Using the gamma-index analysis for inter-fractional comparison of in-beam PET images for head-and-neck treatment monitoring in proton therapy: A Monte Carlo simulation study

GOAL

In-beam Positron Emission Tomography (PET) is a technique for in-vivo non-invasive treatment monitoring for proton therapy. To detect anatomical changes in patients with PET, various analysis methods exist, but their clinical interpretation is problematic. The goal of this work is to investigate whether the gamma-index analysis, widely used for dose comparisons, is an appropriate tool for comparing in-beam PET distributions. Focusing on a head-and-neck patient, we investigate whether the gamma-index map and the passing rate are sensitive to progressive anatomical changes.

METHODS/MATERIALS

We simulated a treatment course of a proton therapy patient using FLUKA Monte Carlo simulations. Gradual emptying of the sinonasal cavity was modeled through a series of artificially modified CT scans. The in-beam PET activity distributions from three fields were evaluated, simulating a planar dual head geometry. We applied the 3D-gamma evaluation method to compare the PET images with a reference image without changes. Various tolerance criteria and parameters were tested, and results were compared to the CT-scans.

RESULTS

Based on 210 MC simulations we identified appropriate parameters for the gamma-index analysis. Tolerance values of 3 mm/3% and 2 mm/2% were suited for comparison of simulated in-beam PET distributions. The gamma passing rate decreased with increasing volume change for all fields.

CONCLUSION

The gamma-index analysis was found to be a useful tool for comparing simulated in-beam PET images, sensitive to sinonasal cavity emptying. Monitoring the gamma passing rate behavior over the treatment course is useful to detect anatomical changes occurring during the treatment course.

Synthetic CT imaging for PET monitoring in proton therapy: a simulation study

Objective.This study addresses a fundamental limitation of in-beam positron emission tomography (IB-PET) in proton therapy: the lack of direct anatomical representation in the images it produces. We aim to overcome this shortcoming by pioneering the application of deep learning techniques to create synthetic control CT images (sCT) from combining IB-PET and planning CT scan data.Approach.We conducted simulations involving six patients who underwent irradiation with proton beams. Leveraging the architecture of a visual transformer (ViT) neural network, we developed a model to generate sCT images of these patients using the planning CT scans and the inter-fractional simulated PET activity maps during irradiation. To evaluate the model's performance, a comparison was conducted between the sCT images produced by the ViT model and the authentic control CT images-serving as the benchmark.Main results.The structural similarity index was computed at a mean value across all patients of 0.91, while the mean absolute error measured 22 Hounsfield Units (HU). Root mean squared error and peak signal-to-noise ratio values were 56 HU and 30 dB, respectively. The Dice similarity coefficient exhibited a value of 0.98. These values are comparable to or exceed those found in the literature. More than 70% of the synthetic morphological changes were found to be geometrically compatible with the ones reported in the real control CT scan.Significance.Our study presents an innovative approach to surface the hidden anatomical information of IB-PET in proton therapy. Our ViT-based model successfully generates sCT images from inter-fractional PET data and planning CT scans. Our model's performance stands on par with existing models relying on input from cone beam CT or magnetic resonance imaging, which contain more anatomical information than activity maps.

Expansion and Light-Sheet Microscopy for Nanoscale 3D Imaging

Expansion Microscopy (ExM) and Light-Sheet Fluorescence Microscopy (LSFM) are forefront imaging techniques that enable high-resolution visualization of biological specimens. ExM enhances nanoscale investigation using conventional fluorescence microscopes, while LSFM offers rapid, minimally invasive imaging over large volumes. This review explores the joint advancements of ExM and LSFM, focusing on the excellent performance of the integrated modality obtained from the combination of the two, which is refer to as ExLSFM. In doing so, the chemical processes required for ExM, the tailored optical setup of LSFM for examining expanded samples, and the adjustments in sample preparation for accurate data collection are emphasized. It is delve into various specimen types studied using this integrated method and assess its potential for future applications. The goal of this literature review is to enrich the comprehension of ExM and LSFM, encouraging their wider use and ongoing development, looking forward to the upcoming challenges, and anticipating innovations in these imaging techniques.

