Semi-automated quantification of hepatic lesions in a phantom

Variability of quantitative measurements of metastatic liver lesions: a multi-radiation-dose-level and multi-reader comparison

PURPOSE

To evaluate the variability of quantitative measurements of metastatic liver lesions by using a multi-radiation-dose-level and multi-reader comparison.

METHODS

Twenty-three study subjects (mean age, 60 years) with 39 liver lesions who underwent a single-energy dual-source contrast-enhanced staging CT between June 2015 and December 2015 were included. CT data were reconstructed with seven different radiation dose levels (ranging from 25 to 100%) on the basis of a single CT acquisition. Four radiologists independently performed manual tumor measurements and two radiologists performed semi-automated tumor measurements. Interobserver, intraobserver, and interdose sources of variability for longest diameter and volumetric measurements were estimated and compared using Wilcoxon rank-sum tests and intraclass correlation coefficients.

RESULTS

Inter- and intraobserver variabilities for manual measurements of the longest diameter were higher compared to semi-automated measurements (p < 0.001 for overall). Inter- and intraobserver variabilities of volume measurements were higher compared to the longest diameter measurement (p < 0.001 for overall). Quantitative measurements were statistically different at < 50% radiation dose levels for semi-automated measurements of the longest diameter, and at 25% radiation dose level for volumetric measurements. The variability related to radiation dose was not significantly different from the inter- and intraobserver variability for the measurements of the longest diameter.

CONCLUSION

The variability related to radiation dose is comparable to the inter- and intraobserver variability for measurements of the longest diameter. Caution should be warranted in reducing radiation dose level below 50% of a conventional CT protocol due to the potentially detrimental impact on the assessment of lesion response in the liver.

The Technome - A Predictive Internal Calibration Approach for Quantitative Imaging Biomarker Research

The goal of radiomics is to convert medical images into a minable data space by extraction of quantitative imaging features for clinically relevant analyses, e.g. survival time prediction of a patient. One problem of radiomics from computed tomography is the impact of technical variation such as reconstruction kernel variation within a study. Additionally, what is often neglected is the impact of inter-patient technical variation, resulting from patient characteristics, even when scan and reconstruction parameters are constant. In our approach, measurements within 3D regions-of-interests (ROI) are calibrated by further ROIs such as air, adipose tissue, liver, etc. that are used as control regions (CR). Our goal is to derive general rules for an automated internal calibration that enhance prediction, based on the analysed features and a set of CRs. We define qualification criteria motivated by status-quo radiomics stability analysis techniques to only collect information from the CRs which is relevant given a respective task. These criteria are used in an optimisation to automatically derive a suitable internal calibration for prediction tasks based on the CRs. Our calibration enhanced the performance for centrilobular emphysema prediction in a COPD study and prediction of patients' one-year-survival in an oncological study.

Volumetric Versus Unidimensional Measures of Metastatic Colorectal Cancer in Assessing Disease Response

INTRODUCTION

The purpose of this study was to compare unidimensional (1D/linear) and volumetric (3D) measures of metastatic colorectal cancer (mCRC) at computed tomography (CT) for predicting clinical outcome.

PATIENTS AND METHODS

Analysis of CT images in 105 patients (mean age, 59 years; range, 25-81 years; 45 women, 60 men) receiving treatment for mCRC was performed. Both unidimensional and volumetric measures were obtained on index lesions at 3 time points (baseline/midpoint/post-therapy; mean interval, 4.1 months; median, 3.7 months) by 3 readers using a semi-automated technique. Measurements were summed and compared using best overall response across the 3 time points. Patient response was categorized based on Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 thresholds for unidimensional and volume measures (CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease). Survival data was correlated (mean follow-up, 19.9 ± 17.1 months; median, 14.7 months). Intra/interobserver variability and reproducibility of 1D and 3D measures was assessed. Cox survival and Kaplan-Meier models were constructed and compared.

RESULTS

Cox models and Kaplan-Meier curves for unidimensional versus volumetric assessment were very similar in appearance. Both 1D and 3D measurements effectively separated PD from the SD/PR groups, but neither separated SD from PR well. Volumetric measures showed comparable intra/interobserver variability on Bland-Altman analysis to unidimensional measures across readers using a semi-automated measurement technique. Metastatic site (lung, liver, node, other) did not seem to impact measurement reproducibility.

