MRI Imaging Sequences Research Articles

Cerebrovascular reactivity (CVR) MRI with CO2 challenge: A technical review

Cerebrovascular reactivity (CVR) is an indicator of cerebrovascular reserve and provides important information about vascular health in a range of brain conditions and diseases. Unlike steady-state vascular parameters, such as cerebral blood flow (CBF) and cerebral blood volume (CBV), CVR measures the ability of cerebral vessels to dilate or constrict in response to challenges or maneuvers. Therefore, CVR mapping requires a physiological challenge while monitoring the corresponding hemodynamic changes in the brain. The present review primarily focuses on methods that use CO2 inhalation as a physiological challenge while monitoring changes in hemodynamic MRI signals. CO2 inhalation has been increasingly used in CVR mapping in recent literature due to its potency in causing vasodilation, rapid onset and cessation of the effect, as well as advances in MRI-compatible gas delivery apparatus. In this review, we first discuss the physiological basis of CVR mapping using CO2 inhalation. We then review the methodological aspects of CVR mapping, including gas delivery apparatus, the timing paradigm of the breathing challenge, the MRI imaging sequence, and data analysis. In addition, we review alternative approaches for CVR mapping that do not require CO2 inhalation.

Automatic system for estimating the volume of the left ventricle based on two-dimensional MRI images of the heart along the long axis

The article is devoted to the development of a system that allows automatic estimation of systole, diastole and left ventricular ejection fraction of the heart based on the sequence of MRI images from the apical two-chamber and four-chamber positions. The implemented system was tested on the images of the heart of 200 patients, and its accuracy and operability was assessed.

A Meshfree Representation for Cardiac Medical Image Computing

The prominent advantage of meshfree method, is the way to build the representation of computational domain, based on the nodal points without any explicit meshing connectivity. Therefore, meshfree method can conveniently process the numerical computation inside interested domains with large deformation or inhomogeneity. In this paper, we adopt the idea of meshfree representation into cardiac medical image analysis in order to overcome the difficulties caused by large deformation and inhomogeneous materials of the heart. In our implementation, as element-free Galerkin method can efficiently build a meshfree representation using its shape function with moving least square fitting, we apply this meshfree method to handle large deformation or inhomogeneity for solving cardiac segmentation and motion tracking problems. We evaluate the performance of meshfree representation on a synthetic heart data and an in-vivo cardiac MRI image sequence. Results showed that the error of our framework against the ground truth was 0.1189 ± 0.0672 while the error of the traditional FEM was 0.1793 ± 0.1166. The proposed framework has minimal consistency constraints, handling large deformation and material discontinuities are simple and efficient, and it provides a way to avoid the complicated meshing procedures while preserving the accuracy with a relatively small number of nodes.

Real-time bone sawing interaction in orthopedic surgical simulation based on the volumetric object

Bone sawing is widely used for mandibular angle reduction. In this paper, we develop a surgical simulator for mandibular angle reduction with real-time collision detection, bone reconstruction and force haptic. A volume-based model was organized following the CT or MRI image sequence arrangement. The surgical instrument was simplified into two triangles in geometric model. Then, a new volume-based collision detection method was used to meet the real-time requirements of the simulator. Currently, most of the bone sawing operations regarded the swept surface as the real cut surface of bone. Due to the high-speed reciprocating of the bone saw operation, we innovatively used Marching Cubes Method for the real-time reconstruction of the bone internal sawing part and provided the users with a fine cutting surface. In addition, to obtain a well virtual effect, a simplified bone removal and reconstruction method is carried out to implement the real-time topological changing of the mandibular surface. This paper presents a mechanistic model for prediction of the force during bone sawing, and the simulated force is similar to the measured force in real surgery. Eventually, we realized the high quality visual rendering and tactile rendering, the refresh rate of the force reaches 1000 Hz, and visual refresh frequency up to 30 Hz. To validate the effectiveness of the system, some experiments of simulator evaluation based on the patient-specific data was constructed. Results shown that the virtual orthopedic surgical simulation system can provide inexperienced interns and students with a low-cost, repeatable surgical training platform.

