DYNAMIC GD-DTPA ENHANCED MRI MEASUREMENT OF TISSUE CELL-VOLUME FRACTION

Citation
Km. Donahue et al., DYNAMIC GD-DTPA ENHANCED MRI MEASUREMENT OF TISSUE CELL-VOLUME FRACTION, Magnetic resonance in medicine, 34(3), 1995, pp. 423-432
Citations number
60
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging
ISSN journal
07403194
Volume
34
Issue
3
Year of publication
1995
Pages
423 - 432
Database
ISI
SICI code
0740-3194(1995)34:3<423:DGEMMO>2.0.ZU;2-G
Abstract
A new technique for measuring tissue cellular volume fraction, based o n an improved modeling of the dynamic distribution of Gd-DTPA and the effect of proton exchange, is described, This technique uses peak T-1 enhancement and blood Gd-DTPA concentration to compute tissue cellular volume fraction, The feasibility of this technique is demonstrated wi th computer simulations that explore the limits of the simplifying ass umptions (small vascular space, slow vascular-extravascular proton exc hange), and by direct comparison of MR and radionuclide cell fraction measurements made in muscle, liver, and tumor tissue in a rat model, T he computer simulations demonstrate that with slow to intermediate vas cular proton exchange and vascular fractions less than 10% the error i n our cell fraction measurements typically remains less than 10%, Cons istent with this prediction, a direct comparison between MR and radion uclide measurements of cell fraction demonstrates mean percent differe nces of less than 10%: 1.9% in muscle (n = 4); 9% in liver (n = 1) and 9.5% in tumor (n = 4), Similarly, for all rats studied, the MR-measur ed cell fractions (muscle (0.92 +/- 0.04, n = 20); liver (0.76 +/- 0.1 1, n = 9); whole tumor (0.69 +/- 0.15, n = 22)) agree with the cell fr action values reported in the literature, In general, the authors' res ults demonstrate the feasibility of a simple method for measuring tiss ue cell fraction that is robust across a broad range of vascular volum e, flow, and exchange conditions, Consequently, this method may prove to be an important means for evaluating the response of tumors to ther apy, Key words: Cell fraction; Gd-DTPA; proton exchange.