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Biomedical subjects

Osman Ratib

Publications and source records attributed to Osman Ratib.

At least 19 recordsLinked to original sources
PubMed2006

(11)C-acetate PET in the early evaluation of prostate cancer recurrence.

PURPOSE: The first aim of the study was to investigate the diagnostic potential of (11)C-acetate PET in the early detection of prostate cancer recurrence. A second aim was the evaluation of early and late PET in this context. METHODS: The study population comprised 32 prostate cancer patients with early evidence of relapse after initial radiotherapy (group A) or radical surgery (group B). The median PSA of group A (n=17) patients was 6 ng/ml (range 2.6-30.2) while that of group B (n=15) was 0.4 ng/ml (range 0.08-4.8). Pelvic-abdominal-thoracic PET was started 2 min after injection of (11)C-acetate and evaluated after fusion with CT. RESULTS: Group A: Taking a SUV(max)> or =2 as the cut-off, PET showed local recurrences in 14/17 patients and two equivocal results. Distant disease was observed in six patients and an equivocal result was obtained in one. Endorectal MRI was positive in 12/12 patients. Biopsy confirmed local recurrence in six of six (100%) patients. PET was positive in five of the six patients with biopsy-proven recurrences, the result in the remaining patient being equivocal. Group B: Among the 15 patients, visual interpretation was positive for local recurrences in five patients and equivocal in four. One obturator lymph node was positive. Endorectal MRI was positive in 11/15 patients and equivocal in two. Positional correlation of positive/equivocal results on PET and endorectal MRI was observed in seven of nine patients. PSA decreased significantly after salvage radiotherapy in 8/14 patients, providing strong evidence for local recurrence. PET of the eight patients responding to RT was positive in three and equivocal in two. CONCLUSION: (11)C-acetate PET was found to be valuable in the early evaluation of prostate cancer relapse. Optimising scanning time and use of modern PET-CT equipment might allow further improvement.

Acetates↗
PubMed2006

Ventricular mechanical dyssynchrony and resynchronization therapy in heart failure: a new indication for Fourier analysis of gated blood-pool radionuclide ventriculography.

In patients with decreased left ventricular ejection fraction and conduction disease, ventricular mechanical dyssynchrony has been demonstrated. To date, resynchronization by biventricular pacing is increasingly used since it improves ventricular function and exercise capacity in patients with heart failure. To optimize and evaluate the effect of resynchronization therapy and to identify patients who may benefit from biventricular pacing the assessment of left ventricular synchronicity is essential. Therefore, a non-invasive and reproducible technique to obtain information on ventricular synchrony is clinically valuable. In this review, the technical background and the role of phase analysis of gated blood-pool nuclear ventriculography in the assessment of ventricular mechanical synchrony, especially in heart failure patients subjected to biventricular pacing, will be discussed.

Cardiac Pacing, Artificial↗
PubMed2006

Cardiac MR imaging: state of the technology.

Recent developments in magnetic resonance (MR) imaging of the heart have refocused attention on the potential of MR and continue to attract intense interest within the radiology and cardiology communities. Improvements in speed, image quality, reliability, and range of applications have evolved to the point where cardiac MR imaging is increasingly seen as a practical clinical tool. As is often the case with MR imaging, not all of the most powerful techniques are necessarily easy to master or understand, and many-nonspecialists and specialists alike-are challenged to stay abreast. This review covers some of the major milestones that have led to the current state of cardiac MR and attempts to put into context some concepts that, although technical, have a real impact on the diagnostic power of cardiac MR imaging. Topics discussed include functional imaging, myocardial viability and perfusion imaging, flow quantification, and coronary artery imaging. A review such as this can only scratch the surface of what is a dynamic interdisciplinary field, but the hope is that sufficient information and insight are provided to stimulate the motivated reader to take his or her interest to the next level.

Contrast Media↗
PubMed2005

General consumer communication tools for improved image management and communication in medicine.

