Comparison of manual and semi-automatic measuring techniques in MSCT scans of patients with lymphoma: a multicentre study.

OBJECTIVES: Multicentre evaluation of the precision of semi-automatic 2D/3D measurements in comparison to manual, linear measurements of lymph nodes regarding their inter-observer variability in multi-slice CT (MSCT) of patients with lymphoma. METHODS: MSCT data of 63 patients were interpreted before and after chemotherapy by one/two radiologists in five university hospitals. In 307 lymph nodes, short (SAD)/long (LAD) axis diameter and WHO area were determined manually and semi-automatically. Volume was solely calculated semi-automatically. To determine the precision of the individual parameters, a mean was calculated for every lymph node/parameter. Deviation of the measured parameters from this mean was evaluated separately. Statistical analysis entailed intraclass correlation coefficients (ICC) and Kruskal-Wallis tests. RESULTS: Median relative deviations of semi-automatic parameters were smaller than deviations of manually assessed parameters, e.g. semi-automatic SAD 5.3 vs. manual 6.5 %. Median variations among different study sites were smaller if the measurement was conducted semi-automatically, e. g. manual LAD 5.7/4.2 % vs. semi-automatic 3.4/3.4 %. Semi-automatic volumetry was superior to the other parameters (2.8 %). CONCLUSIONS: Semi-automatic determination of different lymph node parameters is (compared to manually assessed parameters) associated with a slightly greater precision and a marginally lower inter-observer variability. These results are with regard to the increasing mobility of patients among different medical centres and in relation to the quality management of multicentre trials of importance. KEY POINTS: • In a multicentre setting, semi-automatic measurements are more accurate than manual assessments. • Lymph node volumetry outperforms all other semi-automatically and manually performed measurements. • Use of semi-automatic lymph node analyses can reduce the inter-observer variability.

Therapy response evaluation of malignant lymphoma in a multicenter study: comparison of manual and semiautomatic measurements in CT.

PURPOSE: Comparison of manual one-/bi-dimensional measurements versus semi-automatically derived one-/bi-dimensional and volumetric measurements for therapy response evaluation of malignant lymphoma during CT follow-up examinations in a multicenter setting. MATERIALS AND METHODS: MSCT data sets of patients with malignant lymphoma were evaluated before (baseline) and after two cycles of chemotherapy (follow-up) at radiological centers of five university hospitals. The long axis diameter (LAD), the short axis diameter (SAD) and the bi-dimensional WHO of 307 target lymph nodes were measured manually and semi-automatically using dedicated software. Lymph node volumetry was performed semi-automatically only. The therapeutic response was evaluated according to lymphoma-adapted RECIST. RESULTS: Based on a single lymph node, semi-automatically derived multidimensional parameters allowed for significantly more accurate therapy response classification than the manual or the semi-automatic unidimensional parameters. Incorrect classifications were reduced by up to 9.6%. Compared to the manual approach, the influence of the study center on correct therapy classification is significantly less relevant when using semi-automatic measurements. CONCLUSION: Semi-automatic volumetry and bi-dimensional WHO significantly reduce the number of incorrectly classified lymphoma patients by approximately 9.6% in the multicenter setting in comparison to linear parameters. Semi-automatic quantitative software tools may help to significantly reduce wrong classifications that are associated with the manual assessment approach. KEY POINTS: ► Semi-automatic volumetry and bi-dimensional WHO significantly reduce the number of incorrectly classified lymphoma patients ► Manual lymph node evaluation with uni-dimensional parameters is inferior to semi-automatic analysis in a multicenter setting ► Semi-automatic quantitative software tools should be introduced in clinical study evaluation.

Lung segment geometry study: simulation of largest possible tumours that fit into bronchopulmonary segments.

BACKGROUND: Segmental resection in stage I non-small cell lung cancer (NSCLC) has been well described and is considered to have similar survival rates as lobectomy but with increased rates of local tumour recurrence due to inadequate parenchymal margins. In consequence, today segmentectomy is only performed when the tumour is smaller than 2 cm. METHODS: Three-dimensional reconstructions from 11 thin-slice CT scans of bronchopulmonary segments were generated, and virtual spherical tumours were placed over the segments, respecting all segmental borders. As a next step, virtual parenchymal safety margins of 2 cm and 3 cm were subtracted and the size of the remaining tumour calculated. RESULTS: The maximum tumour diameters with a 30-mm parenchymal safety margin ranged from 26.1 mm in right-sided segments 7 + 8 to 59.8 mm in the left apical segments 1-3. CONCLUSIONS: Using a three-dimensional reconstruction of lung CT scans, we demonstrated that segmentectomy or resection of segmental groups should be feasible with adequate margins, even for larger tumours in selected cases.

