Table 1.
CT and MRI features of angiomyolipomas
| Types of AMLs | CT | MRI | ||
| Classic | UE: | Fat attenuation (<–10 HU) | FS: | Signal drop |
| No calcification | CS: | India-ink artefact at macroscopic fat-water interfaces | ||
| CE: | ± Intratumoral aneurysm | T2W: | Hyperintense area corresponding with signal drop out on fat-suppression image secondary to macroscopic fat | |
| Hyperattenuating fat-poor | UE: | Hyperdense (usually > 45 HU) | FS: | No signal drop |
| No fat attenuation | CS: | No signal drop | ||
| No calcification | T2W: | Homogeneous hypointense | ||
| No cystic/Necrotic change | ||||
| CE: | Variable, frequently homogeneous early enhancement with subsequent washout | |||
| Isoattenuating fat-poor | UE: | Isodense (between –10 HU and 45 HU) | FS: | No signal drop |
| No fat attenuation | CS: | Signal drop on OP compared with IP | ||
| No calcification | T2W: | Hypointense | ||
| No cystic/necrotic change | ||||
| CE: | Variable, ± gradually progressive enhancement | |||
| AML with epithelial cyst | UE: | Solid part; hyperdense (usually > 45 HU) | FS: | No signal drop |
| Cystic part; isodensity | CS: | Solid part; ± signal drop on OP compared with IP. | ||
| CE: | Solid part; ± homogeneous early enhancement with subsequent washout | T2W: | Solid part; Hypointense | |
| Cystic part; ± multiloculated, no enhancement | Cystic part; Bright signal | |||
| Epithelioid | UE: | ± Fat attenuation | FS: | ± Signal drop |
| ± Calcification | CS: | ± Signal drop on OP compared with IP. | ||
| ± Internal haemorrhage, Necrosis | T2W: | Heterogeneous hypointense | ||
| CE: | Heterogeneous | ± Hyperintense from necrosis | ||
| Variable enhancement | ||||
| Presence of vascular invasion | ||||
| Presence of metastasis | ||||
AML, angiomyolipoma; CE, contrast enhanced CT; CS, chemical shift MR image; FS, fat suppression MR image; HU, Hounsfield unit; IP, in phase image; OP, opposed phase image; T2W, T2 weighted MR image; UE, unenhanced CT.