Introduction

These magnetic resonance (MR) protocols were developed by an expert consensus panel for use on Siemens MR systems and were developed for high-end platform scanners with multichannel phased array coils and parallel reconstruction capabilities. The protocols are divided into 3 sections:

• Body MR imaging
• MR angiography
• Central nervous system (CNS) MR imaging

The protocol parameters can generally be modified to work with other software platforms or releases and hardware configurations but may require small modifications that can be made by a knowledgeable and experienced MR technologist. Scan times may increase in some circumstances.

These protocols provide field strength-specific parameters for 1.5T and 3T. Attention has been given to patient preparation, streamlining the exam, and making the best use of Vueway/Elucirem (gadopiclenol), a recently FDA-approved, high-relaxivity, extracellular gadolinium-based contrast agent (GBCA).

Each protocol contains a brief description of patient preparation, special notes on coil choice and placement, and suggestions for contrast dose, and administration rate, and suggestions concerning timing of triggering, if appropriate.

The consensus panel consisted of the following experts in radiology:

Amish H. Doshi, MD, Bachir Taouli, MD, MHA, Vaneela Ramgolam, RT(R)(MR), MPH and Julianne Stueben, RT(R)(MR) – Icahn School of Medicine at Mount Sinai, New York

MR Protocols for Body MR Imaging

Body magnetic resonance (MR) imaging protocols were developed for 1.5T and 3T systems. Specific protocols include:

• Abdomen
  • Generic Abdomen Pelvis
  • MR Enterography
• Liver
  • Liver
  • MRCP (MR Cholangiopancreatography)
• Pelvis
  • Generic Pelvis Screening
  • Endometrial Cancer
  • Uterine Anomaly and Female Pelvis Benign
  • Rectal Cancer
  • Perianal Fistula
  • Prostate
• Adrenal/Renal
  • Adrenal
  • Renal

General Notes

• Vueway (gadopiclenol; American College of Radiology [ACR] group II GBCA) is injected at a dose of 0.05 mmol/kg, which is half the concentration of other extracellular agents
• Intravenous access should be obtained with a 20- to 24-gauge needle
• We suggest the use of a contrast power injector and a saline flush of a minimum of 20 to 30 mL at the same injection rate as the contrast injection (1.5-2.0 mL/sec), with the exception of prostate imaging which utilizes an injection rate of 4 mL/sec
• Breath-holding is essential for good image quality for abdominal MR imaging. Precontrast images should be used to ensure that the patient can hold breath adequately and understand the instructions. We recommend expiratory breath-holding at end-expiration (end tidal volume)
• When parallel imaging is used, care must be taken to increase the field of view (FOV) sufficiently to avoid residual aliasing artifact. This artifact is more often encountered in coronal imaging, which may require placing the arms over the head or elevating the arms by the patient’s side. Most times, phase oversampling can be used to avoid this when having arms by the side, at the expense of increased scan time
• For T2-weighted acquisitions, consider half-Fourier acquired single-shot turbo spin-echo (HASTE) and Fat Sat HASTE preferably with an adiabatic Fat Sat pulse (SPAIR or ASPIR). It allows a fast, robust application, even when breath holding is compromised
• With a single-shot T2-weighted acquisition, the use of spectral fat saturation is critical for a number of applications. This is particularly true when looking at inflammatory process and the presence of edema, whether it be due to pancreatitis or Crohn’s disease. If fat suppression is problematic in some patients, consider the following solutions: a) region- or volume specific shimming; b) manual frequency adjustment via the “Confirm Frequency” option; and/or c) Short-Tau Inversion Recovery (STIR) sequence variants
• The arterial phase is key for the liver and to some extent the pancreas but is less important for other tissues. When carrying out the multi-station examination protocol, it is important to have the arterial phase captured over the abdomen first, followed by a 2-station (abdomen and pelvis) venous-phase. Fat Sat HASTE transverse is great for the liver and pancreas
• Use diffusion imaging routinely on the liver mainly for lesion and/or infection, as it improves sensitivity
• Avoid repeat MR within 48 hours because of the importance of cumulative dose. Do a careful evaluation, including a determination of estimated glomerular filtration rate, for all patients who are diabetic, are hypertensive, or have history of kidney disease/transplant. Hemodialysis patients should undergo hemodialysis as soon as possible afterwards within a 24-hour window
• For dedicated pelvis imaging, consider BLADE TSE over Cartesian TSE for T2 imaging, especially in the axial and sagittal orientation. BLADE helps reduce subtle motion artifacts due to breathing. But we submit that good image quality is also attainable without BLADE. For optimal quality we also recommend breath holding in the pelvis for 3D T1 spoiled-gradient echo (VIBE)

