Tumor size on computed tomography scans

Simplifying Tumor Volume Estimation from Linear Dimensions for Intra-Cranial Lesions Treated with Stereotactic Radiosurgery

Aims:

This study aims to derive simple yet robust formula(s) for the calculation of cranial tumor volume using linear tumor dimensions in anterioposterior (AP), mediolateral (ML) and craniocaudal (CC) directions and also propose a reproducible methodology for tumor dimension measurements.

Materials and Methods:

Magnetic resonance images (MRI) of 337 patients planned for Gammaknife Stereotactic Radiosurgery for different types of brain tumors were analyzed using Leksell Gamma Plan (LGP) software. Tumor volume in three dimensional was outlined and maximum tumor diameters were measured in three orthogonal directions AP, ML, and CC on the MRI. Formulas were derived to calculate tumor volume from AP, ML, and CC diameters using linear regression technique. An agreement between the calculated volume and standard volume observed from LGP software was determined using Bland Altman (B-A) plot. A comparison was made between the volume calculated using traditionally used formula of ellipsoid, standard volume obtained from LGP software and volume calculated from formulas derived in the present study.

Results:

The tumors were divided into two categories based on their size for better volume prediction. The tumors having product of their diameters in the range 0–2.5cc were called “small tumors” and the formula proposed for their volume estimation (V = 1.513) × (AP × ML × CC) + 0.047 ) was found to predict the tumor volume with an average bias of 0.0005cc. For “large tumors,” having product of diameters in the range 2.5–36cc, the proposed formula (V = 0.444 × (AP × ML × CC) + 0.339 ) predicted the tumor volume with an average bias of 0.007cc.

Conclusions:

The two formulas proposed in the study are more accurate as compared to the commonly used formula that considers the tumors as ellipsoids. The methodology proposed in the study for measurement of linear tumor dimensions is simple and reproducible.

Effects of laparoscopy, laparotomy, and respiratory phase on liver volume in a live porcine model for liver resection

Background

Hepatectomy, living donor liver transplantations and other major hepatic interventions rely on precise calculation of the total, remnant and graft liver volume. However, liver volume might differ between the pre- and intraoperative situation. To model liver volume changes and develop and validate such pre- and intraoperative assistance systems, exact information about the influence of lung ventilation and intraoperative surgical state on liver volume is essential.

Methods

This study assessed the effects of respiratory phase, pneumoperitoneum for laparoscopy, and laparotomy on liver volume in a live porcine model. Nine CT scans were conducted per pig (N = 10), each for all possible combinations of the three operative (native, pneumoperitoneum and laparotomy) and respiratory states (expiration, middle inspiration and deep inspiration). Manual segmentations of the liver were generated and converted to a mesh model, and the corresponding liver volumes were calculated.

Results

With pneumoperitoneum the liver volume decreased on average by 13.2% (112.7 ml ± 63.8 ml, p < 0.0001) and after laparotomy by 7.3% (62.0 ml ± 65.7 ml, p = 0.0001) compared to native state. From expiration to middle inspiration the liver volume increased on average by 4.1% (31.1 ml ± 55.8 ml, p = 0.166) and from expiration to deep inspiration by 7.2% (54.7 ml ± 51.8 ml, p = 0.007).

Conclusions

Considerable changes in liver volume change were caused by pneumoperitoneum, laparotomy and respiration. These findings provide knowledge for the refinement of available preoperative simulation and operation planning and help to adjust preoperative imaging parameters to best suit the intraoperative situation.

CT-scan findings of COVID-19 pneumonia based on the time elapsed from the beginning of symptoms to the CT imaging evaluation: a descriptive study in Iran

Background. Coronavirus disease 2019 (COVID-19) was initially detected in Wuhan city, China. Chest CT features of COVID-19 pneumonia have been investigated mostly in China, and there is very little information available on the radiological findings occurring in other populations. In this study, we aimed to describe the characteristics of chest CT findings in confirmed cases of COVID-19 pneumonia in an Iranian population, based on a time classification.Methods. Eighty-nine patients with COVID-19 pneumonia, confirmed by a real-time RT-PCR test, who were admitted to non-ICU wards and underwent a chest CT scan were retrospectively enrolled. Descriptive evaluation of radiologic findings was performed using a classification based on the time interval between the initiation of the symptoms and chest CT-scan.Results. The median age of patients was 58.0 years, and the median time interval from the onset of symptoms to CT scan evaluation was 7 days. Most patients had bilateral (94.4%) and multifocal (91.0%) lung involvement with peripheral distribution (60.7%). Also, most patients showed involvement of all five lobes (77.5%). Ground-glass opacities (GGO) (84.3%) and mixed GGO with consolidation (80.9%) were the most common identified patterns. We also found that as the time interval between symptoms and CT scan evaluation increased, the predominant pattern changed from GGO to mixed pattern and then to elongated-containing and band-like-opacities-containing pattern; on the other hand, the percentage of lung involvement increased.Conclusions. Bilateral multifocal GGO, and mixed GGO with consolidation were the most common patterns of COVID-19 pneumonia in our study. However, these patterns might change according to the time interval from symptoms.

A Novel Method for Quantifying Total Thoracic Tumor Burden in Mice

Mouse models are powerful tools to study lung cancer initiation and progression in vivo and have contributed significantly to recent advances in therapy. Using micro-computed tomography to monitor and study parenchymal and extra-parenchymal metastases in existing murine models of lung cancer is challenging owing to a lack of radiographic contrast and difficulty in achieving respiratory gating. To facilitate the analysis of these in vivo imaging studies and study of tumor progression in murine models we developed a novel, rapid, semi-automated method of calculating thoracic tumor burden from computed tomography images. This method, in which commercially available software is used to calculate the mass of the thoracic cavity (MTC), takes into account the aggregate tumor burden in the thoracic cavity. The present study showed that in tumor-free mice, the MTC does not change over time and is not affected by breathing, whereas in tumor-bearing mice, the increase in the MTC is a measure of tumor mass that correlates well with tumor burden measured by lung weight. Tumor burden calculated with our MTC method correlated with that measured by lung weight as well as or better than that calculated using four established methods. To test this method, we assessed metastatic tumor development and response to a pharmacologic PLK1 inhibitor in an orthotopic xenograft mouse model. PLK1 inhibition significantly inhibited tumor growth. Our results demonstrate that the MTC method can be used to study dynamic changes in tumor growth and response to therapeutics in genetically engineered mouse models and orthotopic xenograft mouse models of lung cancer.

Imaging Protocols for Active Surveillance in Renal Cell Carcinoma

PURPOSE OF REVIEW

To review the growth kinetics of small renal masses and available imaging modalities for mass characterization and surveillance, highlight current organizational recommendations for the active surveillance of small renal masses, and discuss the most recently reported oncological outcomes of patients as they relate to various surveillance imaging protocols and progression to delayed intervention.

RECENT FINDINGS

Overall, organizational guideline recommendations are broad and lack specifics regarding timing and modality for follow-up imaging of small renal masses. Additionally, despite general consensus in the literature about certain criteria to trigger delayed intervention, there exist no formal guidelines. Active surveillance of small renal masses is an acceptable management strategy for patients with prohibitive surgical risk; however, standardized imaging protocols for surveillance are lacking, as are randomized, prospective trials to evaluate the ideal follow-up protocol.

Locoregional control and survival after lymph node SBRT in oligometastatic disease

Stereotactic body radiotherapy (SBRT) has emerged as an effective option in oligo-metastatic cancer patients affected by lymph node metastases, but its use might be questioned due to risk of regional and distant dissemination through the lymph node chain. The primary aim of our study was to assess the loco-regional control following SBRT in this setting. Ninety-one patients undergoing SBRT for at least one lymph node metastasis from miscellaneous primary tumors were retrospectively evaluated for patterns of failure and toxicity. locoregional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) at 4 years were 79 and 44%. Repeated use of local therapy after progression resulted in a median interval of 17 months until allocation to systemic therapy or supportive care. Forty-three percent of patients were alive at 4 years. Local failure, occurring in 15% of patients, was the only predictor of poor survival (HR: 3.06). Tumor diameter ≥ 30 mm and urothelial primary tumor predicted for impaired local control (HR: 4.59 and 5.43, respectively). Metastases from pulmonary cancer showed a significant earlier distant dissemination (HR: 3.53). Only acute and late grade 1–2 toxicities were reported except for 1 case of G3 dysphagia. Loco-regional failure risk is low (18%) and justifies the use of local therapies for patients with oligometastatic disease. Durable disease remission can be achieved by iterative use of local approaches. Local control is correlated to improved OS. Diameter and primary tumor type may affect response to SBRT and risk for early metastatic dissemination.

