Multiple Magnetic Resonance Imaging Scans Research Articles

Longitudinal Structural MRI Data Prediction in Nondemented and Demented Older Adults via Generative Adversarial Convolutional Network

Alzheimer’s disease (AD) is the most common cause of dementia and threatens the health of millions of people. Early stage diagnosis of AD is critical for improving clinical outcomes and longitudinal magnetic resonance imaging (MRI) data collection can be used to monitor the progress of each patient. However, missing data is a common problem in longitudinal AD studies. The main factors come from subject dropouts and failed scans. This hinders the acquisition of longitudinal sequences that consist of multi-time-point magnetic resonance (MR) images at relatively uniform intervals. In this paper, we present a generative adversarial convolutional network to predict missing structural MRI data. In particular, we include multiple MRI scans as a temporal sequence collected at different times and determine the spatio-temporal relationship between the different scans in the proposed network. We adopt residual bottlenecks in the generator to decrease parameter values and deepen the network. In order to make full use of the longitudinal information, our discriminator classifies not only real MR images from generated MR images, but also fake sequences from real sequences in which the longitudinal MR images for all time points come from the dataset, only the last MR image comes from the generator. Results of our experiment show that our method performs more accurately for the longitudinal structural MRI data prediction of a brain afflicted with AD.

Acquisition repeatability of MRI radiomics features in the head and neck: a dual-3D-sequence multi-scan study

Radiomics has increasingly been investigated as a potential biomarker in quantitative imaging to facilitate personalized diagnosis and treatment of head and neck cancer (HNC), a group of malignancies associated with high heterogeneity. However, the feature reliability of radiomics is a major obstacle to its broad validity and generality in application to the highly heterogeneous head and neck (HN) tissues. In particular, feature repeatability of radiomics in magnetic resonance imaging (MRI) acquisition, which is considered a crucial confounding factor of radiomics feature reliability, is still sparsely investigated. This study prospectively investigated the acquisition repeatability of 93 MRI radiomics features in ten HN tissues of 15 healthy volunteers, aiming for potential magnetic resonance-guided radiotherapy (MRgRT) treatment of HNC. Each subject underwent four MRI acquisitions with MRgRT treatment position and immobilization using two pulse sequences of 3D T1-weighed turbo spin-echo and 3D T2-weighed turbo spin-echo on a 1.5 T MRI simulator. The repeatability of radiomics feature acquisition was evaluated in terms of the intraclass correlation coefficient (ICC), whereas within-subject acquisition variability was evaluated in terms of the coefficient of variation (CV). The results showed that MRI radiomics features exhibited heterogeneous acquisition variability and uncertainty dependent on feature types, tissues, and pulse sequences. Only a small fraction of features showed excellent acquisition repeatability (ICC > 0.9) and low within-subject variability. Multiple MRI scans improved the accuracy and confidence of the identification of reliable features concerning MRI acquisition compared to simple test-retest repeated scans. This study contributes to the literature on the reliability of radiomics features with respect to MRI acquisition and the selection of reliable radiomics features for use in modeling in future HNC MRgRT applications.

Atrial chamber colocalization for multiple 3D imaging techniques in atrial fibrillation

Abstract Introduction There exist many imaging techniques and systems to reproduce atrial chambers in 3D. These technologies include electroanatomical (EA) mapping systems, noninvasive electrocardiographic imaging (ECGI), magnetic resonance imaging (MRI), or computed tomography (CT) scans. In the case of atrial fibrillation (AF), the most employed non-pharmacological treatment is catheter ablation to electrically isolate the pulmonary veins from the rest of the left atrium. Driver mechanisms such as focal or rotational activity have been proposed as possible initiating and maintaining mechanisms of AF. However, correspondence and validation of these sites when several systems are employed in the same patient remains a challenge, as they are mostly manually aligned based on visual inspection. Purpose To develop an automatic 3D alignment algorithm for cardiac 3D meshes to colocalize points between atrial maps generated with multiple EA mapping systems, ECGI, MRI, or CT scans. Methods A total of 25 left atrial meshes from persistent AF patients were exported from an EA mapping system. The total number of vertices for all the meshes was 2545444 points (101817.8±13593.3 points per map). A reference mesh was employed with minor modifications [1]. All meshes were manually segmented into 12 different left atrial regions, see Table for the region names. The method implements a non-rigid variant of the iterative closest point algorithm to transform the atrial mesh onto the reference one, see Figure. The geographical distance between the mean position of the 12 different segmented reference areas and the 12 transformed points was employed as the performance metric. Results The global error for all the fiducial points in all left atrial meshes was 11.57±2.55 mm. The average local errors for the 12 atrial areas are summarized in the Table. The best three aligned areas were the RSPV, atrial septum, and lateral wall. The areas with less alignment accuracy were the LAA, LSPV, and atrial roof. Conclusions The algorithm provides a promising solution to evaluate and validate site-related results from different systems, e.g., rotational activity presence between EA mapping and ECGI systems. The method works automatically for any given chamber anatomy or any number of points. No prior segmentation is needed since the transformation and co-localization are applied to the raw chamber mesh. Further analysis with a larger mesh database is needed. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III and Ministerio de Ciencia, Innovaciόn y Universidades

