Response Evaluation in Head and Neck Oncology: Definition and Prediction.

Curative treatment of head and neck squamous cell carcinoma includes surgery and/or (chemo)radiation, whereas in the palliative setting, chemotherapy and/or immunotherapy represent(s) the standard approach. With regard to quality control, methods for determining treatment response are sorely needed. For surgical therapy, histopathology is the standard quality control. Established criteria for high-risk patients include resection margins of the primary tumor and extracapsular extension of lymph node metastases. After definitive chemoradiation, treatment response is generally evaluated by tomographic imaging combined with endoscopy including re-biopsy of the tumor region. Single-cycle induction chemotherapy may be used to determine the radiosensitivity of tumors, helping to define surgical and nonsurgical treatment options. Innovative approaches with implications for prognosis include the analysis of immune infiltrates, liquid biopsy, molecular characterization (proteomics, genomics), molecular and functional imaging (PET-CT, PET-MRI), as well as advanced imaging data analysis (radio[geno]mics/texture analysis). Human papilloma virus, as a prognostically relevant parameter, is currently being investigated for de-escalation strategies. With regard to the extended personalization of oncologic therapy, markers predicting treatment response are desirable and seem to be important, also from a socioeconomic perspective.

Bone mineral density measurements of the proximal femur from routine contrast-enhanced MDCT data sets correlate with dual-energy X-ray absorptiometry.

OBJECTIVES: To evaluate the utility of femoral bone mineral density (BMD) measurements in routine contrast-enhanced multi-detector computed tomography (ceMDCT) using dual-energy X-ray absorptiometry (DXA) as the reference standard. METHODS: Forty-one patients (33 women, 8 men) underwent DXA measurement of the proximal femur. Subsequently, transverse sections of routine ceMDCT of these patients were used to measure BMD of the femoral head and femoral neck. The MDCT-to-DXA conversion equations for BMD and T-score were calculated using linear regression analysis. The conversion equations were applied to the MDCT data sets of 382 patients (120 women, 262 men) of whom 74 had osteoporotic fractures. RESULTS: A correlation coefficient of r = 0.84 (P < 0.05) was calculated for BMD(MDCT) values of the femoral head and DXA T-scores of the total proximal femur using the conversion equation T-score = 0.021 × BMD(MDCT) - 5.90. The correlation coefficient for the femoral neck was r = 0.79 (P < 0.05) with the conversion equation T-score = 0.016 × BMD(MDCT) - 4.28. Accordingly, converted T-scores for the femoral neck in patients with versus those without osteoporotic fractures were significantly different (female, -1.83 versus -1.47; male, -1.86 versus -1.47; P < 0.05). CONCLUSION: BMD measurements of the proximal femur were computed in routine contrast-enhanced MDCT and converted to DXA T-scores, which adequately differentiated patients with and without osteoporotic fractures.

Radiolabelled RGD peptides for imaging and therapy.

Imaging of angiogenesis has become increasingly important with the rising use of targeted antiangiogenic therapies like bevacizumab (Avastin). Non-invasive assessment of angiogenic activity is in this respect interesting, e.g. for response assessment of such targeted antiangiogenic therapies. One promising approach of angiogenesis imaging is imaging of specific molecular markers of the angiogenic cascade like the integrin α(v)ß(3). For molecular imaging of integrin expression, the use of radiolabelled peptides is still the only approach that has been successfully translated into the clinic. In this review we will summarize the current data on imaging of α(v)ß(3) expression using radiolabelled RGD peptides with a focus on tracers already in clinical use. A perspective will be presented on the future clinical use of radiolabelled RGD peptides including an outlook on potential applications for radionuclide therapy.

Comparison of 3'-deoxy-3'-[¹8F]fluorothymidine positron emission tomography (FLT PET) and FDG PET/CT for the detection and characterization of pancreatic tumours.