Intravoxel incoherent motion MRI for monitoring the therapeutic response of hepatocellular carcinoma to sorafenib treatment in mouse xenograft tumor models

Background With the introduction of targeted therapies, there has been a growing need for non-invasive imaging methods which accurately evaluate therapeutic effects and overcome the limitations of tumor size-based therapeutic response assessments. Purpose To assess diagnostic values of intra-voxel incoherent motion (IVIM) imaging in evaluating therapeutic effects of sorafenib on hepatocellular carcinoma (HCC) using mouse xenograft model. Material and Methods Twenty-four mice bearing Huh-7 were divided into a control group and two treatment groups received sorafenib doses of 5 mg/kg (5 mg-Tx) or 30 mg/kg (30 mg-Tx). IVIM imaging was performed using 10 b-values (0-900 s/mm²). The apparent diffusion coefficient (ADC), diffusion coefficient ( D), and perfusion fraction ( f) were measured for whole tumors and tumor periphery. Changes between baseline and post-treatment parameters ( Δ ADC, Δ D, and Δ f) were calculated, and these parameters were compared with microvessel density (MVD) and area of tumor cell death. Results The post-treatment f and Δ f for tumor periphery were significantly higher in control group, followed by 5 mg-Tx and 30 mg-Tx ( P < 0.001). MVD showed significant positive correlation with post-treatment f ( r = 0.584, P = 0.003) and negative correlation with D ( r = -0.495, P = 0.014) for tumor periphery, while no parameter showed significant correlation with area of tumor cell death. Conclusion The f is significantly correlated with MVD of HCC, and could potentially be used to evaluate the anti-angiogenic effects of sorafenib.

Biocompatible astaxanthin as novel contrast agent for biomedical imaging

Photoacoustic imaging (PAI) is a hybrid imaging modality with high resolution and sensitivity that can be beneficial for cancer staging. Due to insufficient endogenous photoacoustic (PA) contrast, the development of exogenous agents is critical in targeting cancerous tumors. The current study demonstrates the feasibility of marine-oriented material, astaxanthin, as a biocompatible PA contrast agent. Both silicon tubing phantoms and ex vivo bladder tissues are tested at various concentrations (up to 5 mg/ml) of astaxanthin to quantitatively explore variations in PA responses. A Q-switched Nd : YAG laser (λ = 532 nm) in conjunction with a 5 MHz ultrasound transducer is employed to generate and acquire PA signals from the samples. The phantom results presented that the PA signal amplitudes increase linearly with the astaxanthin concentrations (threshold detection = 0.31 mg/ml). The tissue injected with astaxanthin yields up to 16-fold higher PA signals, compared with that with saline. Due to distribution of the injected astaxanthin, PAI can image the margin of astaxanthin boles as well as quantify their volume in 3D reconstruction. Further investigations on selective tumor targeting are required to validate astaxanthin as a potential biocompatible contrast agent for PAI-assisted bladder cancer detection.

Rebound growth of hepatic colorectal metastases after neo-adjuvant chemotherapy: effect on survival after resection

BACKGROUND

A period of recovery is commonly allowed between completion of chemotherapy for colorectal liver metastases (CRLM) and resection, during which tumour progression may occur. The study-aim is to assess the growth of CRLM in this interval and association with outcome.

METHOD

Data on 146 patients were analysed. Change in tumour size was assessed by comparing size determined by imaging performed on completion of chemotherapy with that determined by examination of the resected specimen, categorised by RECIST criteria.

RESULTS

In the interval before surgery sixteen patients (11%) fulfilled criteria for partial response (PR), 48 (33%) had stable disease (SD) and 82 (56%) had progressive disease (PD). Among patients with PD following chemotherapy the median disease-free survival of patients who initially responded (26 months) was longer than in those who initially had stable disease (7 months) (P = 0.002). No association was noted between rate of tumour growth after completion of chemotherapy and disease-free survival.

CONCLUSION

Change in tumour size after completion of chemotherapy is variable and can be rapid, especially in patients who initially respond to treatment. However, disease-free survival is determined by tumour behaviour during treatment and not by change in size after completion of chemotherapy.

Temperature feedback-controlled photothermal treatment with diffusing applicator: theoretical and experimental evaluations

To minimize thermal injury, the current study evaluated the real-time temperature monitoring with a proportional-integrative-derivative (PID) controller during 980-nm photothermal treatment with a radially-diffusing applicator. Both simulations and experiments demonstrated comparable thermal behaviors in temperature distribution and the degree of irreversible tissue denaturation. The PID-controlled application constantly maintained the pre-determined temperature of 353 K (steady-state error = < 1 K). Due to constant energy delivery, coagulation volumes linearly increased up to 1.04 ± 0.02 cm(3) with irradiation time. Integration of temperature feedback with diffuser-assisted photothermal treatments can provide a feasible therapeutic modality to treat pancreatic tumors in an effective manner.

The pre-operative rate of growth of colorectal metastases in patients selected for liver resection does not influence post-operative disease-free survival

AIMS

To assess the potential association between the change in diameter of colorectal liver metastases between pre-operative imaging and liver resection and disease-free survival in patients who do not receive pre-operative liver-directed chemotherapy.

MATERIALS AND METHODS

Analysis of a prospectively maintained database of patients undergoing liver resection for colorectal liver metastases between 2005 and 2012 was undertaken. Change in tumour size was assessed by comparing the maximum tumour diameter at radiological diagnosis determined by imaging and the maximum tumour diameter measured at examination of the resected specimen in 157 patients.

RESULTS

The median interval from first scan to surgery was 99 days and the median increase in tumour diameter in this interval was 38%, equivalent to a tumour doubling time (DT) of 47 days. Tumour DT prior to liver resection was longer in patients with T1 primary tumours (119 days) than T2-4 tumours (44 days) and shorter in patients undergoing repeat surgery for intra-hepatic recurrence (33 days) than before primary resection (49 days). The median disease-free survival of the whole cohort was 1.57 years (0.2-7.3) and multivariate analysis revealed no association between tumour DT prior to surgery and disease-free survival.

CONCLUSIONS

The rate of growth of colorectal liver metastases prior to surgery should not be used as a prognostic factor when considering the role of resection.

Clinical utility of quantitative imaging

Quantitative imaging (QI) is increasingly applied in modern radiology practice, assisting in the clinical assessment of many patients and providing a source of biomarkers for a spectrum of diseases. QI is commonly used to inform patient diagnosis or prognosis, determine the choice of therapy, or monitor therapy response. Because most radiologists will likely implement some QI tools to meet the patient care needs of their referring clinicians, it is important for all radiologists to become familiar with the strengths and limitations of QI. The Association of University Radiologists Radiology Research Alliance Quantitative Imaging Task Force has explored the clinical application of QI and summarizes its work in this review. We provide an overview of the clinical use of QI by discussing QI tools that are currently used in clinical practice, clinical applications of these tools, approaches to reporting of QI, and challenges to implementing QI. It is hoped that these insights will help radiologists recognize the tangible benefits of QI to their patients, their referring clinicians, and their own radiology practice.

Elastic free energy drives the shape of prevascular solid tumors

It is well established that the mechanical environment influences cell functions in health and disease. Here, we address how the mechanical environment influences tumor growth, in particular, the shape of solid tumors. In an in vitro tumor model, which isolates mechanical interactions between cancer tumor cells and a hydrogel, we find that tumors grow as ellipsoids, resembling the same, oft-reported observation of in vivo tumors. Specifically, an oblate ellipsoidal tumor shape robustly occurs when the tumors grow in hydrogels that are stiffer than the tumors, but when they grow in more compliant hydrogels they remain closer to spherical in shape. Using large scale, nonlinear elasticity computations we show that the oblate ellipsoidal shape minimizes the elastic free energy of the tumor-hydrogel system. Having eliminated a number of other candidate explanations, we hypothesize that minimization of the elastic free energy is the reason for predominance of the experimentally observed ellipsoidal shape. This result may hold significance for explaining the shape progression of early solid tumors in vivo and is an important step in understanding the processes underlying solid tumor growth.

Semiautomatic volumetric tumor segmentation for hepatocellular carcinoma: comparison between C-arm cone beam computed tomography and MRI

RATIONALE AND OBJECTIVES

To evaluate the precision and reproducibility of a semiautomatic tumor segmentation software in measuring tumor volume of hepatocellular carcinoma (HCC) before the first transarterial chemo-embolization (TACE) on contrast-enhancement magnetic resonance imaging (CE-MRI) and intraprocedural dual-phase C-arm cone beam computed tomography (DP-CBCT) images.