Improving radiologists’ and orthopedists’ QoE in diagnosing lumbar disk herniation using 3D modeling

<p>This article studies and analyzes the use of 3D models, built from magnetic resonance imaging (MRI) axial scans of the lumbar intervertebral disk, that are needed for the diagnosis of disk herniation. We study the possibility of assisting radiologists and orthopedists and increasing their quality of experience (QoE) during the diagnosis process. The main aim is to build a 3D model for the desired area of interest and ask the specialists to consider the 3D models in the diagnosis process instead of considering multiple axial MRI scans. We further propose an automated framework to diagnose the lumber disk herniation using the constructed 3D models. We evaluate the effectiveness of increasing the specialists QoE by conducting a questionnaire on 14 specialists with different experiences ranging from residents to consultants. We then evaluate the effectiveness of the automated diagnosis framework by training it with a set of 83 cases and then testing it on an unseen test set. The results show that the the use of 3D models increases doctors QoE and the automated framework gets 90% of diagnosis accuracy.</p>

Automated Detection of Multiple Sclerosis Lesions in Normal Appearing White Matter from Brain MRI: A Survey

Multiple Sclerosis is an inoperable disease of the Central Nervous System (CNS) that irritates the myelin sheath by forming lesions. This affects all organs of the CNS; the vital of them is the brain. This disease can be detected by diagnosis like Magnetic Resonance Imaging (MRI). It is a non-invasive diagnostic test that provides detailed images of the soft tissues of the body. Out of the different variations of MRI, MS lesions are predominantly visible in the DTI (Diffusion Tensor Imaging) variant of MRI. DTI gives enhanced visualization of normal-appearing white matter tracts of the organs, hence providing a better image of the MS lesion. In this paper, the latest methodologies regarding the identification of the MS lesions in MRI scans like T2 FLAIR or DTI, using automated techniques like deep learning, computer vision, neural network and many more are surveyed. Furthermore, this paper consists of a proposed model which would focus on correlating the lesions found in DTI scan with the basic MRI scan like T2. It would identify the MS lesion in DTI scan and eventually highlight that lesion position in the T2 image scan. This would help radiologist in a way to effectively handle multiple MRI scans.

Automated Detection of Multiple Sclerosis Lesions in Normal Appearing White Matter from Brain MRI – A Survey

Multiple Sclerosis is an inoperable disease of the Central Nervous System (CNS) that irritates the myelin sheath by forming lesions. This affects all organs of the CNS; the vital of them is the brain. This disease can be detected by diagnosis like Magnetic Resonance Imaging (MRI). It is a non-invasive diagnostic test that provides detailed images of the soft tissues of the body. Out of the different variations of MRI, MS lesions are predominantly visible in the DTI (Diffusion Tensor Imaging) variant of MRI. DTI gives enhanced visualization of normal-appearing white matter tracts of the organs, hence providing a better image of the MS lesion. In this paper, the latest methodologies regarding the identification of the MS lesions in MRI scans like T2 FLAIR or DTI, using automated techniques like deep learning, computer vision, neural network and many more are surveyed. Furthermore, this paper consists of a proposed model which would focus on correlating the lesions found in DTI scan with the basic MRI scan like T2. It would identify the MS lesion in DTI scan and eventually highlight that lesion position in the T2 image scan. This would help radiologist in a way to effectively handle multiple MRI scans.

Multiple magnetic resonance imaging in patients with implanted sacral nerve stimulator.

