Michael Puesken

Global left-ventricular function assessment using dual-source multidetector CT: effect of improved temporal resolution on ventricular volume measurement

The purpose was to compare global left-ventricular (LV) function parameters measured with cine MRI with results from multiphase dual-source CT (DSCT) using 10 and 20 reconstruction phases. Twenty-eight patients with suspected or known CAD underwent DSCT coronary angiography. LV end-diastolic (EDV), end-systolic (ESV) and stroke volumes (SV), and ejection fraction (EF) were determined using LV segmentation and selection of specific phases from DSCT image sets reconstructed either at 5% or 10% steps through the R-R interval. Cine MRI served as the reference investigation. Threshold-based 3D-segmentation was feasible in all DSCT data sets. EDV and ESV were underestimated by DSCT, but showed excellent correlation (Pearson’s correlation coefficient 0.95/0.97) to values obtained with MRI. Using data from 5% DSCT image reconstructions instead of 10% phase reconstructions, the position of the ED and ES phase was changed in 16 of 28 patients; ESVs were to found to be slightly smaller, whereas EDV were slightly larger, resulting in a systematic overestimation of LV EF by 1.9% (p = 0.56). Threshold-based 3D segmentation enables accurate and reliable DSCT determination of global LV function with excellent correlation to cine MRI. Minor differences in LV EF indicate that both modalities are virtually interchangeable, even if the number of reconstructed phases is limited to 10% phase reconstructions.

Measurement Accuracy and Reproducibility of Semiautomated Metric and Volumetric Lymph Node Analysis in MDCT

OBJECTIVE The purpose of this study was to assess the measurement accuracy and reproducibility of semiautomated metric and volumetric lymph node analysis in MDCT. MATERIALS AND METHODS Whole-body CT with IV contrast administration was performed on 112 patients. Peripheral (cervical, axillary, and inguinal), abdominal, and thoracic lymph nodes were evaluated independently by two radiologists both manually and with semiautomated segmentation software. Long-axis diameter, short-axis diameter, and volume were measured. Agreement between the semiautomated and manual measurements (measurement error), need for manual correction, and relative interobserver differences were determined. Statistical analysis encompassed the variance inhomogeneity test, intraclass correlation coefficients, and Bland-Altman plots. RESULTS In total, 742 peripheral (cervical, axillary, and inguinal), abdominal, and thoracic lymph nodes (mean diameter, 13.2 ± 4.3 mm; range, 4-37 mm) were evaluated. Semiautomatic segmentation without need for further correction was possible for 480 of 742 lymph nodes (64.7%). Calculation of intraclass correlation coefficients revealed high correlation between manual and semiautomatic measurements (r = 0.70-0.81) with a slight trend toward size overestimation for semiautomatic short-axis diameter (14.3%; limits of agreement, -34.3%, 62.9%) and long-axis diameter (11.7%; limits of agreement, -25.2%, 48.5%). Bland-Altman plots showed significantly (p < 0.0001) lower interobserver differences for semiautomated short-axis diameter (1.2%; 95% CI, -39.9% to 42.3%) compared with the manual measurement (7.6%; 95% CI, -38.7% to 53.9%). Among all locations, the relative interobserver difference for semiautomatic volume (2.9%; 95% CI, -31.4% to 37.3%) was significantly lower than that for manual short-axis diameter (p < 0.0001), manual long-axis diameter (0.0178), and semiautomatic short-axis diameter (p < 0.0001). CONCLUSION Semiautomatic short-axis diameter, particularly volume measurements, of lymph nodes are, irrespective of location, precise in terms of reproducibility and appear to be considerably more reliable than manual lymph node assessment.

Prediction of lymph node manifestations in malignant lymphoma: significant role of volumetric compared with established metric lymph node analysis in multislice computed tomography.