Microstructural integrity of white matter tracts amongst older fallers: A DTI study.

ObjectivesThis study assesses the whole brain microstructural integrity of white matter tracts (WMT) among older individuals with a history of falls compared to non-fallers.Methods85 participants (43 fallers, 42 non-fallers) were evaluated with conventional MRI and diffusion tensor imaging (DTI) sequences of the brain. DTI metrics were obtained from selected WMT using tract-based spatial statistics (TBSS) method. This was followed by binary logistic regression to investigate the clinical variables that could act as confounding elements on the outcomes. The TBSS analysis was then repeated, but this time including all significant predictor variables from the regression analysis as TBSS covariates.ResultsThe mean diffusivity (MD) and axial diffusivity (AD) and to a lesser extent radial diffusivity (RD) values of the projection fibers and commissural bundles were significantly different in fallers (p < 0.05) compared to non-fallers. However, the final logistic regression model obtained showed that only functional reach, white matter lesion volume, hypertension and orthostatic hypotension demonstrated statistical significant differences between fallers and non-fallers. No significant differences were found in the DTI metrics when taking into account age and the four variables as covariates in the repeated analysis.ConclusionThis DTI study of 85 subjects, do not support DTI metrics as a singular factor that contributes independently to the fall outcomes. Other clinical and imaging factors have to be taken into account.

Aneurysms in neurofibromatosis type 2: Evidence for vasculopathy?

There have been anecdotal reports of vasculopathy associated with Neurofibromatosis Type 2 (NF2). Given the increasing use of bevacizumab, a vascular endothelial growth factor inhibitor which results in an increased risk of bleeding, it is important to ascertain if there is a predisposition to vascular abnormalities in NF2. In our unit NF2 patients undergo annual MRI brain and internal auditory meatus imaging. We noted incidental intracranial aneurysms in some patients and sought to determine the prevalence of intracranial aneurysms in our cohort of NF2 patients. We conducted a retrospective audit of the MRI images of 104 NF2 patients from 2014 to 2016. Axial T2 brain MRI images were assessed for vascular abnormalities by two neuroradiologists blinded to patient's clinical details. Intracranial aneurysms were detected in four patients and an aneurysm clip related to previous surgery was noted in one additional patient. Using standard MRI imaging sequences alone we provide evidence of intracranial aneurysms in 4.4% of our cohort. This compares with an estimated overall prevalence of 3% in the general population. We discuss these findings as well as other evidence for a vasculopathy associated with NF2.

Percutaneous Balloon Kyphoplasty in Treatment of Painful Osteoporotic Occult Vertebral Fracture: A Retrospective Study of 89 Cases.

BackgroundThe definition of a vertebral fracture is usually based on the presence of a deformation of the vertebral body and this can be misleading in the presence of a fracture without radiologic collapse with the definition of occult osteoporotic vertebral fractures (OOVFs). STIR sequence of MRI images showing hyperintensity signal was the most confirmative screening examination used to determine the presence of painful OOVFs. To date, clinical management of OOVFs has been rarely discussed.Material/MethodsBetween 2011 and 2013, 89 patients suffering from painful OOVFs underwent 142 percutaneous balloon kyphoplasty (PKP) procedures. Outcome data (mean variation of anterior and middle vertebral body height, visual analog scale [VAS] scores, Oswestry Disability Index [ODI] scores, and SF-36 scores) were recorded preoperatively, postoperatively, and at 1 month, 6 months, and 2 year after treatment, to evaluate the results.ResultsWe successfully treated 89 patients (142 vertebral bodies) with PKP. Cement leakages were observed in 12 (8.45%) treated vertebral bodies and there were 5 new adjacent vertebral fractures during the follow-up period. The mean variation of anterior and middle vertebral body height changed from 96.5±3.4% preoperatively to 97.2±2.5% postoperatively (p>0.05) and from 96.3±2.8% preoperatively to 97.9±3.1% postoperatively (p>0.05), respectively. The mean VAS scores were reduced significantly from pre-surgery to post-surgery (8.3±1.2 to 2.9±0.7; p<0.05), as was the ODI score (76.4±12.5 to 26.7±5.6; p<0.05). The SF-36 scores, including Bodily Pain (BF), Vitality (VT), Physical Function (PF), and Social Functioning (SF), all showed notable improvement (P<0.05). These variations were maintained during the 2-year follow-up period.ConclusionsPKP is a safe and effective method in the treatment of painful OOVFs.

