{
"id": "mri-procedures",
"modality": "MRI",
"category": "Procedures",
"title": "MRI Procedures: Protocols, Coils and Anatomy",
"minutes": 9,
"slides": [
{
"id": 1,
"diagram": "title",
"heading": "MRI Procedures",
"bullets": [
"57 of 200 scored questions (28.5%)",
"Neuro 25, body 15, musculoskeletal 17",
"Coils, positioning, planes and protocols"
],
"narration": "Welcome to MRI Procedures. This category is 57 of the 200 scored questions, or 28.5 percent of the MRI boards. ARRT splits it into neurological at 25 questions, body at 15, and musculoskeletal at 17, so neuro is the biggest single chunk. For each region we'll focus on what the exam loves: which coil and position to use, how to angle your planes to the anatomy, the core sequences, and the classic look of common pathology. Let's start with the brain.",
"svg": ""
},
{
"id": 2,
"diagram": "brain-acpc",
"heading": "Brain: routine, MS, stroke",
"bullets": [
"Head coil, supine, head first, landmark nasion",
"Axials parallel to the AC-PC line",
"Sag T1, ax T2, FLAIR, DWI/ADC, T2* or SWI",
"MS: sagittal FLAIR shows Dawson's fingers",
"Acute stroke: DWI bright, ADC dark"
],
"narration": "For a routine brain, use the head coil with the patient supine, head first, landmarked at the nasion. Prescribe axial slices parallel to the line between the anterior and posterior commissures, the A C P C line. The core protocol is sagittal T1, axial T2, axial FLAIR, axial diffusion with an A D C map, and axial T2 star or susceptibility weighted imaging. Add post gadolinium T1 for tumor, infection or MS activity. For multiple sclerosis, sagittal FLAIR shows plaques running perpendicular to the ventricles, called Dawson's fingers. In acute stroke, diffusion is bright and A D C is dark.",
"svg": ""
},
{
"id": 3,
"diagram": "neuro-planes",
"heading": "Seizure, sella, IACs, orbits",
"bullets": [
"Seizure: coronals perpendicular to hippocampus",
"Pituitary: thin sag and cor T1, dynamic post",
"IACs: thin T1 pre and post, 3D T2 for CN 7 and 8",
"Orbits: fat-sat post T1; eyes closed and still"
],
"narration": "Some neuro exams depend on special planes. For seizure, prescribe thin coronal T2 and FLAIR perpendicular to the long axis of the hippocampus, not to the A C P C line, and add a 3D T1 volume. For the pituitary, use a small field of view with thin sagittal and coronal T1 before and after contrast. A dynamic coronal series catches microadenomas, which enhance later than normal gland. For the internal auditory canals, use thin T1 pre and post gadolinium plus high resolution 3D T2 through cranial nerves 7 and 8. For orbits, fat suppress the post contrast T1, and have the patient close their eyes and keep still.",
"svg": ""
},
{
"id": 4,
"diagram": "spine-satband",
"heading": "Spine protocols",
"bullets": [
"Spine coil, supine; sag T1, T2, STIR, axial T2",
"Localizer to C2 to count levels",
"Sat band anterior to vertebral bodies",
"Post-op: scar enhances, recurrent disc does not",
"Gibbs truncation can mimic a syrinx"
],
"narration": "For the spine, use the posterior spine coil with the patient supine. The core protocol is sagittal T1, sagittal T2, sagittal STIR for marrow edema and fractures, and axial T2. To count thoracic levels correctly, use a large sagittal localizer that includes C2. Place a saturation band anterior to the vertebral bodies to remove swallowing, cardiac, aortic and bowel motion ghosts. In a post-op lumbar spine, give gadolinium and scan promptly: scar enhances right away, but recurrent disc does not enhance centrally. And remember, Gibbs truncation lines in the cord can mimic a syrinx, so increase the phase matrix to check.",
"svg": ""
},
{
"id": 5,
"diagram": "tof-satband",
"heading": "Head and neck MRA and MRV",
"bullets": [
"Circle of Willis: 3D TOF, review with MIP",
"Arterial TOF: sat band superior to kill veins",
"MRV: sat band inferior to kill arteries",
"TOF can overestimate stenosis",
"Subacute blood is bright on TOF, mimics flow"
],
"narration": "Time of flight, or TOF, makes fresh inflowing blood bright. For the circle of Willis, use 3D TOF and review it with maximum intensity projections, or MIPs, plus the source images. The saturation band goes on the side the unwanted flow comes from. For arterial TOF of the head and neck, place it superior to remove venous signal. For an MR venogram, place it inferior to remove arterial signal. Turbulent flow past a stenosis loses signal, so TOF can overestimate stenosis. And short T1 tissue, like subacute hemorrhage, is bright on TOF and can mimic a vessel.",
"svg": ""
},
{
"id": 6,
"diagram": "in-out-phase",
"heading": "Abdomen, liver and MRCP",
"bullets": [
