MSK MRI

Shoulder MRI in Real Practice: From Rotator Cuff to Instability | Core Cases

MSK MRI — Fri, 20 Feb 2026 13:07:51 +0900

Shoulder MRI is not about memorizing signs.
It’s about recognizing patterns in real cases.
In this 1 hour 50 minute session,
I walk through essential shoulder MRI findings
from rotator cuff tears to instability and adhesive capsulitis.
If you’d like to see how these cases look in daily practice,
you can watch the full lecture here.

Video Timeline

00:01:17 – Supraspinatus & Infraspinatus Anatomy (SST / IST)
Detailed MRI-based review of footprint anatomy, tendon orientation, and muscle–tendon relationships.
00:07:14 – Rotator Cuff Tears
How to distinguish tendinosis from partial- and full-thickness tears.
Key MRI signs, retraction patterns, and common pitfalls.
00:22:44 – Subscapularis Anatomy
Insertional footprint, biceps pulley relationship, and sagittal/coronal MRI landmarks.
00:33:04 – Subscapularis Tears
Upper-border tears, concealed lesions, and associated biceps pathology.
What surgeons want in your report.
00:47:04 – Anterior Shoulder Instability
Bankart spectrum, Hill-Sachs lesions, and bipolar bone loss.
Pattern recognition on axial MRI.
01:09:17 – Labral Tears (Including SLAP)
Differentiating normal variants from true pathology.
How to avoid overcalling sublabral recess and Buford complex.
01:33:54 – Adhesive Capsulitis
Axillary capsule thickening, rotator interval changes, and staging on MRI.

#ShoulderMRI #MSKMRI #Radiology #MusculoskeletalRadiology #RotatorCuff #Subscapularis #LabralTear #ShoulderInstability #SLAPLesion #AdhesiveCapsulitis #OrthopedicImaging #MRIeducation #RadiologyTeaching #RadiologyResident #medicaleducation

Sagittal Wrist MRI Anatomy_Ulnar-Sided Stabilizing System

MSK MRI — Sun, 1 Feb 2026 09:10:42 +0900

https://youtu.be/kOoXWzWtoYM

https://youtube.com/shorts/gBfJcQGh48I

Concept

On sagittal wrist magnetic resonance imaging,
the triangular fibrocartilage complex should not be read as a single disc.
It represents a continuous ulnar-sided stabilizing system connecting the distal radioulnar joint to the ulnocarpal joint.

Central Anchor — Articular Disc

The articular disc lies at the center of the triangular fibrocartilage complex.
Its dorsal and volar margins are not free edges.
They blend directly into the dorsal and volar radioulnar ligaments, forming the core stabilizing arms.

Radioulnar Ligaments

Dorsal Radioulnar Ligament

Thickened dorsal peripheral margin of the articular disc.
Extends from the dorsal rim of the distal radius (sigmoid notch)
to the ulnar styloid and fovea of the ulnar head.
Consists of:
Becomes taut in pronation and provides dorsal stability of the distal radioulnar joint.
Blends dorsally with the floor of the extensor carpi ulnaris tendon sheath.

Volar Radioulnar Ligament

Thickened volar peripheral margin of the articular disc.
Originates from the palmar rim of the sigmoid notch and lunate facet of the distal radius.
Also composed of superficial (styloid) and deep (foveal) fibers.
Tightens in supination, acting as the primary volar stabilizer of the distal radioulnar joint.
Serves as the proximal origin for the major palmar ulnocarpal ligaments.

Ulnocarpal Ligaments (Distal Continuation)

Ulnolunate Ligament

Palmar ligament extending from the volar radioulnar ligament region
and indirectly from the ulnar fovea or styloid base.
Inserts on the palmar cortex of the lunate.
Courses distally along the long axis of the forearm.
Helps suspend the lunate and resist palmar and ulnar translation of the proximal carpal row.

Ulnotriquetral Ligament

Palmar ligament arising mainly from the volar radioulnar ligament,
with partial contribution from the palmar-ulnar aspect of the ulnar styloid.
Fans out distally to the proximal and ulnar surfaces of the triquetrum.
Lies just ulnar to the ulnolunate ligament.
Contributes to ulnocarpal stability and load transmission from the ulnar carpus to the ulna.