Objective: Comparison of 2-dimensional and semiautomated 3-dimensional (3D) measurements to distinguish between benign and malignant lymph nodes in patients with malignant lymphoma. Methods: Whole-body positron emission tomography-computed tomography (PET-CT) was performed in 33 patients before therapy for malignant lymphoma. Two hundred fifty-seven peripheral lymph nodes (mean size, 13.4 ± 5.4 mm) were evaluated independently by 2 radiologists, both manually and with the use of semiautomated segmentation software. Long-axis diameter (LAD), short-axis diameter (SAD), maximal 3D diameter, volume, and elongation were measured. Positron emission tomography-CT and PET-CT follow-up and/or histology served as the reference standard. Statistical analysis encompassed intraclass correlation coefficients and receiver operating characteristic curves. Results: The standard of reference revealed involvement in 116 (45%) of 257 lymph nodes. Manual and semiautomated LAD and SAD showed good correlation with intraclass coefficients of 0.85 and 0.72, respectively. Semiautomated prediction of malignant lymph nodes revealed the highest areas under the receiver operating characteristic curves for volume (0.760; 95% confidence interval [CI], 0.639-0.887) followed by SAD (0.740; 95% CI, 0.616-0.862). The findings for LAD (0.722; 95% CI, 0.588-0.855), maximal 3D diameter (0.697; 95% CI, 0.565-0.830), and lymph node elongation (0.605; 95% CI, 0.466-0.745) were significantly lower (P < 0.05). Conclusions: Volumetric lymph node analysis is significantly superior compared with established LAD in the prediction of lymph node involvement and therefore can add to the definition of peripheral lymphoma target lesions.

Semiautomatic Lymph Node Segmentation in Multislice Computed Tomography: Impact of Slice Thickness on Segmentation Quality, Measurement Precision, and Interobserver Variability

Objectives:To determine the impact of slice thickness on semiautomatic lymph node analysis. Materials and Methods:Thoracic multislice computed tomography (MSCT) of 46 patients with NSCLC were reconstructed at 1.0-, 3.0-, and 5.0-mm slice thickness. Two radiologists independently determined long and short axis diameter and volume of 299 thoracic lymph nodes by semiautomatic segmentation software. Necessity of manual correction (= relative difference between uncorrected and corrected segmented lymph node volume) and relative interobserver differences were determined. The precision of segmentation was expressed by relative measurement deviations (RMD) from the reference standard (mean of 1.0 mm datasets). Statistical analysis encompassed t test and Bland-Altman plots. Results:Necessity of manual correction was significantly higher for 5.0 mm than for 3.0 (P = 0.042) or 1.0 mm (P = 0.0012). The RMD for long and short axis diameter were found to be independent of slice thickness, whereas the RMD for lymph node volume significantly (P = 0.021) increased from 4.0% at 1.0 mm (95% CI: 1.0%–3.5%) to 35% at 5.0 mm (95% CI: 10.5%–60.5%). The relative interobserver differences was consistently low for metric and volumetric parameters (eg, volume 2.3%, 95% CI: −7.4%–10.8% at 5.0 mm) with no difference in any of the slice thicknesses (P > 0.064). Conclusions:Significant deviations in lymph node volume together with excessive manual corrections suggest reconstruction of the data for semiautomatic lymph node assessment at a slice thickness of 1.0 mm but not exceeding 3.0 mm.

Usefulness of semi-automatic volumetry compared to established linear measurements in predicting lymph node metastases in MSCT

