While specialized workstations have traditionally been used to generate apparent diffusion coefficient (ADC) measurements necessary for quantitative analysis of diffusion-weighted MR imaging (DWI-MR), PACS software works equally well in accomplishing this task, according to a study conducted by a research team from the Department of Radiology of the Pennsylvania State University College of Medicine at Milton S. Hershey Medical Center, Hershey, Pa.
Led by Reem M. El Kady and published exclusively in the online edition of the American Journal of Roentgenology, (March 2011, Vol. 196:3, W280-W284), the study indicates that PACS workstation software can be as accurate as specialized workstations in generating ADC measurements, thereby eliminating any workflow barriers to more frequent use of these tools and increasing their correlation with other imaging findings. "In this study, we found no significant difference between the ADC measurements obtained from a commercially available dedicated workstation, which was a direct extension and mirror image of the main MRI console specifically provided by the MRI vendors for all post-processing, and those obtained from our PACS system," the authors write. "The differences between both readings were very small irrespective of the type of pathologic abnormality or the MRI platform used, and any difference likely represented slight difference in size and shape of the ROI placed on the two systems."
El Kady and his colleagues, Arabinda Kumar Choudhary and Rafel Tappouni, compared the accuracy of ADC values made with PACS workstations and dedicated workstations by performing a retrospective review of 79 patients with 120 liver lesions of more than 5 mm in diameter. All lesions were clearly demonstrable on the PACS workstation. Patients were scanned on one of three 1.5T MRI platforms, with a surface coil used for average-weight patients and a body coil, for obese patients. Standard abdominal MRI sequences were employed. Liver biopsies yielded the final diagnosis in 31 patients; dynamic MRI and follow-up, in the remaining 48 patients. A range of liver lesions, from highly cellular metastatic to cystic, were included in the research.
ADC maps were initially generated automatically on the main MRI console, and the ADC value for each lesion was measured using a separate, dedicated post-processing workstation by placing a region of interest (ROI) on each lesion. The researchers then measured the ADC values for each lesion again via iSite PACS software from Philips, and a two-sample t-test was used to compare the values for both the PACS and dedicated workstations..ADC values measured on the dedicated workstation were 0.4-4.38 x 10-3 mm2/sec. The PACS produced ADC values of 0.42-4.35 x 10-3 mm2/sec. The difference was not statistically significant, according to the researchers, who also found similarvalues across different pathologic abnormalities and different MRI magnets.