Yasutaka Kawamura, Presenter: Nothing to Disclose

Motoo Kubuta, Abstract Co-Author: Nothing to Disclose

Ikuo Yamazaki MD, Abstract Co-Author: Nothing to Disclose

Toshihiro O'Uchi MD, Abstract Co-Author: Nothing to Disclose

Spinal arachnoid cysts may cause symptoms due to a mass effect on cord and/or nerve roots. Communicating arachnoid cyst is hardly visualized because of its iso-density/intensity to CSF on CT and MRI and lack of enhancement. Since it is important to depict the check-valve orifice of the cyst for surgical treatment, the dynamic CT myelography (CTM) and Cine-MRI were performed.

Eighteen cases were evaluated for spinal intradural arachnoid cyst for four years. MRI with 1.5T unit (SIEMENS, Avanto) and conventional CT (Toshiba) were performed in all cases. When communicating arachnoid cyst was suspected, cine-MRI was taken (six cases), and contrast enhanced MRI was performed in nine cases (four with arachnoiditis). CTM was performed for 12 cases, with injection of contrast media within CT gantry for three cases.

Four out of 18 cases, MRI demonstrated irregular dural adhesion of spinal cord without clear cyst formation. In the other fourteen cases, MRI, CT and CTM showed anterior cord deviation and splitting nerve routs consistent with arachnoid cyst. Seven out of the 14 cases on CTM, the immediate contrast filling within the cyst  made it difficult to make the diagnosis of the communicating arachnoid cyst and to explain the pressure insult on the spinal cord. Cine-MRI showed subtle inhomogenuity partially in those cysts with suspicion of the opening of the communicating arachnoid cyst. In two of three cases on the dynamic CTM, the entrance of the contrast media could be interpreted as the check-valve orifice of the communicating arachnoid cyst. The diagnosis of communicating arachnoid cyst was confirmed by surgery in those seven cases, and in all cases surgical resection of arachnoid capsule including the check-valve orifice improved patient symptoms and imaging abnormality.

The diagnosis of communicating arachnoid cyst as the cause of myelomalacia is sometimes difficult. In our study, careful interpretation of cine-MRI and CTM including the dynamic technique could demonstrate the check-valve orifice of the communicating arachnoid cyst and be helpful o\for surgery as well as for understanding its causative mechanism of mass effects on the spinal cord.

Cine-MRI and; the dynamic CTM can show the orifice of the communicating arachnoid cyst and to be helpful for surgery as well as for understanding its check-valve mechanism.

Kawamura, Y, Kubuta, M, Yamazaki, I, O'Uchi, T, Detecting the Check-valve Orifice in Communicating Intradural Arachnoid Cyst Developing Mass Effect on Spinal Cord with Cine-MRI and the Dynamic CT Myelography.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034620.html