Implementation Of Magnetic Resonance Imaging Research Articles

Diagnostic Methods for the Prenatal Detection of Cleft Lip and Palate: A Systematic Review.

Background: Accurate prenatal diagnosis of cleft lip and palate is essential to discuss severity prediction, perform appropriate parental counseling, and, at last, establish long-term treatment planning. The aim of this systematic review was to analyze the accuracy of various imaging techniques for the prenatal diagnosis of cleft lip and palate, assess the pregnancy phase for orofacial clefts diagnosis, and study the different cleft types in terms of diagnostic methods, timing, and predictability. Methods: A search of the PubMed, EMBASE, Scopus, and Web of Science databases was conducted to identify potentially relevant studies published until January 2024. The quality of the selected articles was assessed using the Newcastle-Ottawa scale for methodological quality assessment of cohort studies and the QUADAS-2 scale for diagnostic test studies. Results: A total of 18 studies met the eligibility criteria and were included in the review. The findings of this review indicate that the majority of studies showed improved diagnostic accuracy when supplementary techniques, such as 3D ultrasound or magnetic resonance imaging, were added to 2D ultrasound. Conclusions: The implementation of magnetic resonance imaging as a standard procedure could significantly improve the precision of diagnosing cleft lip and palate. Therefore, the diagnostic technique used will play a crucial role in the accuracy of the diagnosis.

Association of Internal and External Motion Based on Cine MR Images Acquired During Real-Time Treatment on MRI–Guided Linear Accelerator for Patients With Lung Cancer

With the recent clinical implementation of magnetic resonance imaging (MRI)-guided linear accelerators, a large number of real-time planar MR images has been acquired during lung cancer treatment as a standard of care. In this study, associations among lung tumor, diaphragm, and external skin movement were studied based on MR cine imaging during the entire duration of each treatment fraction. This retrospective study used 181,798 planar MRI frames acquired over 55 treatment/imaging sessions of 13 patients with lung cancer treated on 2 MRI-guided linear accelerators. From each planar MR image frame, in-house software automatically extracted 9 features: the superior-interior (SI) and posterior-anterior (PA) positions of a lung tumor; the area of the lung (Lung_Area); the posterior (Dia_Post), dome/apex (Dia_Dome), and anterior (Dia_Ant) points of a diaphragmatic curve; the diaphragm curve point (Dia_Max); and the chest (Chest) and belly (Belly) skin points experienced the maximum range of motions. Correlation analyses were performed among the 9 features for every session. Lung tumor motion range and standard deviations were calculated based on positions obtained in cine images and compared with motion ranges obtained from 4-dimensional computed tomography images. In the study, 177,009 frames of images were successfully analyzed. For all patients, correlation coefficients were as follows: 0.91 ± 0.10 between any 2 features among Lung_Area, Dia_Post, Dia_Dome, and Dia_Max; 0.82 ± 0.21 between SI and any feature among Lung_Area, Dia_Post, Dia_Dome, and Dia_Max; 0.75 ± 0.24 between SI and Belly. Six of 13 patients were considered large amplitude motion (patients with lung tumor SI motion standard deviation >5 mm). Furthermore, 92,956 frames of images were analyzed for the 6 large-amplitude motion patients. For this set, correlation coefficients were 0.93 ± 0.07 between any 2 features among Lung_Area, Dia_Post, Dia_Dome, and Dia_Max; 0.94 ± 0.06 between SI and any feature among Lung_Area, Dia_Post, Dia_Dome, and Dia_Max; and 0.90 ± 0.09 between SI and Belly. Both belly and diaphragmatic motions as assessed by cine MRI are highly correlated with large amplitude lung tumor motion in the longitudinal axis.