MATERIALS AND METHODS

Nineteen HCCs were targeted in 19 patients (one per patient) who underwent baseline diagnostic CE-MRI and an intraprocedural DP-CBCT. The images were obtained from CE-MRI (arterial phase of an intravenous contrast medium injection) and DP-CBCT (delayed phase of an intra-arterial contrast medium injection) before the actual embolization. Three readers measured tumor volumes using a semiautomatic three-dimensional volumetric segmentation software that used a region-growing method employing non-Euclidean radial basis functions. Segmentation time and spatial position were recorded. The tumor volume measurements between image sets were compared using linear regression and Student's t-test, and evaluated with intraclass-correlation analysis (ICC). The inter-rater Dice similarity coefficient (DSC) assessed the segmentation spatial localization.

RESULTS

All 19 HCCs were analyzed. On CE-MRI and DP-CBCT examinations, respectively, 1) the mean segmented tumor volumes were 87 ± 8 cm(3) (2-873) and 92 ± 10 cm(3) (1-954), with no statistical difference of segmented volumes by readers of each tumor between the two imaging modalities and the mean time required for segmentation was 66 ± 45 seconds (21-173) and 85 ± 34 seconds (17-214) (P = .19); 2) the ICCs were 0.99 and 0.974, showing a strong correlation among readers; and 3) the inter-rater DSCs showed a good to excellent inter-user agreement on the spatial localization of the tumor segmentation (0.70 ± 0.07 and 0.74 ± 0.05, P = .07).

CONCLUSION

This study shows a strong correlation, a high precision, and excellent reproducibility of semiautomatic tumor segmentation software in measuring tumor volume on CE-MRI and DP-CBCT images. The use of the segmentation software on DP-CBCT and CE-MRI can be a valuable and highly accurate tool to measure the volume of hepatic tumors.

Comparison of semi-automatic volumetric VX2 hepatic tumor segmentation from cone beam CT and multi-detector CT with histology in rabbit models

RATIONALE AND OBJECTIVES

The purpose of this study was to compare tumor volume in a VX2 rabbit model as calculated using semiautomatic tumor segmentation from C-arm cone-beam computed tomography (CBCT) and multidetector computed tomography (MDCT) to the actual tumor volume.

MATERIALS AND METHODS

Twenty VX2 tumors in 20 adult male New Zealand rabbits (one tumor per rabbit) were imaged with CBCT (using an intra-arterial contrast medium injection) and MDCT (using an intravenous contrast injection). All tumor volumes were measured using semiautomatic three-dimensional volumetric segmentation software. The software uses a region-growing method using non-Euclidean radial basis functions. After imaging, the tumors were excised for pathologic volume measurement. The imaging-based tumor volume measurements were compared to the pathologic volumes using linear regression, with Pearson's test, and correlated using Bland-Altman analysis.

RESULTS

Average tumor volumes were 3.5 ± 1.6 cm(3) (range, 1.4-7.2 cm(3)) on pathology, 3.8 ± 1.6 cm(3) (range, 1.3-7.3 cm(3)) on CBCT, and 3.9 ± 1.6 (range, 1.8-7.5 cm(3)) on MDCT (P < .001). A strong correlation between volumes on pathology and CBCT and also with MDCT was observed (Pearson's correlation coefficient = 0.993 and 0.996, P < .001, for CBCT and MDCT, respectively). Bland-Altman analysis showed that MDCT tended to overestimate tumor volume, and there was stronger agreement for tumor volume between CBCT and pathology than with MDCT, possibly because of the intra-arterial contrast injection.

CONCLUSIONS

Tumor volume as measured using semiautomatic tumor segmentation software showed a strong correlation with the "real volume" measured on pathology. The segmentation software on CBCT and MDCT can be a useful tool for volumetric hepatic tumor assessment.

Size determination and response assessment of liver metastases with computed tomography--comparison of RECIST and volumetric algorithms

OBJECTIVE

To compare different three-dimensional volumetric algorithms (3D-algorithms) and RECIST for size measurement and response assessment in liver metastases from colorectal and pancreatic cancer.

METHODS

The volumes of a total of 102 liver metastases in 45 patients (pancreatic cancer, n=22; colon cancer, n=23) were estimated using three volumetric methods (seeded region growing method, slice-based segmentation, threshold-based segmentation) and the RECIST 1.1 method with volume calculation based on the largest axial diameter. Each measurement was performed three times by one observer. All four methods were applied to follow-up on 55 liver metastases in 29 patients undergoing systemic treatment (median follow-up, 3.5 months; range, 1-10 months). Analysis of variance (ANOVA) with post hoc tests was performed to analyze intraobserver variability and intermethod differences.

RESULTS

ANOVA showed significant higher volumes calculated according to the RECIST guideline compared to the other measurement methods (p<0.001) with relative differences ranging from 0.4% to 41.1%. Intraobserver variability was significantly higher (p<0.001) for RECIST and threshold based segmentation (3.6-32.8%) compared with slice segmentation (0.4-13.7%) and seeded region growing method (0.6-10.8%). In the follow-up study, the 3D-algorithms and the assessment following RECIST 1.1 showed a discordant classification of treatment response in 10-21% of the patients.

CONCLUSIONS

This study supports the use of volumetric measurement methods due to significant higher intraobserver reproducibility compared to RECIST. Substantial discrepancies in tumor response classification between RECIST and volumetric methods depending on applied thresholds confirm the requirement of a consensus concerning volumetric criteria for response assessment.

Evaluation of molecular targeted cancer drug by changes in tumor marker doubling times

BACKGROUND

We evaluated the usefulness of tumor marker doubling time (DT) as an efficacy indicator of a molecular targeted anticancer agent.

METHODS

Twenty-five patients with advanced hepatocellular carcinoma (HCC) received TSU-68, a multiple tyrosine kinase inhibitor. Exponential increase in HCC-specific tumor marker levels (alpha-fetoprotein or des-gamma-carboxyprothrombin) was seen in 15 of them prior to TSU-68 administration. The relationship between tumor marker DT and tumor volume DT was evaluated. Next, tumor marker DT in the first 8 weeks of TSU-68 administration was compared with tumor marker DT before treatment. Efficacy evaluation based on changes in tumor marker DT was compared with Response Evaluation Criteria In Solid Tumors (RECIST).

RESULTS

Tumor marker DT and tumor volume DT were almost identical (r(2) = 0.94, P < 0.001) in each patient before TSU-68 administration. Efficacy evaluation based on changes in tumor marker DT on TSU-68 administration was in accordance with RECIST in 12/15 cases. Discordance was observed in three cases, for which RECIST indicated disease progression in spite of elongated tumor marker DT. Those cases showed substantial tumor necrosis without volume shrinkage or appearance of new lesions in spite of apparent effects on target lesions.

CONCLUSIONS

Serum tumor marker DT can be used to evaluate viable tumor burden irrespective of the presence of tumor necrosis which can compromise radiographic evaluation. This approach may be applicable to the evaluation of responses to chemotherapy, particularly to cytostatic agents (ClinicalTrials.gov number, NCT00784290).

Preclinical assessment of a 980-nm diode laser ablation system in a large animal tumor model

PURPOSE

To characterize the performance of a 980-nm diode laser ablation system in an in vivo tumor model.

MATERIALS AND METHODS

This study was approved by the institutional animal care and use committee. The ablation system consisted of a 15-W, 980-nm diode laser, flexible diffusing-tipped fiber optic, and 17-gauge internally cooled catheter. Ten immunosuppressed dogs were inoculated subcutaneously with canine-transmissible venereal tumor fragments in eight dorsal locations. Laser ablations were performed at 79 sites where inoculations were successful (99%) at powers of 10 W, 12.5 W, and 15 W, with exposure times between 60 and 180 seconds. In 20 cases, multiple overlapping ablations were performed. After the dogs were euthanized, the tumors were harvested, sectioned along the applicator tract, measured, and photographed. Measurements of ablation zone were performed on gross specimen. Histopathology and viability staining was performed with hematoxylin and eosin and nicotinamide adenine dinucleotide hydrogen staining.

