Joint reconstruction and segmentation in undersampled 3D knee MRI combining shape knowledge and deep learning

Objective.Task-adapted image reconstruction methods using end-to-end trainable neural networks (NNs) have been proposed to optimize reconstruction for subsequent processing tasks, such as segmentation. However, their training typically requires considerable hardware resources and thus, only relatively simple building blocks, e.g. U-Nets, are typically used, which, albeit powerful, do not integrate model-specific knowledge.Approach.In this work, we extend an end-to-end trainable task-adapted image reconstruction method for a clinically realistic reconstruction and segmentation problem of bone and cartilage in 3D knee MRI by incorporating statistical shape models (SSMs). The SSMs model the prior information and help to regularize the segmentation maps as a final post-processing step. We compare the proposed method to a simultaneous multitask learning approach for image reconstruction and segmentation (MTL) and to a complex SSMs-informed segmentation pipeline (SIS).Main results.Our experiments show that the combination of joint end-to-end training and SSMs to further regularize the segmentation maps obtained by MTL highly improves the results, especially in terms of mean and maximal surface errors. In particular, we achieve the segmentation quality of SIS and, at the same time, a substantial model reduction that yields a five-fold decimation in model parameters and a computational speedup of an order of magnitude.Significance.Remarkably, even for undersampling factors of up toR= 8, the obtained segmentation maps are of comparable quality to those obtained by SIS from ground-truth images.

Stereotactic radiofrequency ablation of tumors at the hepatic venous confluence

BACKGROUND

Radiofrequency ablation (RFA) is subject to "heat-sink" effects, particularly for treatment of tumors adjacent to major vessels.

METHODS

In this retrospective study, 104 patients with 137 tumors (40 HCC, 10 ICC and 54 metastatic liver tumors) close to (≤1 cm from) the hepatic venous confluence underwent stereotactic RFA (SRFA) between June 2003 and June 2018. Median tumor size was 3.7 cm (1.4-8.5) for HCC, 6.4 cm (0.5-11) for ICC and 3.8 cm (0.5-13) for metastases. Endpoints comprised safety, local tumor control, overall and disease-free survival.

RESULTS

The overall major complication rate was 16.0% (20/125 ablations), where 8 (40%) were successfully treated by the interventional radiologist in the same anesthetic session and did not prolong hospital stay. 134/137 (97.8%) tumors were successfully ablated at initial SRFA. Local recurrence (LR) developed in 19/137 tumors (13.9%). The median and overall survival (OS) rates at 1-, 3-, and 5- years from the date of the first SRFA were 51.5 months, 73.5%, 67.0%, and 49.7% for HCC, 14.6 months, 60.0%, 32.0% and 32.0% for ICC and 38.1 months, 91.4%, 56.5% and 27.9% for metastatic disease, respectively.

CONCLUSION

SRFA represents a viable alternative to hepatic resection for challenging tumors at the hepatic venous confluence.

Technical efficacy and local recurrence after stereotactic radiofrequency ablation of 2653 liver tumors: a 15-year single-center experience with evaluation of prognostic factors

PURPOSE

To assess the technical outcome and local tumor control of multi-probe stereotactic radiofrequency ablation (SRFA) in a large series of patients. Furthermore, to determine factors accounting for adverse outcomes.

MATERIAL AND METHODS

Between 2003 and 2018, 865 patients were treated by SRFA for 2653 primary and metastatic liver tumors with a median tumor size of 2.0 cm (0.5 - 19 cm). Primary technical efficacy (PTE) and local recurrence (LR) were evaluated, and possible predictors for adverse events analyzed using uni- and multi-variable binary logistic regression.

RESULTS

Overall, 2553 of 2653 tumors were successfully ablated at initial SRFA resulting in a PTE rate of 96.2%. Predictors of lower PTE rates were age > 70 years, tumor size > 5 cm, number of probes, location close to liver capsule/organs and segment II. LR occurred in 220 of 2653 tumors (8.3%) with the following predictors: age, tumor type/size, conglomerates, segments I/IVa/IVb, number of probes and location close to major vessels/bile duct. Multivariable analysis revealed tumor size > 5 cm (odds ratio [OR] 3.153), age > 70 years (OR 1.559), and location in segment II (OR 1.772) as independent prognostic factors for PTE, whereas tumor location close to major vessels (OR 1.653) and in segment IVb (OR 2.656) were identified as independent prognostic factors of LR.

CONCLUSIONS

Stereotactic RFA is an attractive option in the management of primary or metastatic liver tumors with good local tumor control, even in large tumors. The presented prognostic factors for adverse local oncological outcome might help to stratify unfavorable tumors for ablation.

Heart rate estimation from ballistocardiographic signals using deep learning

Objective.Ballistocardiography (BCG) is an unobtrusive approach for cost-effective and patient-friendly health monitoring. In this work, deep learning methods are used for heart rate estimation from BCG signals and are compared against five digital signal processing methods found in literature.Approach.The models are evaluated on a dataset featuring BCG recordings from 42 patients, acquired with a pneumatic system. Several different deep learning architectures, including convolutional, recurrent and a combination of both are investigated. Besides model performance, we are also concerned about model size and specifically investigate less complex and smaller networks.Main results.Deep learning models outperform traditional methods by a large margin. Across 14 patients in a held-out testing set, an architecture with stacked convolutional and recurrent layers achieves an average mean absolute error (MAE) of 2.07 beat min^-1, whereas the best-performing traditional method reaches 4.24 beat min^-1. Besides smaller errors, deep learning models show more consistent performance across different patients, indicating the ability to better deal with inter-patient variability, a prevalent issue in BCG analysis. In addition, we develop a smaller version of the best-performing architecture, that only features 8283 parameters, yet still achieves an average MAE of 2.32 beat min^-1on the testing set.Significance.This is the first study that applies and compares different deep learning architectures to heart rate estimation from bed-based BCG signals. Compared to signal processing algorithms, deep learning models show dramatically smaller errors and more consistent results across different individuals. The results show that using smaller models instead of excessively large ones can lead to sufficient performance for specific biosignal processing applications. Additionally, we investigate the use of fully convolutional networks for 1D signal processing, which is rarely applied in literature.

