Role of CT perfusion in monitoring and prediction of response to therapy of head and neck squamous cell carcinoma

CECT and CT Perfusion Correlation with Pathological Differentiation of Pharyngeal and Laryngeal Cancers: Study from a Tertiary Care Center in Northeast India

Introduction  Pharyngeal and laryngeal carcinomas, included under head and neck cancers, pose a significant challenge in India, accounting for around one-third of all cancer cases. Noninvasive techniques like contrast-enhanced computed tomography (CECT) and CT perfusion (CTp) can help explore the correlation between tumor differentiations, which can greatly benefit in the diagnosis, understanding of recurrence postintervention, and monitoring of the progress of the disease. Materials and Methods  A hospital-based cross-sectional study was conducted for a duration of 18 months in a tertiary care center of northeast India with a sample of 40 patients. CECT and CTp were done and the variables were correlated with pathological differentiation of tumors. Results  The mean age of the study population was 54 years. No statistically significant associations were noted between the age, size, margins, location, and T-staging of tumors with the pathological differentiation of tumors. However, significant association was found between the CTp parameters, namely blood flow (BF), blood volume, mean transit time, time to drain, and time to peak with respect to the pathological differentiation of tumors ( p  < 0.05). Conclusion  The addition of CTp to conventional CT sequences in the evaluation of pharyngeal and laryngeal cancers offers significant benefits in understanding the tumor physiology and behavior.

Dual-energy CT perfusion imaging for differentiating invasive thymomas, thymic carcinomas, and lymphomas in adults

AIM

To evaluate the role of dual-energy computed tomography perfusion (DECTP) imaging in differentiating invasive thymomas (ITs), thymic cancers (TCs), and lymphomas in adults.

MATERIALS AND METHODS

Ninety-five patients with solid masses in the prevascular mediastinum who underwent DECTP examinations were enrolled in this study. The perfusion parameters (blood flow, BF; blood volume, BV; mean transit time, MTT; permeability surface, PS) and spectral parameters (water concentration, WC; iodine concentration, IC; normalised iodine concentration, NIC; the slope of spectral radiodensity [Hounsfield units] curve, λ_HU) of the lesions were analysed.

RESULTS

There were no differences in the MTT or WC values among ITs, TCs, and lymphomas (all p>0.05). The IC, NIC, and λ_HU values in the optimal arterial and venous phases and PS values of TCs were higher than those of ITs and lymphomas (all p<0.05), and there were no differences between ITs and lymphomas (all p>0.05). The BF and BV values of lymphomas were lower than those of ITs and TCs (all p<0.05), and there were no differences between ITs and TCs (all p>0.05). The cut-off values for BF and BV used to differentiate lymphomas from ITs and TCs were 42.83 ml/min/100 g and 4.66 ml/100 g, respectively (area under the receiver operating characteristic curve: 0.847 and 0.839; sensitivity, 80.6% and 82.1%; specificity, 75% and 71.4%; accuracy, 78.9% and 81.1%).

CONCLUSIONS

The perfusion and spectral parameters of DECTP imaging help to identify ITs, TCs, and lymphomas, and BF and BV values help to differentiate lymphomas from ITs and TCs.

Improving radiation physics, tumor visualisation, and treatment quantification in radiotherapy with spectral or dual-energy CT

Over the past decade, spectral or dual‐energy CT has gained relevancy, especially in oncological radiology. Nonetheless, its use in the radiotherapy (RT) clinic remains limited. This review article aims to give an overview of the current state of spectral CT and to explore opportunities for applications in RT.

In this article, three groups of benefits of spectral CT over conventional CT in RT are recognized. Firstly, spectral CT provides more information of physical properties of the body, which can improve dose calculation. Furthermore, it improves the visibility of tumors, for a wide variety of malignancies as well as organs‐at‐risk OARs, which could reduce treatment uncertainty. And finally, spectral CT provides quantitative physiological information, which can be used to personalize and quantify treatment.