RESULTS

Gross pathologic examination confirmed a well circumscribed ablation zone with sharp boundaries between thermally ablated tumor in the center surrounded by viable tumor tissue. When a single applicator was used, the greatest ablation diameters ranged from 12 mm at the lowest dose (10 W, 60 seconds) to 26 mm at the highest dose (15 W, 180 seconds). Multiple applicators created ablation zones as large as 42 mm in greatest diameter (with the lasers operating at 15 W for 120 seconds).

CONCLUSIONS

The new 980-nm diode laser and internally cooled applicator effectively create large ellipsoid thermal ablations in less than 3 minutes.

Does multidetector CT attenuation change in colon cancer liver metastases treated with 90Y help predict metabolic activity at FDG PET?

PURPOSE

To evaluate the correlation between change in attenuation and tumor metabolic activity assessed by using fluorodeoxyglucose (FDG) positron emission tomography (PET) in colon cancer liver metastases treated with yttrium 90 ((90)Y) radioembolization.

MATERIALS AND METHODS

This Health Insurance Portability and Accountability Act-compliant retrospective study was approved by the institutional review board; patient informed consent was waived. Unresectable chemorefractory colon cancer liver metastases treated with (90)Y radioembolization in 28 patients were evaluated at pre- and posttreatment multidetector computed tomographic (CT) and FDG PET scans. Maximum cross-sectional diameter, volume, and overall attenuation of target lesions were calculated. The percentage change (%Delta) in these parameters after treatment was calculated and correlated with the standardized uptake value (SUV) analysis at FDG PET. The accuracy of the radiologic parameters in helping predict response to treatment at FDG PET was assessed. Data were analyzed by using the Student t, Wilcoxon matched pair, Mann-Whitney, Spearman rank correlation, and chi(2) tests. The significance level was set at .05.

RESULTS

Seventy-four metastatic lesions in 10 women and 18 men (mean age, 61.5 years +/- 14.3 [standard deviation]) were evaluated. Mean follow-up interval for multidetector CT after treatment was 30 days. A significant reduction in maximum cross-sectional diameter, volume, and attenuation was observed from pre- to posttreatment multidetector CT (P < .05). The %Delta in attenuation had higher correlation with %Delta in SUV (r = 0.61) than diameter (r = 0.39) or volume (r = 0.49) and also predicted the metabolic activity at FDG PET with higher sensitivity (P < .001). By using a threshold level of a reduction in attenuation of 15% or greater, attenuation showed 84.2% sensitivity and 83.3% specificity in predicting response at FDG PET evaluation.

CONCLUSION

Changes in attenuation of colon cancer liver metastases treated with (90)Y radioembolization correlate highly with metabolic activity at FDG PET and may be useful as an early surrogate marker for assessing treatment response.

Agreement between competing imaging measures of response of hepatocellular carcinoma to yttrium-90 radioembolization

PURPOSE

There are currently at least six major competing criteria used to determine response to yttrium-90 and other liver-directed therapies, including: (i) Response Evaluation Criteria in Solid Tumors (RECIST); (ii) World Health Organization (WHO), (iii) volumetric, (iv) two-dimensional (2D) European Association for the Study of the Liver (EASL), and (v) three-dimensional (3D) EASL criteria; and (vi) functional diffusion-weighted (DW) magnetic resonance (MR) imaging. This study evaluated agreement among these competing tumor response classification schemes based on quantitative measurements of tumor size, necrosis, and changes in water mobility.

MATERIALS AND METHODS

In this retrospective study, 20 patients with hepatocellular carcinoma (HCC) underwent (90)Y radioembolization. The patients' tumor burden before and 3-6 months after treatment was assessed with MR imaging. The percent change in size of tumors was used to classify patients into response categories. kappa and agreement statistics were used to compare concordance among the different criteria.

RESULTS

Conventional size criteria (RECIST, WHO, and volumetric) all had a substantial level of agreement (kappa = 0.76-0.78) when classifying patients into response categories. However, the conventional size criteria in relation to 2D or 3D EASL had only slight to moderate concurrence, with kappa statistics as low as 0.06. Two-dimensional EASL criteria and functional DW MR imaging resulted in the highest response rates, 55% (n = 11) and 75% (n = 15), respectively, whereas conventional size criteria produced lower response rates.

CONCLUSIONS

Classification of HCC response to (90)Y radioembolization is related to which of the competing criteria are used. It is recommended that anatomic imaging criteria be used as the primary method to determine response and functional imaging criteria be used as a complementary secondary method.

Liver tumour segmentation using contrast-enhanced multi-detector CT data: performance benchmarking of three semiautomated methods

OBJECTIVE

Automatic tumour segmentation and volumetry is useful in cancer staging and treatment outcome assessment. This paper presents a performance benchmarking study on liver tumour segmentation for three semiautomatic algorithms: 2D region growing with knowledge-based constraints (A1), 2D voxel classification with propagational learning (A2) and Bayesian rule-based 3D region growing (A3).

METHODS

CT data from 30 patients were studied, and 47 liver tumours were isolated and manually segmented by experts to obtain the reference standard. Four datasets with ten tumours were used for algorithm training and the remaining 37 tumours for testing. Three evaluation metrics, relative absolute volume difference (RAVD), volumetric overlap error (VOE) and average symmetric surface distance (ASSD), were computed based on computerised and reference segmentations.

RESULTS

A1, A2 and A3 obtained mean/median RAVD scores of 17.93/10.53%, 17.92/9.61% and 34.74/28.75%, mean/median VOEs of 30.47/26.79%, 25.70/22.64% and 39.95/38.54%, and mean/median ASSDs of 2.05/1.41 mm, 1.57/1.15 mm and 4.12/3.41 mm, respectively. For each metric, we obtained significantly lower values of A1 and A2 than A3 (P < 0.01), suggesting that A1 and A2 outperformed A3.

CONCLUSIONS

Compared with the reference standard, the overall performance of A1 and A2 is promising. Further development and validation is necessary before reliable tumour segmentation and volumetry can be widely used clinically.

Predicting outcome by growth rate of locally recurrent retroperitoneal liposarcoma: the one centimeter per month rule

OBJECTIVE

To identify the prognostic variables that predict disease-specific survival and second local recurrence-free survival in patients with recurrent retroperitoneal liposarcoma so as to guide clinical management.

SUMMARY BACKGROUND DATA

Local recurrence after complete resection of primary retroperitoneal liposarcoma is a common clinical problem that frequently leads to morbidity and mortality. Factors that determine survival in patients with a local recurrence after complete resection of the primary and rerecurrence after resection of the first local recurrence have not been clearly defined.

METHODS

From a prospective sarcoma database we selected 105 patients who had at least one local recurrence following complete resection of a primary retroperitoneal liposarcoma between July 1982 and December 2005. Of these patients, 61 underwent complete resection of their first local recurrence. Study endpoints included second local recurrence-free survival for these 61 patients and disease-specific survival for all 105 patients. Univariate analysis was performed with the Kaplan-Meier method and log-rank test, and multivariate analysis with the Cox proportional hazards model and score test. Local recurrence growth rate was defined as the radiographic size of the local recurrence divided by the time to local recurrence from the primary resection.

RESULTS

Median follow-up was 65 months. Local recurrence size, primary histologic variant and grade, and local recurrence growth rate were independent predictors of disease-specific survival. For those undergoing reresection, local recurrence size and local recurrence growth rate independently influenced development of a second local recurrence. Only patients with local recurrence growth rates of less than 0.9 cm/mo were associated with improved survival after aggressive resection of the local recurrence.

CONCLUSIONS

Local recurrence growth rate is strongly associated with disease-specific survival and local control for patients with completely resected locally recurrent retroperitoneal liposarcoma. Despite aggressive operative management patients with a local recurrence growth rate greater than 0.9 cm/mo were associated with poor outcomes and should be considered for enrollment in clinical trials employing novel agents.

Semiquantitative visual approach to scoring lung cancer treatment response using computed tomography: a pilot study

OBJECTIVE

Our objective was to compare a newly developed semiquantitative visual scoring (SVS) method with the current standard, the Response Evaluation Criteria in Solid Tumors (RECIST) method, in the categorization of treatment response and reader agreement for patients with metastatic lung cancer followed by computed tomography.

MATERIALS AND METHODS

The 18 subjects (5 women and 13 men; mean age, 62.8 years) were from an institutional review board-approved phase 2 study that evaluated a second-line chemotherapy regimen for metastatic (stages III and IV) non-small cell lung cancer. Four radiologists, blinded to the patient outcome and each other's reads, evaluated the change in the patients' tumor burden from the baseline to the first restaging computed tomographic scan using either the RECIST or the SVS method. We compared the numbers of patients placed into the partial response, the stable disease (SD), and the progressive disease (PD) categories (Fisher exact test) and observer agreement (kappa statistic).

