Prognostic utility of diffusion-weighted MRI in oesophageal cancer: is apparent diffusion coefficient a potential marker of tumour aggressiveness?

From twilight to starlight? Debating the role of chemoradiotherapy in gastric cancer in the D2 dissection era

Patients affected by resectable locally advanced gastric cancer (GC) should receive perioperative chemotherapy as a standard of care. However, an additional benefit of adjuvant chemoradiation (CRT) has been negated by modern trials in the era of extended surgical dissection, and CRT is currently only considered on an individual basis in case of suboptimal resection. However, the dismal prognosis of GC and the modest treatment completion rates of perioperative chemotherapy have pushed to reconsider CRT, particularly as a preoperative treatment, in light of modern treatment techniques, advances in the understanding of the immune landscape and development of targeted agents. The aim of this review is to critically assess the historical role of CRT, the limitations of current evidence and to debate its potential role in an integrated neoadjuvant strategy for patients with resectable GC.

Progress of magnetic resonance imaging radiomics in preoperative lymph node diagnosis of esophageal cancer

Esophageal cancer, also referred to as esophagus cancer, is a prevalent disease in the cardiothoracic field and is a leading cause of cancer-related mortality in China. Accurately determining the status of lymph nodes is crucial for developing treatment plans, defining the scope of intraoperative lymph node dissection, and ascertaining the prognosis of patients with esophageal cancer. Recent advances in diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (MRI) have improved the effectiveness of MRI for assessing lymph node involvement, making it a beneficial tool for guiding personalized treatment plans for patients with esophageal cancer in a clinical setting. Radiomics is a recently developed imaging technique that transforms radiological image data from regions of interest into high-dimensional feature data that can be analyzed. The features, such as shape, texture, and waveform, are associated with the cancer phenotype and tumor microenvironment. When these features correlate with the clinical disease outcomes, they form the basis for specific and reliable clinical evidence. This study aimed to review the potential clinical applications of MRI-based radiomics in studying the lymph nodes affected by esophageal cancer. The combination of MRI and radiomics is a powerful tool for diagnosing and treating esophageal cancer, enabling a more personalized and effectual approach.

[18F]FDG-PET-Based Personalized Radiotherapy Dose Prescription

PET imaging with 2'-deoxy-2'-[18F]fluoro-D-glucose ([18F]FDG) has become one of the pillars in the management of malignant diseases. It has proven value in diagnostic workup, treatment policy, follow-up, and as prognosticator for outcome. [18F]FDG is widely available and standards have been developed for PET acquisition protocols and quantitative analyses. More recently, [18F]FDG-PET is also starting to be appreciated as a decision aid for treatment personalization. This review focuses on the potential of [18F]FDG-PET for individualized radiotherapy dose prescription. This includes dose painting, gradient dose prescription, and [18F]FDG-PET guided response-adapted dose prescription. The current status, progress, and future expectations of these developments for various tumor types are discussed.

The clinical value of DCE-MRI for differentiating secondary laryngeal cartilage lesions

To explore the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the assessment of laryngeal cartilage lesions. In this study, 3 groups of cases were selected, including 16 cases benign lesions of the laryngopharynx as the benign group, 17 cases malignant lesions of laryngopharynx as the malignant group and 23 healthy adults as the control group. Conventional magnetic resonance imaging and DCE-MRI were performed with a 3.0 T MR scanner. cutoff, sensitivity, specificity and area under the curve values were calculated via receiver operating characteristic curve analysis based on the pathologic findings of surgically resected specimens. There were significant differences in the values of the volume transfer constant (Ktrans), the rate constant between the extravascular extracellular space and blood plasma (Kep) and The extravascular extracellular space fractional volume (Ve) between the control, benign and malignant groups (P < .005). Among the 3 groups, the malignant group had the highest Ktrans and Ve values (0.8681 ± 0.3034 and 0.6186 ± 0.2405, respectively), and the benign group had the highest Kep value (2.445 ± 0.7346). The cutoff points of the Ktrans, Kep, and Ve values of the control, benign and malignant groups were 0.39, 1.261, and 0.195; 0.471, 0.964, and 0.235; and 0.706, 2.005, and 0.659, respectively. The Ktrans, Kep, and Ve values obtained via DCE-MRI may enable differentiating laryngeal cartilage lesions. DCE-MRI can be used to evaluate laryngeal cartilage lesions accurately and quantitatively.