CONCLUSIONS

Although CT volumetric assessment of metastatic colorectal cancer is fairly reproducible by reader and site using a semi-automated technique, the ability to stratify progressive disease from other disease response categories in terms of survival was similar to unidimensional measurement.

Volumes Learned: It Takes More Than Size to "Size Up" Pulmonary Lesions

RATIONALE AND OBJECTIVES

This study aimed to review the current understanding and capabilities regarding use of imaging for noninvasive lesion characterization and its relationship to lung cancer screening and treatment.

MATERIALS AND METHODS

Our review of the state of the art was broken down into questions about the different lung cancer image phenotypes being characterized, the role of imaging and requirements for increasing its value with respect to increasing diagnostic confidence and quantitative assessment, and a review of the current capabilities with respect to those needs.

RESULTS

The preponderance of the literature has so far been focused on the measurement of lesion size, with increasing contributions being made to determine the formal performance of scanners, measurement tools, and human operators in terms of bias and variability. Concurrently, an increasing number of investigators are reporting utility and predictive value of measures other than size, and sensitivity and specificity is being reported. Relatively little has been documented on quantitative measurement of non-size features with corresponding estimation of measurement performance and reproducibility.

CONCLUSIONS

The weight of the evidence suggests characterization of pulmonary lesions built on quantitative measures adds value to the screening for, and treatment of, lung cancer. Advanced image analysis techniques may identify patterns or biomarkers not readily assessed by eye and may also facilitate management of multidimensional imaging data in such a way as to efficiently integrate it into the clinical workflow.

Inter-Method Performance Study of Tumor Volumetry Assessment on Computed Tomography Test-Retest Data

RATIONALE AND OBJECTIVES

Tumor volume change has potential as a biomarker for diagnosis, therapy planning, and treatment response. Precision was evaluated and compared among semiautomated lung tumor volume measurement algorithms from clinical thoracic computed tomography data sets. The results inform approaches and testing requirements for establishing conformance with the Quantitative Imaging Biomarker Alliance (QIBA) Computed Tomography Volumetry Profile.

MATERIALS AND METHODS

Industry and academic groups participated in a challenge study. Intra-algorithm repeatability and inter-algorithm reproducibility were estimated. Relative magnitudes of various sources of variability were estimated using a linear mixed effects model. Segmentation boundaries were compared to provide a basis on which to optimize algorithm performance for developers.

RESULTS

Intra-algorithm repeatability ranged from 13% (best performing) to 100% (least performing), with most algorithms demonstrating improved repeatability as the tumor size increased. Inter-algorithm reproducibility was determined in three partitions and was found to be 58% for the four best performing groups, 70% for the set of groups meeting repeatability requirements, and 84% when all groups but the least performer were included. The best performing partition performed markedly better on tumors with equivalent diameters greater than 40 mm. Larger tumors benefitted by human editing but smaller tumors did not. One-fifth to one-half of the total variability came from sources independent of the algorithms. Segmentation boundaries differed substantially, not ony in overall volume but also in detail.

CONCLUSIONS

Nine of the 12 participating algorithms pass precision requirements similar to what is indicated in the QIBA Profile, with the caveat that the present study was not designed to explicitly evaluate algorithm profile conformance. Change in tumor volume can be measured with confidence to within ±14% using any of these nine algorithms on tumor sizes greater than 10 mm. No partition of the algorithms was able to meet the QIBA requirements for interchangeability down to 10 mm, although the partition comprising best performing algorithms did meet this requirement for a tumor size of greater than approximately 40 mm.

Volumetric evaluation of hepatic tumors: multi-vendor, multi-reader liver phantom study

PURPOSE

To compare liver lesion volume measurement on multiple 3D software platforms using a liver phantom.

METHODS

An anthropomorphic phantom constructed with ten liver lesions of varying size, attenuation, and shape with known volume and long axis measurement was scanned (120 kVp, 80-440 smart mA, NI 12). DICOM data were uploaded to five commercially available 3D visualization systems and manual tumor volume was obtained by three-independent readers. Accuracy and reproducibility of linear and volume measurements were compared. The two most promising systems were then compared with an additional prototype system by two readers using both manual and semi-automated measurement with similar comparison between linear and volume measures. Measurements were performed on 5- and 1.25-mm data sets. Inter- and intra-observer variability was also assessed.