Ground-truth-free deep learning for artefacts reduction in 2D radial cardiac cine MRI using a synthetically generated dataset

In this work, we consider the task of image reconstruction in 2D radial cardiac cine MRI using deep learning (DL)-based regularization. As the regularization is achieved by employing an image-prior predicted by a pre-trained convolutional neural network (CNN), the quality of the image-prior is of essential importance. The achievable performance of any DL-based method is limited by the amount and the quality of the available training data. For fast dynamic processes, obtaining good-quality MR data is challenging because of technical and physiological reasons. In this work, we try to overcome these problems by a transfer-learning approach which is motivated by a previously presented DL-method (XT,YT U-Net). There, instead of training the network on the whole 2D dynamic images, it is trained on 2D spatio-temporal profiles (xt,yt-slices) which show the temporal changes of the imaged object. Therefore, for the training and test data, it is more important that their spatio-temporal profiles share similar local features rather than being images of the same anatomy. This allows us to equip arbitrary data with simulated motion that resembles the cardiac motion and use it as training data. By doing so, it is possible to train a CNN which is applicable to cardiac cine MR data without using ground-truth cine MR images for training. We demonstrate that combining XT,YT U-Net with the proposed transfer-learning strategy delivers comparable performance to CNNs trained on cardiac cine MR images and in some cases even qualitatively surpasses these. Additionally, the transfer-learning strategy was investigated for a 2D and 3D U-Net. The images processed by the the CNNs were used as image-priors in the CNN-regularized iterative reconstruction. The XT,YT U-Net yielded visibly better results than the 2D U-Net and slightly better results than the 3D U-Net when used in combination with the presented transfer learning-strategy.

Neural networks-based regularization for large-scale medical image reconstruction

In this paper we present a generalized Deep Learning-based approach for solving ill-posed large-scale inverse problems occuring in medical image reconstruction. Recently, Deep Learning methods using iterative neural networks (NNs) and cascaded NNs have been reported to achieve state-of-the-art results with respect to various quantitative quality measures as PSNR, NRMSE and SSIM across different imaging modalities. However, the fact that these approaches employ the application of the forward and adjoint operators repeatedly in the network architecture requires the network to process the whole images or volumes at once, which for some applications is computationally infeasible. In this work, we follow a different reconstruction strategy by strictly separating the application of the NN, the regularization of the solution and the consistency with the measured data. The regularization is given in the form of an image prior obtained by the output of a previously trained NN which is used in a Tikhonov regularization framework. By doing so, more complex and sophisticated network architectures can be used for the removal of the artefacts or noise than it is usually the case in iterative NNs. Due to the large scale of the considered problems and the resulting computational complexity of the employed networks, the priors are obtained by processing the images or volumes as patches or slices. We evaluated the method for the cases of 3D cone-beam low dose CT and undersampled 2D radial cine MRI and compared it to a total variation-minimization-based reconstruction algorithm as well as to a method with regularization based on learned overcomplete dictionaries. The proposed method outperformed all the reported methods with respect to all chosen quantitative measures and further accelerates the regularization step in the reconstruction by several orders of magnitude.

Intraventricular Pressure in Non-communicating Hydrocephalus Patients Before Endoscopic Third Ventriculostomy

Background

In patients with non-communicating hydrocephalus impairment of cerebral compliance can occur pre- but also intraoperatively.

Methodology

In such patients (n = 6) undergoing endoscopic third ventriculostomy (ETV), the present study aimed to investigate the effect of ETCO2 (e.g 40 mmHg and 60 mmHg) and positive end-expiratory pressure (PEEP) (e.g. 6 cm and 12 cm H2O) on intraventricular pressure (IVP).

Findings

Before but not after ETV, hypercapnia in contrast to PEEP increased IVP.

before ETV

(PEEP-6/ ETCO2-40: 2.6 ± 2.4 mmHg) vs. (PEEP-6/ ETCO2-60: 12 ± 6.4 mmHg*); (PEEP-12/ ETCO2-40: 4.2 ± 4.1 mmHg) vs. (PEEP-12/ ETCO2-60: 13.7 ± 7.6 mmHg*), * significant, P ≤ 0.05.

after ETV

(PEEP-6/ ETCO2-40: 2.0 ± 1.2 mmHg) vs. (PEEP-6/ ETCO2-60: 4.4 ± 3.1 mmHg); (PEEP-12/ ETCO2-40: 1.6 ± 1.3 mmHg) vs. (PEEP-12/ ETCO2-60: 6.6 ± 2.6 mmHg), * significant, P ≤ 0.05).

Conclusion

Patients with non-communicating hydrocephalus showed that hypercapnia but not PEEP increases significantly IVP before but not after ETV.

Stereotactic Radiofrequency Ablation of Liver Tumors in Octogenarians

Purpose: This study aimed to evaluate the efficacy and overall clinical outcome of patients over the age of 80 undergoing stereotactic radiofrequency ablation (SRFA) and to compare the results to a younger population with propensity score matching.

Materials and Methods: Between 2006 and 2018 36 patients aged between 80 and 90 years underwent 46 SRFA sessions of 70 primary and secondary liver tumors. For comparison of treatment safety and efficacy 36 younger patients were selected with propensity score matching by the R package “MatchIt” in this retrospective, single-center study.

Results: 68/70 tumors were successfully ablated at first ablation session (97% primary technical efficacy rate). Local tumor recurrence developed in 5 of 70 nodules (7.1%). The complication rate above Clavien-Dindo Grade III was 6.5% (3 of 46). The overall survival (OS) rates at 1-, 3-, and 5- years from the date of the first SRFA were 84.6, 50.5, and 37.9% for HCC patients and 87.5%, 52.5% at 1-, and 3-years for CRC patients. The disease-free survival (DFS) for HCC patients after SRFA was 79.1, 35.6, and 23.7%, at 1-, 3-, and 5- years, and 75%, 22.5% at 1-, and 3-years for CRC patients. There were no significant differences in terms of technical efficacy, local recurrences, major complications, OS and DFS compared to the control group.

Conclusion: SRFA in octogenarians is a safe, feasible and useful option in the management of primary or metastatic liver tumors with no significant difference in outcomes compared to a younger control group.