The aim of this study was to assess possible impacts of multiple magnetic resonance imaging (MRI) scans on the function of InterStim™ sacral neurostimulator systems (SNS; Medtronic Inc.) devices and on patient's safety. Over the course of 17 years, a total of 16 patients required 72 MRI examinations in various parts of the body. Each time an MRI was performed, the implanting urologist evaluated the SNS device function and deactivated the implant before the scan. Patients were monitored continuously during and after the procedure. After the MRI session, the site of the implanted device was examined, and the SNS device was reactivated. None of the patients experienced pain or discomfort during or after the MRI scan. Impedances and stimulation amplitudes were recorded before and after MRI and showed no statistically significant changes regarding implant function. Micturition-time charts after MRI procedures were compared with previous records and showed no deviations either. No negative consequences of multiple MRIs have been observed. This is the first report of patients successfully undergoing multiple MRI scans despite a previously implanted SNS. Sixteen patients underwent more than one MRI scan, with no negative effect on the functional outcome of SNS or negative side effects for the patients.

Cadaveric Study of the Safety and Device Functionality of Magnetically Controlled Growing Rods After Exposure to Magnetic Resonance Imaging

Study DesignCadaveric study. ObjectiveTo establish the safety and efficacy of magnetically controlled growing rods (MCGRs) after magnetic resonance imaging (MRI) exposure. Summary of Background DataMCGRs are new and promising devices for the treatment of early-onset scoliosis (EOS). A significant percentage of EOS patients have concurrent spinal abnormalities that need to be monitored with MRI. There are major concerns of the MRI compatibility of MCGRs because of the reliance of the lengthening mechanism on strongly ferromagnetic actuators. MethodsSix fresh-frozen adult cadaveric torsos were used. After thawing, MRI was performed four times each: baseline, after implantation of T2–T3 thoracic rib hooks and L5–S1 pedicle screws, and twice after MCGR implantation. Dual MCGRs were implanted in varying configurations and connected at each end with cross connectors, creating a closed circuit to maximize MRI-induced heating. Temperature measurements and tissue biopsies were obtained to evaluate thermal injury. MCGRs were tested for changes to structural integrity and functionality. MRI images obtained before and after MCGR implantation were evaluated. ResultsAverage temperatures increased incrementally by 1.1°C, 1.3°C, and 0.5°C after each subsequent scan, consistent with control site temperature increases of 1.1°C, 0.8°C, and 0.4°C. Greatest cumulative temperature change of +3.6°C was observed adjacent to the right-sided actuator, which is below the 6°C threshold cited in literature for clinically detectable thermal injury. Histologic analysis revealed no signs of heat-induced injury. All MCGR actuators continued to function properly according to the manufacturer's specifications and maintained structural integrity. Significant imaging artifacts were observed, with the greatest amount when dual MCGRs were implanted in standard/offset configuration. ConclusionsWe demonstrate minimal MRI-induced temperature change, no observable thermal tissue injury, preservation of MCGR-lengthening functionality, and no structural damage to MCGRs after multiple MRI scans. Expectedly, the ferromagnetic actuators produced substantial MR imaging artifacts. Level of EvidenceLevel V.

Assessment of consistency of multiple magnetic resonance imaging modalities in measurement of gross tumor volume for nasopharyngeal carcinoma

Objective To investigate the consistency of multiple magnetic resonance imaging (MRI) modalities in measurement of gross tumor volume (GTV) for nasopharyngeal carcinoma. Methods A retrospective analysis was performed among 45 patients who were newly diagnosed and pathologically confirmed with nasopharyngeal carcinoma. All patients underwent plain, enhanced, and diffusion-weighted MRI scans. Primary tumor was manually delineated on enhanced axial T1WI, axial T2WI, and apparent diffusion coefficient (ADC) maps. GTV was calculated by the sum of areas. The obtained GTV was divided into T1+ C group, T2WI group, and ADC group. One-way analysis of variance was used to evaluate the differences between the mean values from the three groups. The Bland-Altman method was used to evaluate the consistency of different imaging modalities in GTV measurement using the mean difference between the two groups and 95% distribution of the difference. Results There was no significant difference in mean GTV between the T1+ C group, the T2WI group, and the ADC group (20.8±18.1) vs. (21.5±17.2) vs. (24.4±20.8) cm3(P=0.617). The mean differences and 95% limits of agreement between the T2WI group and the T1+ C group, between the ADC group and the T2WI group, and between the ADC group and the T1+ C group were 0.74, 2.94, and 3.68 cm3 and (-5.97-7.44), (-8.25-13.69), and (-3.34-10.70) cm3, respectively. Conclusions The multiple MRI modalities have poor consistency in measurement of GTV for nasopharyngeal carcinoma. Therefore, they cannot replace each other. Enhanced T1WI combined with T2WI and DWMRI can determine a relatively accurate range of target volume for nasopharyngeal carcinoma. Key words: Multimodality magnetic resonance; Gross tumor volumel; Consistency

