A Touchless system for image visualization during surgery: preliminary experience in clinical settings.

Today clinicians may access large medical datasets, but very few systems have been designed to allow a practical and efficient exploration of data directly in critical medical environments such as operating rooms (OR). This work aims to assess during tests in laboratory and clinical settings a Surgery Touchless System (STS). This system allows clinicians to interact with medical images by using two different approaches: a gesture recognition and a voice recognition based system. These two methods are based on the use of a Microsoft Kinect and of a selective microphone, respectively. The STS allows navigating in a specifically designed interface, to perform several tasks, among others, to manipulate biomedical images. In this article, we assessed both the recognitions approaches in laboratory with 5 users. In addition, the STS was tested using only the voice-based recognition approach in clinical settings. The assessment was performed during three procedures by two interventionalradiologists. The five volunteers and the 2 radiologists filled two questionnaires to assess the system. The system usability was positively evaluated in laboratory tests. From clinical trials emerged that the STS was considered safe and useful by both the radiologists: they used the system an averaged number of times of 10 and 15 for patients, and found the system useful. These promising results allow considering this system useful for providing information not otherwise accessible and limiting the impact of human error during the operation. Future work will be focused on the use of the STS on a high number and different types of procedure.

Ex vivo animal-model assessment of a non-invasive system for loss of resistance detection during epidural blockade.

During recent decades epidural analgesia has gained widespread recognition in many applications. In this complex procedure, anaesthetist uses a specific needle to inject anesthetic into the epidural space. It is crucial the appropriate insertion of the needle through inhomogeneous tissues placed between the skin and the epidural space to minimize anesthetic-related complications (e.g., nausea, headache, and dural puncture). Usually, anaesthetists perform the procedure without any supporting tools, and stop pushing the syringe when they sense a loss of resistance (LOR). This phenomenon is caused by the physical properties of the epidural space: the needle breaks the ligamentum flavum and reaches the epidural space, in this stage the anaesthetist perceives a LOR because the epidural space is much softer than the ligamentum flavum. To support the clinician in this maneuver we designed a non-invasive system able to detect the LOR by measuring the pressure exerted on the syringe plunger to push the needle up to the epidural space. In a previous work we described the system and its assessment during in vitro tests. This work aims at assessing the feasibility of the system for LOR detection on a more realistic model (ex vivo pig model). The system was assessed by analyzing: its ability to hold a constant value (saturation condition) during the insertion of the needle, and its ability to detect the entrance within the epidural space by a decrease of the system's output. Lastly, the anaesthetist was asked to assess how the ex vivo procedure mimics a clinical scenario. The system reached the saturation condition during the needle insertion; this feature is critical to avoid false positive during the procedure. However, it was not easy to detect the entrance within the epidural space due to its small volume in the animal model. Lastly, the practitioner found real the model, and performed the procedures in a conventional manner because the system did not influence his actions.

A cost-effective, non-invasive system for pressure monitoring during epidural needle insertion: Design, development and bench tests.

Epidural blockade procedures have gained large acceptance during last decades. However, the insertion of the needle during epidural blockade procedures is challenging, and there is an increasing alarming risk in accidental dural puncture. One of the most popular approaches to minimize the mentioned risk is to detect the epidural space on the base of the loss of resistance (LOR) during the epidural needle insertion. The aim of this paper is to illustrate an innovative and non-invasive system able to monitor the pressure exerted during the epidural blockade procedure in order to detect the LOR. The system is based on a Force Sensing Resistor (FSR) sensor arranged on the top of the syringe's plunger. Such a sensor is able to register the resistance opposed to the needle by the different tissues transducing the pressure exerted on the plunger into a change of an electrical resistance. Hence, on the base of a peculiar algorithm, the system automatically detects LOR providing visual and acoustic feedbacks to the operator improving the safety of the procedure. Experiments have been performed to characterize the measurement device and to validate the whole system. Notice that the proposed solution is able to perform an effective detection of the LOR.

Dynamic contrast-enhanced MR evaluation of prostate cancer before and after endorectal high-intensity focused ultrasound.

PURPOSE: The authors sought to determine the diagnostic performance of dynamic contrast-enhanced magnetic resonance (DCE-MR) imaging in the evaluation of prostate cancer before and after transrectal high-intensity focused ultrasound (HIFU) treatment. MATERIALS AND METHODS: We analysed 25 patients with prostate cancer. The prostate-specific antigen (PSA) value was evaluated 1, 4 and 6 months after treatment. DCE-MR imaging was performed the day prior to and 1, 4 and 6 months after HIFU treatment. Transrectal prostate biopsies were obtained at the time of diagnosis and 6 months after treatment. RESULTS: Before treatment, intraglandular lesions were considered to be potential sites of neoplasm and subsequently confirmed as sites of prostate adenocarcinoma in all 25 patients based on prostatespecific antigen (PSA) values and histological examinations (rho=1; p<0.001). Using histology as the gold standard, DCE-MR imaging displayed 100% sensitivity, 100% specificity, 100% positive predictive value and 100% negative predictive value before treatment. After HIFU treatment, DCE-MR imaging showed 100% sensitivity and 96% specificity. CONCLUSIONS: DCE-MR imaging can be used to visualise prostate adenocarcinoma. Several morphological and postgadolinium modifications in the follow-up DCE-MR images after HIFU treatment were also observed.

Differentiation of normal and neoplastic bone tissue in dynamic gadolinium-enhanced magnetic resonance imaging: validation of a semiautomated technique.

PURPOSE: This study was undertaken to clinically validate the accuracy of a semiautomated software tool for analysing the enhancement curve in focal malignant bone lesions. MATERIALS AND METHODS: Twenty-three patients affected by cancer with malignant focal bone lesions underwent dynamic gadolinium-enhanced magnetic resonance (MR) imaging using the following protocol: T1-weighted turbo spin-echo sequences (time to repeat [TR] 600 ms, time to echo [TE] 8.6 ms, field of view [FOV] 40x40 cm) before and after intravenous injection of gadolinium-containing contrast agent. Image postprocessing was performed using the software DyCoH. Each region of interest (5x5 pixels), drawn to include the area of the lesion with the highest values of the area under the curve map, was analysed to obtain time-intensity curves and relative perfusion parameters: time to peak (TTP), peak intensity (PI), slope (60-s slope), intensity at 60 s after contrast agent injection (60-s I) and final intensity (FI). RESULTS: Data were obtained by analysing 86 malignant lesions and 86 apparently normal bone regions. PI, 60-s slope, 60-s I and FI were significantly different between neoplastic and apparently normal (p<0.001) samples. Sensitivity, specificity and accuracy were, respectively, 94%, 93% and 94% at a PI threshold of 100 (signal-to-noise ratio), with positive and negative predictive values of 93% and 94%. At a threshold value of 0.85 for 60-s slope, sensitivity and specificity values were both 91%. CONCLUSIONS: The semiautomated technique we report appears to be accurate for identifying neoplastic tissue and for mapping perfusion parameters, with the added value of a consistent measurement of perfusion parameters on colour-coded maps.