Evaluation of Tissue Repair Using MRI Imaging of Human Intervertebral Discs Cultured in a Bioreactor

Introduction Low back pain is a major problem world-wide, affecting the quality of life for millions of people. Low back pain also has a tremendous impact on direct and indirect global healthcare costs. Intervertebral disc (IVD) degeneration has been strongly associated with low back pain. Long-term organ culture of human IVDs is essential to study IVD degeneration and repair. Using an ex vivo approach, the relationship between mechanobiology, disc matrix composition and metabolism can be better understood in the context of degenerative disease. We have developed a bioreactor where intact human discs can be cultured in a controlled dynamically loaded environment. Here, we aimed to determine the most suitable loading parameters for human discs culture by assessing IVD tissue integrity and cell viability under low, medium and high magnitude cyclic load. Furthermore, we investigated the suitability of this model toward cell supplementation strategies for tissue repair and developed a novel, single disc MRI imaging sequence aimed at direct visualization of tissue repair. Materials and Methods Human IVDs were isolated from lumbar spine segments as previously described. Spines were obtained with consent through the Transplant Quebec Organ Donation Program from individuals who had undergone sustained brain death. Discs were cultured under 3 different loading schemes to mimic a sedentary lifestyle: low 0.1–0.3, medium 0.1–0.6 and high 0.1–1.2 MPa loads. Cell viability and matrix stability was assessed following 10 days of loading. Feasibility of cell/hydrogel implantation was determined over 14 days of medium dynamic loading. To determine whether isolated discs could be imaged by MRI, extracted individual discs were visualized for T1 and T2 signals using a novel sequence using a small animal Bruker 7.5 Tesla MRI. Results Cell viability was maintained at greater than 80% throughout the discs at low and medium loads. Viability dropped to ~60–70% throughout the discs under high loads. Proteoglycan content remained stable in all loading protocols (~50 μg sGAG/mg tissue), as did CHAD and newly synthesized collagen II protein. To test for feasibility of cell therapies in the bioreactors, NP cells combined with a hydrogel were injected into discs and cultured under medium load. 14 days after dynamic culture, the injected cells were mainly localized to the NP region with greater than 90% viability. The small animal MRI was able to obtain well-defined images of isolated discs, with details of tissue integrity and proteoglycan content. Conclusion Our ex vivo model of dynamic human IVD culture can be used as a platform on which to study mechanisms of degeneration as well as for novel avenues aimed at biological repair using bioactive substances or cell based therapies. Cells and bioactive substances can be administered within hydrogels thereby enhancing the reparative properties. Furthermore, it is feasible to assess repair potential of the therapies by comparing MRI scans pre- and post-therapy.

Induction of Gradual Changes in Blood Oxygen Levels in Post Lumpectomy Breast Tissue With Breath Holding: Results of a Pilot Study