RESULTS

Overall mean % volume error on the five commercially available software systems (averaging all ten liver lesions among all three readers) was 8.0% ± 7.5%, 13.7% ± 11.2%, 14.2% ± 15.2%, 16.4% ± 14.8 %, and 16.9% ± 13.8%, varying almost twofold across vendor. Moderate inter-observer variability was present. Volume measurement was slightly more accurate than linear measurement, but linear measurement was more reproducible across readers and systems. On the two "best" systems, the manual measurement method was more accurate than the automated method (p = 0.001). The prototype system demonstrated superior semi-automated assessment, with a mean % volume error of 5.3% ± 4.1% (vs. 17.8% ± 11.1% and 31.5% ± 19.7%, p < 0.001), with improved inter- and intra-observer variability.

CONCLUSIONS

Accuracy and reproducibility of volume assessment of liver lesions varies significantly by vendor, which has important implications for clinical use.

Tumor growth kinetics versus RECIST to assess response to locoregional therapy in breast cancer liver metastases

RATIONALE AND OBJECTIVES

The aim of our study was to evaluate changes in growth kinetics of breast cancer liver metastasis in response to locoregional therapy and compare them to Response Evaluation Criteria in Solid Tumors (RECIST).

MATERIALS AND METHODS

This Health Insurance Portability and Accountability Act-compliant retrospective study was Institutional Review Board approved. Thirty-four chemorefractory breast cancer liver metastases from 21 patients treated with yttrium-90 ((90)Y) were evaluated. Pre- and posttreatment computed tomography (CT) scans were used to calculate tumor growth kinetics. The growth parameter analyzed was reciprocal of doubling time (RDT). RDT range for stable disease (SD) was defined by the measurement error rate. A negative RDT below the SD range defined response and was categorized as either partial response (PR) or complete response, whereas a positive RDT value above the SD range indicated progressive disease (PD). Comparison was made to tumor response classification according to percentage change in the lesion's maximal diameter per RECIST. Lin's concordance correlation coefficient, Bland-Altman plot, Wilcoxon signed rank test, and Student t test were used for analysis. Significance was set at 0.05.

RESULTS

RDT range for SD ranged from -0.46 to +2.17. Six lesions with PR based on RECIST showed PR based on their volumetric growth rate (mean RDT of -17.3 ± 2.6). Similarly, one lesion with PD according to RECIST was categorized as PD based on its growth kinetics (RDT of 10.2). However, 14 (51.85%) lesions classified as SD by RECIST had PR according to growth kinetics (mean RDT of -7.8), six (22.22%) lesions were categorized as SD (mean RDT of 0.8), whereas seven (25.93%) lesions showed PD (mean RDT of 4.5). Growth kinetic parameters were significantly different for lesions with PR when compared to lesions with PD (P < .0001).

CONCLUSIONS

In patients with breast cancer liver metastases undergoing locoregional therapy, RECIST categorization may not be an accurate reflection of treatment response.

Impact of slice thickness on semi-automated measurements for volume and whole-tumor attenuation of colorectal hepatic metastases in multislice computed tomography

BACKGROUND

Volumetric and whole-tumor attenuation assessment of tumor are of value in assessment of treatment.

PURPOSE

To assess the impact of slice thickness on semi-automatic analyses (volume, whole-tumor attenuation) for small colorectal hepatic metastases.

MATERIAL AND METHODS

Computed tomography (CT) data of patients with colorectal hepatic metastases at 1.5-, 3-, and 5-mm slice thickness were semi-automatically evaluated for volume and whole-tumor attenuation by two radiologists independently. Statistical analysis included paired samples t-test and concordance correlation coefficient (CCC) analysis according to the longest axial tumor diameter (10-20 mm, 20-30 mm, 30-40 mm).

RESULTS

A total of 62 patients (32 men and 30 women) with 62 target tumors were included. The mean volume was significantly higher at 3- and 5-mm slice thicknesses in comparison with the reference (1.5 mm) for the target tumors between 10 mm and 20 mm (P = 0.0295, CCC = 0.9394 for 3 mm; P = 0.0029, CCC = 0.5129 for 5 mm, respectively) and at 5 mm slice thickness for the target tumors between 20 mm and 30 mm (P = 0.0071, CCC = 0.9102). For whole-tumor attenuation measurements, the significant difference was only seen at 5-mm slice thicknesses in comparison with the reference (1.5 mm) for the target tumors between 10 and 20 mm (P = 0.0015, CCC = 0.9389).