RESULTS

Requiring the concordance of 3 of the 4 readers resulted in the RECIST placing 17 (100%) of 17 patients in the SD category compared with the SVS placing 9 (60%) of 15 patients in the partial response, 5 (33%) of the 15 patients in the SD, and 1 (6.7%) of the 15 patients in the PD categories (P < 0.0001). Interobserver agreement was higher among the readers using the SVS method (kappa, 0.54; P < 0.0001) compared with that of the readers using the RECIST method (kappa, -0.01; P = 0.5378).

CONCLUSIONS

Using the SVS method, the readers more finely discriminated between the patient response categories with superior agreement compared with the RECIST method, which could potentially result in large differences in early treatment decisions for advanced lung cancer.

Exact CT-based liver volume calculation including nonmetabolic liver tissue in three-dimensional liver reconstruction

Exact preoperative determination of the liver volume is of great importance prior to hepatobiliary surgery, especially in living donated liver transplantation (LDLT) and extended hepatic resections. Modern surgery-planning systems estimate these volumes from segmented image data. In an experimental porcine study, our aim was (1) to analyze and compare three volume measurement algorithms to predict total liver volume, and (2) to determine vessel tree volumes equivalent to nonmetabolic liver tissue. Twelve porcine livers were examined using a standardized three-phase computed tomography (CT) scan and liver volume was calculated computer-assisted with the three different algorithms. After hepatectomy, livers were weighed and their vascular system plasticized followed by CT scan, CT reconstruction and re-evaluation of total liver and vessel volumes with the three different algorithms. Blood volume determined by the plasticized model was at least 1.89 times higher than calculated by multislice CT scans (9.7% versus 21.36%, P=0.028). Analysis of 3D-CT-volumetry showed good correlation between the actual and the calculated liver volume in all tested algorithms with a high significant difference in estimating the liver volume between Heymsfield versus Heidelberg (P=0.0005) and literature versus Heidelberg (P=0.0060). The Heidelberg algorithm reduced the measuring error with deviations of only 1.2%. The present results suggest a safe and highly predictable use of 3D-volumetry in liver surgery for evaluating liver volumes. With a precise algorithm, the volume of remaining liver or single segments can be evaluated exactly and potential operative risks can therefore be better calculated. To our knowledge, this study implies for the first time a blood pool, which corresponds to nonmetabolic liver tissue, of more than 20% of the whole liver volume.

Discrete-space versus continuous-space lesion boundary and area definitions

Measurement of the size of anatomic regions of interest in medical images is used to diagnose disease, track growth, and evaluate response to therapy. The discrete nature of medical images allows for both continuous and discrete definitions of region boundary. These definitions may, in turn, support several methods of area calculation that give substantially different quantitative values. This study investigated several boundary definitions (e.g., continuous polygon, internal discrete, and external discrete) and area calculation methods (pixel counting and Green's theorem). These methods were applied to three separate databases: A synthetic image database, the Lung Image Database Consortium database of lung nodules and a database of adrenal gland outlines. Average percent differences in area on the order of 20% were found among the different methods applied to the clinical databases. These results support the idea that inconsistent application of region boundary definition and area calculation may substantially impact measurement accuracy.

Imaging techniques to evaluate the response to treatment in oncology: current standards and perspectives

Response evaluation in solid tumours currently uses radiological imaging techniques to measure changes under treatment. Imaging requires a well-defined anatomical lesion to be viewed and relies on the measurement of a reduction in tumour size during treatment as the basis for presumed clinical benefit. However, with the development of anti-angiogenesis agents, anatomical imaging has became inappropriate as certain tumours would not reduce in size. Functional studies are therefore necessary and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), DCE-computed tomography (CT) and DCE-ultrasonography (US) are currently being evaluated for monitoring treatments. Diffusion-weighted MR imaging (DW-MRI) and magnetic resonance spectroscopy (MRS) are also capable of detecting changes in cell density and metabolite content within tumours. In this article, we review anatomical and functional criteria currently used for monitoring therapy. We review the published data on DCE-MRI, DCE-CT, DCE-US, DW-MRI and MRS. This literature review covers the following area: basic principles of the technique, clinical studies, reproducibility and repeatability, limits and perspectives in monitoring therapy. Anatomical criteria such as response evaluation criteria in solid tumours (RECIST) will require adaptation to employ not only new tools but also different complementary techniques such as functional imaging in order to monitor therapeutic effects of conventional and new anti-cancer agents.

Qualitative radiology assessment of tumor response: does it measure up?

Our purpose was to assess whether a simpler qualitative evaluation of tumor response by computed tomography is as reproducible and predictive of clinical outcome as the Response Evaluation Criteria in Solid Tumors (RECIST) and World Health Organization (WHO) methods. This study was a two-reader retrospective evaluation in which qualitative assessment resulted in agreement in 21 of 23 patients with metastatic colorectal carcinoma (91.3%, kappa=0.78; 95% CI, 0.51-1.00). Hepatic metastases were classified as increased, decreased, or unchanged, compared with agreement in 20 of 23 patients (87.0%) for RECIST (kappa=0.62; 95% CI, 0.23-1.00) and WHO (kappa=0.67; 95% CI, 0.34-1.00) methods. Patients were placed into partial response, stable disease, and disease progression categories. Time to progression of disease was better predicted qualitatively than by RECIST or WHO. Our pilot data suggest that our qualitative scoring system is more reproducible and predictive of patient clinical outcome than the RECIST and WHO methods.

Radiologic measurements of tumor response to treatment: practical approaches and limitations

Objective response assessment is important to describe the treatment effect of anticancer drugs. Standardization by using a "common language" is also important for comparison of results from different trials. In contrast to clinical results, which can be subjective, diagnostic imaging provides a greater opportunity for objectivity and standardization. It was generally accepted that a decrease in tumor size correlated with treatment effect; as a result, imaging was adopted for lesion measurement in the World Health Organization (WHO) criteria in 1979. However, because of some limitations of the WHO criteria, the Response Evaluation Criteria in Solid Tumors (RECIST) were introduced in 2000. In RECIST, imaging was recognized as indispensable for response evaluation of solid tumors. Nevertheless, the widespread use of multidetector computed tomography and other imaging innovations have made RECIST outdated, with a concomitant need for modifications. Meanwhile, newer anticancer agents with targeted mechanisms of action have demonstrated an inherent limitation and unsuitability of anatomic tumor evaluation that assesses only lesion size. In addition, the effect of these new drugs changes the paradigm according to which tumor response or response rate is measured. Complete and partial responses cannot be the end points in all clinical trials; in some cases, disease control or progression-free survival may be the more relevant end point.

How to assess anti-tumour efficacy by imaging techniques

Response evaluation in the assessment of potential new anti-cancer therapies is undergoing intense investigation and change. Current imaging techniques most commonly used in early phase clinical trials are limited to providing reliable and reproducible anatomical data demonstrating a change in size and reduction in tumour volume thereby inferring patient benefit. Current imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) by their nature require computer programs and software. This is a constantly evolving field and upgraded technology enables faster acquisition times for scans, greater anatomical detail and accurate volumetric data to be acquired. Dynamic studies allow contrast agents to be visualised in any given structure over time, so blood flow, blood volume and permeability can be assessed thereby demonstrating function. The advent of many new anti-cancer agents with novel modes of action such as anti-angiogenesis agents act by preventing the development of a suitable blood supply to sustain tumour growth. Such agents do not actively destroy tumour cells so do not exhibit a 'cytocidal' effect as traditional anti-cancer agents do but prevent tumour growth, so can be regarded as 'cytostatic' agents. Therefore, traditional response evaluation criteria may not be appropriate to assess drug efficacy or 'activity' in achieving patient benefit. New techniques have also been developed so the 'function' or metabolism can be demonstrated and tumour serum markers and other factors also require consideration rather than relying on a single modality alone. This article reviews the current accepted response criteria and highlights some newer techniques which will almost certainly play a major role in the assessment of new anti-cancer therapy, particularly in the development of cytostatic agents which are playing an ever increasing role.

Nasopharyngeal Cancers: Which Method Should be Used to Measure these Irregularly Shaped Tumors on Cross-Sectional Imaging?

PURPOSE

To determine whether the standard techniques of measuring tumor size and change in size after treatment could be applied to the measurement of nasopharyngeal cancers, which are often irregular in shape.

