van Peter Ooijen

Management of Lung Nodules Detected by Volume CT Scanning

BACKGROUND The use of multidetector computed tomography (CT) in lung-cancer screening trials involving subjects with an increased risk of lung cancer has highlighted the problem for the clinician of deciding on the best course of action when noncalcified pulmonary nodules are detected by CT. METHODS A total of 7557 participants underwent CT screening in years 1, 2, and 4 of a randomized trial of lung-cancer screening. We used software to evaluate a noncalcified nodule according to its volume or volume-doubling time. Growth was defined as an increase in volume of at least 25% between two scans. The first-round screening test was considered to be negative if the volume of a nodule was less than 50 mm(3), if it was 50 to 500 mm(3) but had not grown by the time of the 3-month follow-up CT, or if, in the case of those that had grown, the volume-doubling time was 400 days or more. RESULTS In the first and second rounds of screening, 2.6% and 1.8% of the participants, respectively, had a positive test result. In round one, the sensitivity of the screen was 94.6% (95% confidence interval [CI], 86.5 to 98.0) and the negative predictive value 99.9% (95% CI, 99.9 to 100.0). In the 7361 subjects with a negative screening result in round one, 20 lung cancers were detected after 2 years of follow-up. CONCLUSIONS Among subjects at high risk for lung cancer who were screened in three rounds of CT scanning and in whom noncalcified pulmonary nodules were evaluated according to volume and volume-doubling time, the chances of finding lung cancer 1 and 2 years after a negative first-round test were 1 in 1000 and 3 in 1000, respectively. (Current Controlled Trials number, ISRCTN63545820.)

Multidetector computed tomography-guided treatment strategy in patients with non-ST elevation acute coronary syndromes: a pilot study

Patients with non-ST elevation acute coronary syndrome (ACS) and evidence of myocardial ischaemia are scheduled for coronary angiography (CAG). In most patients CAG remains a single diagnostic procedure only. A prospective study was performed to evaluate whether 16-slice multidetector CT (MDCT) could predict treatment of the patients and to determine how many CAGs could have been prevented by MDCT scanning prior to CAG. Twenty-two patients with ACS were scanned prior to CAG. Based on MDCT data, a fictive treatment was proposed and compared to CAG-based treatment. Excellent accuracy was observed to detect significant stenoses using MDCT (sensitivity 94%, specificity 96%). In 45%, no PCI was performed during CAG, because of the absence of significant coronary artery disease (27%) or severe coronary artery disease, demanding CABG (18%). MDCT predicted correct treatment in 86%. By using MDCT data, 32% of the CAGs could have been prevented.

Non-invasive coronary artery imaging with electron beam computed tomography and magnetic resonance imaging

ecent developments in hardware and software have increased the diagnostic capabilities of magnetic resonance imaging (MRI) and electron beam computed tomography (EBT) to visualise the cardiac anatomy, including the coronary arteries. Visualisation of the heart puts any diagnostic technique to the test, because the continuous cardiac motion distorts the image and high temporal resolution is required to “freeze” the heart to produce a sharp image. In particular, non-invasive visualisation of the coronary arteries is diYcult because of the small size of the coronary arteries (2‐5 mm in diameter), the complex, tortuous course making it often impossible to “catch” the coronary artery in one slice (tomogram), and the cardiac and respiratory motion causing loss of sharpness or motion artefacts. In this article image acquisition and processing techniques of MRI and EBT will be presented. The clinical role of both techniques in cardiac imaging will be discussed, together with a brief introduction of the technical aspects.

Assessment of image quality of 64-row Dual Source versus Single Source CT coronary angiography on heart rate: A phantom study