Our pilot study investigates whether changes in breast tissue oxygenation, as measured by BOLD MRI contrast, occur with breath holding schedules typically utilized during adjuvant left breast radiation therapy. Ten women status post lumpectomy for breast cancer and undergoing treatment planning for whole breast radiation therapy were enrolled. Each subject underwent an imaging session on a 1.5T GE MRI, immobilized in the prone position on a custom board with a 4 channel breast coil. BOLD contrast MRI imaging was performed using two MRI sequences: T2* based Gradient Echo EPI (TR/TE = 500/41ms, flip angle = 60°) and T2 based Single Shot Fast Spin Echo (SSFSE) (TR/TE = 3000/60ms). For each imaging sequence 1-3 planes of the breast were imaged continuously. After a 1 minute background measurement the subject was asked to hold their breath at inspiration for 20-40 seconds, with 3-5 breath holds total per imaging sequence. We quantified changes in oxygenation as the correlation between the breath holding signal and per-pixel intensity changes from each MRI image sequence. We also investigated the rate of oxygenation response to breath holding using various hemodynamic functions convolved with the breath hold schedule. Statistical significance for BOLD contrast was set at p<0.001. On T2* sequences, all subjects had mixed BOLD contrast signal with areas of increasing and decreasing oxygenation occurring in localized adjacent areas. On T2 sequences, three subjects had consistent oxygen decreases throughout the breast and three subjects had consistent oxygen increases throughout the breast. Compared to a fast hemodynamic function (5s), a slow function (180s) showed increased BOLD contrast within the breast; suggesting that breast oxygenation changes are generally slow hemodynamic effects and are additive over multiple breath holds. We observed correlation between breath holding and blood oxygenation as quantified by BOLD contrast MRI for 6/10 whole breast radiation therapy candidates; however the pattern and magnitude varied considerably between subjects. Changes in breast oxygenation appear to occur slowly and are additive over multiple breath holds. Further study in a larger sample is needed to better understand the effect of breath hold technique on breast tissue oxygenation.

Application of diffusion tensor imaging in AIDS patients with brain opportunistic diseases: A comparative study of tuberculosis and toxoplasmosis

ObjectiveThis paper aims to discuss the diagnostic value of quantitative DTI on AIDS patients with brain tuberculosis or toxoplasmosis. Materials and methods22 subjects (12 with brain tuberculosis and 10 with toxoplasmosis) were recruited, who underwent routine MRI, T1WI-CE and DTI imaging sequence. The morphological characteristics of lesions were observed, and FA and ADC values of the solid areas, edematous areas and the contralateral normal areas of the lesions were calculated. Results were compared by one-way ANOVA and independent sample t-test. The TB diagnosis efficiency of these two values was analyzed by ROC curve. ResultsADC and FA values were detected with significant differences among the three regions between subjects with brain tuberculosis and subjects with toxoplasmosis (P < 0.05). Statistically significant difference was recorded between solid and edematous areas and contralateral areas in ADC and FA values (P < 0.05). And so was between the solid areas and edema areas in either group. Moreover, the FA values of the solid areas between two groups also presented statistically significant difference (P < 0.01). ROC curve of TB showed the AUC of FA value was larger than that of ADC value (0.914 vs. 0.715, respectively, P < 0.05). DTT imaging showed infiltrative changes of white matter fibers in the lesion areas. ConclusionsQuantitative DTI is valuable for diagnosis and differential diagnosis of patients with AIDS-associated infections, and also could provide references for clinical physicians for proper medications. The quantitative FA value could help better reveal different changes of microstructural integrity between different opportunistic infections.

Longitudinal cortex reorganization and white matter tracts structural changes analysis in relapsing-remitting multiple sclerosis patients with hand palsy

Motor disorders are a frequent syndrome in multiple sclerosis (MS), leading to severe disability, possibly associated with inefficiency of adaptive mechanisms, probably because of widespread structural changes. Hand palsy with fine motor skills damage influences greatly on quality of life, because hand function plays an important role in everyday activities and working practices. Thus the aim of the study was to investigate functional and structural features of hand palsy in homogenous sample of MS patients during the relapse and in three months. Data were acquired from 25 relapsing-remitting MS patients during relapse also characterized by unilateral light hand palsy, and in three months. 12 age-matched healthy controls entered the control group. All patients underwent neurologica examination, including nine-hole peg test and dynamometry, and magnetic resonance imaging of cervical spine and brain, including functional MRI and diffusion tensor imaging (DTI) sequences. All patients had lesions in spinal cord on cervical spine MRI. fMRI data analysis during relapse showed differently directed activation changes and allowed to divide all patients in two subgroups. These subgroups differed from each other and control group by deep sensitivity and DTI values. In three months patients in the first subgroup had less complete fine motor skills recovery, which was accompanied also by preservation of activation changes and deep sensitivity asymmetry in comparison with the second subgroup. Received data allow us to assume that clinically similar palsy, caused by spinal cord lesion, could be characterized by greater or lesser sensation impairment contribution. In three months heterogeneous structural and functional changes were observed, depending, possibly, on initially different pathologic mechanisms. Revealed differences should be taken into consideration while rehabilitation planning.

