Multiparametric MR imaging detects therapy efficacy of radioactive seeds brachytherapy in pancreatic ductal adenocarcinoma xenografts

Multi-parametric MRI (mpMRI) for treatment response assessment of radiation therapy

Magnetic resonance imaging (MRI) plays an important role in the modern radiation therapy (RT) workflow. In comparison with computed tomography (CT) imaging, which is the dominant imaging modality in RT, MRI possesses excellent soft-tissue contrast for radiographic evaluation. Based on quantitative models, MRI can be used to assess tissue functional and physiological information. With the developments of scanner design, acquisition strategy, advanced data analysis, and modeling, multiparametric MRI (mpMRI), a combination of morphologic and functional imaging modalities, has been increasingly adopted for disease detection, localization, and characterization. Integration of mpMRI techniques into RT enriches the opportunities to individualize RT. In particular, RT response assessment using mpMRI allows for accurate characterization of both tissue anatomical and biochemical changes to support decision-making in monotherapy of radiation treatment and/or systematic cancer management. In recent years, accumulating evidence have, indeed, demonstrated the potentials of mpMRI in RT response assessment regarding patient stratification, trial benchmarking, early treatment intervention, and outcome modeling. Clinical application of mpMRI for treatment response assessment in routine radiation oncology workflow, however, is more complex than implementing an additional imaging protocol; mpMRI requires additional focus on optimal study design, practice standardization, and unified statistical reporting strategy to realize its full potential in the context of RT. In this article, the mpMRI theories, including image mechanism, protocol design, and data analysis, will be reviewed with a focus on the radiation oncology field. Representative works will be discussed to demonstrate how mpMRI can be used for RT response assessment. Additionally, issues and limits of current works, as well as challenges and potential future research directions, will also be discussed.

Clinical Phase I/II Study: Local Disease Control and Survival in Locally Advanced Pancreatic Cancer Treated with Electrochemotherapy

Objective. To assess local disease control rates (LDCR) and overall survival (OS) in locally advanced pancreatic cancer (LAPC) treated with electrochemotherapy (ECT). Methods. Electrochemotherapy with bleomycin was performed in 25 LAPC patients who underwent baseline Magnetic Resonance Imaging (MRI) and/or Computed Tomography (CT) and Position Emission Tomography (PET) scans before ECT and 1 and 6 months post ECT. LDCR were assessed using Response Evaluation Criteria in Solid Tumors (RECIST 1.1) and Choi criteria. Needle electrodes with fixed linear (N-30-4B) or fixed hexagonal configurations (N-30-HG or I-40-HG or H-30-ST) or variable geometry (VGD1230 or VGD1240) (IGEA S.p.A., Carpi, Italy) were used to apply electric pulses. Pain evaluation was performed pre-ECT, after 1 month and after 6 months with ECT. Overall survival estimates were calculated by means of a Kaplan-Meier analysis. Results. At 1 month after ECT, 76% of patients were in partial response (PR) and 20% in stable disease (SD). Six months after ECT, 44.0% patients were still in PR and 12.0% in SD. A LDCR of 56.0% was reached six months after ECT: 13 patients treated with fixed geometry had a LDCR of 46.1%, while for the 12 patients treated with variable geometry, the LDCR was 66.7%. The overall survival median value was 11.5 months: for patients treated with fixed geometry the OS was 6 months, while for patients treated with variable geometry it was 12 months. Electrochemotherapy was well-tolerated and abdominal pain was rapidly resolved. Conclusions. Electrochemotherapy obtained good results in terms of LDCR and OS in LAPC. Multiple needle insertion in a variable geometry configuration optimized by pre-treatment planning determined an increase in LDCR and OS compared to a fixed geometry configuration.