Walk-through flat panel total-body PET: a patient-centered design for high throughput imaging at lower cost using DOI-capable high-resolution monolithic detectors

PURPOSE

Long axial field-of-view (LAFOV) systems have a much higher sensitivity than standard axial field-of-view (SAFOV) PET systems for imaging the torso or full body, which allows faster and/or lower dose imaging. Despite its very high sensitivity, current total-body PET (TB-PET) throughput is limited by patient handling (positioning on the bed) and often a shortage of available personnel. This factor, combined with high system costs, makes it hard to justify the implementation of these systems for many academic and nearly all routine nuclear medicine departments. We, therefore, propose a novel, cost-effective, dual flat panel TB-PET system for patients in upright standing positions to avoid the time-consuming positioning on a PET-CT table; the walk-through (WT) TB-PET. We describe a patient-centered, flat panel PET design that offers very efficient patient throughput and uses monolithic detectors (with BGO or LYSO) with depth-of-interaction (DOI) capabilities and high intrinsic spatial resolution. We compare system sensitivity, component costs, and patient throughput of the proposed WT-TB-PET to a SAFOV (= 26 cm) and a LAFOV (= 106 cm) LSO PET systems.

METHODS

Patient width, height (= top head to start of thighs) and depth (= distance from the bed to front of patient) were derived from 40 randomly selected PET-CT scans to define the design dimensions of the WT-TB-PET. We compare this new PET system to the commercially available Siemens Biograph Vision 600 (SAFOV) and Siemens Quadra (LAFOV) PET-CT in terms of component costs, system sensitivity, and patient throughput. System cost comparison was based on estimating the cost of the two main components in the PET system (Silicon Photomultipliers (SiPMs) and scintillators). Sensitivity values were determined using Gate Monte Carlo simulations. Patient throughput times (including CT and scout scan, patient positioning on bed and transfer) were recorded for 1 day on a Siemens Vision 600 PET. These timing values were then used to estimate the expected patient throughput (assuming an equal patient radiotracer injected activity to patients and considering differences in system sensitivity and time-of-flight information) for WT-TB-PET, SAFOV and LAFOV PET.

RESULTS

The WT-TB-PET is composed of two flat panels; each is 70 cm wide and 106 cm high, with a 50-cm gap between both panels. These design dimensions were justified by the patient sizes measured from the 40 random PET-CT scans. Each panel consists of 14 × 20 monolithic BGO detector blocks that are 50 × 50 × 16 mm in size and are coupled to a readout with 6 × 6 mm SiPMs arrays. For the WT-TB-PET, the detector surface is reduced by a factor of 1.9 and the scintillator volume by a factor of 2.2 compared to LAFOV PET systems, while demonstrating comparable sensitivity and much better uniform spatial resolution (< 2 mm in all directions over the FOV). The estimated component cost for the WT-TB-PET is 3.3 × lower than that of a 106 cm LAFOV system and only 20% higher than the PET component costs of a SAFOV. The estimated maximum number of patients scanned on a standard 8-h working day increases from 28 (for SAFOV) to 53-60 (for LAFOV in limited/full acceptance) to 87 (for the WT-TB-PET). By scanning faster (more patients), the amount of ordered activity per patient can be reduced drastically: the WT-TB-PET requires 66% less ordered activity per patient than a SAFOV.

CONCLUSIONS

We propose a monolithic BGO or LYSO-based WT-TB-PET system with DOI measurements that departs from the classical patient positioning on a table and allows patients to stand upright between two flat panels. The WT-TB-PET system provides a solution to achieve a much lower cost TB-PET approaching the cost of a SAFOV system. High patient throughput is increased by fast patient positioning between two vertical flat panel detectors of high sensitivity. High spatial resolution (< 2 mm) uniform over the FOV is obtained by using DOI-capable monolithic scintillators.