CONCLUSION

Slice thickness of 1.5 mm might be suggested for semi-automated volumetric measurements, and slice thickness of no more than 3 mm for whole-tumor CT attenuation in hepatic metastasis between 10 mm and 20 mm.

Quantitative and volumetric European Association for the Study of the Liver and Response Evaluation Criteria in Solid Tumors measurements: feasibility of a semiautomated software method to assess tumor response after transcatheter arterial chemoembolization

PURPOSE

To show that hepatic tumor volume and enhancement pattern measurements can be obtained in a time-efficient and reproducible manner on a voxel-by-voxel basis to provide a true three-dimensional (3D) volumetric assessment.

MATERIALS AND METHODS

Magnetic resonance (MR) imaging data obtained from 20 patients recruited for a single-institution prospective study were retrospectively evaluated. All patients had a diagnosis of hepatocellular carcinoma (HCC) and underwent drug-eluting beads (DEB) transcatheter arterial chemoembolization for the first time. All patients had undergone contrast-enhanced MR imaging before and after DEB transcatheter arterial chemoembolization; poor image quality excluded 3 patients, resulting in a final count of 17 patients. Volumetric RECIST (vRECIST) and quantitative EASL (qEASL) were measured, and segmentation and processing times were recorded.

RESULTS

There were 34 scans analyzed. The time for semiautomatic segmentation was 65 seconds±33 (range, 40-200 seconds). vRECIST and qEASL of each tumor were computed<1 minute for each.

CONCLUSIONS

Semiautomatic quantitative tumor enhancement (qEASL) and volume (vRECIST) assessment is feasible in a workflow-efficient time frame. Clinical correlation is necessary, but vRECIST and qEASL could become part of the assessment of intraarterial therapy for interventional radiologists.

Tumor volume as an alternative response measurement for imatinib treated GIST patients

Background

Assessment of tumor size changes is crucial in clinical trials and patient care. We compared imatinib-induced volume changes of liver metastases (LM) from gastro-intestinal stromal tumors (GIST) to RECIST and Choi criteria and their association with overall survival (OS).

Methods

LM from 84 GIST patients (training and validation set) were evaluated using manual and semi-automated Computed Tomography measurements at baseline, after 3, 6 and 12 months of imatinib. The ability of uni-dimensional (1D) and three-dimensional (3D) measurements to detect size changes (increase/decrease) ≥20% was evaluated. Volumetric response cut-offs were derived from minimally relevant changes (+20/−30%) by RECIST, considering lesions as spherical or ellipsoidal.

Results

3D measurements detected size changes ≥20% more frequently than 1D at every time-point (P≤0.008). 3D and Choi criteria registered more responses than RECIST at 3 and 6 months for 3D-spheres (P≤0.03) and at all time-points for 3D-ellipsoids and Choi criteria (P<0.001). Progressive disease by 3D criteria seems to better correlate to OS at late time-points than other criteria.

Conclusion

Volume criteria (especially ellipsoids) classify a higher number of patients as imatinib-responders than RECIST. Volume discriminates size changes better than diameter in GIST and constitutes a feasible and robust method to evaluate response and predict patient benefit.

Soft tissue bleeding associated with antithrombotic treatment: technical and clinical outcomes after transcatheter embolization

PURPOSE

To assess retrospectively technical and clinical outcomes after transcatheter embolization in patients presenting with soft tissue bleeding associated with antithrombotic therapy and to determine factors potentially affecting the clinical outcomes after embolization.

MATERIALS AND METHODS

There were 42 patients who underwent embolization for soft tissue bleeding associated with antithrombotic therapy. Principal clinical symptoms were hemodynamic shock (n = 21), abdominal pain (n = 9), back pain (n = 7), and buttock or thigh pain (n = 5). Ultrasound or computed tomography (CT) or both were performed in 40 patients (95%); 2 patients (5%) were immediately referred for angiography. Several laboratory and radiographic factors were analyzed to determine if any influenced the clinical outcome.

RESULTS

A hematoma was identified in the anterior abdominal wall (n = 18 [43%]), in the retroperitoneum (n = 18 [43%]), or in the thigh or gluteal region (n = 6 [14%]). Embolization was successful in all patients; early recurrent bleeding with a fatal outcome was recorded in one patient (2%). In nine patients (22%), secondary surgical drainage of the hematoma was performed to manage a compartment syndrome. During follow-up (mean, 37.9 months; range, 0.03-85.28 months), 11 patients (26%) died; death was related to the bleeding in 6 patients (14%). Both activated partial thromboplastin time (aPTT) and prothrombin time (PT) were correlated with hematoma size. Prolonged aPTT before embolization was associated with a higher risk of bleeding-related mortality (P = .04).