Semi-automated volumetric analysis of lymph node metastases during follow-up--initial results.

OBJECTIVE: Quantification of tumour burden in oncology requires accurate and reproducible evaluation. The current standard is RECIST measurement with its inherent disadvantages. Volumetric analysis is an alternative for therapy monitoring. The aim of this study was to evaluate the feasibility of volumetric analysis of lymph node metastases using a software prototype in a follow-up setting. METHODS: MSCT was performed in 50 patients covering the chest, abdomen and pelvis. A total of 174 suspicious lymph nodes were evaluated by two radiologists regarding short axis diameters and volumetric analysis using semi-automated software. Quality of segmentation, time, maximum diameter and volume were documented. Variability of the derived change rates was computed as the standard deviation of the difference of the obtained respective change rates. RESULTS: The software performance provides robust volumetric analysis. Quality of segmentation was rated acceptable to excellent in 76-79% by each reader. Mean time spent per lesion was 38 s. The variability of change in effective diameters was 10.6%; for change rates of RECIST maximum diameter variability was 27.5%. CONCLUSION: Semi-automated volumetric analysis allows fast and convenient segmentation of most lymph node metastases. Compared with RECIST the inter-observer-variability in baseline and follow-up is reduced. This should principally allow subtle changes to be subclassified within the RECIST stable range as minor response [-15% to +10%].

[Three-dimensional reconstruction of central lung tumors based on CT data]. / Dreidimensionale Rekonstruktion von zentralen Lungentumoren basierend auf CT-Daten : Erste klinische Erfahrungen First clinical experiences.

BACKGROUND: CT scanning of the lungs is the standard procedure for preoperative evaluation of central lung tumors. The extent of the tumor and infiltration of central lung structures or lung segments are decisive parameters to clarify whether surgery is possible and the extent of resection. With computer-assisted methods for the segmentation of anatomical structures based on CT data (Fraunhofer MeVis, Bremen) an enhanced, three-dimensional selective visualization is now possible. PATIENTS AND METHODS: From August 2007 through June 2009, 22 patients with central lung tumors were treated at the department of thoracic surgery, University of Schleswig-Holstein, campus Lübeck. There were 15 males and 7 females with a mean age of 60.2 years (range 41-74 years), 18 patients had a long history of smoking, while 4 patients had never smoked. Of the patients 20 had a primary lung carcinoma, 1 patient had local recurrent lung cancer after lobectomy and 1 patient had a central lung metastasis from a non-pulmonary primary carcinoma. A multi-slice detector computer tomogram (MSDCT) scan was performed in all cases. All data were three-dimensionally reconstructed and visualized using special computer-aided software (Fraunhofer MeVis, Bremen). Pulmonary lung function tests, computed postoperative lung volume, bronchoscopic findings, general condition of the patients and the three-dimensionally reconstructed CT data were used for an individual risk analysis and surgical planning. RESULTS: According to the risk analysis 14 out of the 22 patients were surgically treated, 7 patients were staged as functionally inoperable and 1 as technically inoperable. A pneumonectomy was performed in 5 cases, a lobectomy/bilobectomy in 4 cases, an extended lobectomy in 3 cases and 1 case each of a wedge resection and a sleeve resection. Of the 14 patients 2 were classified as stage Ia/b, 7 patients as stage IIa/b and 5 patients as stage IIIa. The median length of time spent in hospital was 8.5±33 days and the mortality rate was 0%. The three-dimensional visualization of the tumor and its anatomical relationship to central pulmonary vessels and the airway system was feasible in all cases. The three-dimensional reconstruction was confirmed in all cases by surgical exploration. CONCLUSION: Three-dimensional reconstruction of CT scan data is a new and promising method for preoperative presentation and risk analysis of central lung tumors. The three-dimensional visualization with anatomical reformatting and color-coded segmentation enables the surgeon to make a more precise strategic approach for central lung tumors.

Computer-assisted quantification of interstitial lung disease associated with rheumatoid arthritis: preliminary technical validation.