In-vivo range verification analysis with in-beam PET data for patients treated with proton therapy at CNAO

Morphological changes that may arise through a treatment course are probably one of the most significant sources of range uncertainty in proton therapy. Non-invasive in-vivo treatment monitoring is useful to increase treatment quality. The INSIDE in-beam Positron Emission Tomography (PET) scanner performs in-vivo range monitoring in proton and carbon therapy treatments at the National Center of Oncological Hadrontherapy (CNAO). It is currently in a clinical trial (ID: NCT03662373) and has acquired in-beam PET data during the treatment of various patients. In this work we analyze the in-beam PET (IB-PET) data of eight patients treated with proton therapy at CNAO. The goal of the analysis is twofold. First, we assess the level of experimental fluctuations in inter-fractional range differences (sensitivity) of the INSIDE PET system by studying patients without morphological changes. Second, we use the obtained results to see whether we can observe anomalously large range variations in patients where morphological changes have occurred. The sensitivity of the INSIDE IB-PET scanner was quantified as the standard deviation of the range difference distributions observed for six patients that did not show morphological changes. Inter-fractional range variations with respect to a reference distribution were estimated using the Most-Likely-Shift (MLS) method. To establish the efficacy of this method, we made a comparison with the Beam’s Eye View (BEV) method. For patients showing no morphological changes in the control CT the average range variation standard deviation was found to be 2.5 mm with the MLS method and 2.3 mm with the BEV method. On the other hand, for patients where some small anatomical changes occurred, we found larger standard deviation values. In these patients we evaluated where anomalous range differences were found and compared them with the CT. We found that the identified regions were mostly in agreement with the morphological changes seen in the CT scan.

A neural network-based algorithm for simultaneous event positioning and timestamping in monolithic scintillators

Objective. Monolithic scintillator crystals coupled to silicon photomultiplier (SiPM) arrays are promising detectors for PET applications, offering spatial resolution around 1 mm and depth-of-interaction information. However, their timing resolution has always been inferior to that of pixellated crystals, while the best results on spatial resolution have been obtained with algorithms that cannot operate in real-time in a PET detector. In this study, we explore the capabilities of monolithic crystals with respect to spatial and timing resolution, presenting new algorithms that overcome the mentioned problems. Approach. Our algorithms were tested first using a simulation framework, then on experimentally acquired data. We tested an event timestamping algorithm based on neural networks which was then integrated into a second neural network for simultaneous estimation of the event position and timestamp. Both algorithms are implemented in a low-cost field-programmable gate array that can be integrated in the detector and can process more than 1 million events per second in real-time. Results. Testing the neural network for the simultaneous estimation of the event position and timestamp on experimental data we obtain 0.78 2D FWHM on the (x, y) plane, 1.2 depth-of-interaction FWHM and 156 coincidence time resolution on a 25 mm × 25 mm × 8 mm × LYSO monolith read-out by 64 3 mm × 3 mm Hamamatsu SiPMs. Significance. Our results show that monolithic crystals combined with artificial intelligence can rival pixellated crystals performance for time-of-flight PET applications, while having better spatial resolution and DOI resolution. Thanks to the use of very light neural networks, event characterization can be done on-line directly in the detector, solving the issues of scalability and computational complexity that up to now were preventing the use of monolithic crystals in clinical PET scanners.

Performance evaluation of the IRIS XL-220 PET/CT system, a new camera dedicated to non-human primates

BACKGROUND

Non-human primates (NHP) are critical in biomedical research to better understand the pathophysiology of diseases and develop new therapies. Based on its translational and longitudinal abilities along with its non-invasiveness, PET/CT systems dedicated to non-human primates can play an important role for future discoveries in medical research. The aim of this study was to evaluate the performance of a new PET/CT system dedicated to NHP imaging, the IRIS XL-220 developed by Inviscan SAS. This was performed based on the National Electrical Manufacturers Association (NEMA) NU 4-2008 standard recommendations (NEMA) to characterize the spatial resolution, the scatter fraction, the sensitivity, the count rate, and the image quality of the system. Besides, the system was evaluated in real conditions with two NHP with ¹⁸F-FDG and (-)-[¹⁸F]FEOBV which targets the vesicular acetylcholine transporter, and one rat using ¹⁸F-FDG.