CONCLUSIONS

Transcatheter embolization was very effective in stopping soft tissue bleeding associated with antithrombotic therapy. However, there was still considerable morbidity and mortality after successful embolization. aPTT prolongation emerged as a risk factor for bleeding-related deaths.

Hepatic tumors: region-of-interest versus volumetric analysis for quantification of attenuation at CT

PURPOSE

To evaluate the reproducibility of liver tumor attenuation measurement performed by using the routinely used manual region-of-interest (ROI) method and that of measurement performed by using a semiautomated volumetric approach at computed tomography (CT).

MATERIALS AND METHODS

This HIPAA-compliant retrospective study had institutional review board approval. The requirement for patient informed consent was waived. Attenuation of colon cancer liver metastases in 208 patients was measured on portal venous phase multidetector CT images by using a single ROI, the average measurement in three ROIs on a single section, and with semiautomated segmentation of the entire tumor volume (volumetric attenuation) to evaluate intermethod agreement. Intraobserver and interobserver reproducibility were evaluated in the first 70 patients. Measurements were repeated after 30 days to assess intraobserver reproducibility. Differences between methods were tested by using repeated-measures analysis of variance. Intermethod, intraobserver, and interobserver agreements were tested by using Bland-Altman analysis and the Lin concordance correlation coefficient (ρc). P < .05 was considered to indicate a significant difference.

RESULTS

A total of 208 pathologically proven colon cancer hepatic metastases larger than 20 mm in diameter in 100 women and 108 men (mean age, 61.6 years ± 11.6 [standard deviation]; range, 28-87 years) were evaluated. Attenuation was significantly different between the three methods of measurement (P < .001 for all). Volumetric measurements had better intraobserver agreement (precision = 3.3%, ρc = 0.996, P < .001) than single-ROI measurements (precision = 12.0%, ρc = 0.947, P < .001) and measurements averaged over three ROIs (precision = 9.3%, ρc = 0.965, P < .001). Volumetric measurements also had better interobserver agreement (precision = 3.6%, ρc = 0.993, P < .001) than single-ROI measurements (precision = 11.3%, ρc = 0.957, P < .001) and the average measurement in three ROIs (precision = 8.5%, ρc = 0.976, P < .001).

CONCLUSION

Measurements of hepatic tumor attenuation at multidetector CT are reproducible. An approach based on the evaluation of whole-lesion attenuation demonstrated better reproducibility than ROI measurements.

Intra- and inter-observer variability in measurement of target lesions: implication on response evaluation according to RECIST 1.1

Background

The assessment of cancer treatment in oncological clinical trials is usually based on serial measurements of tumours’ size according to the Response Evaluation Criteria in Solid Tumours (RECIST) guidelines. The aim of our study was to evaluate the variability of measurements of target lesions by readers as well as the impact on response evaluation, workflow and reporting.

Patients and methods

Twenty oncologic patients were included to the study with CT examinations from thorax to pelvis performed at a 64 slices CT scanner. Four readers defined and measured the size of target lesions independently at baseline and follow-up with PACS (Picture Archiving and Communication System) and LMS (Lesion Management Solutions, Median technologies, Valbonne Sophia Antipolis, France), according to the RECIST 1.1 criteria. Variability in measurements using PACS or LMS software was established with the Bland and Altman approach. The inter- and intra-observer variabilities were calculated for identical lesions and the overall response per case was determined. In addition, time required for evaluation and reporting in each case was recorded.

Results

For single lesions, the median intra-observer variability ranged from 4.9–9.6% (mean 5.9%) and the median inter-observer variability from 4.3–11.4% (mean 7.1%), respecting different evaluation time points, image systems and observers. Nevertheless, the variability in change of Δ sum longest diameter (LD), mandatory for classification of the overall response, was 24%. The overall response evaluation assessed by a single respectively different observer was discrepant in 6.3% respectively 12% of the cases compared with the mean results of multiple observers. The mean case evaluation time was 286s vs. 228s at baseline and 267s vs. 196s at follow-up for PACS and LMS, respectively.

