Dynamic Gd-DTPA-Enhanced MR imaging of the kidney: Comparison between T1- and T2(*)-weighted sequences

Objective: To determine whether T1- or T2*-weighted sequences are more informative and practical in dynamic Gd-DTPA-enhanced MR imaging for the evaluation of renal blood flow and function. Materials and Methods: Dynamic Gd-DTPA-enhanced MR imaging of the kidney was performed in 7 patients by either T1-weighted TurboFLBSH (TR/TE/TI/FA = 9/4/27/8) or T2*-weighted FLASH (TR/TE/FA = 32/22/10) sequences for comparison of the enhancement pattern. None of the subjects had a suspicion of renal dysfunction from laboratory data, and the absence of renal artery stenosis was confirmed by conventional angiography. Results: During the early phase, the marked signal increase in T1-weighted imaging in the renal cortex corresponded to a similar marked decrease in signal intensity in T2*-weighted imaging. During the middle and late phases, the medulla was dramatically decreased in intensity on the T2*-weighted imaging resulting in a good contrast between the cortex and medulla. Conclusion: Both sequences may provide almost similar information about the renal cortical blood flow. However, T2*-weighted dynamic MR imaging may be more informative than T1-weighted dynamic MR imaging about the concentrating ability in the renal medulla. A high concentration of Gd-DTPA in the tubular structure was suspected to cause a dramatic decrease in intensity in the medulla in T2*-weighted imaging.