We elected to explore new technologies emerging on the general consumer market that can improve and facilitate image and data communication in medical and clinical environment. These new technologies developed for communication and storage of data can improve the user convenience and facilitate the communication and transport of images and related data beyond the usual limits and restrictions of a traditional picture archiving and communication systems (PACS) network. We specifically tested and implemented three new technologies provided on Apple computer platforms. (1) We adopted the iPod, a MP3 portable player with a hard disk storage, to easily and quickly move large number of DICOM images. (2) We adopted iChat, a videoconference and instant-messaging software, to transmit DICOM images in real time to a distant computer for conferencing teleradiology. (3) Finally, we developed a direct secure interface to use the iDisk service, a file-sharing service based on the WebDAV technology, to send and share DICOM files between distant computers. These three technologies were integrated in a new open-source image navigation and display software called OsiriX allowing for manipulation and communication of multimodality and multidimensional DICOM image data sets. This software is freely available as an open-source project at http://homepage.mac.com/rossetantoine/OsiriX. Our experience showed that the implementation of these technologies allowed us to significantly enhance the existing PACS with valuable new features without any additional investment or the need for complex extensions of our infrastructure. The added features such as teleradiology, secure and convenient image and data communication, and the use of external data storage services open the gate to a much broader extension of our imaging infrastructure to the outside world.

Communication↗
PubMed2005

Impedance monitoring during catheter ablation of atrial fibrillation.

BACKGROUND: Delivery of radiofrequency energy in proximity of a pulmonary vein can cause vein stenosis. A sudden decrease in impedance as the catheter is moved from the vein into the left atrium (LA) has been used to define the pulmonary vein-LA transition during ablation procedures. OBJECTIVES: The purpose of this study was to define the variables affecting impedance measurement. METHODS: In vitro analysis of impedance was performed in a saline bath using sheaths and a plastic stereolithographic model of the LA. Impedance was continuously monitored during a calibrated pullback from the pulmonary vein into the LA in 37 veins of 10 patients referred for catheter ablation. Location of the catheter was confirmed by the following imaging modalities: intracardiac echocardiography, contrast venography, electroanatomic mapping, and computed tomography/magnetic resonance imaging (offline) in all patients. RESULTS: Larger cross-sectional areas containing the catheter correlated with lower impedance in an exponential manner both with respect to sheath size (R(2) = 0.99) and in the stereolithographic model (R(2) = 0.91). In vivo, the impedance in the pulmonary veins decreased in an exponential manner as the catheter was pulled back into the LA. However, impedance at the vein orifice was not significantly higher than the LA. A defined cutoff value for defining the pulmonary vein-LA transition could not be identified. CONCLUSION: The primary determinant of impedance is the cross-sectional area of the space containing the catheter. Impedance monitoring alone does not guarantee a catheter tip position outside the pulmonary vein. Intraprocedural imaging confirmation should be considered to avoid radiofrequency application within pulmonary veins.

Aged↗
PubMed2005

Comparison between 18F-FDG PET, in-line PET/CT, and software fusion for restaging of recurrent colorectal cancer.

UNLABELLED: The aim of this study was to compare PET with (18)F-FDG PET, in-line PET/CT, and software fusion of independently acquired CT and PET scans for staging of recurrent colorectal cancer (CRC). METHODS: Fifty-one patients with suspected recurrent CRC were studied with in-line PET/CT. Thirty-four of these patients underwent an additional CT scan of the chest or abdomen within 4 wk of PET/CT. Software fusion of PET and CT was performed using a fully automated, intensity-based algorithm. The accuracy of the coregistration of PET and CT scans was evaluated by measuring the distance between landmarks visible in the PET and CT images. Histologic evaluation and follow-up for 6 mo served as the gold standard for the presence or absence of recurrent CRC. RESULTS: On a patient basis, the accuracy of staging was significantly higher for in-line PET/CT than for PET (88% vs. 71%, P = 0.01). Software fusion of the independently acquired PET and CT images was unsuccessful in 8 patients (24%). In the remaining patients, the mean distance between 62 landmarks visible in PET and CT was 12.9 +/- 7.9 mm, whereas it was only 7.7 +/- 4.7 mm for in-line PET/CT (P < 0.001). CONCLUSION: In patients with suspected recurrent CRC, in-line PET/CT significantly improves staging compared with PET alone. Due to its high failure rate, software fusion of independently acquired PET and CT studies cannot be considered to represent an alternative to in-line PET/CT.