PURPOSE: Despite recent advances in clinical imaging modalities, differentiation of pancreatic masses remains difficult. Here, we tested the diagnostic accuracy of molecular-based imaging including 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) positron emission tomography (PET) and [(18)F]fluorodeoxyglucose (FDG) PET/CT in patients with suspected pancreatic masses scheduled to undergo surgery. METHODS: A total of 46 patients with pancreatic tumours suspicious for malignancy and scheduled for resective surgery were recruited prospectively. In 41 patients, FLT PET and FDG PET/CT scans were performed. A diagnostic CT performed on a routine basis was available in 31 patients. FLT PET and FDG PET/CT emission images were acquired according to standard protocols. Tracer uptake in the tumour [FDG and FLT standardized uptake value (SUV)] was quantified by the region of interest (ROI) technique. For FDG PET/CT analysis, correct ROI placement was ensured via side-by-side reading of corresponding CT images. RESULTS: Of 41 patients, 33 had malignancy, whereas 8 patients had benign disease. Visual analysis of FDG and FLT PET resulted in sensitivity values of 91% (30/33) and 70% (23/33), respectively. Corresponding specificities were 50% (4/8) for FDG PET and 75% (6/8) for FLT PET. In the subgroup of patients with contrast-enhanced CT (n = 31), sensitivities were 96% (PET/CT), 88% (CT alone), 92% (FDG PET) and 72% (FLT PET), respectively. Mean FLT uptake in all malignant tumours was 3.0 (range SUV(max) 1.1-6.5; mean FDG SUV(max) 7.9, range 3.3-17.8; p < 0.001). CONCLUSION: For differentiation of pancreatic tumours, FDG PET and FDG PET/CT showed a higher sensitivity but lower specificity than FLT PET. Interestingly, visual analysis of FLT PET led to two false-positive findings by misinterpreting physiological bowel uptake as pathological FLT uptake in the pancreas. Due to the limited number of patients, the clinical value of adding FLT PET to the diagnostic workup of pancreatic tumours remains to be determined.

Molecular imaging of avb3 expression in cancer patients.

Angiogenesis, the formation of new blood vessels, is a key process in the growth of solid tumors. Thus this process could potentially be utilized for diagnosis of malignancies by molecular imaging on the one hand and for tumor treatment on the other hand. Imaging of angiogenesis has become increasingly important with the rising use of targeted antiangiogenic therapies, like bevacizumab (Avastin). Non-invasive assessment of angiogenic activity is in this respect interesting e.g. for response assessment of such targeted antiangiogenic therapies. Several methods have been employed for imaging of angiogenesis in vivo. Mostly these approaches measure physical parameters of the tissue, e.g. blood flow, blood volume and vessel permeability. Another approach of angiogenesis imaging is imaging of specific molecular markers of the angiogenic cascade. Integrins, like avb3, but also avb5 and a5b1, play a central role in the angiogenic process and integrin avb3 binding substances can be used as imaging probes to assess integrin expression. For clinical applications, the use of radiolabeled integrin binding substances is favorable, as radiotracers can be detected with very high sensitivities in vivo. As the radiotracer approach for molecular imaging of avb3 expression is by now the only approach used in the clinical setting, it will be the focus of this review. We will summarize the current data on imaging of avb3 expression in the clinical arena using single photon emission computed tomography (SPECT) and positron emission tomography (PET). Moreover, an outlook will be presented on potential clinical applications of imaging of avb3 expression.

Multimodal tumor therapy in a 31-year-old pregnant woman with Wilms tumor.

Wilms tumor, or nephroblastoma, is the most common malignant tumor of the urinary tract in children, but is rarely found in adults. Here, we report the first case of a female patient with a Wilms tumor, diagnosed during pregnancy, who underwent radical nephrectomy and adjuvant chemotherapy before and after delivering a healthy child. Generally, treatment should follow the guidelines established for the pediatric setting.

[The role of the vesical imaging-reporting and data system (VI-RADS) for bladder cancer diagnostics-status quo]. / Bedeutung der VI-RADS-Klassifikation für die Bildgebung beim Harnblasenkarzinom ­ Stand der Dinge.

Initial clinical and pathological diagnostic workup of urinary bladder cancer is based on cystoscopy, transurethral resection of suspicious lesions, and computed tomography when indicated. Accurate staging is necessary for further therapeutic decision-making. This review summarizes the current status of multiparametric magnetic resonance imaging (mpMRI) and the vesical imaging-reporting and data system (VI-RADS) classification. MpMRI may improve the accuracy of assessment of local tumor invasion compared to conventional imaging alone. VI-RADS standardizes reporting of MRI staging and classifies the likelihood of muscle-invasive bladder cancer into five categories. Preliminary data suggest low interobserver variability. However, prospective multicenter studies are necessary to validate the VI-RADS classification. Progress in functional, molecular, and hybrid imaging may further improve the accuracy of clinical tumor and nodal staging for bladder cancer.

Apparent Diffusion Coefficient (ADC) predicts therapy response in pancreatic ductal adenocarcinoma.