Geometrical Comparison and Quantitative Evaluation of 18F-FDG PET/CT- and DW-MRI-Based Target Delineation Before and During Radiotherapy for Esophageal Squamous Carcinoma

Background and Purpose

This study aimed to evaluate the geometrical differences in and metabolic parameters of ¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography (¹⁸F-FDG PET-CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) performed before and during radiotherapy (RT) for patients with esophageal cancer based on the three-dimensional CT (3DCT) medium and explore whether the high signal area derived from DW-MRI can be used as a tool for an individualized definition of the volume in need of dose escalation for esophageal squamous cancer.

Materials and Methods

Thirty-two patients with esophageal squamous cancer sequentially underwent repeated 3DCT, ¹⁸F-FDG PET-CT, and enhanced MRI before the initiation of RT and after the 15th fraction. All images were fused with 3DCT images through deformable registration. The gross tumor volume (GTV) was delineated based on PET Edge on the first and second PET-CT images and defined as GTV_PETpre and GTV_PETdur, respectively. GTV_DWIpre and GTV_DWIdur were delineated on the first and second DWI and corresponding T₂-weighted MRI (T₂W-MRI)-fused images. The maximum, mean, and peak standardized uptake values (SUVs; SUV_max, SUV_mean, and SUV_peak, respectively); metabolic tumor volume (MTV); and total lesion glycolysis(TLG) and its relative changes were calculated automatically on PET. Similarly, the minimum and mean apparent diffusion coefficient (ADC; ADC_min and ADC_mean) and its relative changes were measured manually using ADC maps.

Results

The volume of GTV_CT exhibited a significant positive correlation with that of GTV_PET and GTV_DWI (both p < 0.001). Significant differences were observed in both ADCs and ¹⁸F-FDG PET metabolic parameters before and during RT (both p < 0.001). No significant correlation was observed between SUVs and ADCs before and during RT (p = 0.072–0.944) and between ∆ADCs and ∆SUVs (p = 0.238–0.854). The conformity index and degree of inclusion of GTV_PETpre to GTV_DWIpre were significantly higher than those of GTV_PETdur to GTV_DWIdur (both p < 0.001). The maximum diameter shrinkage rate (∆LD_DWI) (24%) and the tumor volume shrinkage rate (VRR_DWI) (60%) based on DW-MRI during RT were significantly greater than the corresponding PET-based ∆LD_PET (14%) and VRR_PET (41%) rates (p = 0.017 and 0.000, respectively).

Conclusion

Based on the medium of CT images, there are significant differences in spatial position, biometabolic characteristics, and the tumor shrinkage rate for GTVs derived from ¹⁸F-FDG PET-CT and DW-MRI before and during RT for esophageal squamous cancer. Further studies are needed to determine if DW-MRI will be used as tool for an individualized definition of the volume in need of dose escalation.

Radiomics in the Setting of Neoadjuvant Radiotherapy: A New Approach for Tailored Treatment

Simple Summary

This review based on a literature search aims at showing the impact of Texture Analysis in the prediction of response to neoadjuvant radiotherapy and/or chemoradiotherapy. The manuscript explores radiomics approaches in different fields of neoadjuvant radiotherapy, including esophageal cancer, lung cancer, sarcoma and rectal cancer in order to shed a light in the setting of neoadjuvant radiotherapy that can be used to tailor the best subsequent therapeutical strategy.

