Axial Mapping Research Articles

Axial shift mapping: a self-referencing test for measuring the axial figure of near-cylindrical surfaces

Lateral shearing self-referencing interferometry methods shift the surface under test between measurements to separate its topography from that of the reference surface. However, rigid body errors occur during shifting, creating an ambiguity in the quadratic term of the extracted surfaces. We present axial shift mapping, a lateral shearing self-referencing interferometry method for cylinders, in which the quadratic ambiguity is resolved by measuring the rigid body errors using known artifact mirrors residing in the interferometer’s field of view. First, one-dimensional lines of a flat mirror are measured with 2.8 nm RMS difference compared to a three flat test. Then, axial shift mapping is extended to cylindrical surfaces using a computer generated hologram. We find that axial shift mapping results in full surface extraction of cylindrical optics, along the axial direction, with a repeatability of 4.4 nm RMS. We also find that the reference surface extracted through axial shift mapping is within 4.5 nm RMS of the transmitted wavefront error of the computer generated hologram substrate, which was expected to be the largest contribution of reference wavefront error.

An MR-based radiomics nomogram including information from the peritumoral region to predict deep myometrial invasion in stage I endometrioid adenocarcinoma: a preliminary study.

To develop and validate an MR-based radiomics nomogram combining different imaging sequences (ADC mapping and T2 weighted imaging (T2WI)), different tumor regions (combined intra- and peritumoral regions), and different parameters (clinical features, tumor morphological features, and radiomics features) while considering different MR field strengths in predicting deep myometrial invasion (MI) in Stage I endometrioid adenocarcinoma (EEA). A total of 202 patients were retrospectively analyzed and divided into two cohorts (training cohort, 1.5 T MR, n = 131; validation cohort, 3.0 T MR, n = 71). Axial ADC mapping and T2WI were conducted. Radiomics features were extracted from intra- and peritumoral regions. Least absolute shrinkage and selection operator regression, univariate analysis, and multivariate logistic regression were used to select radiomics features and tumor morphological and clinical parameters. The area under the receiver operator characteristic curve (AUC) was calculated to evaluate the performance of the prediction model and radiomics nomogram. Ten radiomics features, 4 morphological parameters and 1 clinical characteristic were selected. The radiomics nomogram achieved good discrimination between the superficial and deep MI cohorts. The AUC was 0.927 (95% confidence interval [CI]: 0.865, 0.967) in the training cohort and 0.921 (95% CI: 0.872, 0.948) in the validation cohort. The specificity and sensitivity were 92.0 and 78.9% in the training cohort and 83.0 and 77.8% in the validation cohort, respectively. The radiomics nomogram showed good performance in predicting the depth of MI in Stage I EEA before surgery and might be useful for surgical patient management. An MR-based radiomics nomogram was useful for predicting deep MI in Stage I EEA patients (AUCtrain = 0.927, AUCvalidation = 0.921). The intra- and peritumoral radiomics features complemented each other. The nomogram was developed and validated with different MR field strengths, suggesting that the model demonstrates good generalizability.

Exploring the barriers and enablers of diabetes care in a remote Australian context: A qualitative study.

This qualitative study explored the current barriers and enablers of diabetes care in the Indian Ocean Territories (IOT). A constructivist grounded theory approach that incorporated semi-structured telephone interviews was employed. Initial analysis of the interview transcripts used a line-by-line approach, to identify recurring themes, connections, and patterns, before they were re-labelled and categorised. This was followed by axial coding, categorisation refinement, and mapping of diabetes triggers in the IOT. The IOT, consisting of Christmas Island and the Cocos (Keeling) Islands, are some of the most remote areas in Australia. When compared with mainland Australia, the prevalence of type 2 diabetes in the IOT is disproportionately higher. There were no known cases of type 1 diabetes at the time of the study. Like other remote communities, these communities experience difficulties in accessing health services to prevent and manage diabetes. Twenty health care professionals and health service administrators in the IOT took part in semi-structured telephone interviews held during April-June 2020. Participants included GPs, nurses, dietitians, social and community services workers, school principals, and administrators. The interview questions focused on their perceptions of the current diabetes care in place in the IOT and their views on the challenges of providing diabetes care in the IOT. We identified four main barriers and two main enabling factors to the provision of effective diabetes care in the IOT. The barriers were: (i) societal influences; (ii) family; (iii) changing availability of food; (v) sustainability and communication. The two main enablers were: (i) tailoring interventions to meet local and cultural needs and values; and (ii) proactive compliance with the medical model of care. Due to the cultural and linguistic diversity within the IOT, many of the identified barriers and enablers are unique to this community and need to be considered and incorporated into routine diabetes care to ensure successful and effective delivery of services in a remote context.