Diagnostic performance of dynamic volume perfusion CT for differentiation of head and neck cancer from healthy tissue and post-therapeutic changes

BACKGROUND

Post-therapeutic tissue is bradytrophic and thus has low perfusion values in PCT. In contrast, malignant tissue is expected to show higher perfusion values as cancer growth partially depends on angiogenesis.

OBJECTIVES

This prospective study investigates perfusion computed tomography (PCT) for the post-therapeutic detection of cancer in the head and neck region.

METHODS

85 patients underwent PCT for 1) initial work-up of head and neck cancer (HNC; n=22) or 2) for follow-up (n=63). Regions of interest (ROIs) were placed in confirmed tumour, a corresponding location of benign tissue, and reference tissue. Perfusion was calculated using a single input maximum slope algorithm. Statistical analysis was performed with the Mann-Whitney U-test.

RESULTS

PCT allowed significant differentiation of malignant tissue from post-therapeutic tissue after treatment for HNC (p=0.018). Significance was even greater after normalization of perfusion values (p=0.007). PCT allowed highly significant differentiation of HNC from reference tissue (p<0.001).

CONCLUSIONS

PCT provides significantly distinct perfusion values for malignant and benign as well as post-therapeutically altered tissue in the head and neck area, thus allowing differentiation of cancer from healthy tissue. Our results show that PCT in conjunction with a standard algorithm is a potentially powerful HNC diagnostic tool.

The flow-metabolism ratio might predict treatment response and survival in patients with locally advanced esophageal squamous cell carcinoma

Background

Perfusion CT can offer functional information about tumor angiogenesis, and ¹⁸F-FDG PET/CT quantifies the glucose metabolic activity of tumors. This prospective study aims to investigate the value of biologically relevant imaging biomarkers for predicting treatment response and survival outcomes in patients with locally advanced esophageal squamous cell cancer (LA ESCC).

Methods

Twenty-seven patients with pathologically proven ESCC were included. All patients had undergone perfusion CT and ¹⁸F-FDG PET/CT using separate imaging systems before receiving definitive chemoradiotherapy (dCRT). The perfusion parameters included blood flow (BF), blood volume (BV), and time to peak (TTP), and the metabolic parameters included maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The flow-metabolism ratio (FMR) was defined as BF divided by SUVmax. Statistical methods used included Spearman’s rank correlation, Mann–Whitney U test or two-sample t test, receiver operating characteristic (ROC) curve analysis, the Kaplan–Meier method, and Cox proportional hazards models.

Results

The median overall survival (OS) and progression-free survival (PFS) were 18 and 11.6 months, respectively. FMR was significantly positively correlated with BF (r = 0.886, p < 0.001) and negatively correlated with SUVmax (r = − 0.547, p = 0.003) and TTP (r = − 0.462, p = 0.015) in the tumors. However, there was no significant correlation between perfusion and PET parameters. After dCRT, 14 patients (51.9%) were identified as responders, and another 13 were nonresponders. The BF and FMR of the responders were significantly higher than those of the nonresponders (42.05 ± 16.47 vs 27.48 ± 8.55, p = 0.007; 3.18 ± 1.15 vs 1.84 ± 0.65, p = 0.001). The ROC curves indicated that the FMR [area under the curve (AUC) = 0.846] was a better biomarker for predicting treatment response than BF (AUC = 0.802). Univariable Cox analysis revealed that of all imaging parameters, only the FMR was significantly correlated with overall survival (OS) (p = 0.015) and progression-free survival (PFS) (p = 0.017). Specifically, patients with a lower FMR had poorer survival. Multivariable analysis showed that after adjusting for age, clinical staging, and treatment response, the FMR remained an independent predictor of OS (p = 0.026) and PFS (p = 0.014).

Conclusions

The flow-metabolism mismatch demonstrated by a low FMR shows good potential in predicting chemoradiotherapy sensitivity and prognosis in ESCC.