Recent advances in molecular subtyping of Pancreatic Ductal Adenocarcinoma (PDAC) support individualization of therapeutic strategies in this most aggressive disease. With the emergence of various novel therapeutic strategies and neoadjuvant approaches in this quickly deteriorating disease, robust approaches for fast evaluation of therapy response are urgently needed. To this aim, we designed a preclinical imaging-guided therapy trial where genetically engineered mice harboring endogenous aggressive PDAC were treated with the MEK targeting drug refametinib, which induces rapid and profound tumor regression in this model system. Multi-parametric non-invasive imaging was used for therapy response monitoring. A significant increase in the Diffusion-Weighted Magnetic Resonance Imaging derived Apparent Diffusion Coefficient (ADC) was noted already 24 hours after treatment onset. Histopathological analyses showed increased apoptosis and matrix remodeling at this time point. Our findings suggest the ADC parameter as an early predictor of therapy response in PDAC.

Combined PET/MRI: from Status Quo to Status Go. Summary Report of the Fifth International Workshop on PET/MR Imaging; February 15-19, 2016; Tübingen, Germany.

This article provides a collaborative perspective of the discussions and conclusions from the fifth international workshop of combined positron emission tomorgraphy (PET)/magnetic resonance imaging (MRI) that was held in Tübingen, Germany, from February 15 to 19, 2016. Specifically, we summarise the second part of the workshop made up of invited presentations from active researchers in the field of PET/MRI and associated fields augmented by round table discussions and dialogue boards with specific topics. This year, this included practical advice as to possible approaches to moving PET/MRI into clinical routine, the use of PET/MRI in brain receptor imaging, in assessing cardiovascular diseases, cancer, infection, and inflammatory diseases. To address perceived challenges still remaining to innovatively integrate PET and MRI system technologies, a dedicated round table session brought together key representatives from industry and academia who were engaged with either the conceptualisation or early adoption of hybrid PET/MRI systems. Discussions during the workshop highlighted that emerging unique applications of PET/MRI such as the ability to provide multi-parametric quantitative and visual information which will enable not only overall disease detection but also disease characterisation would eventually be regarded as compelling arguments for the adoption of PET/MR. However, as indicated by previous workshops, evidence in favour of this observation is only growing slowly, mainly due to the ongoing inability to pool data cohorts from independent trials as well as different systems and sites. The participants emphasised that moving from status quo to status go entails the need to adopt standardised imaging procedures and the readiness to act together prospectively across multiple PET/MRI sites and vendors.

Combined PET/MRI: Multi-modality Multi-parametric Imaging Is Here: Summary Report of the 4th International Workshop on PET/MR Imaging; February 23-27, 2015, Tübingen, Germany.

This paper summarises key themes and discussions from the 4th international workshop dedicated to the advancement of the technical, scientific and clinical applications of combined positron emission tomography (PET)/magnetic resonance imaging (MRI) systems that was held in Tübingen, Germany, from February 23 to 27, 2015. Specifically, we summarise the three days of invited presentations from active researchers in this and associated fields augmented by round table discussions and dialogue boards with specific topics. These include the use of PET/MRI in cardiovascular disease, paediatrics, oncology, neurology and multi-parametric imaging, the latter of which was suggested as a key promoting factor for the wider adoption of integrated PET/MRI. Discussions throughout the workshop and a poll taken on the final day demonstrated that attendees felt more strongly that PET/MRI has further advanced in both technical versatility and acceptance by clinical and research-driven users from the status quo of last year. Still, with only minimal evidence of progress made in exploiting the true complementary nature of the PET and MRI-based information, PET/MRI is still yet to achieve its potential. In that regard, the conclusion of last year's meeting "the real work has just started" still holds true.

Combined PET/MR: The Real Work Has Just Started. Summary Report of the Third International Workshop on PET/MR Imaging; February 17-21, 2014, Tübingen, Germany.

This paper summarises the proceedings and discussions at the third annual workshop held in Tübingen, Germany, dedicated to the advancement of the technical, scientific and clinical applications of combined PET/MRI systems in humans. Two days of basic scientific and technical instructions with "hands-on" tutorials were followed by 3 days of invited presentations from active researchers in this and associated fields augmented by round-table discussions and dialogue boards with specific themes. These included the use of PET/MRI in paediatric oncology and in adult neurology, oncology and cardiology, the development of multi-parametric analyses, and efforts to standardise PET/MRI examinations to allow pooling of data for evaluating the technology. A poll taken on the final day demonstrated that over 50 % of those present felt that while PET/MRI technology underwent an inevitable slump after its much-anticipated initial launch, it was now entering a period of slow, progressive development, with new key applications emerging. In particular, researchers are focusing on exploiting the complementary nature of the physiological (PET) and biochemical (MRI/MRS) data within the morphological framework (MRI) that these devices can provide. Much of the discussion was summed up on the final day when one speaker commented on the state of PET/MRI: "the real work has just started".