Conclusions

Uni-dimensional measurements of target lesions show low intra- and inter-observer variabilities, but the high variability in change of Δ sum LD shows the potential for misclassification of the overall response according to the RECIST 1.1 guidelines. Nevertheless, the reproducibility of RECIST reporting can be improved for the case assessment by a single observer and by mean results of multiple observers. Case-based evaluation time was shortened up to 27% using custom software.

Preclinical multimodality phantom design for quality assurance of tumor size measurement

BACKGROUND

Evaluation of changes in tumor size from images acquired by ultrasound (US), computed tomography (CT) or magnetic resonance imaging (MRI) is a common measure of cancer chemotherapy efficacy. Tumor size measurement based on either the World Health Organization (WHO) criteria or the Response Evaluation Criteria in Solid Tumors (RECIST) is the only imaging biomarker for anti-cancer drug testing presently approved by the United States Food and Drug Administration (FDA). The aim of this paper was to design and test a quality assurance phantom with the capability of monitoring tumor size changes with multiple preclinical imaging scanners (US, CT and MRI) in order to facilitate preclinical anti-cancer drug testing.

METHODS

Three phantoms (Gammex/UTHSCSA Mark 1, Gammex/UTHSCSA Mark 2 and UTHSCSA multimodality tumor measurement phantom) containing tumor-simulating test objects were designed and constructed. All three phantoms were scanned in US, CT and MRI devices. The size of test objects in the phantoms was measured from the US, CT and MRI images. RECIST, WHO and volume analyses were performed.

RESULTS

The smaller phantom size, simplified design and better test object CT contrast of the UTHSCSA multimodality tumor measurement phantom allowed scanning of the phantom in preclinical US, CT and MRI scanners compared with only limited preclinical scanning capability of Mark 1 and Mark 2 phantoms. For all imaging modalities, RECIST and WHO errors were reduced for UTHSCSA multimodality tumor measurement phantom (≤1.69 ± 0.33%) compared with both Mark 1 (≤ -7.56 ± 6.52%) and Mark 2 (≤ 5.66 ± 1.41%) phantoms. For the UTHSCSA multimodality tumor measurement phantom, measured tumor volumes were highly correlated with NIST traceable design volumes for US (R2 = 1.000, p < 0.0001), CT (R2 = 0.9999, p < 0.0001) and MRI (R2 = 0.9998, p < 0.0001).

CONCLUSIONS

The UTHSCSA multimodality tumor measurement phantom described in this study can potentially be a useful quality assurance tool for verifying radiologic assessment of tumor size change during preclinical anti-cancer therapy testing with multiple imaging modalities.

Response to treatment series: part 2, tumor response assessment--using new and conventional criteria

OBJECTIVE

Conventional anatomic imaging biomarkers, including World Health Organization (WHO) criteria and Response Evaluation Criteria in Solid Tumors (RECIST), although effective, have limitations. This article will discuss the conventional and newer morphologic imaging biomarkers for the assessment of tumor response to therapy.

CONCLUSION

Applying established methods of assessing tumor response to therapy allows consistency in image interpretation and facilitates communication with oncologists. Because of the new methods of treatment, assessment of necrosis and volumetric information will need to be incorporated into size-based criteria.

Hepatocellular carcinoma: response to TACE assessed with semiautomated volumetric and functional analysis of diffusion-weighted and contrast-enhanced MR imaging data

PURPOSE

To determine the association of early changes in posttreatment apparent diffusion coefficient (ADC) and venous enhancement (VE) with tumor size change after transarterial chemoembolization (TACE) by using an investigational semiautomated software.

MATERIALS AND METHODS

This retrospective HIPAA-compliant study was approved by the institutional review board, with waiver of informed consent. Patients underwent magnetic resonance (MR) imaging at 1.5 T before TACE, as well as 1 and 6 months after TACE. Volumetric analysis of change in ADC and VE 1 month after TACE compared with pretreatment values was performed in 48 patients with 71 hepatocellular carcinoma (HCC) lesions. Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) analysis, using tumor response at 6 months according to Response Evaluation Criteria in Solid Tumors (RECIST) and modified RECIST as end points.