Magnetic Resonance Imaging and Pathologic Findings of 26 Cases With Uterine Adenomatoid Tumors

To analyze the magnetic resonance imaging (MRI) features and pathologic findings of uterine adenomatoid tumors (ATs) for improved diagnostic accuracy and facilitating differential diagnosis of the tumors. We investigated retrospectively 26 patients with uterine ATs confirmed by pathology. Before operation, all patients accepted multiple MRI scans, including T1-weighted image (T1WI), T2-weighted image (T2WI), T2WI/spectrally adiabatic inversion recovery, and T1-weighted enhanced imaging. Two radiologists reviewed all the MRI sequences on PACS workstations for all patients to evaluate the location, shape, size, margin, intensity, and enhancement of ATs. All uterine ATs exhibited either single round solid (n = 24) or predominantly cystic (n = 2) masses with either well-defined (n = 23) or ill-defined margin (n = 3). The diameter range of the tumors was 1.0 to 7.0 cm (mean, 3.8 cm). Solid masses were isointensive on T1WI and hypointensive on T2WI with moderate enhancement. The degree of enhancement in solid tumors was either lower than (18/24 [75%]) or equal to (6/24 [25%]) that of the myometrium. Predominantly cystic masses presented as cystic lesions with a little irregular solid nodule inside. The cystic parts were hypointensive on T1WI and hyperintensive on T2WI without enhancement, whereas the solid nodules were isointensive on both T1WI and T2WI with moderate enhancement. A large part of the uterine ATs (69.2% [18/26]) coexisted with other uterine diseases. On pathology, uterine ATs were characterized as gland-like structures with irregular expansion of tubular cavities, which might be correlated with low enhancement of tumors. The tumors were lined with flat or cuboidal mesothelial cells and residue of smooth muscle component, which might contribute to their hypointensive appearance on T2WI. Small solid uterine masses with homogeneous hypointensity on T2WI and lower enhancement or cystic lesions with inner irregular solid nodule may indicate the diagnosis of uterine ATs, and final diagnosis can be determined with pathology.

240 No influence of magnetic resonance imaging scan on male reproductive hormones

ObjectivesTo investigate if magnetic resonance imaging (MRI) influences male reproductive hormones. The use of MRI is increasing around the world and the possible adverse effects on reproductive health of electromagnetic...

No effects of MRI scan on male reproduction hormones

Magnetic resonance imaging (MRI) is increasing around the world and the possible adverse effects on reproductive health of electromagnetic fields (EMFs) in MRI are not previously studied. A prospective randomized balanced cross-over study using a head scan in real MRI with whole-body transmitting coil and sham MRI among 24 healthy male volunteers was conducted. Serum-blood samples of inhibin B, testosterone, prolactine, thyreotropine, luteinizing hormone, follicle stimulating hormone, sex-hormone binding globuline and estradiol were taken before and after the different scans. Neither immediately after, nor after 11 days were there seen any differences in the hormone levels comparing real and sham MRI. The lack of effects of EMF on male reproductive hormones should be reassuring to the public and especially for men examined in MRI. Adverse effects on other endpoints than male reproduction or possible chronic effect of multiple MRI scans have not been investigated in this study.

Magnetic Resonance Imaging Safety of the Floating Mass Transducer

The goals of this study are to observe 1.5-T magnetic resonance imaging (MRI)-related changes to the Vibrant Soundbridge floating mass transducer (FMT) magnetization, function, and position in different coupling modes within the middle ear; changes to middle ear structures; and effects on the transfer function to the inner ear. The MRI safety of implantable hearing devices is important in daily routine clinical care as well as in urgent care. Nine FMTs were repeatedly investigated before and after MRI scanning. Changes in the position of the FMT (round window, incus, and stapes) and in the ossicular chain in temporal bones were estimated by microscopy, microendoscopy, and flat panel angiography. Functional investigations of the FMT in different coupling modes were done using laser Doppler vibrometry. Qualitative demagnetization could be ruled out in all specimens after up to 11 MRI scans. In FMT couplings to the long process of the incus (n = 18), positional changes were found in 5 temporal bones. A disarticulation or exarticulation of the ossicles was not observed. Mean laser Doppler vibrometry measurements showed MRI-related changes in the stapes velocity. In FMT couplings to the round window (n = 23), we observed a fixation-dependent influence of MRI scanning on the FMT position and mean transfer function. The functional integrity of the FMT was not significantly influenced after multiple MRI scans. Positional changes of the FMT within the middle ear are possible, but we observed no structural damage to middle ear structures. Effects on the transfer function are possible.

