Functional CT for Quantifying Tumor Perfusion in Antiangiogenic Therapy in a Rat Model

Biologically-Based Mathematical Modeling of Tumor Vasculature and Angiogenesis via Time-Resolved Imaging Data

Tumor-associated vasculature is responsible for the delivery of nutrients, removal of waste, and allowing growth beyond 2-3 mm3. Additionally, the vascular network, which is changing in both space and time, fundamentally influences tumor response to both systemic and radiation therapy. Thus, a robust understanding of vascular dynamics is necessary to accurately predict tumor growth, as well as establish optimal treatment protocols to achieve optimal tumor control. Such a goal requires the intimate integration of both theory and experiment. Quantitative and time-resolved imaging methods have emerged as technologies able to visualize and characterize tumor vascular properties before and during therapy at the tissue and cell scale. Parallel to, but separate from those developments, mathematical modeling techniques have been developed to enable in silico investigations into theoretical tumor and vascular dynamics. In particular, recent efforts have sought to integrate both theory and experiment to enable data-driven mathematical modeling. Such mathematical models are calibrated by data obtained from individual tumor-vascular systems to predict future vascular growth, delivery of systemic agents, and response to radiotherapy. In this review, we discuss experimental techniques for visualizing and quantifying vascular dynamics including magnetic resonance imaging, microfluidic devices, and confocal microscopy. We then focus on the integration of these experimental measures with biologically based mathematical models to generate testable predictions.

Correlation study between flash dual source CT perfusion imaging and regional lymph node metastasis of non-small cell lung cancer

Background

To explore the correlation of flash dual source computed tomography perfusion imaging (CTPI) and regional lymph node metastasis of non-small cell lung cancer (NSCLC), and to evaluate the value of CT perfusion parameters in predicting regional lymph node metastasis of NSCLC.

Methods

120 consecutive patients with NSCLC confirmed by postoperative histopathology were underwent flash dual source CT perfusion imaging in pre-operation. The CT perfusion parameters of NSCLC, such as blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability (PMB) were obtained by the image post-processing. Then microvessel density (MVD), luminal vascular number (LVN), luminal vascular area (LVA) and luminal vascular perimeter (LVP) of NSCLC were counted by immunohistochemistry. These cases were divided into group A (patients with lymph node metastasis, 58 cases) and group B (patients without lymph node metastasis, 62 cases) according to their pathological results. The CT perfusion parameters and the microvessel parameters were contrastively analysed between the two groups. Receiver operating characteristic (ROC) curve was used to assess the diagnostic efficiency of CT perfusion parameters in predicting regional lymph node metastasis of NSCLC in pre-operation.

Results

Group A presented significantly lower LVA, BF and higher MTT, PMB than Group B (P < 0.05), while BV, LVN, LVP and MVD were no significant difference (P > 0.05). Correlation analysis showed that BF was correlated with LVA and LVP (P < 0.05), while BV, MTT and PMB were not correlated with LVN, LVA and LVP (P > 0.05). All the perfusion parameters were not correlated with MVD. According to the ROC curve analysis, when BF < 85.16 ml/100 ml/min as a cutoff point to predict regional lymph node metastasis of NSCLC, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 60.8, 81.7, 71.5, 75.6 and 69.5% respectively.

Conclusion

Flash dual source CT perfusion imaging can non-invasively indicate the luminal vascular structure of tumor and BF can be used as one of the important indexes in predicting regional lymph node metastasis of NSCLC in pre-operation.

Can Dynamic Contrast-Enhanced CT Quantify Perfusion in a Stimulated Muscle of Limited Size? A Rat Model

BACKGROUND

Muscle injury may result in damage to the vasculature, rendering it unable to meet the metabolic demands of muscle regeneration and healing. Therefore, therapies frequently aim to maintain, restore, or improve blood supply to the injured muscle. Although there are several options to assess the vascular outcomes of these therapies, few are capable of spatially assessing perfusion in large volumes of tissue.

QUESTIONS/PURPOSES

Can dynamic contrast-enhanced CT (DCE-CT) imaging acquired with a clinical CT scanner be used in a rat model to quantify perfusion in the anterior tibialis muscle at spatially relevant volumes, as assessed by (1) the blood flow rate and tissue blood volume in the muscle after three levels of muscle stimulation (low, medium, and maximum) relative to baseline as determined by the non-stimulated contralateral leg; and (2) how do these measurements compare with those obtained by the more standard approach of microsphere perfusion?

METHODS

The right anterior tibialis muscles of adult male Sprague Dawley rats were randomized to low- (n = 10), medium- (n = 6), or maximum- (n = 3) level (duty cycles of 2.5%, 5.0%, and 20%, respectively) nerve electrode coupled muscle stimulation directly followed by DCE-CT imaging. Tissue blood flow and blood volume maps were created using commercial software and volumetrically measured using NIH software. Although differences in blood flow were detectable across the studied levels of muscle stimulation, a review of the evidence suggested the absolute blood flow quantified was underestimated. Therefore, at a later date, a separate set of adult male Sprague Dawley rats were randomized for microsphere perfusion (n = 7) to define blood flow in the animal model with an accepted standard. With this technique, intra-arterial particles sized to freely flow in blood but large enough to lodge in tissue capillaries were injected. Simultaneously, blood sampling at a fixed flow rate was simultaneously performed to provide a fixed blood flow rate sample. The tissues of interest were then explanted and assessed for the total number of particles per tissue volume. Tissue blood flow rate was then calculated based on the particle count ratio within the reference sample. Note that a tissue's blood volume cannot be calculated with this method. Comparison analysis to the non-stimulated baseline leg was performed using two-tailed paired student t-test. An ANOVA was used to compare difference between stimulation groups.

RESULTS

DCE-CT measured (mean ± SD) increasing tissue blood flow differences in stimulated anterior tibialis muscle at 2.5% duty cycle (32 ± 5 cc/100 cc/min), 5.0% duty cycle (46 ± 13 cc/100 cc/min), and 20% duty cycle (73 ± 3 cc/100 cc/min) compared with the paired contralateral non-stimulated anterior tibialis muscle (10 ± 2 cc/100 cc/min, mean difference 21 cc/100 cc/min [95% CI 17.08 to 25.69]; 9 ± 1 cc/100 cc/min, mean difference 37 cc/100 cc/min [95% CI 23.06 to 50.11]; and 11 ± 2 cc/100 cc/min, mean difference 62 cc/100 cc/min [95% CI 53.67 to 70.03]; all p < 0.001). Similarly, DCE-CT showed increasing differences in tissue blood volumes within the stimulated anterior tibialis muscle at 2.5% duty cycle (23.2 ± 4.2 cc/100 cc), 5.0% duty cycle (39.2 ± 7.2 cc/100 cc), and 20% duty cycle (52.5 ± 13.1 cc/100 cc) compared with the paired contralateral non-stimulated anterior tibialis muscle (3.4 ± 0.7 cc/100 cc, mean difference 19.8 cc/100 cc [95% CI 16.46 to 23.20]; p < 0.001; 3.5 ± 0.4 cc/100 cc, mean difference 35.7 cc/100 cc [95% CI 28.44 to 43.00]; p < 0.001; and 4.2 ± 1.3 cc/100 cc, mean difference 48.3 cc/100 cc [95% CI 17.86 to 78.77]; p = 0.010). Microsphere perfusion measurements also showed an increasing difference in tissue blood flow in the stimulated anterior tibialis muscle at 2.5% duty cycle (62 ± 43 cc/100 cc/min), 5.0% duty cycle (89 ± 52 cc/100 cc/min), and 20% duty cycle (313 ± 269 cc/100 cc/min) compared with the paired contralateral non-stimulated anterior tibialis muscle (8 ± 4 cc/100 cc/min, mean difference 55 cc/100 cc/min [95% CI 15.49 to 94.24]; p = 0.007; 9 ± 9 cc/100 cc/min, mean difference 79 cc/100 cc/min [95% CI 33.83 to 125.09]; p = 0.003; and 18 ± 18 cc/100 cc/min, mean difference 295 cc/100 cc/min [95% CI 8.45 to 580.87]; p = 0.023). Qualitative comparison between the methods suggests that DCE-CT values underestimate tissue blood flow with a post-hoc ANOVA showing DCE-CT blood flow values within the 2.5% duty cycle group (32 ± 5 cc/100 cc/min) to be less than the microsphere perfusion value (62 ± 43 cc/100 cc/min) with a mean difference of 31 cc/100 cc/min (95% CI 2.46 to 60.23; p = 0.035).

CONCLUSIONS

DCE-CT using a clinical scanner is a feasible modality to measure incremental changes of blood flow and tissue blood volume within a spatially challenged small animal model. Care should be taken in studies where true blood flow values are needed, as this particular small-volume muscle model suggests true blood flow is underestimated using the specific adaptions of DCE-CT acquisition and image processing chosen.

CLINICAL RELEVANCE

CT perfusion is a clinically available modality allowing for translation of science from bench to bedside. Adapting the modality to fit small animal models that are relevant to muscle healing may hasten time to clinical utility.

Correlation study between dual source CT perfusion imaging and the microvascular composition of solitary pulmonary nodules

OBJECTIVE

To explore the correlation between dual source computed tomography perfusion imaging (CTPI) and microvascular parameters, and evaluate the value of CTPI in the differential diagnosis of solitary pulmonary nodule (SPN).

METHODS

65 consecutive patients with SPN who successfully underwent pre-operative CT perfusion imaging with dual source CT and received a final diagnosis by postoperative pathology. The cases were divided into malignant, benign and inflammatory groups according to the pathological results. CT perfusion parameters, such as blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PMB) were obtained by performing CTPI of SPNs. The postoperative specimens of SPNs were immunohistochemically stained for CD34 and SMA to detect microvessel density (MVD) and luminal vascular parameters, such as luminal vascular number (LVN), luminal vascular area (LVA) and luminal vascular perimeter (LVP). The receiver operating characteristic (ROC) curve was used to assess the diagnostic efficiency of CT perfusion parameter in diagnosing malignant SPNs.

