Functional imaging in clinical oncology: magnetic resonance imaging- and computerised tomography-based techniques

Transarterial chemoembolization of colorectal cancer liver metastasis: improved tumor response by DSM-TACE versus conventional TACE, a prospective, randomized, single-center trial

OBJECTIVES

To prospectively evaluate the therapy response of third-line TACE with DSM or lipiodol in the treatment of CRLM using MRI.

METHODS

In this prospective, randomized, single-center trial, patients were randomly assigned to receive TACE therapy with either lipiodol or DSM as the embolization agent. Therapy response was evaluated using MRI. Local tumor response was determined according to RECIST 1.1, and survival data was analyzed using the Kaplan-Meier estimator.

RESULTS

Fifty patients (35 male, 15 female) were randomized and included in the survival analysis, whereas 31 patients completed therapy and were considered for evaluation of tumor responses (cTACE: n = 13, DSM-TACE: n = 18). In the cTACE group, PR was observed in 23%, SD in 15%, and PD in 62%. In the DSM-TACE-group, PR was observed in 22% of patients, SD in 56%, and PD in 22% (p = 0.047). In addition, the DSM-TACE group showed statistically significant tumor volume reduction (p = 0.006). Median apparent diffusion coefficient values were not significantly different between both groups at baseline (p = 0.26) and study endpoint (p = 0.83). Median survival in the cTACE group was 13 months (95% confidence interval, range 5-40 months) compared to 16 months (95% confidence interval, range 1-48 months) in the DSM-TACE group, exhibiting no statistically significant difference (p = 0.75).

CONCLUSION

DSM-TACE showed a significant difference reducing tumor volume and in tumor response according to RECIST 1.1 compared to cTACE. Thus, patients with CRLM might not only benefit from short embolization effect of DSM-TACE but also from better tumor responses. Apparent diffusion coefficients were not significantly different between both groups and cannot be used as a biomarker for monitoring for therapeutic effect of TACE.

KEY POINTS

• To our knowledge, this is the first prospective study that directly compared cTACE and DSM-TACE in patients with CRLM. • DSM-TACE showed a significant difference reducing tumor volume (p = 0.006) and in tumor response according to RECIST 1.1 (p = 0.047) compared to cTACE. • Survival analysis showed a median survival of 13 months in the cTACE group compared to 16 months in the DSM-TACE group (p = 0.75).

MRI assessment of hepatocellular carcinoma after locoregional therapy

Liver cirrhosis and hepatocellular carcinoma (HCC) constitute one of the major causes of morbidity, mortality, and high health care costs worldwide. Multiple treatment options are available for HCC depending on the clinical status of the patient, size and location of the tumor, and available techniques and expertise. Locoregional treatment options are multiple. The most challenging part is how to assess the treatment response by different imaging modalities, but our scope will be assessing the response to locoregional therapy for HCC by MRI. This will be addressed by conventional MR methods using LI-RADS v2018 and by functional MR using diffusion-weighted imaging, perfusion, and highlighting the value of the novel intravoxel incoherent motion (IVIM).

Effectiveness of FDG-PET/CT for evaluating early response to induction chemotherapy in head and neck squamous cell carcinoma: A systematic review

BACKGROUND

F-Fluoro-Deoxy-Glucose Positron Emission Tomography with Computed Tomography (F-FDG PET/CT) may be a powerful tool to predict treatment outcome. We aimed to review the effectiveness of F-FDG PET/CT in the assessment of early response to induction chemotherapy (IC) in patients with advanced Head and Neck Squamous Cell Cancer (HNSCC) without previous treatment.

METHODS

PubMed, Cochrane Library, Science Direct and Web of Science were searched to May 2016. Reference lists of the included articles and additional studies identified by one nuclear medicine expert were screened for potential relevant studies that investigated the effectiveness of F-FDG PET/CT performed before and after IC. Three authors independently screened all retrieved articles, selected studies that met inclusion criteria and extracted data. The methodology of the selected studies was evaluated by using the risk of bias checklist of the Agency for Healthcare Research and Quality (AHRQ).

RESULTS

Seven out of 170 eligible studies met our inclusion criteria. A total of 207 advanced HNSCC patients were evaluated with F-FDG PET/CT at baseline and after IC in the selected articles. Six from seven studies concluded that F-FDG PET/CT allowed early evaluation response to IC and predicted survival outcomes.

CONCLUSION

The present systematic review confirms the potential value of F-FDG PET/CT as a diagnostic tool for early IV response assessment in HNSCC patients. However, the lack of standard definitions for response criteria and heterogeneous IC protocols indicate the need to further studies in order to better define the role of F-FDG PET/CT in these patients.