Development of an equation to predict muscle volume of elbow flexors for men and women with a wide range of age

The present study examined the age-related changes in muscle thickness (MT) and volume (MV) of elbow flexors and developed a prediction equation of the MV based on the MT applicable to men and women with a wide range of age. The MT and MV were determined from a single ultrasonographic image and multiple magnetic resonance imaging scans, respectively, in 72 men and 75 women aged 19-77 year. As a result of examining the age-MT and age-MV relationships by calculation of partial correlation coefficients with the control variable of gender, MV was decreased with aging whereas the corresponding decline in MT was not significant. The subjects were randomly separated into either a validation (38 men and 42 women) or a cross-validation (34 men and 33 women) group, and a multiple regression equation to estimate MV using not only MT but also upper arm length (L), age and gender as independent variables [MV (cm(3)) = 60.8 x MT (cm) + 6.48 x L (cm) - 0.709 x age (year) + 51.4 x gender (0 women, 1 men) - 187.4] was validated and cross-validated. Thus, the prediction equation for MV of elbow flexors newly developed was shown to be applicable to men and women with a wide range of age.

New Velopharyngeal Measurements at Rest and During Speech

To make proper management decisions, it is important to understand the cause of velopharyngeal inadequacy (VPI) in individual patients. Previous studies suggest that abnormal velar and pharyngeal structures as well as their ratios may contribute to VPI after primary palatal repair in some patients. The aim of the current study was to develop a new protocol to evaluate the velopharyngeal (VP) mechanism and the levator veli palatini muscles at rest and during speech production. A secondary goal was to investigate the correlations among VP measurements and craniofacial structures that may predict velopharyngeal motions during speech production. Seventeen healthy adults were scanned with magnetic resonance imaging (MRI) techniques. Multiple MRI scans covered the craniofacial region, the VP mechanism, and the levator veli palatini muscles at rest and during sustained phonations of /a/, /i/, /z/, /m/, and /f/. Measurements of craniofacial and VP structures at rest and during speech productions were obtained using image analysis software. The maximal effective VP ratio, maximal pharyngeal constriction ratio, maximal velar stretch ratio, maximal velar height, and maximal levator shortening ratio were selected to represent the functional properties of the VP mechanism. The following predictors were found to partially explain the variances of corresponding measurements: rest effective VP ratio for the maximal effective VP ratio, maximal pharyngeal constriction for the maximal pharyngeal constriction ratio, and rest and maximal effective VP ratios for the maximal velar stretch. These predicting effects had implications in VP surgery and in understanding VP physiology. This study developed a practical imaging protocol to measure the VP mechanism at rest and during speech productions. New measurements such as the effective VP ratio, pharyngeal constriction ratio, velar stretch ratio, and levator shortening ratio may help to identify the cause of persistent VPI after palatal repair. Implications on the VP surgery were discussed.

Magnetic resonance imaging with gadolinium enhancement in renal failure: a need for caution

A 36-year-old Asian man with von Hippel-Lindau syndrome was referred to the dermatology clinic in January 2005 with stiff fingers and ankles of 3 months' duration. He had undergone bilateral nephrectomy for renal squamous cell carcinoma in 2002 and had started hemodialysis. Multiple cerebellar hemangiomata were resected in 1991, 2001, and 2003, and consequently he underwent multiple magnetic resonance imaging (MRI) scans with gadolinium-based contrast agents whilst on hemodialysis. The serum creatinine level and calculated glomerular filtration rate (GFR) at the time of his first exposure to gadolinium were 584 micromol/L and 13.31 mL/min, respectively. The patient recalled his symptoms worsening dramatically immediately after he had undergone two MRI scans on a day on which he was not dialyzed. On examination, he had thickening and edema on the hands and feet with significant pain and loss of range of movement. Autoantibodies for connective tissue disorders and thrombophilia screen were negative. Histology showed a proliferation of fibroblasts and dendritic cells, thickened collagen bundles, increased elastic fibers, and mucin deposition, consistent with the diagnosis of nephrogenic fibrosing dermopathy (NFD) (Figs 1 and 2). A trial of thalidomide for several months was unhelpful. He received a live, unrelated renal transplant in August 2005 but, despite excellent renal function and early conversion to sirolimus, his symptoms continued to progress. He now has contractures of all the limbs (Figs 3 and 4) and great difficulty with the activities of daily living. He is receiving physiotherapy and being considered for extracorporeal photophoresis therapy.

