Reducing susceptibility artefacts in magnetic resonance images of the canine stifle following surgery for cranial cruciate ligament deficiency

2012 ◽  
Vol 25 (06) ◽  
pp. 488-497 ◽  
Author(s):  
J. Grierson ◽  
C. R. Lamb ◽  
F. H. David
Keyword(s):  
Magnetic Resonance ◽  
Tibial Plateau ◽  
Cruciate Ligament ◽  
Magnetic Resonance Images ◽  
Proton Density ◽  
Mr Images ◽  
Cranial Cruciate Ligament ◽  
Metallic Implants ◽  
Image Ranking ◽  
Canine Stifle

SummaryBackground: Magnetic resonance (MR) images of the postoperative canine stifle are adversely affected by susceptibility artefacts associated with metallic implants.Objectives: To determine empirically to what extent susceptibility artefacts could be reduced by modifications to MR technique.Methods: Three cadaveric limbs with a tibial plateau levelling osteotomy (TPLO), tibial tuberosity advancement (TTA), or extra-capsular stabilization (ECS) implant, respectively, were imaged at 1.5T. Series of proton density and T2-weighted images were acquired with different combinations of frequency-encoding gradient (FEG) direction and polarity, stifle flexion or extension, echo spacing (ES), and readout bandwidth (ROBW), and ranked. The highest rank (a rank of 1) corresponded to the smallest artefact.Results: Image ranking was affected by FEG polarity (p = 0.005), stifle flexion (p = 0.01), and ROBW (p = 0.0001). For TPLO and TTA implants, the highest ranked images were obtained with the stifle flexed, lateromedial FEG, and medial polarity for dorsal images, and craniocaudal FEG and caudal polarity for sagittal images. For the ECS implant, the highest ranked images were obtained with the stifle extended, a proximodistal FEG and proximal polarity for dorsal images, and craniocaudal FEG and cranial polarity for sagittal images.Clinical significance: Susceptibility artefacts in MR images of postoperative canine stifles do not preclude clinical evaluation of joints with ECS or TTA implants.Part of this study was presented at the Annual Meeting of the American College of Veterinary Radiology, Albuquerque, NM, October 2011.

scholarly journals Tibial Plateau Slopes in Indian Patients with or without Anterior Cruciate Ligament Injury: A Magnetic Resonance Imaging Study

2016 ◽  
Vol 24 (3) ◽  
pp. 289-293 ◽  
Author(s):  
Shyam Sundar ◽  
Sarthak Patnaik ◽  
Bobur Ubaydullaev ◽  
Vinodh Kolandavelu ◽  
David Rajan
Keyword(s):  
Anterior Cruciate Ligament ◽  
Magnetic Resonance ◽  
Tibial Plateau ◽  
Cruciate Ligament ◽  
Acl Injury ◽  
Magnetic Resonance Images ◽  
Lateral Tibial Plateau ◽  
Indian Patients ◽  
Males And Females ◽  
Anterior Cruciate

Purpose To compare anterior cruciate ligament (ACL)–injured and ACL-intact patients as well as males and females in terms of tibial plateau slopes to determine their association with ACL injury. Methods Magnetic resonance images (MRI) of the knee of 310 male and 179 female skeletally mature Indian patients (mean age, 40 years) with (n=170+29) or without (n=140+150) ACL injury were reviewed. Their medial and lateral tibial plateau slopes (MTPS and LTPS), medial tibial plateau depth (MTPD), and lateral tibial plateau height (LTPH) were measured using MRI. Results The ACL-injured and ACL-intact groups were comparable in terms of MTPS (6.72° vs. 6.73°, p=0.07), LTPS (5.68° vs. 5.70°, p=0.09), MTD (1.74 vs. 1.73 mm, p=0.356), and LTH (2.21 vs. 2.22 mm, p=0.393). Males and females were also comparable in terms of MTPS and LTPS in both ACL-injured and ACL-intact groups. Conclusion ACL-injured and ACL-intact patients as well as males and females were comparable in terms of the tibial plateau slope parameters.