Lossless Compression Method for Medical Image Sequences Using Super-Spatial Structure Prediction and Inter-frame Coding

Space research organizations, hospitals and military air surveillance activities, among others, produce a huge amount of data in the form of images hence a large storage space is required to record this information. In hospitals, data produced during medical examination is in the form of a sequence of images and are very much correlated; because these images have great importance, some kind of lossless image compression technique is needed. Moreover, these images are often required to be transmitted over the network. Since the availability of storage and bandwidth is limited, a compression technique is required to reduce the number of bits to store these images and take less time to transmit them over the network. For this purpose, there are many state-of the-art lossless image compression algorithms like CALIC, LOCO-I, JPEG-LS, JPEG20000; Nevertheless, these compression algorithms take only a single file to compress and cannot exploit the correlation among the sequence frames of MRI or CE images. To exploit the correlation, a new algorithm is proposed in this paper. The primary goals of the proposed compression method are to minimize the memory resource during storage of compressed data as well as minimize the bandwidth requirement during transmission of compressed data. For achieving these goals, the proposed compression method combines the single image compression technique called super spatial structure prediction with inter-frame coding to acquire grater compression ratio. An efficient compression method requires elimination of redundancy of data during compression; therefore, for elimination of redundancy of data, initially, the super spatial structure prediction algorithm is applied with the fast block matching approach and later Huffman coding is applied for reducing the number of bits required for transmitting and storing single pixel value. Also, to speed up the block-matching process during motion estimation, the proposed method compares those blocks that have identical sum and leave the others; therefore, the time taken by the block-matching process is reduced by minimizing the unnecessary overhead during the blockmatching process. Thus, in the proposed fast lossless compression method for medical image sequences, the twostage redundant data elimination process ultimately reduces the memory resource required for storing and transmission. The method is tested on the sequences of MRI and CE images and produces an improved compression rate.

P2‐227: Cross‐vendor implementation and test‐retest analysis of ADNI2 functional MRI (fMRI) and diffusion tensor imaging (DTI) sequences for multicenter clinical trials in Alzheimer's disease

Introduction Strong evidence of neurobiological effects in clinical trials could facilitate the development of new treatments for Alzheimer’s disease. It is expected that cohorts of ~100 prodromal subjects per arm are required to obtain significant results with both vMRI and more recently developed methods such as Diffusion Tensor Imaging (DTI) and resting state functional Magnetic Resonance Imaging (rs-fMRI). For time-efficient trial execution, multi-center studies are required to provide rapid enrollment, however the collection of robust data across different scanner types and is essential. The second phase of the Alzheimer’s Disease Neuroimaging Initiative (ADNI-2) has established 3T DTI and rs-fMRI sequence parameters for GE and Philips systems only, respectively. Our objective was to implement these sequences on Philips, Siemens, and GE scanners and to evaluate their consistency prior to their use in a multi-center clinical trial.

TH-E-BRA-09: Radiation Induced Current Effects on MR Images from an Integrated Linac-MR System