Abstract

Introduction: Neoadjuvant radiotherapy is currently used mainly in locally advanced rectal cancer and sarcoma and in a subset of non-small cell lung cancer and esophageal cancer, whereas in other diseases it is under investigation. The evaluation of the efficacy of the induction strategy is made possible by performing imaging investigations before and after the neoadjuvant therapy and is usually challenging. In the last decade, texture analysis (TA) has been developed to help the radiologist to quantify and identify the parameters related to tumor heterogeneity, which cannot be appreciated by the naked eye. The aim of this narrative is to review the impact of TA on the prediction of response to neoadjuvant radiotherapy and or chemoradiotherapy. Materials and Methods: Key references were derived from a PubMed query. Hand searching and ClinicalTrials.gov were also used. Results: This paper contains a narrative report and a critical discussion of radiomics approaches in different fields of neoadjuvant radiotherapy, including esophageal cancer, lung cancer, sarcoma, and rectal cancer. Conclusions: Radiomics can shed a light on the setting of neoadjuvant therapies that can be used to tailor subsequent approaches or even to avoid surgery in the future. At the same, these results need to be validated in prospective and multicenter trials.

Predicting the effects of radiotherapy based on diffusion kurtosis imaging in a xenograft mouse model of esophageal carcinoma

The aim of the present study was to assess the predictive value of diffusion kurtosis imaging (DKI) on the effects of radiotherapy in a xenograft model of esophageal cancer. A total of 40 tumor-bearing mice, established by injection of Eca-109 cells in nude mice, were used. The experimental group (n=24) received a single dose of 15 Gy (6 MV by X-ray), and the control group (n=16) did not receive any treatment. Tumor volume, apparent diffusion coefficient (ADC), mean kurtosis (MK) and mean diffusivity (MD) of the two groups were compared, and the expression of aquaporin (AQP) 3 and necrosis ratio at matched time points in xenografts were also observed. There was a significant difference between the two groups from the 7th day of radiotherapy onwards; the xenograft volume of the experimental group was significantly smaller compared with the control group (P<0.05). On the 3rd day, the ADC and MD of the experimental group was significantly higher compared with the control group, and MK was significantly lower compared with the control group (P<0.05). On the 3rd day, AQP3 expression in the experimental group was lower compared with the control group, and the proportion of necrotic cells was higher compared with the control group (P<0.05). Single large fraction dose radiotherapy inhibited the growth of a xenografted esophageal tumor. Changes in ADC, MK and MD were observed prior to morphological changes in the tumor. The change in AQP3 expression and necrosis ratio was in also agreement with the DKI parameters assessed. DKI may thus provide early predictive ability on the effect of radiotherapy in esophageal carcinoma.

Predictive Value of Early Response to Chemoradiotherapy in Advanced Esophageal Squamous Cell Carcinoma by Diffusion-Weighted MR Imaging

Objective:

To explore the value of diffusion-weighted imaging for early response detection of locally advanced esophageal squamous cell carcinoma with concurrent chemoradiotherapy.

Methods:

Fifty-five (42 males, 13 females) patients with locally advanced esophageal cancer who were undergoing chemoradiotherapy were recruited for this study. Diffusion-weighted imaging was performed in all patients before therapy, at the first weekend, the second weekend, and the end of chemoradiotherapy. The rate of change in apparent diffusion coefficient value and the maximum diameter between pretherapy and posttherapy were calculated.

Results:

Fifty-five patients with locally advanced esophageal squamous cell carcinoma were classified as responders (40 cases) and nonresponders (15 cases). Before chemoradiotherapy, the responders group had a significantly lower apparent diffusion coefficient values than the nonresponders group (t = −4.815, P = .000). At the 3 time points after chemoradiotherapy (first weekend, second weekend, and the end of chemoradiotherapy), there was no statistically significant difference in apparent diffusion coefficient values between responders and nonresponders (P > .05). The responders group had a significantly higher rate of change in apparent diffusion coefficient value than the nonresponders group at each time point (P < .05). At the first weekend of chemoradiotherapy, the rate of change in the maximum diameter was not significantly different in the 2 groups (t = 0.928, P = .357). There was a negative correlation between the tumor apparent diffusion coefficient value of pretherapy and the reduction ratio of tumor maximum diameter at the end of chemoradiotherapy (r = −0.592, P = .000).

