[en] Purpose: Robotic stereotactic body radiation therapy (SBRT) for the treatment of hepatocellular carcinoma requires the peri-lesional implant of gold fiducial markers for detection by scopy. The purpose of this study is to determine whether the implant of gold fiducial markers is still possible and, if so, with which imaging technique and with what results. Materials and methods: This is a prospective study based on the implant of fiducial markers in the liver in our department for a treatment by SBRT for a hepatocellular carcinoma in 38 patients (49 lesions to treat) over a period of one year. As the first choice, it consisted of sonographic guidance and, if not possible, CT-scan guidance was used. Results: The mean number of fiducial markers implanted per procedure was 2.68(± 0.61) with almost exclusive sonographic guidance (36 out of 38 patients or 95% of the patients). The mean distance between the markers and the lesion was 32 mm (± 11 mm) and that between the markers was 17 mm (± 7 mm). Conclusion: SBRT is being evaluated for the treatment of liver lesions. The radiologist has an important role to play since the implant of fiducial markers in the liver is indispensable. It is almost always possible with sonographic guidance, including for lesions not accessible to micro-biopsies, a treatment by radiofrequency or for lesions poorly individualisable by sonography or CT-scan. (authors)

[en] Pain management of bone metastases is usually made using systemic and local therapy. Even though radiations are nowadays the gold standard for painful metastases, innovations regarding minimally invasive treatment approaches have been developed because of the existing non-responder patients [1]. Indeed, cementoplasty and thermo-ablations like radiofrequency or cryotherapy have shown to be efficient on pain [2-4]. Among thermo-therapy, magnetic resonance guided focalized ultrasound is now a new non-invasive weapon for bone pain palliation. (authors)

[en] Stereotactic radiotherapy has an increasing role in the treatment of inoperable patients suffering from early lung carcinomas. As response assessment remains difficult in some cases, and as it might be difficult to make the difference between response and growth, the authors discuss these issues, report a bibliographical review on lung stereotactic radiotherapy, comment the differences with conventional conformational radiotherapy. Modifications induced by stereotactic radiotherapy are limited to a restricted volume which surrounds the treated volume

[en] Purpose: PET with ⁶⁸Ga-DOTATOC allows for imaging and quantitative assessment of somatostatin receptor expression in neuroendocrine tumors (NET). The aim of this retrospective study was to analyze whether pre-therapeutic ⁶⁸Ga-DOTATOC PET/CT is able to predict response to Peptide Receptor Radionuclide Therapy (PRRT). Patients and methods: Forty patients with advanced stage NET were treated with a fixed dose of ⁹⁰Y-DOTATOC (5550 or 3700 MBq). Prior to PRRT, each patient received ⁶⁸Ga-DOTATOC PET/CT. Treatment results were evaluated after 3 months by CT, tumor marker levels and clinical course and correlated with ⁶⁸Ga-DOTATOC uptake (SUV_max) and the assumed uptake of ⁹⁰Y-DOTATOC in tumor manifestations (MBq/g). ROC analysis and pairwise comparison of area under the curve (AUC) were performed with pre-treatment uptake of ⁶⁸Ga-DOTATOC, assumed uptake of ⁹⁰Y-DOTATOC and treatment activity alone and in relation to body weight as continuous variables, and response/no response as classification variable. Results: According to conventional criteria (tumor shrinkage, decrease of tumor markers, improved or stable clinical condition), 20 patients were classified as responders, 16 as non-responders and in four patients findings were equivocal. Using a SUV more than 17.9 as cut-off for favorable outcome, PET was able to predict treatment response of all responders and 15 out of 16 non-responders. All four patients with equivocal findings showed SUV less than or equal to 17.9 and soon experienced tumor progression. The assumed uptake of ⁹⁰Y-DOTATOC in tumor manifestations using a cut-off more than 1.26 MBq/g as predictor of response was able to correctly classify 19 out of 20 responders, and 14 out of 16 non-responders. In all patients with equivocal findings, the assumed uptake of ⁹⁰Y-DOTATOC was below 1.26 MBq/g. Conclusion: Pre-therapeutic ⁶⁸Ga-DOTATOC tumor uptake as well as assumed uptake of ⁹⁰Y-DOTATOC are strongly associated with the results of subsequent PRRT. The defined cut-off values should be confirmed by prospective studies and may then provide the rationale for individual dosing and selecting patients with high likelihood of favorable treatment outcome. (authors)