MRI Take-Home Message

On sagittal wrist magnetic resonance imaging:
disc → radioulnar ligaments → ulnocarpal ligaments
should be followed as one continuous stabilizing chain.
Instability rarely comes from the disc alone.

#DrSlothic #SlothicRadiology #MSKMRI #WristMRI #SagittalMRI #WristAnatomy #TFCC #UlnarSidedWrist #DistalRadioulnarJoint #UlnocarpalLigaments #RadiologyEducation #MSKRadiology #HandWristMRI

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Galeazzi Fracture–Dislocation — Wrist MRI Focus

MSK MRI — Sun, 1 Feb 2026 08:54:19 +0900

https://youtu.be/vvV4DYmUenw

https://youtube.com/shorts/WipVHnQZo3g

Why the wrist matters

Galeazzi fracture is not only a radial shaft injury.
The key problem is often DRUJ instability, caused by disruption of the TFCC stabilizers.

Sagittal MRI: Best plane for ulnar-sided stabilizers

Sagittal imaging clearly demonstrates the TFCC ligamentous components, not just the articular disc.

Normal TFCC Stabilizing Core

The central articular disc is present,
but true DRUJ stability depends on the radioulnar ligaments:

Dorsal Radioulnar Ligament

Dorsal ulnar head → distal radius
Tight in pronation

Volar Radioulnar Ligament

Volar ulnar head → distal radius
Tight in supination

➡️ Tears of these ligaments lead directly to DRUJ instability.

Distal Continuation: Volar Ulnocarpal Sling

The volar radioulnar ligament continues into:

These form the volar ulnocarpal stabilizing sling.

MRI Findings in This Galeazzi Case

Ulnar styloid process fracture
ECU tendon longitudinal splitting
Combined tears of:

Take-home Message

This is not just a fracture.
It is a complete disruption of the ulnar-sided stabilizers, explaining persistent DRUJ instability.

#DrSlothic #SlothicRadiology #MSKMRI #GaleazziFracture #GaleazziFractureDislocation #DistalRadioulnarJoint #DRUJ #ForearmTrauma #OrthopedicRadiology #TraumaRadiology #MSKRadiology #RadiologyEducation #RadiologyPearls #CaseBasedRadiology #OrthopedicImaging #XrayInterpretation #CTinTrauma #PostoperativeImaging

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© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
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Galeazzi Fracture–Dislocation

MSK MRI — Sun, 1 Feb 2026 08:33:43 +0900

https://youtu.be/l45A9QH-cok

https://youtube.com/shorts/3w0zWLzwFsQ

Definition
A fracture of the middle to distal third of the radial shaft associated with dislocation or subluxation of the distal radioulnar joint (DRUJ).
The fracture is obvious; the joint injury is frequently subtle and missed.

Plain Radiograph Checklist

AP view
True lateral view

After Reduction

Improved radial alignment does not ensure stability
Persistent DRUJ incongruity indicates an unstable Galeazzi injury, especially in adults

Role of CT and MRI

CT: confirms residual DRUJ malalignment and associated fractures
MRI: demonstrates TFCC disruption, explaining persistent instability

Take-Home Message
In forearm trauma, do not focus on the fracture alone.
A distal or mid-shaft radial fracture always raises one question:
Where is the ulna relative to the radius?

Missing the DRUJ injury is the critical diagnostic error in Galeazzi fracture–dislocation.

#DrSlothic #SlothicRadiology #MSKMRI #GaleazziFracture #GaleazziFractureDislocation #DRUJ #DistalRadioulnarJoint #ForearmTrauma #OrthopedicRadiology #TraumaRadiology #MSKRadiology #RadiologyEducation

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery
© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
No unauthorized reproduction, redistribution, or use for AI training.