RESULTS

In these 65 cases, malignant, benign and inflammatory SPNs were respectively 39, 14 and 12 cases. Significant difference was observed in LVN/MVD, LVA and LVP among the three groups (P < 0.05). The correlation between CT perfusion parameters (BF, BV and PMB) and the luminal vascular parameters was stronger than that with MVD (P < 0.05). PMB has the strongest correlation with LVN/MVD. Using BF≥60ml/100ml/min, BV≥6.34ml/100ml and PMB≥13.35ml/100 ml/min for the diagnosis, the area under the curve (AUC) of the ROC curve was 0.760, the sensitivity was 82% and the specificity was 61%.

CONCLUSIONS

The main indicators reflecting blood perfusion of SPN are the degree of lumen or maturity of microvessels (LVN, LVA and LVP), not just the number of microvessels (e.g. MVD). CT perfusion imaging can be used as an important method to non-invasively evaluate tumour angiogenesis and help to distinguish malignant SPNs from benign and inflammatory SPNs.

Correlation between pathologic features and perfusion CT of renal cancer: A feasibility study

Objectives

The computerized tomography with perfusion technique (pCT) has proved to have some potentialities in the oncologic field as a possible tool to identify neoangiogenesis in vivo. The purpose of the present job is to test the correlations existing between perfusion data and pathologic features in the evaluation of vascularization in kidney cancer.

Methods

6 patients with clinical diagnosis of renal tumor awaiting surgical treatment underwent preoperatively pCT scans. Axial images encompassing the greatest diameter of the cancer were compared with the respective histological sections.

Results

A correlation between tumor histological subtype and perfusion index was observed and shown. Moreover, clear cell RCC of different Fuhrman grades showed statistically significant differences in perfusion values (T test). Specifically, high perfusion indexes were associated with high density of microvessels with abnormal architecture at the microscopic evaluation of tumor specimen. Conversely, lower perfusion index were detected in tumors with lower microvascular density.

Conclusions

pCT scans can provide significant data on tumor angiogenesis and, eventually, suggest tumor histological subtype. The possibility of identifying preoperatively tumor histotype can be of particular relevance in patients with small renal tumors, suitable for minimally-invasive surgery or active surveillance program.

β-elemene enhances anticancer and anti-metastatic effects of osteosarcoma of ligustrazine in vitro and in vivo

The present study aimed to determine the anticancer effects of the combination of β-elemene and ligustrazine in vitro as well as in in vivo. Following evaluation using an MTT assay, β-elemene, ligustrazine and the β-elemene-ligustrazine combination treatments all exhibited the capacity to inhibit the growth of OS-732 cells, with inhibitory rates of 43.3, 54.4, and 75.0%, respectively. Using a flow cytometry assay, it was determined that the β-elemene-ligustrazine combination possessed the highest apoptotic rate (30.6%). Furthermore, β-elemene-ligustrazine combination treatment resulted in the highest downregulation of G protein-coupled receptor 124, vascular endothelial growth factor, matrix metallopeptidase (MMP)-2 and MMP-9 mRNA, and protein expression levels. In addition, the combined treatment led to an increase in the mRNA and protein expression of endostatin, TIMP metallopeptidase inhibitor (TIMP)-1 and TIMP-2 in OS-732 cells. Additionally, β-elemene-ligustrazine caused a decrease in nuclear factor-κB, interleukin-8, C-X-C motif chemokine receptor 4 and urokinase-type plasminogen activator mRNA expression, as well as an increase in caspase-3, caspase-8, and caspase-9 mRNA expression. In vivo, the β-elemene-ligustrazine combination was able to reduce the weight and the bulk of the tumor in BALB/c-nu/nu nude mice compared with any other group. All the results described above regarding changes to mRNA and protein expression were further confirmed in vivo in the tumor tissue of mice. The results of the present study have suggested that the combination of β-elemene-ligustrazine exhibits greater anticancer effects compared with β-elemene- or ligustrazine-alone treatment.

Relative Computed Tomography (CT) Enhancement Value for the Assessment of Microvascular Architecture in Renal Cell Carcinoma

BACKGROUND To investigate the correlation between the relative computed tomography (CT) enhancement value and the microvascular architecture in different pathologic subtypes of renal cell carcinoma (RCC). MATERIAL AND METHODS This retrospective study included 55 patients with pathologically confirmed RCC. Immunohistochemistry for CD34 was performed for all surgical specimens. Microvascular architecture parameters (density, area, diameter, and perimeter) for the microvessels and the microvessels with lumen were determined. The CT scan was performed during arterial phase or venous phase. The correlation of parameters on CT and tumor angiogenesis was investigated. RESULTS Density of microvessels showed a positive correlation with CT values of tumors, ratios of tumor to cortex, and differences of tumor and medulla, but no correlation with CT value ratio of tumor to aorta or tumor to medulla. CT parameters were positively correlated with microvascular parameters. However, no CT parameter differences between hypo-vascular clear cell RCC and papillary RCC was observed. Strikingly, the density and area of the microvessels were significantly higher in hypo-vascular clear cell RCC than that in papillary RCC, while the density of the microvessels with lumen in the cyst-present RCC was significantly higher than that in the cyst-absent RCC. The values (especially those of microvessels with lumen) of area density, diameter, and perimeter were higher in the capsule-absent RCC than in the capsule-present RCC. CONCLUSIONS The relative CT enhancement value of RCC was associated with vascular architecture parameters including density, area, and perimeter. Quantitative and semi-quantitative parameters on enhanced CT may shed some light on tumor vasculature and function as indicators of the biological behavior of RCC.

Perfusion parameters as potential imaging biomarkers for the early prediction of radiotherapy response in a rat tumor model

PURPOSE

We aimed to compare various tumor-related radiologic morphometric changes and computed tomography (CT) perfusion parameters before and after treatment, and to determine the optimal imaging assessment technique for the prediction of early response in a rat tumor model treated with radiotherapy.

METHODS

Among paired tumors of FN13762 murine breast cancer cells implanted bilaterally in the necks of eight Fischer rats, tumors on the right side were treated with a single 20 Gy dose of radiotherapy. Perfusion CT studies were performed on day 0 before radiotherapy, and on days 1 and 5 after radiotherapy. Variables based on the size, including the longest diameter, tumor area, and volume, were measured. Quantitative perfusion analysis was performed for the whole tumor volume and permeabilities and blood volumes (BVs) were obtained. The area under the curve (AUC) difference in the histograms of perfusion parameters and texture analyses of uniformity and entropy were quantified. Apoptotic cell density was measured on pathology specimens immediately after perfusion imaging on day 5.

RESULTS

On day 1 after radiotherapy, differences in size between the irradiated and nonirradiated tumors were not significant. In terms of percent changes in the uniformity of permeabilities between tumors before irradiation and on day 1 after radiotherapy, the changes were significantly higher in the irradiated tumors than in the nonirradiated tumors (0.085 [-0.417, 0.331] vs. -0.131 [-0.536, 0.261], respectively; P = 0.042). The differences in AUCs of the histogram of voxel-by-voxel vascular permeability and BV in tumors between day 0 and day 1 were significantly higher in treated tumors compared with the control group (permeability, 21.4 [-2.2, 37.5] vs. 9.5 [-8.9, 33.8], respectively, P = 0.030; BV, 52.9 [-6186.0, 419.2] vs. 11.9 [-198.3, 346.7], respectively, P = 0.049). Apoptotic cell density showed a significantly positive correlation with the AUC difference of BV, the percent change of uniformity in permeability and BV (r=0.202, r=0.644, and r=0.706, respectively).

CONCLUSION

By enabling earlier tumor response prediction than morphometric evaluation, the histogram analysis of CT perfusion parameters appears to have a potential in providing prognostic predictive information in an irradiated rat model.

Monitoring outcomes in intrahepatic cholangiocarcinoma patients following hepatic resection

Intrahepatic cholangiocarcinoma (iCCA) is one of the fatal gastrointestinal cancers with increasing incidence and mortality. Although surgery offers the only potential for cure in iCCA patients, the prognosis is not optimal with low overall survival rate and high disease recurrence. Hence, adjuvant therapy is generally recommended in the management of high-risk patients. Identifying factors associated with disease recurrence and survival of the iCCA patients after resection will improve understanding of disease prognosis and help in selecting patients who will benefit from surgical resection or stratifying them for clinical trials. Despite development of new methods for early detection of tumor recurrence, effective prognostic models and nomograms, and recent advances in management, significant challenges remain in improving the prognosis of iCCA patients.

CT Perfusion for Early Response Evaluation of Radiofrequency Ablation of Focal Liver Lesions: First Experience

PURPOSE

To investigate the value of perfusion CT (P-CT) for early assessment of treatment response in patients undergoing radiofrequency ablation (RFA) of focal liver lesions.

METHODS AND MATERIALS

20 consecutive patients (14 men; mean age 64 ± 14) undergoing P-CT within 24 h after RFA of liver metastases (n = 10) or HCC (n = 10) were retrospectively included. Two readers determined arterial liver perfusion (ALP, mL/min/100 mL), portal liver perfusion (PLP, mL/min/100 mL), and hepatic perfusion index (HPI, %) in all post-RFA lesions by placing a volume of interest in the necrotic central (CZ), the transition (TZ), and the surrounding parenchymal (PZ) zone. Patients were classified into complete responders (no residual tumor) and incomplete responders (residual/progressive tumor) using imaging follow-up with contrast-enhanced CT or MRI after a mean of 57 ± 30 days. Prediction of treatment response was evaluated using the area under the curve (AUC) from receiver operating characteristic analysis.

RESULTS

Mean ALP/PLP/HPI of both readers were 4.8/15.4/61.2 for the CZ, 9.9/16.8/66.3 for the TZ and 20.7/29.0/61.8 for the PZ. Interreader agreement of HPI was fair for the CZ (intraclass coefficient 0.713), good for the TZ (0.813), and excellent for the PZ (0.920). For both readers, there were significant differences in HPI of the CZ and TZ between responders and nonresponders (both, P < 0.05). HPI of the TZ showed the highest AUC (0.911) for prediction of residual tumor, suggesting a cut-off value of 76 %.

