Low Field MRI: A Review of the Literature and Our Experience in Upper Extremity Imaging

Ghazinoor, Shaya; Crues, John V.

doi:10.1016/j.csm.2006.03.001

Cited by 9 publications

(4 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We would like to emphasize that due to the nature of MRI, poorer image quality is inevitable at low fields in almost all cases no matter what acquisition and reconstruction techniques are used. But as already been illustrated here and shown in several other low field studies [ 4 , 28 – 33 ], worse image quality does not necessarily lead to less diagnostic value. With that in mind, selecting appropriate evaluation criteria becomes very important when comparing the results at different field strengths.…”

Section: Discussionsupporting

confidence: 73%

Minimum Field Strength Simulator for Proton Density Weighted MRI

Chen

Nayak

2016

PLoS ONE

View full text Add to dashboard Cite

ObjectiveTo develop and evaluate a framework for simulating low-field proton-density weighted MRI acquisitions based on high-field acquisitions, which could be used to predict the minimum B0 field strength requirements for MRI techniques. This framework would be particularly useful in the evaluation of de-noising and constrained reconstruction techniques.Materials and MethodsGiven MRI raw data, lower field MRI acquisitions can be simulated based on the signal and noise scaling with field strength. Certain assumptions are imposed for the simulation and their validity is discussed. A validation experiment was performed using a standard resolution phantom imaged at 0.35 T, 1.5 T, 3 T, and 7 T. This framework was then applied to two sample proton-density weighted MRI applications that demonstrated estimation of minimum field strength requirements: real-time upper airway imaging and liver proton-density fat fraction measurement.ResultsThe phantom experiment showed good agreement between simulated and measured images. The SNR difference between simulated and measured was ≤ 8% for the 1.5T, 3T, and 7T cases which utilized scanners with the same geometry and from the same vendor. The measured SNR at 0.35T was 1.8- to 2.5-fold less than predicted likely due to unaccounted differences in the RF receive chain. The predicted minimum field strength requirements for the two sample applications were 0.2 T and 0.3 T, respectively.ConclusionsUnder certain assumptions, low-field MRI acquisitions can be simulated from high-field MRI data. This enables prediction of the minimum field strength requirements for a broad range of MRI techniques.

show abstract

Section: Discussionsupporting

confidence: 73%

Minimum Field Strength Simulator for Proton Density Weighted MRI

Chen

Nayak

2016

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…In such cases, the patient does not have to experience severe discomfort from claustrophobia in the whole-body systems. A review of commercial extremity LF MRI scanners is given by [30]. Hayashi et al [31] and Konar and Lang [32] have made compelling arguments for the use of low field MR scanners.…”

Section: Motivation For Use Of Lf Mrimentioning

confidence: 99%

Approaches in cooling of resistive coil-based low-field Magnetic Resonance Imaging (MRI) systems for application in low resource settings

2021

View full text Add to dashboard Cite

Magnetic Resonance Imaging (MRI), a non-invasive method for the diagnosis of diverse health conditions has experienced growing popularity over other imaging modalities like ultrasound and Computer Tomography. Initially, proof-of-concept and earlier MRI systems were based on resistive and permanent magnet technology. However, superconducting magnets have long held monopoly of the market for MRI systems with their high-field (HF) strength capability, although they present high construction, installation, and siting requirements. Such stringent prerequisites restrict their availability and use in low-middle income countries. Resistive coil-based magnet, albeit low-field (LF) in capacity, represent a plausible boost for the availability and use of MRI systems in resource constrained settings. These systems are characterized by low costs coupled with substantial image quality for diagnosis of some conditions such as hydrocephalus common is such regions. However, the nature of resistive coils causes them to heat up during operation, thus necessitating a dedicated cooling system to improve image quality and enhance system longevity. This paper explores a range of cooling methods as have been applied to resistive magnets, citing their pros and cons and areas for improvement.

show abstract

“…In contrast, high-field scanners have superior image quality because of higher signal-to-noise ratio (SNR), contrast, and resolution. 11 , 12 , 21 , 27 , 34 , 35 It is possible for low-field scanners to improve image quality by increasing scan duration, although doing so also increases the chance of motion artifacts. 2 , 11 , 12 , 21 , 35 While low-field MRI images may not be able to rival the quality of those produced using high-field scanners, it is important to consider whether or not they can provide comparable diagnosis levels to justify their logistical benefits.…”

mentioning

confidence: 99%

Analysis of Low-Field Magnetic Resonance Imaging Scanners for Evaluation of Knee Pathology Based on Arthroscopy

Lee

Davis

McGroder

et al. 2013

Orthopaedic Journal of Sports Medicine

View full text Add to dashboard Cite

Background:In recent years, few studies have evaluated low-field magnetic resonance imaging (MRI) diagnoses compared with intraoperative findings of the knee.Purpose:To determine the accuracy and sensitivity of low-field MRI scanners in diagnosing pathology of the menisci, cruciate ligaments, and osteochondral surfaces.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:MRI examinations without intra-articular contrast were performed on 379 patients for knee pathologies over a 4-year period. The MRI examinations were done using a 0.2-tesla scanner utilizing a dedicated knee coil and read by 1 of 3 board-certified, musculoskeletal fellowship–trained radiologists. Within a mean time of 50 days after MRI, all patients underwent knee arthroscopy performed by 1 of 2 sports fellowship–trained orthopaedic surgeons. Operative notes from the knee arthroscopies were then reviewed by a single independent observer, and the intraoperative findings were compared with the MRI reports.Results:For medial meniscus tears, the sensitivity, specificity, positive predictive value, and negative predictive value were 83%, 81%, 89%, and 71%, respectively. For lateral meniscus tears, the values were 51%, 93%, 84%, and 73%, respectively. For anterior cruciate ligament (ACL) tears, the values were 85%, 94%, 69%, and 97%, respectively. For osteochondral lesions, the values were 8%, 99%, 29%, and 94%, respectively. For posterior cruciate ligament (PCL) tears, the specificity and negative predictive value were 99% and 100%, respectively.Conclusion:Low-field MRI was an accurate tool for evaluation of medial meniscus and ACL tears. However, within the study population, it is not as effective in diagnosing lateral meniscus tears and showed a poor ability to detect osteochondral lesions. More information is needed to properly assess its ability to diagnose PCL tears.

show abstract

Low Field MRI: A Review of the Literature and Our Experience in Upper Extremity Imaging

Cited by 9 publications

References 16 publications

Minimum Field Strength Simulator for Proton Density Weighted MRI

Minimum Field Strength Simulator for Proton Density Weighted MRI

Approaches in cooling of resistive coil-based low-field Magnetic Resonance Imaging (MRI) systems for application in low resource settings

Analysis of Low-Field Magnetic Resonance Imaging Scanners for Evaluation of Knee Pathology Based on Arthroscopy

Contact Info

Product

Resources

About