Algorithms↗
PubMed2005

Optimizing imaging protocols for overweight and obese patients: a lutetium orthosilicate PET/CT study.

UNLABELLED: High photon attenuation and scatter in obese patients affect image quality. The purpose of the current study was to optimize lutetium orthosilicate (LSO) PET image acquisition protocols in patients weighing > or =91 kg (200 lb). METHODS: Twenty-five consecutive patients (16 male and 9 female) weighing > or =91 kg (200 lb; range, 91-168 kg [200-370 lb]) were studied with LSO PET/CT. After intravenous injection of 7.77 MBq (0.21 mCi) of 18F-FDG per kilogram of body weight, PET emission scans were acquired for 7 min/bed position. Single-minute frames were extracted from the 7 min/bed position scans to reconstruct 1-7 min/bed position scans for each patient. Three reviewers independently analyzed all 7 reconstructed whole-body images of each patient. A consensus reading followed in cases of disagreement. Thus, 175 whole-body scans (7 per patient) were analyzed for number of hypermetabolic lesions. A region-of-interest approach was used to obtain a quantitative estimate of image quality. RESULTS: Fifty-nine hypermetabolic lesions identified on 7 min/bed position scans served as the reference standard. Interobserver concordance increased from 64% for 1 min/bed position scans to 70% for 3 min/bed position scans and 78% for 4 min/bed position scans. Concordance rates did not change for longer imaging durations. Region-of-interest analysis revealed that image noise decreased from 21% for 1 min/bed position scans to 14%, 13%, and 11% for, respectively, 4, 5, and 7 min/bed position scans. When compared with the reference standard, 14 lesions (24%) were missed on 1 min/bed position scans but only 2 (3%) on 4 min/bed position scans. Five minute/bed position scans were sufficient to detect all lesions identified on the 7 min/bed position scans. CONCLUSION: Lesion detectability and reader concordance peaked for 5 min/bed position scans, with no further diagnostic gain achieved by lengthening the duration of PET emission scanning. Thus, 5 min/bed position scans are sufficient for optimal lesion detection with LSO PET/CT in obese patients.

Female↗
PubMed2004

OsiriX: an open-source software for navigating in multidimensional DICOM images.

A multidimensional image navigation and display software was designed for display and interpretation of large sets of multidimensional and multimodality images such as combined PET-CT studies. The software is developed in Objective-C on a Macintosh platform under the MacOS X operating system using the GNUstep development environment. It also benefits from the extremely fast and optimized 3D graphic capabilities of the OpenGL graphic standard widely used for computer games optimized for taking advantage of any hardware graphic accelerator boards available. In the design of the software special attention was given to adapt the user interface to the specific and complex tasks of navigating through large sets of image data. An interactive jog-wheel device widely used in the video and movie industry was implemented to allow users to navigate in the different dimensions of an image set much faster than with a traditional mouse or on-screen cursors and sliders. The program can easily be adapted for very specific tasks that require a limited number of functions, by adding and removing tools from the program's toolbar and avoiding an overwhelming number of unnecessary tools and functions. The processing and image rendering tools of the software are based on the open-source libraries ITK and VTK. This ensures that all new developments in image processing that could emerge from other academic institutions using these libraries can be directly ported to the OsiriX program. OsiriX is provided free of charge under the GNU open-source licensing agreement at http://homepage.mac.com/rossetantoine/osirix.

