MRI Accreditation Research Articles

WE-G-217A-09: Phase Imaging Measurement of Static Magnetic Field Homogeneity.

The ACR MRI accreditation program requires measurement of the magnetic field homogeneity (MFH) in the annual QA. Full implementation of vendor methods can be very time consuming and incorporates techniques not available to clinical physicists. Conversely, many of the less involved techniques proposed tend to be less inaccurate and/or precise. Here, we propose a robust approach to MFH analysis using a simple phase mapping acquisition which is a time efficient compromise. The root mean square (r.m.s.) for MFH measurement is commonly used over multiple slices (∼24). In regions with high SNR, the MR signal can be reasonably assumed Gaussian distributed. Therefore, the standard deviation of phase values in ROI is equivalent to the r.m.s. of those. The standard deviations of phases in x, y and z are assumed uncorrelated. Thus, only axial, sagittal and coronal planes need to be acquired to approximate the MFH as opposed to a full 3D acquisition. To investigate this concept, phase images were acquired on four 1.5T clinical scanners and one 3.0 clinical scanner (MAGNETOM Espree, Siemens Medical Systems, Signa Excite HD 1.5T, and 3.0T GE Healthcare Technologies). The manufacturer phantoms were scanned using two echo times (delta_TE=TE2-TE1<5ms) using a simple 2D gradient echo acquisition to produce phase images. After acquiring phase difference images in three orthogonal planes, the standard deviation was calculated in three circular ROIs (Diameter=10, 20 and 30cm) in each plane, respectively, to estimate the MFH for the effective DSV. The MFH values in five scanners using this method were within vendor specifications for the DSV. Additionally, the measured MFH values compared favorably with vendor planned maintenance records with <0.1 ppm discrepancy. This proposed method may be a reliable and practical for regular MFH measurement in QA programs and providing an independent check of the vendor measurement.

TU‐A‐211‐01: ACR MRI Accreditation: Process and Pitfalls

ACR MRI accreditation was initiated in 1996. Over the years, the accreditation process and requirements have evolved in order to keep pace with the rapidly changing MRI technology. This presentation will briefly review changes that have been initiated in response to the changing technology along with the evolving changes in the responsibilities of the Medical Physicist for providing advice and support for system performance, quality assurance and safety. Specific differences in the accreditation process between conventional general‐purpose MRI systems and specialty (extremity) systems used for anatomical imaging and systems used for breast imaging will be discussed. Additional requirements that have resulted from the Medicare Improvements for Patients and Providers Act (MIPPA), common reasons for accreditation failure and the anticipated changes and updates to the 2004 ACR MRI Quality Control Manual will also be discussed.Learning Objectives:1. Review the responsibilities of the Medical Physicist in the accreditation process2. Discuss the CMS/MIPPA accreditation requirements as of January 1, 2012.3. Review differences in breast and specialty (extremity) system accreditation4. Discuss common reasons for accreditation failure5. Discuss anticipated changes and updates in the ACR MRI Quality Control Manual

SU-E-T-192: Spatial Accuracy Considerations in the Development of a Gamma Knife Quality Assurance Program

Purpose: Spatial accuracy in a Gamma Knife SRStreatment plan is of utmost importance because of the single fraction high doses of ionizing radiation intended to be delivered to small volumes often times at close proximity to critical brain structures. Methods: Leksell‐Gamma Knife head frames and associated fiducial marker box attached to a phantom, as well as the MRI scanner were studied in this regard. Three phantoms with known geometrical accuracy were scanned. These included the ACR MRI accreditation phantom, GEMRI standard calibration phantom, and a specifically designed MRI phantom. The latter phantom consists of known size and positional coordinates of structures including a cone, cube, cylinder, and sphere. Observed measurements were made using a GE 1.5 tesla MRI scanner. Scanning was done following our standard protocol, i.e. T1 imaging, 512×512 pixels, 28×28 cm fov, and 1.5 mm slice thickness with no gap. All data was analyzed after being dicom transmitted to our Gamma Knife Treatment Planning computer. Results: We will show that over many applications of the head frame to patients, warping of the head frame can and does occur. Fiducial marker boxes are unlikely to warp or change the parameters of the copper sulfite tracks. The MRI scanner remains spatially accurate as long as a gradient field test is done routinely and attention is closely paid to the head coil and its associated small field gradient. This is generally accomplished during routine PMI by the manufacturer. Conclusions: Head frame alignment parameters dictate where the fiducial markers are actually found. If the fiducial marker parameters measured do not agree with the known position of the fiducial markers as stored in the treatment planning computer errors occur in the “Leksell” coordinate frame space. Clues will be provided indicating that the head frame has warped out of allowed tolerances.