[en] Interventional radiology is involved practically at each stage in the treatment of hepatocellular carcinoma, as recommended in the EASL-EORTC guidelines. It is even becoming more important as technological advances progress and as its long-term efficacy is assessed. Used curatively, thermo-ablation can obtain five-year survival rates of 40 to 70%, with a survival rate of 30% at 10 years. As there are many tools available in order to be used, it requires a thorough pre-treatment assessment and discussion in a multidisciplinary team meeting. Regular patient reassessment is needed in order to be able to adjust treatment because of the complementarity of the treatments available and the course of the disease. (authors)

[en] Targeted therapies have considerably improved the prognosis of patients with metastatic renal cancer (mRCC) but there are no reliable response assessment criteria reflecting the clinical benefits, because there is no regression in size, or it is delayed. Such criteria would help early identification of non-responders, who would then benefit from a change of treatment, and would avoid their being subjected to unnecessary side effects related to the treatment. We will review the imaging techniques currently available for evaluating tumour response in mRCC patients, including the response evaluation criteria in solid tumours (RECIST), the Choi criteria, the modified Choi criteria, and the CT size and attenuation criteria (SACT). We will also discuss functional imaging techniques, which are based on the physiological characteristics of the tumours, such as perfusion CT, magnetic resonance imaging or ultrasound (DCE-CT, DCE-MRI, DCE-US), diffusion MRI, BOLD MRI and new positron emission tomography (PET) tracers. It is not possible at present to propose a unanimously acknowledged criterion for evaluating tumour response to targeted therapy. However, there is a real need for this according to oncologists and the pharmaceutical industry, and radiologists need to be involved in reflecting on the subject. (authors)

[en] Radiation-induced lung disease (RILD) is frequent after therapeutic irradiation of thoracic malignancies. Many technique-, treatment-, tumor- and patient-related factors influence the degree of injury sustained by the lung after irradiation. Based on the time interval after the completion of the treatment RILD presents as early and late features characterized by inflammatory and fibrotic changes, respectively. They are usually confined to the radiation port. Though the typical pattern of RILD is easily recognized after conventional two-dimensional radiation therapy (RT), RILD may present with atypical patterns after more recent types of three or four-dimensional RT treatment. Three atypical patterns are reported: the modified conventional, the mass-like and the scar-like patterns. Knowledge of the various features and patterns of RILD is important for correct diagnosis and appropriate treatment. RILD should be differentiated from recurrent tumoral disease, infection and radiation-induced tumors. Due to RILD, the follow-up after RT may be difficult as response evaluation criteria in solid tumours (RECIST) criteria may be unreliable to assess tumor control particularly after stereotactic ablation RT (SABR). Long-term follow-up should be based on clinical examination and morphological and/or functional investigations including CT, PET-CT, pulmonary functional tests, MRI and PET-MRI. (authors)