PURPOSE: To validate a threshold-based prototype software application (MeVis PULMO 3D) for quantification of chronic interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA) using variable threshold settings for segmentation of diseased lung areas. METHODS: Twenty-two patients with rheumatoid arthritis were included and underwent thin-section CT (4x1.25mm collimation). CT scans were assessed by two observers for extent of ILD (EoILD), and twice by MeVis PULMO 3D for each protocol. MeVis PULMO 3D used four segmentation threshold (ST) settings (ST=-740, -780, -800 and -840HU). Pulmonary function tests were obtained in all patients. Statistical evaluation used 95% limits of agreement (LoA) and linear regression analysis. RESULTS: There was total concordance between the software measurements. Interobserver agreement was good (LoA=-28.36 to 17.58%). EoILD by readers correlated strongly with DL(CO) (r=-0.702, p<0.0001) and moderately with FVC (r=-0.523, p=0.018). There was close correlation between readers and MeVis PULMO 3D with best results for ST <780HU (EoILD vs. MeVis PULMO 3D: r=0.650 for ST=-800 and -840HU, respectively; p=0.002). MeVis PULMO 3D correlated best with DL(CO) at ST of -800HU (r=-0.44, -0.49, -0.58 and -0.57 for ST=-740, -780, -800 and -840, respectively; p=0.007-0.05) and moderately with FVC (r=-0.44, -0.51, -0.59 and -0.45 for ST=-740, -780, -800 and -840), respectively; p=0.007-0.05). CONCLUSION: The MeVis PULMO 3D system used holds promise to become a valuable instrument for quantification of chronic ILD in patients with RA when using the threshold value of -800HU, with evidence of the closest correlations, both with human observers and physiologic impairment.

Interstitial lung disease associated with collagen vascular disorders: disease quantification using a computer-aided diagnosis tool.

The purpose of this study was to evaluate a computer-aided diagnosis (CAD) tool compared to human observers in quantification of interstitial lung disease (ILD) in patients with collagen-vascular disorders. A total of 52 patients with rheumatoid arthritis (n=24), scleroderma (n=14) and systemic lupus erythematosus (n=14) underwent thin-section CT. Two independent observers assessed the extent of ILD (EoILD), reticulation (EoRet) and ground-glass opacity (EoGGO). CAD assessed EoILD twice. Pulmonary function tests were obtained. Statistical evaluation used 95% limits of agreement and linear regression analysis. CAD correlated well with diffusing capacity (DL(CO)) (R= -0.531, P<0.0001) and moderately with forced vital capacity (FVC) (R= -0.483, P=0.0008). There was close correlation between CAD and the readers (EoILD vs. CAD: R=0.716, P<0.0001; EoRet vs. CAD: R=0.69, P<0.0001). Subgroup analysis including patients with minimal EoGGO (<15%) strengthened the correlations between CAD and the readers, readers and PFT, and CAD and PFT. EoILD by readers correlated strongly with DL(CO) (R= -0.705, P<0.0001) and moderately with FVC (R= -0.559, P=0.0002). EoRet correlated closely with DL(CO) and moderately with FVC (DL(CO): R= -0.663; FVC: R = -0.436; P

Linear and volume measurements of pulmonary nodules at different CT dose levels - intrascan and interscan analysis.

PURPOSE: To compare the interobserver variability of the unidimensional diameter and volume measurements of pulmonary nodules in an intrascan and interscan analysis using semi-automated segmentation software on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT) data. MATERIALS AND METHODS: In 33 patients with pulmonary nodules, two chest multi-slice CT (MSCT) datasets (1 mm slice thickness; 20 % reconstruction overlap) had been consecutively acquired with an ultra-low dose (120 kV, 5 mAs) and standard dose technique (120 kV, 75 mAs). MSCT data was retrospectively analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany, version 1.3). The volume of 229 solid pulmonary nodules included in the analysis as well as the largest diameter according to RECIST (Response Evaluation Criteria for Solid Tumors) were measured by two radiologists. Interobserver variability was calculated and SD-CT and ULD-CT data compared in an intrascan and interscan analysis. RESULTS: The median nodule diameter (n = 229 nodules) was registered with 8.2 mm (range: 2.8 to 43.6 mm, mean: 10.8 mm). The nodule volume ranged between 0.01 and 49.1 ml (median 0.1 ml, mean 1.5 ml). With respect to interobserver variability, the intrascan analysis did not reveal statistically significant differences (p > 0.05) between ULD-CT and SD-CT with broader limits of agreement for relative differences of RECIST measurements (-31.0 % + 27.0 % mean -2.0 % for SD-CT; -27.0 % + 38.6 %, mean 5.8 % for ULD-CT) than for volume measurements (-9.4 %, 8.0 %, mean 0.7 % for SD-CT; -13 %, 13 %, mean 0.0 % for ULD-CT). The interscan analysis showed broadened 95 % confidence intervals for volume measurements (-26.5 % 29.1 % mean 1.3 %, and -25.2 %, 29.6 %, mean 2.2 %) but yielded comparable limits of agreement for RECIST measurements. CONCLUSION: The variability of nodule volumetry assessed by semi-automated segmentation software as well as nodule size determination by RECIST appears to be independent of the acquisition dose in the CT source dataset. This is particularly important regarding size determination of pulmonary nodules in screening trials using low-dose CT data for follow-up imaging.