Magnetic resonance imaging for detection of late meniscal tears in dogs following tibial tuberosity advancement for treatment of cranial cruciate ligament injury

2014 ◽  
Vol 27 (02) ◽  
pp. 141-146 ◽  
Author(s):  
C. R. Lamb ◽  
M. S. Tivers ◽  
A. Li ◽  
F. Taylor-Brown
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Cruciate Ligament ◽  
Meniscal Tear ◽  
Ligament Injury ◽  
Meniscal Tears ◽  
Resonance Imaging ◽  
Mr Images ◽  
Cranial Cruciate Ligament

SummaryTo document the use of and to estimate the accuracy of magnetic resonance (MR) imaging for detection of late meniscal tears in dogs with cranial cruciate ligament injury treated with tibial tuberosity advancement (TTA).Medical records of dogs that had TTA followed by stifle MR imaging for suspected meniscal tear and subsequent arthrotomy were reviewed retrospectively. Magnetic resonance images were reviewed independently by an observer blinded to clinical information who classified menisci as torn, abnormal but intact, or normal. Magnetic resonance and surgical findings were compared.Eight stifles from large breed dogs were included. Six stifles had a medial meniscal tear identified in MR images and later confirmed surgically. In the remaining two stifles, the menisci appeared intact in MR images and no tear was identified at subsequent arthrotomy. Lateral menisci in all stifles appeared intact in MR images and were considered normal at surgery. Susceptibility artefacts associated with TTA implants were present in all images but did not adversely affect interpretation of intra-articular structures.Magnetic resonance imaging appears to be accurate for diagnosis of late meniscal tears. Artefacts associated with TTA implants did not prevent evaluation of critical intra-articular structures. Further investigation with MR imaging should be considered when late meniscal tear is suspected following TTA.

Sagittal joint instability in the cranial cruciate ligament insufficient canine stifle

2014 ◽  
Vol 42 (03) ◽  
pp. 151-156 ◽  
Author(s):  
J. Rey ◽  
M. S. Fischer ◽  
P. Böttcher
Keyword(s):  
Tibial Plateau ◽  
Cruciate Ligament ◽  
Wedge Osteotomy ◽  
Motion Pattern ◽  
Cranial Cruciate Ligament ◽  
Sound Control ◽  
In Vitro Simulation ◽  
Canine Stifle

Summary Objective: This in vivo study qualitatively describes the sagittal motion pattern of the cranial cruciate ligament (CrCL) insufficient canine stifle in operated and unoperated joints with cranio-caudal laxity on palpation. Material and methods: Sagittal stifle kinematics were recorded in vivo in dogs (> 15 kg BW) with unilateral (n = 7) or bilateral (n = 6) complete CrCL rupture and positive cranial drawer test as well as two sound control dogs using uniplanar fluoroscopic kinematography with the dogs walking on a treadmill. Stifle stability and sagittal motion pattern of the femur and the tibia were determined by visual inspection of the fluoroscopic video sequences. Results: Control dogs showed no cranio-caudal instability, identical to the contralateral stifles of the dogs with unilateral rupture. All unoperated stifles with CrCL rupture (n = 6) showed caudal slippage of the femur at the beginning of the stance phase. Of the 13 operated stifles (TightRope: n = 1, tibial tuberosity advancement, TTA: n = 6, tibial plateau leveling osteotomy, TPLO: n = 5, cranial closing wedge osteotomy, CCWO: n = 1) nine were unstable, showing the same motion pattern as the unoperated stifles. Conclusion: In the CrCL insufficient stifle with in vivo cranio-caudal instability caudal slippage of the distal femur at tow touch is the predominant motion pattern. Clinical significance: The discrepancy between in vivo motion pattern and in vitro simulation of CrCL insufficiency in which cranial tibial subluxation is the predominant sagittal motion pattern warrants further studies.

scholarly journals Automated Head Tissue Modelling Based on Structural Magnetic Resonance Images for Electroencephalographic Source Reconstruction

2021 ◽  
Author(s):  
Gaia Amaranta Taberna ◽  
Jessica Samogin ◽  
Dante Mantini
Keyword(s):  
Magnetic Resonance ◽  
Brain Structures ◽  
Magnetic Resonance Images ◽  
Head Model ◽  
Source Reconstruction ◽  
Mr Images ◽  
Tissue Segmentation ◽  
Mr Image ◽  
Eeg Recordings ◽  
Tissue Modelling