Elastic scattering spectroscopy for monitoring skin cancer transformation and therapy in the near infrared window

There is a pressing need for monitoring cancerous tissue response to laser therapy. In this work, we evaluate the viability of elastic scattering spectroscopy (ESS) to monitor malignant transformations and effects of laser therapy of induced skin cancer in a hamster model. Skin tumors were induced in 35 mice, half of which were irradiated with 980 nm laser diode. Physiological and morphological transformations in the tumor were monitored over a period of 36 weeks using elastic scattering spectroscopy, in the near infrared window. Analytical model for light scattering was used to derive scattering optical properties for both transformed tissue and laser-treated cancer. The tissue scattering over the wavelength range (700-950 nm) decreased remarkably as the carcinogen-induced tissue transformed towards higher stages. Conversely, reduced scattering coefficient noticeably increased with increasing the number of laser irradiation sessions for the treated tumors. The relative changes in elastic scattering signal for transformed tissue were significantly different (p < .05). Elastic scattering signal intensity for laser-treated tissue was also significantly different (p < .05). Reduced scattering coefficient of treated tissue exhibited nearly 80% recovery of its normal skin value at the end of the experiment, and the treatment outcome could be improved by adjusting the number of sessions, which we can predict through spectroscopic optical feedback. This study demonstrates that ESS can quantitatively provide functional information that closely corresponds to the degree of pathologic transformation. ESS may well be a viable technique to optimize systemic melanoma and non-melanoma skin cancer treatment based on noninvasive tumor response.

Dual-energy CT perfusion imaging for differentiating WHO subtypes of thymic epithelial tumors

To evaluate the role of conventional contrast-enhanced CT (CECT) imaging and dual-energy spectral CT (DECT) perfusion imaging in differentiating the WHO histological subtypes of thymic epithelial tumours (TETs). Eighty-eight patients with TETs who underwent DECT perfusion scans (n = 51) and conventional CT enhancement scans (n = 37) using a GE Discovery CT750 HD scanner were enrolled in this study. The mean maximal contrast-enhanced range (mean CEmax) and the perfusion and spectral parameters of the lesions were analysed. Among the six WHO subtypes (Type A, AB, B1, B2, and B3 thymoma and thymic carcinoma), the mean CEmax values and most of the perfusion and spectral parameter values of Type A and Type AB were significantly higher than those of the other subtypes (all P < 0.05), and there was no difference among Type B1, B2 and B3 (all P > 0.05). The mean CEmax value was not different between Type B (including Type B1, B2, and B3) and thymic carcinoma (P = 1.000). The PS, IC, NIC and λHU values in the optimal venous phase of thymic carcinoma were higher than those of Type B (all P < 0.05). The parameters of conventional CECT imaging and DECT perfusion imaging can help identify the subtype of TETs, especially those of DECT perfusion imaging in type B thymomas and thymic carcinomas.

Multidetector Row Computed Tomography in Maxillofacial Imaging

Multidetector row CT (MDCT) offers superior soft tissue characterization and is useful for diagnosis of odontogenic and nonodontogenic cysts and tumors, fibro-osseous lesions, inflammatory, malignancy, metastatic lesions, developmental abnormalities, and maxillofacial trauma. The rapid advances in MDCT technology, including perfusion CT, dual-energy CT, and texture analysis, will be an integrated anatomic and functional high-resolution scan, which will help in diagnosis of maxillofacial lesions and overall patient care.

Combining Radiotherapy With Anti-angiogenic Therapy and Immunotherapy; A Therapeutic Triad for Cancer?

