Voxel-based mapping of five MR biomarkers in the wrist bone marrow.

OBJECTIVE: MRI is a reliable and accurate technique to characterize rheumatoid arthritis. The aim of this study was to provide voxel-by-voxel 3D maps of the proton density fat fraction (PDFF), the T1 of water (T1W), the T1 of fat (T1F), the T2* of water (T2*W), the T2* of fat (T2*F) in the wrist bone marrow. MATERIALS AND METHODS: The experiments were conducted on 14 healthy volunteers (mean age: 24 ± 4). The data were acquired at 1.5 T using two optimized four-echo 3D 1.2 × 1.2 × 1.2 mm3-isotropic spoiled gradient sequences. A repeatability study was carried out. The measurements were done using a homemade parametric viewer software. RESULTS: The inter-volunteer results were, on average: PDFF = 86 ± 3%, T1W = 441 ± 113 ms, T1F = 245 ± 19 ms, T2*W = 6 ± 1 ms and T2*F = 16 ± 3 ms. The coefficients of variation were for fat based biomarkers CVPDFF < 5%, CVT1F < 15% and CVT2*F < 10% in the repeatability study. DISCUSSION: The protocol and quantification tool proposed in this study provide high-resolution voxel-by-voxel 3D maps of five biomarkers in the wrist in less than 4 min of acquisition.

Measurements of Diffusion and Perfusion in Vertebral Bone Marrow Using Intravoxel Incoherent Motion (IVIM) With Multishot, Readout-Segmented (RESOLVE) Echo-Planar Imaging.

BACKGROUND: A limited number of studies have used the intravoxel incoherent motion (IVIM) approach on bone marrow. In none of the previous studies were the effects of fat suppression on the IVIM parameters investigated. PURPOSE: To measure the water diffusion coefficient and the perfusion fraction in vertebral bone marrow using IVIM with multishot, readout-segmented (RESOLVE) echo-planar imaging and to assess the effects of different fat suppression techniques on the measurement of the IVIM parameters. STUDY TYPE: Prospective. POPULATION/SUBJECTS: Six healthy volunteers (24.2 ± 4.3 years). FIELD STRENGTH/SEQUENCE: 1.5T, RESOLVE. ASSESSMENT: Four experiments were performed: 1) RESOLVE imaging without fat suppression, 2) with fat saturation (FS), 3) with spectral attenuated inversion recovery (SPAIR), and 4) with short-tau inversion recovery (STIR). The water diffusion coefficient D, pseudo-diffusion coefficient D*, and the perfusion fraction f were assessed in the vertebral bodies of the lumbar vertebrae. STATISTICAL TESTS: One-way repeated-measures analysis of variance (ANOVA) followed by Bonferroni's multiple comparison test. RESULTS: The RESOLVE IVIM protocol allowed for measurement of D, D*, and f in all volunteers. The signal of lipid protons affected the quantification of the IVIM diffusion coefficient: D = 0.24 ± 0.10 (×10-3 mm2 /s), no FS; D = 0.43 ± 0.07 (×10-3 mm2 /s), FS; D = 0.42 ± 0.07 (×10-3 mm2 /s), SPAIR; D = 0.35 ± 0.10 (×10-3 mm2 /s), STIR; and IVIM perfusion fraction f = 7.5 ± 1.9% no FS, f = 14.5 ± 5.4%, FS; f = 12.5 ± 2.6%, SPAIR; f = 18.1 ± 6.1%, STIR. No significant effect (P = 0.36) was found on the quantification of D*. DATA CONCLUSION: An IVIM-MRI protocol using the RESOLVE sequence was implemented for measurements of vertebral bone marrow diffusion and the perfusion. The comparison between the protocols with and without fat suppression indicates that the lipid signal results in an underestimation of both D and f. LEVEL OF EVIDENCE: Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;49:768-776.

Breath-hold MR measurements of fat fraction, T1 , and T2 * of water and fat in vertebral bone marrow.