[Automated pulmonary nodule volumetry with an optimized algorithm. Accuracy at different slice thicknesses compared to unidimensional and bidimensional measurements]. / Lungenrundherdvolumetrie mit optimiertem Segmentierungsalgorithmus. Genauigkeit bei verschiedenen Schichtdicken verglichen mit ein- und zweidimensionalen Messungen.

PURPOSE: This in-vivo study quantifies the accuracy of automated pulmonary nodule volumetry in reconstructions with different slice thicknesses (ST) of clinical routine CT scans. The accuracy of volumetry is compared to that of unidimensional and bidimensional measurements. MATERIALS AND METHODS: 28 patients underwent contrast enhanced 64-row CT scans of the chest and abdomen obtained in the clinical routine. All scans were reconstructed with 1, 3, and 5 mm ST. Volume, maximum axial diameter, and areas following the guidelines of Response Evaluation Criteria in Solid Tumors (RECIST) and the World Health Organization (WHO) were measured in all 101 lesions located in the overlap region of both scans using the new software tool OncoTreat (MeVis, Deutschland). The accuracy of quantifications in both scans was evaluated using the Bland and Altmann method. The reproducibility of measurements in dependence on the ST was compared using the likelihood ratio Chi-squared test. RESULTS: A total of 101 nodules were identified in all patients. Segmentation was considered successful in 88.1% of the cases without local manual correction which was deliberately not employed in this study. For 80 nodules all 6 measurements were successful. These were statistically evaluated. The volumes were in the range 0.1 to 15.6 ml. Of all 80 lesions, 34 (42%) had direct contact to the pleura parietalis oder diaphragmalis and were termed parapleural, 32 (40%) were paravascular, 7 (9%) both parapleural and paravascular, the remaining 21 (27%) were free standing in the lung. The trueness differed significantly (Chi-square 7.22, p value 0.027) and was best with an ST of 3 mm and worst at 5 mm. Differences in precision were not significant (Chi-square 5.20, p value 0.074). The limits of agreement for an ST of 3 mm were +/- 17.5 % of the mean volume for volumetry, for maximum diameters +/- 1.3 mm, and +/- 31.8 % for the calculated areas. CONCLUSION: Automated volumetry of pulmonary nodules using OncoTREAT has a conformable accuracy for an ST of 3 mm and 1 mm and is even more accurate for an ST of 5 mm than unidimensional or bidimensional measurements. A difference of more than +/- 17.5% occurs with a probability of less than 5% at an ST of 3 mm.

Semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma stage III/IV--a feasibility study.

Therapy monitoring in oncological patient care requires accurate and reliable imaging and post-processing methods. RECIST criteria are the current standard, with inherent disadvantages. The aim of this study was to investigate the feasibility of semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma compared to manual volumetric analysis and RECIST. Multislice CT was performed in 47 patients, covering the chest, abdomen and pelvis. In total, 227 suspicious, enlarged lymph nodes were evaluated retrospectively by two radiologists regarding diameters (RECIST), manually measured volume by placement of ROIs and semi-automated volumetric analysis. Volume (ml), quality of segmentation (++/--) and time effort (s) were evaluated in the study. The semi-automated volumetric analysis software tool was rated acceptable to excellent in 81% of all cases (reader 1) and 79% (reader 2). Median time for the entire segmentation process and necessary corrections was shorter with the semi-automated software than by manual segmentation. Bland-Altman plots showed a significantly lower interobserver variability for semi-automated volumetric than for RECIST measurements. The study demonstrated feasibility of volumetric analysis of lymph node metastases. The software allows a fast and robust segmentation in up to 80% of all cases. Ease of use and time needed are acceptable for application in the clinical routine. Variability and interuser bias were reduced to about one third of the values found for RECIST measurements.

Interobserver-variability of lung nodule volumetry considering different segmentation algorithms and observer training levels.