RESULTS

The full width at half maximum obtained with the 3D OSEM algorithm ranged between 0.89 and 2.11 mm in the field of view. Maximum sensitivity in the 400-620 keV and 250-750 keV energy windows were 2.37% (22 cps/kBq) and 2.81% (25 cps/kBq), respectively. The maximum noise equivalent count rate (NEC) for a rat phantom was 82 kcps at 75 MBq and 88 kcps at 75 MBq for energy window of 250-750 and 400-620 keV, respectively. For the monkey phantom, the maximum NEC was 18 kcps at 126 MBq and 19 kcps at 126 MBq for energy window of 250-750 and 400-620 keV, respectively. The IRIS XL provided an excellent quality of images in non-human primates and rats using ¹⁸F-FDG. The images acquired using (-)-[¹⁸F]FEOBV were consistent with those previously reported in non-human primates.

CONCLUSIONS

Taken together, these results showed that the IRIS XL-220 is a high-resolution system well suited for PET/CT imaging in non-human primates.

Monte Carlo Characterization of the Trimage Brain PET System

The TRIMAGE project aims to develop a brain-dedicated PET/MR/EEG (Positron Emission Tomography/Magnetic Resonance/Electroencephalogram) system that is able to perform simultaneous PET, MR and EEG acquisitions. The PET component consists of a full ring with 18 sectors. Each sector includes three square detector modules based on dual sstaggered LYSO:Ce matrices read out by SiPMs. Using Monte Carlo simulations and following NEMA (National Electrical Manufacturers Association) guidelines, image quality procedures have been applied to evaluate the performance of the PET component of the system. The performance are reported in terms of spatial resolution, uniformity, recovery coefficient, spill over ratio, noise equivalent count rate (NECR) and scatter fraction. The results show that the TRIMAGE system is at the top of the current brain PET technologies.

Localization of anatomical changes in patients during proton therapy with in-beam PET monitoring: A voxel-based morphometry approach exploiting Monte Carlo simulations

Purpose

In‐beam positron emission tomography (PET) is one of the modalities that can be used for in vivo noninvasive treatment monitoring in proton therapy. Although PET monitoring has been frequently applied for this purpose, there is still no straightforward method to translate the information obtained from the PET images into easy‐to‐interpret information for clinical personnel. The purpose of this work is to propose a statistical method for analyzing in‐beam PET monitoring images that can be used to locate, quantify, and visualize regions with possible morphological changes occurring over the course of treatment.

Methods

We selected a patient treated for squamous cell carcinoma (SCC) with proton therapy, to perform multiple Monte Carlo (MC) simulations of the expected PET signal at the start of treatment, and to study how the PET signal may change along the treatment course due to morphological changes. We performed voxel‐wise two‐tailed statistical tests of the simulated PET images, resembling the voxel‐based morphometry (VBM) method commonly used in neuroimaging data analysis, to locate regions with significant morphological changes and to quantify the change.

Results

The VBM resembling method has been successfully applied to the simulated in‐beam PET images, despite the fact that such images suffer from image artifacts and limited statistics. Three dimensional probability maps were obtained, that allowed to identify interfractional morphological changes and to visualize them superimposed on the computed tomography (CT) scan. In particular, the characteristic color patterns resulting from the two‐tailed statistical tests lend themselves to trigger alarms in case of morphological changes along the course of treatment.

Conclusions

The statistical method presented in this work is a promising method to apply to PET monitoring data to reveal interfractional morphological changes in patients, occurring over the course of treatment. Based on simulated in‐beam PET treatment monitoring images, we showed that with our method it was possible to correctly identify the regions that changed. Moreover we could quantify the changes, and visualize them superimposed on the CT scan. The proposed method can possibly help clinical personnel in the replanning procedure in adaptive proton therapy treatments.

Monitoring Carbon Ion Beams Transverse Position Detecting Charged Secondary Fragments: Results From Patient Treatment Performed at CNAO

