Secure and efficient health data management through multiple watermarking on medical images.

The landscape of healthcare delivery and medical data management has significantly changed over the last years, as a result of the significant advancements in information and communication technologies. Complementary and/or alternative solutions are needed to meet the new challenges, especially regarding security of the widely distributed sensitive medical information. Digital watermarking is a recently established research area with many applications; nevertheless, the potential of this technology to contribute value-added services to medical information management systems has only recently started to be realized by the research community. The paper presents a review of research efforts in the area of medical-oriented watermarking and proposes a wavelet-based multiple watermarking scheme; this scheme aims to address critical health information management issues, including origin and data authentication, protection of sensitive data, and image archiving and retrieval. In accordance with the strict limitations applying to medical images, the scheme allows the definition of a region of interest (ROI) whose diagnostic value is protected, since the only additional information embedded therein aims at integrity control. The robustness of the method is enhanced through a form of hybrid coding, which includes repetitive embedding of BCH encoded watermarks. The experimental results on different medical imaging modalities demonstrate the efficiency and transparency of the watermarking scheme.

An integrated computer supported acquisition, handling, and characterization system for pigmented skin lesions in dermatological images.

This paper describes an integrated prototype computer-based system for the characterization of skin digital images. The first stage includes an image acquisition arrangement designed for capturing skin images, under reproducible conditions. The system processes the captured images and performs unsupervised image segmentation and image registration utilizing an efficient algorithm based on the log-polar transform of the images' Fourier spectrum. Border- and color-based features, extracted from the digital images of skin lesions, were used to construct a classification module for the recognition of malignant melanoma versus dysplastic nevus. Different methods, drawn from the fields of artificial intelligence (neural networks) and statistical modeling (discriminant analysis), were used in order to find the best classification rules and to compare the results of different approaches to the problem.

Feasibility study of the use of similarity maps in the evaluation of oncological dynamic positron emission tomography images.

A preliminary study is presented on the potential role of similarity mapping (SM) in the evaluation of oncological dynamic 18F-fluorodeoxyglucose positron emission tomography studies, mainly in lesion localisation and detectability. Similarity maps were calculated using previously described (correlation coefficient (COR) and normalised correlation coefficient (NCOR)) and newly introduced similarity measures (sum of squares coefficient (SSQ), squared sum coefficient (SQS), sum of cubes coefficient (SC) and cubed sum coefficient (CS)). The results were evaluated using simulated and clinical data. The study revealed that the best-suited similarity measure for such applications was the CS similarity coefficient, which provided the best parametric images, delineating structures of interest and supporting the visual interpretation of data sets. It was shown that SM and standardised uptake value (SUV) images had comparable diagnostic performance, although SM was able to offer additional time-related information in a single image. For the case of colorectal recurrences (17 cases), the measured contrast values for the CS and SUV images were 2.36 +/- 0.47 and 4.12 +/- 0.42, respectively, whereas, for three cases of giant cell tumours, these values were 11.6 +/- 2.1 and 11.9 +/- 1.8, respectively.

Conformational studies on a diastereoisomeric pair of tricyclic nonclassical cannabinoids by NMR spectroscopy and computer molecular modeling.

Among the nonclassical cannabinoids, CP-55,244 (4), which incorporates an axial 14 beta-hydroxymethyl group, is pharmacologically 30 times more potent than its prototype CP-47,497 (2) and 300 times more potent than delta 9-THC (1). It has a high degree of stereoselectivity (about 120:1) with respect to its diastereoisomer, CP-97,587 (5), which differs structurally by having the 14-hydroxymethyl group equatorial. Conformational studies of 4 and 5 were carried out using 2D NMR spectroscopy and molecular modeling in order to define and compare the similarities and differences between them. Specific structural features of interest are the conformation of the 1',1'-dimethylheptyl (DMH) side chain, the conformation of the cyclohexyl rings, the orientation of the phenolic ring (A ring) relative to the cyclohexyl ring (C ring), and the orientation of the hydroxymethyl group as well as the formation of intramolecular hydrogen bonding. Our results show that the conformations of the phenolic hydroxyl (Ph-OH) and DMH side chain for 4 are similar to those of 2. The proton of the phenolic hydroxyl is pointing away from the C ring while the DMH chain randomly adopts one of four dynamically averaged conformers in which it is almost perpendicular to the plane of the aromatic ring. The relative orientation of the A and C rings is such that the two rings interconvert between two low-energy conformations. Compound 5 prefers the conformer with the Ph-OH pointing toward the alpha-face of the cyclohexyl ring, while for 4, there is an increased preference for the conformer where the Ph-OH is directed toward the beta face. This may be due to intramolecular H-bonding between the Ph-OH and the axial 14 beta-hydroxymethyl group of 4 that stabilizes this conformation. Hydrogen bonding between the Ph-OH and the equatorial-14 alpha-hydroxymethyl of 5 was not detected. Thus, the orientation of the aliphatic hydroxyl group with respect to the D ring in 4 and 5 may play an important role with regard to the pharmacophoric requirements of the two analogs for the cannabinoid receptor and provide an explanation for the observed differences in their biological properties.

