Optical imaging for diagnosis of rheumatoid arthritis automatic versus human evaluation.

Successful detection of rheumatoid arthritis (RA) at the early stages of development can significantly enhance the chances of effective therapy. The early onset of RA is often marked with inflammation of the synovial lining of the joint, a condition known as synovitis. Effective imaging of synovitis is therefore of critical importance. While dynamic, contrast-enhanced magnetic resonance imaging (MRI) is capable of effective imaging of synovitis, it is a costly modality. As an alternative, inexpensive approach, optical imaging post injection of the near-infrared fluorescent dye indocynine green (ICG) has been recently proposed for imaging RA. Evaluation of the obtained optical images is performed via examination by trained human readers. However, optical imaging has yet to achieve the diagnostic accuracy of MRI. In this paper we present a method for automatic evaluation of the fluorescence images and compare its performance with the human-based evaluation. Our method relies on our previous work on spatiotemporal analysis of image sequence with principal component analysis (PCA) to seek synovitis signal components with the help of a segmentation method. The results for a group of 600 joints, obtained from 20 patients, suggest improved diagnostic performance using the automatic approach in comparison to human-based evaluation

Comparison between a new reconstruction algorithm (OPED) and filtered backprojection (FBP) for MDCT data.

Previously the Orthogonal Polynomial Expansion on the Disk (OPED) algorithm was presented. Further, in prototype experiments in combination with the CT D`or geometry feasibility was demonstrated. In this study we implemented OPED with a clinical Scanner, and evaluated the potential using phantom studies. All studies were acquired on a Siemens Somatom 64 (Erlangen, Germany) scanner, where raw projection data were reconstructed with the conventional FBP reconstruction and the OPED algorithm. OPED allows one to use fan beam geometry directly without any additional procedures such as interpolation or rebinning if using the CT D`or geometry. In particular, OPED describes an approximation of the image function as a sum of polynomials using Chebychev polynomials. For performance evaluation, the Catphan phantom 600 was imaged. OPED Images where reconstructed using C++ and MATLAB® .We measured uniformity, MTF and CNR for different dose levels and compared these to standard FBP images reconstructions with different filter kernels. The integration and interpretation of the MDCT projection data for the OPED algorithm was accomplished. Reconstruction time is about 6 s on Quad-Core 3 GHz Intel Xeon processor. Typical artifacts are reduced when applying OPED. Using OPED the MTF maintains constant over the whole FOV. Uniformity and CNR are equal compared to FBP. Advantages of OPED were demonstrated by applying the algorithm to projections images from a clinical MDCT scanner. In the future, we see OPED applications for low-dose or limited angle geometries to reduce the radiation dose while improving diagnostic quality of the reconstructed slices

Spatiotemporal analysis for indocyanine green-aided imaging of rheumatoid arthritis in hand joints.

ABSTRACT. Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease, with a prevalence of 0.5 to 1% in the general population. Imaging can possibly aid in early diagnosis, crucial to effective personalized therapeutic strategies and treatment follow-up. The intravenous administration of indocyanine green (ICG) has been considered for identifying synovial hyperperfusion as an RA physiological biomarker. However, while the distribution of ICG in the human hand is a time-dependent process, the particular biodistribution dynamic patterns established following intravenous administration have not yet been studied. For this reason, the dynamic relationships of ICG distribution in the human hand in RA patients using a method based on principal component analysis are analyzed. In vivo analyses were corroborated by simulations of clinical scenarios using a finite element method. Observations of spatiotemporal characteristics are contrasted to fluorescence intensity images and magnetic resonance images of the hand joints, employed as the anatomical and diagnostic reference. Processing results for 450 joints from 5 healthy volunteers and 10 patients show that image features obtained from the spatiotemporal analysis offer good congruence with synovitis and reveal better detection performance compared to observations of raw fluorescence intensity images

Magnetic resonance imaging of less common pancreatic malignancies and pancreatic tumors with malignant potential

Pancreatic tumors are an increasingly common finding in abdominal imaging. Various kinds of pathologies of the pancreas are well known, but it often remains difficult to classify the lesions radiologically in respect of type and grade of malignancy. Magnetic resonance imaging (MRI) is the method of choice for the evaluation of pancreatic pathologies due to its superior soft tissue contrast. In this article we present a selection of less common malignant and potentially malignant pancreatic neoplasms with their characteristic appearance on established MRI sequences with and without contrast enhancement

Whole-body MRI in children with langerhans cell histiocytosis for the evaluation of the skeletal system.