METHODS AND MATERIALS

The standard measurements of bidimensional (BDM) (World Health Organization criteria) and unidimensional (UDM) (Response Evaluation Criteria in Solid Tumors [RECIST] criteria), together with the maximum depth of the tumor perpendicular to the pharyngeal wall (DM), were acquired from axial magnetic resonance images of primary nasopharyngeal carcinoma in 44 patients at diagnosis and in 29 of these patients after treatment. Tumor volume measurements (VM), acquired from the summation of areas from the axial magnetic resonance images, were used as the reference standard.

RESULTS

There was a significant association between VM and BDM with respect to tumor size at diagnosis (p = 0.002), absolute change in tumor size after treatment (p < 0.001), and percentage change in tumor size after treatment (p = 0.044), but not between VM and UDM. There was also a significant association between VM and DM with respect to percentage change in tumor size after treatment (p = <0.0001) but not absolute change (p = 0.222).

CONCLUSION

When using simple measurements to assess irregularly shaped nasopharyngeal cancers, the BDM should be used to measure size at diagnosis and the BDM and percentage change in size with treatment. Unidimensional measurement does not reflect size or change in size, and therefore the RECIST criteria may not be applicable to all tumor shapes. The use of DM requires further evaluation.

The effect of lung volume on nodule size on CT

RATIONALE AND OBJECTIVES

We sought to determine how measures of nodule diameter and volume on computed tomography (CT) vary with changes in inspiratory level.

MATERIALS AND METHODS

CT scans were performed with inspiration suspended at total lung capacity (TLC) and then at residual volume (RV) in 41 subjects, in whom 75 indeterminate lung nodules were detected. A fully automated contouring program was used to segment the lungs; followed by segmentation of all nodules and the corresponding lobe using semiautomated contouring in both TLC and RV scans. The percent changes in lung and lobar volumes between TLC and RV were correlated with percent changes in nodule diameters and volumes.

RESULTS

Both nodule diameter and volume varied nonuniformly from TLC to RV-some nodules decreased in size, while others increased. There was a 16.8% mean change in absolute volume across all nodules. Stratified by size, the mean value of the absolute percent volume changes for nodules > or =5 mm and <5 mm were not significantly different (P = .26). Stratified by maximum attenuation, the mean value of the absolute percent volume changes between the TLC and RV series for noncalcified (17.7%, SD = 13.1) and completely calcified nodules (8.6% SD = 5.7) were significantly different (P < .05).

CONCLUSION

Significant differences in nodule size were measured between TLC and RV scans. This has important implications for standardizing acquisition protocols in any setting where size and, more important, size change are being used for purposes of lung cancer staging, nodule characterization, or treatment response assessment.

Adrenal metastases: CT-guided and MR-thermometry-controlled laser-induced interstitial thermotherapy

The aim of the study was to evaluate the feasibility, safety and effectiveness of CT-guided and MR-thermometry-controlled laser-induced interstitial thermotherapy (LITT) in adrenal metastases. Nine patients (seven male, two female; average age 65.0 years; range 58.7-75.0 years) with nine unilateral adrenal metastases (mean diameter 4.3 cm) from primaries comprising colorectal carcinoma (n = 5), renal cell carcinoma (n = 1), oesophageal carcinoma (n = 1), carcinoid (n = 1), and hepatocellular carcinoma (n = 1) underwent CT-guided, MR-thermometry-controlled LITT using a 0.5 T MR unit. LITT was performed with an internally irrigated power laser application system with an Nd:YAG laser. A thermosensitive, fast low-angle shot 2D sequence was used for real-time monitoring. Follow-up studies were performed at 24 h and 3 months and, thereafter, at 6-month intervals (median 14 months). All patients tolerated the procedure well under local anaesthesia. No complications occurred. Average number of laser applicators per tumour: 1.9 (range 1-4); mean applied laser energy 33 kJ (range 15.3-94.6 kJ), mean diameter of the laser-induced coagulation necrosis 4.5 cm (range 2.5-7.5 cm). Complete ablation was achieved in seven lesions, verified by MR imaging; progression was detected in two lesions in the follow-up. The preliminary results suggest that CT-guided, MR-thermometry-controlled LITT is a safe, minimally invasive and promising procedure for treating adrenal metastases.

Measures of response: RECIST, WHO, and new alternatives

RECIST (Response Evaluation Criteria in Solid Tumors) is a widely employed method introduced in 2000 to assess change in tumor size in response to therapy. The simplicity of the technique, however, contrasts sharply with the increasing sophistication of imaging instrumentation. Anatomically based imaging measurement, although supportive of drug development and key to some accelerated drug approvals, is being pressed to improve its methodologic robustness, particularly in the light of more functionally-based imaging that is sensitive to tissue molecular response such as fluorodeoxyglucose positron emission tomography. Nevertheless ready availability of computed tomography and magnetic resonance imaging machines largely assures anatomically based imaging a continuing role in clinical trials for the foreseeable future. Recent advances in image processing enabled by the computational power of modern clinical scanners open a considerable opportunity to characterize tumor response to therapy as a complement to image acquisition. Various alternative quantitative volumetric approaches have been proposed but have yet to gain wide acceptance by clinical and regulatory communities, nor have these more complex techniques shown incontrovertible evidence of greater reproducibility or predictive value of clinical events and outcome. Unless plans are created for clinical trials that incorporate the design needed to prove the added value and unique clinical utility of these novel approaches, any theoretical benefit of these more elaborate methods could remain unfulfilled.

Volumetric analysis of liver metastases in computed tomography with the fuzzy C-means algorithm

Tumor size is often determined from computed tomography (CT) images to assess disease progression. A study was conducted to demonstrate the advantages of the fuzzy C-means (FCM) algorithm for volumetric analysis of colorectal liver metastases in comparison with manual contouring. Intra-and interobserver variability was assessed for manual contouring and the FCM algorithm in a study involving contrast-enhanced helical CT images of 43 hypoattenuating liver lesions from 15 patients with a history of colorectal cancer. Measurement accuracy and interscan variability of the FCM and manual methods were assessed in a phantom study using paraffin pseudotumors. In the clinical imaging study, intra-and interobserver variability was reduced using the FCM algorithm as compared with manual contouring (P = 0.0070 and P = 0.0019, respectively). Accuracy of the measurement of the pseudotumor volume was improved using the FCM method as compared with the manual method (P = 0.047). Interscan variability of the pseudotumor volumes was measured using the FCM method as compared with the manual method (P = 0.04). The FCM algorithm volume was highly correlated with the manual contouring volume (r = 0.9997). Finally, the shorter time spent in calculating tumor volume using the FCM method versus the manual contouring method was marginally statistically significant (P = 0.080). These results suggest that the FCM algorithm has substantial advantages over manual contouring for volumetric measurement of colorectal liver metastases from CT.

Whole-brain radiotherapy with or without efaproxiral for the treatment of brain metastases: Determinants of response and its prognostic value for subsequent survival

PURPOSE

To determine the prognostic factors for radiographic response and its prognostic value for subsequent survival in patients undergoing whole-brain radiotherapy (WBRT) for brain metastases.

METHODS AND MATERIALS

Five hundred fifteen eligible patients were randomized in a phase III trial evaluating WBRT and supplemental oxygen with or without efaproxiral, an allosteric modifier of hemoglobin that reduces hemoglobin oxygen-binding affinity and enhances tumor oxygenation, potentially increasing tumor radiosensitivity. Brain images were obtained at baseline and at scheduled follow-up visits after WBRT. Landmark analysis was used to assess the ability of response at selected time points to predict subsequent survival. Logistic regression was used to assess determinants of response at 3 months.

RESULTS

Treatment arm, Karnofsky Performance Status, presence or absence of liver metastases, and primary site were all determinants of response at the 3-month follow-up visit, with patients in the efaproxiral arm experiencing a 67% greater odds of response at this visit (p = 0.02). Response at 3 and 6 months was a significant prognostic factor for longer subsequent survival.

CONCLUSIONS

The 3-month scan is a valuable prognostic factor for subsequent survival in patients with brain metastases treated with WBRT. Patients in the efaproxiral arm had a higher response rate at 3 and 6 months than those in the control arm.

MR-Guided Laser Ablation

MR-guided LITT is a safe and effective treatment modality that improves survival in well-selected patients who have liver metastases. A major advantage of MR-guided LITT is that it can be easily performed under local anesthesia in an outpatient setting with a low complication rate.

