CT and MR Imaging of Extrahepatic Fatty Masses of the Abdomen and Pelvis: Techniques, Diagnosis, Differential Diagnosis, and Pitfalls

Abstract

The differential diagnosis of extrahepatic abdominopelvic masses is wide. Demonstration of fat within a lesion at noninvasive imaging is an important clue for narrowing the differential diagnosis. Macroscopic fat is readily identified with both computed tomography (CT) and magnetic resonance (MR) imaging. Demonstration of microscopic fat is more difficult and may require special techniques. Identification of fat with CT is based on x-ray resorption and therefore on the attenuation (typically less than -20 HU). Several MR imaging techniques have been developed for fat suppression. Two of the most widely available are spectroscopic fat saturation and chemical shift (in-phase/opposed-phase) imaging. Entities with predominantly macroscopic fat include myelolipoma, angiomyolipoma, teratoma, liposarcoma, lipoma, epiploic appendagitis, omental infarction, and mesenteric panniculitis. Lesions with predominantly microscopic fat include adrenal adenoma and some teratomas. Other fat-containing entities involve the mesentery and bowel wall; these include fibrofatty mesenteric proliferation and submucosal fat deposition.

CT and MRI Imaging Diagnosis of Epidural Idiopathic Sterile Pyogranulomatous Inflammation in a Dog Spinal Canal

“…Moreover, because fat suppression techniques are useful in ascertaining the fatty characteristics of a mass [2,[4][5][6], the mass lesion in the present case was exactly defined by a fat suppression technique. Differential diagnoses for an MR image like that in the present case in which T1-and T2-weighted images showed hyperintense signals include hemorrhage, hematoma, and fatty tissue [1,[3][4][5][6]8]. Of these, a fat suppression image may be useful to distinguish the involvement of adipose tissue amongst other possible etiologies [2,[4][5][6].…”

Torsion of a preperitoneal pedunculated lipoma of anterior abdominal wall mimicking acute appendicitis

“…[10,11] Ancak deneyimli ellerde ultrasonografi de yüksek tanısal değere sahiptir. Ultrasonografik olarak lipomlar ekojenik kapsülle çevrili izo-hiperekoik lezyonlar olup, çevre dokuları penetre etmeyen, yumuşak ve mobil kitleler olarak saptanırlar.…”

Mielolipoma adrenal bilateral em um cão

“…Quase sempre o mielolipoma de adrenal se constitui em um achado incidental de necropsia, tanto em humanos quanto em animais (LAM & LO, 2001;RÉPÁSSY et al, 2001;NAKAJO et al, 2003;MANASSERO et al, 2004 computadorizada e ressonância magnética (OTAL et al, 1999;NAKAJO et al, 2003;ELSAYES et al, 2004;PEREIRA et al, 2005). Essas técnicas também são utilizadas em clínica médica veterinária, entretanto, bem menos disponíveis em muitos locais (LATIMER & RAKICH, 1995;MYERS, 1997).…”

“…Os neoplasmas benignos primários da adrenal incluem adenoma adrenocortical, feocromocitoma e teratoma; tumores malignos incluem carcinoma cortical e lipossarcoma (LATIMER & RAKICH, 1995;RÉPÁSSY et al, 2001;NAKAJO et al, 2003;PEREIRA et al, 2005). Em humanos, os neoplasmas metastáticos adrenais são os mais freqüentes, especialmente carcinomas pulmonares e mamários.…”

“…Histologicamente deve-se diferenciar mielolipoma de eritropoese extramedular (NEWMAN et al, 2000;MANASSERO et al, 2004;PEREIRA et al, 2005). O adenoma adrenocortical é parcial ou completamente encapsulado e constituído por células bem diferenciadas, semelhantes às células secretoras das zonas fasciculada e reticulada (CAPEN, 2002).…”