Een Young Cho MD, Presenter: Nothing to Disclose

Seung Ho Kim MD, Abstract Co-Author: Nothing to Disclose

Jung Hee Yoon MD, Abstract Co-Author: Nothing to Disclose

Yun-Jung Lim, Abstract Co-Author: Nothing to Disclose

Yedaun Lee MD, Abstract Co-Author: Nothing to Disclose

Choong Ki Eun MD, Abstract Co-Author: Nothing to Disclose

To identify the morphologic features of metastatic and non-metastatic lymph nodes (LNs) on diffusion-weighted imaging (DWI) and to evaluate the added value of the morphologic features for evaluating LNs in patients with primary rectal cancer.

Institutional review board approved this retrospective study and waived informed consent. Forty-four consecutive patients (17 men, 27 women; mean age: 63 years, range: 37–82 years) with primary rectal cancer who underwent surgery, were enrolled in this study. All patients underwent 1.5-T rectal MRI with DWI (b=0, 1000). To identify morphologic features on DWI, two blinded radiologists in consensus categorized each LN into the several groups according to the imaging characteristics (border, shape and signal intensity). By Fisher’s exact test, the morphologic features were determined. To evaluate the added value of the morphologic features for evaluating LNs, other two blinded radiologists independently interpreted the T2WI first and the combined image set of T2WI with DWI on a per-LN basis for the same study population with a four-week interval. The diagnostic predictive values were compared between the two reading sessions for each reader by using McNemar test. Pathology reports served as the reference standard.

226 LNs (54 metastatic and 172 non-metastatic LNs) were radiologic-pathologically matched and analyzed. Metastatic LNs showed amorphous subtle high or lobulating heterogeneous signal intensity (SI), whereas non-metastatic LNs showed dense bright dot on DWI (p=0.000001). The specificity and accuracy for metastatic LNs increased after adding DWI for both readers (specificity, from 59% to 73% for reader 1, from 41% to 68% for reader 2; accuracy, from 58% to 68% for reader 1, from 45% to 64% for reader 2, p<0.0001). However, the sensitivity was stationary for both readers (from 54% to 52%).

Metastatic LNs showed amorphous subtle high or lobulating heterogeneous SI on DWI. These additional morphologic characteristics provided better diagnostic specificity and accuracy than T2WI alone did for evaluating LNs in primary rectal cancer.

Metastatic LNs show different morphologic features from non-metastatic LNs on DWI. These additional morphologic characteristics can be useful for evaluating LNs in primary rectal cancer.

Cho, E, Kim, S, Yoon, J, Lim, Y, Lee, Y, Eun, C, Added Value of Morphologic Characteristics in Diffusion Weighted Imaging for Evaluating Lymph Nodes in Primary Rectal Cancer .  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044311.html