CONCLUSION

Increased HPI of the transition zone assessed with P-CT after RFA might serve as an early quantitative biomarker for residual tumor in patients with focal liver lesions.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging With Gadolinium Ethoxybenzyl Diethylenetriamine Pentaacetic Acid for Quantitative Assessment of Vascular Effects on Hepatocellular-Carcinoma Lesions Treated by Transarterial Chemoembolization or Radiofrequency Ablation

PURPOSE

The aim of this study was to investigate the role of dynamic contrast-enhanced magnetic resonance imaging (MRI) in evaluation of blood flow changes related to transarterial chemoembolization (TACE) and radiofrequency ablation (RFA) procedures in patients with hepatocellular carcinoma (HCC) lesions.

METHODS

Fifty-four patients, with biopsy-proven HCC, who underwent TACE or RFA, were evaluated, 1 month after treatment, with upper abdominal MRI examination. Multiplanar T2-weighted, T1-weighted, and dynamic contrast-enhanced sequences were acquired. Dedicated perfusion software (T1 Perfusion Package, Viewforum; Philips Medical Systems, The Netherlands) was used to generate color permeability maps. After placing regions of interest in normal hepatic parenchyma, in successfully treated lesions, and in area of recurrence, the following perfusion parameters were calculated and statistically analyzed: relative arterial, venous, and late enhancement; maximum enhancement; maximum relative enhancement, and time to peak.

RESULTS

Twenty-one of 54 patients had residual disease, and perfusion parameters values measured within tumor tissue were: relative arterial enhancement median, 42%; relative venous enhancement median, 69%; relative late enhancement median, 57.7%; maximum enhancement median, 749.6%; maximum relative enhancement median, 69%; time to peak median, 81.1 seconds. As for all the evaluated parameters, a significant difference (P < 0.05) was found between residual viable tumor tissue and effective treated lesions.

CONCLUSIONS

Dynamic contrast-enhanced MRI represents a complementary noninvasive tool that may offer quantitative and qualitative information about HCC lesions treated with TACE and RFA.

Perfusion computed tomography in renal cell carcinoma

Various imaging modalities are available for the diagnosis, staging and response evaluation of patients with renal cell carcinoma (RCC). While contrast enhanced computed tomography (CT) is used as the standard of imaging for size, morphological evaluation and response assessment in RCC, a new functional imaging technique like perfusion CT (pCT), goes down to the molecular level and provides new perspectives in imaging of RCC. pCT depicts regional tumor perfusion and vascular permeability which are indirect parameters of tumor angiogenesis and thereby provides vital information regarding tumor microenvironment. Also response evaluation using pCT may predate the size criteria used in Response Evaluation Criteria in Solid Tumors, as changes in the perfusion occurs earlier following tissue kinase inhibitors before any actual change in size. This may potentially help in predicting prognosis, better selection of therapy and more accurate and better response evaluation in patients with RCC. This article describes the techniques and role of pCT in staging and response assessment in patients with RCCs.

Quantitative radiology: applications to oncology

Oncologists, clinician-scientists, and basic scientists collect computed tomography, magnetic resonance, and positron emission tomography images in the process of caring for patients, managing clinical trials, and investigating cancer biology. As we have developed more sophisticated means for noninvasively delineating and characterizing neoplasms, these image data have come to play a central role in oncology. In parallel, the increasing complexity and volume of these data have necessitated the development of quantitative methods for assessing tumor burden, and by proxy, disease-free survival.

Dynamic contrast-enhanced micro-computed tomography correlates with 3-dimensional fluorescence ultramicroscopy in antiangiogenic therapy of breast cancer xenografts

OBJECTIVES

Dynamic contrast-enhanced (DCE) micro-computed tomography (micro-CT) has emerged as a valuable imaging tool to noninvasively obtain quantitative physiological biomarkers of drug effect in preclinical studies of antiangiogenic compounds. In this study, we explored the ability of DCE micro-CT to assess the antiangiogenic treatment response in breast cancer xenografts and correlated the results to the structural vessel response obtained from 3-dimensional (3D) fluorescence ultramicroscopy (UM).

MATERIAL AND METHODS

Two groups of tumor-bearing mice (KPL-4) underwent DCE micro-CT imaging using a fast preclinical dual-source micro-CT system (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany). Mice were treated with either a monoclonal antibody against the vascular endothelial growth factor or an unspecific control antibody. Changes in vascular physiology were assessed measuring the mean value of the relative blood volume (rBV) and the permeability-surface area product (PS) in different tumor regions of interest (tumor center, tumor periphery, and total tumor tissue). Parametric maps of rBV were calculated of the tumor volume to assess the intratumoral vascular heterogeneity. Isotropic 3D UM vessel scans were performed from excised tumor tissue, and automated 3D segmentation algorithms were used to determine the microvessel density (MVD), relative vessel volume, and vessel diameters. In addition, the accumulation of coinjected fluorescence-labeled trastuzumab was quantified in the UM tissue scans to obtain an indirect measure of vessel permeability. Results of the DCE micro-CT were compared with corresponding results obtained by ex vivo UM. For validation, DCE micro-CT and UM parameters were compared with conventional histology and tumor volume.

RESULTS

Examination of the parametric rBV maps revealed significantly different patterns of intratumoral blood supply between treated and control tumors. Whereas control tumors showed a characteristic vascular rim pattern with considerably elevated rBV values in the tumor periphery, treated tumors showed a widely homogeneous blood supply. Compared with UM, the physiological rBV maps showed excellent agreement with the spatial morphology of the intratumoral vascular architecture. Regional assessment of mean physiological values exhibited a significant decrease in rBV (P < 0.01) and PS (P < 0.05) in the tumor periphery after anti-vascular endothelial growth factor treatment. Structural validation with UM showed a significant reduction in reduction of relative vessel volume (rVV) (P < 0.01) and MVD (P < 0.01) in the corresponding tumor region. The reduction in rBV correlated well with the rVV (R = 0.73 for single values and R = 0.95 for mean values). Spatial maps of antibody penetration showed a significantly reduced antibody accumulation (P < 0.01) in the tumor tissue after treatment and agreed well with the physiological change of PS. Examination of vessel diameters revealed a size-dependent antiangiogenic treatment effect, which showed a significant reduction in MVD (P < 0.001) for vessels with diameters smaller than 25 μm. No treatment effect was observed by tumor volume.

CONCLUSIONS

Noninvasive DCE micro-CT provides valuable physiological information of antiangiogenic drug effect in the intact animal and correlates with ex vivo structural analysis of 3D UM. The combined use of DCE micro-CT with UM constitutes a complementary imaging toolset that can help to enhance our understanding of antiangiogenic drug mechanisms of action in preclinical drug research.

A correlation of computed tomography perfusion and histopathology in tumor edges of hepatocellular carcinoma

BACKGROUND

The peripheral morphologic characteristics of hepatocellular carcinoma (HCC) reflect tumor growth patterns. Computed tomography (CT) perfusion is a new method to analyze hemodynamic changes in tissues. We assessed the relationship between CT perfusion and histopathologic findings in the periphery of HCC lesions.

METHODS

Non-contrast CT, enhanced dual-phase CT, and CT perfusion were performed on 77 subjects (47 patients and 30 controls). Based on the imaging findings of enhanced dual-phase CT, the tumor edges were classified into three types: type I (sharp); type II (blurry); and type III (mixed). The CT perfusion parameters included hepatic blood flow, hepatic arterial fraction, hepatic arterial perfusion, and hepatic portal perfusion. The tissue sections from resected specimens were subjected to routine hematoxylin and eosin staining and immunohistochemical staining for CD34. The correlations between microvessel density (MVD) and the CT perfusion parameters were analyzed using Pearson's product-moment correlation coefficient. Changes in the perfusion parameters in tumor edges of different tumor types were evaluated.

RESULTS

Type I (sharp): the pathologic findings showed fibrous connective tissue capsules in the tumor edges, and an MVD ≤30/mm2. Type II (blurry): the histology showed that the edges were clear with no capsules and an MVD>30/mm2. Type III (mixed): the pathology was similar to that of types I and II, and an MVD>30/mm2. Hepatic blood flow, hepatic arterial fraction, hepatic arterial perfusion, and hepatic portal perfusion were significantly increased in the tumor edges of HCC patients compared to those of the controls (P<0.05). The correlation between CT perfusion parameters and MVD was higher in blurry tumor edges of type II than in those of types I or III.

CONCLUSION

CT perfusion imaging of tumor edges may be helpful in revealing histopathological features, and indirectly reflect angiogenic changes of HCCs.

Tumour-related neoangiogenesis: functional dynamic perfusion computed tomography for diagnosis and treatment efficacy assessment in hepatocellular carcinoma

BACKGROUND

Aim of the study was to determine the value of perfusion computed tomography in the quantitative assessment of tumour-related neoangiogenesis for the diagnosis and treatment of hepatocellular carcinoma lesions.

METHODS

Overall, 47 consecutive patients with cirrhotic liver disease, with a high risk of hepatocellular carcinoma, and undergoing standard surveillance (six-month intervals) were eligible for inclusion in this prospective study; based on Barcelona Clinic Liver Cancer guidelines, 27 patients were enrolled. Perfusion computed tomography was performed in 29 biopsy-proven hepatocellular carcinoma lesions before and after treatment with transarterial chemoembolization or radiofrequency ablation. The dynamic study was performed with a 256-slice multidetector-computed tomography scanner; the following parameters were measured: hepatic perfusion, arterial perfusion, blood volume, hepatic perfusion index, and time-to-peak in all patients.

RESULTS

Hepatocellular carcinoma lesions had the following median perfusion values: perfusion 46.3mL/min/100g; blood volume 20.4mL/100mg; arterial perfusion 42.9mL/min; hepatic perfusion index 92.5%; time to peak 18.7s. Significantly lower perfusion values were obtained in correctly treated lesions or surrounding parenchyma than in viable hepatocellular carcinoma tissue.