Particle therapy in which deep seated tumours are treated using ¹²C ions (Carbon Ions RadioTherapy or CIRT) exploits the high conformity in the dose release, the high relative biological effectiveness and low oxygen enhancement ratio of such projectiles. The advantages of CIRT are driving a rapid increase in the number of centres that are trying to implement such technique. To fully profit from the ballistic precision achievable in delivering the dose to the target volume an online range verification system would be needed, but currently missing. The ¹²C ions beams range could only be monitored by looking at the secondary radiation emitted by the primary beam interaction with the patient tissues and no technical solution capable of the needed precision has been adopted in the clinical centres yet. The detection of charged secondary fragments, mainly protons, emitted by the patient is a promising approach, and is currently being explored in clinical trials at CNAO. Charged particles are easy to detect and can be back-tracked to the emission point with high efficiency in an almost background-free environment. These fragments are the product of projectiles fragmentation, and are hence mainly produced along the beam path inside the patient. This experimental signature can be used to monitor the beam position in the plane orthogonal to its flight direction, providing an online feedback to the beam transverse position monitor chambers used in the clinical centres. This information could be used to cross-check, validate and calibrate, whenever needed, the information provided by the ion chambers already implemented in most clinical centres as beam control detectors. In this paper we study the feasibility of such strategy in the clinical routine, analysing the data collected during the clinical trial performed at the CNAO facility on patients treated using ¹²C ions and monitored using the Dose Profiler (DP) detector developed within the INSIDE project. On the basis of the data collected monitoring three patients, the technique potential and limitations will be discussed.

Inter-fractional monitoring of [Formula: see text]C ions treatments: results from a clinical trial at the CNAO facility

The high dose conformity and healthy tissue sparing achievable in Particle Therapy when using C ions calls for safety factors in treatment planning, to prevent the tumor under-dosage related to the possible occurrence of inter-fractional morphological changes during a treatment. This limitation could be overcome by a range monitor, still missing in clinical routine, capable of providing on-line feedback. The Dose Profiler (DP) is a detector developed within the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) collaboration for the monitoring of carbon ion treatments at the CNAO facility (Centro Nazionale di Adroterapia Oncologica) exploiting the detection of charged secondary fragments that escape from the patient. The DP capability to detect inter-fractional changes is demonstrated by comparing the obtained fragment emission maps in different fractions of the treatments enrolled in the first ever clinical trial of such a monitoring system, performed at CNAO. The case of a CNAO patient that underwent a significant morphological change is presented in detail, focusing on the implications that can be drawn for the achievable inter-fractional monitoring DP sensitivity in real clinical conditions. The results have been cross-checked against a simulation study.

Particle beam microstructure reconstruction and coincidence discrimination in PET monitoring for hadron therapy

Positron emission tomography is one of the most mature techniques for monitoring the particles range in hadron therapy, aiming to reduce treatment uncertainties and therefore the extent of safety margins in the treatment plan. In-beam PET monitoring has been already performed using inter-spill and post-irradiation data, i.e. while the particle beam is off or paused. The full beam acquisition procedure is commonly discarded because the particle spills abruptly increase the random coincidence rates and therefore the image noise. This is because random coincidences cannot be separated by annihilation photons originating from radioactive decays and cannot be corrected with standard random coincidence techniques due to the time correlation of the beam-induced background with the ion beam microstructure. The aim of this paper is to provide a new method to recover in-spill data to improve the images obtained with full-beam PET acquisitions. This is done by estimating the temporal microstructure of the beam and thus selecting input PET events that are less likely to be random ones. The PET detector we used was the one developed within the INSIDE project and tested at the CNAO synchrotron-based facility. The data were taken on a PMMA phantom irradiated with 72 MeV proton pencil beams. The obtained results confirm the possibility of improving the acquired PET data without any external signal coming from the synchrotron or ad hoc detectors.

A Monte Carlo detector response model for the IRIS PET preclinical scanner

PET preclinical studies require high spatial resolution due to the limited size of the animal under investigation. To achieve this target, iterative image reconstruction algorithms are commonly preferred over the analytical methods because they offer the possibility of accurately modeling the whole imaging process. In this work, we propose an accurate factorized system matrix for the INVISCAN IRIS preclinical PET scanner to be used with an iterative algorithm. The model includes two components: the geometric component and the detector response of the system. The main innovative aspect of the work is the creation of the detector matrix using a Monte Carlo simulation, with a particular focus on the optimization of the simulation process to reduce the calculation time. The new system model is compared with the current IRIS model to evaluate the image quality, following the NEMA Standards NU 4-2008. The comparison showed an enhancement of the image quality, in terms of uniformity and recovery coefficients. This work confirms that the inclusion of the detector response into the system model leads to improved reconstruction results.