Radiotherapy has been used for the treatment of cancer for over a century. Throughout this period, the therapeutic benefit of radiotherapy has continuously progressed due to technical developments and increased insight in the biological mechanisms underlying the cellular responses to irradiation. In order to further improve radiotherapy efficacy, there is a mounting interest in combining radiotherapy with other forms of therapy such as anti-angiogenic therapy or immunotherapy. These strategies provide different opportunities and challenges, especially with regard to dose scheduling and timing. Addressing these issues requires insight in the interaction between the different treatment modalities. In the current review, we describe the basic principles of the effects of radiotherapy on tumor vascularization and tumor immunity and vice versa. We discuss the main strategies to combine these treatment modalities and the hurdles that have to be overcome in order to maximize therapeutic effectivity. Finally, we evaluate the outstanding questions and present future prospects of a therapeutic triad for cancer.

Stability of radiomic features in CT perfusion maps

This study aimed to identify a set of stable radiomic parameters in CT perfusion (CTP) maps with respect to CTP calculation factors and image discretization, as an input for future prognostic models for local tumor response to chemo-radiotherapy. Pre-treatment CTP images of eleven patients with oropharyngeal carcinoma and eleven patients with non-small cell lung cancer (NSCLC) were analyzed. 315 radiomic parameters were studied per perfusion map (blood volume, blood flow and mean transit time). Radiomics robustness was investigated regarding the potentially standardizable (image discretization method, Hounsfield unit (HU) threshold, voxel size and temporal resolution) and non-standardizable (artery contouring and noise threshold) perfusion calculation factors using the intraclass correlation (ICC). To gain added value for our model radiomic parameters correlated with tumor volume, a well-known predictive factor for local tumor response to chemo-radiotherapy, were excluded from the analysis. The remaining stable radiomic parameters were grouped according to inter-parameter Spearman correlations and for each group the parameter with the highest ICC was included in the final set. The acceptance level was 0.9 and 0.7 for the ICC and correlation, respectively. The image discretization method using fixed number of bins or fixed intervals gave a similar number of stable radiomic parameters (around 40%). The potentially standardizable factors introduced more variability into radiomic parameters than the non-standardizable ones with 56-98% and 43-58% instability rates, respectively. The highest variability was observed for voxel size (instability rate  >97% for both patient cohorts). Without standardization of CTP calculation factors none of the studied radiomic parameters were stable. After standardization with respect to non-standardizable factors ten radiomic parameters were stable for both patient cohorts after correction for inter-parameter correlations. Voxel size, image discretization, HU threshold and temporal resolution have to be standardized to build a reliable predictive model based on CTP radiomics analysis.

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.

Role of perfusion CT in the evaluation of functional primary tumour response after radiochemotherapy in head and neck cancer: preliminary findings

OBJECTIVE

To report the initial results of a prospective study aimed at evaluating the CT perfusion parameter changes (∆PCTp) of the primary tumour after radiochemotherapy (RCT) in head and neck cancer (HNC) and to correlate with positron emission tomography (PET)/CT response.

METHODS

Eligibility criteria included HNC (Stage III-IV) candidates for RCT. Patients underwent perfusion CT (PCT) at baseline and at 3 weeks and 3 months after treatment. Blood volume, blood flow, mean transit time (MTT) and permeability surface (PS) product were computed. Moreover, PET/CT was performed at baseline and 3 months after treatment. The ∆PCTp were evaluated between baseline and 3-week/3-month evaluations, whereas PET/CT response was based on the maximum standardized uptake value changes according to the European Organization for Research and Treatment of Cancer criteria.

RESULTS

Between July 2012 and July 2015, 25 patients were enrolled. A significant reduction of all CT tumour perfusion parameters (PCTp) was observed from the baseline to after RCT (p < 0.001). Specifically, a significant reduction was shown at 3 weeks for all PCTp except MTT (from 6.18 to 5.14 s; p = 0.722). Differently, a significant reduction of all PCTp (p < 0.001) including MTT (from 6.18 to 2.24 s; p = 0.001) was shown at 3 months. Moreover, the reduction of PS resulted in a significant prediction of PET/CT response at 3 months (p = 0.037) with the trend also at 3 weeks (p = 0.099) at the multivariate analysis.