SU‐E‐J‐75: Clinical Commissioning and Quality Assurance Procedures for a Wide Bore MRI Unit Configured for Radiation Therapy Planning

Purpose: To develop a comprehensive protocol for the acceptance testing and clinical commissioning a wide bore (70cm) MRI‐Simulator for radiotherapy localization and planning.Methods: A GE 1.5T Optima 450W MR scanner was installed in our department in 2010. Standards derived from the ACR MRI Accreditation Program were used as reference for acceptance testing and commissioning. Commercially available phantoms were used to characterize magnetic field homogeneity, image intensity uniformity, high contrast spatial resolution, slice thickness, position accuracy and geometric accuracy. For 2D SE, GRE and 3D CUBE imaging sequences, in plane and through plane distortion and distortion correction accuracy with and without the GradWarp distortion algorithm provided the software was assessed. The test was performed using multi ROI at different locations off center with multiple slices using the Magphan® phantom. Couch position, couch load and laser system accuracy were also assessed. Daily QA procedures were developed for SNR, RF, isocenter position and the gradient linearity. Parameters derived from commissioning were utilized as baseline reference values for a comprehensive QA program. Results: For clinical commissioning, the MR scanner met the criteria established by the ACR MRI Accreditation Program .The results from ACR phantom showed that image quality specifications were met. The highest spatial frequencies were 9 lp/cm; visualized. The results from the monthly QA demonstrate that variations are within 1% of the commissioning data illustrating good self consistency as regards MRI simulator performance. In‐plane distortion measurements show that the distortion correction algorithm reduced the error to within acceptable (&lt; 1mm at 30mm sup/inf to isocentre and within 2 mm at 120 mm off center) Conclusions: Analysis of the test results indicates consistent and reproducible operation of the wide bore MRI‐SIM unit. A comprehensive commissioning and QA protocol has been developed for use in the radiation oncology setting.

Breast MRI in Community Practice: Equipment and Imaging Techniques at Facilities in the Breast Cancer Surveillance Consortium

MRI is increasingly used for the detection of breast carcinoma. Little is known about breast MRI techniques among community practice facilities. The aim of this study was to evaluate equipment and acquisition techniques used by community facilities across the United States, including compliance with minimum standards by the ACRIN® 6667 Trial and the European Society of Breast Imaging. Breast Cancer Surveillance Consortium facilities performing breast MRI were identified and queried by survey regarding breast MRI equipment and technical parameters. Variables included scanner field strength, coil type, acquisition coverage, slice thickness, and the timing of the initial postcontrast sequence. Results were tallied and percentages of facilities meeting ACRIN® and European Society of Breast Imaging standards were calculated. From 23 facilities performing breast MRI, results were obtained from 14 (61%) facilities with 16 MRI scanners reporting 18 imaging parameters. Compliance with equipment recommendations of ≥1.5-T field strength was 94% and of a dedicated breast coil was 100%. Eighty-three percent of acquisitions used bilateral postcontrast techniques, and 78% used slice thickness≤3 mm. The timing of initial postcontrast sequences ranged from 58 seconds to 8 minutes 30 seconds, with 63% meeting recommendations for completion within 4 minutes. Nearly all surveyed facilities met ACRIN and European Society of Breast Imaging standards for breast MRI equipment. The majority met standards for acquisition parameters, although techniques varied, in particular for the timing of initial postcontrast imaging. Further guidelines by the ACR Breast MRI Accreditation Program will be of importance in facilitating standardized and high-quality breast MRI.