Multi-purpose HealthCare Telemedicine Systems with mobile communication link support.

The provision of effective emergency telemedicine and home monitoring solutions are the major fields of interest discussed in this study. Ambulances, Rural Health Centers (RHC) or other remote health location such as Ships navigating in wide seas are common examples of possible emergency sites, while critical care telemetry and telemedicine home follow-ups are important issues of telemonitoring. In order to support the above different growing application fields we created a combined real-time and store and forward facility that consists of a base unit and a telemedicine (mobile) unit. This integrated system: can be used when handling emergency cases in ambulances, RHC or ships by using a mobile telemedicine unit at the emergency site and a base unit at the hospital-expert's site, enhances intensive health care provision by giving a mobile base unit to the ICU doctor while the telemedicine unit remains at the ICU patient site and enables home telemonitoring, by installing the telemedicine unit at the patient's home while the base unit remains at the physician's office or hospital. The system allows the transmission of vital biosignals (3-12 lead ECG, SPO2, NIBP, IBP, Temp) and still images of the patient. The transmission is performed through GSM mobile telecommunication network, through satellite links (where GSM is not available) or through Plain Old Telephony Systems (POTS) where available. Using this device a specialist doctor can telematically "move" to the patient's site and instruct unspecialized personnel when handling an emergency or telemonitoring case. Due to the need of storing and archiving of all data interchanged during the telemedicine sessions, we have equipped the consultation site with a multimedia database able to store and manage the data collected by the system. The performance of the system has been technically tested over several telecommunication means; in addition the system has been clinically validated in three different countries using a standardized medical protocol.

New hybrid stochastic-deterministic technique for fast registration of dermatological images.

Digital image processing in the medical field has become very popular in recent years owing to the significant advantages it offers over conventional techniques of visual or analogue image analysis. One of the most significant aspects in medical image processing has been that of image registration, which deals with the task of registering two images taken under different conditions. Image registration is considered an important issue in the field of dermatology, as pictures of a lesion taken in different periods need to be compared and quantitatively analysed. A hybrid image registration scheme was developed and evaluated for dermatological applications. The method splits the parameter estimation problem into two, with a combination of deterministic and iterative estimation techniques. The scaling and rotation parameters are estimated using a cross-correlation of image invariant image descriptors algorithm, whereas the two translation parameters are estimated with a non-parametric similarity criterion and a hill-climbing optimisation scheme. The efficacy of the method has been validated for the registration and comparison of malignant melanoma images. Determination of rotation and scaling parameters was performed using the log-polar transformation technique, which proved to be very accurate, even when high rotation and scaling values were imposed. Deviations for the rotation parameter estimations were less than 0.5%, whereas, for the scaling factor, differences were on average less than 2.5%, with a maximum difference estimated to be 4.5%. Translation parameter estimation was performed using integer similarity measures namely the stochastic sign change, the deterministic sign change (DSC) and the window value range, the performance of which has been assessed and, in all cases, was found to be highly effective. A novel hill-climbing optimisation algorithm has been proposed and, in combination with the DSC similarity criterion, was evaluated and proved to successfully estimate translation parameters. Thus the proposed hybrid registration technique can successfully estimate problem parameters in a time-efficient manner.

Designing and implementing the transition to a fully digital hospital.

The increase in the number of examinations performed in modern healthcare institutions in conjunction with the range of imaging modalities available today have resulted in a tremendous increase in the number of medical images generated and has made the need for a dedicated system able to acquire, distribute, and store medical image data very attractive. Within the framework of the Hellenic R&D program, we have designed and implemented a picture archiving and communication system for a high-tech cardiosurgery hospital in Greece. The system is able to handle in a digital form images produced from ultrasound, X-ray angiography, gamma-camera, chest X-rays, as well as electrocardiogram signals. Based on the adoption of an open architecture highly relying on the DICOM standard, the system enables the smooth transition from the existing procedures to a fully digital operation mode and the integration of all existing medical equipment to the new central archiving system.

A novel emergency telemedicine system based on wireless communication technology--AMBULANCE.