Magnetic resonance severity index assessed by T1-weighted imaging for acute pancreatitis: correlation with clinical outcomes and grading of the revised Atlanta classification-a narrative review

Acute pancreatitis (AP) is a common disease that may involve pancreas and peripancreatic tissues with a prevalence of up to 50 per 100,000 individuals for year. The Atlanta classification was assessed for the first time in 1992 and modified in 2012 in order to describe morphological features of AP and its complications. AP can be morphologically distinguished in two main types: interstitial edematous pancreatitis (IEP) and necrotizing pancreatitis (NEP). This classification is very important because the presence of necrosis is directly linked to local or systemic complications, hospital stays and death. Magnetic resonance (MR) is very useful to characterize morphological features in AP and its abdominal complications. Particularly we would like to underline the diagnostic, staging and prognostic role of T1-weighted images with fat suppression that could be significant to assess many features of the AP inflammatory process and its complications (detection of the pancreatic contour, pancreatic necrosis, presence of haemorrhage). Signs of inflammatory and edema are instead observed by T1-weighted images. MR cholangiopancreatography (MRCP) is necessary to study the main pancreatic duct and the extrahepatic biliary tract and contrast-enhancement magnetic resonance imaging (MRI) allows to assess the extent of necrosis and vascular injuries.

Pancreatic neuroendocrine tumours: spectrum of imaging findings

Pancreatic neuroendocrine tumours (pNETs) are rare and heterogeneous group of neoplasms presenting with a wide variety of symptoms and biological behaviour, from indolent to aggressive ones. pNETs are stratified into functional or non-functional, because of their ability to produce metabolically active hormones. pNETs can be an isolate phenomenon or a part of a hereditary syndrome like von Hippel-Lindau syndrome or neurofibromatosis-1. The incidence has increased in the last years, also because of the improvement of cross-sectional imaging. Computed tomography (CT), magnetic resonance imaging (MRI) and functional imaging are the mainstay imaging modalities used for tumour detection and disease extension assessment, due to easy availability and better contrast/spatial resolution. Radiological imaging plays a fundamental role in detection, characterization and surveillance of pNETs and is involved in almost every stage of patients' management. Moreover, with specific indications and techniques, interventional radiology can also play a role in therapeutic management. Surgery is the treatment of choice, consisting of either partial pancreatectomy or enucleation of the primary tumour. This article reviews the radiologic features of different pNETs as well as imaging mimics, in order to help radiologists to avoid potential pitfalls, to reach the correct diagnosis and to support the multidisciplinary team in establishing the right treatment.

New advances in CT imaging of pancreas diseases: a narrative review

Computed tomography (CT) plays a pivotal role as a diagnostic tool in many diagnostic and diffuse pancreatic diseases. One of the major limits of CT is related to the radiation exposure of young patients undergoing repeated examinations. Besides the standard CT protocol, the most recent technological advances, such as low-voltage acquisitions with high performance X-ray tubes and iterative reconstructions, allow for significant optimization of the protocol with dose reduction. The variety of CT tools are further expanded by the introduction of dual energy: the production of energy-selective images (i.e., virtual monochromatic images) improves the image contrast and lesion detection while the material-selective images (e.g., iodine maps or virtual unenhanced images) are valuable for lesion detection and dose reduction. The perfusion techniques provide diagnostic and prognostic information lesion and parenchymal vascularization and interstitium. Both dual energy and perfusion CT have the potential for pushing the limits of conventional CT from morphological evaluation to quantitative imaging applied to inflammatory and oncological diseases. Advances in post-processing of CT images, such as pancreatic volumetry, texture analysis and radiomics provide relevant information for pancreatic function but also for the diagnosis, management and prognosis of pancreatic neoplasms. Artificial intelligence is promising for optimization of the workflow in qualitative and quantitative analyses. Finally, basic concepts on the role of imaging on screening of pancreatic diseases will be provided.