Computer Graphics↗
PubMed2004

Casimage project: a digital teaching files authoring environment.

The goal of the Casimage project is to offer an authoring and editing environment integrated with the Picture Archiving and Communication Systems (PACS) for creating image-based electronic teaching files. This software is based on a client/server architecture allowing remote access of users to a central database. This authoring environment allows radiologists to create reference databases and collection of digital images for teaching and research directly from clinical cases being reviewed on PACS diagnostic workstations. The environment includes all tools to create teaching files, including textual description, annotations, and image manipulation. The software also allows users to generate stand-alone CD-ROMs and web-based teaching files to easily share their collections. The system includes a web server compatible with the Medical Imaging Resource Center standard (MIRC, http://mirc.rsna.org) to easily integrate collections in the RSNA web network dedicated to teaching files. This software could be installed on any PACS workstation to allow users to add new cases at any time and anywhere during clinical operations. Several images collections were created with this tool, including thoracic imaging that was subsequently made available on a CD-Rom and on our web site and through the MIRC network for public access.

CD-ROM↗
PubMed2004

PET/CT image navigation and communication.

UNLABELLED: The advent of multimodality imaging scanners combining PET and CT has led to a new paradigm in image display and presentation that raises new challenges in workstation interpretation software, image navigation, and communication. The essence of multimodality imaging is the ability to overlay imaging information from different modalities in a visually compelling fashion. This is accomplished by combining functional and anatomic data into multidimensional views using color-encoding techniques that provide visual clues on the spatial distribution of image data. DISCUSSION: Combined PET/CT scanners provide spatially registered images from the two modalities acquired simultaneously in a single imaging session. Special reconstruction software and image display programs are required to rescale the native images from different spatial resolution into orthogonal or oblique reformatted planes in which data from PET images are color coded and superimposed on corresponding anatomic CT images. The color overlay technique allows the user to visually identify areas of high tracer activity and determine the underlying anatomic structure. Because of the multidimensional nature of the data, visualization requires interactive multidimensional navigation techniques that allow the viewer to move the visualization planes through three spatial directions and two additional dimensions. The fourth dimension is the continuum blend from PET to CT fusion, and the fifth is the dynamic range of the CT images that can be adjusted to display different tissue characteristics, such as bones, soft tissue, and lungs. Software tools currently available are often relatively complex, requiring the user to perform cumbersome maneuvers and time-consuming image manipulation to navigate through all dimensions and obtain adequate image settings and plane positioning for diagnostic interpretation of the image data. Moreover, the ability to convey these images to referring physicians is usually limited because of the lack of adequate viewing software. Distribution of results is usually performed instead through static "snapshots" of the fused images generated by the interpreting radiologist. The ability of the referring physician to navigate through the set of multimodality image data is thus limited. CONCLUSION: The wider adoption of multimodality PET/CT imaging techniques in routine clinical use will depend heavily on the development of more adequate image display and navigation tools that allow interpreting physicians to navigate easily and efficiently through multiple dimensions of data. Distribution of results to referring physicians and care providers also requires new tools for interactively reviewing the multimodality data, and current static images obtained from fused image data remain inadequate for proper visualization of the true content of images.

Algorithms↗
PubMed2004

Cardiac pacemakers and central venous lines can induce focal artifacts on CT-corrected PET images.

