This in vitro study attempted to correlate magnetic resonance (MR) signal intensity with concentration of albumin solution in magnetic field strength of 2.0 tesla (T) and 0.5T. MR Imaging of bovine serum albumin solutions of various concentrations ranging from 0 to 40g/㎗ was performed on both 2.0T and 0.5T MR units. The relative (with respect to normal saline) signal intensities of each albumin solution were measured in T-1weighted, proton on each pulse sequence, and compared between 2.0T and 0.5T. Additionally, the albumin concentrations showing signal intensities identical to those of white mater, cortical gray matter and cerebrospinal fluid(CSF) of normal brain MRI were determined by visual comparison of those images. 1. On T1-weighted (SE 400-500 msec/30 msec) images under 2.0T and 0.5T field strengh, the signal intensity increased with increasing albumin concentrations up to about 30-35 g/㎗ and then decreased. For the solutions ranging from 0 to about 5 g/㎗ concentrati n, the signal intensities appeared isointense to normal saline on visual inspection. 2. On proton density-weighted (SE 2000-255 msec/30 msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations upto about 7.5-10g/㎗, and then gradually deceased. 3. On T-2 weighted (SE 2000-2500 msec/80-100msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations upto about 7.5-10g/㎗, and then gradually decreased. Above the concentration of about 25-30g/㎗, the signal intensity appeared lover than that of normal saline on visual inspection. 4. compared with the signal intensities of normal brain structures on T-1 weighted images under 2.0T and 0.5T field strength, the signal intensities of the albumin solution below 2.5-5g/㎗ concentration were similar to that of CSF, and those of about 5-15 g/㎗ concentration and about 15-25 g/㎗ corresponded to cortical gray m tter and periventricular white matter, respectively. On proton density-weighted images, the signal intensities of CSF, cortical gray matter and white matter were all similar and corresponded to albumin concentrations of 0 to 2.5-5.0 g/㎗ and above 30-35 g/㎗ concentration. The solution ranging from 5-.5 v to 25.-30 g/㎗ concentration showed higher signal intensities than brain parenchyma. On T-2 weighted images, the signal intensities of the solutions of 0 to 25-30 g/㎗ concentration appeared identical to that of CSF, and those of higher concentration were similar to those of brain parenchyma. 5. Any difference in signal intensity between 2.0T and 0.5 T could not be recognized by visual comparison, although the signal intensities with 0.5T were generally slightly higher o T-1 weight images and slightly lower in proton density-and T2-weighted images. In conclusion, since albumin solution shows variable MR signal intensities, depending on its concentration, and especially shows low sig al intensity at the concentration above about 35 g/㎗ on T1-weighted images, even pure proteinaceous cysts are supposed to have ver variable signal intensities in clinical MR images.