T2 Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation.

In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T2 mapping, a well-established method for cartilage lesions assessment. To examine short-term consequences of single first-time LPD in teenagers by T2 mapping of the patellar-cartilage state. Prospective. 95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22). 3.0 T; axial T2 mapping acquired using a 2D turbo spin-echo sequence. MRI examination was conducted 2-4 months after first LPD. T2 values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts. ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05. In lateral patellar cartilage, a significant increase in T2 values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T2 times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T2 values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T2 in the medial superficial layer (41.0 vs. 43.8 msec, 0.55). The study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage. 2 TECHNICAL EFFICACY STAGE: 2.

3D mapping of intra-articular calcaneal fractures

To determine the pattern of intra-articular calcaneal fractures (ICFs) by a three-dimensional (3D) mapping and determine whether there were consistent fracture patterns and comminution zones. In this study, 67 patients with ICFS by CT scan were included. The calcaneal fractures fragments in CT were multiplanar reconstructed and virtual reduced. 3D heat mapping was subsequently created by graphically superimposing all fracture lines onto a standard calcaneal template. The cohort included 26 (38.8%) left calcaneal fractures, 27 (40.30%) right calcaneal fractures, and 14 (20.9%) cases with bilateral fractures. Comminuted fractures accounted for 92.5%. Sagittal 3D mapping shows that the fracture line is mainly concentrated at the critical angle of Gissane and extending rear to the posterior of the tuberosity of the lateral wall and the anterior of the medial process of the calcaneus tuberosity but with more significant variation in the medial wall. The average angle of fracture lines concerning the long calcaneal axis (LCA) was 29.1° and 19.2° in the lateral and medial walls. Axial 3D mapping shows that fracture lines were primarily concentrated in the anterior area to the posterior joint facet and extending along the rear joint facet and calcaneus sulcus to the posteriorly of the tuberosity. The mean angle of fracture lines concerning the LAC was 11° in the axial wall. Our data provided elucidated that ICFs have consistent characteristic fracture patterns and comminution zones. This study provides visual guidelines for understanding fracture morphology, which may assist with fracture classification, preoperative planning, development of fixation concepts.

Metal-Induced Energy Transfer (MIET) for Live-Cell Imaging with Fluorescent Proteins

Metal-induced energy transfer (MIET) imaging is an easy-to-implement super-resolution modality that achieves nanometer resolution along the optical axis of a microscope. Although its capability in numerous biological and biophysical studies has been demonstrated, its implementation for live-cell imaging with fluorescent proteins is still lacking. Here, we present its applicability and capabilities for live-cell imaging with fluorescent proteins in diverse cell types (adult human stem cells, human osteo-sarcoma cells, and Dictyostelium discoideum cells), and with various fluorescent proteins (GFP, mScarlet, RFP, YPet). We show that MIET imaging achieves nanometer axial mapping of living cellular and subcellular components across multiple time scales, from a few milliseconds to hours, with negligible phototoxic effects.

Model-based efficiency mapping and parametric analysis of low-pressure axial fans

This paper advances a methodology for axial fan efficiency mapping followed by a design optimization exercise of a low-pressure axial fan for small capacity refrigeration applications. For these purposes, a tailor-made first-principles simulation model based on the so-called blade element theory (BET) was put forward. First, the fan efficiency was deployed into two terms – namely, electric motor and blade efficiency, which in turn was split into two other terms that account not only for the irreversible losses but also for flow maldistribution – in order to identify opportunities for blade optimization. Later, a sensitivity analysis was performed to find out the optimum values of key operating and design parameters of the fan, namely motor speed, blade size and number, chord length, pitch angle, and airfoil characteristics, such as thickness and maximum camber values. Among those, the pitch angle stood out as the most influencing parameter affecting the fan characteristics, including the airflow rate, the power consumption, and the blade efficiency. Comparisons with results obtained by means of the so-called fan laws are also reported for the blade size and speed.