Outcome After Treatment of Spinal Ependymoma in Children and Adolescents: Long-Term Follow-up of a Single Consecutive Institutional Series of 33 Patients Treated Over Eight Decades

Long-term outcomes for pediatric patients treated for spinal ependymoma are unknown. We performed a retrospective analysis of outcome data from 33 children and young adults (0-22 years) who were operated on for a spinal ependymoma at our institution during the last 8 decades (1938-2019). Nineteen patients are alive, with follow-up period up to 60 years. Twelve of them are tumor-free, and 7 are alive with disease. Fourteen patients are dead, 9 of them due to recurrent and/or progressive disease 1-56 years (median: 11 years) after the initial surgery. Four of the deceased patients were treated before 1948, 3 of them with excellent long-term survival for 62-66 years after the initial surgery. Tumor recurrence was observed in half of the patients, both local at the site of the primary tumor resection as well as widespread intraspinal presentations. Recurrences were observed within months but also occurred after up to 20 years after initial treatment. After the implementation of magnetic resonance imaging in 1987, details of recurrent disease became more easily demonstrated. Repeated resections were performed when the symptomatic spinal disease was in progress (n= 11). Furthermore, 2 patients have intracranial tumor manifestations, 1 of them underwent resection of a suprasellar tumor in 1991. Four deceased patients experienced aggressive extraspinal progressive disease requiring multiple surgeries, including pulmonary metastasis in 1 of them. Pediatric spinal ependymomas can be treated with favorable results and functional outcome may be good even after more than half a century of follow-up. Nevertheless, unexpected and late recurrences may occur, and life-long follow-up is therefore recommended.

The influence of a magnetic field on photon beam radiotherapy in a normal human TK6 lymphoblastoid cell line

BackgroundThe implementation of magnetic resonance imaging (MRI) guided radiotherapy (RT) continues to increase. Very limited in-vitro data on the interaction of ionizing radiation and magnetic fields (MF) have been published. In these experiments we focused on the radiation response in a MF of the TK6 human lymphoblastoid cells which are known to be highly radiosensitive due to efficient radiation-induced apoptosis.MethodsClonogenicity was determined 12–14 days after irradiation with 1–4 Gy 6 MV photons with or without a 1.0 Tesla MF. Furthermore, alterations in cell cycle distribution and rates of radiation induced apoptosis (FACS analysis of cells with sub-G1 DNA content) were analyzed.ResultsClonogenic survival showed an exponential dose-dependence, and the radiation sensitivity parameter (α = 1.57/Gy) was in accordance with earlier reports. Upon comparing the clonogenic survival between the two groups, identical results within error bars were obtained. The survival fractions at 2 Gy were 9% (without MF) and 8.5% (with MF), respectively.ConclusionA 1.0 Tesla MF does not affect the clonogenicity of TK6 cells irradiated with 1–4 Gy 6MV photons. This supports the use of MRI guided RT, however ongoing research on the interaction of MF and radiotherapy is warranted.

Clinical implementation of magnetic resonance imaging guided adaptive radiotherapy for localized prostate cancer.

Background and purposeMagnetic resonance-guided radiation therapy (MRgRT) has recently become available in clinical practice and is expected to expand significantly in coming years. MRgRT offers marker-less continuous imaging during treatment delivery, use of small clinical target volume (CTV) to planning target volume (PTV) margins, and finally the option to perform daily plan re-optimization.Materials and methodsA total of 140 patients (700 fractions) have been treated with MRgRT and online plan adaptation for localized prostate cancer since early 2016. Clinical workflow for MRgRT of prostate cancer consisted of patient selection, simulation on both MR- and computed tomography (CT) scan, inverse intensity-modulated radiotherapy (IMRT) treatment planning and daily plan re-optimization prior to treatment delivery with partial organs at risk (OAR) recontouring within the first 2 cm outside the PTV. For each adapted plan online patient-specific quality assurance (QA) was performed by means of a secondary Monte Carlo 3D dose calculation and gamma analysis comparison. Patient experiences with MRgRT were assessed using a patient-reported outcome questionnaire (PRO-Q) after the last fraction.ResultsIn 97% of fractions, MRgRT was delivered using the online adapted plan. Intrafractional prostate drifts necessitated 2D-corrections during treatment in approximately 20% of fractions. The average duration of an uneventful fraction of MRgRT was 45 min. PRO-Q’s (N = 89) showed that MRgRT was generally well tolerated, with disturbing noise sensations being most commonly reported.ConclusionsMRgRT with daily online plan adaptation constitutes an innovative approach for delivering SBRT for prostate cancer and appears to be feasible, although necessitating extended timeslots and logistical challenges.