Ejection Wave Segmentation for Contact-Free Heart Rate Estimation from Ballistocardiographic Signals

We present a new algorithm for peak detection in ballistocardiographic (BCG) signals and use it for heart rate estimation. Systolic complexes of the BCG signal are enhanced and coarse heart beat locations estimated. Ejection waves I, J and K are detected simultaneously around coarse locations, only using detection of local maxima and weighted summation of peak heights. Due to a lack of reference BCG annotations, the algorithm's performance is assessed by using the detected peaks for heart rate estimation. On a dataset acquired with a pneumatic BCG system, we evaluate the heart rate estimation performance and compare the introduced algorithm against other methods found in literature. The dataset is gathered from 42 patients in a clinical environment and provides low-quality signals taken from a realistic scenario. With a mean absolute percentage error of 2.58 % at 65 % coverage, the presented method is on par with the best-performing state-of-the-art algorithms investigated. Limits of agreement (5th/95th percentiles) in a comparison with ECG-based heart rate measurements lie within P₅ = -3.63 and P₉₅ = 5.78 beat/min.

How Bispectral Index Compares to Spectral Entropy of the EEG and A-line ARX Index in the Same Patient

Background

Bispectral index (BIS) monitoring of depth of anesthesia has pioneered the field for more recent monitoring devices like the A-line ARX Index (AAI) or the state (SE) and response entropy (RE) monitoring devices. Following an observational design the present study aimed to simultaneously compare in the same patient recorded BIS, AAI and entropy values.

Methods

Data from patients (n = 32) undergoing minor gynecological operations were analyzed. For all patients, standardized anesthesia was used. Before induction of anesthesia AEP electrodes, BIS and entropy sensors were simultaneously placed on the forehead and recordings were started at 3 minutes before induction and continued until patient transfer to the postanesthesia care unit. Markers were set at defined landmarks.

Results

Anesthesia reduced mean BIS, AAI and entropy values. During uneventful, and even more pronounced, during eventful anesthesia BIS/ entropy and BIS/ AAI values showed better correlation than did AAI and entropy values. The prediction probability (Pk) of AAI (0.824 ± 0.036) and RE (0.786 ± 0.040) or SE (0.781 ± 0.040) for preanesthesia awake, postanesthesia awake or anesthesia was comparable and significantly greater than that of BIS (0.705 ± 0.047). However, only 20% of BIS, AAI and entropy values simultaneously categorized the state of the patient as awake, inadequate anesthesia, optimal anesthesia or deep anesthesia.

Conclusion

The prediction probability (Pk) of entropy and AAI was comparable and better than that of BIS. However, agreement between BIS, AAI and entropy measurements on patient state was poor.

Publication output in telemedicine during the period January 1964 to July 2003

The MEDLINE database was used to survey the period January 1964 to July 2003 for the number of publications relating to telemedicine ( n = 5911), as well as their distribution by country ( n = 42). Publications per million inhabitants were then correlated with each country's population density, gross national product, human development index (HDI) and number of PCs per 1000 inhabitants. Telemedicine publications made up 0.05% of all medical publications cited in MEDLINE. American and European countries along with others classified as industrialized produced 97% of all telemedicine publications. In terms of publications per million inhabitants, Norway and Finland took the lead. There were significant correlations between telemedicine publications per capita and HDI ( r = -0.60), number of PCs per 1000 inhabitants ( r = 0.73) and gross national product per capita ( r = 0.69), but not population density ( r = -0.12).

Acceptance of telemedicine and new media: a survey of Austrian medical students

Telemedicine and new media (e.g. the Internet, tele-teaching and tele-learning) are increasingly being used in medicine. We surveyed the awareness and acceptance of these developments on the part of medical students ( n =750) at the University of Innsbruck. A 16-item questionnaire was handed out in randomly chosen medical classes and collected immediately after completion, which resulted in a response rate of 99.9%. Nearly all of the students used the Internet regularly (68%) or at least sometimes (30%). Telemedicine was already known to most of the students, mainly from articles in magazines and newspapers (41%), but the great majority of them (95%) reported that they did not know about the telemedicine lectures offered by the University of Innsbruck. Most students (75%) thought that they would benefit from tele-teaching or tele-learning. The survey suggested that medical schools should offer more special lectures, as well as undergraduate or postgraduate qualifications in telemedicine. The marketing of such opportunities needs to be improved.

A new guidance device facilitates percutaneous puncture of the foramen ovale in human cadavers

PURPOSE

Trigeminal neuralgia is the most common neurological cause for facial pain. Contemporary interventional treatment relies on surgical microvascular decompression or, alternatively, percutaneous interventions targeting the semilunar ganglion via the foramen ovale. For the latter approach, only free-hand punctures using fluoroscopy devices have been reported. Therefore, the present study aimed to evaluate a new fluoroscopy-based guidance device for transforaminal puncture.

METHODS

Two experienced examiners punctured the foramen ovale bilaterally free-hand, and using a guidance device in human cadavers (n = 9). The number of attempts for puncture was recorded. A new attempt was counted each time the needle had to be retracted for redirection.

RESULTS

As compared to the free-hand puncture of the foramen ovale (4.44 +/- 2.79), the new guidance device significantly reduced the number of trials needed (1.37 +/- 0.69).

CONCLUSION

The employment of a guidance device facilitated percutaneous transforaminal puncture and resulted in a significantly decreased number of puncture attempts as compared to free-hand techniques in human cadavers.

Evaluation of aortic cannula jet lesions in a porcine cardiopulmonary bypass (CPB) model

In cardiosurgery patients atherosclerotic debris displaced from the cannulation site but also from the opposite aortic wall by the "sandblast-like" effect of the high-pressure jet emanating from the cannula is a potential source of intraoperative arterial embolization and consequently postoperative neurologic dysfunction. The present study examined the extent to which shear stress exerted on the intact aortic intima by an aortic cannula jet stream can cause endothelial lesions that promote thrombogenesis and consequently thrombembolism. A single-stream, straight-tip aortic cannula was used in a porcine cardiopulmonary bypass (CPB) model. Following a 120-minute CPB pump run, a 60-minute stabilization period was allowed before sacrificing the pigs (N.=40) for histological evaluation of the ascending aorta and the brain. Opposite the cannulation site endothelial lesions (diameter: 3.81±1.3 mm; depth: 0.017±0.003 mm) were present in 22.5% (9/40) of aortic specimens. Cerebral thrombembolic lesions were not found. The present study showed that single-stream, straight-tip aortic cannulas caused jet lesions of the formerly intact aortic endothelium opposite the cannulation site in 22.5% of cases in a porcine CPB model.

