Sang Ok Park MD, Presenter: Nothing to Disclose

Jeong Kon Kim MD, Abstract Co-Author: Nothing to Disclose

Kyoung Ah Kim, Abstract Co-Author: Nothing to Disclose

Namkug Kim MS, Abstract Co-Author: Nothing to Disclose

Bum-Woo Park, Abstract Co-Author: Nothing to Disclose

Kyoung-Sik Cho MD, Abstract Co-Author: Nothing to Disclose

To verify the usefulness of relative apparent-diffusion-coefficient (rADC) and to determine the reference organ for calculating rADC.

Fifty-five patients with uterine cervix cancer and diffusion-weighted MR (b value, 0 and 1000) on 1.5 T unit, were enrolled. Two radiologists measured ADC values at three points in each of various organs, including the spleen, liver, right kidney, lumbar spine, spinal cord, and right gluteus muscle. Reliability for measuring ADC in organs was evaluated by coefficient-of-variation (CV). rADC was calculated by the follows: rADC = ADC of lesion/ADC of reference organ. ADC and rADC were measured in uterine cervix cancer and adjacent endometrium. ROC analysis was used for comparing the performance of ADC and rADC in differentiating cancer tissue from endometrium.

The mean CV in two radiologists was lower in right kidney (6.2% and 4.7%) than in the other organs (spleen, 11.6% and 7.5%; liver, 15.7% and 15.4%; lumbar spine, 16.8% and 14.0%; spinal cord, 11.3% and 11.2%; and right gluteus muscle, 16.2% and 18.4%). ADC and rADC were 1.012 ± 0.171 and 0.525 ± 0.070 in cancer tissue and 1.328 ± 0.275 and 0.687 ± 0.112 in endometrium, respectively, The area under ROC for differentiating cervix cancer from endometrium was greater in rADC (0.919) than in ADC (0.847) (P = .009).

rADC is superior to ADC in differentiating cancer tissue from adjacent non-cancerous tissue and the right kidney is adequate for the reference organ for calculating rADC.

The rADC, a normalized form of ADC, can reduce individual variation of ADC, and the right kidney is the optimal internal organ for the reference ADC of rADC.

Park, S, Kim, J, Kim, K, Kim, N, Park, B, Cho, K, Relative Apparent Diffusion Coefficient: Verification of Its Usefulness and Determination of Reference Organ.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014889.html