Henry Knipe

Featured in:

Articles

Specific absorption rate

2 months ago | radiopaedia.org | David Chang |Henry Knipe

The specific absorption rate (SAR) is the rate at which radiofrequency (RF) energy is absorbed by tissues during MR image acquisition, which is measured in watts per kilogram (W/kg) 4. It is used as indirect measure of RF heating, which is an MRI safety concern 4. TechniqueThe International Electrotechnical Commission (IEC) and the USA's Food and Drug Administration (FDA) limit the amount of energy absorbed by the body for a single MRI examination to 1°C/kg 1,2.
Marie Skłodowska Curie

2 months ago | radiopaedia.org | Andrew Murphy |Henry Knipe |Frank Gaillard

Marie Skłodowska Curie (1867-1934), commonly known as Marie Curie and Madame Curie 5, was a Polish-born French scientist known for her pioneering radioactivity work. Much of her early work was in collaboration with her husband, Pierre Curie (1859-1906). Her work shaped medicine, warfare, and scientific research for countless generations, earning her Nobel prizes in physics and chemistry 1,3.
Lateral collateral ligament injury of the knee

2 months ago | radiopaedia.org | Joachim Feger |Henry Knipe

Lateral collateral ligament injuries of the knee are rare in isolation and usually occur in the context of a posterolateral corner injury or in association with other ligamentous or meniscal injuries. A lateral collateral ligament injury of the knee is also referred to as the fibular collateral ligament injury and comprises a spectrum of injuries ranging from ‘sprain’ over ‘tear’ to ‘rupture’.
Acromioclavicular joint cyst

2 months ago | radiopaedia.org | Matt Morgan |Henry Knipe

Acromioclavicular (AC) joint cysts form as a supraclavicular fluid collection due to the flow of synovial fluid from the glenohumeral joint across the AC joint - the geyser sign is commonly used to describe this phenomenon. They are associated with chronic rotator cuff tears and degenerative AC joints. AC joint cysts may present as a pseudotumor above the acromioclavicular joint 5, which is classically described as slow-growing.
Uterine arteriovenous malformation

2 months ago | radiopaedia.org | Henry Knipe

Uterine arteriovenous malformations (AVMs) result from the formation of multiple arteriovenous fistulous communications within the uterus without an intervening capillary network. Somewhat confusingly, the term “uterine arteriovenous malformation” has been used interchangeably with “enhanced myometrial vascularity” in the literature. The terms have been used to describe the sonographic appearance of a hypervascular lesion within the uterine myometrium that demonstrates turbulent flow.
Demise of a twin

Jan 8, 2025 | radiopaedia.org | Henry Knipe

Demise of a twin is a complication that can occur in a twin pregnancy (particularly monochorionic pregnancies) and may be due to a wide range of conditions. Once the twin dies, most of the dead twin tends to be absorbed, leaving behind a small flattened remnant known as the fetus papyraceus. The incidence of intrauterine death of a single twin is ~6.5% (range 6-7%) 1-2.
Approach article structure

Jan 8, 2025 | radiopaedia.org | Joachim Feger |Henry Knipe

Approach articles are a special article type focused on a specific imaging investigation or condition in which a test or specific imaging protocol is applied. Approach articles will only be accepted if created by professionals with substantial subject expertise (largely limited to senior subspecialty radiologists), and their acceptance is at the discretion of the editor-in-chief. Experience with editing Radiopaedia articles and familiarity with our style guide is mandatory.
Anterior cruciate ligament avulsion fracture

Dec 9, 2024 | radiopaedia.org | Yuranga Weerakkody |Henry Knipe

Anterior cruciate ligament (ACL) avulsion fractures,also known as tibial eminence avulsion fractures, are a type of knee avulsion fracture. They typically involve separation of the tibial attachment of the ACL to variable degrees, although separation at the femoral attachment is rare 5. This injury is more common in children aged 8-14 years than in adults.
Patellar tilt angle

Dec 5, 2024 | radiopaedia.org | Yuranga Weerakkody |Henry Knipe

The patellar tilt angle is a widely used measurement to determine patellar tilt and can be used in the assessment of anterior knee pain 1-2. The patellar tilt angle can be evaluated on axial images showing the maximum cross-sectional area of the patella 5. It is measures as the angle between the posterior condylar line and a second line between the lateral edge of the lateral patellar facet and the medial edge of the medial patellar facet 4-6.
Postoperative assessment after thyroid cancer surgery

Dec 1, 2024 | radiopaedia.org | Matt Morgan |Henry Knipe

Postoperative assessment after thyroid cancer surgery is performed in the surgical bed and regional lymph nodes, looking for possible recurrence of disease.