Purpose: During the real-time MR image acquisition of an integrated linac/MRI system, the MRI's RF coils is exposed to pulsed radiation resulting in radiation induced currents (RIC). This work will: (a) visualize the RIC signal as artefacts in k-space and determine its effect on MRI's signal-to-noise ratio (SNR), (b) examine the effects of linac repetition rate (MU/minute) and MRI imaging sequence parameter ‘TR’ on the RIC artefact, (c) use post processing methods to remove the unwanted RIC signal from the MR images. Methods: A small test phantom was imaged with no radiation first. Phantom imaging was then repeated concurrently with linac producing radiation at various repetition rates in two scenarios: (1) the radiation beam was incident on the RF coil unobstructed and (2) a lead block attenuated the radiation beam before reaching the RF coil. Scenario (1) was repeated by obtaining images for several values of TR. Finally, a post-processing algorithm was applied to the corrupted MR k-space data to remove the RIC artefact. Results: The RIC artefact presented as near vertical lines in k-space data for integer ratios of TR to linac pulsing period (rate =180 Hz). For non-integer ratios, the artefact lost its regular pattern and became random in appearance. The RIC artefact disappeared from the k-space data when the linac's radiation was blocked. The image SNR decreased with increasing linac repetition rate. The post-processing method was successful in restoring a significant fraction of the lost image SNR. Conclusions: Signal spikes observed in the k-space data are confirmed to result from RIC. The SNR reduction in MRI images, due to the RIC, is directly related to the linac repetition rate. The artefact's appearance depends on the relationship between linac pulse repetition rate and image sequence timing. Our post-processing algorithm allows the recovery of the lost image SNR. The financial support is provided by the Canadian Institute of Health Research operating grant # MOP 93752.

Thalamic astasia from isolated centromedian thalamic infarction

In thalamic astasia a unilateral thalamic lesion causes postural instability or retropulsion or lateropulsion.1 In previous reports, the responsible lesions have been localized in the posterolateral thalamic area. In contrast to patients with pontomesencephalic lesions, patients with thalamic astasia did not exhibit the clinical signs of ocular tilt reaction.2 Furthermore, the assessment of static graviceptive function by means of the subjective visual vertical (SVV) revealed ipsiversive as well as contraversive deviations of the SVV in these patients.2 We describe a patient with thalamic astasia due to a highly selective unilateral centromedian thalamic lesion. An 82-year-old man with acute onset of astasia with body lateropulsion to the right was admitted to our hospital. Neurologic examination was otherwise normal. MRI disclosed an acute selective ischemic lesion in the left centromedian thalamus (figure). No further brain lesions were detected. An experienced neuroradiologist localized the exact anatomic lesion site using sections from a stereotactic atlas of the human thalamus.3 Figure Cerebral MRI and schematic horizontal thalamic section Axial diffusion-weighted imaging sequence of cerebral MRI shows a small hyperintense lesion with 5-mm diameter in the centromedian part of the left thalamus (left). The correlating lesion site is labeled in …

Plasma glial fibrillary acidic protein levels in children with sickle cell disease

To determine if glial fibrillary acidic protein (GFAP) is associated with brain injury in children with sickle cell disease (SCD), we measured plasma GFAP among cross-sectional groups of unselected children with SCD, subsets of children with SCD and normal brain MRI or MRI evidence of cerebral infarct, healthy pediatric controls, and adults with brain injury. Children with SCD had higher plasma GFAP than healthy pediatric controls (mean concentrations 0.14 ± 0.37 vs. 0.07 ± 0.08 ng/mL; P 5 0.003); also, 16.0% (16/100) of children with SCD and cerebral infarct had GFAP elevations above the 95th percentile of healthy pediatric controls (P 5 0.04). Although not statistically significant, children with SCD and cerebral infarct had more elevated GFAP levels than with SCD and no infarct (16/100, 16.0% vs. 14/168, 8.3%; P 5 0.07). Children with SCD and acute brain ischemia had a higher proportion of elevated GFAP than SCD children with normal MRI (3/6, 50% vs.8.3%; P 5 0.01). GFAP was associated with elevated systolic blood pressure in the preceding year and correlated positively with white blood cell count and negatively with age and performance IQ. Plasma GFAP is elevated among children with SCD and may be associated with subclinical brain injury.

A Lossless Compression Method for Medical Image Sequences Using JPEG-LS and Interframe Coding

Hospitals and medical centers produce an enormous amount of digital medical images every day, especially in the form of image sequences, which requires considerable storage space. One solution could be the application of lossless compression. Among available methods, JPEG-LS has excellent coding performance. However, it only compresses a single picture with intracoding and does not utilize the interframe correlation among pictures. Therefore, this paper proposes a method that combines the JPEG-LS and an interframe coding with motion vectors to enhance the compression performance of using JPEG-LS alone. Since the interframe correlation between two adjacent images in a medical image sequence is usually not as high as that in a general video image sequence, the interframe coding is activated only when the interframe correlation is high enough. With six capsule endoscope image sequences under test, the proposed method achieves average compression gains of 13.3% and 26.3% over the methods of using JPEG-LS and JPEG2000 alone, respectively. Similarly, for an MRI image sequence, coding gains of 77.5% and 86.5% are correspondingly obtained.