Background Volumetry of lymph nodes potentially better reflect asymmetric size alterations independently of lymph node orientation in comparison to metric parameters (e.g. long-axis diameter). Purpose To distinguish between benign and malignant lymph nodes by comparing 2D and semi-automatic 3D measurements in MSCT. Material and Methods FDG-18 PET-CT was performed in 33 patients prior to therapy for malignant melanoma at stage III/IV. One hundred and eighty-six cervico-axillary, abdominal and inguinal lymph nodes were evaluated independently by two radiologists, both manually and with the use of semi-automatic segmentation software. Long axis (LAD), short axis (SAD), maximal 3D diameter, volume and elongation were obtained. PET-CT, PET-CT follow-up and/or histology served as a combined reference standard. Statistics encompassed intra-class correlation coefficients and ROC curves. Results Compared to manual assessment, semi-automatic inter-observer variability was found to be lower, e.g. at 2.4% (95% CI 0.05–4.8) for LAD. The standard of reference revealed metastases in 90 (48%) of 186 lymph nodes. Semi-automatic prediction of lymph node metastases revealed highest areas under the ROC curves for volume (reader 1 0.77, 95%CI 0.64–0.90; reader 2 0.76, 95%CI 0.59–0.86) and SAD (reader 1 0.76, 95%CI 0.64–0.88; reader 2 0.75, 95%CI 0.62–0.89). The findings for LAD (reader 1 0.73, 95%CI 0.60–0.86; reader 2 0.71, 95%CI 0.71, 95%CI 0.57–0.85) and maximal 3D diameter (reader 1 0.70, 95%CI 0.53-0.86; reader 2 0.76, 95%CI 0.50–0.80) were found substantially lower and for elongation (reader 1 0.65, 95%CI 0.50–0.79; reader 2 0.66, 95%CI 0.52–0.81) significantly lower (p < 0.05). Conclusion Semi-automatic analysis of lymph nodes in malignant melanoma is supported by high segmentation quality and reproducibility. As compared to established SAD, semi-automatic lymph node volumetry does not have an additive role for categorizing lymph nodes as normal or metastatic in malignant melanoma.

Microbiologic Contamination and Time Efficiency of Use of Automatic MDCT Injectors With Prefilled Syringes: Results of a Clinical Investigation

OBJECTIVE Multiple use of syringes in automatic injectors is considered to place patients at risk of septic complications. The purpose of this study was to evaluate the microbiologic contamination and time efficiency associated with routine clinical use of single-use prefilled disposable syringes for contrast administration. SUBJECTS AND METHODS To ensure a hygienic background, imprints of devices and the palms of the hands of staff members were microbiologically analyzed before the clinical investigation. The microbiologic contamination of prefilled contrast and saline syringes was analyzed according to two protocols: single use of prefilled contrast syringes and saline syringes (n = 60) and single use of prefilled contrast syringes but multiple use of saline syringes for four injections or patients (n = 60). The time required for assembly of the injection system and filling and refilling for each protocol was measured. RESULTS Contamination of the surfaces of devices and palms in the CT department was within the acceptable range for hygienic conditions. Prefilled disposable syringes for the contrast agent and saline solution used once had no microbiologic contamination. Microbial contamination with coagulase-negative staphylococci was found in two saline syringes used repeatedly. The time for assembly of the injection system and installation of prefilled syringes did not differ significantly (p = 0.45) between the single-use protocol (2.3 +/- 1.1 minutes) and the multiple-use protocol (2.0 +/- 1.4 minutes). CONCLUSION Use of prefilled contrast syringes with single-use saline syringes is associated with time-efficient assembly of injection systems and prevents microbiologic contamination in clinical routine, especially in the care of immunocompromised patients.

Automatic MDCT Injectors: Hygiene and Efficiency of Disposable, Prefilled, and Multidosing Roller Pump Systems in Clinical Routine

OBJECTIVE This study evaluated three different injection systems with regard to microbiological contamination, time efficiency, and user handling during a clinical routine. SUBJECTS AND METHODS A total of 825 patients were included. A double-syringe contrast injector with disposable syringes (system A; n = 150) and one that used prefilled syringes (system B; n = 150) were microbiologically analyzed during single use of the syringes in one patient. Moreover, the contamination of a roller pump injector capable of multidosing several patients from a contrast agent container, without the need for prior filling, was determined after being used for an entire day (system C; n = 35 injections/day for 15 days). The hygienic background was guaranteed by taking imprints of the surfaces of devices and the palms of the hands of members of CT staff before the clinical investigation. The time required for assembly of the injection systems and for filling or refilling of each injector system was measured. The handling of the three systems also was subjectively ranked by the technicians. RESULTS Injection systems A, B, and C remained microbiologically sterile and free of contamination throughout their use in clinical routine. The mean (± SD) time for injection system assembly and installation of syringes and filling did not differ significantly between injection systems A and B (system A, 2.5 ± 1.1 minutes; system B, 1.9 ± 1.3 minutes; p = 0.12), whereas the time for assembly of system C was significantly shorter (0.9 ± 0.6 minutes; p < 0.05 vs system A; p < 0.05 vs system B). In the subjective ranking of injector handling, systems B and C were preferred. CONCLUSION Double-syringe injectors used with disposable or prefilled contrast agent syringes, as well as roller pump injectors, ensure hygienic conditions in clinical routine. However, time efficiency and handling are aspects that favor prefilled and roller pump systems.