The Most Common Calf Tear Pattern — Don’t Miss the Transverse Tear

MSK MRI — Wed, 28 Jan 2026 20:56:04 +0900

https://youtu.be/jGHQoqG_Zpo

https://youtube.com/shorts/FB--s6N052w

Key Radiologic Points

Clinical Context

Sudden calf pain during uphill running
Sharp pulling sensation
Classic presentation of acute calf strain

Where to Start on MRI

Always begin with axial images
In calf injuries, vertical tears are the diagnostic starting point, not a secondary finding

Key Anatomic Landmark

Focus on the anterior aponeurosis of the medial gastrocnemius
Normally seen as a thin, smooth, arcing low-signal line along the anterior muscle surface

Vertical Tear

Focal interruption of the anterior aponeurosis
Best found by inspecting areas adjacent to muscle edema or hematoma
Once identified, it must be followed slice by slice

How to Find the Transverse Tear

Track the same aponeurosis inferiorly
Look for the sudden disappearance of the aponeurosis
Muscle is present, but the aponeurosis is missing
This combination defines a transverse tear gap

Most Common Pattern: L-Pattern Tear

Primary partial-width transverse tear of the medial gastrocnemius aponeurosis
Associated vertical tear at the lateral margin of the detached segment
Inferior transverse component: usually full-thickness
Vertical and superior components: typically partial-thickness

Important Pitfall

Mild soleus edema may be present
No injury to intramuscular tendons or aponeurotic junctions
Recognize it, but do not let it distract from the primary pattern

Take-Home Message

Vertical tears are the entry point to diagnosis
Always follow them inferiorly to identify the transverse component
Learn the L-pattern tear — it is the most common calf tear pattern
Pattern recognition makes the diagnosis straightforward

#DrSlothic #SlothicRadiology #MSKMRI #CalfTear #CalfStrain #Gastrocnemius
#SportsMRI #MuscleInjury #PatternRecognition #RadiologyEducation

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery
© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
No unauthorized reproduction, redistribution, or use for AI training.

Why This Is NOT a Strain — Muscle and Nerve Tell the Story

MSK MRI — Tue, 27 Jan 2026 23:54:17 +0900

https://youtu.be/Jo7G45QgSRw

Muscle edema doesn’t always mean strain.
These cases represent crush injury.
Read them like strain, and you will miss what matters.

Case 1 — Muscle Crush Injury (Triceps-dominant)

Mechanism: Direct industrial anterior–posterior compression of the upper arm
MRI (fat-suppressed T2):
Peripheral fascial fluid tracking and perifascial edema present
Myotendinous junction relatively spared
Dominant involvement of the muscle belly, not the tendon
Subtle brachialis involvement with adjacent subcutaneous edema
→ Muscle compressed between bone and subcutaneous layer

Interpretation:
Compression-related muscle belly injury → true muscle crush injury, not strain or DOMS.

Case 2 — Radial Nerve Involvement in Crush Injury

Clinical: Arm numbness and finger extension weakness, no humeral fracture
Anatomy: Radial nerve vulnerable at the spiral groove, directly against bone
MRI findings:
Associated brachialis intramuscular hematoma and muscle edema

Interpretation:
Nerve injury occurs within the same global crush pattern
→ Compression-related neuropathy (neurapraxia to axonotmesis)

Key reporting phrase:

“No definite nerve transection is identified.”

Final Take-Home Message

Crush injury is a distinct trauma entity
Muscle clues:
Nerve clues:
Always interpret muscle and nerve together, guided by mechanism and anatomy

#CrushInjury #MuscleCrush #TraumaticMyopathy #CompressionInjury #RadialNerveInjury #MSKMRI #MuscleEdema #NotAStrain #RadiologyEducation #PatternRecognition #DrSlothic #SlothicRadiology #MSKMRI

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery
© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
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When Elbow Edema Isn’t a Tear — MRI Clues to Delayed onset muscle soreness

MSK MRI — Mon, 26 Jan 2026 23:27:40 +0900

https://youtu.be/LsSVBuJ9MV8

https://youtube.com/shorts/aqm32avcGcA

Radiologic Essentials

1. Start With the Pattern
• Fluid-sensitive sequences show diffuse or patchy high signal
• Typically involves multiple muscles within a functional group
• This distribution immediately argues against a focal traumatic tear

2. Architecture Is the Key Anchor
• Fascicular architecture remains intact
• No macroscopic fiber disruption, retraction, or large hematoma
• Muscle bulk may be mildly increased but remains organized

3. Location Helps Exclude Strain
• Signal abnormality is not MTJ-centered
• More generalized involvement of the muscle belly
• Unlike Grade 1 strain, no feathery MTJ-tracking edema

4. Don’t Ignore the Fascia
• Deep fascial edema is commonly present
• Fascia has high nociceptor density and acts as a major pain generator
• Explains pain that appears disproportionate to structural findings