Recent studies conclude that early and specialized prehospital management contributes to emergency case survival. We have developed a portable medical device that allows telediagnosis, long distance support, and teleconsultation of mobile healthcare providers by expert physicians. The device allows the transmission of vital biosignals and still images of the patient from the emergency site to the consultation site using the GSM mobile telephony network. The device can telematically "bring" an expert specialist doctor at the site of the medical emergency, allow him/her to evaluate patient data, and issue directions to the emergency personnel on treatment procedures until the patient is brought to be hospital. Legal reasons mandated the inclusion at the consultation site of a multimedia database able to store and manage the data collected by the system. The performance of the system has been validated in four different countries using a controlled medical protocol and a set of 100 patients per country treated has been collected and analyzed.

A PC data-base with analytical applications for evoked potentials.

Visual Evoked Potentials (VEPs) are gaining ground in the research for diagnosis of neurological disorders and visual defects, as a non-invasive diagnostic tool. Yet, the methods used towards these goals are not universal and far from able to provide a common ground among researchers in collecting, analyzing and comparing their results. This paper is an attempt to close the gap. We have developed a PC data-base and a set of analysis programs with graphic capabilities, frequency analysis, as well as an objective way of describing the signals obtained during VEP experiments.

Effect of wavelet compression on data transmission in a multipurpose wireless telemedicine system.

We have developed a novel emergency telemedicine system which allows the transmission of physiological data (electrocardiogram, oximetry, blood pressure and temperature) and still images of the patient. The transmission is performed through wireless links using either GSM mobile phones or satellite. Because of the low bandwidth available through these links, data compression is required to allow realtime transmission of electrocardiographic (ECG) data. A new integrated design approach for an optimal zonal wavelet compression (OZWC) method was implemented for the ECG data. The performance of the mobile system with compressed ECG data segments was evaluated in terms of the percentage root-mean-square difference and visual inspection. The optimum wavelet algorithm achieved a maximum compression ratio of 18:1 with low distortion.

Design and development of a multimedia database for emergency telemedicine.

Recent studies conclude that early and specialised pre-hospital patient management contributes to emergency cases survival. Recent developments in telecommunication and medical informatics by means of telemedicine can be extremely useful to accomplish such tasks in a cost-effective manner. Along that direction, we have designed a portable device for emergency telemedicine. This device is able to telematically "bring" the expert doctor at the emergency site, have him perform an accurate diagnosis, and subsequently direct the Emergency Medical Technicians on how to treat the patient until he arrives to the hospital. The need for storing and archiving all data being interchanged during the telemedicine sessions is very crucial for clinical, legal and administrative purposes. For this, we have developed a multimedia database able to store and manage the data collected by the AMBULANCE system. The database was equipped with a user-friendly graphical interface to enable use from computer naive users. Furthermore, the database has the possibility to display, in an standard way, ECG's, X-ray, CT and MRI images. The application is password protected with a three-level hierarchy access for users with different privileges. The scope of this application is to enhance the capabilities of the doctor on duty for a more precise and prompt diagnosis. The application has the ability to store audio files related to each emergency case and still images of the scene. Finally, this database can become a useful multimedia tool which will work together with the AMBULANCE portable device, the HIS and the PACS of the hospital. The system has been validated in selected non-critical cases and proved to be functional and successful in enhancing the ability of the doctor's on duty for prompt and accurate diagnosis and specialised pre-hospital treatment.

XML and the VITAL standard: the document-oriented approach for open telemedicine applications.

This paper describes an effort to create a common, document-oriented architecture for the interchange of medical data in healthcare telemedicine applications. Key components are: The VITAL standard specifying a common (medical device independent) representation of Vital Signs Information and the Extensible Markup Language (XML) specifying the document specifications form, an architecture that, in aggregate, define the semantics and structural constraints necessary for the exchange of vital signs and related medical data. The modelling and design technique for the described application has been the Unified Modelling Language (UML). The XMI (XML Metadata Interchange Format) of the Object Management Group (OMG) provided the meta-model for this application, for sharing objects using XML, via the transfer of the application's UML model to XML documents and DTDs.

An augmented reality system for health care provision via telematics support.

We are developing a prototype portable health care support device for Emergency Telemedicine. This device can telematically "bring" a specialist doctor at the site of a medical emergency, allow him to evaluate patient data and issue directions to the emergency personnel on treatment procedures until the patient is brought to hospital. The portable device is carried by a paramedic technician in "wearable" form, allowing the technician to perform his normal duties while communicating with the specialist at the hospital site. This augmented reality system allows for maximum utilisation of available resources and offers a complete, practical solution for increasing survival rates before and during the transportation of accident victims to hospital.

Mobile Medical Data (MOMEDA)--a Personalized Medical Information System.