Factors influencing blood transfusion requirements in robotic totally endoscopic coronary artery bypass grafting on the arrested heart

OBJECTIVE

Robotic technology enables totally endoscopic coronary artery bypass grafting (TECAB) procedures. These operations can be performed on either the beating or arrested heart. One challenge of the latter version is a potentially increased need for blood transfusions. We investigated factors associated with transfusion requirements in totally endoscopic coronary artery bypass on the arrested heart (AH-TECAB).

PATIENTS AND METHODS

A total of 161 patients, 124 males and 37 females, aged 59 (31-77 years) years, with European System for Cardiac Operative Risk Evaluation (EuroSCORE) 1 (0-7) underwent AH-TECAB using the daVinci telemanipulation system. The Heartport/Cardiovations™ or ESTECH-RAP™ systems were applied for remote access perfusion and aortic endoocclusion. In all cases, the operation was carried out in moderate hypothermia and cardiac arrest using cold crystalloid cardioplegia mixed with blood.

RESULTS

After 20 cases, the blood-transfusion rate dropped from 69% to 44%. The overall median number of transfusions was 1 (0-21). The following pre- and intra-operative factors showed a strong association with the application of packed red blood cells (PRBCs): preoperative haemoglobin level (p < 0.001), female gender (p < 0.001), shorter height (p < 0.001), lower weight (p < 0.001), long operative time (p < 0.001) and long cardiopulmonary bypass time (p = 0.001), intra-operative surgical problem (p < 0.001) and conversion to a larger thoracic incision (p < 0.001). Postoperatively, patients with longer ventilation time (p < 0.001) and those needing revision for bleeding (p < 0.001) also received significantly more PRBCs.

CONCLUSION

We conclude that multiple factors are associated with increased blood transfusion requirements in AH-TECAB. However, the transfusion rate can be reduced with experience. Identification of these factors may help in avoiding the application of blood products in the next generation of AH-TECAB procedures.

Increased activated Akt expression in renal cell carcinomas and prognosis

Renal carcinogenesis is promoted by overexpression of the activated serine/ threonine kinase Akt (p-Akt) and supposedly a concomitant reduction in phosphatase and tensin homologue deleted on chromosome 10 tumour suppressor gene (PTEN), which normally inhibits the activation of Akt. Because promising anti-cancer therapies increasingly focus on pathways involving p-Akt and PTEN, the present study evaluated the expression of p-Akt in renal cell carcinomas and compared it with prognosis. P-Akt and PTEN expression were analysed in a tissue microarray (TMA) from renal cell carcinoma (n = 386) and adjacent uninvolved renal tissue (n = 32) specimens. Increased p-Akt was found more often in the nucleus than in the cytoplasm, and PTEN was concomitantly reduced in about 50% of cases. Neither tumour grade nor stage influenced p-Akt expression, whereas the clear cell and papillary subtypes showed increased p-Akt more often than did the chromophobe or sarcomatoid types. Increased cytoplasmic and nuclear p-Akt levels were independent prognostic factors for diminishing patient survival. The present study found significantly increased nuclear but also cytoplasmic p-Akt expression in renal cell carcinoma subtypes. Increased nuclear and cytoplasmic p-Akt was an independent prognostic factor for diminishing patient survival. The considerable number of high-grade and high-stage RCC showing increased p-Akt and reduced PTEN would justify further evaluation of therapeutic concepts based on inhibitors of the PI3K/p-Akt/mTOR pathway.

Effectiveness and safety of total endoscopic left internal mammary artery bypass graft to the left anterior descending artery

Totally endoscopic coronary artery bypass grafting (CABG) has become a feasible option using robotic technology and remote access perfusion techniques. The aim of this study was to determine the progression of the procedure's performance in the currently largest single-center series of arrested-heart totally endoscopic CABG. From 2001 to 2007, arrested-heart totally endoscopic CABG was performed in 100 patients (median age 59 years, range 46 to 70; 81 men, 19 women). All patients received left internal mammary artery grafts to the left anterior descending artery using the da Vinci Surgical System. Remote-access femoral perfusion and aortic balloon endo-occlusion were used in all patients. The series was divided into 4 phases: phase 1 (patients 1 to 25), phase 2 (patients 26 to 50), phase 3 (patients 51 to 75), and phase 4 (patients 76 to 100). The conversion rates to larger thoracic incisions were 7 of 25 (28%) in phase 1, 2 of 25 (8%) in phase 2, 1 of 25 (4%) in phase 3, and 1 of 25 (4%) in phase 4 (p = 0.018). Operative times and hospital stays decreased significantly with each subsequent phase, and clinical outcome showed corresponding improvements. There was no perioperative mortality. For the whole patient series, 5-year postoperative survival, freedom from angina, and freedom from major adverse cardiac and cerebral events were 100%, 91%, and 89%, respectively. In conclusion, after an initial steep learning curve, completely endoscopic left internal mammary artery-to-left anterior descending CABG can be performed safely, with low conversion rates. The learning curve for operative times and improvements in clinical outcome continued even at 100 procedures.

Distal leg protection for peripheral cannulation in minimally invasive and totally endoscopic cardiac surgery

BACKGROUND

The introduction of minimally invasive and totally endoscopic cardiac surgery is associated with increased use of femoral artery perfusion. Selective antegrade perfusion of the cannulated artery may be a helpful strategy to avoid ischemia of the lower extremities. The aim of the study was to evaluate the efficacy of selective distal vessel perfusion under continuous monitoring of oxygen saturation using near-infrared spectroscopy (NIRS).