Development of serotonin-like and SALMFamide-like immunoreactivity in the nervous system of the sea urchin Psammechinus miliaris.

The present immunocytochemical study utilizes serotonin and SALMFamide antisera, together with confocal laser scanning microscopy, to provide new information about the development of the nervous system in the sea urchin Psammechinus miliaris (Echinodermata: Echinoidea). Special attention is paid to the extent of the nervous system in later larval stages (6-armed pluteus to metamorphic competency), a characteristic that has not been well described in this and other species of sea urchin. An extensive apical ganglion appears by the 6-armed pluteus stage, forming a complex of 10-20 cells and fibers, including discrete populations of both serotonin-like and SALMF-amide-like immunoreactive cells. At metamorphosis this complex is large, comprising at least 40 cells in distinct arrays. Serotonin-like immunoreactivity is also particularly apparent in the lower lip ganglion of 6- to 8-armed plutei; this ganglion consists of 15-18 cells that are distributed around the mouth. The ciliary nerves that lie beneath the ciliary bands in the larval arms, the esophagus, and a hitherto undescribed network associated with the pylorus all show SALMFamide-like immunoreactivity. The network of cells and fibers in the pyloric area develops later in larval life. It first appears as one cell body and fiber, then increases in size and complexity through the 8-armed pluteus stage to form a complex of cells that encircles the pylorus. SALMFamide-like, but not serotonin-like, immunoreactivity is seen in the vestibule wall, tube feet, and developing radial nerve fibers of the sea urchin adult rudiment as the larva gains metamorphic competency.

[Functional imaging in bladder cancer]. / Funktionelle Bildgebung beim Harnblasenkarzinom.

Computed tomography (CT) represents the current standard imaging modality in muscle invasive bladder cancer; however, local tumor and lymph node staging is often impaired. Magnetic resonance imaging (MRI) with diffusion-weighted sequences, determination of apparent diffusion coefficient (ADC) values or utilization of supraparamagnetic iron nanoparticles potentially exhibits advantages in the assessment of local tumor and lymph node involvement and therefore might play a role in the staging of bladder tumor in the future. Likewise, positron emission tomography (PET) with the currently used tracers (18)F fluorodeoxyglucose ((18)F-FDG), (11)C-choline and (11)C-acetate is being investigated in bladder cancer patients, mostly in combination with diagnostic CT. Although promising results could be obtained for PET/CT investigations to some extent, the true value cannot be determined at present.

Imaging of hypoxia using PET and MRI.

Tumor hypoxia is the result of an inadequate supply of oxygen to tumor cells which can be caused by multiple factors. It is associated with aggressive local tumor growth and invasion, increased risk of metastasis, higher resistance to radiotherapy (RT) and chemotherapy, overall resulting in a poor clinical prognosis. Many locally advanced solid tumors may exhibit hypoxic and/or anoxic tissue areas that are heterogeneously distributed within the tumor mass. As hypoxia is a negative prognostic factor concerning response to radiotherapy and chemotherapy, in vivo measurement of tumor hypoxia could be helpful to identify patients with worse prognosis or patients that could benefit from appropriate treatments such as intensity modulated radiotherapy (IMRT) that may accurately conform the dose distribution to small intratumoral regions showing differences in the oxygen level. A manifold of different methods to assess the oxygen tension (pO2) in tissues have been developed, each of them offering advantages as well as drawbacks. They range from invasive direct measurement techniques of the pO2 in tissue by using a polarographic electrode, to non-invasive imaging techniques such as positron emission tomography (PET) or magnetic resonance imaging (MRI). This article provides an overview over the various methods, with a particular emphasis on PET and MRI for imaging of hypoxia, and reviews their performance in preclinical and clinical studies.

Inversion-recovery single-shot cardiac MRI for the assessment of myocardial infarction at 1.5 T with a dedicated cardiac coil.