Exploring the Planning and Configuration of the Hospital Wayfinding System by Space Syntax: A Case Study of Cheng Ching Hospital, Chung Kang Branch in Taiwan

With regard to the outpatient areas of a hospital, the smoothness of the route is now taken into consideration in the process of configuring the wayfinding system. As patients often spend time on ineffective wayfinding processes, and there is limited manpower at hospitals and a lack of clarity in the information provided by the wayfinding system, it is difficult to provide effective and timely consultation services for patients. This study was conducted at Cheng Ching Hospital, Chung Kang Branch (CCH/CKB) in Taiwan. This study attempts to investigate the relationships between the wayfinding system of the outpatient areas and the patients’ behaviors in the hospital. Depthmap software based on space syntax is adopted to assist in the route analysis and wayfinding behaviors. It integrates axial mapping analysis and isovist analysis and gives suggestions on the location, format and content of the wayfinding system. The final results of the study show that in the wayfinding task experiment gender has no significant impact on the effect of wayfinding efficiency, while a significant difference is found for age. Older people need more time to complete the wayfinding task, which means that they have poorer performance in wayfinding efficiency. The analysis of the results of space syntax shows that a good wayfinding system should be a symmetric tree-branch structure rather than circular structure in a medical building, that areas where it is easy to become lost should have a clear signage guiding system planning and configuration, and that clear guidance information should be provided to the patients to achieve the goal of saving consultation time and improving the quality of the medical environment.

Startup Test Plan and Predictions for Highly Enriched Uranium to Low-Enriched Uranium Fuel Conversion at the University of Missouri Research Reactor

Nonpower reactors licensed by the U.S. Nuclear Regulatory Commission require a startup test plan as part of any facility modification to verify operability prior to resumption of operations. In order to support conversion of the University of Missouri Research Reactor from the use of highly enriched uranium to low-enriched uranium (LEU) fuel, a startup test plan has been devised to measure certain reactor physics parameters for the initial all-fresh LEU core licensing documentation that will be submitted. These parameters include the approach to critical, primary coolant void coefficient of reactivity, flux trap void coefficient of reactivity, determination of flux trap sample reactivity worth, radial and axial thermal neutron flux mapping, control blade worth calibration, primary and pool coolant temperature coefficient of reactivity, and flux mapping of experimental positions. In this paper, predictions for these parameters made using the Monte Carlo N-Particle Version 5 (MCNP5) radiation transport code are reported. These predictions will support the startup tests by providing a baseline set of expectations and additional insight into the performance of the LEU core.

Effect of combustion zone material on the thermal performance of a biogas-fuelled porous media burner: Experimental studies

The performance of a porous media burner (PMB) is immensely dependent on the selection of porous material. Present experimental work investigates the impact of burner’s material on the thermal performance of a crude biogas-fuelled, in house developed PMB. This includes the study of burner stable operating limits, location of reaction zone, estimation of radiation efficiency and exhaust gas emission analysis. The PMB consists of two sections of porous material, one is the combustion zone and the other is the preheat zone. In the present research, the impact of combustion zone material on performance of the PMB is tested, while keeping the material of preheat zone unchanged. Silicon carbide (SiC) and zirconia (ZrO2) foams, both having porosity of 10 ppi, have been chosen as combustion zone. Experimental investigation shows that for the whole input load range of 5–10 kW, the SiC foam offered lean working condition, while in case of ZrO2, similar condition was limited to 5–8 kW. Within these stable operating limits, the axial temperature mapping of the burner highlights the location of reaction zone. Combustion in SiC foam is found to offer higher radiation efficiency of maximum 23.7%, as compared to that of ZrO2, where it is only 8%. Exhaust gas analysis shows that CO and NOx concentrations of both burners were low and the maximum values were limited to 156 ppm and 20 ppm, respectively. Overall performance assessment confirms that SiC is a better choice over ZrO2 for lean combustion of crude biogas in the developed PMB.