Conclusions:

The change rate of apparent diffusion coefficient value by the end of the first week after beginning chemoradiotherapy may be a sensitive indicator to detect the early response to locally advanced esophageal squamous cell carcinoma.

Esophagus and Stomach: Is There a Role for MR Imaging?

MR imaging has been increasingly used in the diagnostic work-up of benign and malignant conditions of the gastroesophageal tract. The use of an adequate MR imaging protocol is crucial, although standardization of imaging studies is still far from being implemented. Research on MR imaging-based biomarkers show promising results in assessing tumor aggressiveness and prognosis, and in the evaluation of response to treatment, both in esophageal and gastric cancers.

Optimal timing for prediction of pathologic complete response to neoadjuvant chemoradiotherapy with diffusion-weighted MRI in patients with esophageal cancer

OBJECTIVE

This study was conducted in order to determine the optimal timing of diffusion-weighted magnetic resonance imaging (DW-MRI) for prediction of pathologic complete response (pCR) to neoadjuvant chemoradiotherapy (nCRT) for esophageal cancer.

METHODS

Patients with esophageal adenocarcinoma or squamous cell carcinoma who planned to undergo nCRT followed by surgery were enrolled in this prospective study. Patients underwent six DW-MRI scans: one baseline scan before the start of nCRT and weekly scans during 5 weeks of nCRT. Relative changes in mean apparent diffusion coefficient (ADC) values between the baseline scans and the scans during nCRT (ΔADC(%)) were compared between pathologic complete responders (pCR) and non-pCR (tumor regression grades 2-5). The discriminative ability of ΔADC(%) was determined based on the c-statistic.

RESULTS

A total of 24 patients with 142 DW-MRI scans were included. pCR was observed in seven patients (29%). ΔADC(%) from baseline to week 2 was significantly higher in patients with pCR versus non-pCR (median [IQR], 36% [30%, 41%] for pCR versus 16% [14%, 29%] for non-pCR, p = 0.004). The ΔADC(%) of the second week in combination with histology resulted in the highest c-statistic for the prediction of pCR versus non-pCR (0.87). The c-statistic of this model increased to 0.97 after additional exclusion of patients with a small tumor volume (< 7 mL, n = 3) and tumor histology of the resection specimen other than adenocarcinoma or squamous cell carcinoma (n = 1).

CONCLUSION

The relative change in tumor ADC (ΔADC(%)) during the first 2 weeks of nCRT is the most predictive for pathologic complete response to nCRT in esophageal cancer patients.

KEY POINTS

• DW-MRI during the second week of neoadjuvant chemoradiotherapy is most predictive for pathologic complete response in esophageal cancer. • A model including ΔADCweek 2was able to discriminate between pathologic complete responders and non-pathologic complete responders in 87%. • Improvements in future MRI studies for esophageal cancer may be obtained by incorporating motion management techniques.

ADC correlation with Sirtuin1 to assess early chemoradiotherapy response of locally advanced esophageal carcinoma patients

Aims

To determine the biological correlation between apparent diffusion coefficient (ADC) values and Sirtuin1 (SIRT1) levels of tumour tissues in patients with esophageal carcinoma (EC), and to ascertain the treatment biomarker of ADC in predicting the early response of patients undergoing definitive chemoradiotherapy (CRT).

Methods

A total of 66 patients were enrolled, and the specimens of tumour tissues were collected before treatment to perform immunohistochemical (IHC) examinations and quantify the levels of SIRT1. Then all patients were given two esophageal magnetic resonance imaging (MRI) examinations with diffused weighed imaging (DWI) including pretreatment and intra-treatment (1~2 weeks after the start of radiotherapy). The regions of interest (ROIs) were contoured according to the stipulated rules in advance using off-line software, and the values of the ADC in the ROIs were generated automatically. Then, the values of the ADC at baseline and intra-treatment were labeled as pre-ADC and intra-ADC respectively, and ΔADC, ADC_ratio were calculated. Pearson’s correlation coefficients were acquired to estimate the correlation between each of ADC values and SIRT1 levels. Spearman’s rank correlation coefficients were acquired to estimate the correlation between early response and the values of each ADC. Receptor operation characteristics (ROC) curves were constructed to estimate the accuracy of the ADC in predicting the early response of CRT.