PURPOSE: To assess the feasibility of measuring the fat fraction, T1 and T2 * relaxation times of water and fat signals in vertebral bone marrow using breath-hold magnetic resonance imaging (MRI) gradient echo images of the spine. MATERIALS AND METHODS: MRI experiments were performed at 1.5T on eight healthy volunteers (35.1 ± 15.7 years, five men and three women) using two sagittal four-echo 3D gradient echo volumetric interpolated breath-hold examination (VIBE Dixon) sequences acquired at two different flip angles (5° and 15°). The water/fat decomposition was performed in the vertebral bodies of L1 to L5 by fitting the signal to a function that depends on the echo time and the flip angle to calculate the fat fraction (FF) and T1 and T2 * relaxation times of water and fat signals. Repeatability was assessed by scanning one volunteer six times. RESULTS: The mean fat fraction over L1 to L5 was 33 ± 8%. The mean T1 and T2 * of water and fat signals were respectively T1w = 701 ± 151 msec, T2 *w = 13.7 ± 2.9 msec, T1f = 334 ± 113 msec, and T2 *f = 11.4 ± 2.7 msec. When considering each vertebra separately, the fat fraction increased from L1 to L5 and the T1w decreased from L1 to L5. The mean coefficients of variation obtained from the repeatability study were 8% (FF), 11% (T1w ), 17% (T1f ), 8% (T2 *w ), and 27% (T2 *f ). CONCLUSION: The method introduced in the current study allows for the measurement of the fat fraction and water and fat relaxation times, with a total acquisition time of less than 40 seconds. J. Magn. Reson. Imaging 2016;44:549-555.

MRI image artifact ontology: a proposed method for improved recognition.

UNLABELLED: Magnetic Resonance Imaging is an essential diagnostic imaging technique. The complexity of interpreting MRI images is often compounded by the presence of a wide range of artifacts which are often challenging to identify and eliminate. Ontology permits the construction of a knowledge database with which users can interact given an appropriate interface. The goal of this work is to create an interactive tool for the ontology of MRI artifacts that will allow a radiologist to compare any given MRI artifact image with those contained in the ontology. MATERIAL AND METHOD: Using Protégé 4, we have constructed the ontology with input from an expert in MRI artifacts and utilizing images exemplifying such artifacts. The graphical user interface has been built in Java and the linkage with the ontology made with Owl API. RESULTS: Using the tool, users can compare imaging artifacts encountered in daily practice to those in the database. Once a user has identified the image the most similar to their own, they then have instantaneous access to the knowledge contained in the ontology about the artifact. Individual users can also submit images and have access to DICOM data.

Ontology driven decision support systems for medical diagnosis - an interactive form for consultation in patients with plasma cell disease.

Multiple myeloma (MM) is a malignant disorder characterized by the monoclonal proliferation of B cell derived plasma cells in the bone marrow. The diagnosis depends on the identification of abnormal monoclonal marrow plasma cells, monoclonal protein in the serum or urine, evidence of end-organ damage, and a clinical picture consistent with MM. The distinction between MM stages- monoclonal gammopathy of undetermined significance or indolent myeloma-is critical in guiding therapy. This paper describes how to produce ontology-driven semiological rules base (SRB) and a consultation form to aid in the diagnosis of plasma cells diseases. We have extracted the MM sub-ontology from the NCI Thesaurus. Using Protégé 3.4.2 and owl1, criteria in the literature for the diagnosis and staging of MM have been added to the ontology. All quantitative parameters have been transformed to a qualitative format. A formal description of MM variants and stages has been given. The obtained ontology has been checked by a reasoner and instantiated to obtain a SRB. The form created has been tested and evaluated utilizing 63 clinical medical reports. The likelihood for a disease being the correct diagnosis is determined by computing a ratio. The resulting tool is relevant for MM diagnosis and staging.

Texture analysis software: integration with a radiological workstation.

Image analysis is the daily task of radiologists. The texture of a structure or imaging finding can be more difficult to describe than other parameters. Image processing can help the radiologist in completing this difficult task. The aim of this article is to explain how we have developed texture analysis software and integrated it into a standard radiological workstation. The texture analysis method has been divided into three steps: definition of primitive elements, counting, and statistical analysis. The software was developed in C++ and integrated into a Siemens workstation with a graphical user interface. The results of analyses may be exported in Excel format. The software allows users to perform texture analyses on any type of radiological image without the need for image transfer by simply placing a region of interest. This tool has already been used to assess the trabecular network of vertebra. The integration of such software into PACS extends the applicability of texture analysis beyond that of a mere research tool and facilitates its use in routine clinical practice.

Creating an ontology driven rules base for an expert system for medical diagnosis.