PURPOSE To assess the influence of temporal resolution on image quality of computed tomographic (CT) coronary angiography by comparing 64-row Dual Source CT (DSCT) and Single Source CT (SSCT) at different heart rates. METHODS An anthropomorphic moving heart phantom was scanned at rest, and at 50 beats per minute (bpm) up to 110 bpm, with intervals of 10 bpm. 3D volume rendered images and curved multi-planar reconstructions (MPRs) were acquired and image quality of the coronary arteries was rated on a 5-points scale (1=poor image quality with many artefacts, 5=excellent image quality) for each heart rate and each scanner by 3 observers. Paired sample t-test and Wilcoxon Signed Ranks test were used to assess clinically relevant differences between both modalities. RESULTS The mean image quality scores at 70, 100 and 110 bpm were significantly higher for DSCT compared to SSCT. The overall mean image quality scores for DSCT (4.2+/-0.6) and SSCT (3.0+/-1.1) also differed significantly (p<0.001). CONCLUSION These initial results show a clinically relevant overall higher image quality for DSCT compared to SSCT, especially at heart rates of 70, 100 and 110 bpm. With its comparatively high image quality and low radiation dose, DSCT appears to be the method of choice in CT coronary angiography at heart rates above 70 bpm.

Incorporating out-patient data from CD-R into the local PACS using DICOM worklist features

With the introduction of digital imaging in radiology, CD-Rs are increasingly used to distribute patient materials. This study investigates the application of a new software package and work protocol to integrate out-hospital data into the local PACS (picture archive and communication system) archive, which is hampered by differences in patient numbers. A one-month trial was started to import CD-Rs from two departments (radiotherapy and radiology). Seventy CD-Rs were collected from 20 different hospitals holding data of eight different modality types and published by eight different software packages from different vendors. All CD-Rs were successfully transferred into the PACS. The new software and work protocol provide an easy way of introducing the out-hospital data into the PACS. CD-Rs can be destroyed after transfer to PACS, eliminating physical storage. Furthermore, all data can now be viewed and reported using the default viewers of the hospital and no additional training of staff is required.

Evaluation of the use of CD-ROM upload into the PACS or institutional web server

PurposePatient data are increasingly distributed between hospitals using CD-ROMs instead of actual films. This introduces problems because different viewers from different vendors are provided, and sometimes viewers are unusable because local software installation is not allowed. In 2004, we started to facilitate the incorporation of CD-ROM data into the normal workflow of the hospital by using commercially available software to perform patient reconciliation based on the DICOM (digital imaging and communication in medicine) modality worklist. The purpose of the current study is to evaluate this new procedure.Methods and MaterialsA questionnaire was sent to all users to evaluate the satisfaction with the current facility and to evaluate possible improvements. Several quality parameters on speed and satisfaction were rated on a 5-point scale (1 = bad to 5 = excellent).ResultsReplies from 17 different respondents were evaluated, accounting for an average of 76 CD-ROMs per week. Mean (median) results showed a score of 3.6 (4) for handling time, 3.4 (4) for archival of second opinion data, 3.8 (median 4) for archival of external data onto the web server, and 4.5 (median 5) for the overall performance of the current procedure.ConclusionAlthough some improvements can be made, storage of the study data from CDs from outpatients into PACS (picture archiving and communication system) and web server already provides for an existing need. Using this service, physicians can access the data with ease and familiarity. User satisfaction with the provided solution is high.

Semi-automatic measurement of left ventricular function on dual source computed tomography using five different software tools in comparison with magnetic resonance imaging

PURPOSE To compare left ventricular (LV) function assessment using five different software tools on the same dual source computed tomography (DSCT) datasets with the results of MRI. MATERIALS AND METHODS Twenty-six patients, undergoing cardiac contrast-enhanced DSCT were included (20 men, mean age 59±12 years). Reconstructions were made at every 10% of the RR-interval. Function analysis was performed with five different, commercially available workstations. In all software tools, semi-automatic LV function measurements were performed, with manual corrections if necessary. Within 0-22 days, all 26 patients were scanned on a 1.5 T MRI-system. Bland-Altman analysis was performed to calculate limits of agreement between DSCT and MRI. Pearsons correlation coefficient was calculated to assess the correlation between the different DSCT software tools and MRI. Repeated measurements were performed to determine intraobserver and interobserver variability. RESULTS For all five DSCT workstations, mean LV functional parameters correlated well with measurements on MRI. Bland-Altman analysis of the comparison of DSCT and MRI showed acceptable limits of agreement. Best correlation and limits of agreement were obtained by DSCT software tools with software algorithms comparable to MRI software. CONCLUSION The five different DSCT software tools we examined have interchangeable results of LV functional parameters compared to regularly analysed results by MRI. The best correlation and the narrowest limits of agreement were found when the same software algorithm was used for both DSCT and MRI examinations, therefore our advice for clinical practice is to always evaluate images with the same type of post-processing tools in follow-up.