MO‐A‐204C‐02: Breast MRI Quality Control

Quality control of MRI systems used for diagnostic breast MR imaging and biopsy guidance is important to ensure the production of high quality images. Breast MR images may be acquired using dedicated breast MRI scanners, whole body MRI scanners with detachable tabletop breast coils or tables designed with integrated breast coils. 1.5T and 3T multi‐channel arrays are now available. Many of these coils are designed to enable MR‐guided breast biopsy.In May 2010 the ACR launched the ACR Breast Magnetic Resonance Imaging Accreditation Program. The program requires that a medical physicist/MR scientist perform MRI system testing after installation, annually and following major upgrade or repair. Testing must include annual evaluation of all breast imaging and biopsy coils used clinically.Learning Objectives:1. Describe different breast coil designs2. Discuss breast coil quality control procedures3. Provide an overview of the ACR Breast MRI Accreditation Program including quality control requirements

TU‐SAM‐304A‐01: ACR MRI Accreditation Program Update

In October 2008 the American College of Radiology (ACR) expanded the MRI accreditation program to six modules (body, head, MR angiography (MRA), spine, muskuloskeletal and cardiac). The new program enables accreditation of dedicated MR systems, such as those used only for neuro or cardiac imaging, as well as accreditation of special‐purpose MR scanners, such as orthopedic systems. The program introduces a second, smaller ACR phantom, to be used for accreditation and quality control of these small bore orthopedic MR systems.ACR MRI accreditation is now available for a wide range of MRI system configurations and clinical uses. The expansion of the program presents a challenge to the medical physicist, who needs to be aware of which ACR phantom and coil to use for phantom image acquisition, as well as how to address specific image quality issues.Learning Objectives:1. Present the requirements of the new six‐module ACR MRI accreditation program.2. Discuss the medical physicist/MRI scientist qualifications and CME requirements.3. Describe small and large phantom image acquisition and analysis.4. Discuss considerations for low field, 3T, dedicated and special purpose MRI systems in the accreditation and phantom image evaluation process.

WE-C-213A-03: MRI Annual Equipment Performance Evaluation &amp; Acceptance Testing

The ACR MRI Accreditation program requires that sites applying for MRI accreditation submit an annual MRI system performance evaluation performed by a medical physicist or MR scientist. The medical physicist/MR Scientist follows the ACR MRI Quality Control (QC) Manual in order to perform a complete annual system performance evaluation. This evaluation includes an evaluation of the weekly QC performed by a technologist. This presentation shall review a standard set of tests and procedures that satisfy the ACR compliance testing guidelines. A model program for satisfying the ACR MRI performance standards shall be provided. Steps for setting up the QC Program include determining which tests are appropriate, establishing a mutually agreeable testing frequency, training technologist and other personnel to carry out their portions of the MRI QC program, reviewing artifacts and other problems that result from the test data and documenting corrective actions that are taken. Attention will be paid to specific tests, such as Magnetic Field Homogeneity, in which spectral width, phase-difference and bandwidth difference methods will be discussed and compared. Tests for gradient field linearity (geometric distortion) and radio frequency (RF) coil testing will be presented, including measuring slice thickness accuracy, determining mean and maximum signal-to-noise ratios, ghosting ratios and image intensity uniformity. The relevance, applicability, and performance of each element will be discussed. A brief discussion of suggested, additional elements that would constitute an Acceptance Testing (AT) program for Magnetic Resonance Imaging devices will conclude the presentation. Tasks under consideration will include comparing equipment received with purchase order specifications, checking environmental conditions of the MRI suite, RF room shielding survey, cryogen consumption, magnetic field stability, magnetic fringe field survey, gradient field strength, eddy current evaluation, evaluation of image acquisition and image processing software and optional features. Individual testing procedures and the rationale for their use will be presented and performance evaluation acceptance criteria will be suggested. Upon completion of this presentation, participants will understand how to: • Design Quality Control (QC) Testing and Acceptance Testing (AT) programs for Magnetic Resonance Imaging • Define the role of the Technologist, equipment service personnel and the clinical medical physicist/MR scientist in this programs. • Configure the equipment necessary for MRI QC and AT testing.

