Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

21 results found
Article

Z deformity

The Z deformity is one of the musculoskeletal manifestation of rheumatoid arthritis in hand: radial deviation at the wrist ulnar deviation of the digits, and often palmar subluxation of the proximal phalanges
Article

Z-score

Z-scores are a way to translate individual data points into terms of a standard deviation.  Z = (X - Xbar) / σ X: individual data point Xbar: the arithmetic mean σ: the standard deviation The purpose of the Z-score is to allow comparison between values in different normal distributions. Two...
Article

Zabramski classification of cerebral cavernous malformations

The Zabramski classification of cerebral cavernomas has been proposed as a way of classifying cerebral cavernous malformations, and although not used in clinical practice it is useful in scientific publications that seek to study cavernous malformations. The classification was proposed in 1994 ...
Article

Zebra spleen

Zebra spleen refers to a transient heterogeneous enhancement of the spleen parenchyma during the arterial phase of contrast enhancement CT, MRI, or ultrasound imaging. This is due to different blood flow velocity in different splenic blood pathways. Heterogeneity of splenic parenchyma manifested...
Article

Zebra stripe sign

The zebra stripe sign occurs where children with osteogenesis imperfecta have been treated with cyclical bisphosphonate therapy, e.g. pamidronate. When the drug is delivered in cycles, dense bone is formed while treatment is being given. This results in dense stripes across the metaphyses of bon...
Article

Zebra stripes

Zebra stripes/artifacts appear as alternating bright and dark bands in a MRI image. The term has been used to describe several different kind of artifacts causing some confusion. Artifacts that have been described as a zebra artifact include the following: Moire fringes 1,2 Zero-fill artifact...
Article

Zellweger syndrome

Zellweger syndrome (ZS), also known as the cerebrohepatorenal syndrome, is a multisystem metabolic abnormality. As the name implies it primarily affects the central nervous system (CNS), liver and kidneys.  Epidemiology The condition typically presents in neonates with poor feeding and/or seiz...
Article

Zenker diverticulum

Zenker diverticulum, also known as a pharyngeal pouch, is an outpouching at the level of the hypopharynx, just proximal to the upper oesophageal sphincter. It is located in the posterior midline at the cleavage plane between the thyropharyngeus muscle and the cricopharyngeus muscle (known as the...
Article

Zero fill artifact

Zero fill artifact is one of many MRI artifacts and is due to data in the K-space array missing or set to zero during scanning. The abrupt change from signal to no signal results in artifacts in the images showing alternating bands of shading and darkness, often in an oblique direction. A spike...
Article

Zero filling interpolation

Zero filling interpolation (ZIP) is the substitution of zeroes for unmeasured data points in order to increase the matrix size of the new data prior to Fourier transformation of MR data. This results in pixels smaller than the actual resolution of the image. The zero filling occurs in the periph...
Article

Zimmerman-Laband syndrome

Zimmerman-Laband syndrome is a rare congenital syndrome, characterized primarily by gingival hypertrophy and skeletal abnormalities.  Pathology The molecular basis of the syndrome is currently unknown. An autosomal dominant mutation with high mutation rate and rare instances of germinal mosaic...
Article

Zinner syndrome

Zinner syndrome is a triad of Wolffian duct anomalies comprising of unilateral renal agenesis, ipsilateral seminal vesicle cyst, and ejaculatory duct obstruction 1. Clinical presentation Patients are typically diagnosed at 3rd or 4th decade of life and often present with perineal pain, recurre...
Article

Zipper artifact

In MR imaging, zipper artifact refers to a type of MRI artefact where one or more spurious bands of electronic noise extend perpendicular to the frequency encode direction and is present in all images of a series.         There are various causes for zipper artifacts in images. Most of them are...
Article

Zollinger-Ellison syndrome

Zollinger-Ellison syndrome (ZES) is a clinical syndrome that occurs secondary to a gastrinoma.  Clinical presentation Diagnosis of ZES is often delayed by 5-7 years after the onset of symptoms 2.  Pathology Gastrinomas are usually multiple and typically located in the duodenum (more common) ...
Article

Zona orbicularis

The zona orbicularis are circular fibres of the hip joint capsule and form a collar around the femoral neck. Though partly blended with the pubofemoral and ischiofemoral ligaments, these fibres are not directly attached to bone. 
Article

Zuckerkandl tubercle

Zuckerkandl tubercle is a normal variant of the thyroid. It may be mistaken for a thyroid nodule or mass or lymph node.  Zuckerandl tubercle is a projection of normal thyroid tissue from the posterior aspect of the lateral lobes of the thyroid gland.  It is also an important surgical landmark ...
Article

Zuelzer-Wilson syndrome

The Zuelzer-Wilson syndrome (total colonic aganglionosis) is a subset of Hirschsprung disease, in which the whole colon is aganglionic. It is uncommon and accounts for 2-13% of cases of Hirschsprung disease 3. Multiple procedures have been devised to treat the condition, including proctocolectom...
Article

Zygoma

The zygoma (or zygomatic bone) is an important roughly quadrangular paired facial bone which forms the cheek prominences. Gross anatomy Zygoma has three surfaces: lateral or antero-lateral surface is convex and pierced at its orbital border by the zygomaticofacial foramen which houses the zyg...
Article

Zygomatic arch

The zygomatic arch is formed by the union of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone at the zygomaticotemporal suture.  Related pathology Le Fort type 3 fracture zygomaticomaxillary complex fracture
Article

Zygomaticomaxillary complex fracture

Zygomaticomaxillary complex (ZMC) fractures, also known as a tripod, tetrapod, quadripod, malar or trimalar fractures, are seen in the setting of traumatic injury to the face. They comprise fractures of the: zygomatic arch inferior orbital rim, and anterior and posterior maxillary sinus walls ...
Article

Zygomaticomaxillary suture

The zygomaticomaxillary suture exists between the maxillary margin of the zygomatic bone and the zygomatic process of the maxilla.

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