RESULTS

According to RECIST criteria, 6 months after TACE, 30 HCC lesions showed partial response (PR), 35 showed stable disease (SD), and six showed progressive disease (PD). Increase in ADC and decrease in VE 1 month after TACE were significantly different between PR, SD, and PD. At area under the ROC curve (AUC) analysis of the ADC increase, there was an AUC of 0.78 for distinguishing PR from SD and PD and an AUC of 0.89 for distinguishing PR and SD from PD. The AUC for decrease in VE was 0.73 for discrimination of PR from SD and PD and 0.90 for discrimination of PR and SD from PD.

CONCLUSION

Volumetric analysis of increase in ADC and decrease in VE 1 month after TACE can provide an early assessment of response to treatment. Volumetric analysis of multiparametric MR imaging data may have potential as a prognostic biomarker for patients undergoing local-regional treatment of liver cancer.

Comparison of semiautomated and manual measurements for simulated hypo- and hyper-attenuating hepatic tumors on MDCT: effect of slice thickness and reconstruction increment on their accuracy

RATIONALE AND OBJECTIVES

The aims of this study were to compare accuracy between semiautomated and manual measurements of the longest diameter and volume of simulated hepatic tumors in phantoms and to evaluate the effects of slice thickness (ST) and reconstruction increment (RI) on accuracy.

MATERIALS AND METHODS

Liver phantoms with 45 hypoattenuating and 45 hyperattenuating lesions of different sizes (diameter, 13.3-50.7 mm; volume, 0.4-54.0 mm(3)) and shapes (spherical or elliptical) were scanned using a 64-row multidetector computed tomographic scanner. Images were reconstructed with ST and RI settings of 0.75 and 0.7 mm, 1.0 and 0.7 mm, 1.5 and 1.0 mm, 3.0 and 2.0 mm, 3.0 and 3.0 mm, and 5.0 and 5.0 mm. The longest diameter and volume of each lesion were measured both manually and semiautomatically. To assess accuracy, measurements were compared to reference values by calculating absolute percentage error. Comparisons of absolute percentage error between methods and between ST and RI settings were performed using paired t tests. The degree of correlation between each measurement and a reference value was also assessed.

RESULTS

The semiautomated method showed significantly higher accuracy than the manual method in volume for most ST and RI settings (0.75 and 0.7 mm, 1.0 and 0.7 mm, and 1.5 and 1.0 mm in hypoattenuating lesions and all settings in hyperattenuating lesions; P < .05) and showed similar accuracy in diameter for all ST and RI settings regardless of lesion attenuation (P > .05). Semiautomated measurements also demonstrated higher correlation with reference values than the manual method for both diameter and volume. The absolute percentage error tended to be increased as ST and RI increased for both methods, and acceptable maximum ST and RI in semiautomated method were 1.5 and 1.0 mm.

CONCLUSIONS

Semiautomated computed tomographic measurement showed higher accuracy and correlation than the manual method in measuring the diameter and volume of hepatic lesions. The accuracy of both methods was highly dependent on z-axis resolution.

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.

Morphological and functional MDCT: problem-solving tool and surrogate biomarker for hepatic disease clinical care and drug discovery in the era of personalized medicine

This article explains the significant role of morphological and functional multidetector computer tomography (MDCT) in combination with imaging postprocessing algorithms served as a problem-solving tool and noninvasive surrogate biomarker to effectively improve hepatic diseases characterization, detection, tumor staging and prognosis, therapy response assessment, and novel drug discovery programs, partial liver resection and transplantation, and MDCT-guided interventions in the era of personalized medicine. State-of-the-art MDCT depicts and quantifies hepatic disease over conventional CT for not only depicting lesion location, size, and extent but also detecting changes in tumor biologic behavior caused by therapy or tumor progression before morphologic changes. Color-encoded parameter display provides important functional information on blood flow, permeability, leakage space, and blood volume. Together with other relevant biomarkers and genomics, the imaging modality is being developed and validated as a biomarker to early response to novel, targeted anti-VEGF(R)/PDGFR or antivascular/angiogenesis agents as its parameters correlate with immunohistochemical surrogates of tumor angiogenesis and molecular features of malignancies. MDCT holds incremental value to World Health Organization response criteria and Response Evaluation Criteria in Solid Tumors in liver disease management. MDCT volumetric measurement of future remnant liver is the most important factor influencing the outcome of patients who underwent partial liver resection and transplantation. MDCT-guided interventional methods deliver personalized therapies locally in the human body. MDCT will hold more scientific impact when it is fused with other imaging probes to yield comprehensive information regarding changes in liver disease at different levels (anatomic, metabolic, molecular, histologic, and other levels).