METHODS

All patients (n = 236) who underwent peripheral cannulation for remote access perfusion and endoaortic balloon occlusion for minimally invasive or totally endoscopic cardiac surgery were prospectively analyzed. Perioperative complications, creatine kinase levels, and major complications at the long-term follow-up were recorded.

RESULTS

Minor or major complications of leg perfusion occurred in only 4 patients (1.7%); the complications in 2 of the patients were associated with an additional arterial cannula placed at the contralateral side. NIRS monitoring revealed diminished perfusion in 5 cases. Even patients with complications associated with remote-access perfusion had a rapid recovery, and no residual peripheral vascular complication was detected during follow-up.

CONCLUSIONS

The use of antegrade selective perfusion of the lower extremity at the side of peripheral cannulation for port-access perfusion and endoaortic occlusion is of utmost importance in patients undergoing minimally invasive or endoscopic cardiac surgery. NIRS monitoring has proved to be very helpful for the diagnosis of impaired leg perfusion.

Does obesity affect operative times and perioperative outcome of patients undergoing totally endoscopic coronary artery bypass surgery?

More and more patients undergoing coronary artery bypass grafting (CABG) are overweight. This patient group suffers from wound healing problems more often than normal-weight patients. Therefore, avoiding sternotomy in obese patients by using an endoscopic technique could be a promising approach. Robotic technology enables totally endoscopic coronary artery bypass grafting (TECAB) procedures. We investigated whether the intra-operative-times or perioperative-outcome after TECAB-procedure are negatively affected by obesity. Patients [n=127, 101 male, 26 female, median age 59 (31-77) years], undergoing arrested-heart TECAB procedure were enrolled. The median body mass index (BMI) in this patient cohort was 26 (19-38). In detail, 27 patients were normal-weight (BMI <or= 25 kg/m(2)), 67 patients were overweight (BMI 25.1-30 kg/m(2)), 29 patients were obese (BMI 30.1-33.9 kg/m(2)) and four patients were morbidly obese (BMI >or= 34 kg/m(2)). There was no correlation between BMI (1) left internal mammary artery (LIMA) takedown-time [Spearman-rank correlation coefficient (R)=0.02; P=n.s.], (2) lipectomy and pericardiotomy-time (R=0.042, P=n.s.), (3) total operative-time (R=-0.083: P=n.s.), (4) cardiopulmonary-bypass-time (R=-0.012; P=n.s.), (5) aortic-endoocclusion-time (R=-0.055; P=n.s.), (6) mechanical-ventilation-time (R=0.001, P=n.s.), (7) length of ICU-stay (R=0.04; P=n.s.), (8) length of hospital-stay (R=-0.103; P=n.s.) or (9) occurrence of intra- and/or postoperative adverse events. In overweight, obese but also morbidly obese patients the TECAB procedure did not increase operative times or the rate of intra- or postoperative complications. This patient group, therefore, benefits from this less traumatic version of coronary surgery.

Point-of-care whole blood impedance aggregometry versus classical light transmission aggregometry for detecting aspirin and clopidogrel: the results of a pilot study

BACKGROUND

We determined whether whole blood impedance aggregometry using the Multiplate detects the effects of antiplatelet drugs as reliably as does classical light transmission aggregometry (LTA) or the platelet function analyzer PFA-100(R).

METHODS

Multiplate (M) assays, measuring changes in electrical resistance as aggregation units over time (AU*min), and LTA assays induced by collagen (COL), adenosine diphosphate (ADP) or arachidonic acid (AA) and PFA-100 testing, using epinephrine (PFA100-EPI) or ADP (PFA100-ADP) cartridges, were performed simultaneously using arterial blood samples obtained before induction of anesthesia in 70 consecutive patients scheduled for elective coronary artery bypass grafting. Patients in group A (n = 48) served as controls, patients in group B (n = 11) received aspirin 100 mg/d and those in group C (n = 11) aspirin 100 mg/d and clopidogrel 75 mg/d until the day before surgery.

RESULTS

In controls the median (1st, 3rd quartiles) change in impedance AU*min for M-COL (374 [231-469]) was significantly greater than in patients receiving aspirin (164 [86-211], P = 0.0009) or receiving aspirin and clopidogrel (118 [101-244], P = 0.004). M-ADP values in controls were 258 (158-389), in patients receiving aspirin 261 (159-393), and in patients receiving aspirin and clopidogrel 88 (48-231, P = 0.054). M-AA values were significantly lower in patients receiving aspirin alone (45 [28-60], P = 0.0004) or aspirin and clopidogrel (44 [26-221], P = 0.008) than in controls (200 [86-345]). The areas under the receiver operating characteristic curves indicating the ability to discriminate patients taking aspirin from those not taking aspirin were comparable for COL and AA assays using whole blood impedance aggregometry or classical LTA (M-COL 0.84 [P = 0.001], LTA-COL 0.85 [P = < .001], M-AA 0.84 [P = < .001] and LTA-AA 0.87 [P = < .001]), but only 0.74 for PFA-100-EPI (P = 0.03). Similarly, for discrimination of patients not taking antiplatelet drugs from patients taking clopidogrel and aspirin the areas under the receiver operating characteristic curve were also comparable for both aggregometry methods M-COL 0.77 (P = 0.006), LTA-COL 0.78 (P = 0.004), M-ADP 0.74 (P = 0.015), LTA-ADP 0.73 (P = 0.018).

CONCLUSION

Results achieved with the bedside Multiplate assays were not different than those obtained with classical aggregometry for detecting the effects of aspirin and clopidogrel in preoperative patients scheduled for elective cardiac surgery.

Near infrared spectroscopy for controlling the quality of distal leg perfusion in remote access cardiopulmonary bypass

The prevention of leg ischemia is necessary in all patients undergoing femoral artery cannulation for extracorporeal circulation. Near infrared spectroscopy (NIRS) is an established non-invasive method for measuring tissue oxygen saturation. Ten patients underwent robotically assisted endoscopic coronary surgery or ASD repair on the arrested heart using aortic endo-occlusion catheters. They were monitored by transcutaneous NIRS (placed on both lower legs) for quality control of distal leg perfusion during femoral access cardiopulmonary bypass. The baseline NIRS values were 61 (52-80) on the cannulated side versus 70 (53-80) on the contralateral leg (p=n.s.). During clamping of the femoral artery for installation of the remote access perfusion system the tissue oxygen saturation dropped to 38 (18-58) (p=0.001 vs baseline) while it remained stable on the contralateral leg. After successful implantation of the distal leg perfusion the NIRS values normalized to similar amounts on both legs. We conclude that transcutaneous NIRS of the lower legs might be a useful non-invasive tool for monitoring leg perfusion in patients undergoing extracorporeal circulation via the femoral vessels.