An automatic algorithm to exploit the symmetries of the system response matrix in positron emission tomography iterative reconstruction

Positron emission tomography (PET) iterative 3D reconstruction is a very computational demanding task. One of the main issues of the iterative reconstruction concerns the management of the system response matrix (SRM). The SRM models the relationship between the projection and the voxel space and its memory footprint can easily exceed hundreds of GB. Moreover, in order to make the reconstruction fast enough not to hinder its practical application, the SRM must be stored in the random access memory of the workstation used for the reconstruction. This issue is normally solved by implementing efficient storage schemes and by reducing the number of redundant patterns in the SRM through symmetries. However, finding a sufficient number of symmetries is often non-trivial and is typically performed using dedicated solutions that cannot be exported to different detectors and geometries. In this paper, an automatic approach to reduce the memory footprint of a pre-computed SRM is described. The proposed approach was named symmetry search algorithm (SSA) and consists in an algorithm that searches for some of the redundant patterns present in the SRM, leading to its lossy compression. This approach was built to detect translations, reflections and coordinates swap in voxel space. Therefore, it is particularly well suited for those scanners where some of the rotational symmetries are broken, e.g. small animal scanner where the modules are arranged in a polygonal ring made of few elements, and dual head planar PET systems. In order to validate this approach, the SSA is applied to the SRM of a preclinical scanner (the IRIS PET/CT). The data acquired by the scanner were reconstructed with a dedicated maximum likelihood estimation maximization algorithm with both the uncompressed and the compressed SRMs. The results achieved show that the information lost due to the SSA compression is negligible. Compression factors up to 52 when using the SSA together with manually inserted symmetries and up to 204 when using the SSA alone, can be obtained for the IRIS SRM. These results come without significant differences in the values and in the main quality metrics of the reconstructed images, i.e. spatial resolution and noise. Although the compression factors depend on the system considered, the SSA is applicable to any SRM and therefore it can be considered a general tool to reduce the footprint of a pre-computed SRM.

Carbon ions beam therapy monitoring with the INSIDE in-beam PET

In vivo range monitoring techniques are necessary in order to fully take advantage of the high dose gradients deliverable in hadrontherapy treatments. Positron emission tomography (PET) scanners can be used to monitor beam-induced activation in tissues and hence measure the range. The INSIDE (Innovative Solutions for In-beam DosimEtry in Hadrontherapy) in-beam PET scanner, installed at the Italian National Center of Oncological Hadrontherapy (CNAO, Pavia, Italy) synchrotron facility, has already been successfully tested in vivo during a proton therapy treatment. We discuss here the system performance evaluation with carbon ion beams, in view of future in vivo tests. The work is focused on the analysis of activity images obtained with therapeutic treatments delivered to polymethyl methacrylate (PMMA) phantoms, as well as on the test of an innovative and robust Monte Carlo simulation technique for the production of reliable prior activity maps. Images are reconstructed using different integration intervals, so as to monitor the activity evolution during and after the treatment. Three procedures to compare activity images are presented, namely Pearson correlation coefficient, Beam's eye view and overall view. Images of repeated irradiations of the same treatments are compared to assess the integration time necessary to provide reproducible images. The range agreement between simulated and experimental images is also evaluated, so as to validate the simulation capability to provide sound prior information. The results indicate that at treatment end, or at most 20 s afterwards, the range measurement is reliable within 1-2 mm, when comparing both different experimental sessions and data with simulations. In conclusion, this work shows that the INSIDE in-beam PET scanner performance is promising towards its in vivo test with carbon ions.

Primary Malignant Fibrous Histiocytoma of Storiform-Pleomorphic Type: A Case Report of an Ano-Rectal Localization

Among the various localizations of primary malignant histiocytoma, the ano-rectal one is exceedingly rare. In this paper we report a case characterized by a storiform-pleomorphic pattern of the tumor and a rapid fatal course of the disease with metastasis in the lungs. The prognostic value of the histologic features is briefly discussed.