Long-term improvement in cardiac magnetic resonance in β-thalassemia major patients treated with deferasirox extends to patients with abnormal baseline cardiac function.

The management of iron overload in thalassemia has changed dramatically since the implementation of magnetic resonance imaging, which allows detection of preclinical iron overload and prevention of clinical complications. This study evaluated the effect of deferasirox (DFX), the newest once-daily oral chelator, on cardiac function, iron overload and cardiovascular events over a longer follow up in a "real world" setting. Longitudinal changes in cardiac magnetic resonance T2*, cardiac function parameters and cardiovascular clinical events were assessed in a cohort of 98 TM patients exposed to DFX for a mean of 6.9 years (range 1.8-11.6 years). No cardiac death or incident heart failure occurred. Cardiac T2* significantly increased (+2.6 ± 11.9 msec; P = 0.035) in the whole population, with a significantly greater increase (+11.6 ± 15.5 msec, P = 0.019) in patients with cardiac iron overload (T2* <20 ms). A significant improvement in left-ventricular ejection fraction (LVEF) (from 50.6 ± 6 to 60.2 ± 5; P = 0.001) was observed in 11 (84.6%) out of 13 patients who normalized cardiac function (LVEF >56%). Arrhythmias were the most frequent cardiac adverse event noted but none led to DFX discontinuation. Our data indicate that DFX is effective in maintaining cardiac iron level in the normal range and in improving cardiac iron overload. No heart failure or cardiac death was reported over this longer observation up to 12 years. For the first time, a DFX-induced improvement in LVEF was observed in a subgroup of patients with abnormal cardiac function at baseline, a preliminary observation which deserves further evaluation.

Technical Note: U-net-generated synthetic CT images for magnetic resonance imaging-only prostate intensity-modulated radiation therapy treatment planning.

Clinical implementation of magnetic resonance imaging (MRI)-only radiotherapy requires a method to derive synthetic CT image (S-CT) for dose calculation. This study investigated the feasibility of building a deep convolutional neural network for MRI-based S-CT generation and evaluated the dosimetric accuracy on prostate IMRT planning. A paired CT and T2-weighted MR images were acquired from each of 51 prostate cancer patients. Fifteen pairs were randomly chosen as tested set and the remaining 36 pairs as training set. The training subjects were augmented by applying artificial deformations and feed to a two-dimensional U-net which contains 23 convolutional layers and 25.29 million trainable parameters. The U-net represents a nonlinear function with input an MR slice and output the corresponding S-CT slice. The mean absolute error (MAE) of Hounsfield unit (HU) between the true CT and S-CT images was used to evaluate the HU estimation accuracy. IMRT plans with dose 79.2Gy prescribed to the PTV were applied using the true CT images. The true CT images then were replaced by the S-CT images and the dose matrices were recalculated on the same plan and compared to the one obtained from the true CT using gamma index analysis and absolute point dose discrepancy. The U-net was trained from scratch in 58.67h using a GP100-GPU. The computation time for generating a new S-CT volume image was 3.84-7.65s. Within body, the (mean±SD) of MAE was (29.96±4.87) HU. The 1%/1mm and 2%/2mm gamma pass rates were over 98.03% and 99.36% respectively. The DVH parameters discrepancy was less than 0.87% and the maximum point dose discrepancy within PTV was less than 1.01% respect to the prescription. The U-net can generate S-CT images from conventional MR image within seconds with high dosimetric accuracy for prostate IMRT plan.