ROLE OF MRI T2 MAPPING IN ASSESSMENT OF ARTICULAR KNEE CARTILAGE IN OSTEOARTHRITIS

Background: T2 mapping of hyaline cartilage is an imaging technique for the qualitative and quantitative detection of thecartilage providing convincing color mapping and quantitative detection of the cartilage mainly regarding architecture and changes in water content, proteoglycan, and collagen matrix ultra-structure associated with early cartilage degeneration.Aim Of Work: This work aims at elucidating the role of MRI complementary T2 mapping in assessment of articular knee cartilage for improving sensitivity of early detection of Osteoarthritis. Also, compare the articular cartilage T2 relaxation values in normal subjects and patients with osteoarthritis. Patients And Methods: This prospective case-control study wasapproved by the Ethical Committee of Scientific Research in Ain Shams University, and the informed consent was obtained. The material of this study included sixty (60) subjects, divided into two groups, 50 patients (symptomatic group: 33 men and 17 women) with clinical evidence of osteoarthritis, and 10 normal control group (asymptomatic group 8 men and 2 women) were included in this study, with their ages ranged between 19-75 years. All patients and controls underwent MR imaging of the knee joint. MR imaging was performed at 1.5 Tesla by using a routine protocol with the addition of a sagittal, coronal, or axial T2 mapping sequence or all. The standard imaging planes of the knee were evaluated with articular cartilage assessment as intact or not. Thereafter, these standard planes were evaluated together with T2 maps and articular cartilage was again assessed as of normal (<48ms) or elevated (≥48ms) T2 value in terms of milliseconds. Generalized estimating equation models were used to compare the sensitivity and specificity of the routine MR imaging protocol and T2 maps. Results: Both sensitivities and specificities were 82% and 100%, respectively, for the routine MR protocol alone and 100% and 90% after the addition of the T2 mapping to the routine MR protocol. The addition of T2 maps to the routine MR imaging protocol significantly improved the sensitivity (Binary Diagnostic test, p = 0.01). AComparison between patients and controls as regards T2 values showed a highly statistically significant difference (Independent TTest, P<0 .001). Conclusion: A combination of both morphological and T2 mapping MRI, together with clinical evaluation represents a desirable multi-modal approach to the diagnosis of osteoarthritis. T2 mapping, as a biochemically sensitive MRI sequence of the knee improves sensitivity from 82% to 100% to detect early structural degeneration with better diagnostic information in the knee articular cartilage.

Potential predictive value of axial T2 mapping at 3 Tesla MRI in patients with untreated patellar cartilage defects over a mean follow-up of four years

The objective was to demonstrate the potential of axial T2 mapping for quantification of untreated early-stage patellar cartilage lesions over time and to assess its capability as a potential predictive marker for future progression. Thirty patients (mean age, 36.7±11.1 years; 16 males), with early-stage patellar cartilage defects (≤ICRS grade 2) at baseline and no treatment during follow up (4.0±1.6 years) were enrolled. Morphological cartilage changes over time were subdivided into a Progression, Non-Progression Group and Regression Group. Quantitative analysis of cartilage defects and healthy reference was performed by means of global and zonal T2 mapping (deep and superficial cartilage T2 values) at both time points. Statistical evaluation included analysis of variance (ANOVA), paired t Test's and ROC analysis. The Progression Group (N=11) had significantly higher global T2 values at baseline (57.4±7.8ms) than patients without (N=17) (40.6±6.9ms) (P<0.01). Furthermore the Non-Progression Group showed only a minor increase in global T2 relaxation times to 43.1±7.9ms (P=0.07) at follow up, whereas in the progression group global (68,7±19ms: P=0.02) and superficial T2 values (65,8±8.2-79.8±24.4ms; P=0.03) increased significantly. T2 values for healthy reference cartilage remained stable. In 2 patients an improvement in ICRS grading was observed (Regression Group) with decreasing T2 values. The ROC analysis showed an area under the curve of 0.92 (95%CI 0.82-1.0). At a cut-off value of 47.15ms, we found a sensitivity of 92% (false-positive rate of 18%) for future progression of cartilage defects. This study provides evidence regarding the possible potential of axial T2 mapping as a tool for quantification and prediction of patellar cartilage defect progression in untreated defects.