CONCLUSIONS

In hepatocellular carcinoma, perfusion computed tomography could contribute to a non-invasive quantification of tumour blood supply related to the formation of new arterial structures, and enable the assessment of therapeutic response.

Quantitative evaluation of CT-perfusion map as indicator of tumor response to transarterial chemoembolization and radiofrequency ablation in HCC patients

PURPOSE

To assess if radiofrequency ablation (RFA) and transarterial chemoembolization (TACE) may influence the evaluation of perfusion parameters obtained with CT-perfusion (CT-p) in HCC treated patients.

MATERIALS AND METHODS

Thirty-three consecutive cirrhotic patients with biopsy-proven diagnosis of HCC lesions and candidates to TACE or RFA were included. The CT-p study of hepatic parenchyma and of treated lesions was performed about 1 month after treatment on 16 multidetector CT after injection of 50mL of non ionic contrast agent (350mg I/mL) at a flow rate of 6mL/s acquiring 40 dynamic scans. A dedicated perfusion software which generated a quantitative map of arterial and portal perfusion by means of colour scale was employed.The following perfusion parameters were assessed before and after RFA or TACE treatment: hepatic perfusion (HP), arterial perfusion (AP), blood volume (BV), time to peak (TTP), hepatic perfusion index (HPI).

RESULTS

A complete treatment was obtained in 16 cases and incomplete treatment in the 17 remaining cases. The perfusion data of completely treated lesions were: HP 10.2±6.3; AP 10.4±7; BV 4.05±4.8; TTP 38.9±4.2; HPI 9.9±9.2, whereas in partially treated lesions were: HP 43.2±15.1mL/s/100g; AP 38.7±8.8mL/min; BV 20.7±9.5mL/100mg; TTP 24±3.7s; HPI 61.7±7.5%. In adjacent cirrhotic parenchyma, the parameters of all evaluated patients were: HP 13.2±4; AP 12.3±3.4; BV 11.8±2.8; TTP 43.9±2.9; and HPI 17.1±9.8. A significant difference (P<0.001) was found for all parameters between residual viable tumor tissue (P<0.001) compared to successfully treated lesion due to the presence of residual arterial vascular structure in viable portion of treated HCC.

CONCLUSION

According to our results, CT-p evaluation is not influenced by TACE or RFA treatments, thus representing a feasible technique that allows a reproducible quantitative evaluation of treatment response in HCC patients.

Micro-CT of rodents: state-of-the-art and future perspectives

Micron-scale computed tomography (micro-CT) is an essential tool for phenotyping and for elucidating diseases and their therapies. This work is focused on preclinical micro-CT imaging, reviewing relevant principles, technologies, and applications. Commonly, micro-CT provides high-resolution anatomic information, either on its own or in conjunction with lower-resolution functional imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). More recently, however, advanced applications of micro-CT produce functional information by translating clinical applications to model systems (e.g., measuring cardiac functional metrics) and by pioneering new ones (e.g. measuring tumor vascular permeability with nanoparticle contrast agents). The primary limitations of micro-CT imaging are the associated radiation dose and relatively poor soft tissue contrast. We review several image reconstruction strategies based on iterative, statistical, and gradient sparsity regularization, demonstrating that high image quality is achievable with low radiation dose given ever more powerful computational resources. We also review two contrast mechanisms under intense development. The first is spectral contrast for quantitative material discrimination in combination with passive or actively targeted nanoparticle contrast agents. The second is phase contrast which measures refraction in biological tissues for improved contrast and potentially reduced radiation dose relative to standard absorption imaging. These technological advancements promise to develop micro-CT into a commonplace, functional and even molecular imaging modality.

Correlation of intra-tumor 18F-FDG uptake heterogeneity indices with perfusion CT derived parameters in colorectal cancer

METHODS

Thirty patients with proven colorectal cancer prospectively underwent integrated 18F-FDG PET/DCE-CT to assess the metabolic-flow phenotype. Both CT blood flow parametric maps and PET images were analyzed. Correlations between PET heterogeneity and perfusion CT were assessed by Spearman's rank correlation analysis.

RESULTS

Blood flow visualization provided by DCE-CT images was significantly correlated with 18F-FDG PET metabolically active tumor volume as well as with uptake heterogeneity for patients with stage III/IV tumors (|ρ|:0.66 to 0.78; p-value<0.02).

CONCLUSION

The positive correlation found with tumor blood flow indicates that intra-tumor heterogeneity of 18F-FDG PET accumulation reflects to some extent tracer distribution and consequently indicates that 18F-FDG PET intra-tumor heterogeneity may be associated with physiological processes such as tumor vascularization.

Dual-energy computed tomography for the assessment of early treatment effects of regorafenib in a preclinical tumor model: comparison with dynamic contrast-enhanced CT and conventional contrast-enhanced single-energy CT

OBJECTIVES

The potential diagnostic value of dual-energy computed tomography (DE-CT) compared to dynamic contrast-enhanced CT (DCE-CT) and conventional contrast-enhanced CT (CE-CT) in the assessment of early regorafenib treatment effects was evaluated in a preclinical setting.

METHODS

A rat GS9L glioma model was examined with contrast-enhanced dynamic DE-CT measurements (80 kV/140 kV) for 4 min before and on days 1 and 4 after the start of daily regorafenib or placebo treatment. Tumour time-density curves (0-240 s, 80 kV), DE-CT (60 s) derived iodine maps and the DCE-CT (0-30 s, 80 kV) based parameters blood flow (BF), blood volume (BV) and permeability (PMB) were calculated and compared to conventional CE-CT (60 s, 80 kV).

RESULTS

The regorafenib group showed a marked decrease in the tumour time-density curve, a significantly lower iodine concentration and a significantly lower PMB on day 1 and 4 compared to baseline, which was not observed for the placebo group. CE-CT showed a significant decrease in tumour density on day 4 but not on day 1. The DE-CT-derived iodine concentrations correlated with PMB and BV but not with BF.

CONCLUSIONS

DE-CT allows early treatment monitoring, which correlates with DCE-CT. Superior performance was observed compared to single-energy CE-CT.

KEY POINTS

• Regorafenib treatment response was evaluated by CT in a rat tumour model. • Dual-energy contrast-enhanced CT allows early treatment monitoring of targeted anti-tumour therapies. • Dual-energy CT showed higher diagnostic potential than conventional contrast enhanced single-energy CT. • Dual-energy CT showed diagnostic potential comparable to dynamic contrast-enhanced CT. • Dual-energy CT is a promising method for efficient clinical treatment response evaluation.

Feasibility study of CT perfusion imaging for prostate carcinoma

OBJECTIVE

The aim of this feasibility study was to obtain initial data with which to assess the efficiency of perfusion CT imaging (CTpI) and to compare this with magnetic resonance imaging (MRI) in the diagnosis of prostate carcinoma.

MATERIALS AND METHODS

This prospective study involved 25 patients with prostate carcinoma undergoing MRI and CTpI. All analyses were performed on T2-weighted images (T2WI), apparent diffusion coefficient (ADC) maps, diffusion-weighted images (DWI) and CTp images. We compared the performance of T2WI combined with DWI and CTp alone. The study was approved by the local ethics committee, and written informed consent was obtained from all patients.

RESULTS

Tumours were present in 87 areas according to the histopathological results. The diagnostic performance of the T2WI+DWI+CTpI combination was significantly better than that of T2WI alone for prostate carcinoma (P < 0.001). The diagnostic value of CTpI was similar to that of T2WI+DWI in combination. There were statistically significant differences in the blood flow and permeability surface values between prostate carcinoma and background prostate on CTp images.

CONCLUSION

CTp may be a valuable tool for detecting prostate carcinoma and may be preferred in cases where MRI is contraindicated. If this technique is combined with T2WI and DWI, its diagnostic value is enhanced.

KEY POINTS

Perfusion CT is a helpful technique for prostate carcinoma diagnosis. •Colour maps allow easy and rapid visual assessment of the functional changes. Colour maps of prostate carcinoma provide information about in vivo tumoral vascularity. CTp images may be added into routine radiological examinations. CTp provides guidance for histopathological correlation if biopsy is scheduled.

Multi-parametric MRI of rectal cancer - do quantitative functional MR measurements correlate with radiologic and pathologic tumor stages?

PURPOSE

The purpose of this study is two-fold. First, to evaluate, whether functional rectal MRI techniques can be analyzed in a reproducible manner by different readers and second, to assess whether different clinical and pathologic T and N stages can be differentiated by functional MRI measurements.

MATERIALS AND METHODS

54 patients (38 men, 16 female; mean age 63.2 ± 12.2 years) with pathologically proven rectal cancer were included in this retrospective IRB-approved study. All patients were referred for a multi-parametric MRI protocol on a 3 Tesla MR-system, consisting of a high-resolution, axial T2 TSE sequence, DWI and perfusion imaging (plasma flow -s PFTumor) prior to any treatment. Two experienced radiologists evaluated the MRI measurements, blinded to clinical data and outcome. Inter-reader correlation and the association of functional MRI parameters with c- and p-staging were analyzed.

RESULTS

The inter-reader correlation for lymph node (ρ 0.76-0.94; p<0.0002) and primary tumor (ρ 0.78-0.92; p<0.0001) apparent diffusion coefficient and plasma flow (PF) values was good to very good. PFTumor values decreased with cT stage with significant differences identified between cT2 and cT3 tumors (229 versus 107.6 ml/100ml/min; p=0.05). ADCTumor values did not differ significantly. No substantial discrepancies in lymph node ADCLn values or short axis diameter were found among cN1-3 stages, whereas PFLn values were distinct between cN1 versus cN2 stages (p=0.03). In the patients without neoadjuvant RCT no statistically significant differences in the assessed functional parameters on the basis of pathologic stage were found.

CONCLUSION

This study illustrates that ADC as well as MR perfusion values can be analyzed with good interobserver agreement in patients with rectal cancer. Moreover, MR perfusion parameters may allow accurate differentiation of tumor stages. Both findings suggest that functional MRI parameters may help to discriminate T and N stages for clinical decision making.