Results

The findings of this study showed different correlations between ADC values and the levels of SIRT1 (ΔADC: r = − 0.943, P = 0.002; ADC_ratio: r = − 0.911, P = 0.000; intra-ADC: r = − 0.748, P = 0.002; pre-ADC: r = 0.109, P = 0.558). There was a positive correlation between ΔADC and early response to treatment (ρ = 0.615, P = 0.023), and multivariable logistic regression revealed that ΔADC was significantly associated with short-term response of CRT in esophageal carcinoma patients.

Conclusions

In summary, early increases in ADC may facilitate the predication of early CRT response in patients with esophageal squamous cell carcinoma (ESCC), which may be attributed to the different correlation between ADC changes and SIRT1 expression.

Prognostic value of 18F-FDG PET/MR imaging biomarkers in oesophageal squamous cell carcinoma

PURPOSE

To correlate the clinical stage and prognosis of oesophageal squamous cell carcinoma (SCC) using the imaging biomarkers from integrated positron emission tomography (PET)/magnetic resonance imaging (MRI).

METHODS

In total, 54 consecutive patients with oesophageal SCC who receive PET/MRI scan were recruited before treatment. The imaging biomarkers used were the mean and minimal apparent diffusion coefficients (ADC_mean and ADC_min), standardized uptake value (SUV), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) of tumours. The correlation between each imaging biomarker and survival was investigated using the Cox proportional hazards model.

RESULTS

ADC_mean was negatively correlated with SUV_max (r = -0.414, P =  0.025). ADC_min was negatively correlated with SUV_max (r = -0.423, P =  0.001) and SUV_peak (r = -0.402, P =  0.003), and was significantly lower in M1 than in M0 tumours (829.6 vs. 1069.8, P = 0.005). MTV was significantly higher in T3 + (P <  0.001), N1 + (P = 0.014) and TNM stage III + (P <  0.001) tumours. TLG was significantly higher in T3 + (P <  0.001), N1 + (P <  0.001), M1 (P =  0.045) and TNM stage III + (P <  0.001) tumours. The MTV/ADC_min ratio exhibited the highest area under the receiver operating characteristic curve (AUROC) for predicting M1 and advanced TNM stage tumours. Multivariate analysis for progression-free survival (PFS) and overall survival (OS) showed that a larger MTV/ADC_min was associated with a shorter PFS and OS (P = 0.024 and 0.046, respectively).

CONCLUSION

The imaging biomarkers in integrated PET/MRI may predict clinical stage and survival in patients with oesophageal SCC.

Contribution of magnetic resonance imaging to the management of esophageal diseases: A systematic review

PURPOSE

Currently available imaging modalities used to investigate the esophagus are irradiating or limited to the analysis of the esophageal lumen. Magnetic resonance imaging (MRI) is a non-invasive and non-radiating imaging technique that provides high degrees of soft tissue contrast. Newly developed fast MRI sequences allow for both morphological and functional assessment of the esophageal body and esophagogastric junction. The purpose of this systematic review was to identify the contribution of MRI to the diagnosis and management of esophageal diseases, such as gastroesophageal reflux, esophageal motility disorders, esophageal neoplasms, and portal hypertension.

METHODS

We performed a systematic search of the Medline (via Ovid), EMBASE (via Ovid), PubMed and Cochrane Library databases from inception to December 2018 inclusively, using the MESH major terms "magnetic resonance imaging" AND "esophagus".

RESULTS

The initial search retrieved 310 references, of which 56 were found to be relevant for the study. References were analysed and classified in different subheadings: MRI protocols for the esophagus, gastroesophageal reflux disease, achalasia and other esophageal motility disorders, esophageal cancer, portal hypertension and other esophageal conditions.