AbstractIn the last years, technological advancements for the analysis of electroencephalography (EEG) recordings have permitted to investigate neural activity and connectivity in the human brain with unprecedented precision and reliability. A crucial element for accurate EEG source reconstruction is the construction of a realistic head model, incorporating information on electrode positions and head tissue distribution. In this paper, we introduce MR-TIM, a toolbox for head tissue modelling from structural magnetic resonance (MR) images. The toolbox consists of three modules: 1) image pre-processing – the raw MR image is denoised and prepared for further analyses; 2) tissue probability mapping – template tissue probability maps (TPMs) in individual space are generated from the MR image; 3) tissue segmentation – information from all the TPMs is integrated such that each voxel in the MR image is assigned to a specific tissue. MR-TIM generates highly realistic 3D masks, five of which are associated with brain structures (brain and cerebellar grey matter, brain and cerebellar white matter, and brainstem) and the remaining seven with other head tissues (cerebrospinal fluid, spongy and compact bones, eyes, muscle, fat and skin). Our validation, conducted on MR images collected in healthy volunteers and patients as well as an MR template image from an open-source repository, demonstrates that MR-TIM is more accurate than alternative approaches for whole-head tissue segmentation. We hope that MR-TIM, by yielding an increased precision in head modelling, will contribute to a more widespread use of EEG as a brain imaging technique.

scholarly journals Multigrid Nonlocal Gaussian Mixture Model for Segmentation of Brain Tissues in Magnetic Resonance Images

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Yunjie Chen ◽  
Tianming Zhan ◽  
Ji Zhang ◽  
Hongyuan Wang
Keyword(s):  
Magnetic Resonance ◽  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Gaussian Mixture ◽  
Magnetic Resonance Images ◽  
Intensity Inhomogeneity ◽  
Mr Images ◽  
Proposed Model ◽  
Brain Mr Images ◽  
The Impact

We propose a novel segmentation method based on regional and nonlocal information to overcome the impact of image intensity inhomogeneities and noise in human brain magnetic resonance images. With the consideration of the spatial distribution of different tissues in brain images, our method does not need preestimation or precorrection procedures for intensity inhomogeneities and noise. A nonlocal information based Gaussian mixture model (NGMM) is proposed to reduce the effect of noise. To reduce the effect of intensity inhomogeneity, the multigrid nonlocal Gaussian mixture model (MNGMM) is proposed to segment brain MR images in each nonoverlapping multigrid generated by using a new multigrid generation method. Therefore the proposed model can simultaneously overcome the impact of noise and intensity inhomogeneity and automatically classify 2D and 3D MR data into tissues of white matter, gray matter, and cerebral spinal fluid. To maintain the statistical reliability and spatial continuity of the segmentation, a fusion strategy is adopted to integrate the clustering results from different grid. The experiments on synthetic and clinical brain MR images demonstrate the superior performance of the proposed model comparing with several state-of-the-art algorithms.

Conformation of the proximal tibia and cranial cruciate ligament disease in small breed dogs

2017 ◽  
Vol 30 (03) ◽  
pp. 178-183 ◽  
Author(s):  
Michal Kyllar ◽  
Duncan Midgley ◽  
Martin Owen ◽  
Jan Janovec
Keyword(s):  
Body Weight ◽  
Clinical Significance ◽  
Tibial Plateau ◽  
Proximal Tibia ◽  
Cruciate Ligament ◽  
Tibial Tuberosity ◽  
Cranial Cruciate Ligament ◽  
Relative Body Weight ◽  
Cranial Cruciate Ligament Disease ◽  
Small Breed

SummaryObjectives: To investigate the conformation of the proximal tibia in small breed dogs with and without cranial cruciate ligament disease (CCLD) and to identify morphologic abnormalities that may predispose to development of CCLD.Methods: Mediolateral radiographs of the entire tibia of dogs <15 kg with surgically confirmed CCLD were retrospectively evaluated. Proximal tibial width (PTW), tibial plateau length (TPL), tibial plateau angle as described by Slocum and Slocum (sTPA), proximal tibial tuberosity angle (PTTA), tibial plateau angle as described by Inauen and colleagues (nTPA), and diaphyseal tibial width (DTW) were measured. The same variables were obtained from mediolateral radiographs of the entire tibia of dogs <15 kg without CCLD. In addition, a quotient nTPA/ PTW, relative tibial tuberosity width (rTTW), and relative body weight (rBW) were calculated for each dog. Independent two-sample t-test (p = 0.05) was used to compare mean ± SD of all measured variables between the two groups.Results: Gender, age, and weight mean ± SD were not significantly different between the two groups of dogs (p <0.05). Dogs with CCLD had significantly greater sTPA (p = 0.015) and rBW (p = 0.016).Clinical significance: In dogs of small breeds, a combination of an excessively steep tibial plateau and an increased relative body weight may predispose to early CCLD development. The slope of the tibial plateau was found to be caused by an abnormal caudal angulation of the proximal tibia, a phenomenon previously associated with CCLD development in small breed dogs in individual cases.