Expert systems of the 1980s have failed on the difficulties of maintaining large rule bases. The current work proposes a method to achieve and maintain rule bases grounded on ontologies (like NCIT). The process described here for an expert system on plasma cell disorder encompasses extraction of a sub-ontology and automatic and comprehensive generation of production rules. The creation of rules is not based directly on classes, but on individuals (instances). Instances can be considered as prototypes of diseases formally defined by "destrictions" in the ontology. Thus, it is possible to use this process to make diagnoses of diseases. The perspectives of this work are considered: the process described with an ontology formalized in OWL1 can be extended by using an ontology in OWL2 and allow reasoning about numerical data in addition to symbolic data.

Creating a magnetic resonance imaging ontology.

The goal of this work is to build an ontology of Magnetic Resonance Imaging. The MRI domain has been analysed regarding MRI simulators and the DICOM standard. Tow MRI simulators have been analysed: JEMRIS, which is developed in XML and C++, has a hierarchical organisation and SIMRI, which is developed in C, has a good representation of MRI physical processes. To build the ontology we have used Protégé 4, owl2 that allows quantitative representations. The ontology has been validated by a reasoner (Fact++) and by a good representation of DICOM headers and of MRI processes. The MRI ontology would improved MRI simulators and eased semantic interoperability.

Confounding factors in multi-parametric q-MRI protocol: A study of bone marrow biomarkers at 1.5 T.

OBJECT: The MRI tissue characterization of vertebral bone marrow includes the measurement of proton density fat fraction (PDFF), T1 and T2* relaxation times of the water and fat components (T1W, T1F, T2*W, T2*F), IVIM diffusion D, perfusion fraction f and pseudo-diffusion coefficient D*. However, the measurement of these vertebral bone marrow biomarkers (VBMBs) is affected with several confounding factors. In the current study, we investigated these confounding factors including the regional variation taking the example of variation between the anterior and posterior area in lumbar vertebrae, B1 inhomogeneity and the effect of fat suppression on f. MATERIALS AND METHODS: A fat suppressed diffusion-weighted sequence and two 3D gradient multi-echo sequences were used for the measurements of the seven VBMBs. A turbo flash B1 map sequence was used to estimate B1 inhomogeneities and thus, to correct flip angle for T1 quantification. We introduced a correction to perfusion fraction f measured with fat suppression, namely fPDFF. RESULTS: A significant difference in the values of PDFF, f and fPDFF, T1F, T2*W and D was observed between the anterior and posterior region. Although, little variations of flip angle were observed in this anterior-posterior direction in one vertebra but larger variations were observed in head-feet direction from L1 to L5 vertebrae. DISCUSSION: The regional difference in PDFF, fPDFF and T2*W can be ascribed to differences in the trabecular bone density and vascular network within vertebrae. The regional variation of VBMBs shows that care should be taken in reproducing the same region-of-interest location along a longitudinal study. The same attention should be taken while measuring f in fatty environment, and measuring T1. Furthermore, the MRI-protocol presented here allows for measurements of seven VBMBs in less than 6 min and is of interest for longitudinal studies of bone marrow diseases.

Using an Elastic Band Device After a Severe Obstetric Pubic Symphyseal Separation: Clinical and Imaging Evaluation.

BACKGROUND: Severe separation of the pubic symphysis is a rare delivery complication. Facing this pathology, we decided to study a new elastic band device. METHOD: To evaluate the elastic band device, clinical (pain-rated) and imaging (magnetic resonance imaging and radiography) evaluations with and without the device were performed. The elastic band device is a European Conformity-certified medical device, which is made of neoprene straps, that reduces the mobility of the pelvis and the use of the internal rotator muscles. EXPERIENCE: Once the elastic band device was in place, on postpartum day 1, radiography showed a decrease of the pubic width from 41 to 12 mm. Furthermore, pain decreased from 10 of 10 to 2 of 10 in 2 days, allowing the patient to ambulate and avoid surgery. After 1 month, the pubic width (6 mm) and anatomy were recovered but minor pain was still present with hip rotatory movements. The elastic band device was worn 24 hours a day from postpartum days 1-90 and 12 hours a day from postpartum days 90 to 150; afterward, the patient returned to normal life without the elastic band device. CONCLUSION: Use of an elastic band device was associated with a reduction of the pubic width and pain associated after obstetric pubic symphysis separation.

A fast method for the quantification of fat fraction and relaxation times: Comparison of five sites of bone marrow.