MR Protocols for MR Angiography

Magnetic resonance (MR) angiography protocols were developed for 1.5T and 3T systems and include:

• MR Venography (MRV) Abdomen Pelvis
• MR Angiography Abdomen Pelvis
• Chest MR Angiography

The rationale for the patient preparation for contrast-enhanced MR angiography is based on a hypothetical generic patient. Individual protocols may include important variations and will be delineated in the specific protocol.

General Notes

• Protocols utilize CARE Bolus/BolusTrak dynamic imaging for bolus detection, but you may choose to use a timing run or scan delay for MR angiographic exams
• Clear liquids only for 4 hours prior to exam is suggested
• Intravenous access should utilize an 18- to 22-gauge needle, preferably inserted in the antecubital fossa. Right side is preferred for thoracic or carotid MR angiography
• A power injector is highly recommended with a 20- to 25-mL saline flush delivered at the same injection rate as the contrast injection
• Breath holding is critical to good image quality for thoracic or abdominal MR angiography. Precontrast or practice scans help ensure that the patient can both breath hold adequately and understand the instructions. Go
  to three-dimensional (3D) and instruct breath hold when the bolus reaches an area of interest
• For all MR angiography scans,
  • Each patient will need an angiographic catheter of adequate size for an injection rate of 1.5-2 mL/sec
  • On precontrast 3D MR angiography, coach breath hold by simulating 20 seconds of fluoro/dynamic bolus triggering, then check 3D images for motion artifacts. This practice run greatly improves the main patient-controlled variable of breathing motion
  • Prescribe 3D dynamic acquisition to cover the anatomy of interest. 3D sequences should be run preinjection and at least 2 times postinjection
  • You may need to alter field of view (FOV) or slab coverage for different-sized patients. Use rectangular FOV to control scan time if possible
  • Timing should be acquired by either a timing bolus of 1 to 2 mL or fluoro/dynamic bolus triggering
  • Double check the K space filling so there is a minimum delay to prevent the late arrival of contrast
• When parallel imaging is used, care must be taken to not have wraparound artifact encroach on the vascular structures. This generally requires prescribing a large FOV beyond the body wall, and for abdominal imaging, it requires placing the arms over the head or elevating the arms at the patient’s side

MR Protocols for Central Nervous System (CNS) MR Imaging

Imaging has evolved to include efficient methods for neuroimaging at both 1.5T and 3T. The central nervous system (CNS) section suggests multiple consensus methods for optimizing examination of patients undergoing magnetic resonance (MR) imaging.

• Brain
  • Routine Adult Brain
  • MRA Head without contrast
  • MRA Head
  • MRA Neck
  • MR Venography Head
  • Aneurysm (3T)
  • Motion Brain
  • Routine Stroke Brain
  • Tumor Brain
  • Multiple Sclerosis Brain
  • Epilepsy Brain
• Specialty Brain
  • Pituitary
  • Internal Auditory Canals
• Head and Neck
  • Orbits
  • Neck
  • Sinuses/Face
• Spine
  • Cervical Spine 1.5T and 3T
  • Thoracic Spine 1.5T and 3T
  • Lumbar Spine 1.5T and 3T
  • Total Spine Routine 1.5T and 3T
  • Brachial Plexus

