patients who were treated 2018 to 2023. Fractures were classified according to Schatzker. The tactics of surgical treatment depended on the type of fracture, the age of the patients and the presence of concomitant diseases. A comprehensive assessment of knee function was performed using the Knee Society Score. For X-ray assessment of the degree of progression of post-traumatic arthritis, the Resnik/Niwoyama system was used. ­Results. The results of surgical treatment were studied in terms from 6 to 24 months. 19.8 % of excellent, 57.5 % good, 15.6 % sa­tisfactory and 7.1 % unsatisfactory treatment results were obtained. Progression of post-traumatic arthritis was observed in 36 patients (28 patients at one stage, 4 subjects at 2 stages and 5 patients at 3 stages). Of the complications, 7 (8.0 %) were surgical site infections, which required debridement of the focus and longer antibiotic therapy. Over time, loss of reposition and secondary displacement were identified in 5 (5.7 %) cases. The most common complications were the progression of knee osteoarthritis, the development of contractures in 11 (12.6 %) patients. Conclusions. The use of a differential approach to the surgical treatment of intra-articular fractures of PPT, based on the severity of injuries according to Schatzker, allowed to obtain positive functional results in 77.3 % of the victims. The negative consequences of intra-articular fractures of the tibial plateau that worsen the functional outcomes of treatment include the progression of knee osteoarthritis. The degree of its manifestations is largely determined by the severity of the injury, the quality of reduction, the stability of fragment fixation, and the rationality of restorative treatment and rehabilitation.

Using fMRI to examine nonlinear mixed selectivity tuning to task and category in the human brain

Abstract Recent experimental and theoretical work has shown that nonlinear mixed selectivity, where neurons exhibit interaction effects in their tuning to multiple variables (e.g., stimulus and task) plays a key role in enabling the primate brain to form representations that can adapt to changing task contexts. Thus far all such studies have relied on invasive neural recording techniques. In this study, we demonstrate the feasibility of measuring nonlinear mixed selectivity tuning in the human brain noninvasively using fMRI pattern decoding. To do so, we examined the joint representation of object category and task information across human early, ventral stream, and dorsal stream areas while participants performed either an oddball detection task or a one-back repetition detection task on the same stimuli. These tasks were chosen to equate spatial, object-based, and feature-based attention, in order to test whether task modulations of visual representations still occur when the inputs to visual processing are kept constant between the two tasks, with only the subsequent cognitive operations varying. We found moderate but significant evidence for nonlinear mixed selectivity tuning to object category and task in fMRI response patterns in both human ventral and dorsal areas, suggesting that neurons exhibiting nonlinear mixed selectivity for category and task not only exist in these regions, but cluster at a scale visible to fMRI. Importantly, while such coding in ventral areas corresponds to a rotation or shift in the object representational geometry without changing the representational content (i.e., with the relative similarity among the categories preserved), nonlinear mixed selectivity coding in dorsal areas corresponds to a reshaping of representational geometry, indicative of a change in representational content.

Diagnostic Value of the Voltage-to-Mass Ratio in Biopsy-Proven Cardiac Amyloidosis.

The calculation of left ventricular mass varies in different studies, and reference values of the voltage-to-mass ratio for diagnosing cardiac amyloidosis (CA) are lacking. This study aimed to determine the value of the voltage-to-mass ratio in diagnosing CA and provide an optimal cut-off value for different calculation methods. We reviewed the electrocardiograms and echocardiograms of 213 consecutive biopsy-proven CA patients, 236 hypertrophic cardiomyopathy (HCM) patients, 100 hypertensive heart disease patients, and 181 healthy controls. Left ventricular mass was calculated using linear and cross-sectional area (CSA) methods. The voltage-to-mass ratios were compared between the CA group and other groups. The voltage-to-mass ratio obtained was used to build multivariate logistic regression models that predicted the log odds of developing CA. The CA group had a significantly lower voltage-to-mass ratio than the HCM, hypertensive heart disease, and healthy control groups. The voltage-to-mass ratio was an independent factor significantly associated with the CA diagnosis after adjusting for baseline characteristics. Linear and CSA methods yielded areas under the ROC curve of 0.86 and 0.90, respectively. Using the CSA method, the optimal cut-off was 16.42 mV/mm2/m2, with 89.0% sensitivity and 80.8% specificity. The voltage-to-mass ratio could differentiate patients with CA, HCM, and hypertensive heart disease from healthy controls, potentially providing an accurate and non-invasive alternative to current expensive and invasive diagnostic techniques.