Diffusion-Weighted Imaging in Oncology: An Update

To date, diffusion weighted imaging (DWI) is included in routine magnetic resonance imaging (MRI) protocols for several cancers. The real additive role of DWI lies in the "functional" information obtained by probing the free diffusivity of water molecules into intra and inter-cellular spaces that in tumors mainly depend on cellularity. Although DWI has not gained much space in some oncologic scenarios, this non-invasive tool is routinely used in clinical practice and still remains a hot research topic: it has been tested in almost all cancers to differentiate malignant from benign lesions, to distinguish different malignant histotypes or tumor grades, to predict and/or assess treatment responses, and to identify residual or recurrent tumors in follow-up examinations. In this review, we provide an up-to-date overview on the application of DWI in oncology.

A review on the efficacy and safety of iodine-125 seed implantation in unresectable pancreatic cancers

Background: Pancreatic cancers are the common digestive system tumors with poor prognosis and due to its late diagnosis, surgical resection does not remain a viable treatment option in about 80% of patients. Amongst different treatment options, radioactive 125I seed implantation therapy has also emerged as a good alternative in non-resectable pancreatic cancer patients.Purpose: The present review describes the efficacy and safety of iodine-125 seed implantation in unresectable pancreatic cancers in preclinical and clinical studies.Results: In this technique, small radioactive particles are implanted inside the tumor cells to produce the sustain effects. Due to the short radial distance of these radiations, there is a selective and efficient killing of cancer cells without any significant injury to the neighboring cells. Amongst the different methods for implanting 125I seeds in the pancreatic tissues, CT scan or ultrasound-guided percutaneous seed implantation is preferred as it offers shorter operative time, lesser bleeding, early recovery, lesser complications, and low medical costs. The clinical studies have shown that radioactive 125I seed implantation is a good option for the management of local tumor growth, pain palliation, and improvement in the life span of patients suffering from unresectable pancreatic cancer.Conclusion: It may be employed either alone or in combination with cryotherapy, existing chemotherapy, bypass surgery or radiations to achieve the optimal results in these patients. Nevertheless, there is a need to formulate a uniform dose and procedure to achieve homogeneity and develop references for clinical practices.

PET/CT in brachytherapy early response evaluation of pancreatic ductal adenocarcinoma xenografts: comparison with apparent diffusion coefficient from diffusion-weighted MR imaging

OBJECTIVE

To evaluate the feasibility of using PET/CT and diffusion-weighted magnetic resonance imaging (DW-MRI) to monitor the early response of pancreatic ductal adenocarcinoma (PDAC) xenografts to brachytherapy, and to determine whether maximum standardized uptake value (SUVmax) correlate with apparent diffusion coefficient (ADC).

MATERIALS AND METHODS

SW1990 human PDAC were subcutaneously implanted in 20 nude mice. They were randomly divided into 125-Iodine (125I) seeds and blank seeds group. PET/CT and DW-MRI were performed at pretreatment and 5 days after therapy. SUVmax and ADC values were calculated, respectively. The correlation between SUVmax and ADC values was analyzed by the Pearson correlation test.

RESULTS

The SUVmax were significantly decreased between pretreatment and 5 days after 125I seeds treatment (p < 0.001) and between two groups (p < 0.001). And the ADC values were significantly increased between pretreatment and 5 days after 125I seeds treatment (p < 0.001) and between two groups (p < 0.001). While in the bank seeds group, there were no significantly difference between pretreatment and after treatment in SUVmax and ADC values (p = 0.057; p = 0.397). SUVmax and ADC correlated significantly and negatively before treatment in both groups (r = - 0.964, R2 = 0.929, p < 0.001; r = - 0.917, R2 = 0.841, p < 0.001) and after treatment in the blank seeds group (r = - 0.944, R2 = 0.891, p < 0.001). But after 125I seeds treatment there was no significant correlation between SUVmax and ADC (r = - 0.388, R2 = 0.151, p = 0.268).

CONCLUSION

The PET/CT and DW-MRI are capable of monitoring the early response of PDAC xenografts to brachytherapy. The significantly inverse correlation between pretreatment SUVmax and ADC suggests that PET/CT and DW-MRI might play complementary roles for therapy assessment.