Association between native T1 mapping of the kidney and renal fibrosis in patients with IgA nephropathy

IntroductionIgA nephropathy (IgAN) is the commonest global cause of glomerulonephritis. Extent of fibrosis, tubular atrophy and glomerulosclerosis predict renal function decline. Extent of renal fibrosis is assessed with renal biopsy which is invasive and prone to sampling error. We assessed the utility of non-contrast native T1 mapping of the kidney in patients with IgAN for assessment of renal fibrosis.MethodsRenal native T1 mapping was undertaken in 20 patients with IgAN and 10 healthy subjects. Ten IgAN patients had a second scan to assess test-retest reproducibility of the technique. Native T1 times were compared to markers of disease severity including degree of fibrosis, eGFR, rate of eGFR decline and proteinuria.ResultsAll patients tolerated the MRI scan and analysable quality T1 maps were acquired in at least one kidney in all subjects. Cortical T1 times were significantly longer in patients with IgAN than healthy subjects (1540 ms ± 110 ms versus 1446 ± 88 ms, p = 0.038). There was excellent test-retest reproducibility of the technique, with Coefficient-of-variability of axial and coronal T1 mapping analysis being 2.9 and 3.7% respectively. T1 correlated with eGFR and proteinuria (r = − 0.444, p = 0.016; r = 0.533, p = 0.003 respectively).Patients with an eGFR decline > 2 ml/min/year had increased T1 times compared to those with a decline < 2 ml/min/year (1615 ± 135 ms versus 1516 ± 87 ms, p = 0.068), and T1 time was also higher in patients with a histological ‘T’-score of > 0, compared to those with a ‘T’-score of 0 (1575 ± 106 ms versus 1496 ± 105 ms, p = 0.131), though not to significance.ConclusionsCortical native T1 time is significantly increased in patients with IgAN compared to healthy subjects and correlates with markers of renal disease. Reproducibility of renal T1 mapping is excellent. This study highlights the potential utility of native T1 mapping in IgAN and other progressive nephropathies, and larger prospective studies are warranted.

Correlation between cell wall buckling and deformation banding in a closed-cell foam

We investigate deformation dynamics in a widely used closed-cell foam of polymethacrylimide under uniaxial compression with in situ X-ray computed tomography and digital volume correlation. Axial strain mapping demonstrates discrete deformation bands nucleated in sequence across the sample. A buckling strength index is proposed to quantify the buckling resistance of cell walls, based on their morphology extracted via an edge-segmentation procedure developed in this work. The spatial distribution of the weakest cell walls is correlated well with the location and nucleation sequence of deformation bands, and can be used for predicting deformation banding.

A Case of Infarcted Localized Tenosynovial Giant Cell Tumor of the Knee: Multimodality Imaging Features and Literature Review

: Localized tenosynovial giant cell tumor (L-TGCT), formerly called giant cell tumor of the tendon sheath, is one of the benign proliferative diseases of the synovium of a joint, bursa, or tendon sheath. L-TGCT occasionally involves a large joint such as the knee, and rarely it is combined with infarction by pedicle torsion. Neither the prevalence of torsion of L-TGCT nor the mechanism involved are known, but it is thought to be uncommon progress. Herein, we describe a rare case of infarcted L-TGCT in the knee involving torsion of a mass pedicle in a 47-year-old man. We utilized magnetic resonance imaging including diffusion-weighted imaging and axial apparent diffusion mapping, and sonographic appearance during the course of investigations, because radiologic findings showed characteristic features of infarcted L-TGCT.

In situ and Operando Raman Spectroscopy of Layered Transition Metal Oxides for Li-ion Battery Cathodes

In situ and operando Raman spectroscopy is proposed to provide unique means for deeper fundamental understanding and further development of layered transition metal LiMO2 (M=Ni,Co,Mn) oxides suitable for Li-ion battery applications. We compare several spectro-electrochemical cell designs and suggest key experimental parameters for obtaining optimum electrochemical performance and spectral quality. Studies of the most practically relevant LiMO2 compositions are exemplified with particular focus on two experimental approaches: (1) lateral and axial Raman mapping of the electrode’s (near-) surface to monitor inhomogeneous electrode reactions and (2) time-dependent single-particle spectra during cycling to analyze the LixMO2 lattice dynamics as a function of lithium content. Raman Spectroscopy is claimed to provide a unique real-time probe of the M-O bonds, which are at the heart of the electrochemistry of LiMO2 oxides and govern their stability. We highlight the need for further fundamental understanding of the relationships between the spectroscopic response and oxide lattice structure with particular emphasis on the development of a theoretical framework linking the position and intensity of the Raman bands to the local LixMO2 lattice configuration. The use of complementary experimental techniques and model systems for validation also deserve further attention. Several novel LiMO2 compositions are currently being explored, especially containing dopings and coatings, and Raman Spectroscopy could offer a highly dynamic and convenient tool to guide the formulation of high specific charge and long cycle life LiMO2 oxides for next-generation Li-ion battery cathodes.