Role of Perfusion CT Differentiating Hemangiomas from Malignant Hepatic Lesions

Objective:

The purpose of the study was to determine the role of computed tomography (CT) perfusion in differentiating hemangiomas from malignant hepatic lesions.

Materials and Methods:

This study was approved by the institutional review board. All the patients provided informed consent. CT perfusion was performed with 64 multidetector CT (MDCT) scanner on 45 patients including 27 cases of metastasis, 9 cases of hepatocellular carcinoma (HCC), and 9 cases of hemangiomas. A 14 cm span of the liver was covered during the perfusion study. Data was analyzed to calculate blood flow (BF), blood volume (BV), permeability surface area product (PS), mean transit time (MTT), hepatic arterial fraction (HAF), and induced residue fraction time of onset (IRFTO). CT perfusion parameters at the periphery of lesions and background liver parenchyma were compared.

Results:

Significant changes were observed in the perfusion parameters at the periphery of different lesions. Of all the perfusion parameters BF, HAF, and IRFTO showed most significant changes. In our study we found: BF of more than 400 ml/100 g/min at the periphery of the hemangiomas showed sensitivity of 88.9%, specificity of 83.3%, positive predictive value (PPV) of 57.1%, and negative predictive value (NPV) of 96.7% in differentiating hemangiomas from hepatic malignancy; HAF of more than 60% at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3% and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy; IRFTO of more than 3 s at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3%, and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy.

Conclusion:

Perfusion CT is a helpful tool in differentiating hemangiomas from hepatic malignancy by its ability to determine changes in perfusion parameters of the lesions.

Heterogeneity of tumor vasculature and antiangiogenic intervention: insights from MR angiography and DCE-MRI

PURPOSE

Solid tumor vasculature is highly heterogeneous, which presents challenges to antiangiogenic intervention as well as the evaluation of its therapeutic efficacy. The aim of this study is to evaluate the spatial tumor vascular changes due to bevacizumab/paclitaxel therapy using a combination approach of MR angiography and DCE-MRI method.

EXPERIMENTAL DESIGN

Tumor vasculature of MCF-7 breast tumor mouse xenografts was studied by a combination of MR angiography and DCE-MRI with albumin-Gd-DTPA. Tumor macroscopic vasculature was extracted from the early enhanced images. Tumor microvascular parameters were obtained from the pharmacokinetic modeling of the DCE-MRI data. A spatial analysis of the microvascular parameters based on the macroscopic vasculature was used to evaluate the changes of the heterogeneous vasculature induced by a 12 day bevacizumab/paclitaxel treatment in mice bearing MCF-7 breast tumor.

RESULTS

Macroscopic vessels that feed the tumors were not affected by the bevacizumab/paclitaxel combination therapy. A higher portion of the tumors was within close proximity of these macroscopic vessels after the treatment, concomitant with tumor growth retardation. There was a significant decrease in microvascular permeability and vascular volume in the tumor regions near these vessels.

CONCLUSION

Bevacizumab/paclitaxel combination therapy did not block the blood supply to the MCF-7 breast tumor. Such finding is consistent with the modest survival benefits of adding bevacizumab to current treatment regimens for some types of cancers.

Functional imaging biomarkers for assessing response to treatment in liver and lung metastases

Management of patients with metastatic cancer and development of new treatments rely on imaging to provide non-invasive biomarkers of tumour response and progression. The widely used size-based criteria have increasingly become inadequate where early measures of response are required to avoid toxicity of ineffective treatments, as biological, physiologic, and molecular modifications in tumours occur before changes in gross tumour size. A multiparametric approach with the current range of imaging techniques allows functional aspects of tumours to be simultaneously interrogated. Appropriate use of these imaging techniques and their timing in relation to the treatment schedule, particularly in the context of clinical trials, is fundamental. There is a lack of consensus regarding which imaging parameters are most informative for a particular disease site and the best time to image so that, despite an increasing body of literature, open questions on these aspects remain. In addition, standardization of these new parameters is required. This review summarizes the published literature over the last decade on functional and molecular imaging techniques in assessing treatment response in liver and lung metastases.

CT assessment of liver hemodynamics in patients with hepatocellular carcinoma after argon-helium cryoablation

BACKGROUND

Assessment of tumor response after argon-helium cryoablation is critical in guiding future therapy for unresectable hepatocellular carcinoma. This study aimed to evaluate liver hemodynamics in hepatocellular carcinoma after argon-helium cryoablation with computed tomography perfusion.

METHODS

The control group comprised 40 volunteers without liver disease. The experimental group was composed of 15 patients with hepatocellular carcinoma treated with argon-helium cryoablation. Computed tomography perfusion parameters were measured: hepatic blood flow, hepatic blood volume, mean transit time, permeability of capillary vessel surface, hepatic arterial fraction, hepatic arterial perfusion, and hepatic portal perfusion.

RESULTS

After treatment, in the tumor foci, permeability of capillary vessel surface was higher, and hepatic blood flow, hepatic blood volume, hepatic arterial fraction, and hepatic arterial perfusion values were lower (P<0.05). In the liver parenchyma surrounding the tumor, hepatic arterial perfusion was significantly lower (P<0.05); however, there was no significant difference in hepatic blood flow, hepatic blood volume, mean transit time, permeability of capillary vessel surface, hepatic arterial fraction, or hepatic portal perfusion (P>0.05).

CONCLUSION

Computed tomography perfusion can evaluate tumor response after argon-helium cryoablation.

Assessment of blood flow in hepatocellular carcinoma: correlations of computed tomography perfusion imaging and circulating angiogenic factors

Hepatocellular carcinoma (HCC) is a highly vascular tumor through the process of angiogenesis. To evaluate more non-invasive techniques for assessment of blood flow (BF) in HCC, this study examined the relationships between BF of HCC measured by computer tomography (CT) perfusion imaging and four circulating angiogenic factors in HCC patients. Interleukin 6 (IL-6), interleukin 8 (IL-8), vascular endothelial growth factor (VEGF), and platelet derived growth factor (PDGF) in plasma were measured using Bio-Plex multiplex immunoassay in 21 HCC patients and eight healthy controls. Circulating IL-6, IL-8 and VEGF showed higher concentrations in HCC patients than in controls (p < 0.05), and predicted HCC occurrence better than chance (p < 0.01). Twenty-one patients with HCC received 21-phase liver imaging using a 64-slice CT. Total BF, arterial BF, portal BF, arterial fraction (arterial BF/total BF) of the HCC and surrounding liver parenchyma, and HCC-parenchyma ratio were measured using a dual-vessel model. After analyzing the correlations between BF in HCC and four circulating angiogenic factors, we found that the HCC-parenchyma ratio of arterial BF showed a significantly positive correlation with the level of circulating IL-8 (p < 0.05). This circulating biomarker, IL-8, provides a non-invasive tool for assessment of BF in HCC.

Characterising neovascularisation in fracture healing with laser Doppler and micro-CT scanning

Vascularity of the soft tissues around a bone fracture is critical for successful healing, particularly when the vessels in the medullary canal are ruptured. The objective of this work was to use laser Doppler and micro-computer tomography (micro-CT) scanning to characterise neovascularisation of the soft tissues surrounding the fracture during healing. Thirty-two Sprague–Dawley rats underwent mid-shaft osteotomy of the left femur, stabilised with a custom-designed external fixator. Five animals were killed at each of 2, 4 days, 1, 2, 4 and 6 weeks post-operatively. Femoral blood perfusion in the fractured and intact contralateral limbs was measured using laser Doppler scanning pre- and post-operatively and throughout the healing period. At sacrifice, the common iliac artery was cannulated and infused with silicone contrast agent. Micro-CT scans of the femur and adjacent soft tissues revealed vessel characteristics and distribution in relation to the fracture zone. Blood perfusion dropped immediately after surgery and then recovered to greater than the pre-operative level by proliferation of small vessels around the fracture zone. Multi-modal imaging allowed both longitudinal functional and detailed structural analysis of the neovascularisation process.

Assessment of hemodynamics in a rat model of liver cirrhosis with precancerous lesions using multislice spiral CT perfusion imaging

Rationale and Objectives. To develop an optimal scanning protocol for multislice spiral CT perfusion (CTP) imaging to evaluate hemodynamic changes in liver cirrhosis with diethylnitrosamine- (DEN-) induced precancerous lesions. Materials and Methods. Male Wistar rats were randomly divided into the control group (n = 80) and the precancerous liver cirrhosis group (n = 40). The control group received saline injection and the liver cirrhosis group received 50 mg/kg DEN i.p. twice a week for 12 weeks. All animals underwent plain CT scanning, CTP, and contrast-enhanced CT scanning. Scanning parameters were optimized by adjusting the diatrizoate concentration, the flow rate, and the delivery time. The hemodynamics of both groups was further compared using optimized multislice spiral CTP imaging. Results. High-quality CTP images were obtained with following parameters: 150 kV; 150 mAs; 5 mm thickness, 5 mm interval; pitch, 1; matrix, 512 × 512; and FOV, 9.6 cm. Compared to the control group, the liver cirrhosis group had a significantly increased value of the hepatic arterial fraction and the hepatic artery perfusion (P < 0.05) but significantly decreased hepatic portal perfusion and mean transit time (P < 0.05). Conclusion. Multislice spiral CTP imaging can be used to evaluate the hemodynamic changes in the rat model of liver cirrhosis with precancerous lesions.

Molecular MR imaging of neovascular progression in the Vx2 tumor with αvβ3-targeted paramagnetic nanoparticles

PURPOSE

To assess the dependence of neovascular molecular magnetic resonance (MR) imaging on relaxivity (r1) of αvβ3-targeted paramagnetic perfluorocarbon (PFC) nanoparticles and to delineate the temporal-spatial consistency of angiogenesis assessments for individual animals.