The usefulness of whole-body MRI (WB-MRI) for the detection of skeletal lesions in patients with Langerhans cell histiocytosis should be documented on the basis of case presentations. MATERIALS AND METHODS: In six patients with histologically proven Langerhans cell histiocytosis, 14 WB-MRI examinations were performed to evaluate the skeletal system within disease staging (6 primary, 8 follow-up examinations). The examinations were performed on a 1.5 Tesla, 32-channel whole-body scanner. The examination protocol consisted of T 1-weighted and STIR sequences in coronal and sagittal orientation. For comparison, radiographs of the initial skeletal lesions and those that were additionally detected on WB-MRI were available. RESULTS: In 4 patients no additional skeletal lesions were found on WB-MRI besides the initial lesion leading to the diagnosis of unifocal single system disease. In 2 patients WB-MRI was able to identify additional skeletal lesions. In a 5 S year-old boy with the primary lesion located in the cervical spine, a second lesion was detected in the lumbar spine on the initial scan and in the skull and proximal femur during follow-up examination. In a 12 year-old girl with a primary lesion of the thoracic spine, WB-MRI diagnosed additional lesions in the pelvic bone and the tibia. In both patients the diagnosis of multifocal skeletal involvement led to chemotherapy. During follow-up examination, the healing response under therapy could be demonstrated. Comparison with conventional imaging showed that especially lesions located in the spine or the pelvis were not detectable on radiographs even when knowing the MR results. CONCLUSION: The extent of skeletal involvement in Langerhans cell histiocytosis has crucial impact on therapy and prognosis. Whole-body MRI has been reported to be an established method for the evaluation of disseminated skeletal disease with distinct advantages over conventional radiography and bone scintigraphy. Our results suggest that WB-MRI should also be the imaging modality of choice for the assessment of skeletal involvement in children with Langerhans cell histiocytosis

Fluorescence-aided tomographic imaging of synovitis in the human finger.

Purpose To propose and evaluate indocyanine green (ICG)-enhanced tomographic optical imaging for detection and characterization of synovitis in affected finger joints of patients with rheumatoid arthritis and differentiation from healthy joints in comparison to 3-T magnetic resonance (MR) imaging. Materials and Methods This prospective pilot study was approved by the institutional ethics committee. Six arthritic proximal interphalangeal (PIP) joints in six patients (five women and one man; mean age ± standard deviation, 62.6 years ± 13.3) with clinically determined rheumatoid arthritis and six healthy PIP joints from six volunteers (four women and two men; mean age, 41.5 years ± 20.2) were examined with an ICG-enhanced fluorescence molecular tomography (FMT) system and 3-T MR imaging as the standard of reference. The degree of inflammation was graded semiquantitatively on a four-point ordinate scale according to the Outcome Measures in Rheumatology Clinical Trials Rheumatoid Arthritis MR Imaging Score, or OMERACT RAMRIS. FMT reconstructions were coregistered with the MR images. Groups were compared by using a two-sided t test, and a weighted κ coefficient was used for comparing FMT and MR imaging semiquantitative scores, as well as assessing intrareader agreement. Results FMT was used to detect synovitis in all arthritic joints. The reconstructed FMT signal correlated with MR imaging findings in intensity and spatial, transverse profile. Semiquantitative scoring of FMT correlated well with MR imaging findings (weighted κ coefficient = 0.90). The reconstructed quantitative FMT signal, denoting synovial hyperperfusion, was used to differentiate between synovitis and healthy joints (healthy joints, 1.25 ± 0.59; arthritic joints, 3.13 ± 1.03; P < .001). Conclusion FMT enhanced with ICG provided depth-resolved imaging of synovitis in PIP joints. FMT may help detect synovitis in patients with rheumatoid arthritis

Cascaded systems analysis in conventional X-ray CT: A new, objective approach.

The objective of this study is to separately analyse the effects of detection and image reconstruction on computed tomography (CT) performance to characterise standard and new CT systems. The focus here was on the determination of quantifiable parameters, such as the modulation transfer function, noise power spectrum and quantum efficiency of the detector and the entire system, considering the CT image and the raw data set. Because of the conversion of raw data and image data to the absolute scale of the photon number, a quantitative comparison between the quality parameters of both data sets is possible in this approach. The effort of the proposed method using simple, standardised test phantoms is comparable with the effort in the quality control in classical projection radiography. For the first time, the quantum efficiency of a CT detector and the entire system that is used in the daily clinical practice could be determined. This system reached a quantum efficiency up to 12 %

Evaluation of phase-sensitive versus magnitude reconstructed inversion recovery imaging for the assessment of myocardial infarction in mice with a clinical magnetic resonance scanner.

PURPOSE: To evaluate phase-sensitive inversion-recovery (PSIR) imaging at 1.5 T in a mouse model of permanent coronary artery ligation as a potentially rapid and robust alternative for the accurate assessment of myocardial infarction (MI) by cardiac magnetic resonance imaging (MRI). MATERIALS AND METHODS: PSIR late gadolinium enhancement (LGE) imaging was compared to conventional 2D segmented inversion-recovery imaging for the assessment of murine MI. RESULTS: PSIR images provided comparable contrast and kinetics of intravenously injected gadopentetate dimeglumine (Gd-DTPA). At the mid-ventricular level there was good agreement between conventional IR and PSIR for infarct size assessment. After intravenous injection a limited time window of ∼6 minutes is available for delayed enhancement imaging in mice. Whole-heart infarct imaging with 1 mm thick slices was only possible in this restricted time frame when the PSIR method is applied, avoiding the need for repetitively adapting the correct inversion time. Infarct size determined by PSIR MRI demonstrated good agreement with postmortem histology. Infarct size determined by PSIR LGE MRI inversely correlates with left-ventricular function on day 7 after MI. CONCLUSION: The PSIR technique provides stable and consistent contrast between hyperenhanced and remote myocardium independent of the selected inversion time (TI) and proved to be a robust, fast, and accurate tool for the assessment of MI in mice