General CNS Protocol Notes

• Routine adult brain. There are several methods for obtaining T1-weighted images at 3T. Four widely used techniques are presented as options: spin echo (SE), turbo spin echo (TSE), T1 fluid-attenuated inversion recovery (FLAIR), and three-dimensional gradient echo (3D GRE). At 1.5T, an option is to add a magnetization transfer (MT) T1-weighted SE sequence in 1 plane that will increase contrast enhancement effects. Some users add fat saturation to T2 imaging as an option, or T2 FLAIR postcontrast
• Spine imaging. Cervical, thoracic, and lumbar imaging all use sagittal and axial T1- and T2-weighted sequences. There are personal preferences for choosing the desired T1 and T2 method. T1 TSE is a common choice, but additional T1-weighted imaging alternatives are supplied
• TSE short tau inversion recovery (STIR) is valuable for detection of intramedullary lesions and in the trauma patient to evaluate ligamentous injury, while gradient echo T2* techniques are valuable in trauma to visualize hemorrhage
• At 3T, 3D sequences – VIBE for T1-weighting and SPACE for T2-weighting — are good quality options
• Cervical spine. The basic Axial T2-weighted options are TSE and 2D and 3D GRE (MEDIC, CISS, FLASH, or FISP). Axial FSE and TSE inversion recovery (IR) works best to evaluate the spinal cord parenchyma
• Lumbar spine. Axial sequences may be stacked or angled to the disc space. For trauma patients, stacked sequences are ideal to eliminate the possibility of missing a fracture or spinal cord injury 

Notes Relevant for All Neurological Evaluations by MR imaging

• T1. At 3T, no optimum T1-weighted sequence exists yet. Options are to use SE, TSE, gradient, and FLAIR. At 1.5T, SE generally is used, although alternatives are also presented
• T2. Most sites use TSE sequences rather than SE. BLADE acquisitions assist with patient motion, but highlight abnormalities less well. FLAIR is useful for lesion detection
• Susceptibility. A T2-weighted gradient echo sequence can be used to detect blood products and microhemorrhages. This approach is especially useful in cases of possible stroke and in trauma patients. Susceptibility-weighted imaging (SWI) or GRE T2 are the two sequences generally used
• Diffusion.Most brain protocols include a diffusion-weighted imaging sequence that is useful for stroke, infection, and tumor imaging. Apparent diffusion coefficient maps should be included to evaluate actual diffusion properties and eliminate T2 shine-through
• Perfusion.While not currently used routinely, perfusion-weighted imaging is becoming increasingly important and can provide clinically significant information regarding blood volume and/or transit time for both stroke and tumor imaging. If perfusion imaging is used, power injection over hand bolus is the optimum way for injection
• Contrast.The protocols presented here do not list separate imaging sequences for contrast-enhanced imaging; rather, the T1-weighted sequence of choice is typically repeated after
  contrast agent administration. Some protocols use fat saturation after contrast or MT to better depict enhancement. T2-weighted FLAIR is also an alternative. Most neurologic examinations
  with contrast are acquired with at least a 3- to 5-minute delay after the contrast injection to optimize visualization of disorders of the blood-brain barrier. The method of injection is
  not important in these cases, and a manual injection is typically used. However, power injectors are needed for contrast-enhanced MR angiography and perfusion imaging. Rates of injection
  vary, but 4 to 5 mL/sec is standard for perfusion, and 1.5 to 2.0 mL/sec is used for MR angiography. Dosing of gadopiclenol is weight-based at 0.05 mmol/kg (half the dose of other extracellular
  agents) for most protocols. The dose for an individual injection may be lower for split-dose protocols (e.g., involving multiple first-pass pituitary exams, etc. Keep overall dose within the standard
  0.05 mmol/kg guideline. The ACR has recommended that the lowest dose feasible be used for diagnostic purposes; because standard dosing recommendations are mostly influenced by lean body mass,
  and extracellular fluid volume in fatty tissues is low, it is reasonable to cap the upper limit of gadopiclenol for heavier adults at 15 mL total (the largest single dose vials and prefilled
  syringes are 15 mL)
• MR angiography. The use of MR angiography in stroke and for vascular assessment is rapidly advancing. Contrast-enhanced MR angiography has mostly replaced noncontrast methods of carotid evaluation. Dynamic methods, such as time-resolved imaging of contrast kinetics (TWIST), have some advantages since they provide information similar to that obtained by catheter angiography. Noncontrast 3D time-of-flight methods are usually used for intracranial evaluation
• Power injectors are needed for contrast-enhanced MR angiography, dynamic MR angiography, and perfusion imaging.
  For contrast-enhanced and dynamic MRA, improved image quality can be obtained with an injection rate of 1 to 2 mL/sec.
  For perfusion, the rate of injection is usually 4 to 5 mL/sec. Dosing is weight based, at a single dose level in most circumstances.
  A saline bolus chaser is preferred. At 3T, the dose may be reduced if desired. The renally impaired patient requires special consideration prior to contrast administration