MATERIALS AND METHODS

Animal protocols were approved by the Washington University Animal Studies Committee. Proton longitudinal and transverse relaxation rates of αvβ3-targeted and nontargeted PFC nanoparticles incorporating gadolinium diethylenetrianime pentaacedic acid (Gd-DTPA) bisoleate (BOA) or gadolinium tetraazacyclododecane tetraacetic acid (Gd-DOTA) phosphatidylethanolamine (PE) into the surfactant were measured at 3.0 T. These paramagnetic nanoparticles were compared in 30 New Zealand White rabbits (four to six rabbits per group) 14 days after implantation of a Vx2 tumor. Subsequently, serial MR (3.0 T) neovascular maps were developed 8, 14, and 16 days after tumor implantation by using αvβ3-targeted Gd-DOTA-PE nanoparticles (n = 4) or nontargeted Gd-DOTA-PE nanoparticles (n = 4). Data were analyzed with analysis of variance and nonparametric statistics.

RESULTS

At 3.0 T, Gd-DTPA-BOA nanoparticles had an ionic r1 of 10.3 L · mmol(-1) · sec(-1) and a particulate r1 of 927000 L · mmol(-1) · sec(-1). Gd-DOTA-PE nanoparticles had an ionic r1 of 13.3 L · mmol(-1) · sec(-1) and a particulate r1 of 1 197000 L · mmol(-1) · sec(-1). Neovascular contrast enhancement in Vx2 tumors (at 14 days) was 5.4% ± 1.06 of the surface volume with αvβ3-targeted Gd-DOTA-PE nanoparticles and 3.0% ± 0.3 with αvβ3-targeted Gd-DTPA-BOA nanoparticles (P = .03). MR neovascular contrast maps of tumors 8, 14, and 16 days after implantation revealed temporally consistent and progressive surface enhancement (1.0% ± 0.3, 4.5% ± 0.9, and 9.3% ± 1.4, respectively; P = .0008), with similar time-dependent changes observed among individual animals.

CONCLUSION

Temporal-spatial patterns of angiogenesis for individual animals were followed to monitor longitudinal tumor progression. Neovasculature enhancement was dependent on the relaxivity of the targeted agent.

Viable residual tumor tissue after radiofrequency ablation treatment in hepatocellular carcinoma: evaluation with CT perfusion

PURPOSE

To assess the role of CT perfusion technique in detection of blood flow changes related to the therapeutic effects in HCC lesion treated with RFA.

METHODS

14 cirrhotic patients with known HCC underwent a perfusion study about 4 months (range 1-13 months) after RFA on a 16-slice MDCT scanner (Brilliance, Philips). Dynamic CT was performed acquiring 8 dynamic slice/scan, after injection of 50 mL of contrast media. In treated lesion, surrounding parenchyma and hypervascular tissue suspicious for residual disease/recurrence, the following perfusion parameters were analyzed: perfusion (P, mL/100 g min); arterial perfusion (AP, mL/min); blood volume (BV, mL/100 mg); hepatic perfusion index (HPI, %), and time to peak (TTP, s). Univariate Wilcoxon signed rank test was used for statistical analysis.

RESULTS

In patients with residual disease (8/14) values of perfusion parameters measured within tumor were: P, median = 45.2; AP, median = 48.2; BV, median = 18.9; HPI, median = 35.8; and TTP, median = 19.4. The values calculated in ablated area were: P, median = 10.9; AP, median = 9.6; BV, median = 5.5; HPI, median = 14.6; TTP, median = 39.6. The parameters calculated in the surrounding parenchyma were: P, median = 15.8; AP, median = 14.2; BV, median = 12.0; HPI, median = 17.9; TTP, median = 43.2. A significant difference (P < 0.05) was observed in mean values of P, AP, and HPI, calculated between treated lesions with residual tumor and those successfully treated.

CONCLUSION

Perfusion CT enables assessment of HCC vascularity after RFA treatment, by adding quantitative information about the presence of residual arterial vessels within the viable residual neoplastic tissue.

Response evaluation in patients with colorectal liver metastases: RECIST version 1.1 versus modified CT criteria

OBJECTIVE

Our retrospective study compared Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 with modified CT criteria to determine their respective utilities as a prognostic indicator. Using both sets of criteria, we compared treatment responses of patients with colorectal liver metastases treated with bevacizumab-containing chemotherapy with those of patients treated with chemotherapy alone.

MATERIALS AND METHODS

Fifty-nine patients who received bevacizumab-containing chemotherapy (n=30, group 1) or chemotherapy alone (n=29, group 2) for the treatment of colorectal carcinoma underwent contrast-enhanced CT before treatment and 2 months after treatment. Two radiologists determined changes in tumor size and density between the pretreatment and 2-month follow-up CT images. RECIST 1.1 assesses responses on the basis of changes in tumor size, and the modified CT criteria assesses responses on the basis of changes in tumor density and size. Responses were correlated with time to tumor progression by log rank test.

RESULTS

According to RECIST 1.1, nine of 30 patients (30%) in group 1 and 12 of 29 patients (41%) in group 2 were good responders. According to the modified CT criteria, 23 of 30 patients in group 1 (77%) and 23 of 29 patients in group 2 (79%) were good responders. As assessed by the modified CT criteria, good responders in both groups had significantly longer time to tumor progression than poor responders (p<0.05). As assessed by RECIST 1.1, good responders in group 1 had significantly longer time to tumor progression than poor responders (p=0.0154), but there was no difference in group 2.

CONCLUSION

Evaluating treatment response with tumor size and density changes on CT was a better predictor of time to tumor progression than changes in tumor size alone in both groups.

Evaluation of changes in the tumor microenvironment after sorafenib therapy by sequential histology and 18F-fluoromisonidazole hypoxia imaging in renal cell carcinoma

The mechanistic dissociation of ‘tumor starvation’ versus ‘vascular normalization’ following anti-angiogenic therapy is a subject of intense controversy in the field of experimental research. In addition, accurately evaluating changes of the tumor microenvironment after anti-angiogenic therapy is important for optimizing treatment strategy. Sorafenib has considerable anti-angiogenic effects that lead to tumor starvation and induce tumor hypoxia in the highly vascularized renal cell carcinoma (RCC) xenografts. ¹⁸F-fluoromisonidazole (¹⁸F-FMISO) is a proven hypoxia imaging probe. Thus, to clarify early changes in the tumor microenvironment following anti-angiogenic therapy and whether ¹⁸F-FMISO imaging can detect those changes, we evaluated early changes in the tumor microenvironment after sorafenib treatment in an RCC xenograft by sequential histological analysis and ¹⁸F-FMISO autoradiography (ARG). A human RCC xenograft (A498) was established in nude mice, for histological studies and ARG, and further assigned to the control and sorafenib-treated groups (80 mg/kg, per os). Mice were sacrificed on Days 1, 2, 3 and 7 in the histological study, and on Days 3 and 7 in ARG after sorafenib treatment. Tumor volume was measured every day. ¹⁸F-FMISO and pimonidazole were injected intravenously 4 and 2 h before sacrifice, respectively. Tumor sections were stained with hematoxylin and eosin and immunohistochemically with pimonidazole and CD31. Intratumoral ¹⁸F-FMISO distribution was quantified in ARG. Tumor volume did not significantly change on Day 7 after sorafenib treatment. In the histological study, hypoxic fraction significantly increased on Day 2, mean vessel density significantly decreased on Day 1 and necrosis area significantly increased on Day 2 after sorafenib treatment. Intratumoral ¹⁸F-FMISO distribution significantly increased on Days 3 (10.2-fold, p<0.01) and 7 (4.1-fold, p<0.01) after sorafenib treatment. The sequential histological evaluation of the tumor microenvironment clarified tumor starvation in A498 xenografts treated with sorafenib. ¹⁸F-FMISO hypoxia imaging confirmed the tumor starvation. ¹⁸F-FMISO PET may contribute to determine an optimum treatment protocol after anti-angiogenic therapy.

Grading of uterine cervical cancer by using the ADC difference value and its correlation with microvascular density and vascular endothelial growth factor

OBJECTIVE

To investigate the application value of the ADC(difference) value in evaluating the pathological grade of uterine cervical cancer and to analyse the correlations among microvascular density (MVD), vascular endothelial growth factor (VEGF) expression and maximum ADC(difference) value.

METHODS

Fifty-six patients with uterine cervical cancer were included in this prospective study. All underwent conventional MRI and DWI. MVD and VEGF were evaluated by immunohistochemical staining with anti-CD34 and anti-VEGF, respectively.

RESULTS

Maximum ADC(difference) value and MVD count showed statistical differences among different pathological grades (P < 0.001, P < 0.001). There was a significant positive linear correlation between the maximum ADC(difference) value and pathological tumour grade (P < 0.001), and also between MVD count and pathological tumour grade (P < 0.001). No significant differences were found between the level of VEGF expression and pathological tumour grade (P = 0.222). The maximum ADC(difference) value correlated positively with both the MVD count and the level of VEGF expression (P < 0.001, P < 0.001).

CONCLUSIONS

Quantitative analysis of maximum ADC(difference) value of uterine cervical cancer may represent the grade of tumour differentiation and provide valuable information on tumour microcirculation and perfusion, thus allowing a promising new method of non-invasively assessing the pathological grade, which could serve as a substitution for assessing tumour angiogenesis.

Early changes of hepatic hemodynamics measured by functional CT perfusion in a rabbit model of liver tumor

BACKGROUND

Early detection and treatment of hepatocellular carcinoma is crucial to improving the patients' survival. The hemodynamic changes caused by tumors can be serially measured using CT perfusion. In this study, we used a CT perfusion technique to demonstrate the changes of hepatic hemodynamics in early tumor growth, as a proof-of-concept study for human early hepatocellular carcinoma.

METHODS

VX2 tumors were implanted in the liver of ten New Zealand rabbits. CT perfusion scans were made 1 week (early) and 2 weeks (late) after tumor implantation. Ten normal rabbits served as controls. CT perfusion parameters were obtained at the tumor rim, normal tissue surrounding the tumor, and control liver; the parameters were hepatic blood flow, hepatic blood volume, mean transit time, permeability of capillary vessel surface, hepatic arterial index, hepatic arterial perfusion and hepatic portal perfusion. Microvessel density and vascular endothelial growth factor were correlated.