CONCLUSION

Our preliminary findings seem to show that almost all PCTp are significantly reduced after RCT, whereas PS seems to come out as the strongest factor in predicting the PET/CT response.

ADVANCES IN KNOWLEDGE

This article provides information on the potential useful role of PCT in evaluating tumour response after both early and late RCT.

Combined PET/CT-perfusion in patients with head and neck cancers might predict failure after radio-chemotherapy: a proof of concept study

Background

[18F]FDG-PET/CT imaging is broadly used in head and neck cancer (HNSCC) patients. CT perfusion (CTP) is known to provide information about angiogenesis and blood-flow characteristics in tumors. The aim of this study was to evaluate the potential relationship of FDG-parameters and CTP-parameters in HNSCC preand post-therapy and the potential prognostic value of a combined PET/CT with CTP.

Methods

Thirteen patients with histologic proven HNSCC were prospectively included. All patients underwent a combined PET/CT with integrated CTP before and after therapy. Pre- and post-therapeutic data of CTP and PET of the tumors were compared. Differences were tested using Spearman’s rho test and Pearson’s correlation. A p-value of p <0.05 was considered statistically significant. Correlations were calculated using Pearson’s correlation. Bootstrap confidence intervals were calculated to test for additive confidence intervals.

Results

Three patients died due to malignancy recurrence, ten patients were free of recurrence until the end of the follow-up period. Patients with recurrent disease had significantly higher initial CTP-values compared to the recurrence-free patients: BFpre 267.4 (171.2)ml/100 mg/min, BVpre 40.9 (8.4)ml/100 mg and MTTpre 8.2 (6.1)sec. No higher SUVs initially but significantly higher TLG compared to patients without recurrence were found. Post-therapeutic PET-values differed significantly between the two groups: SUVmaxpost 6.0 (3.2), SUVmeanpost 3.6 (2.0) and TLG 21751.7 (29794.0).

Conclusion

In our proof of concept study, combined PET/CT with integrated CTP might show complementary prognostic data pre- and post chemo-radiotherapy. CTP may be used to predict local tumor recurrence, while FDGPET/CT is still needed for whole-body staging.

Technical prerequisites and imaging protocols for CT perfusion imaging in oncology

The aim of this review article is to define the technical prerequisites of modern state-of-the-art CT perfusion imaging in oncology at reasonable dose levels. The focus is mainly on abdominal and thoracic tumor imaging, as they pose the largest challenges with respect to attenuation and patient motion. We will show that low kV dynamic scanning in conjunction with detection technology optimized for low photon fluxes has the highest impact on reducing dose independently of other choices made in the protocol selection. We discuss, derived from relatively simple first principles, on what appropriate temporal sampling and total scan duration depend on and why optimized contrast medium injection protocols are also essential in limiting dose. Finally we will examine the possibility of simultaneously extracting standard morphological and functional information from one single 4D examination as a potential enabler for a more widespread use of dynamic contrast enhanced CT in oncology.

Validation of functional imaging as a biomarker for radiation treatment response

Major advances in radiotherapy techniques, increasing knowledge of tumour biology and the ability to translate these advances into new therapeutic approaches are important goals towards more individualized cancer treatment. With the development of non-invasive functional and molecular imaging techniques such as positron emission tomography (PET)-CT scanning and MRI, there is now a need to evaluate potential new biomarkers for tumour response prediction, for treatment individualization is not only based on morphological criteria but also on biological tumour characteristics. The goal of individualization of radiotherapy is to improve treatment outcome and potentially reduce chronic treatment toxicity. This review gives an overview of the molecular and functional imaging modalities of tumour hypoxia and tumour cell metabolism, proliferation and perfusion as predictive biomarkers for radiation treatment response in head and neck tumours and in lung tumours. The current status of knowledge on integration of PET/CT/MRI into treatment management and bioimage-guided adaptive radiotherapy are discussed.