Gastrointestinal stromal tumor: new nodule-within-a-mass pattern of recurrence after partial response to imatinib mesylate

PURPOSE

To investigate a new pattern of tumor recurrence observed at imaging in patients with metastatic gastrointestinal stromal tumor (GIST) after initial partial response to imatinib mesylate.

MATERIALS AND METHODS

Ninety-two patients with metastatic GIST who underwent treatment in a clinical trial with oral imatinib mesylate were followed up for 29 months. An institutional review board-approved protocol was used. The study complied with the Health Insurance Portability and Accountability Act, and written informed consent was obtained from all patients. Images of the chest, abdomen, and pelvis, acquired with computed tomography (CT), positron emission tomography (PET), and, in some cases, magnetic resonance imaging, were evaluated for treatment response and disease recurrence. Thirty-nine patients (29 men, 10 women; age range, 18-84 years; mean, 49.2 years) had recurrent disease after an initial variable period of response (range, 2-24 months; median, 14.4 months). Initial response was determined with findings of decreased uptake of fluorine 18 fluorodeoxyglucose at PET, shrinkage of tumor, and decreased attenuation at CT. Images were evaluated for disease recurrence by two experienced radiologists who were blinded to each other's interpretation but not to clinical details. Final reading was performed by consensus.

RESULTS

A nodule within a mass was seen in 21 of 39 patients (in intrahepatic tumor [n = 8], extrahepatic tumor [n = 10], or both intra- and extrahepatic tumors [n = 3]) and was the first sign of disease progression in 17 of 21 patients. Other patterns of recurrence included new site of disease (n = 7), regrowth of preexistent lesion (n = 20), and mixed (more than one) pattern (n = 9). Disease progression was verified at needle biopsy (n = 16), follow-up imaging (n = 14), and/or surgical resection (n = 9).

CONCLUSION

A nodule within a mass is an important sign of recurrent GIST, but measurements of overall tumor size may not enable detection of such nodules.

Comparison of treatment response classifications between unidimensional, bidimensional, and volumetric measurements of metastatic lung lesions on chest computed tomography

RATIONALE AND OBJECTIVES

To study the agreement in treatment response classifications between unidimensional (1D), bidimensional (2D), and volumetric (3D) methods of measuring metastatic lung nodules on chest computed tomography (CT).

MATERIALS AND METHODS

Chest CT scans of 15 patients undergoing treatment for metastatic colorectal, renal cell, or breast carcinoma to the lungs were analyzed. CT images were acquired with 3 mm collimation and contiguous reconstruction. Two or three lung lesions were selected for each patient. Lesions were analyzed at baseline and two follow-up intervals of 1-4 months. 1D and 2D measurements were made with electronic calipers, while nodule volume was measured using a semiautomated segmentation system. Following the World Health Organization and RECIST (Response Evaluation Criteria in Solid Tumors) criteria, patients were categorized into four treatment response classifications. Volumetric criteria were used to classify response based on 3D measurements.

RESULTS

Thirty-two lesions from 15 patients were analyzed. Because each patient had a baseline and two follow-up scans, this yielded 30 response classifications for each measurement technique. The 1D, 2D, and 3D measurements were concordant in 21 of 30 classifications. The 1D and 3D measurements were concordant in 29 of 30 classifications, while the 2D and 3D measurements were concordant in 23 of 30 classifications. Level of agreement among the three methods was measured using a kappa statistic (K). For 1D compared with 3D, K = 0.739 +/- 0.345 (visits 1, 2) and 0.273 +/- 0.323 (visits 2, 3). For 2D compared with 3D, K = 0.655 +/- 0.325 (visits 1, 2) and 0.200 +/- 0.208 (visits 2, 3). Agreement among the methods for round and ovoid nodules was also fair to poor.

CONCLUSION

The three methods of tumor measurement show fair to poor agreement in treatment response classification. These findings have negative implications for the accuracy in which patients are classified under the World Health Organization or RECIST criteria and managed under cancer treatment protocols.

Breast cancer metastases in liver: laser-induced interstitial thermotherapy--local tumor control rate and survival data

PURPOSE

To evaluate the local tumor control rate and survival data for magnetic resonance (MR) imaging-guided laser ablation of breast cancer liver metastases by using laser-induced interstitial thermotherapy (LITT).

MATERIALS AND METHODS

MR-guided LITT was performed in 232 female patients with 578 liver metastases from breast cancer. Survival rates were calculated with the Kaplan-Meier method. Indications for the procedure were defined for patients with no more than five metastases, none of which were larger than 5 cm in diameter, as follows: recurrent liver metastases after partial liver resection (8.2%), metastases in both liver lobes (45.2%), locally nonresectable tumors (19%), general contraindications for surgery (2.6%), or refusal to undergo surgical resection (25%).

RESULTS

Local recurrence rate at 6-month follow-up after LITT was 2.3% (five of 213) for metastases up to 2 cm in diameter, 4.3% (seven of 162) for metastases 2-3 cm in diameter, 3.2% (two of 63) for metastases 3-4 cm in diameter, and 1.9% (one of 52) for metastases larger than 4 cm in diameter. No additional local tumor progression was observed beyond 6 months. The mean survival rate for all treated patients, with calculation started on the date of diagnosis of the metastases treated with LITT, was 4.9 years (95% confidence interval: 4.3, 5.4). The median survival was 4.3 years; 1-year survival, 96%; 2-year survival, 80%; 3-year survival, 63%; and 5-year survival, 41%. The mean survival after the first LITT treatment was 4.2 years (95% confidence interval: 3.6, 4.8).

CONCLUSION

MR-guided LITT yields high local tumor control and survival rates in patients with liver metastases from breast cancer.

A statistical simulation study finds discordance between WHO criteria and RECIST guideline

OBJECTIVE

Tumor shrinkage has been adopted as an end point for evaluating the effectiveness of new anticancer agents. The WHO (World Health Organization) criterion suggested measuring the tumor shrinkage by the change in the product of maximal diameter (MD) and the corresponding largest perpendicular diameter (LPD). The RECIST (Response Evaluation Criteria In Solid Tumor) guideline proposed using the change in MD only, based on the observation that this measure is more linearly related to tumor cell kill than the cross product (MD*LPD). Both criteria classify patients into four categories of response: complete response (CR: total disappearance), partial response (PR), stable disease (SD), and progressive disease (PD) but the criteria used in the definition of PD vary. It was anticipated that patients' actual response categorization would not be considerably affected by utilizing the RECIST criteria instead of WHO. Empirical evidence supporting this fact was provided by retrospective analysis of several large datasets.

STUDY DESIGN AND SETTING

A statistical simulation is performed to generate tumor measurements and patient response data under meaningful probability distributions with parameters based on data from 130 patients on clinical trials at a cancer center. Concordance measures between the two response criteria (Kappa coefficient and percentage disagreement per response category) are assessed systematically over various combinations of the percentage of elliptical tumors at baseline and the percentage of tumors changing shape from baseline to follow-up.

RESULTS

The overall percentage of disagreement between the two methods of response assessment is found to be in the range of 14-20%. The patients categorized by WHO in the PR, SD, and PD groups fall into a different category when assessed by RECIST between 8-16%, 3-12%, and 32-35% of the times, respectively. The kappa coefficient ranges between 0.68-0.77. The proportion of elliptical tumors at baseline does not greatly impact the concordance, but the magnitude of the change in the aspect ratio has a large impact.

CONCLUSION

Response assessment as measured by RECIST, with both a change in the underlying metric and change in definition of progression, often results in different categorization of response compared to WHO. The difference in response categorization may be problematic when new experimental therapies are compared to conventional agents whose response rates have been established in historical trials. The apparent lower rate of disease progression with RECIST may mean that more patients remain on therapy. Higher percentages of patients with SD need to be interpreted cautiously by distinguishing those due to the change in the response criterion as opposed to those induced by drugs using pathways such as angiogenesis where disease stabilization is expected rather than shrinkage of tumor.

Colorectal carcinoma metastases in liver: laser-induced interstitial thermotherapy--local tumor control rate and survival data

PURPOSE

To evaluate the local tumor control and survival data for magnetic resonance (MR) imaging-guided laser-induced interstitial thermotherapy (LITT) of colorectal liver metastases.

MATERIALS AND METHODS

MR imaging-guided LITT was performed in 603 patients (mean age, 61.2 years) with 1,801 liver metastases of colorectal cancer. Survival rates were calculated by means of the Kaplan-Meier method. Local tumor control and tumor volume were evaluated with nonenhanced and contrast material-enhanced MR imaging. Indications for the procedure were defined for patients with five or fewer metastases, none of which were larger than 5 cm in diameter. The indications included recurrent liver metastases after partial liver resection in 37.6% of study patients, metastases in both liver lobes in 32.5%, locally nonresectable lesions in 11.3%, general contraindications for surgery in 4.6%, and refusal to undergo surgical resection in 13.9%.