5. Expect MRI–Clinical Dissociation
• STIR/T2 hyperintensity may persist weeks to months
• Imaging abnormalities often outlast symptom resolution
• Persistent edema does not equal ongoing injury

Radiologic Take-Home Message

Diffuse, reversible muscle ± fascial edema
with preserved internal architecture
→ favors Delayed Onset Muscle Soreness (DOMS)
→ a functional muscle disorder, not a structural tear

#SportsMRI #DOMS #MuscleEdema #ElbowMRI #MSKRadiology
#SportsImaging #PatternRecognition #RadiologyEducation #DrSlothic #SlothicRadiology #MSKMRI

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery
© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
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Localized Tenosynovial Giant Cell Tumor of the Knee

MSK MRI — Sat, 24 Jan 2026 17:03:49 +0900

https://youtu.be/r7fwv37CAsU

https://youtube.com/shorts/OtO-fqnDCpc

MRI as the Diagnostic Gold Standard

MRI is the key modality for diagnosing localized TGCT (L-TGCT), defining extent, and planning surgery.
Its multiplanar capability and soft-tissue contrast reliably differentiate L-TGCT from other intra-articular masses.

Key MRI Findings (Imaging-Focused)

Morphology

Solitary, well-circumscribed, lobulated nodular mass
Distinct from diffuse TGCT (no carpet-like synovial infiltration)
Often encapsulated by a thin low-signal pseudocapsule

T1-Weighted Imaging

Low to intermediate signal, usually iso–slightly hypointense to muscle
Helps exclude lipoma and simple subacute hematoma

T2 / Fluid-Sensitive Imaging

Heterogeneous signal
Occasional cleft-like hyperintensity between lobules

GRE / SWI

Blooming artifact from hemosiderin (may be subtle in localized type)
Absence of marked blooming does not exclude L-TGCT

Post-Contrast (T1 C+)

Moderate to intense, heterogeneous enhancement
Differentiates from ganglion cyst (rim only) and hematoma (no internal enhancement)

Key Differentials (MRI Clues)

Fibroma of tendon sheath: very low T1/T2, no blooming, less heterogeneous enhancement
Synovial hemangioma: very high T2, serpentine vessels, phleboliths
Synovial sarcoma: T2 triple signal, calcification, aggressive growth
Synovial chondromatosis: multiple cartilaginous nodules, calcification/ossification
Hoffa’s disease: diffuse fat-pad edema or fibrosis, no discrete blooming nodule

Take-Home

A synovium-based nodular mass with low T2 signal, (variable) blooming on GRE, and heterogeneous enhancement strongly favors localized TGCT, especially when morphology and evolution do not fit postoperative fibrosis.

Hashtags
#LocalizedTGCT #TenosynovialGiantCellTumor #KneeMRI #MSKRadiology #IntraArticularMass
#T2LowSignal #GREBlooming #SynovialTumor #DifferentialDiagnosis #RadiologyEducation #DrSlothic #SlothicRadiology

Visualizing MSK Radiology: A Practical Guide to Radiology Mastery
© 2022 MSK MRI Jee Eun Lee All Rights Reserved.
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Cyclops Lesion After ACL Reconstruction

MSK MRI — Sat, 24 Jan 2026 11:47:12 +0900

https://youtu.be/C_AfNeh7Fkk

https://youtube.com/shorts/X5KaN_j65m8

A Practical MRI Guide for Radiologists

Cyclops lesion, or localized anterior arthrofibrosis, is one of the most common and most easily overcalled findings after ACL reconstruction.
Because it is familiar, it often becomes a reflex diagnosis.
This is exactly why understanding its typical timing, location, and behavior matters.

What a True Cyclops Lesion Looks Like

Clinical context

Develops early, typically within the first postoperative year
Often associated with loss of terminal extension, sometimes with a “cyclops clunk”

Typical MRI location

Anterior intercondylar notch
Immediately anterior to the tibial insertion of the ACL graft
Often gently displaces the posterior margin of Hoffa’s fat pad
Does not track along synovium

Morphology

Small, well-circumscribed nodular mass
Ovoid or bulbous
Stable in size over time

Signal characteristics

T1-weighted: low to intermediate signal
T2 / PD fat-sat: heterogeneous, but not markedly low
STIR: relatively hyperintense (granulation component)
GRE / SWI: no susceptibility blooming

Why Cyclops Lesions Form

Cyclops lesions represent a localized fibroproliferative response related to:

Surgical debris from tibial tunnel drilling
Residual ACL stump tissue
Early graft impingement
Postoperative inflammatory milieu

Importantly, they form early and typically do not continue to grow over years.

