Yeo Goon Kim MD, Presenter: Nothing to Disclose

Joon Woo Lee, Abstract Co-Author: Nothing to Disclose

Heung Sik Kang MD, Abstract Co-Author: Nothing to Disclose

Jae Hyoung Kim, Abstract Co-Author: Nothing to Disclose

Kyung Seok Park MD, PhD, Abstract Co-Author: Nothing to Disclose

Park Seung Ho, Abstract Co-Author: Nothing to Disclose

The purpose of this study is to compare the diffusion characteristics of idiopathic acute transverse myelitis (ATM) and acute spinal cord infarction (SCI).

DWI and ADC map were prospectively obtained from the patients showing myelopathy from February 2006 to April 2009. Inclusion criteria required the presence of intramedullary high signal on sagittal T2-weighted images and a final diagnosis of idiopathic ATM or SCI. The diagnosis of either idiopathic ATM or SCI was established by one neurologist with the clinical course and the criteria of the Transverse Myelitis Consortium group. Finally, 19 patients (M:F = 12:7; mean age, 45 years; range, 29-66 years) with idiopathic ATM and four patients (M:F = 1:3; mean age, 54 years; range, 48-64 years) with SCI were included in this study. Eight patients were also included in the idiopathic ATM from the previous study about diffusion tensor images. Two radiologists evaluated the DWI and ADC map in consensus. They also evaluated T2-sagittal images, focusing on the extent of the signal change.

Among the 19 patients with ATM, two showed restricted diffusion and one showed increased diffusion on the ADC map. The extent of the signal change was four and two spine segments in those two patients with idiopathic ATM and restricted diffusion, respectively, and four spine segments in one patient with idiopathic ATM and increased diffusion. Most of the patients (16 of 19) with ATM did not show restricted diffusion on their ADC maps. In 10 of 16 patients with idiopathic ATM and an iso-signal on the ADC map, high signal intensity on DWI was observed that was thought to be a T2 shine-through effect. The extent of signal change in those 10 patients with a T2 shine-through effect were 2.6 spine segments on average, ranging from one to seven. The other six patients with idiopathic ATM showed iso-signal intensity on both the DWI and the ADC map. All of these six patients had less than one segmental ivnolnement. All four patients with SCI showed restricted diffusion irrespective of the extent of the signal change.

Idiopathic ATM usually does not demonstrate restricted diffusion, which can be a clue to differentiate from spinal-cord infarct. However, idiopathic ATM could rarely show the diffusion change in larger segment involvement.

DWI with ADC map would aid differentiating ATM from SCI in patients with acute myeolpathy.

Kim, Y, Lee, J, Kang, H, Kim, J, Park, K, Seung Ho, P, The Role of Diffusion-weighted MRI on Differentiating Idiopathic Acute Transverse Myelitis and Acute Spinal Cord Infarction.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8005777.html