Inter- and intrascanner variability of pulmonary nodule volumetry on low-dose 64-row CT : an anthropomorphic phantom study

OBJECTIVE To assess inter- and intrascanner variability in volumetry of solid pulmonary nodules in an anthropomorphic thoracic phantom using low-dose CT. METHODS Five spherical solid artificial nodules [diameters 3, 5, 8, 10 and 12 mm; CT density +100 Hounsfield units (HU)] were randomly placed inside an anthropomorphic thoracic phantom in different combinations. The phantom was examined on two 64-row multidetector CT (64-MDCT) systems (CT-A and CT-B) from different vendors with a low-dose protocol. Each CT examination was performed three times. The CT examinations were evaluated twice by independent blinded observers. Nodule volume was semi-automatically measured by dedicated software. Interscanner variability was evaluated by Bland-Altman analysis and expressed as 95% confidence interval (CI) of relative differences. Intrascanner variability was expressed as 95% CI of relative variation from the mean. RESULTS No significant difference in CT-derived volume was found between CT-A and CT-B, except for the 3-mm nodules (p<0.05). The 95% CI of interscanner variability was within ±41.6%, ±18.2% and ±4.9% for 3, 5 and ≥8 mm nodules, respectively. The 95% CI of intrascanner variability was within ±28.6%, ±13.4% and ±2.6% for 3, 5 and ≥8 mm nodules, respectively. CONCLUSION Different 64-MDCT scanners in low-dose settings yield good agreement in volumetry of artificial pulmonary nodules between 5 mm and 12 mm in diameter. Inter- and intrascanner variability decreases at a larger nodule size to a maximum of 4.9% for ≥8 mm nodules. ADVANCES IN KNOWLEDGE The commonly accepted cut-off of 25% to determine nodule growth has the potential to be reduced for ≥8 mm nodules. This offers the possibility of reducing the interval for repeated CT scans in lung cancer screenings.

A 16-slice multidetector computed tomography protocol for evaluation of the gastroepiploic artery grafts in patients after coronary artery bypass surgery

Arterial coronary bypass grafts [internal mammary arteries and gastroepiploic artery (GEA)] are in widespread use for coronary surgery. Since selective catheterisation of the GEA graft to monitor patency, is often unsuccessful, a non-invasive protocol to visualise the GEA-graft from origin to anastomosis is presented using 16-slice multidetector computed tomography (MDCT). Twenty-six male patients (mean age 58.1±6.7 years) with GEA grafts were scanned according to a protocol of an ECG-synchronised cardiac scan followed by a thoracoabdominal scan. To terminate the scan at the correct anatomical level, the lowest level of the GEA was coded based on the lumbar vertebrae level. Scores ranging from one (excellent) to four (bad) were assigned to evaluate visualisation quality of the grafts. GEA grafts were assessable in 62% of the thoracoabdominal scans and 69% of the cardiac scans. On average, the lowest part of the GEA corresponded with a level between L1 and L2, in two cases in the upper part of L3. Mean visualisation score in the thoracoabdominal scans and cardiac scans was good (respectively 1.4±0.6 and 1.4±1.0). Sixteen-slice MDCT is a promising alternative for catheterisation in evaluating patency of GEA grafts, using the presented protocol with thoracoabdominal scan including L3 for complete coverage of the GEA graft.

In vivo assessment of three dimensional coronary anatomy using electron beam computed tomography after intravenous contrast administration

Intravenous coronary angiography with electron beam computed tomography (EBCT) allows for the non-invasive visualisation of coronary arteries. With dedicated computer hardware and software, three dimensional renderings of the coronary arteries can be constructed, starting from the individual transaxial tomograms. This article describes image acquisition, postprocessing techniques, and the results of clinical studies. EBCT coronary angiography is a promising coronary artery imaging technique. Currently it is a reasonably robust technique for the visualisation and assessment of the left main and left anterior descending coronary artery. The right and circumflex coronary arteries can be visualised less consistently. Improvements in image acquisition and postprocessing techniques are expected to improve visualisation and diagnostic accuracy of the technique.