WE-C-213A-01: ACR MRI Accreditation: Medical Physicist Role in the Application Process

The medical physicist plays an important role in several aspects of the ACR MRI accreditation program. In 2008 significant program changes were made. The new program is modular so that facilities can apply for accreditation in any or all of six clinical modules depending on the practice. Each of the modules allows flexible protocol choices for clinical image submission, while setting minimum requirements for spatial resolution, temporal resolution, and total scan time. Two phantoms are now available to allow accreditation of both large bore magnets and small bore orthopedic MRI systems. During the application or renewal process the physicist can provide expertise to MRI facilities by acquiring the phantom images and assessing whether phantom image quality will meet ACR requirements. When image quality measures fall below standards, the physicist can identify the cause and offer recommendations for corrective action. In addition, prior to acquiring clinical images for accreditation, the physicist can determine whether the site's clinical protocols provide adequate spatial and temporal resolution. Learning Objectives: 1. Present an overview of the new modular ACR MRI Accreditation program as it applies to phantom image acquisition for accreditation application. 2. Discuss phantom image quality failures, possible causes and potential remedies. 3. Provide advice for avoiding common pitfalls in the phantom image submission process.

SU‐FF‐I‐129: A Comprehensive QA Program for Radiotherapy MR Simulators

Purpose: To our knowledge, there are no publications on the acceptance, commissioning and quality assurance (QA) procedures for MR simulators in radiotherapy. The purpose of this work is to develop a comprehensive protocol for MR simulators in radiotherapy. Materials and Method: A GE 1.5T MR scanner was installed in our department in 2006. During acceptance testing and commissioning, the MR scanner was tested according to the standards established by the American College of Radiology (ACR) MRI Accreditation Program. An ACR phantom was used for the study. Our QA protocol includes procedures for geometric accuracy, high‐contrast spatial resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, low‐contrast object detectability, inter‐slice RF interference, fringe field survey, magnetic field homogeneity, eddy currents, coils SNR check and cryogen consumption. We also checked the patient/console intercom 2464_3 2464_4 system, table stop buttons, emergency stop button, table docking, vertical movement, alignment lights and the ventilation system. Monthly QA were developed to check the RF, transmission gain/attenuation, imaging distortion and resolutions using the ACR phantom. A phantom from GE was used for daily QA to check the SNR, RF, isocenter position and the gradients. The lasers installed in the MR room for patient setup were also checked. QA procedures were developed for MR spectroscopy. The results from monthly and daily QA were compared with the commissioning data. Results: The acceptance/commissioning test and monthly QA showed that the MR scanner met the criteria established by the ACR MRI Accreditation Program. The results from the daily QA are SNA: 29.66±0.84; Noise: 2.31±0.1, CTR Frequency: 63860229±4778; iso‐Z: 8916.33±9.26; Gradient X, Y and Z: 100.14±0.11; 100.05±0.08; and 99.8±0.10, respectively, for &gt;2 years. The variations were within 1% of the commission data. Conclusions: A comprehensive QA protocol was developed and routinely used for our MR simulator for radiotherapy.

TU‐SAM‐304A‐02: Clinical Considerations of the ACR MRI Accreditation Program

In October, 2008, the ACR MRI Accreditation Program was updated to a more flexible, modular process. The ACR MR Accreditation process includes the initial application, and the submission of clinical and phantom images and forms.The medial physicist plays a critical role in the accreditation process, along with the lead technologist and the supervising radiologist. A team approach is necessary to ensure that all information is accurate and appropriate for the examinations (both clinical and phantom) submitted for accreditation. The medical physicist should assist the facility in assessing the condition of the scanner as well as optimizing the clinical protocols.This lecture will provide a brief overview of the application steps, and some of the most common problems encountered during clinical portion of the accreditation submission.Learning Objectives:1. Understand the basics of the ACR MR Accreditation process.2. Understand the relationship of the medical physicist in this process as it relates to clinical protocols.3. Understand some of the most common pitfalls and misconceptions in the accreditation process.