A Deformable Object Tracking Algorithm Based on the Boundary Element Method that is Robust to Occlusions and Spurious Edges

The manipulation of deformable objects is an important problem in robotics and arises in many applications including biomanipulation, microassembly, and robotic surgery. For some applications, the robotic manipulator itself may be deformable. Vision-based deformable object tracking can provide feedback for these applications. Computer vision is a logical sensing choice for tracking deformable objects because the large amount of data that is collected by a vision system allows many points within the deformable object to be tracked simultaneously. This article introduces a template based deformable object tracking algorithm, based on the boundary element method, that is able to track a wide range of deformable objects. The robustness of this algorithm to occlusions and to spurious edges in the source image is also demonstrated. A robust error measure is used to handle the problem of occlusion and an improved edge detector based on the Canny edge operator is used to suppress spurious edges. This article concludes by quantifying the performance increase provided by the robust error measure and the robust edge detector. The performance of the algorithm is also demonstrated through the tracking of a sequence of cardiac MRI images.

Segmentation of microscope images of living cells

This paper describes a segmentation method combining a texture based technique with a contour based method. The technique is designed to enable the study of cell behaviour over time by segmenting brightfield microscope image sequences. The technique was tested on artificial images, based on images of living cells and on real sequences acquired from microscope observations of neutrophils and lymphocytes as well as on a sequence of MRI images. The results of the segmentation are compared with the results of the watershed and snake segmentation methods. The results show that the method is both effective and practical.

In-vivo visualisation of the anatomical structures related to the acupuncture points Dai mai and Shen mai by MRI: A single-case pilot study

BackgroundThe concept of acupuncture point localisation in Traditional Chinese Medicine (TCM) is based on millenary practical experience. Modern imaging methods such as PET, MRI and SPECT have been used primary for the investigation of the mechanisms of action of acupuncture. In this pilot single-case study we have evaluated the technical possibilities for in-vivo imaging of the anatomical relations of acupuncture points using state of the art MRI.MethodsPreliminary experiments relating to the quality of acupuncture needles under the setting of MRI were done both with stainless steel and gold needles. In a second step, in-vivo imaging was carried out. A licensed acupuncture practitioner (RM) chose two points belonging to the so-called extraordinary vessels. In 2 sequential, separate procedures, he inserted himself gold acupuncture needles using a neutral technique (known as Ping Bu Ping Xie) into the Dai mai and Shen mai points, i.e. gall bladder 26 and bladder 62. Imaging was done on a Siemens Magnetom Avanto MR scanner using a head array and body coil. Mainly T1-weighted imaging sequences, as routinely used for patient exams, were used to obtain multi-slice images.ResultsIn the preliminary experiments only acupuncture needles made of gold showed enough stability in order to be used for further imaging procedures. Using an onion and a banana as an object, further studies showed that the gold needles produced a void defect that corresponds to the tip of the inserted needle, while at the same time an artefactually increased diameter was observed. The in-vivo experiments showed that the Dai mai point was in relation to the abdominal internal oblique muscle. The Shen mai point artefact showed up close to the longus and brevis peroneal tendons at the fibular malleolus. Side effects related to heating or burning were not observed. Improved anatomical recognition was obtained using 3D-volume rendering techniques.ConclusionThrough an adequate choice of acupuncture material (gold needles) as well as of ideal MRI imaging sequences it has been possible to visualize the anatomical characteristics at the acupuncture points Dai mai and Shen mai in-vivo. At the selected sites the needles showed a relation to tendino-fascial and muscular structures. These anatomical structures fit well into the recently described WOMED concept of lateral tension in which these acupuncture points play a regulatory role.