CONCLUSION

MR Esophagography might become a non-invasive, non-irradiating technique of choice following diagnostic esophagogastroduodenoscopy for the assessment of esophageal diseases.

Diffusion-weighted MRI with ADC mapping for response prediction and assessment of oesophageal cancer: A systematic review

PURPOSE

The aim was to perform a systematic review on the value of diffusion-weighted MRI (DW-MRI) with apparent diffusion coefficient (ADC) mapping in the prediction and assessment of response to chemo- and/or radiotherapy in oesophageal cancer.

MATERIALS AND METHODS

A systematic search was performed on Pubmed, Embase, Medline and Cochrane databases. Studies that evaluated the ADC for response evaluation before, during or after chemo- and/or radiotherapy were included. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the quality of the included studies.

RESULTS

Fourteen studies, comprising 516 patients, in which the response to treatment in oesophageal cancer was evaluated on ADC maps were included. Acquisition parameter settings for DW-MRI and ROI placement varied substantially. The reference standard was RECIST or endoscopic assessment in eight non-surgery studies and histopathology after surgery in six studies. A high pre-treatment ADC significantly correlated with good response in three out of 12 studies; conversely, one study reported a significantly higher pre-treatment ADC in poor responders. In five out of eight studies good responders showed a significantly larger relative increase in ADC two weeks after the onset of treatment (range 23-59%) than poor responders (range 1.5-17%). After chemo- and/or radiotherapy ADC results varied considerably, amongst others due to large variation in the interval between completion of therapy and DW-MRI.

CONCLUSION

DW-MRI for response evaluation to chemo- and/or radiotherapy in oesophageal cancer shows variable methods and results. A large relative ADC increase after two weeks of treatment seems most predictive for good response.

Role of advanced magnetic resonance imaging in the assessment of malignancies of the mediastinum

In the new era of functional magnetic resonance imaging (MRI), the utility of chest MRI is increasing exponentially due to several advances, including absence of ionizing radiation, excellent tissue contrast and high capability for lesion characterization and treatment monitoring. The application of several of these diagnostic weapons in a multiparametric fashion enables to better characterize thymic epithelial tumors and other mediastinal tumoral lesions, accurate assessment of the invasion of adjacent structures and detection of pathologic lymph nodes and metastasis. Also, “do not touch lesions” could be identified with the associated impact in the management of those patients. One of the hot-spots of the multiparametric chest MR is its ability to detect with acuity early response to treatment in patients with mediastinal malignant neoplasms. This has been related with higher rates of overall survival and progression free survival. Therefore, in this review we will analyze the current functional imaging techniques available (¹⁸F-Fluorodeoxiglucose positron emission tomography/computed tomography, diffusion-weighted imaging, dynamic contrast-enhanced MRI, diffusion tensor imaging and MR spectroscopy) for the evaluation of mediastinal lesions, with a focus in their correct acquisition and post-processing. Also, to review the clinical applications of these techniques in the diagnostic approach of benign and malignant conditions of the mediastinum.

CT scan and magnetic resonance diffusion-weighted imaging in the diagnosis and treatment of esophageal cancer