The physics components of the ACR MRI Accreditation Program are overly tedious and beyond what is needed to ensure good patient care

Suggestions for topics suitable for these Point/Counterpoint debates should be addressed to Colin G. Orton, Professor Emeritus, Wayne State University, Detroit: ortonc@comcast.net. Persons participating in Point/Counterpoint discussions are selected for their knowledge and communicative skill. Their positions for or against a proposition may or may not reflect their personal opinions or the positions of their employers.

TH‐A‐342‐01: ACR MR Accreditation Update: The Role of the Medical Physicist

In 2006, the ACR council approved a resolution requiring the current ACR MRI Accreditation Program to be redesigned into a modular program. The current program is limited to only whole‐body and cardiac accreditation. The new modular program will offer six clinical modules and is designed to allow a facility to have an accreditation that is more appropriately matched to the individual practice and the patient population being served. The six modules are: body, head, MR angiography (MRA), spine, musculoskeletal and cardiac. A breast MR accreditation program is currently under development; however, will not be one of these MR modules. Instead, it will be part of the Breast Imaging Accreditation Program. Also, an accreditation program specifically designed for special‐purpose orthopedic systems is under development.This continuing education course will review the current status and requirements of the ACR Whole Body MRI Accreditation Program, anticipated changes related to the proposed modular program and anticipated changes in the MRI Quality Control Manual as related to the Annual Medical Physicist Performance Survey.Educational Objectives:1. Review the role of the Medical Physicist in the current Whole Body Accreditation Program with emphasis on the requirements of the annual performance survey.2. Discuss the status of the proposed ACR modular accreditation program as well as the new initiatives into cardiac and orthopedic accreditation and the anticipated impact that these changes will have on the role of the medical physicist.3. Discuss special accreditation considerations related to 3T systems and for systems with parallel imaging capability.

SU‐GG‐I‐122: ACR MRI Accreditation Equipment Performance Evaluation for Various Scanner Settings

Purpose: ACR MRI Accreditation program was created a decade ago for assessing performance by various facilities. Accreditation was voluntary at that time. Recently many stand‐alone MRI imaging centers/clinics seek accreditation because it is now mandatory by some insurance companies. For ACR MRI physics survey/system performance evaluation, it is closely correlated with the equipment performance. It is a challenging task to survey a variety of magnets in different field strength, configurations, and with many software versions/optional packages. The purpose of this work is to summarize ACR MR system evaluation and ACR phantom test experience. Method and Materials: GE, Siemens, Philips, and Hitachi's MRI magnets, in fixed or mobile setup, ranging from 0.3T, 0.7T, 1.0T, 1.5T, to 3.0T are surveyed. Both ACR and site T1/T2 scan protocols are used. Results: It is found that when an MRI scanner is properly maintained, geometric accuracy, slice thickness accuracy, and percent signal ghosting is usually within the limit regardless of fixed or mobile setup, or field strength of the magnet. However, intensity uniformity and low contrast detectability are most demanding for very low field (&lt;0.5T) and 3.0T magnets. At a low magnetic field, it is caused by low signal to noise ratio. For a 3.0T magnet, it is caused by low RF penetration at high field strength, and a much higher acceptable limit for low contrast detectability. In some cases, site protocol for T1 and T2 pulse sequences is required to pass the ACR phantom test. Conclusion: The ACR MRI phantom testing items are designed for different scanner performance criteria. When a testing result is out of the ACR acceptable limit, it is important for the physicist to recognize whether the phantom is not setup properly, or it is caused by scan parameter selection, or a service call is necessary.