Assessment of serial multi-parametric functional MRI (diffusion-weighted imaging and R2*) with (18)F-FDG-PET in patients with head and neck cancer treated with radiation therapy

OBJECTIVE

To evaluate the serial changes and correlations between readout-segmented technique with navigated phase correction diffusion-weighted MRI (DWI), R2*-MRI and (18)F-FDG positron emission tomography (PET) CT performed before and during radiation therapy (RT) in patients with mucosal primary head and neck cancer.

METHODS

The mean apparent diffusion coefficient (ADCmean) from DWI (at b = 50 and 800 s mm(-2)), the mean R2* values derived from T2(*)-MRI, and PET metabolic parameters, including maximum standardized uptake value (SUVmax), metabolic tumour volume (MTV) and total lesional glycolysis (TLG) were measured for the primary tumour. Spearman correlation coefficients were calculated to evaluate correlations between ADCmean, R2*, SUVmax, MTV and TLG. A paired t-test was performed to assess the MRI changes and the slope of serial MRI changes during RT.

RESULTS

Pre-treatment scans were performed in 28 patients and mid-treatment scans in 20 patients. No significant correlation was found between ADCmean and either R2* values or PET parameters. There were significant negative correlations of R2* values with pre-treatment PET parameters but not with mid-RT PET parameters: pre-SUVmax (p = 0.008), pre-MTV (p = 0.006) and pre-TLG (p = 0.008). A significant rise in ADCmean was found during the first half (p < 0.001) of RT but not in the second half (p = 0.215) of the treatment. There was an increase of the ADCmean values of 279.4 [95% confidence interval (95% CI): 210-348] in the first half of the treatment (Weeks 0-3). However, during the second-half period of treatment, the mean ADC value (Weeks 3-6) was 24.0 and the 95% CI (-40 to 88) included zero. This suggests that there was no significant change in ADC values during the second half of the treatment.

CONCLUSION

A significant negative correlation was found between pre-treatment R2*-MRI and PET parameters. DWI appeared to demonstrate potentially predictable changes during RT.

ADVANCES IN KNOWLEDGE

Understanding the correlation and changes that occur with time between potential imaging biomarkers may help us establish the most appropriate biomarkers to consider in future research.

Immediate post-doxorubicin drug-eluting beads chemoembolization Mr Apparent diffusion coefficient quantification predicts response in unresectable hepatocellular carcinoma: A pilot study

PURPOSE

To investigate magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) of hepatocellular carcinoma (HCC) immediately post-doxorubicin drug-eluting beads transcatheter arterial chemoembolization (DEB-TACE) therapy as an early imaging biomarker of therapy response.

MATERIALS AND METHODS

In a single-center prospective correlative study, 12 consecutive patients, median age 64 years, underwent DEB-TACE and dynamic contrast-enhanced (DCE) and DWI (b = 50,400,800 s/mm(2)) MRI at baseline with respect to first DEB-TACE, within 3 hours, and at 1 and 3 months posttherapy. DCE imaging response was evaluated according to target mRECIST and EASL. Relative change (RC) in apparent diffusion coefficient (ADC) of treated lesions was measured on follow-ups. Correlation between ADC RC in tumors and anatomical response were evaluated with paired t-test and receiver operator characteristic (ROC) curve. Survival from first DEB-TACE was estimated using Kaplan-Meier and log-rank analysis.

RESULTS

Compared to baseline, mean ADC increased significantly for responders within 3 hours post-DEB-TACE (0.73 ± 0.20 mm(2) /s vs. 0.99 ± 0.28 mm(2) /s × 10(-3) (P = 0.001)). There was no significant change in ADC within 3 hours for nonresponders. ADC RC threshold of 20% immediately post-DEB-TACE showed 100% sensitivity and specificity in predicting anatomical response at 1 and 3 months with patients with ≥20% ADC increase demonstrated significantly prolonged mean overall survival compared to others (25.4 vs. 13.3 months (P = 0.017)).

CONCLUSION

ADC relative change of ≥20% immediately post-DEB-TACE is an accurate predictor of objective and quantitative treatment response and prolonged survival in unresectable HCC.

Diffusion-weighted imaging of the liver: techniques and applications

Diffusion-weighted imaging (DWI) is a technique that assesses the cellularity, tortuosity of the extracellular/extravascular space, and cell membrane density based on differences in water proton mobility in tissues. The strength of the diffusion weighting is reflected by the b value. DWI using several b values enables the quantification of the apparent diffusion coefficient. DWI is increasingly used in liver imaging for multiple reasons: it can add useful qualitative and quantitative information to conventional imaging sequences; it is acquired relatively quickly; it is easily incorporated into existing clinical protocols; and it is a noncontrast technique.