RESULTS

Local recurrence rate at 6-month follow-up was 1.9% (nine of 474) for metastases up to 2 cm in diameter, 2.4% (13 of 539) for metastases 2.1-3.0 cm in diameter, 1.2% (four of 327) for metastases 3.1-4.0 cm in diameter, and 4.4% (13 of 294) for metastases larger than 4 cm in diameter. The mean survival rate for all treated patients, with calculation started on the date of diagnosis of the metastases (which were treated with LITT) was 4.4 years (95% CI: 4.0, 4.8) (1-year survival, 94%; 2-year survival, 77%; 3-year survival, 56%; 5-year survival, 37%). Median survival was 3.5 years (95% CI: 3.0, 3.9). Mean survival after the first LITT treatment was 3.8 years (95% CI: 3.4, 4.2). Median survival was 2.9 years (95% CI: 2.4, 3.3).

CONCLUSION

MR imaging-guided LITT yields high local tumor control and survival rates in well-selected patients with limited liver metastases of colorectal carcinoma.

Response assessment classification in patients with advanced renal cell carcinoma treated on clinical trials

BACKGROUND

The objective of the current study was to evaluate the effect on response assessment classification in patients with metastatic renal cell carcinoma (RCC) using unidimensional (Response Evaluation Criteria in Solid Tumors) and bidimensional (World Health Organization) criteria, including or excluding measurements of the primary renal tumor and using a new index to compensate for the disproportionate effect of large renal tumors relative to their metastases.

METHODS

Fifty-three imaging studies involving a total of 44 patients with metastatic RCC who were treated on clinical trials of interferon-alpha analogue and/or thalidomide were reviewed retrospectively. The best overall response assessment and progression free survival were calculated with both unidimensional and bidimensional tumor measurements. Patients were then stratified into two groups: patients with primary renal tumors in situ and patients who underwent resection of their primary renal tumors. The best overall response and the time to disease progression were calculated based on the sum of measurements (conventional methodology), both including and excluding the primary tumor. A new method of response assessment, the 'normalized lesion index', which equalizes the differences in tumor size for an individual patient, was evaluated and compared with the conventional response assessment.

RESULTS

There was an 11% disagreement rate in the best overall response assessment between unidimensional and bidimensional measurements. The time to progression was 9.2 months measured unidimensionally, compared with 6.4 months assessed bidimensionally. In the group of patients who had primary renal tumors in situ, using the conventional sum of measurements method, the apparent time to progression was an average of 4.2 months longer compared with measurements that did not include the primary renal tumor. The use of the normalized lesion index method resulted in an improved concordance in best overall response assessments and similar time to progression assessments when the primary renal tumor was included compared with patients who did not have primary renal tumors in situ.

CONCLUSIONS

The use of unidimensional measurements in RCC therapy assessment results in significantly different time to progression classification compared with the use of bidimensional measurements. Response assessment classification in patients with RCC is affected by the exclusion or inclusion of measurements of the primary renal tumor. The normalized lesion index warrants further study in assessing response in patients with metastatic RCC and other solid tumor malignancies that often show substantial differences in sizes of measurable lesions.

Estimation of liver tumor volume using a three-dimensional ultrasound volumetric system

The usefulness of a new three-dimensional ultrasound (3DUS) volumetric system developed recently was validated in volume measurement of liver tumor in the present study. The system was used to estimate the volumes of 22 regular phantoms, 25 irregular phantoms and 37 liver tumors from 33 patients. The results showed that the consumed time of measurement with the system ranged from 1 to 15 min, depending on different rotation angles. The measured volumes at different rotation angles all significantly correlated with the true volumes and there were no significant differences among measured volumes at different angles. The measurement error of 3DUS was 0.3% +/- 3.3% in regular phantoms, -0.4% +/- 3.7% in irregular phantoms and 0.9% +/- 11.3% in liver tumors, respectively, as compared with -5.3 +/- 9.4%, 13.6 +/- 28.0% and 15.3 +/- 37.3% for two-dimensional ultrasound, respectively (all p < 0.05). The volume estimation with 3DUS also had significant intraobserver and interobserver reproducibility both in vitro and in vivo. It can be concluded that the new system that we used can greatly reduce the consumed time and manual labor for volume measurement with high accuracy and reproducibility. 3DUS volumetry using the new system is more acceptable and valuable in clinical practice and is expected to be useful for evaluation of the efficacy of tumor therapy in situ in patients with hepatic tumors.

[Volume-effect in radiation therapy part one: volume-effect and tumour]

Volume is an important parameter of radiation therapy. Local control is inversely related to tumor size and the complication rate increases with the importance of the irradiated volume. Although the effect of irradiated volume has been widely reported since the beginning of radiotherapy, it has been less studied than other radiation parameters such as dose, fractionation, or treatment duration. One of the first organ system in which the adverse effect of increased volume was well defined is the skin. Over the last twenty years, numerous mathematical models have been developed for different organs. In this report we will discuss the relation between irradiated volume and tumor control. In a second article we will study the impact of irradiated volume on radiation adverse effects.

CT tumor measurement for therapeutic response assessment: comparison of unidimensional, bidimensional, and volumetric techniques initial observations

PURPOSE

To compare unidimensional, bidimensional, and volumetric techniques for evaluation of treatment response in patients with liver metastases from breast cancer in a phase III clinical trial.

MATERIALS AND METHODS

Helical computed tomographic (CT) studies in 38 patients with liver metastases from breast cancer who were enrolled in a phase III clinical trial were evaluated before treatment and at 6 months after treatment. Two subspecialty radiologists measured all lesions on transverse CT scans with use of electronic calipers according to both unidimensional and bidimensional criteria. Volumetric measurements were made by tracing individual lesions. Measurements of individual lesions were summed to obtain patient response, which was categorized as complete response, disappearance of lesions; partial response, greater than 30% decrease in tumor diameter (unidimensional), greater than 50% reduction in tumor area (bidimensional), or greater than 65% reduction in tumor volume (volumetric); disease progression, greater than 20% increase in tumor diameter, greater than 25% increase in tumor area, or greater than 73% increase in tumor volume: or stable disease (size response other than that of complete response, partial response, or disease progression).

RESULTS

In 37 patients, there was concordant treatment response with use of unidimensional and bidimensional techniques. Volumetric measurement produced results different from those of the unidimensional and bidimensional techniques in 12 and 13 patients, respectively. In six patients with partial response per unidimensional and bidimensional criteria, the response based on the volumetric technique was stable disease. In two patients with stable disease per bidimensional and unidimensional criteria, the response was partial response by volumetric measurement. In four patients with disease progression per bidimensional and unidimensional criteria, the response was stable disease per volumetric criteria.

CONCLUSION

Volumetric measurement of tumor burden gives different results for treatment response compared with that of the unidimensional or bidimensional technique in a considerable proportion of patients.

Radiographic response to neoadjuvant chemotherapy is a predictor of local control and survival in soft tissue sarcomas

BACKGROUND

Downstaging of large soft tissue sarcomas can be accomplished by the use of neoadjuvant chemotherapy (NeoCT). The authors tested the hypothesis that radiographic response to NeoCT predicts improved local control and survival.

METHODS

The authors reviewed the medical records of 65 patients with Stage II or III soft tissue sarcoma (42 extremity, 23 retroperitoneal) who were treated with doxorubicin or ifosfamide-based NeoCT from January 1991 to December 1996. Radiographic response and impact on surgical therapy were determined retrospectively by comparing imaging studies obtained before and after chemotherapy.

RESULTS

The radiographic responses observed were partial response (PR; 22 patients [34%]); minor response (MR; 6 patients [9%]); stable disease (20 patients [31%]); and progressive disease (17 patients [26%]). Downstaging sufficient to decrease the scope of the operation occurred in 13% of the patients, 78% had no change, and 9% had disease progression sufficient to increase the scope of the operation. Patients having any radiographic response (PR or MR) had a higher margin-negative resection rate, a better local recurrence-free survival rate, and a better overall survival rate than did nonresponders.

CONCLUSIONS

The NeoCT regimens used in this study resulted in tumor shrinkage sufficient to impact surgical therapy in a few patients. However, radiographic response predicted improved local control and overall survival rate.