Semiautomated ROI Analysis in Dynamic MR Studies. Part II

Evaluation of glomerular function in individual kidneys using dynamic magnetic resonance imaging

“…We therefore manually drew the ROIs over the cortex and medulla in each serial imaging plane and developed time-dependent signal intensity curves. von Schulthess et al [9] performed semiautomated ROI analysis, in which the signal intensities of the local regions in each frame were used to compute statistics and to generate curves representing local temporal signal intensity changes due to contrast agent excretion, using a multistage processing scheme applied to correct the displacement of the kidneys within the time series.…”

“…Renal function has traditionally been evaluated by nuclear medicine clearance or radiographic techniques. Since the advent of fast pulse sequences and water-soluble contrast agent, it has become possible to examine renal function by dynamic MR imaging [6][7][8][9]. Gadoliniumdiethylenetriamine pentaacetic acid (Gd-DTPA), a paramagnetic contrast agent, is freely filtered at the glomerulus and is not secreted or reabsorbed by the renal tubules.…”

MR renography: An algorithm for calculation and correction of cortical volume averaging in medullary renographs

“…The MRR is an alternative to the functional radionuclide renograph with potential advantages. The superior spatial resolution of the MR image allows cortical and medullary structures to be functionally separated, a feature that is not possible with scintigraphic techniques (1)(2)(3)(4)(5)(6). Separate and combined analysis of cortical and medullary signal curves may be of future importance in the differentiation of kidney disease (1,4,(7)(8)(9)(10)(11)(12).…”

“…In various reports on dynamic MR of the kidney, functional information is obtained by selectively placing regions of interest (ROIs) over cortical and medullary tissue and estimating time-dependent changes in signal over these areas (1)(2)(3)(4)(5)(6)(7)(8)(9)11,12,16). The cortical ROI is placed over the peripheral cortex beneath the renal surface.…”

“…A frequently encountered problem in patients with decreased renal perfusion or parenchymal disease is suboptimal contrast between cortex and medulla (5,16). In these cases, the conditions necessary for adequate medullary ROI placement are lacking.…”