Tissue microarrays from renal cell tumors: exclusion criteria and rate of exclusion

OBJECTIVES

Exclusion of tissue microarray (TMA) cores can cause the total loss of a tumor case, and this can have a potentially negative effect on the results of TMA-based studies. The main aim of this study was to evaluate the loss of informative cores having cut a given number of slices from a TMA block. A further objective was to investigate the effect in various subtypes of renal cell tumors and the detailed reasons for the loss of informative cores.

MATERIAL AND METHODS

A TMA was constructed from renal tumor specimens (n=461). The cause and rate of exclusion were evaluated in the first slice (FS) and last slice (LS) (i.e. the 40th) cut from the TMA blocks. Furthermore, the overall case loss under the assumptions that only one, two or three cores per case were punched was extrapolated.

RESULTS

Sarcomatoid and papillary renal cell carcinomas showed the highest overall exclusion rate. Irrespective of the type of tumor, however, the case loss was approximately tripled from FS to LS. Furthermore, extrapolation showed that a reduction in the number of cores punched per case, for example by one, would further double the number of cases lost. Reasons for exclusion were mainly as follows: core loss; <25% tumorous tissue per core; core folding; and core with necrotic area.

CONCLUSION

This study shows that punching at least three to four cores per case is advisable when constructing TMAs from oncocytoma and renal cell carcinoma specimens, and that the type of tumor has an effect on the cause and rate of core exclusion.

Lornoxicam characteristically modulates cerebral pain-processing in human volunteers: a functional magnetic resonance imaging study

BACKGROUND

Lornoxicam like other non-steroidal anti-inflammatory drugs (NSAIDs) is widely used for postoperative pain therapy. Evaluation of the effect of lornoxicam on cerebral processing of surgical pain was thus the aim of the present functional magnetic resonance imaging (fMRI) study.

METHODS

An fMRI-compatible pain model that mimics surgical pain was used to induce pain rated 4-5 on a visual analogue scale (VAS) at the anterior margin of the right tibia in volunteers (n=22) after i.v. administration of saline (n=11) or lornoxicam (0.1 mg kg(-1)) (n=11).

RESULTS

Lornoxicam, which significantly reduced pain sensation [VAS: mean (sd) 4.6 (0.7) vs 1.2 (1.5)], completely suppressed pain-induced activation in the SII/operculum, anterior cingulate cortex, insula, parietal (inferior), prefrontal (inferior, medial), temporal (inferior, medial/superior) lobe, cerebellum, and contralateral (e.g. left-sided) postcentral gyrus (SI). Only the hippocampus and the contralateral superior parietal lobe (BA 7) were activated.

CONCLUSIONS

As compared with saline, lornoxicam typically suppressed pain-induced brain activation in all regions except the hippocampus. Furthermore, de novo activation was found in the contralateral, superior parietal lobe (BA 7).

PTEN expression in renal cell carcinoma and oncocytoma and prognosis

AIMS

Deletion or inactivation of the tumour suppressor gene PTEN (phosphatase and tensin homologue deleted from chromosome 10) contributes to tumorigenesis in a variety of human carcinomas. The present study evaluated PTEN expression in renal cell carcinomas and oncocytomas.

METHODS

A tissue microarray from 493 specimens including renal cell carcinomas (n = 440), oncocytomas (n = 21) and tumour-negative renal tissue (n = 32) from patients (n = 461) was incubated with an anti-PTEN antibody for subsequent analysis of PTEN expression. Furthermore, the effect of PTEN expression on the survival of renal carcinoma patients was evaluated.

RESULTS

Renal cell carcinomas, and even more pronouncedly oncocytomas, expressed PTEN predominantly in the cytoplasm. In contrast to oncocytomas, PTEN expression was typically decreased in renal cell carcinoma subtypes. PTEN expression in sarcomatoid renal cell carcinomas was comparable to that in non-sarcomatoid subtypes. The PTEN expression pattern had no significant influence on prognosis.

CONCLUSIONS

Renal tumours (renal cell carcinomas and oncocytomas) express PTEN protein predominantly in the cytoplasm. A reduction in PTEN expression appears to be an early step in renal cell carcinogenesis. However, the PTEN expression pattern of renal cell carcinomas apparently is not prognostic for patient survival.

Using an automated emboli detection device in a porcine cardiopulmonary bypass (CPB) model: feasibility and considerations

The significant risk of cerebral embolism during cardiopulmonary bypass (CPB) makes monitoring of embolic events advisable already when developing new operation and coagulation management strategies for example in CPB animal models. The present study therefore evaluated in a porcine CPB model the feasibility of bilateral epicarotid Doppler signal recording and the quality of manual or automatic emboli detection. A total of 42 recordings (e.g. right carotid artery (n = 20), left carotid artery (n = 22)) were evaluated. The frequency of emboli counts was comparable for both carotid arteries. Automatic emboli detection, however, found significantly more embolic events per pig than did post-hoc manual off-line analysis of the recordings (172 +/- 217 vs. 13 +/-10). None of the brains, however, showed any emboli or infarction area either in cross-examination or in histological evaluation. In conclusion, the present study showed the feasibility of using an epicarotid Doppler device for bilateral emboli detection in a porcine CPB model. Automatic on-line emboli detection, however, reported more embolic events than did post hoc, off-line manual analysis. Possible reasons for this discrepancy are discussed.