Apparent diffusion coefficients of normal uterus in premenopausal women with 3.0-T magnetic resonance imaging

PURPOSE

To investigate the apparent diffusion coefficients (ADCs) of the normal uterine zonal structures (myometrium, endometrium, and junctional zone) during different phases of the menstrual cycle among premenopausal women with different age groups.

MATERIALS AND METHODS

Magnetic resonance (MR) images of 67 healthy women were obtained during the midproliferative and midsecretory phases. They were further divided into 3 age groups: group A (age range, 20-29 years); group B (age range, 30-39 years), and group C (mean age, 44.62 years; age range, 40-49 years). All the women underwent 3.0-T MR scanning twice. The ADC values were compared among each uterine zonal structure and 3 age groups and were calculated between the midproliferative and midsecretory phase.

RESULTS

The ADC values among each uterine zonal structures were significantly different from one another (P < 0.001). The ADC values for endometrium in women in their 30s were higher than those in their 20s and in their 30s during the midproliferative and midsecretory phases (P < 0.05), and the ADC values for endometrium in each age groups were lower during the midproliferative phase than those during the midsecretory phase (P < 0.05), but there were no statistical differences in the myometrium and the junctional zone between the 2 phases or among age groups (P > 0.05).

CONCLUSION

These preliminary results suggested that the zone, age, and phase of the menstrual cycle in premenopausal women should be considered when interpreting the ADC values of uterine structures (especially for endometrium).

Analytical methods for brain targeted delivery system in vivo: perspectives on imaging modalities and microdialysis

Since the introduction of microdialysis in 1974, the semi-invasive analytical method has grown exponentially. Microdialysis is one of the most potential analysis technologies of pharmacological drug delivery to the brain. In recent decades, analysis of chemicals targeting the brain has led to many improvements. It seems likely that fluorescence imaging was limited to ex vivo and in vitro applications with the exception of several intravital microscopy and photographic imaging approaches. X-ray computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) have been commonly utilized for visualization of distribution and therapeutic effects of drugs. The efficient analytical methods for studies of brain-targeting delivery system is a major challenge in detecting the disposition as well as the variances of the factors that regulate the substances delivery into the brain. In this review, we highlight some of the ongoing trends in imaging modalities and the most recent developments in the field of microdialysis of live animals and present insights into exploiting brain disease for therapeutic and diagnostics purpose.

Image-based biomarkers in clinical practice

The growth of functional and metabolically informative imaging is eclipsing anatomic imaging alone in clinical practice. The recognition that magnetic resonance (MR) and positron emission tomography (PET)-based treatment planning and response assessment are essential components of clinical practice and furthermore offer the potential of quantitative analysis being important. Extracting the greatest benefit from these imaging techniques will require refining the best combinations of multimodality imaging through well-designed clinical trials that use robust image-analysis tools and require substantial computer based infrastructure. Through these changes and enhancements, image-based biomarkers will enhance clinical decision making and accelerate the progress that is made through clinical trial research.

The ESTRO Breur Lecture 2009. From population to voxel-based radiotherapy: exploiting intra-tumour and intra-organ heterogeneity for advanced treatment of non-small cell lung cancer

Evidence is accumulating that radiotherapy of non-small cell lung cancer patients can be optimized by escalating the tumour dose until the normal tissue tolerances are met. To further improve the therapeutic ratio between tumour control probability and the risk of normal tissue complications, we firstly need to exploit inter patient variation. This variation arises, e.g. from differences in tumour shape and size, lung function and genetic factors. Secondly improvement is achieved by taking into account intra-tumour and intra-organ heterogeneity derived from molecular and functional imaging. Additional radiation dose must be delivered to those parts of the tumour that need it the most, e.g. because of increased radio-resistance or reduced therapeutic drug uptake, and away from regions inside the lung that are most prone to complication. As the delivery of these treatments plans is very sensitive for geometrical uncertainties, probabilistic treatment planning is needed to generate robust treatment plans. The administration of these complicated dose distributions requires a quality assurance procedure that can evaluate the treatment delivery and, if necessary, adapt the treatment plan during radiotherapy.

