1) The document discusses various normal anatomical structures and imaging artifacts that can be mistaken for abnormalities in MRI of the wrist and elbow joints. 2) Specific examples mentioned include "pseudoerosions" of wrist bones that are actually intraosseous blood vessels, as well as pseudodefects of the capitellum and trochlear bones of the elbow that appear as interruptions of the cortical bone. 3) The document emphasizes that these pseudodefects should not be confused with osteochondral lesions, as they do not exhibit marrow edema and occur in different locations. It provides images to illustrate examples of these normal variants.

1. Dr/ ABD ALLAH NAZEER. MD.
Artifacts and Pitfalls of the Wrist and Elbow Joints.

7. In 13% of examined wrist we noted
"pseudoerosion". All cases
intraosseous blood vessels
nutritional canals were visible in all
individuals, most commonly in
capitate and lunate bones. We
present possible diagnostic pitfalls in
MR images of Rheumatoid patients.

8. Sagittal, Coronal and Axial T1 Turbo 3D magnetic resonance
image demonstrates "pseudoerosion" of the capitate bone.

9. Sagittal and Axial T1 Turbo 3D
magnetic resonance image
demonstrates "pseudoerosion"
of the lunar bone.

10. Wraparound artifact. MR image of the wrist shows wraparound artifact, with
structures from outside the FOV mapped into the image. The phase-encoding
direction is parallel to the long axis of the hand and wrist; the more proximal
and distal cross sections are mapped into the section of interest.

11. Normal hyperintense triangular ligament striation, ligamentum
subcruentum and TFCC degeneration may mimic a tear.

12. Bright hyaline cartilage mimics tear.

13. Bright signal along the radial attachment resemble tear.

14. Triangular ligament. (a) Coronal 2D GRE T2*-weighted MR image (1.5-mm section thickness, 50-mm FOV, 224 × 512
matrix with ZIP) shows the triangular ligament. The proximal lamina of the ligament attaches to the fovea of the
ulnar styloid process (dashed arrow). The distal lamina attaches to the tip of the ulnar styloid process (solid arrow)
(12-14). The region of increased signal intensity between the laminae is the ligamentum subcruentum (arrowhead).
not tear (b) Corresponding low-power photomicrograph (azan stain) shows collagen fibers with vascular connective
tissue (arrows). Demineralized bone appears dark red, hyaline cartilage appears medium blue, and collagen fibers
with vascular connective tissue appear as heterogeneous regions of mixed light blue and white.

15. Elbow
Although is not an articulation often evaluated by MRI, such as shoulder
and knee, the elbow can present pitfalls and is essential that radiologists
be aware to not make mistakes.
Pseudodefect of the capitellum
Pseudodefect of the capitellum is one of the most frequently pitfall found
in elbow, usually seen in coronal and sagittal images, and should not be
confused with osteochondral lesion.
Two osteochondral diseases are described in capitellum: osteochondritis
dissecans and Panner's disease.
Panner's disease generally affects younger patients, around 5-10 years,
and tends to involve the whole capitellum. Osteochondritis dissecans
occurs in patients in adolescence, involvement of the capitellum is often
partial and tends to form loose bodies.
However, the osteochondral lesion occurs on the anterior aspect of the
capitellum while pseudo-defect affects the posterolateral aspect and there
is no marrow edema. The presence of synovial fluid or contrast makes
easier to recognize this pseudodefect.

16. Trochlear pseudodefect
Trochlear pseudodefect is a bare area devoid of cartilage localized in the trochlear
notch. It is usually has a small size, measuring up to 7 mm in width.
The lesion appears as a slight interruption of cortical bone in sagittal images and
like the pseudo-defect of the capitellum should not be confused with
osteochondral injury. The absence of edema confirms it is a normal find.
It is important to report that trochlear pseudodefect can be a place for loose
bodies’ deposit.
Transverse trochlear ridge:
Transverse trochlear ridge is detected as central elevation in the trochlear groove
on sagittal images and was detected by Rosenberg and colleagues in 68% of the
ulnar bones inspected.
It is usually very small, up to 3 mm high, but in a few case can be prominent and
simulate an osteophyte.
Triceps tendon: striations and insertion
The triceps tendon is formed by a small surface layer and another layer deeper
and thicker, which combine to insert on the posterior aspect of the olecranon.
At the triceps tendon insertion high signal can be detected and should not be
confused with tear or degeneration. This high signal occurs by the presence of
fibro-fatty tissue between the tendon fibers.

17. Sagittal and coronal proton-density fast spin-echo (TR 2300 ms, TE 35
ms) demonstrate the pseudodefect of the capitellum (white arrows).

18. (c) Coronal and (d) sagittal T2-weighted images of the elbow in a 53-year-old
woman with lateral epicondylosis. Images demonstrate subcortical cystic
change (arrow) along the posterior portion of the capitellum, compatible
with a pseudodefect, not to be mistaken for an osteochondral lesion.

19. Pseudodefect of the capitellum.

20. Pseudodefect of the capitellum.

21. Pseudo-loose body

22. Plica: This structure on the lateral side of the joint is sometimes seen and is a plica.
It can be prominent and almost look like a meniscus. It is a normal structure, but
sometimes it is thickened or irregular and it may be a cause of symptoms.

23. Coronal proton-density fast spin-echo and T1 weight images: normal triceps tendon striations.

24. Sagittal proton-density fast spin-echo (TR 2300 ms, TE 35 ms) image of the elbow showing
cortical interruption (white arrow): trochlear pseudodefect. There is no marrow edema.

25. Thank You.