Effect of Lesion Location on Prostate Cancer Detection Rate with Magnetic Resonance Imaging Targeted Biopsy in African Americans

PurposeThe updated Prostate Imaging Reporting and Data System version 2 (PI-RADSTM v2) defines different grading parameters for lesions located in the peripheral zone (PZ) versus the transitional zone (TZ) and has contributed to the implementation of magnetic resonance imaging targeted biopsy (MRI-TB). This study evaluated the efficacy of MRI-TB between African American patients with additional consideration for lesion location on MRI. Materials and MethodsA retrospective review of MRI-TB was performed at a single institution treating a racially diverse population. A single radiology group read the prostate mpMRI and followed PI-RADSTM v2 algorithms to categorize lesions. ResultsA total of 214 lesions from 125 men were included in the analysis, 162 (75.7%) in the PZ and 52 (24.3%) in the TZ. There were 64 lesions from African American patients and 150 from White patients, with location distributed proportionately. The 48 anterior lesions (22.4%) had a higher PI-RADSTM v2 score and trended towards larger size. The overall cancer detection rate (CDR) was 50% and did not differ significantly between prostatic zones (p = 0.5468) or racial groups (p = 0.2294). The cancer upgrade rate (CUR) was 41 percent and also did not differ significantly between prostatic zones (p = 0.5134) or racial groups (p = 0.2365). Anterior lesions had higher CDR (p = 0.0117) and trended towards higher CUR (p = 0.0781). ConclusionsThis study provides evidence that MRI-TB is equally effective with African American and White men and does not preferentially identify prostate cancer in either the PZ or TZ.

Clinical Implementation of Magnetic Resonance Imaging Systems for Simulation and Planning of Pediatric Radiation Therapy

AimTo describe the clinical implementation and optimization of magnetic resonance imaging (MRI) systems installed in a radiation oncology department for dedicated use in radiotherapy (RT) simulation and treatment planning for pediatric patients. MethodsTwo wide-bore MRI systems were installed and commissioned in 2016. Patient setups, coil placements, and scan protocols were developed to image various anatomic sites in children. Patients with brain tumors were routinely imaged using a pair of flexible loop coils and a posterior receiver coil integrated into the patient couch. The integrated posterior coil and the flexible anterior torso coil supported by the coil bridge were used together when imaging the abdomen, pelvis, or spine. A three-dimensional acquisition was most often performed, given the benefit of high-resolution multiplanar reformation as well as elimination of B0-related distortions in the slice selection direction. ResultsWe performed 542 MRI studies (265 for planning and 277 for monitoring on-treatment tumor changes) on pediatric patients in the first year after system installation. Multisequence images of pediatric RT patients with ependymoma, medulloblastoma, craniopharyngioma, rhabdomyosarcoma, or Ewing sarcoma were shown to illustrate the image quality obtainable with optimized planning sequences. ConclusionsMagnetic resonance imaging (MRI) of pediatric patients in their treatment positions with setup devices in place can be performed with coil arrangements that include flexible coils. The resulting image quality is suitable for treatment planning and on-treatment monitoring. We provide optimized site-specific sequence parameters to support the continued improvement of MRI for pediatric RT planning.

Prostate ultrasound: back in business!

The use of grey scale prostate ultrasound decreased after the implementation of magnetic resonance imaging (MRI) for thediagnosis and evaluation of prostate cancer. The new developments, such as multiparametric ultrasound and MRI-ultrasoundfusion technology, renewed the interest for this imaging method in the assessment of prostate cancer. The purpose of this paperwas to review the current role of prostate ultrasound in the setting of these new applications. A thorough reevaluation of theselection criteria of the patients is required to assess which patients would benefit from multiparametric ultrasound, who wouldbenefit from multiparametric MRI or the combination of both to assist prostate biopsy in order to ensure the balance betweenoverdiagnosis and underdiagnosis of prostate cancer.