Multifunctional Nanocarriers for diagnostics, drug delivery and targeted treatment across blood-brain barrier: perspectives on tracking and neuroimaging

Nanotechnology has brought a variety of new possibilities into biological discovery and clinical practice. In particular, nano-scaled carriers have revolutionalized drug delivery, allowing for therapeutic agents to be selectively targeted on an organ, tissue and cell specific level, also minimizing exposure of healthy tissue to drugs. In this review we discuss and analyze three issues, which are considered to be at the core of nano-scaled drug delivery systems, namely functionalization of nanocarriers, delivery to target organs and in vivo imaging. The latest developments on highly specific conjugation strategies that are used to attach biomolecules to the surface of nanoparticles (NP) are first reviewed. Besides drug carrying capabilities, the functionalization of nanocarriers also facilitate their transport to primary target organs. We highlight the leading advantage of nanocarriers, i.e. their ability to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells surrounding the brain that prevents high-molecular weight molecules from entering the brain. The BBB has several transport molecules such as growth factors, insulin and transferrin that can potentially increase the efficiency and kinetics of brain-targeting nanocarriers. Potential treatments for common neurological disorders, such as stroke, tumours and Alzheimer's, are therefore a much sought-after application of nanomedicine. Likewise any other drug delivery system, a number of parameters need to be registered once functionalized NPs are administered, for instance their efficiency in organ-selective targeting, bioaccumulation and excretion. Finally, direct in vivo imaging of nanomaterials is an exciting recent field that can provide real-time tracking of those nanocarriers. We review a range of systems suitable for in vivo imaging and monitoring of drug delivery, with an emphasis on most recently introduced molecular imaging modalities based on optical and hybrid contrast, such as fluorescent protein tomography and multispectral optoacoustic tomography. Overall, great potential is foreseen for nanocarriers in medical diagnostics, therapeutics and molecular targeting. A proposed roadmap for ongoing and future research directions is therefore discussed in detail with emphasis on the development of novel approaches for functionalization, targeting and imaging of nano-based drug delivery systems, a cutting-edge technology poised to change the ways medicine is administered.

Carbogen breathing increases prostate cancer oxygenation: a translational MRI study in murine xenografts and humans

Hypoxia has been associated with poor local tumour control and relapse in many cancer sites, including carcinoma of the prostate. This translational study tests whether breathing carbogen gas improves the oxygenation of human prostate carcinoma xenografts in mice and in human patients with prostate cancer. A total of 23 DU145 tumour-bearing mice, 17 PC3 tumour-bearing mice and 17 human patients with prostate cancer were investigated. Intrinsic susceptibility-weighted MRI was performed before and during a period of carbogen gas breathing. Quantitative R(2)* pixel maps were produced for each tumour and at each time point and changes in R(2)* induced by carbogen were determined. There was a mean reduction in R(2)* of 6.4% (P=0.003) for DU145 xenografts and 5.8% (P=0.007) for PC3 xenografts. In all, 14 human subjects were evaluable; 64% had reductions in tumour R(2)* during carbogen inhalation with a mean reduction of 21.6% (P=0.0005). Decreases in prostate tumour R(2)* in both animal models and human patients as a result of carbogen inhalation suggests the presence of significant hypoxia. The finding that carbogen gas breathing improves prostate tumour oxygenation provides a rationale for testing the radiosensitising effects of combining carbogen gas breathing with radiotherapy in prostate cancer patients.

Hypoxia in prostate cancer: correlation of BOLD-MRI with pimonidazole immunohistochemistry-initial observations

PURPOSE

To investigate the ability of blood oxygen level-dependent (BOLD) MRI to depict clinically significant prostate tumor hypoxia.

METHODS AND MATERIALS

Thirty-three patients with prostate carcinoma undergoing radical prostatectomy were studied preoperatively, using gradient echo sequences without and with contrast medium enhancement, to map relative tissue oxygenation according to relaxivity rates and relative blood volume (rBV). Pimonidazole was administered preoperatively, and whole-mount sections of selected tumor-bearing slices were stained for pimonidazole fixation and tumor and nontumor localization. Histologic and imaging parameters were independently mapped onto patient prostate outlines. Using 5-mm grids, 861 nontumor grid locations were compared with 237 tumor grids (with >50% tumor per location) using contingency table analysis with respect to the ability of imaging to predict pimonidazole staining.

RESULTS

Twenty patients completed the imaging and histologic protocols. Pimonidazole staining was found in 33% of nontumor and in 70% of tumor grids. The sensitivity of the MR relaxivity parameter R(2)* in depicting tumor hypoxia was high (88%), improving with the addition of low rBV information (95%) without changing specificity (36% and 29%, respectively). High R(2)* increased the positive predictive value for hypoxia by 6% (70% to 76%); conversely, low R(2)* decreased the likelihood of hypoxia being present by 26% (70% to 44%) and by 41% (71% to 30%) when combined with rBV information.

CONCLUSION

R(2)* maps from BOLD-MRI have high sensitivity but low specificity for defining intraprostatic tumor hypoxia. This together with the negative predictive value of 70% when combined with blood volume information makes BOLD-MRI a potential noninvasive technique for mapping prostatic tumor hypoxia.