MOMEDA is a two-years project supported by the European Commission (Telematics Applications Programme of DGXIII--Health Care Sector). The main objectives of the project are the development of a compact personal information terminal for hospital and home care environments that could be used by patients and a demonstrator that allows the consulting physician to access electronic patient record data from outside the hospital, using a hand held companion device connected to GSM network. Special attention is paid to a Personalized Medical Information System (PMIS) which will allow patients to access customized disease-specific information material that will enable them to fully understand in a simple and constructive form what their medical problem is, what the planned procedures are, what lifestyle they should follow during and after their hospitalization, thus becoming more qualified partners in the recovery process. Considering the fact that in most cases informed and educated patients are usually satisfied patients when the treatment is finished, patient satisfaction can be also accomplished. The design considerations for the PMIS system are presented and the implementation is discussed.

Vital signs monitoring from home with open systems.

This study investigates the applicability of a novel codification scheme based on two healthcare informatics standards (namely the VITAL (ENV 13734) and DICOM Sup. 30 Waveform Interchange) in addressing the robust interchange of waveform and medical data in remote healthcare applications. To further address system validation and clinical acceptance issues, pilots were set-up between home-monitoring stations and a hospital-based telemedicine consultation center. The pilots focused in assessing applicability, technical feasibility and performance of the proposed codification scheme based on the two standards. This paper presents the system and services requirements as studied for a home-care application, the design goals for the preservation of security stature, the practical issues of validation and the results of integrating these codification schemes into a commercial patient connected device.

ISWLS: novel algorithm for image reconstruction in PET.

The purpose of this study is to introduce a novel empirical iterative algorithm for medical image reconstruction, under the short name ISWLS (image space weighted least squares), which is expected to have image space reconstruction algorithm (ISRA) properties in noise manipulation and weighted least-squares (WLS) acceleration of the reconstruction process. We used phantom data from a prototype small-animal positron emission tomography system and the methods presented here are applied to 2-D sinograms. Further, we assess the performance of the new algorithm by comparing it to the simultaneous version of algebraic reconstruction technique (ART), simultaneous algebraic reconstruction technique (SART), to expectation maximization maximum likelihood (EM-ML), ISRA, and WLS. All algorithms are compared in terms of cross-correlation coefficient, reconstruction time, and contrast-to-noise ratios (CNRs). As it turns out, ISWLS presents higher CNRs than EM-ML, ISRA, and SART for objects of different sizes. Also, ISWLS shows similar performance to WLS during the first iterations but it has better noise manipulation. Finally, ordered subsets ISWLS (OS-ISWLS), the OS version of ISWLS, shows its best performance between the first six-nine iterations. Its behavior seems to be a compromise between OS-ISRA and OS-WLS.

Color based texture--classification of hysteroscopy images of the endometrium.

The objective of this study was to develop a CAD system for the classification of hysteroscopy images of the endometrium based on color texture analysis for the early detection of gynaecological cancer. A total of 416 Regions of Interest (ROIs) of the endometrium were extracted (208 normal and 208 abnormal) from 40 subjects. RGB images were gamma corrected and were converted to the HSV and YCrCb color systems. The following texture features were extracted for each channel of the RGB, HSV, and YCrCb systems: (i) Statistical Features, (ii) Spatial Gray Level Dependence Matrices and (iii) Gray Level Difference Statistics. The PNN statistical learning and SVM neural network classifiers were also investigated for classifying normal and abnormal ROIs. Results show that there is significant difference (using the Wilcoxon Rank Sum Test at a=0.05) between the texture features of normal and abnormal ROIs of the endometrium. Abnormal ROIs had higher gray scale median, variance, entropy and contrast and lower gray scale median and homogeneity values when compared to the normal ROIs. The highest percentage of correct classifications score was 79% and was achieved for the SVM models trained with the SF and GLDS features for differentiating between normal and abnormal ROIs. Concluding, a CAD system based on texture analysis and SVM models can be used to classify normal and abnormal endometrium tissue. Further work is needed to validate the system in more cases and organs.

Multiple digital watermarking applied to medical imaging.

Beyond its already established wide range of applications, digital watermarking has recently started to gain a foothold in the healthcare sector. The paper discusses the potential of multiple watermarking to address a number of health information management issues, such as protection of sensitive data, origin and data authentication, image archiving and retrieval. A wavelet-based multiple watermarking scheme focusing on these medical-oriented applications is presented; the scheme allows the physician to define a Region of Interest, whose diagnostic value is explicitly protected throughout the embedding process, since the only additional information inserted therein is for the purpose of integrity control. The rest part of the image casts multiple watermarks conveying the physician's digital signature, patient's sensitive data, and keywords allowing image retrieval. In order to increase data robustness, a form of hybrid coding is applied, which includes repetitive embedding of BCH encoded watermarks.