RESULTS

At the tumor rim, compared to the controls, hepatic blood flow, hepatic blood volume, permeability of capillary vessel surface, hepatic arterial index, and hepatic arterial perfusion increased, while mean transit time and hepatic portal perfusion decreased on both early and late scans (P<0.05). Hepatic arterial index increased (135%, P<0.05), combined with a sharp increase in hepatic arterial perfusion (182%, P<0.05) and a marked decrease in hepatic portal perfusion (-76%, P<0.05) at 2 weeks rather than at 1 week (P<0.05). Microvessel density and vascular endothelial growth factor showed significant linear correlations with hepatic blood flow, permeability of capillary vessel surface and hepatic arterial index, but not with hepatic blood volume or mean transit time.

CONCLUSION

The CT perfusion technique demonstrated early changes of hepatic hemodynamics in this tumor model as proof-of-concept for early hepatocellular carcinoma detection in humans.

Differentiation between malignant and benign solitary pulmonary nodules: use of volume first-pass perfusion and combined with routine computed tomography

PURPOSE

To evaluate the capability of first-pass volume perfusion computed tomography (PCT) for differentiation of solitary pulmonary nodules (SPNs) and to compare that of combination of PCT and routine CT with CT alone for the differentiation.

MATERIALS AND METHODS

Our institutional review board approved this study and informed consent was obtained. With nine excluded, 65 consecutive patients having a SPN with histopathologic proof or follow-up underwent a 30s PCT using the deconvolution model were evaluated. Kruskal-Wallis tests and receiver operating characteristics (ROC) analysis were underwent. Four radiologists assessed nodules independently and retrospectively. Diagnostic capability was compared for CT alone and PCT plus CT. ROC analysis, McNemar test, and weighted kappa statistics were performed.

RESULTS

Significant differences were found in parameters between malignant and benign nodules (p<0.0001 for blood flow, blood volume, and permeability surface area product), SPNs were more likely to be malignant by using threshold values of more than 55 ml/100 g/min, 2.5 ml/100 g, and 10 ml/100 g/min, respectively. PCT plus CT was significantly better in overall sensitivity (93%, p=0.004) and accuracy (94%, p=0.003) compared to CT alone, not specificity (96%). Area under the curve for ROC analyses of PCT plus CT was significantly larger than that of CT alone (p=0.018). Mean weighted kappa for PCT plus CT was 0.715, that for CT alone was 0.447.

CONCLUSION

Volume first-pass PCT can distinguish SPNs. Using PCT plus routine CT may be more sensitive and accurate for differentiating malignant from benign nodules than CT alone and allows more confidence and constancy.

Monitoring response to antiangiogenic treatment and predicting outcomes in advanced hepatocellular carcinoma using image biomarkers, CT perfusion, tumor density, and tumor size (RECIST)

PURPOSE

Our aim was to investigate the hypothesis that the CT perfusion (CTP) is a more sensitive image biomarker when compared with tumor burden (Response Evaluation Criteria in Solid Tumors [RECIST]) and tumor density (HU) for monitoring treatment changes and for predicting long-term outcome in advanced hepatocellular carcinoma (HCC) treated with a combination of antiangiogenic treatment and chemotherapy.

MATERIAL AND METHODS

In this phase II clinical trial, 33 patients with advanced HCC were enrolled and 23 were included in the current study. A diagnostic dual-phase contrast-enhanced CT and perfusion CT was performed at baseline and days 10 to 12 after initiation of antiangiogenic treatment (Bevacizumab). The patients subsequently received bevacizumab in combination with gemcitabine and oxaliplatin (GEMOX-B) and contrast-enhanced CT was performed at the end of treatment (after completing 3 cycles of GEMOX-B chemotherapy) and after every 8 week until there was evidence of disease progression or intolerable toxicity. The CTP protocol included a targeted dynamic cine acquisition for 25 to 30 seconds after 50 to 70 mL of iodinated contrast media injection at 5 to 7 mL/s. The CTP parameters were compared with tumor size (according to Response Evaluation Criteria in Solid Tumors, RECIST 1.1) and density measurements (HU) before and after treatment and correlated with patient's outcome in groups with and without tumor thrombus. A one-sided P value was calculated and the Bonferroni correction was used to address the issue of multiple comparisons.

RESULTS

On days 10 to 12 after initiation of bevacizumab, significant decrease in CTP parameters was noted (P < 0.005). There was a mild reduction in mean tumor density (P = 0.016) without any significant change in mean tumor size. Tumors with higher baseline mean transit time values on CTP correlated with favorable clinical outcome (partial response and stable disease) and had better 6 months progression-free survival (P = 0.002 and P = 0.005, respectively). The baseline transfer constant (Ktrans) of responders (1425.19 ± 609.47 mL/1000 mL/min) was significantly higher than that of nonresponders (935.96 ± 189.47 mL/1000 mL/min). The tumor thrombus in the portal vein demonstrated baseline perfusion values and post-treatment change values similar to the HCC.

CONCLUSION

In advanced HCC, CTP is a more sensitive image biomarker for monitoring early antiangiogenic treatment effects as well as in predicting outcome at the end of treatment and progression-free survival as compared with RECIST and tumor density.

Antiangiogenic and radiation therapy: early effects on in vivo computed tomography perfusion parameters in human colon cancer xenografts in mice

OBJECTIVES

To assess early treatment effects on computed tomography (CT) perfusion parameters after antiangiogenic and radiation therapy in subcutaneously implanted, human colon cancer xenografts in mice and to correlate in vivo CT perfusion parameters with ex vivo assays of tumor vascularity and hypoxia.

MATERIALS AND METHODS

Dynamic contrast-enhanced CT (perfusion CT, 129 mAs, 80 kV, 12 slices × 2.4 mm; 150 μL iodinated contrast agent injected at a rate of 1 mL/min intravenously) was performed in 100 subcutaneous human colon cancer xenografts on baseline day 0. Mice in group 1 (n=32) received a single dose of the antiangiogenic agent bevacizumab (10 mg/kg body weight), mice in group 2 (n=32) underwent a single radiation treatment (12 Gy), and mice in group 3 (n=32) remained untreated. On days 1, 3, 5, and 7 after treatment, 8 mice from each group underwent a second CT perfusion scan, respectively, after which tumors were excised for ex vivo analysis. Four mice were killed after baseline scanning on day 0 for ex vivo analysis. Blood flow (BF), blood volume (BV), and flow extraction product were calculated using the left ventricle as an arterial input function. Correlation of in vivo CT perfusion parameters with ex vivo microvessel density and extent of tumor hypoxia were assessed by immunofluorescence. Reproducibility of CT perfusion parameter measurements was calculated in an additional 8 tumor-bearing mice scanned twice within 5 hours with the same CT perfusion imaging protocol.

RESULTS

The intraclass correlation coefficients for BF, BV, and flow extraction product from repeated CT perfusion scans were 0.93 (95% confidence interval: 0.78, 0.97), 0.88 (0.66, 0.95), and 0.88 (0.56, 0.95), respectively. Changes in perfusion parameters and tumor volumes over time were different between treatments. After bevacizumab treatment, all 3 perfusion parameters significantly decreased from day 1 (P ≤ 0.006) and remained significantly decreased until day 7 (P ≤ 0.008); tumor volume increased significantly only on day 7 (P=0.04). After radiation treatment, all 3 perfusion parameters decreased significantly on day 1 (P < 0.001); BF and flow extraction product increased again on day 3 and 5, although without reaching statistically significant difference; and tumor volumes did not change significantly at all time points (P ≥ 0.3). In the control group, all 3 perfusion parameters did not change significantly, whereas tumor volume increased significantly at all the time points, compared with baseline (P ≤ 0.04). Ex vivo immunofluorescent staining showed good correlation between all 3 perfusion parameters and microvessel density (ρ=0.71, 0.66, and 0.69 for BF, BV, and flow extraction product, respectively; P < 0.001). There was a trend toward negative correlation between extent of hypoxia and all 3 perfusion parameters (ρ=-0.53, -0.47, and -0.40 for BF, BV, and flow extraction product, respectively; P ≥ 0.05).

CONCLUSIONS

CT perfusion allows a reproducible, noninvasive assessment of tumor vascularity in human colon cancer xenografts in mice. After antiangiogenic and radiation therapy, BF, BV, and flow extraction product significantly decrease and change faster than the tumor volume.

Quantitative assessment of tumour associated neovascularisation in patients with liver cirrhosis and hepatocellular carcinoma: role of dynamic-CT perfusion imaging

OBJECTIVE

To determine the value of perfusion computed tomography (CT-p) in the quantitative assessment of tumour-related neoangiogenesis processes in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Fifty-two biopsy proven HCC lesions were examined with dynamic CT investigations during injection of 50 mL of contrast agent (350 mgI/mL). A dedicated perfusion software which generated a quantitative map of arterial and portal perfusion by means of a colour scale was employed. The following parameters related to the blood microcirculation and tissue perfusion were calculated: hepatic perfusion (Perf), tissue blood volume (BV), hepatic perfusion index (HPI), arterial perfusion (AP), portal perfusion (PP), and time to peak (TTP). Perfusion parameters were statistically analysed, comparing neoplastic lesions with cirrhotic parenchyma.

RESULTS

Perf, BV, HPI and AP values were higher (P < 0.001), whereas PP and TTP were lower (P < 0.001) in HCC relative to the surrounding liver. No significant correlation was found between perfusion parameters and HCC grade. Values of perfusion parameters in the cirrhotic liver of patients with and without HCC were not significantly different.

CONCLUSIONS

Our results suggest that CT-p can help in non-invasive quantification of tumour blood supply, related to the formation of new arterial structures (neoangiogenesis), which are essential for tumour growth.

KEY POINTS

Perfusion computed tomography (CT) enables depiction of tumour vascular physiology. Perfusion CT is non-invasive and is now quick to perform and analyse. Quantitative measurements of hepatic perfusion provide important information about hepatocellular carcinoma (HCC). Such perfusion CT data may help in the determination of the outcome of HCC. Perfusion CT can act as an in-vivo biomarker of tumour-related angiogenesis.