Time-series analysis of MRI intensity patterns in multiple sclerosis

In progressive neurological disorders, such as multiple sclerosis (MS), magnetic resonance imaging (MRI) follow-up is used to monitor disease activity and progression and to understand the underlying pathogenic mechanisms. This article presents image postprocessing methods and validation for integrating multiple serial MRI scans into a spatiotemporal volume for direct quantitative evaluation of the temporal intensity profiles. This temporal intensity signal and its dynamics have thus far not been exploited in the study of MS pathogenesis and the search for MRI surrogates of disease activity and progression. The integration into a four-dimensional data set comprises stages of tissue classification, followed by spatial and intensity normalization and partial volume filtering. Spatial normalization corrects for variations in head positioning and distortion artifacts via fully automated intensity-based registration algorithms, both rigid and nonrigid. Intensity normalization includes separate stages of correcting intra- and interscan variations based on the prior tissue class segmentation. Different approaches to image registration, partial volume correction, and intensity normalization were validated and compared. Validation included a scan–rescan experiment as well as a natural-history study on MS patients, imaged in weekly to monthly intervals over a 1-year follow-up. Significant error reduction was observed by applying tissue-specific intensity normalization and partial volume filtering. Example temporal profiles within evolving multiple sclerosis lesions are presented. An overall residual signal variance of 1.4% ± 0.5% was observed across multiple subjects and time points, indicating an overall sensitivity of 3% (for axial dual echo images with 3-mm slice thickness) for longitudinal study of signal dynamics from serial brain MRI.

P31Structural reorganization of the brain after perinatal damage – US/MRI review

BackgroundThe aim of this study was to estimate structural reorganization of the brain after perinatal brain damage, diagnosed by ultrasonography (US) in the neonatal period, using magnetic resonance imaging (MRI).MethodsA follow up study was carried out on a cohort of 28 perinatal risk children who were ultrasonographicaly followed during the first 2 years of life. 22 children, who had intraventricular haemorrhage (IVH I and II), were in the investigation group and the other 6, who had continuous normal us findings, were in the control group. Follow up included high resolution 2T magnetic resonance imaging of the brain at 13–16 years. Results MRI normal PV1 CA2 ML3 cases (n = 22) US IVH I (n = 12) 9 0 2 1 IVH II (n = 10) 4 3 1 2 controls (n = 6) 4 2 0 0 PV = periventricular tracks of haemorrhage; CA = cortical atrophy; ML = multiple lesions ConclusionAbnormal MRI scans are more frequently in the cases with IVH II, than in the cases with IVH I. We can conclude that structural reorganization of the brain can repair majority of mild perinatal intraventricular haemorrhage.

Preoperative and postoperative magnetic resonance imaging (MRI) findings of radiculomeningeal arteriovenous malformations: Important role of gravity in the symptoms and MRI

The symptoms of radiculomeningeal arteriovenous malformations (AVMs) are reported to be uniform, which suggests it to be a conus medullaris syndrome, and in fact, the lesions on magnetic resonance imaging (MRI) images usually include the conus medullaris. However, the reason why the conus medullaris is always involved in the lesion has not been discussed. We encountered seven patients with spinal radiculomeningeal AVMs and operated on all of them. We evaluated the preoperative and postoperative MRI findings in these patients. Postoperative MRI was followed ranging from 6-32 months (mean: 21 months) after surgery. All of our patients showed swelling of the spinal cord, including the conus medullaris, on the preoperative magnetic resonance image. Postoperatively, MRI showed that the swelling of the spinal cord had resolved but that it had finally deteriorated into an atrophic condition. In all of five patients who could be followed up using multiple postoperative MRI scans, sequential T2-weighted images showed that the most rostral level of areas with increased signal in the spinal cord moved in a caudal direction with time. This and the fact that the conus medullaris was included in the swelling of the spinal cord regardless of the level of the nidus in all our patients, suggested that gravity played an important role in the etiology of radiculomen-ingeal AVM in these patients.