UNLABELLED: PET/CT imaging can be associated with focal artifactual (18)F-FDG uptake introduced by metallic implants or contrast agents. It is unknown whether cardiac pacemakers or permanent central venous catheters can also result in such artifacts. METHODS: Twenty-seven patients with permanent central venous lines (13 men and 14 women; mean age +/- SD, 53.8 +/- 16.2 y) and 9 patients with pacemakers (7 men and 2 women; mean age +/- SD, 74.8 +/- 5.1 y) who were referred for a variety of oncologic indications were studied with lutetium-oxyorthosilicate-based dual-slice PET/CT after injection of 7.77 MBq/kg of (18)F-FDG. CT-corrected and -uncorrected PET images were reviewed, and (18)F-FDG uptake was graded as absent, mild, moderate, or intense. RESULTS: CT-corrected PET images revealed focally increased uptake of moderate intensity in all patients with cardiac pacemakers and focally increased uptake of mild intensity in 8 of 27 patients (29.6%) with central venous lines. CONCLUSION: Cardiac pacemakers and reservoirs of central venous lines can induce artifactual (18)F-FDG on CT-corrected PET images. Thus, in patients with permanent central lines or pacemakers, both corrected and uncorrected PET images need to be reviewed to avoid false-positive PET findings.

Aged↗
PubMed2004

Impact of patient weight and emission scan duration on PET/CT image quality and lesion detectability.

UNLABELLED: This study was performed to prospectively evaluate fast PET/CT imaging protocols using lutetium oxyorthosilicate (LSO) detector technology and 3-dimensional (3D) image-acquisition protocols. METHODS: Fifty-seven consecutive patients (30 male, 27 female; mean age, 58.6 +/- 15.7 y) were enrolled in the study. After intravenous injection of 7.77 MBq (0.21 mCi) of (18)F-FDG per kilogram, a standard whole-body CT study (80-110 s) and PET emission scan were acquired for 4 min/bed position in 49 patients and 3 min/bed position in 8 patients. One-minute-per-bed-position data were then extracted from the 3- or 4-min/bed position scans to reconstruct single-minute/bed position scans for each patient. Patients were subgrouped according to weight as follows: <59 kg (<130 lb; n = 15), 59-81 kg (130-179 lb; n = 33), and >or=82 kg (>or=180 lb; n = 9). Three experienced observers recorded numbers and locations of lesion by consensus and independently rated image quality as good, moderate, poor, or nondiagnostic. RESULTS: The observers analyzed 220 reconstructed whole-body PET images from 57 patients. They identified 114 lesions ranging in size from 0.7 to 7.0 cm on the 3- (n = 8) and 4-min/bed position images (n = 49). Of these, only 4 were missed on the 1-min/bed position scans, and all lesions were identified on the corresponding 2-min/bed position images. One- and 2-min/bed position image quality differed significantly from the 4-min/bed position image reference (P < 0.05). CONCLUSION: LSO PET detector technology permits fast 3D imaging protocols whereby weight-based emission scan durations ranging from 1 to 3 min/bed position provide similar lesion detectability when compared with 4-min/bed position images.

Body Weight↗
PubMed2003

From PACS to integrated EMR.

The integration of medical images as part of the patient record has always been a critical component of documentation and information supporting clinical decisions. In the past two decades the increased number of imaging procedures that allows a more accurate and more specific diagnosis has significantly increased and their role in patient management has grown rapidly. With the evolution toward digital modalities and management of medical images in a fully digital environment with the deployment of enterprise wide Picture Archiving Communication Systems (PACS) a wider and more rapid access to the images by referring physicians and clinicians has become possible. The parallel evolution of electronic medical records (EMR) supporting all other documents and clinical data in electronic format led to the necessity of integrating medial image data with the rest of the patient record. Although the marriage of medical images and patient record data in electronic format seems a very natural and necessary combination it has often been very slow in development due to the lack of standardization and clear understanding of clinical workflows and clinical requirements. Several early implementations demonstrated the added value of combining medical images with the patient record and have shown that the availability of data and images facilitates and improves the accuracy and efficiency of patient management. Recent efforts in industry and the academic community to harmonize and improve the integration of medical images with patient record, with the promotion of new standards and better definitions of clinical workflows and standard mechanism of integration of different types of data into unified data models, has facilitated the deployment of modern EMR. Also, a shift in paradigm due to recent technological revolutions such as the development of the World Wide Web and the concepts of portal servers for accessing data for multiple sources has significantly boosted the trends into open systems which allows easier and more functional integration of medical data from different sources. Furthermore, the emergence of a new strategy for software development, based on open source components, allows software programs to be shared and exchanged between different institutions leading to more rapid deployment of standardized electronic patient record.