Monitoring the longitudinal intra-tumor physiological impulse response to VEGFR2 blockade in breast tumors using DCE-CT

PURPOSE

The purpose of this study was to quantify and model the longitudinal intra-tumor physiological response to a single dose of a monoclonal antibody specific to the VEGFR2 using dynamic contrast-enhanced CT.

MATERIAL AND METHODS

Dynamic contrast-enhanced CT imaging was performed on athymic nude mice bearing xenograft VEGF-transfected MCF-7 tumors (MCF7(VEGF)) to quantify intra-tumor physiology pre- and post-injection (days 2, 7, and 14) of a nonspecific (IgG1, controls) and specific (DC101, treated) monoclonal antibody targeting VEGFR2. Parametrical maps of tumor physiology-perfusion (F), permeability surface area (PS), fractional plasma (f(p)), and interstitial space (f (is))-were obtained at four time points over a 2-week period.

RESULTS

A temporal multistage recovery process whereby a decoupling of the fractional change in physiological parameters (f (p), F) was observed when comparing treated to control tumors: f (p) and perfusion decreased by a combined 27% (P < 0.01) and 65% (P < 0.01) on day 2, while only perfusion remained reduced by 46% (P < 0.01) on day 7. Intra-tumor heterogeneity defined by the change in variance of perfusion decreased on days 2 and 7; no change in the variance of f(p) was observed. Analysis based on a mathematical model linking perfusion and vascular morphology indicates that a decrease in f(p) and perfusion was consistent with a reduction in blood vessel radius, followed by an increase in the vascular radius and tortuosity resulting in the decoupling of f(p) and perfusion before returning to control levels.

CONCLUSION

Inhibiting VEGFR2 activity results in a temporal decoupling of physiological parameters, which can be explained by a combination of morphological changes influencing perfusion. Such a decoupling has the potential to significantly impact the delivery of pharmaceuticals and oxygen within solid tumors, critical factors in combined anti-angiogenic and radio- and chemotherapies.

CTA combined with CT perfusion for assessing the efficacy of anti-angiogenic therapy in rabbit VX2 tumors

RATIONALE AND OBJECTIVES

The aim of this study was to validate the feasibility of assessing the efficacy of antiangiogenic therapy on VX2 tumors using three-dimensional computed tomographic (CT) angiography (CTA) combined with CT perfusion.

MATERIALS AND METHODS

Forty rabbits with VX2 tumors were randomly assigned to four groups according to different doses of antiangiogenic drug, which were administered intraperitoneally daily for 14 days. In each group, 10 animals were scanned using three-dimensional CTA and CT perfusion on days 1 and 2 after the latest administration of the drug. Tumor masses were sectioned, stained by immunohistochemistry, and processed for correlation between CT imaging and histology.

RESULTS

The numbers of new tumor vessels from CTA were significantly different among the four groups (P < .001). As the dose of the drug increased, blood flow and blood volume on CT perfusion increased linearly, but the mean transit time and permeability surface-area product decreased linearly (P < .001). Immunohistochemical analyses showed that microvascular density decreased, while both luminal vascular number and mature vessel number increased linearly as the drug dose increased (P < .001). CT manifestations were correlated well with histologic findings (P < .05).

CONCLUSIONS

It is feasible to assess the efficacy of antiangiogenic therapy on VX2 tumors using three-dimensional CTA combined with CT perfusion. Three-dimensional CTA can display the morphologic changes of tumor vessels, while CT perfusion can predict the functional changes of tumor vessels after antiangiogenic therapy.

Usefulness of perfusion CT to assess response to neoadjuvant combined chemoradiotherapy in patients with locally advanced rectal cancer

RATIONALE AND OBJECTIVES

To prospectively evaluate perfusion computed tomography (CT) for assessment of changes in tumor vascularity after chemoradiation therapy (CRT) in locally advanced rectal cancer and to analyze the correlation between baseline perfusion parameters and tumor response.

MATERIALS AND METHODS

Twenty patients with rectal cancer underwent baseline perfusion CT before CRT, and in 11 an examination after CRT was also performed. For each tumor, blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability-surface area product (PS) were quantified. The Mann-Whitney U test compared baseline perfusion parameters of responders and nonresponders and pre- and post-CRT measurements were compared by the Wilcoxon signed-rank test (P < .05 statistically significant for both tests).

RESULTS

Baseline BF was significantly lower (P = .013) and MTT was significantly higher (P = .006) in responders. Both were able to discriminate responders from nonresponders with a sensitivity of 80% and 100% and a specificity of 73.3% and 86.7%, respectively, for BF and MTT. Baseline BV and PS were not significantly different in responders and nonresponders. Perfusion parameters changed significantly in post-CRT scans compared to baseline: BF (P = .003), BV (P = .003), and PS (P = .008) decreased, whereas MTT increased (P = .006).

CONCLUSION

Baseline BF and MTT can discriminate patients with a favorable response from those that fail to respond to CRT, potentially selecting high-risk patients with resistant tumors that may benefit from an aggressive preoperative treatment approach.

Dynamic contrast-enhanced micro-CT on mice with mammary carcinoma for the assessment of antiangiogenic therapy response

OBJECTIVE

To evaluate the potential of in vivo dynamic contrast-enhanced micro-computed tomography (DCE micro-CT) for the assessment of antiangiogenic drug therapy response of mice with mammary carcinoma.

METHODS

20 female mice with implanted MCF7 tumours were split into control group and therapy group treated with a known effective antiangiogenic drug. All mice underwent DCE micro-CT for the 3D analysis of functional parameters (relative blood volume [rBV], vascular permeability [K], area under the time-enhancement curve [AUC]) and morphology. All parameters were determined for total, peripheral and central tumour volumes of interest (VOIs). Immunohistochemistry was performed to characterise tumour vascularisation. 3D dose distributions were determined.

RESULTS

The mean AUCs were significantly lower in therapy with P values of 0.012, 0.007 and 0.023 for total, peripheral and central tumour VOIs. K and rBV showed significant differences for the peripheral (P(per)(K) = 0.032, P(per) (rBV) = 0.029), but not for the total and central tumour VOIs (P(total)(K) = 0.108, P(central)(K) = 0.246, P(total) (rBV) = 0.093, P(central) (rBV) = 0.136). Mean tumour volume was significantly smaller in therapy (P (in vivo) = 0.001, P (ex vivo) = 0.005). Histology revealed greater vascularisation in the controls and central tumour necrosis. Doses ranged from 150 to 300 mGy.

CONCLUSIONS

This study indicates the great potential of DCE micro-CT for early in vivo assessment of antiangiogenic drug therapy response.

KEY POINTS

Dynamic contrast enhanced micro-CT (computed tomography) is a new experimental laboratory technique. DCE micro-CT allows early in vivo assessment of antiangiogenic drug therapy response. Pharmaceutical drugs can be tested before translation to clinical practice. Both morphological and functional parameters can be obtained using DCE micro-CT. Antiangiogenic effects can be visualised with DCE micro-CT.

Perfusion CT evaluation in experimentally induced testicular torsion

INTRODUCTION

In this study, we define the characteristics of perfusion computed tomography (CT) in an experimental model of testicular torsion.

METHODS

Twenty male Sprague-Dawley rats were included for the study. Torsion was applied to 10 rats and perfusion CT was performed in the first hour to evaluate the following perfusion parameters: blood flow (BF), blood volume (BV) and time to peak (TTP) values. Detorsion was done for the same rats, and perfusion CT was repeated 2 hours later to evaluate reperfusion. Ten rats were left as part of the control group.

RESULTS

There is significant statistical correlation between the BF and BV values in the torsion and control groups (p = 0.001 and p = 0.001, respectively). There is no statistical correlation of the TTP parameters between the groups. No correlation was found between torsion and detorsion perfusion parameters.

CONCLUSION

Perfusion CT can demonstrate the testicular perfusion insult in an experimental model of torsion. Perfusion CT may be an alternative method for diagnosis of torsion in indeterminate cases. Following detorsion an interval of 2 hours is not sufficient for demonstrating luxury perfusion of the testis.

Combination therapy of transcatheter arterial chemoembolization and arterial administration of antiangiogenesis on VX2 liver tumor

PURPOSE

This study was designed to evaluate the antitumorigenic efficiency of Endostar (an antiangiogenic agent) arterially administrated combined with transcatheter arterial chemoembolization (TACE) on liver tumor, and validation of perfusion CT for quantitative measurements of the results.

EXPERIMENTAL DESIGN

Thirty rabbits bearing VX2 liver tumors were randomly and equally distributed into three groups. One of the following treatment protocols was performed in each group: 1) group 1 was treated with TACE and simultaneously arterially administrated Endostar; 2) group 2 with TACE alone, and 3) a control group that had saline injected through hepatic artery. Routine CT scan was performed before treatment, and perfusion CT imaging was performed 2 weeks after treatment. Immunohistochemical biomarkers of microvascular density (MVD) and the expression of vascular endothelial growth factor (VEGF) were measured for assessments of angiogenesis.

RESULTS

We observed a statistically significant reduction from the control in the volume, growth rate, and size of the tumor 2 weeks after treatment with both TACE plus Endostar and with TACE alone (P < 0.01). Although there was no statistically significant difference in tumor size between the group with TACE plus Endostar and the group with TACE alone (P > 0.05), MVD and VEGF were significantly less expressed in the TACE plus Endostar group than both groups with TACE alone and the control group (P < 0.01). Blood flow (BF), blood volume (BV), and permeability-surface area products (PS) in the group with TACE plus Endostar on perfusion CT were significantly higher than other two groups (P < 0.05), which were positively correlated with the MVD and VEGF values (P < 0.05).

CONCLUSIONS

TACE with arterial administration of Endostar simultaneously significantly inhibited the angiogenesis biomarkers associated with TACE in a rabbit model bearing VX2 liver tumor, which indicates that the combined treatment protocol may have potential synergistic effects on liver cancer. It also is suggested that perfusion CT may be useful for monitoring antiangiogenic/antivascular treatment in the liver tumors.