Does caffeine modulate verbal working memory processes? An fMRI study

To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memory task, we examined blood oxygenation level-dependent regional brain activity in 15 healthy right-handed males. The subjects, all moderate caffeine consumers, underwent two scanning sessions on a 1.5-T MR-Scanner separated by a 24- to 48-h interval. Each participant received either placebo or 100 mg caffeine 20 min prior to the performance of the working memory task in blinded crossover fashion. The study was implemented as a blocked-design. Analysis was performed using SPM2. In both conditions, the characteristic working memory network of frontoparietal cortical activation including the precuneus and the anterior cingulate could be shown. In comparison to placebo, caffeine caused an increased response in the bilateral medial frontopolar cortex (BA 10), extending to the right anterior cingulate cortex (BA 32). These results suggest that caffeine modulates neuronal activity as evidenced by fMRI signal changes in a network of brain areas associated with executive and attentional functions during working memory processes.

Robotic totally endoscopic double-vessel bypass grafting: a further step toward closed-chest surgical treatment of multivessel coronary artery disease

BACKGROUND

After the introduction of robotic technology into the heart surgery armamentarium the performance of totally endoscopic coronary artery bypass grafting (TECAB) has become a reality. During the first years of development, the majority of TECAB cases were restricted to single-vessel disease, and the development of multivessel procedures is desirable. We report on a preliminary series of totally endoscopic double-vessel coronary artery bypass grafting.

METHODS

From 2004 to 2006, 10 patients underwent endoscopic placement of the right internal mammary artery (RIMA) to the left anterior descending artery (LAD) in combination with left internal mammary artery (LIMA) grafting to an obtuse marginal (OM) branch. Indications for the operation were isolated left main disease or left main equivalents. All procedures were performed using the daVinci telemanipulation system, remote-access perfusion, and aortic balloon endo-occlusion.

RESULTS

Seven of the 10 interventions were completed endoscopically, and 3 patients were converted to sternotomy. RIMA takedown time was 40 minutes (range, 29-49 minutes); LIMA takedown time was 38 minutes (range, 29-48 minutes). LAD and OM anastomotic times were 23 minutes (range, 14-53 minutes) and 38 minutes (range, 29-48 minutes), respectively. Total TECAB time was 477 minutes (range, 385-545 minutes). Median ventilation time was 15 hours (range, 6-40 hours), median intensive care unit stay was 41 hours (range, 15-141 hours), and patients were discharged after a median of 7 days (range, 5-22 days). No major adverse cardiac or cerebrovascular events occurred during short-term follow-up.

CONCLUSION

Totally endoscopic double-vessel coronary artery bypass grafting on the arrested heart is a reproducible procedure. This intervention offers maximal preservation of patient integrity, but the long operative times need to be investigated.

The association between local atherosclerosis and prostate cancer

OBJECTIVE

To morphometrically compare local atherosclerotic changes in cancerous prostate with those in noncancerous prostate specimens, as epidemiological studies report a positive association between the prevalence of general atherosclerosis and prostate cancer.

MATERIALS AND METHODS

The intima-to-media-ratio (IMR) of 538 prostate capsular tissue arteries was measured in 50 prostate cancer-positive and 29 prostate cancer-negative specimens (including 26 with benign prostatic hyperplasia and three with normal prostatic tissue).

RESULTS

An IMR of >1 was significantly associated with prostate cancer and a greater risk of prostate cancer (odds ratio 2.28). The IMR was >1 in cancer-positive specimens about twice as often as in cancer-negative tissue.

CONCLUSION

Local atherosclerosis (measured by the IMR) was more pronounced in prostate cancer-positive than in prostate cancer-negative specimens. The results support the view that men with local atherosclerotic lesions are at higher risk of prostate cancer.

Robotically assisted totally endoscopic atrial septal defect repair: insights from operative times, learning curves, and clinical outcome

BACKGROUND

Remote access perfusion and robotics have enabled totally endoscopic closure of atrial septal defect and patent foramen ovale. The aim of this study was to address learning curve issues of totally endoscopic atrial septal defect repair on the basis of a single-center experience and to investigate whether long cardiopulmonary bypass and aortic occlusion times influence intraoperative and postoperative outcomes.

METHODS

Seventeen patients (median age, 35 years; range, 16 to 55 years) underwent totally endoscopic atrial septal defect repair using remote access perfusion and robotic technology (da Vinci telemanipulation system). Learning curves were assessed by means of regression analysis with logarithmic curve fit. The effect of operative variables on clinical outcome was analyzed by linear regression using the Spearman's rho coefficient.

RESULTS

No operative mortality or serious surgical complications were observed. No residual shunt was detected at intraoperative or postoperative echocardiography. Significant learning curves were noted for total operative time: y(min) = 406 - 49 ln(x) (r2 = 0.725; p = 0.002); cardiopulmonary bypass time: y(min) = 225 - 42 ln(x) (r2 = 0.699; p = 0.003); and aortic occlusion time: y(min) = 117 - 25 ln(x) (r2 = 0.517; p = 0.04), x = number of procedures. Median ventilation time, intensive care unit stay, and hospital length of stay were 7 hours (range, 2 to 19 hours), 26 hours (range, 15 to 120 hours), and 8 days (range, 5 to 14 days), respectively. No correlation was detected between cardiopulmonary bypass time and intubation time (r2 = 0.283; p = 0.326), intensive care unit stay (r2 = -0.138; p = 0.639), or total length of stay (r2 = 0.013; p = 0.962).

CONCLUSIONS

Totally endoscopic atrial septal defect repair can be performed safely, and learning curves for operative times are steep. Longer cardiopulmonary bypass times had no negative impact on intraoperative and postoperative outcome.

Bipolar Anastomosis Technique (BAT) Enables "Fast-To-Do", High-Quality Venous End-To-End Anastomosis in a New Vascular Model

The interrupted suture technique is most commonly used for microsurgical venous anastomosis. Needle-stitch trauma and intraluminal suture, however, potentially cause vascular wall damage, thrombosis, intimal hyperplasia or even stenosis. Therefore, the present study aimed to show the feasibility and reliability of a modified cuff technique (bipolar anastomosis technique (BAT)) for venous end-to-end anastomosis in a new chicken throat vascular model. In ex vivo experiments, freshly resected chicken jugular veins (N = 96) were used to find ideal BAT time to current settings for venous end-to-end anastomosis. Thereafter, the left jugular vein of chickens (N = 40) was dissected in vivo and subsequently anastomosed using BAT. The quality of anastomosis was evaluated by Doppler sonography immediately, at two hours and at two, six, 12, 16, and 29 weeks after surgery. Additional histological examination took place at two hours (N = 8) and at two (N = 6), six (N = 6), 12 (N = 6), 16 (N = 6) and 29 (N = 6) weeks after surgery. Immediately after surgery (N = 40) and at two hours (N = 38) venous anastomoses were found to be patent in Doppler sonography. Anastomotic rupture caused death in two animals within one hour after surgery. Thrombotic occlusion was found in one animal at six weeks after surgery. In the remaining animals (N = 37) only minimal stenosis which decreased to almost normal levels was sonographically found. The average time needed for anastomosis using BAT was less than two minutes. BAT allows fast venous end-to-end anastomosis in a chicken throat vascular model.