Value of computed tomography (CT) scan and diffusion-weighted imaging (DWI) in the diagnosis and treatment of esophageal cancer was investigated. Seventy-eight patients with esophageal cancer treated in Jinan Central Hospital (Jinan, China) from January 2013 to June 2014 were selected. All patients underwent CT scan and DWI examination, and their clinical history data were analyzed. DWI was conducted. The short-term curative effect and the 3-year survival rate of patients in the high apparent diffusion coefficient (ADC) value group and the low ADC value group were compared; ADC values in the complete remission (CR) group and the partial remission (PR) group were compared. The difference in value between the length of esophageal lesions and the length of pathological specimens measured by CT scan was significantly different from that detected via DWI examination with b=600, 800 and 1,000 sec/mm², respectively (P<0.05). The diagnostic rate of esophageal cancer via CT scan was significantly lower than that via DWI examination (P<0.05). After radiotherapy, the clinical control rate in the high ADC value group was significantly higher than that in the low ADC value group, and the 3-year survival rate in the former was significantly higher than that in the latter (P<0.05). In the 2nd week during radiotherapy and at the end of radiotherapy, the ADC values in the CR group were significantly higher than those in the PR group (P<0.05). In the 2nd week during radiotherapy and at the end of radiotherapy, ADC values were used to predict the CR rate of radiotherapy for esophageal cancer, and the areas under the receiver operating characteristic (ROC) curve were 0.776 and 0.935, respectively. Compared with CT scan, DWI has higher diagnostic rate and higher sensitivity. The length of esophageal tumor measured by DWI is close to that of pathological entity, which can guide the delineation of the target area of esophageal cancer.

MR Imaging of Mediastinal Masses

The mediastinum contains vital vascular and nonvascular structures and organs, and a wide variety of abnormalities may arise from this region of the thorax. Although mediastinal masses may be initially detected on chest radiography, cross-sectional imaging plays an important role in the identification and evaluation of mediastinal lesions, enabling the formulation of focused differential diagnoses and ultimately guiding management. Computed tomography (CT) is considered the imaging modality of choice for evaluating most mediastinal masses; however, the role of magnetic resonance (MR) imaging continues to expand, as it is superior to CT in differentiating between cystic and solid masses, identifying cystic and solid components within complex lesions, and distinguishing thymic hyperplasia and normal thymus from thymic epithelial neoplasms and other neoplasms. In addition, it facilitates the staging and restaging of patients with thymic epithelial neoplasms and other tumors that cannot undergo contrast-enhanced CT imaging due to severe contrast allergy and/or impaired renal function. As division of the mediastinum into specific compartments is beneficial for diagnostic and treatment planning purposes and facilitates communication between clinicians in a multidisciplinary setting, a new classification model based on cross-sectional imaging has been developed by the International Thymic Malignancy Interest Group (ITMIG) and accepted as a new standard. In this article, we describe the role of MR imaging in the evaluation of mediastinal masses in conjunction with the new mediastinal compartment classification system introduced by ITMIG.

Predictive value of initial FDG-PET features for treatment response and survival in esophageal cancer patients treated with chemo-radiation therapy using a random forest classifier

Purpose

In oncology, texture features extracted from positron emission tomography with 18-fluorodeoxyglucose images (FDG-PET) are of increasing interest for predictive and prognostic studies, leading to several tens of features per tumor. To select the best features, the use of a random forest (RF) classifier was investigated.

Methods

Sixty-five patients with an esophageal cancer treated with a combined chemo-radiation therapy were retrospectively included. All patients underwent a pretreatment whole-body FDG-PET. The patients were followed for 3 years after the end of the treatment. The response assessment was performed 1 month after the end of the therapy. Patients were classified as complete responders and non-complete responders. Sixty-one features were extracted from medical records and PET images. First, Spearman’s analysis was performed to eliminate correlated features. Then, the best predictive and prognostic subsets of features were selected using a RF algorithm. These results were compared to those obtained by a Mann-Whitney U test (predictive study) and a univariate Kaplan-Meier analysis (prognostic study).

Results

Among the 61 initial features, 28 were not correlated. From these 28 features, the best subset of complementary features found using the RF classifier to predict response was composed of 2 features: metabolic tumor volume (MTV) and homogeneity from the co-occurrence matrix. The corresponding predictive value (AUC = 0.836 ± 0.105, Se = 82 ± 9%, Sp = 91 ± 12%) was higher than the best predictive results found using the Mann-Whitney test: busyness from the gray level difference matrix (P < 0.0001, AUC = 0.810, Se = 66%, Sp = 88%). The best prognostic subset found using RF was composed of 3 features: MTV and 2 clinical features (WHO status and nutritional risk index) (AUC = 0.822 ± 0.059, Se = 79 ± 9%, Sp = 95 ± 6%), while no feature was significantly prognostic according to the Kaplan-Meier analysis.