OBJECTIVE: The aim of this study was to assess the diagnostic accuracy of imaging myocardial infarction with a two-dimensional (2D) single-shot inversion-recovery (IR)-gradient-echo (GE) sequence compared with a standard 2D segmented IR-GE sequence at 1.5 T using a dedicated cardiac coil. METHODS: 22 patients with myocardial infarction documented in the past 3-12 months were examined at 1.5 T using a 5 channel cardiac coil. Imaging of delayed enhancement was performed 15 min after administration of 0.2 mmol of gadopentetate dimeglumine per kilogram of body weight. Immediately after completion of the single-shot sequence, which allows for coverage of the entire ventricle during a single breath-hold with nine slices, the segmented IR sequence was started. Infarct volumes, infarct transmurality and contrast-to-noise ratios (CNRs) of infarcted and healthy myocardium were compared between both techniques. RESULTS: Despite a moderate, non-significant loss of CNR (CNR(single-shot IR)=31.2±4.1; CNR(segmented IR)=37.9±4.1; p=0.405), the 2D single-shot technique correctly determined infarct size when compared with the standard 2D segmented IR-GE sequence. Assessment of both infarct volume (r=0.95; p<0.0001) and transmurality (r=0.97; p<0.0001) is possible, with excellent correlation of both techniques. CONCLUSION: Single-shot delayed enhancement imaging during a single breath-hold is feasible at 1.5 T with the use of a dedicated cardiac coil. Despite a moderately lower CNR, the single-shot technique allows for fast and accurate determination of infarct size with high spatial resolution and has the potential to reduce electrocardiogram and breathing artefacts.

Molecular imaging of αvß3 expression in cancer patients.

Angiogenesis, the formation of new blood vessels, is a key process in the growth of solid tumors. Thus this process could potentially be utilized for diagnosis of malignancies by molecular imaging on the one hand and for tumor treatment on the other hand. Imaging of angiogenesis has become increasingly important with the rising use of targeted antiangiogenic therapies, like bevacizumab (Avastin). Non-invasive assessment of angiogenic activity is in this respect interesting e.g. for response assessment of such targeted antiangiogenic therapies. Several methods have been employed for imaging of angiogenesis in vivo. Mostly these approaches measure physical parameters of the tissue, e.g. blood flow, blood volume and vessel permeability. Another approach of angiogenesis imaging is imaging of specific molecular markers of the angiogenic cascade. Integrins, like αvß3, but also αvß5 and α5ß1, play a central role in the angiogenic process and integrin αvß3 binding substances can be used as imaging probes to assess integrin expression. For clinical applications, the use of radiolabeled integrin binding substances is favorable, as radiotracers can be detected with very high sensitivities in vivo. As the radiotracer approach for molecular imaging of αvß3 expression is by now the only approach used in the clinical setting, it will be the focus of this review. We will summarize the current data on imaging of αvß3 expression in the clinical arena using single photon emission computed tomography (SPECT) and positron emission tomography (PET). Moreover, an outlook will be presented on potential clinical applications of imaging of αvß3 expression.

[Molecular imaging with new PET tracers]. / Molekulare Bildgebung mit neuen PET-Tracern.

In the recent years, positron emission tomography (PET) has gained more and more importance, especially in oncology for primary staging, as well as for response evaluation. The glucose analogon (18)F-FDG is the most widely used tracer up to now. In this paper, we review the applications of newly developed, more specific PET tracers. These tracers allow for imaging of a variety of biological processes, such as hypoxia and proliferation. The expression of different receptors can be visualized, like the somatostatin receptor 2 and the integrin alphavbeta3. Moreover, gene expression can be imaged as well. While most of these approaches are currently in the first phases of clinical evaluation, imaging of hypoxia and proliferation might be integrated into the daily routine in the near future.

[MSCT for staging and response evaluation of esophageal cancer]. / Staging und Therapiebeurteilung des Osophaguskarzinoms mittels MSCT.

Squamous cell carcinomas and adenocarcinomas account for the majority of cases of esophageal cancer. Esophageal cancer often is diagnosed in advanced stages as clinical symptoms are lacking in early stages. The major aims of imaging in esophageal cancer are to determine local tumor extension (T and N staging), to rule out systemic disease (M staging), and to assess response to neoadjuvant therapy (response evaluation). CT is still inferior to endoscopic ultrasound in differentiating T stages and detecting regional lymph node metastases. However, it plays a central role in determining infiltration into adjacent organs (T4 stage) and in ruling out distant metastases. Multislice-CT (MSCT) offers the possibility of reconstructions, which often help to assess the relationship between tumor and anatomic landmarks like the tracheobronchial tree or the diaphragm. First results of CT volumetry for response evaluation are promising; however, PET and PET/CT with the glucose analogue FDG are the standard methods to evaluate response to neoadjuvant therapy.