Technical challenges in totally endoscopic robotic coronary artery bypass grafting

OBJECTIVE

Robotic technology is a prerequisite for performance of totally endoscopic coronary artery bypass grafting. During the implementation phase of totally endoscopic coronary artery bypass, surgeon-related technical difficulties might be encountered. It was the aim of this study to assess the incidence of these challenges, to find risk factors, and to describe clinical results associated with technical errors.

METHODS

From October 2001 through October 2004, 40 patients received robotically assisted totally endoscopic left internal thoracic artery grafts to the left anterior descending coronary artery system with the da Vinci telemanipulation device. All patients underwent remote access cardiopulmonary bypass perfusion through groin access, and all anastomoses were performed on the arrested heart.

RESULTS

Undesirable technical events of various grades occurred in 20 (50%) of 40 patients: bleeding from a port hole in 3 (8%), left internal thoracic artery damage in 3 (8%), epicardial lesion in 3 (8%), remote access perfusion problems in 9 (23%), bleeding from the anastomosis in 4 (10%), and anastomotic stenosis in 2 (5%). There was no hospital mortality. The following differences were noted between patients without technical difficulties (group 1) and those in whom problems occurred (group 2): total operative time of 314 minutes (260-540 minutes) versus 418 minutes (270-690 minutes; P = .007), ventilation time of 6 hours (0-26 hours) versus 14 hours (0-278 hours; P = .004), intensive care unit stay of 20 hours (11-70 hours) versus 44 hours (16-336 hours; P=.183), hospital stay of 7 days (4-13 days) versus 8 days (5-21 days; P = .038), and cumulative freedom from angina at 36 months of 93% versus 100% (P = .317).

CONCLUSION

We conclude that technical difficulties during totally endoscopic coronary artery bypass grafting translate into markedly increased operative time, moderately prolonged postoperative ventilation time, and slightly increased hospital stay. Short-term survival and freedom from angina, however, do not seem to be compromised.

Perforated Meckel's diverticulum presenting as a gastrointestinal stromal tumor: a case report

Tumors and perforation of Meckel's diverticulum are rare manifestations. A gastrointestinal stromal tumor in a Meckel's diverticulum causing perforation and subsequent peritonitis in a 75-year-old man is presented. The literature on tumors in Meckel's diverticulum is extensively reviewed and discussed.

Normal values for thrombelastography (ROTEM) and selected coagulation parameters in porcine blood

The pig is a suitable animal model for researching blood coagulation and fibrinolysis. The present study therefore aimed to investigate in porcine blood the applicability of commercially available tests of coagulation and thrombelastography (ROTEM) and above all to determine normal values for coagulation parameters (e.g. prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin-antithrombin complexes (TAT), fibrinogen, antithrombin III (AT III), D-dimers, protein C). Except for the FibTEM and aPTT tests, all commercially available coagulation tests used were fully applicable for porcine blood. Normal values and reference intervals for porcine blood are given. As compared to the human reference intervals for the coagulation parameters investigated, porcine blood was found to be hypercoagulable.

Incidence of lower thoracic ligamentum flavum midline gaps † †Presented in abstract form at the IARS 78th Clinical and Scientific Congress, Tampa Bay, Florida, USA, 2004

BACKGROUND

Lower thoracic epidural anaesthesia and analgesia (EDA) has gained increasing importance in perioperative pain therapy. The loss-of-resistance technique used to identify the epidural space is thought to rely on the penetration of the ligamentum flavum. Investigations at the cervical and lumbar regions have demonstrated that the ligamentum flavum frequently exhibits incomplete fusion at different vertebral levels. Therefore, the aim of this study was to directly investigate the incidence of lower thoracic ligamentum flavum midline gaps in embalmed cadavers.

METHODS

Vertebral column specimens were obtained from 47 human cadavers. Ligamentum flavum midline gaps were recorded between the vertebral levels T6 and L1.

RESULTS

The incidence of midline gaps/number of viable specimens at the following levels was: T6-7: 2/45 (4.4%), T7-8: 1/47 (2.1%), T8-9: 2/45 (4.4%), T9-10: 7/39 (17.9%), T10-11: 12/34 (35.2%), T11-12: 10/35 (28.5%), T12/L1: 6/38 (15.8%).

CONCLUSIONS

In the present study we have determined the frequency of lower thoracic ligamentum flavum midline gaps. Gaps are less frequent than at cervical levels, but more frequent than at lumbar levels. Peak incidence was found in the region between T10 and T12. Using a strict midline approach, one cannot therefore rely on the ligamentum flavum to impede entering the epidural space in all patients.

Robotic Totally Endoscopic Coronary Artery Bypass and Catheter Based Coronary Intervention in One Operative Session

A 56-year-old male patient underwent robotically assisted totally endoscopic left internal mammary artery (LIMA) to left anterior descending artery (LAD) grafting. After protamine administration complete heart block developed in the patient. On intraoperative angiography the LIMA to LAD graft was perfectly patent but an acute occlusion of the right coronary artery (RCA) was noted. We performed an immediate on table percutaneous coronary angioplasty and stent placement to the RCA. The heart regained sinus rhythm and the wall motion abnormalities on the back wall of the heart resolved. No clinical symptoms indicating ongoing myocardial ischemia were noted postoperatively. This case demonstrates that a hybrid procedure of robotic totally endoscopic coronary artery bypass grafting and catheter based coronary intervention is feasible in one simultaneous session.