"Breath-holds at end-expiration",
"Fat drops on out-of-phase; iron drops on in-phase",
"Portal venous phase about 60-70 s after injection",
"Gadoxetate: hepatobiliary phase about 20 min",
"MRCP: heavy T2, NPO 4 h; stones are dark"
],
"narration": "Abdominal imaging uses a torso phased array with breath-holds at end expiration, because expiration is more reproducible. In and out of phase gradient echo is a favorite: fat in a voxel drops signal on the out of phase images, while iron drops signal on in phase, the longer echo time. At 1.5 tesla those echo times are about 2.2 and 4.4 milliseconds. Dynamic liver imaging includes a portal venous phase at about 60 to 70 seconds. Gadoxetate adds a hepatobiliary phase at about 20 minutes. MRCP uses heavy T2 weighting after about 4 hours with nothing by mouth. Stones are dark filling defects.",
"svg": ""
},
{
"id": 7,
"diagram": "breast-kinetics",
"heading": "Breast and pelvis",
"bullets": [
"Breast: prone, bilateral coil, no compression",
"Premenopausal: scan cycle days 7-14",
"Type III washout curve is suspicious",
"Implant study: silicone sequences, no contrast",
"Prostate: cancer dark on T2, restricts on DWI"
],
"narration": "For breast MRI, the patient is prone in a dedicated bilateral breast coil, with breasts hanging freely and no compression. Schedule premenopausal patients in the second week of the cycle, about days 7 to 14, to reduce background enhancement. Dynamic fat suppressed T1 before and after gadolinium produces kinetic curves. Type one persistent is usually benign, type two plateau is indeterminate, and type three washout is suspicious for cancer. A silicone implant study uses silicone selective sequences and needs no contrast. In the prostate, cancer is dark on T2 and restricts on diffusion, usually in the peripheral zone.",
"svg": ""
},
{
"id": 8,
"diagram": "magic-angle",
"heading": "Shoulder, knee, magic angle",
"bullets": [
"Shoulder: thumb up, neutral or slight external rotation",
"Oblique coronal parallel to supraspinatus",
"Knee sagittals angled about 10-15 degrees to ACL",
"Meniscal tear: signal reaches articular surface",
"Magic angle: tendon at 55 degrees, short TE"
],
"narration": "For the shoulder, use a dedicated coil with the arm at the side, thumb up, in neutral or slight external rotation. Internal rotation overlaps the tendons. Prescribe oblique coronals parallel to the supraspinatus tendon, the most commonly torn rotator cuff tendon. For the knee, flex it slightly, and angle the sagittals about 10 to 15 degrees to run parallel to the anterior cruciate ligament. A meniscal tear is signal that reaches an articular surface, best on short echo time proton density images. Finally, magic angle: tendon fibers at about 55 degrees to B zero look bright on short echo time sequences. Check a long echo time T2.",
"svg": ""
},
{
"id": 9,
"diagram": "msk-table",
"heading": "Hips, joints and masses",
"bullets": [
"Hips: feet internally rotated about 15 degrees",
"Occult hip fracture: bilateral coronal T1, STIR",
"TMJ: oblique planes, open and closed mouth",
"Ankle: ATFL best seen on axials",
"Soft tissue mass: skin marker, cover compartment"
],
"narration": "For hips and the bony pelvis, internally rotate and tape the feet about 15 degrees to elongate the femoral necks. For a suspected occult hip fracture, start with large field of view bilateral coronal T1 and STIR. For the temporomandibular joints, use small bilateral coils, angle oblique sagittals perpendicular to each condyle's long axis, and scan with the mouth closed and open to see the disc move. At the ankle, the anterior talofibular ligament, the most commonly sprained, is best seen on axials. For a soft tissue mass, place a skin marker over the lump and cover the whole compartment.",
"svg": ""
},
{
"id": 10,
"diagram": "summary",
"heading": "Lock these in",
"bullets": [
"Brain axials parallel to the AC-PC line",
"Arterial TOF: sat band superior; MRV: inferior",
"Post-op spine: scar enhances, disc does not",
"Breast prone; type III washout is suspicious",
"Magic angle: 55 degrees to B0 on short TE"
],
"narration": "Let's lock it in. Brain axials run parallel to the A C P C line, while seizure coronals run perpendicular to the hippocampus. For arterial time of flight, the saturation band goes superior, and for an MR venogram, it goes inferior. In a post-op spine, scar enhances and recurrent disc does not. Breast MRI is done prone, and a type three washout curve is suspicious for cancer. And magic angle appears when a tendon sits about 55 degrees to B zero on short echo time sequences. Great job, and keep reviewing.",
"svg": ""
}
]
}