Measurement of the tibial plateau angle in cats with and without cranial cruciate ligament rupture

2009 ◽  
Vol 22 (02) ◽  
pp. 83-86 ◽  
Author(s):  
S. Reese ◽  
K. Lorinson ◽  
D. Lorinson ◽  
E. Schnabl
Keyword(s):  
Tibial Plateau ◽  
Cruciate Ligament ◽  
Degenerative Joint Disease ◽  
Joint Disease ◽  
Cranial Cruciate Ligament ◽  
Ligament Rupture ◽  
Cruciate Ligament Rupture ◽  
Inter Observer Variability ◽  
Measurement Results ◽  
Cranial Cruciate Ligament Rupture

SummaryThe objective of the present study was to determine the tibial plateau angle (TPA) in cats without stifle pathology and to compare it with cats suffering from an isolated cranial cruciate ligament rupture. Mediolateral radiographs of the stifle were taken and the tibial plateau angle was measured based on the method previously described by Slocum and Devine (1983) for dogs. Three observers with different levels of experience evaluated the radiographs of all of the cats in this study. The mean tibial plateau angle measured by all three observers in the cats with a rupture of the cranial cruciate ligament (CCL) was 3.1° greater than in cats without stifle pathology. Neither gender, age, body weight nor degenerative joint disease had an influence on measurement results. The authors found an inter-observer variability of ± 5.3°. Hence it can be concluded that cats with cranial cruciate ligament rupture have a greater TPA, and this at least lends some credence to the possibility of higher TPA being a predis-posing factor for cruciate injury in this species.

scholarly journals Use of castor bean polymer in developing a new technique for tibial tuberosity advancement for cranial cruciate ligament rupture correction in dogs

2016 ◽  
Vol 61 (No. 7) ◽  
pp. 382-388 ◽  
Author(s):  
RM Medeiros ◽  
MAM Silva ◽  
PPM Teixeira ◽  
LGGG Dias ◽  
DG Chung ◽  
...  
Keyword(s):  
Ricinus Communis ◽  
Cruciate Ligament ◽  
The Body ◽  
Tibial Tuberosity ◽  
Osteotomy Site ◽  
Cranial Cruciate Ligament ◽  
Time Points ◽  
Metallic Implants ◽  
A New Technique ◽  
Distal Fixation

The purpose of the current study was to develop a new tibial tuberosity advancement (TTA) technique, by replacing the original titanium cage with a Ricinus communis polyurethane resin-made wedge polymer. The implants were manufactured using the same size and angles of the original titanium cages, though larger distally. The modified TTA technique (TTAm) was performed in 42 knees of 35 dogs diagnosed with rupture of the cranial cruciate ligament (RCCL). Animals were submitted to radiographic and gait assessments preoperatively, early postoperatively and following 30, 60, 90 and 120 days. All animals exhibited good clinical outcome. There were no cases of impaired healing or bone resorption until 120 days postoperatively and there was no patient with patellar distress after TTAm. Scores of gait evaluation revealed differences between time points. There were also differences between the evaluations of control and pre- and post-operative times. However, there was no difference among the assessment of 30 days and the following time points. The use of the polyurethane polymer for TTAm was advantageous, not only due to biocompatibility and osseointegration, but also for providing easy handling; it can be moulded intra-operatively if necessary. Moreover, it allows precise adaptation to the osteotomy site, as opposed to the original TTA metallic implants, which cannot be moulded. It is suggested that incision lengths for TTAm are slightly shorter than those required for the conventional TTA as this requires the distal fixation of the plate at the beginning of the middle third of the body of the tibia. The TTAm does not require the use of fixation plates and it is performed only at the cranial aspect of the tibia. The method of attachment of the tibial tuberosity in the craniocaudal direction was effective. The setting associated with the use of the polyurethane polymer allowed simplification of the technique for easier implementation, and the amount of implant material required to perform TTAm was reduced in comparison to the conventional TTA. This technique can be used for treating the knees of dogs with RCCL, and provides for easy execution, less invasiveness to the tissues of the knee joint and more versatility in comparison to conventional TTA.

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