Implementation of ultra-low-dose lung protocols in CT-guided lung biopsies: feasibility and safety in the clinical setting:

Objective To evaluate the use of ultra-low-dose computed tomography (ULDCT) for CT-guided lung biopsy versus standard-dose CT (SDCT). Methods CT-guided lung biopsies from 115 patients (50 ULDCT, 65 SDCT) were analyzed retrospectively. SDCT settings were 120 kVp with automatic mAs modulation. ULDCT settings were 80 kVp with fixed exposure (20 mAs). Two radiologists evaluated image quality (i.e., needle artifacts, lesion contouring, vessel recognition, visibility of interlobar fissures). Complications and histological results were also evaluated. Results ULDCT was considered feasible for all lung interventions, showing the same diagnostic accuracy as SDCT. Its mean total radiation dose (dose–length product) was significantly reduced to 34 mGy-cm (SDCT 426 mGy-cm). Image quality and complication rates (P = 0.469) were consistent. Conclusions ULDCT for CT-guided lung biopsies appears safe and accurate, with a significantly reduced radiation dose. We therefore recommend routine clinical use of ULDCT for the benefit of patients and interventionalists.

Can computed tomography volumetry of the renal cortex replace MAG3-scintigraphy in all patients for determining split renal function?

OBJECTIVES The current gold standard for determination of split renal function (SRF) is Tc-99m-mercapto-acetyltriglycin (MAG3) scintigraphy. Initial studies comparing MAG3-scintigraphy and CT-based renal cortex volumetry (RCV) for calculation of SRF have shown similar results in highly selected patient collectives with normal renal function (i.e. living kidney donors). This study aims to compare MAG3-scintigraphy and CT-RCV within a large unselected patient collective including patients with impaired renal function. MATERIALS AND METHODS For this assessment, 279 datasets (131 men, 148 women; mean age: 54.2 ± 12.9 years, range: 24-84 years) of patients who underwent MAG3-scintigraphy and contrast-enhanced abdominal CT within two weeks were retrospectively analyzed. Two independent readers assessed the CT-RCV in all CT datasets using a semi-automated volumetry tool. The MAG3-scintigraphy and CT-RCV methods were compared, stratified for the eGFR. Statistical analysis included descriptive statistics as well as inter- observer agreement. RESULTS The absolute mean difference between the percentage contribution of the left and the right kidneys in total MAG3-clearance was 8.6%. Independent of eGFR, an overall sufficient agreement between both methods was established in all patients. A relatively small, tolerable systemic error resulted in an underestimation (max. 2%) of the left renal contribution to overall RCV. CONCLUSION The results demonstrate that CT-RCV is a potential clinical replacement for MAG3-scintigraphy for calculation of SRF: CT-RCV demonstrates clinically tolerable differences with MAG3-scintigraphy, independent of patient eGFR. The relative complexity of the RCV method utilized is a potential limitation and may have contributed to the acceptable but only fair to moderate level of intra-reader reliability.

Cardiac: Left / Right Ventricular Function

Left-ventricular volumes and myocardial mass are independent predictors of morbidity and mortality in patients with coronary heart disease, and global left-ventricular function is considered the strongest determinant of heart failure and death due to myocardial infarction. The accurate and reproducible determination of left-ventricular volumetric and functional parameters is important for clinical diagnosis and risk stratification in patients with suspected or documented coronary heart disease.1