Data management solution for large-volume computed tomography in an existing picture archiving and communication system (PACS).

Multidetector row computed tomography (MDCT) creates massive amounts of data, which can overload a picture archiving and communication system (PACS). To solve this problem, we designed a new data storage and image interpretation system in an existing PACS. Two MDCT image datasets, a thick- and a thin-section dataset, and a single-detector CT thick-section dataset were reconstructed. The thin-section dataset was archived in existing PACS disk space reserved for temporary storage, and the system overwrote the source data to preserve available disk space. The thick-section datasets were archived permanently. Multiplanar reformation (MPR) images were reconstructed from the stored thin-section datasets on the PACS workstation. In regular interpretations by eight radiologists during the same week, the volume of images and the times taken for interpretation of thick-section images with (246 CT examinations) or without (170 CT examinations) thin-section images were recorded, and the diagnostic usefulness of the thin-section images was evaluated. Thin-section datasets and MPR images were used in 79% and 18% of cases, respectively. The radiologists' assessments of this system were useful, though the volume of images and times taken to archive, retrieve, and interpret thick-section images together with thin-section images were significantly greater than the times taken without thin-section images. The limitations were compensated for by the usefulness of thin-section images. This data storage and image interpretation system improves the storage and availability of the thin-section datasets of MDCT and can prevent overloading problems in an existing PACS for the moment.

Clinical usefulness of temporal subtraction method in screening digital chest radiography with a mobile computed radiography system.

The temporal subtraction image which is obtained by subtraction of a previous image from a current image of the same patient can enhance interval changes. In this study, we applied the temporal subtraction method for lung cancer screening and evaluated the clinical usefulness by comparing the review time and the detection accuracy of lung cancers without and with subtraction images. Since 1996, we have been performing screening chest radiography for a mass survey of lung cancers in the Iwate Prefecture, Japan, by using a van equipped with a computed radiography system and a digital archive system. During the 12 years from 1997 to 2008, a total of 186,340 examinations were performed, and 121,526 (65.2%) temporal subtraction images were provided in the lung cancer screening. Twenty-four abnormal cases with lung cancer and 270 normal cases were selected from the lung cancer screening. Five radiologists participated in an observer performance study and interpreted previous and current chest radiographs without and with temporal subtraction images. In addition, radiologists interpreted previous and current images with a double-reading method. The average ROC curves demonstrated a significant improvement in the detection accuracy of lung cancers with the temporal subtraction images compared with that without the temporal subtraction images, and that with the double-reading method. Therefore, we believe strongly that the temporal subtraction method is clinically useful for radiologists in the detection of lung cancers in mass surveys.