PURPOSE: Bone marrow is found either as red bone marrow, which mainly contains haematopoietic cells, or yellow bone marrow, which mainly contains adipocytes. In adults, red bone marrow is principally located in the axial skeleton. A recent study has introduced a method to simultaneously estimate the fat fraction (FF), the T1 and T2* relaxation times of water (T1w, T2*w) and fat (T1f and T2*f) in the vertebral bone marrow. The aim of the current study was to measure FF, T1w, T1f, T2*w and T2*f in five sites of bone marrow, and to assess the presence of regional variations. METHODS: MRI experiments were performed at 1.5T on five healthy volunteers (31.6±15.6years) using a prototype chemical-shift-encoded 3D multi-gradient-echo sequence (VIBE) acquired with two flip angles. Acquisitions were performed in the shoulders, lumbar spine and pelvis, with acquisition times of <25seconds per sequence. Signal intensities of magnitude images of the individual echoes were used to fit the signal and compute FF, T1w, T1f, T2*w and T2*f in the humerus, sternum, vertebra, ilium and femur. RESULTS: Regional variations of fat fraction and relaxation times were observed in these sites, with higher fat fraction and longer T1w in the epiphyses of long bones. A high correlation between FF and T1w was measured in these bones (R=0.84 in the humerus and R=0.84 in the femur). In most sites, there was a significant difference between water and fat relaxation times, attesting the relevance of measuring these parameters separately. CONCLUSION: The method proposed in the current study allowed for measurements of FF, T1w, T1f, T2*w and T2*f in five sites of bone marrow. Regional variations of these parameters were observed and a strong negative correlation between the T1 of water and the fat fraction in bones with high fat fractions was found.

A unified representation of findings in clinical radiology using the UMLS and DICOM.

PURPOSE: Collecting and analyzing findings constitute the basis of medical activity. Computer assisted medical activity raises the problem of modelling findings. We propose a unified representation of findings integrating the representations of findings in the GAMUTS in Radiology [M.M. Reeder, B. Felson, GAMUTS in radiology Comprehensive lists of roentgen differential diagnosis, fourth ed., 2003], the Unified Medical Language System (UMLS), and the Digital Imaging and Communication in Medicine Structured Report (DICOM-SR). MATERIALS AND METHODS: Starting from a corpus of findings in bone and joint radiology [M.M. Reeder, B. Felson, GAMUTS in Radiology comprehensive lists of roentgen differential diagnosis, fourth ed., 2003] (3481 words), an automated mapping to the UMLS was performed with the Metamap Program. The resulting UMLS terms and Semantic Types were analyzed in order to find a generic template in accordance with DICOM-SR structure. RESULTS: UMLS Concepts were missing for 45% of the GAMUTS findings. Three kinds of regularities were observed in the way the Semantic Types were combined: "pathological findings", "physiological findings" and "anatomical findings". A generic and original DICOM-SR template modelling finding was proposed. It was evaluated for representing GAMUTS jaws findings. 21% missing terms had to be picked up from Radlex (5%) or created (16%). DISCUSSION-CONCLUSION: This article shows that it is possible to represent findings using the UMLS and the DICOM SR formalism with a semi-automated method. The Metamap program helped to find a model to represent the semantic structure of free texts with standardized terms (UMLS Concepts). Nevertheless, the coverage of the UMLS is not comprehensive. This study shows that the UMLS should include more technical concepts and more concepts regarding findings, signs and symptoms to be suitable for radiology representation. The semi-automated translation of the whole GAMUTS using the UMLS concepts and the DICOM SR relations could help to create or supplement the DCMR Templates and Context Groups pertaining to the description of imaging findings.

Toward a unified representation of findings in clinical radiology.

The representations of findings in clinical radiology are heterogeneous. Motivations for developing a unified representation include the semantic integration of medical reports based on DICOM-SR(Digital Image Communication in Medicine Structured Reporting), bibliographic databases in the context of evidence-based medicine, and teaching resources. In this work, we propose a unified representation integrating the representations of findings in the UMLS, the GAMUTS in Radiology and the DICOM-SR. We analyse the UMLS and the DCMR (DICOM Content Mapping Resource) of DICOM SR to figure out their own representation of findings. Then we set up a syntax between the UMLS concepts using DICOM-SR relations in order to rewrite the GAMUTS sentences. The translation of the whole GAMUTS using the UMLS concepts and the DICOM SR syntax could be a method to create or supplement the DCMR TIDs (Template ID : Identifier of a Template) and CIDs (Context ID : Identifier of a Context Group) in the field of description of findings in medical imaging. This method could also enable to give an ontologic dimension to the DICOM SR representation system of information. The meaning of the CIDs would then be enhanced far beyond the simple use of the SNOMED vocabulary.