Conclusions

The RF classifier can improve predictive and prognostic values compared to the Mann-Whitney U test and the univariate Kaplan-Meier survival analysis when applied to several tens of features in a limited patient database.

Diffusion-Weighted Magnetic Resonance Imaging as a Predictor of Outcome in Cervical Cancer After Chemoradiation

PURPOSE

To determine whether apparent diffusion coefficient (ADC) value is predictive of survival after definitive chemoradiation for cervical cancer independent of established imaging and clinical prognostic factors.

METHODS AND MATERIALS

Between 2011 and 2013, the pretreatment MRI scans for 69 patients treated with definitive chemoradiation for newly diagnosed cervical cancer were retrieved. Scans were acquired with a 1.5-T magnetic resonance scanner, including diffusion-weighted imaging sequences. Mean ADC value was measured within a region of interest in the primary cervical cancer on the baseline MRI scan. Baseline tumor maximum standardized uptake value on positron emission tomography/computed tomography was determined by the reading radiologist. Treatment included external beam radiation therapy to the pelvis followed by brachytherapy in 97%, and with concurrent weekly cisplatin in 99% of patients. Univariate and multivariate analyses were done to investigate the association of clinical and imaging variables with disease control and survival endpoints using a Cox proportional hazard test.

RESULTS

Median follow-up was 16.7 months (range, 3.1-44.2 months). The 1-year overall survival, locoregional recurrence-free survival, and disease-free survival rates were 91%, 86%, and 74%, respectively. The median ADC value was 0.941 × 10^-3 mm²/s (range, 0.256-1.508 × 10^-3 mm²/s). The median standardized uptake value in the primary tumor was 15 (range, 6.2-43.4). In multivariate analysis, higher ADC value (hazard ratio [HR] 0.36, 95% confidence interval [CI] 0.15-0.85, P=.02), higher stage (HR 2.4, 95% CI 1.1-5.5, P=.033), and nonsquamous histology (HR 0.23, 95% CI 0.07-0.82, P=.024) were independent predictors of disease-free survival.

CONCLUSIONS

The mean ADC value of the primary tumor on pretreatment MRI was the only imaging feature that was an independent predictor of disease-free survival in cervical cancer patients treated with chemoradiation. Further validation will be needed to determine whether ADC values may prove useful in identifying cervical patients at high risk of recurrence.

Apparent diffusion coefficient values detected by diffusion-weighted imaging in the prognosis of patients with locally advanced esophageal squamous cell carcinoma receiving chemoradiation

Purpose

Previous studies have demonstrated that apparent diffusion coefficient (ADC) values measured by magnetic resonance imaging have prognostic value in patients with esophageal squamous cell carcinoma (ESCC). However, the role of ADC needs to be validated in a cohort of Chinese ESCC patients. This study assessed the role of ADC in predicting the outcome of patients with ESCC treated only by chemoradiation in the People’s Republic of China.

Patients and methods

Seventy-three patients with local advanced ESCC were retrospectively analyzed in this study; none of the patients underwent surgery before or after chemoradiation. The ADC values of the primary tumors were determined by magnetic resonance imaging. The ADC values were then correlated with clinicopathological and other radiological parameters. Survival analysis was carried out to determine if ADC had an impact on survival of these patients.

Results

The median ADC value of the esophageal cancer tissue was 1.256*10⁻³ mm²/sec (range: 0.657–2.354*10⁻³ mm²/sec, interquartile range 0.606*10⁻³ mm²/sec). No clinicopathological or radiological parameters were associated with the ADC values except the sites of tumor tissues. ADC <1.076*10⁻³ mm²/sec predicted significantly worse survival in patients with ESCC (12.9 months vs undefined, P=0.0108).

Conclusion

The ADC value is a potent prognostic factor which can be used to predict the outcome of patients with ESCC treated only by chemoradiation.