Two and Three-Dimensional CT Mapping of Hoffa Fractures.

Hoffa fractures, coronal-plane fractures involving the distal femoral condyles, are unstable, intra-articular fractures. The aim of this study was to define the location and frequency of fracture lines and comminution zones in Hoffa fractures using computed tomography (CT) mapping in both 2-dimensional and 3-dimensional contexts. Seventy-five Hoffa fractures (OTA/AO types 33B3.2 and 33B3.3) were retrospectively reviewed. The directions of fracture lines were characterized in the axial and sagittal CT planes. CT images for all fractures were superimposed on one another and oriented to fit a standard template. Mapping of fracture lines and comminution zones in both the axial and sagittal planes was performed. A 3-dimensional map was created by reducing reconstructed fracture fragments to fit to a model of the distal aspect of the femur. This study included 1 bicondylar and 74 unicondylar (26 medial and 48 lateral) Hoffa fractures. Comminuted fractures accounted for 35.5% of all fractures and 44.9% of lateral fractures. Axial fracture mapping demonstrated that fracture lines were concentrated in the middle-third area of the lateral condyle but were less concentrated and with greater variation in the medial condyle. The mean angle of fracture lines with respect to the posterior condylar axis was 34.4° and 29.0° in the lateral and medial femoral condyles, respectively. Sagittal fracture mapping also demonstrated that fracture lines were concentrated in the middle third of the lateral condyle but were less concentrated in the medial condyle. The mean angle of fracture lines with respect to the posterior cortex of the distal femoral shaft was 23.1° and 19.3° in the lateral and medial condyles, respectively. Three-dimensional mapping demonstrated comminution zones commonly occurring in the weight-bearing zone of the lateral condylar articular surface. Hoffa fractures occurred more frequently in the lateral femoral condyle. In the axial plane, fractures commonly extended from anterolateral to posteromedial in the lateral condyle and from anteromedial to posterolateral in the medial femoral condyle. In the sagittal plane, fractures traversed from anteroinferior to posterosuperior. Articular comminution was more commonly seen in lateral condylar fractures and concentrated in the weight-bearing zone of the articular surface. Research in this area is imperative for optimal preoperative planning, such as for the selection of surgical approach and fixation constructs. Our findings lend insight into fracture morphology, which can assist with fracture classification and the design of biomechanical studies, ultimately aiding in treatment.

Correlation study between facet joint cartilage and intervertebral discs in early lumbar vertebral degeneration using T2, T2* and T1ρ mapping.

Recent advancements in magnetic resonance imaging have allowed for the early detection of biochemical changes in intervertebral discs and articular cartilage. Here, we assessed the feasibility of axial T2, T2* and T1ρ mapping of the lumbar facet joints (LFJs) to determine correlations between cartilage and intervertebral discs (IVDs) in early lumbar vertebral degeneration. We recruited 22 volunteers and examined 202 LFJs and 101 IVDs with morphological (sagittal and axial FSE T2-weighted imaging) and axial biochemical (T2, T2* and T1ρ mapping) sequences using a 3.0T MRI scanner. IVDs were graded using the Pfirrmann system. Mapping values of LFJs were recorded according to the degeneration grades of IVDs at the same level. The feasibility of T2, T2* and T1ρ in IVDs and LFJs were analyzed by comparing these mapping values across subjects with different rates of degeneration using Kruskal-Wallis tests. A Pearson’s correlation analysis was used to compare T2, T2* and T1ρ values of discs and LFJs. We found excellent reproducibility in the T2, T2* and T1ρ values for the nucleus pulposus (NP), anterior and posterior annulus fibrosus (PAF), and LFJ cartilage (intraclass correlation coefficients 0.806–0.955). T2, T2* and T1ρ mapping (all P<0.01) had good Pfirrmann grade performances in the NP with IVD degeneration. LFJ T2* values were significantly different between grades I and IV (PL = 0.032, PR = 0.026), as were T1ρ values between grades II and III (PL = 0.002, PR = 0.006) and grades III and IV (PL = 0.006, PR = 0.001). Correlations were moderately negative for T1ρ values between LFJ cartilage and NP (rL = −0.574, rR = −0.551), and between LFJ cartilage and PAF (rL = −0.551, rR = −0.499). T1ρ values of LFJ cartilage was weakly correlated with T2 (r = 0.007) and T2* (r = −0.158) values. Overall, we show that axial T1ρ effectively assesses early LFJ cartilage degeneration. Using T1ρ analysis, we propose a link between LFJ degeneration and IVD NP or PAF changes.

