New Techniques for Intracranial Stent Navigation in Patients with Tortuous Arteries

PURPOSE: We wanted to describe several new techniques of intracranial stenting that are helpful for navigating the stent delivery system in the tortuous carotid or vertebral arteries. MATERIALS AND METHODS: Between May 1998 and June 2004, 65 patients with 73 symptomatic, stenotic intracranial arteries (more than 50%) were successfully treated with stent-assisted angioplasty. In eleven of the total cases, the standard technique failed to navigate the stent delivery system into the objective lesion because of the tortuous path of the carotid or vertebral arteries. In these cases, several new techniques were used to overcome the vessels' tortuous path. The several new techniques were 1) the waiting method (20-30 minutes) after advancement of microwire across the lesion; 2) the double wires technique using an additional microwire; and 3) the coaxial double guiding catheters technique using an additional smaller guiding catheter. Five lesions were located in the middle cerebral arteries, four were in the supraclinoid internal carotid arteries, and two were in the distal vertebral arteries. RESULTS: In all difficult cases, intracranial artery stenting was performed successfully by using the several new techniques. The waiting method made smooth stent navigation possible in 5 cases, the double wire technique was successful in 4 cases and the coaxial double guiding catheter technique was successful in 2 case. There was no complication related to the new techniques. CONCLUSION: In difficult cases where the standard technique failed to navigate the stent delivery system into the objective lesion because of the vessels' tortuous path, these new techniques for intracranial stent navigation were usefully implemented.

Usefulness of Multiplanar Reformatted Images of Multi-detector Row Helical CT in Assessment of Biliary Stent Patency

PURPOSE: To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a self-expandable metallic stent due to malignant biliary obstruction. MATERIALS AND METHODS: Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metallic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. RESULTS: Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. CONCLUSION: Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessement of stent patency and the precise level of obstruction when stent obstrution is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases.

The Usefulness of Multiplanar Reconstruction Images in Preoperative T-staging of Advanced Gastric Cancer

PURPOSE: The purpose of this study was to evaluate the performance of multidetector-row CT (MDCT) in the preoperative T-staging of patients with advanced gastric cancer. MATERIALS AND METHODS: A total of 65 patients with an established diagnosis of advanced gastric cancer (T2 or more) were evaluated with MDCT. The protocol of MDCT consisted of high-quality (HQ) mode helical scanning with a slice thickness of 2.5 mm. The axial CT images were reconstructed with a slice thickness of 5 mm. MPR images were reconstructed from the raw axial data with a slice thickness of 5 mm. A comparison between the standard axial and axial MPR images was performed by two radiologists with regard to the evaluation of the tumor location and T-stage. These findings were compared with the pathologic and surgical findings. RESULTS: T-staging of the advanced stomach cancer was correct in 89% (58/65) and 69% (45/65) of the MPR images and axial images, respectively. The MPR images improved the detection rate (5 lesions)of the tumors and increased the accuracy of the T-staging (13 lesions) in comparison with the axial images. The MPR images are of greater diagnostic value for the evaluation of omental seeding (5 lesions: axial images, 9 lesions: MPR images), tumor location and extension. CONCLUSION: Multiplanar reconstruction (MPR) images provide increased confidence in the location and T-staging of certain cases of advanced gastric cancer, such as those in locations where CT images are susceptible to be affected by the difficulties associated with partial volume averaging. In this study, the MPR images provided more precise information about the tumor location and T-staging than the standard axial images in the preoperative evaluation of advanced gastric cancer.