Penile biometry on prenatal magnetic resonance imaging

In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI. This was a retrospective study of MRI of 194 male fetuses (18-34 weeks' gestation) with normal anatomy or minor abnormalities. On sagittal T2-weighted MRI sequences, we measured penile length from the glans tip to the scrotal edge (outer length) and from the glans tip to the symphyseal border (total length). Descriptive statistics, as well as correlation and regression analysis, were used to evaluate penile length in relation to gestation. T-tests were calculated to compare mean outer/total length on MRI with published ultrasound data. Mean length values, including 95% CIs and percentiles, were defined. Penile length as a function of gestational age was expressed by the following regression equations: outer mean length = - 5.514 + 0.622 × gestational age in weeks; total mean length = - 8.865 + 1.312× gestational age in weeks. The correlation coefficients, r = 0.532 and r = 0.751, respectively, were statistically significant (P < 0.001). Comparison of outer penile length on MRI with published ultrasound penile length data showed no significant differences, while total penile length on MRI was significantly greater than ultrasound penile length (P < 0.001). Our MRI results provide a reference range of fetal penile length, which, in addition to ultrasonography, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on ultrasound, whereas total length is significantly greater.

Superconductivity in Medicine

Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

Magnetic resonance imaging of the elbow

With the current popularity of racket and throwing sports, the number of individuals seeking medical care for elbow pain and dysfunction has increased rapidly. Before the development and implementation of magnetic resonance imaging (MRI), radiologic imaging examinations provided the treating physician limited information to determine the precise etiology of elbow disorders, because they usually involve soft-tissue structures. With MRI, it is now possible to accurately assess the integrity of the ligaments, tendons, and muscles surrounding the elbow, and to detect pathologic changes in these tissues secondary to acute macrotrauma or chronic microtrauma, e.g., overuse injuries. By defining the nature and extent of these abnormalities, the choice of the appropriate therapeutic regimen is facilitated. With MRI, it is also now possible to noninvasively evaluate the natural history of these soft-tissue disorders and to determine the effects of different therapeutic interventions.

Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Magnetic Resonance Imaging of the Shoulder*†

The foundation of successful patient care is an accurate clinical diagnosis. The accomplishment of this goal begins with a complete history and physical examination. If the initial evaluation does not provide the information needed to explain the symptoms, additional diagnostic testing is usually needed. The additional data provided by these tests become useful clinical information only when they are integrated with the patient's history and the results of the physical examination and other ancillary tests. Imaging studies may also be part of the preoperative workup in order to confirm the presence of a pathological condition and to determine its extent. In the past, radiographic imaging studies, such as plain radiography and computed tomography, and radionuclide studies, have played a major role in the diagnostic evaluation of patients who have a musculoskeletal disorder. These studies focused mainly on the detection of osseous abnormalities. With the recent development and implementation of magnetic resonance imaging, it is now possible to evaluate non-invasively the soft-tissue structures of the body, such as muscles, tendons, and ligaments, which are the structures frequently responsible for most of the symptoms in patients who have musculoskeletal dysfunction. The goal of any imaging study is to define accurately the pathomorphological changes in a specific tissue, organ, or part of the body. Whenever possible, objective diagnostic criteria should be employed when the findings of an imaging study are reported. Objective categorization of pathological changes facilitates the interpretation and communication of abnormalities detected on a test, and these same criteria can then be used when follow-up tests are performed to assess the effects of different forms of therapy, such as operative intervention or non-operative rehabilitation. The reproducibility and reliability of all objective diagnostic criteria must be evaluated rigorously in prospective, blinded studies before they are implemented64. Complete assessment of all …

Economic assessment of magnetic resonance imaging for inpatients: is it still too early?

This economic assessment of the implementation of magnetic resonance imaging (MRI) in a French hospital examines data on the diagnostic resources used in neurology and neurosurgery before and after MRI was available. Given a similar patient population and case mix, there was no change in the resources used other than the addition of MRI. So far, MRI appears to be a complement to, and not a substitute for, other imaging techniques used in neuroradiology. The focus of this work is purely economic; its conclusions do not challenge the major scientific contributions of MRI.