Quantitative Analysis of Disc Degeneration Using Axial T2 Mapping in a Percutaneous Annular Puncture Model in Rabbits.

ObjectiveTo evaluate T2 relaxation time change using axial T2 mapping in a rabbit degenerated disc model and determine the most correlated variable with histologic score among T2 relaxation time, disc height index, and Pfirrmann grade.Materials and MethodsDegenerated disc model was made in 4 lumbar discs of 11 rabbits (n = 44) by percutaneous annular puncture with various severities of an injury. Lumbar spine lateral radiograph, MR T2 sagittal scan and MR axial T2 mapping were obtained at baseline and 2 weeks and 4 weeks after the injury in 7 rabbits and at baseline and 2 weeks, 4 weeks, and 6 weeks after the injury in 4 rabbits. Generalized estimating equations were used for a longitudinal analysis of changes in T2 relaxation time in degenerated disc model. T2 relaxation time, disc height index and Pfirrmann grade were correlated with the histologic scoring of disc degeneration using Spearman's rho test.ResultsThere was a significant difference in T2 relaxation time between uninjured and injured discs after annular puncture. Progressive decrease in T2 relaxation time was observed in injured discs throughout the study period. Lower T2 relaxation time was observed in the more severely injured discs. T2 relaxation time showed the strongest inverse correlation with the histologic score among the variables investigated (r = -0.811, p < 0.001).ConclusionT2 relaxation time measured with axial T2 mapping in degenerated discs is a potential method to assess disc degeneration.

Inter- and intra-rater reliability of patellofemoral kinematic and contact area quantification by fast spin echo MRI and correlation with cartilage health by quantitative T1ρ MRI

BackgroundPatellar maltracking is a leading cause of patellofemoral pain syndrome (PFPS). The aim of this study was to determine the inter- and intra-rater reliability of a semi-automated program for magnetic resonance imaging (MRI) based patellofemoral kinematics. MethodsSixteen subjects (10 with PFPS [mean age 32.3; SD 5.2; eight females] and six controls without PFPS 19 [mean age 28.6; SD 2.8; three females]) participated in the study. One set of T2-weighted, fat-saturated fast spin-echo (FSE) MRIs were acquired from each subject in full extension and 30° of knee flexion. MRI including axial T1ρ relaxation time mapping sequences was also performed on each knee. Following image acquisitions, regions of interest for kinematic MRI, and patellar and trochlear cartilage were segmented and quantified with in-house designed spline- based MATLAB semi-automated software. ResultsIntraclass Correlations Coefficients (ICC) of calculated kinematic parameters were good to excellent, ICC > 0.8 in patellar flexion, rotation, tilt, and translation (anterior -posterior, medial -lateral, and superior -inferior), and contact area translation. Only patellar tilt in the flexed position and motion from extended to flexed state was significantly different between PFPS and control patients (p=0.002 and p=0.006, respectively). No significant correlations were identified between patellofemoral kinematics and contact area with T1ρ relaxation times. ConclusionsA semi-automated, spline-based kinematic MRI technique for patellofemoral kinematic and contact area quantification is highly reproducible with the potential to help better understand the role of patellofemoral maltracking in PFPS and other knee disorders. Level of EvidenceLevel IV