The Carpal Tunnel View

The carpal tunnel view is obtained by hyperextending the wrist and shooting 20-30 degrees tangent to the long axis of the hand.

References

Meschan, I (1975). An Atlas of Anatomy Basic to Radiology. Philadelphia, PA: W.B. Saunders Company.

Plicae Palmatae

The plicae palmatae (Latin for leaf-shaped fold) is a normal cervical structure that is commonly seen on routine MRI of the normal uterus. It is seen in about 50% of women between 20-50, about 25% in women in their 50s.

The median ridge of the plicae palmatae appears on T2-weighted images as a longitudinal ridge of low signal at the midline of the anterior and/or posterior wall that protrudes into the cervical canal. The lateral ridges are typically not seen on MRI, as they branch upward and laterally and upward along the cervical wall.

It can be mistaken for an anomalous uterine septum.

References

Takahata A, Koyama T, Kido A, Kataoka M, Umeoka S, Nishizawa S, Nishimura T, Togashi K. The frequency of the plicae palmatae in the uterine cervix on MR imaging. Abdom Imaging. 2009 Mar-Apr;34(2):277-9.

Bridging Vessel Sign

Bridging vessel sign, also known as the bridging vascular sign, refers to the appearance of multiple vessels between the uterus and a pelvic mass adjacent to the uterus. The sign helps differentiate an exophytic uterine mass (e.g., a subserosal fibroid) from a pelvic mass adjacent to the uterus.

Color or power Doppler ultrasound show the vessels. On MRI, the vessels appear as curvilinear tortuous flow voids.

References

Madan R. The bridging vascular sign. Radiology. 2006 Jan;238(1):371-2.

Lunula

The lunula (also known as a persisting center of the ulnar styloid and (I think) os ulnostyloideum) is an ossification center within the fibrocartilaginous structure between the triangular fibrocartilage, triquetrum, and the base of the fifth metacarpal. It is found distal to the ulnar styloid between the triangular fibrocartilage and the triquetrum.

It may fuse to ulnar styloid and give it an unusual and long appearance. It may also be difficult to distinguish from an old ulnar styloid avulsion (which may be the case in the image shown).

The lunula is a common finding in non-human primates.

References

Timins ME. Osseous anatomic variants of the wrist: findings on MR imaging. AJR Am J Roentgenol. 1999 Aug;173(2):339-44.

Bicondylar Intraarticular Humeral Fracture

Bicondylar intraarticular fractures (also known as bicolumn fractures) of the distal humerus make up only 1% of distal humerus.

Distal humeral fractures are classified into three broad categories by the Müller Arbeitsgemeinschaft für Osteosynthesefragen (AO) system. Each category is further divided into 3 subcategories, and each into 3 sub-subcategories, giving a total of 27 types!

• Type A: Extra-articular - No involvement of displaced fractures extending into the articular surface
• Type B: Partial intra-articular - Part of the articular component is involved, leaving the other part attached to the metaphysis or diaphysis
• Type C: Complete intra-articular - Articular surface is involved and the metaphyseal fracture completely separates the articular component from the diaphysis.
  • C1: Articular simple, metaphyseal simple
    • C1.1: Slight displacement
    • C1.2: Marked displacement
    • C1.3: T-shaped epiphyseal
  • C2: Articular simple, metaphyseal multifragmentary
    • C2.1: With an intact wedge
    • C2.2: With a fragmented wedge
    • C2.3: Complex
  • C3: Articular multifragmentary
    • C3.1: Metaphyseal simple
    • C3.2: Metaphyseal wedge
    • C3.3: Metaphyseal complex (current case)

Our case is a type C3.3 fracture. There are two fracture planes through the articular surface (better seen on CT), making this an articular multifragmentary fracture (C3). Multiple metaphyseal fragments are seen, making this a metaphyseal-complex fracture.

The full range of fractures can be found at the OA web site (see below). Another classification scheme, the Jupiter system, is also used.

References

OA Classification

Hemangiopericytoma (Central Nervous System)

Hemangiopericytomas are hyperattenuating extra-axial lesions with dural attachments that may mimic meningiomas. Unlike meningiomas, however, they do not demonstrate calcifications or hyperostosis and often have a heterogeneous enhancement. Meningiomas also demonstrate broad-based dural attachment and are typically round. Hemangiopericytomas, on the other hand, have narrow bases of attachment and are usually lobulated.

Unlike meningiomas, which displace vessels, hemangiopericytomas demonstrate internal flow voids. The angiographic pattern is also different. As opposed to the spoke-wheel pattern of vessels, the vessels in hemangiopericytomas are irregularly arranged.

Differential considerations include:

• Meningioma
• Dural metastases
• Lymphoma
• Neurosarcoidosis
• Gliosarcoma

More recently, the concept of hemangiopericytoma as a distinct entity has come into question, with the majority of these tumors now classified as solitary fibrous tumors.

References

• Gengler C, Guillou L. Solitary fibrous tumour and haemangiopericytoma: evolution of a concept. Histopathology. 2006 Jan;48(1):63-74.
• Salzman KL. Hemangiopericytoma. StatDx. Updated 2008-06-02.

Cleidocranial Dysplasia

Cleidocranial dysplasia is a generalized skeletal dysplasia that was originally thought to affect only the skull and clavicles. It is characterized by:

• Clavicle: Incomplete ossification, ranging from absence to hypoplasia
• Skull: Wormian bones, enlarged calvaria, frontal bossing, and open fontanelles
• Chest: Bell-shaped thorax
• Hand: Brachydactyly with hypoplastic distal phalanges
• Pelvis: Pelvic hypoplasia, widened pubic symphysis, coxa vara
• Teeth: Supernumerary teeth and severe dental anomalies

References

Mundlos S. Cleidocranial dysplasia: clinical and molecular genetics. J Med Genet. 1999 Mar;36(3):177-82.