When You Should Stop Calling It Cyclops

Be cautious if an anterior notch lesion:

Appears many years after surgery
Progressively enlarges
Becomes lobulated
Evolves to predominantly low T2 signal
Shows hemorrhagic signal or GRE blooming

That pattern is not typical for postoperative arthrofibrosis and should prompt consideration of synovial-based pathology, particularly localized tenosynovial giant cell tumor.

Take-Home Message

Cyclops lesion is not just a location-based diagnosis.
Timeline, stability, and signal behavior matter.
Early, small, stable, anterior to the tibial ACL insertion — that is cyclops.
Growth and signal evolution over time mean you should rethink the diagnosis.

#CyclopsLesion #ACLReconstruction #KneeMRI #MSKRadiology #PostoperativeMRI #AnteriorIntercondylarNotch #Arthrofibrosis #RadiologyEducation #DrSlothic #SlothicRadiology #DrSlothic #SlothicRadiology

Bennett Lesion and Posterosuperior Internal Impingement: A Common Pitfall

MSK MRI — Tue, 20 Jan 2026 22:38:10 +0900

https://youtu.be/ydNTiB5sZVo

https://youtube.com/shorts/BKlONA0UWag

https://youtube.com/shorts/6yHDS7sore4

Watch Related Shorts

Bennett Lesion: What It Really Represents on Shoulder CT

https://youtube.com/shorts/BKlONA0UWag

Labral Calcification: The MRI Low-Signal Trap

https://youtube.com/shorts/_UNZ5r3dH1M

Hill-Sachs fracture??— Same CT Look, Different Mechanism

https://youtube.com/shorts/6yHDS7sore4

Let’s look at a case and ask two simple questions.

Case Overview

On radiographs and CT:

Extra-articular ossification / exostosis along the glenoid rim
Irregular, elongated, crescent-shaped bony density
Well-corticated margins → chronic process
Adjacent glenoid rim sclerosis
Not a loose body

Clinical context:

Long-term amateur baseball pitcher

→ Diagnosis: Bennett lesion

Bennett lesion is a chronic traction-related exostosis arising from the posteroinferior glenoid rim,
representing traction enthesopathy at the posterior capsulolabral attachment,
related to repetitive stress in abduction and external rotation, especially the late cocking phase.

Question 1 — Same Area, Different Diagnosis

Another patient shows:

Amorphous, high-attenuation intra-articular calcification
Localized to the posterosuperior labrum
Bulky, partially fragmented deposit
MRI: marked edema and labral contour loss

Clinical context:

59-year-old woman
Acute severe shoulder pain for 4 days

→ This is not a Bennett lesion.
→ Basic Calcium Phosphate deposition of the labrum (acute calcific labritis).

Question 2 — Hill-Sachs Fracture?

In the Bennett lesion case:

Subtle posterior humeral head flattening is present

Compare with a true anterior instability case:

Bony Bankart lesion
Medially displaced fragment
Classic Hill-Sachs fracture

Back to the Bennett lesion patient:

No anterior instability
No bony Bankart lesion

→ Not a Hill-Sachs fracture

So What Is It?

This represents posterosuperior internal impingement.

In abduction and external rotation,
the glenohumeral contact point shifts posterosuperiorly
Leads to repetitive shear stress
Affects the undersurface of the rotator cuff and posterosuperior labrum

Typical MRI Findings

Posterior/posterosuperior humeral head cysts
Articular-sided partial-thickness tears
Undersurface fraying, not bursal-sided
Posterosuperior labral tear
Often associated with Bennett lesion or posterior capsular tightness

Take-Home Message

If a CT looks like a Hill-Sachs fracture but the anterior instability pattern is absent,
think chronic remodeling from posterosuperior internal impingement, not a fracture.

#DrSlothic #SlothicRadiology #BennettLesion #HillSachs #InternalImpingement #ShoulderCT #ShoulderMRI #SportsRadiology #MSKRadiology #RadiologyPitfalls