TU‐A‐L100E‐01: ACR MR Accreditation: Changes and the Expanding Role of the Medical Physicist

The American College of Radiology MRI Accreditation Program has been active since 1996. As of November 2006, almost 4400 facilities and over 5900 individual MR units had been accredited since the initiation of the program. Until recently, there have been few changes to the accreditation requirements since the program was initiated. However, the ACR recently expanded the original Whole Body MRI Accreditation Program to include 3T systems and very recently announced a Cardiac MRI Accreditation Module. Additional modules, such as a Breast MRI Accreditation Module, are under development. In addition, the MRI Quality Control Manual, first printed in 2001 and revised, with minor changes, in 2004, is currently under revision.This continuing education course will review the current status and requirements of the ACR Whole Body MRI Accreditation Program, the requirements for and issues related to 3T system accreditation, and the recently released Cardiac MRI Accreditation Module. In addition, this course will focus on the expanding roles of medical physicists outside of the conventional ACR MR Accreditation Program involvement.Educational Objectives:1. Review of the current ACR Whole Body MRI Accreditation Program requirements and current program statistics.2. Review the recent modifications of the ACR MRI Accreditation Program, including the 3T scanner requirements as well as the requirements of the new Cardiac MRI Accreditation Module.3. Review the status of other MR initiatives that have been announced by the ACR.4. Outline the expanding role of the medical physicist in MR quality assurance and accreditation.

WE‐B‐ValB‐01: Physics Procedures for ACR MRI Accreditation

In recent years, the American College of Radiology (ACR) Magnetic Resonance Accreditation Program (MRAP) has been adopted by over 3000 sites, nearly half of the estimated MRI facilities in the United States. Those sites agree to follow a weekly QC program set up and monitored by a qualified medical physicist or MR scientist. They also agree to undergo initial and annual equipment performance evaluations by a qualified medical physicist/MR scientist. There are several published documents, including the ACR Phantom Testing Guidance and the 2004 ACR MRI QC Manual, which describe the tests and the performance criteria. These documents are helpful in providing guidance on submitting phantom images for accreditation. However, they allow considerable discretion to physicists doing these tests, and the scanners change more frequently than the published guidance.A consulting medical physicist may see a variety of scanners, each for a short period of time, and needs to provide the sites with useful recommendations beyond the pass/fail status of the phantom tests. The physicist must gather this information from existing data and tests performed with the ACR and other available phantoms. This lecture will describe information which can be derived from those data and how it may be used for improving MR image quality.Educational Objectives:1. Learn the current status of the ACR MRAP program and the role of the medical physicist in that program.2. Understand how to perform required phantom and annual tests on various scanners and the performance criteria for those tests.3. Understand how the results of those tests can be combined and analyzed to troubleshoot problems.4. Understand how QC test and phantom availability and results may vary depending on scanner manufacturer.

SU‐FF‐I‐61: A New Gel Phantom for MRI

Purpose: To develop a gel‐based quality control phantom for MRI that does not suffer from flow artifacts seen in liquid‐based phantoms. Method and Materials: We have developed a gel based phantom incorporating NiCl and NaCl that does not suffer from flow artifacts. The phantom was evaluated for accuracy of the stated T1 and T2 values, uniformity and dehydration properties. The T1 relaxation time was measured using a spin echo sequence with TR = 1000 mS and TE varied between 10 mS and 350 mS. The T2 relaxation time was measured through a fast spin echo inversion recovery sequence with TR = 1000 mS, TE = 50 mS and TI varied between 50 and 983 mS. All measurements and images were made on a GE Signa 1.5T MRI scanner. Results: Measured T1 and T2 values were within 1.3% of the nominal values of 260.3 mS for T1 and 234.1 mS for T2. Uniformity was measured using the ACR T1 sequence of TR = 500 mS, TE = 20 mS. The gel phantom demonstrated a uniformity of 86.5% over its volume in a dedicated head coil, compared to 87.2% for a still liquid phantom in an identical container. The measured mass of 4691 grams did not change over a 6 month period. Conclusion: This new gel phantom shows promise as a replacement for liquid MRI phantoms. Future efforts will focus on adapting the gel to other container geometries and modifying the formulation for more tissue equivalent relaxation times and to match the ACR MRI accreditation program phantom. Conflict of Interest: Research sponsored by Computerized Imaging Reference Systems, Inc.