[en] Exposure of the population to ionizing radiation for medical purposes is increasing throughout the world. In the United States of America, this exposure (3 mSv) has reached, even exceeded, exposure from natural sources. In France, the report of the French Institute for Radiological Protection and Nuclear Safety (IRSN) on exposure of the French population to ionizing radiation in 2007, based on the 74.6 million medical diagnostic procedures, estimates the mean individual effective dose to be 1.3 mSv. This value is much lower than the value in the United States but has progressed in 5 years by 62.5%. Computed tomography accounts for 10.1% of the procedures and 58% of the collective effective dose. This is why computed tomography is receiving very special attention from all those involved in radioprotection. It must be remembered, nevertheless, that we are well within the low dose range (effective dose less than 100 mSv), and indeed, in the large majority of CT examinations exposure values are lower than 15 mSv. The biological effects of low doses are still a matter of debate. First of all, it has not been possible to demonstrate the risk of cancer due to this level of exposure, neither on the survivors of the atomic bombs in Japan nor on workers in the nuclear industry in the United Kingdom. The year 2012 marked a change; for the first time, epidemiology took over from statistical studies. Despite the low risk demonstrated, reserves concerning methodology, and waiting for further European epidemiological studies underway, we must continue to act to encourage radiological protection. Before considering the action to take and without under-estimating the risks, it is important to remember that a computed tomography investigation is conducted in patients, and not in individuals in good health. Acting to provide patients with protection from radiation means involving all those concerned with justifying it, with substituting it, and with optimising it. For some years manufacturers have been developing technological innovations to reduce the dose, including control of automatic exposure, automatic selection of the most suitable voltage, appropriate filters, dynamic collimation in the Z-axis, iterative reconstruction, and techniques for reducing noise. Other innovations are underway focusing particularly on detector technology. The objective is to be able to undertake CT investigations with an effective dose lower than 1 mSv. If this objective is achieved in the next few years, progress will be considerable. We need to be able to renew our stock of scanners regularly so that our patients can reap the benefit. Clearly we are responsible each day for justifying the procedures. Substitution by non-irradiating procedures depends both on us and on the public authorities. Optimisation is also essential, and in the first instance will be achieved by abandoning the worship of a pretty picture. We have to set our minds on the objective of producing a diagnostic image with the lowest dose possible. It is the job of our profession to promote the spread of good practice guides and also encourage all teams to embark on optimising their protocols. In the end, we must all continue to keep ourselves informed and take part in assessing our practices

[en] With an improvement in the temporal and spatial resolution, computed tomography (CT) is indicated in the evaluation of a great many osteo-articular diseases. New exploration techniques such as the dynamic CT and CT bone perfusion also provide new indications. However, CT is still an irradiating imaging technique and dose optimisation and reduction remains primordial. In this paper, the authors first present the typical doses delivered during CT in osteo-articular disease. They then discuss the different ways to optimise and reduce these doses by distinguishing the behavioural factors from the technical factors. Among the latter, the optimisation of the milli-amps and kilo-voltage is indispensable and should be adapted to the type of exploration and the morpho-type of each individual. These technical factors also benefit from recent technological evolutions with the distribution of iterative reconstructions. In this way, the dose may be divided by two and provide an image of equal quality. With these dose optimisation and reduction techniques, it is now possible, while maintaining an excellent quality of the image, to obtain low-dose or even very low-dose acquisitions with a dose sometimes similar that of a standard X-ray assessment. Nevertheless, although these technical factors provide a major reduction in the dose delivered, behavioural factors, such as compliance with the indications, remain fundamental. Finally, the authors describe how to optimise and reduce the dose with specific applications in musculoskeletal imaging such as the dynamic CT, CT bone perfusion and dual energy CT. (authors)

[en] Detecting a new area of contrast-enhancement at MRI after irradiation of malignant brain tumor arises the problem of differential diagnosis between tumor recurrence and radiation necrosis induced by the treatment. The challenge for imaging is to distinguish the two diagnoses given: the prognostic and therapeutic issues. Various criteria have been proposed in the literature based on morphological, functional or metabolic MRI. The purpose of this study was to perform an analysis of these tools to identify MRI best criteria to differentiate radiation necrosis lesions from malignant gliomas and brain metastases recurrence. For gliomas, the morphology of the contrast-enhancement cannot guide the diagnosis and the use of perfusion techniques and spectroscopy (multi-voxels if possible) are necessary. In the follow-up of metastasis, a transient increase and moderate lesion volume is possible with a good prognosis. Morphological characteristics (volume ratio T2/T1Gd) and perfusion analysis provide valuable tools for approaching the diagnosis of radionecrosis. (authors)