Linear unmixing protocol for hyperspectral image fusion analysis applied to a case study of vegetal tissues.

Hyperspectral imaging (HSI) is a useful non-invasive technique that offers spatial and chemical information of samples. Often, different HSI techniques are used to obtain complementary information from the sample by combining different image modalities (Image Fusion). However, issues related to the different spatial resolution, sample orientation or area scanned among platforms need to be properly addressed. Unmixing methods are helpful to analyze and interpret the information of HSI related to each of the components contributing to the signal. Among those, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) offers very suitable features for image fusion, since it can easily cope with multiset structures formed by blocks of images coming from different samples and platforms and allows the use of optional and diverse constraints to adapt to the specific features of each HSI employed. In this work, a case study based on the investigation of cross-sections from rice leaves by Raman, synchrotron infrared and fluorescence imaging techniques is presented. HSI of these three different techniques are fused for the first time in a single data structure and analyzed by MCR-ALS. This example is challenging in nature and is particularly suitable to describe clearly the necessary steps required to perform unmixing in an image fusion context. Although this protocol is presented and applied to a study of vegetal tissues, it can be generally used in many other samples and combinations of imaging platforms.

Onsets of complications and revisions are not increased after simultaneous bilateral unicompartmental knee arthroplasty in comparison with unilateral procedures.

PURPOSE: The advantages of simultaneous bilateral procedures in joint arthroplasty have been widely described for in total joint replacements of both the hip and the knee. In contrast, unicompartmental knee arthroplasties, despite their effectiveness in pain relieving and functional improvement, are underinvestigated in these terms. The purpose of this study is to assess the possible benefits and risks of bilateral simultaneous knee replacements, in comparison with unilateral procedures. METHODS: A total of 567 surgery reports of bilateral simultaneous (220) or unilateral (347) unicompartmental knee arthroplasties were analysed to collect study parameters. Information like the onset of complications and need for revisions were recorded by phone interview (at least two years after surgery). All surgeries were performed by the same orthopaedic surgeon, assisted by the same anesthesiologist. RESULTS: Complication and revision rates, as well as the length of hospital stay were similar between the two study groups, while blood and haemoglobin losses, and consequently the use of transfusion of allogeneic and autologous blood units, were higher in the simultaneous bilateral group. CONCLUSIONS: Simultaneous bilateral unicompartmental knee arthroplasties could significantly reduce, if both joints are affected, the length of hospital stay and, therefore, patient management costs. At the same time, they do not lead to more frequent revisions or complications. The higher transfusion of allogeneic blood units could be reduced to unilateral surgery levels by the application of currently available protocols of autologous blood reinfusion.

Simultaneous bilateral total hip arthroplasties do not lead to higher complication or allogeneic transfusion rates compared to unilateral procedures.

PURPOSE: About 20 % of patients undergoing a primary total hip arthroplasty could undergo a second contralateral procedure within five years. The possibility to perform simultaneous bilateral hip replacements instead of two-stage surgery could reduce hospitalisation time and patient management costs, but concerns exist because of risks related to massive blood loss and possible increase in complication rates. The purpose of this study is to assess the veracity of these concerns. METHODS: Parameters like blood loss, transfused blood units, total hospital length of stay (surgical and rehabilitation) and presence of in-hospital complications were collected from surgery reports of two different groups of patients. The first group comprised patients undergoing simultaneous bilateral total hip arthroplasty (n = 63), while the second group consisted of patients undergoing unilateral surgery (n = 97). Occurrence of complications within six post-operative months was assessed by phone interview. RESULTS: No differences were observed in complication, revision and mortality rates between the study groups. On the contrary, blood loss was significantly higher in the bilateral group, but the application of appropriate transfusion protocols reduced the use of allogeneic blood transfusion to the levels recorded for unilateral patients. Moreover, the difference in length of hospital stay (about two days) between the two groups was not clinically relevant. CONCLUSIONS: Our data show that simultaneous bilateral procedures do not lead to higher complication or allogeneic transfusion rates in comparison to unilateral hip replacement, and that, in cases of bilateral disease, they could significantly reduce the total length of hospital stay and, therefore, patient management costs.