OBJECTIVE: The aim of this study was to investigate the interobserver variability of CT based diameter and volumetric measurements of artificial pulmonary nodules. A special interest was the consideration of different measurement methods, observer experience and training levels. MATERIALS AND METHODS: For this purpose 46 artificial small solid nodules were examined in a dedicated ex-vivo chest phantom with multislice-spiral CT (20 mAs, 120 kV, collimation 16 mm x 0.75 mm, table feed 15 mm, reconstructed slice thickness 1mm, reconstruction increment 0.7 mm, intermediate reconstruction kernel). Two observer groups of different radiologic experience (0 and more than 5 years of training, 3 observers each) analysed all lesions with digital callipers and 2 volumetry software packages (click-point depending and robust volumetry) in a semi-automatic and manually corrected mode. For data analysis the variation coefficient (VC) was calculated in per cent for each group and a Wilcoxon test was used for analytic statistics. RESULTS: Click-point robust volumetry showed with a VC of <0.01% in both groups the smallest interobserver variability. Between experienced and un-experienced observers interobserver variability was significantly different for diameter measurements (p=0.023) but not for semi-automatic and manual corrected volumetry. A significant training effect was revealed for diameter measurements (p=0.003) and semi-automatic measurements of click-point depending volumetry (p=0.007) in the un-experienced observer group. CONCLUSIONS: Compared to diameter measurements volumetry achieves a significantly smaller interobserver variance and advanced volumetry algorithms are independent of observer experience.

[Parametric biomedical imaging--what defines the quality of quantitative radiological approaches?]. / Parametrische biomedizinische Bildgebung--was macht die Qualität quantitativer radiologischer Verfahren aus?

Quantitative parametric imaging approaches provide new perspectives for radiological imaging. These include quantitative 2D, 3D, and 4D visualization options along with the parametric depiction of biological tissue properties and tissue function. This allows the interpretation of radiological data from a biochemical, biomechanical, or physiological perspective. Quantification permits the detection of small changes that are not yet visually apparent, thus allowing application in early disease diagnosis and monitoring therapy with enhanced sensitivity. This review outlines the potential of quantitative parametric imaging methods and demonstrates this on the basis of a few exemplary applications. One field of particular interest, the use of these methods for investigational new drug application studies, is presented. Assessment criteria for judging the quality of quantitative imaging approaches are discussed in the context of the potential and the limitations of these methods. While quantitative parametric imaging methods do not replace but rather supplement established visual interpretation methods in radiology, they do open up new perspectives for diagnosis and prognosis and in particular for monitoring disease progression and therapy.

[CT-based software-supported prediction of the postoperative lung function after partial resection of the lung]. / CT-basierte softwaregestützte Vorhersage der postoperativen Lungenfunktion nach Lungenteilresektion.

PURPOSE: The predicted postoperative forced exspiratory volume in one second (FEV (1)) is an important functional factor for predicting the operability of patients with bronchial carcinoma. A software tool that uses a preoperative chest MSCT and pulmonary function test (PFT) for largely automated prediction of the FEV (1) was evaluated. MATERIALS AND METHODS: Fifteen patients with surgically treated lung cancer were examined with a preoperative chest MSCT (1.25 mm slice thickness, 0.8 mm reconstruction increment) and PFT before and after surgery. CT scans were analyzed by the prototype software MeVisPulmo (MeVis gGmbH, Bremen) that predicted the postoperative FEV (1) as a percentage of the preoperative values measured by PFT. The automated segmentation and volumetry of lung lobes were performed either without or with minimal user interaction. Patients underwent lobectomy in twelve cases (6 upper lobes, 1 middle lobe, 5 lower lobes) and pneumectomy in three cases. The predicted FEV (1) values were compared to the observed postoperative values as a standard of reference. The additional functional parameters "total lung capacity" (TLC) and "forced vital capacity" (FVC) were compared to the FEV (1) results. RESULTS: Automated calculation of predicted postoperative lung function was successful in all cases. Due to an implausible PFT, two of the 15 patients were excluded from the collective. A mean postoperative FEV (1) value of 75 % (SD +/- 12 %) of the preoperative FEV (1) was calculated and 74 % (SD +/- 12 %) was actually measured. The deviations of the predicted value from the measured postoperative FEV (1) ranged between - 289 ml (-12 % of the measured postoperative FEV (1)) and + 294 ml (+ 15 % of the postoperative FEV (1)). The mean deviation (absolute value) was 137 +/- 77 ml/s. This corresponds to 7 +/- 3 % of the measured postoperative FEV (1). Bland-Altman-Statistics showed the 95 % "limits of agreement" for the predicted FEV (1) values to be between - 341 ml and + 301 ml, corresponding to - 17.5 % and + 15.8 of the measured postoperative FEV (1) value. Analysis of the TLC and FVC yielded similar results. CONCLUSION: In the present pilot study the software-assisted prediction of the postoperative FEV (1) using a preoperative MSCT and pulmonary function test corresponded satisfactorily with the observed postoperative values. The introduced approach may make it possible to obtain additional information for the prediction of functional operability prior to performing lung cancer surgery.