Imaging spectrum of abnormal subcutaneous and visceral fat distribution

Abstract

Adipose tissue plays multiple and complex roles not only in mechanical cushioning and energy storage but also as an important secretory organ that regulates energy balance and homeostasis multilaterally. Fat tissue is categorized into subcutaneous fat tissue (SCAT) or visceral fat tissue (VSA) depending on its distribution, with the two having different metabolic functions. Near-total lack of fat in congenital/acquired generalized lipodystrophy, cachexia, or any other severe malnutrition condition induces severe multi-organ dysfunction due to lack of production of leptin and other adipokines. Increased visceral fat tissue secondary to obesity, hypercortisolism, or multiple symmetric lipomatosis raises the risk of insulin resistance, cardiac complications, and airway or spinal canal stenosis, although the fat distribution pattern differs in each condition. Partial abnormal fat distribution conditions such as HIV/HAART therapy-associated lipodystrophy, familial partial lipodystrophies, and acquired partial lipodystrophy frequently show a mixture of lipoatrophy and lipohypertrophy with metabolic dysfunction. Characteristic imaging features in conditions with local abnormal fat distribution can provide information about a patient's co-existent/unrecognized disease(s), past medical history, or lifestyle. Knowledge of characteristic abnormal fat distribution patterns can contribute to proper and timely therapeutic decision-making and patient education.

Rapid Depletion of Subcutaneous Adipose Tissue during Sorafenib Treatment Predicts Poor Survival in Patients with Hepatocellular Carcinoma

“…The definite reason SAT alone rapidly decreased just after introducing sorafenib in advance of skeletal muscle and VAT remains unclear. SAT is known to act as metabolic storage that can accumulate superfluous energy [ 24 ]. Therefore, we consider that SAT might first be used as an energy source when a negative energy balance is induced by sorafenib.…”

Mass-Like Fat at the Medial Midfoot: A Common Pseudolesion

“…In some cases, however, it may be difficult to determine whether a lipoma is present at a location of symptoms. 19 …”

“…In some cases, however, it may be difficult to determine whether a lipoma is present at a location of symptoms. 19 Imaging characterization of any potential mass requires documentation of additional secondary features such as location, displacement or invasion of adjacent structures, and reaction of surrounding tissues. Correlation for pain or a palpable mass is also clinically important when the imaging features are worrisome.…”

Pseudo fat-saturated appearance of magnetic resonance head and neck images in 2 cachectic patients

“…This is in accordance with other medical conditions that are characterized by generalized abnormal fat distribution, such as eating disorders. For example, Yamamoto et al showed diminished subcutaneous fat and diffuse T1 hypointense marrow signal in an individual with bulimia nervosa [5] . Kraeft et al reported that individuals with severe anorexia nervosa demonstrate loss of fat signal in both bone marrow and subcutaneous tissues on MRI [6] .…”

“…3 ). Residual subcutaneous and visceral fat were found in classic locations of brown adipose tissue (axilla, supra- and infraclavicular fossa, around solid organs) and demonstrated increased density, which is thought to reflect smaller fat cell size with inflammatory/edematous change during lipolysis [5] . This patient declined treatment and died 2 months later with palliative measures.…”