Diffusion of Innovation↗
PubMedDate not supplied

Performance of 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography and integrated PET/CT in restaged breast cancer patients.

PURPOSE: This study was conducted to compare the clinical stage derived from 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) to that of integrated PET/computed tomography (CT) in restaged breast cancer patients. PROCEDURES: Fifty-eight female patients (age range 29-80 years, mean age +/-SD, 53.3 +/- 11.7 years) underwent PET/CT restaging for breast cancer. Two experienced nuclear medicine physicians interpreted PET images. A radiologist was added for reading PET/CT studies. A patient-based analysis was performed. Histopathological findings, correlative imaging studies, changes in number, size, and hypermetabolic activity of suspicious lesions and/or patient outcome served as standard of reference for determining the diagnostic accuracy of both modalities. RESULTS: PET staged 79.3% (46/58) of the patients correctly, overstaged seven (12.1%), and understaged five patients (8.6%). Integrated PET/CT staged 89.7% (52/58) of the patients correctly, overstaged four (6.9%), and understaged two patients (3.4%). The staging accuracy of PET/CT was not significantly better than that of PET alone (p = 0.059). Lesions exhibiting mild hypermetabolic activity, benign inflammatory lesions, and physiological variants largely explained incorrect PET findings. CONCLUSION: Integrated PET/CT only marginally improves the restaging accuracy over PET alone (p = 0.059) in breast cancer patients.

Adult↗
PubMedDate not supplied

Comparison between 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography and positron emission tomography/computed tomography hardware fusion for staging of patients with lymphoma.

PURPOSE: 2-Deoxy-2-[18F]fluoro-D-Glucose positron emission tomography (FDG-PET) stages patients with Hodgkin's disease (HD) and Non-Hodgkin's lymphoma (NHL) with higher accuracy than computed tomography (CT). We sought to determine whether integrated (hardware) fused PET/CT imaging results in further improvements in staging accuracy. PROCEDURES: Seventy-three patients (age 51 +/- 17 years, 37 female, 36 male) with HD (n = 20) or NHL (n = 53) undergoing staging were studied with an integrated PET/CT system. Image findings were verified by clinical follow up, additional imaging and when available, histology. RESULTS: Thirty-four of 73 patients (46.5%) had evidence of disease and 39 were disease free as confirmed by clinical evaluation and follow-up for 41 +/- 22 weeks (n = 73), including biopsy (n = 26), and other imaging modalities (n = 52) when available. A discordant image interpretation between PET and PET/CT occurred in seven patients (10%). PET/CT correctly upstaged two and downstaged five patients. Overall staging was accurate in 93% with PET/CT and 84% with PET (P = 0.03). CONCLUSION: Lymphoma is staged with higher accuracy using PET/CT than PET alone.

Female↗
PubMedDate not supplied

Integration of a multimedia teaching and reference database in a PACS environment.

In one radiology department, a computerized authoring and editing environment was developed and integrated with the picture archiving and communication systems (PACS) for creation of image-based electronic teaching files to replace a collection of printed film images. This multimedia database and authoring environment allows physicians to create reference databases for teaching and research directly from clinical cases being reviewed on PACS diagnostic workstations. The database engine allows users to generate stand-alone CD-ROMs (compact disks, read-only memory) and World Wide Web-based teaching files. The system is fully compliant with the Digital Imaging and Communications in Medicine (DICOM) standard and supports a large number of standard multimedia image file formats. The focus of the development was on convenience and ease of use of a generic system adaptable to all users. The software was integrated on the PACS workstations to allow users to add new cases to the database at any time and anywhere in the department. A pilot system was implemented in clinical operation, with a central server and several client units.

CD-ROM↗