Online proton therapy monitoring: clinical test of a Silicon-photodetector-based in-beam PET

Particle therapy exploits the energy deposition pattern of hadron beams. The narrow Bragg Peak at the end of range is a major advantage but range uncertainties can cause severe damage and require online verification to maximise the effectiveness in clinics. In-beam Positron Emission Tomography (PET) is a non-invasive, promising in-vivo technique, which consists in the measurement of the β+ activity induced by beam-tissue interactions during treatment, and presents the highest correlation of the measured activity distribution with the deposited dose, since it is not much influenced by biological washout. Here we report the first clinical results obtained with a state-of-the-art in-beam PET scanner, with on-the-fly reconstruction of the activity distribution during irradiation. An automated time-resolved quantitative analysis was tested on a lacrimal gland carcinoma case, monitored during two consecutive treatment sessions. The 3D activity map was reconstructed every 10 s, with an average delay between beam delivery and image availability of about 6 s. The correlation coefficient of 3D activity maps for the two sessions (above 0.9 after 120 s) and the range agreement (within 1 mm) prove the suitability of in-beam PET for online range verification during treatment, a crucial step towards adaptive strategies in particle therapy.

TRIMAGE: A dedicated trimodality (PET/MR/EEG) imaging tool for schizophrenia

Simultaneous PET/MR/EEG (Positron Emission Tomography - Magnetic Resonance - Electroencephalography), a new tool for the investigation of neuronal networks in the human brain, is presented here within the framework of the European Union Project TRIMAGE. The trimodal, cost-effective PET/MR/EEG imaging tool makes use of cutting edge technology both in PET and in MR fields. A novel type of magnet (1.5T, non-cryogenic) has been built together with a PET scanner that makes use of the most advanced photodetectors (i.e., SiPM matrices), scintillators matrices (LYSO) and digital electronics. The combined PET/MR/EEG system is dedicated to brain imaging and has an inner diameter of 260 mm and an axial Field-of-View of 160 mm. It enables the acquisition and assessment of molecular metabolic information with high spatial and temporal resolution in a given brain simultaneously. The dopaminergic system and the glutamatergic system in schizophrenic patients are investigated via PET, the same physiological/pathophysiological conditions with regard to functional connectivity, via fMRI, and its electrophysiological signature via EEG. In addition to basic neuroscience questions addressing neurovascular-metabolic coupling, this new methodology lays the foundation for individual physiological and pathological fingerprints for a wide research field addressing healthy aging, gender effects, plasticity and different psychiatric and neurological diseases. The preliminary performances of two components of the imaging tool (PET and MR) are discussed. Initial results of the search of possible candidates for suitable schizophrenia biomarkers are also presented as obtained with PET/MR systems available to the collaboration.

[Rubber band ligation in treatment of hemorrhoids: our experience]

OBJECTIVES

Hemorrhoids are a very common condition. The treatment depends upon persistence and severity of symptoms. For hemorrhoids of II and III grade the rubber band ligation may be therapeutic. Our aim is to report the outcomes of rubber band ligation of hemorrhoids, with a follow up of 6 months.

MATERIALS AND METHODS

A total of 50 patients underwent rubber band ligation for symptomatic hemorrhoids (grade II and III) without prolapse, between June 2012 and June 2014. All patients underwent plug test to rule out presence of rectal mucosal prolapse and were classified according to PATE classification (1). Each hemorrhoid was ligated with one rubber band through a ligator. All patients were evaluated immediately at the end of the procedure, after ten days and six months after the treatment. Patient's demographic and operative data were collected and analyzed.

RESULTS

The mean patients age was 47.6±12.3 years (range 24-72). All procedures were performed without complications. Before rubber band ligation, 42 patients had rectal bleeding, 38 had perineal discomfort and 27 had itching. Ten days after the treatment, 12 patients presented self-limited rectal bleeding, but 10 of these had more hemorrhoids and underwent a second rubber band ligation. No patients complained perineal discomfort, and 8 patients had itching; 78% and 16% of patients respectively, experienced feeling of a foreign body inside the canal anal and anal pain. After 6 months, only 13 patients were occasionally symptomatic: 4 patients had rectal bleeding, 2 had perineal discomfort and 4 had itching. Three more patients presented both perineal discomfort and hitching. None had the feeling of a foreign body in anal canal or anal pain.

CONCLUSIONS

Rubber band ligation is an efficacious, cost-effective and simple treatment for the second and third degree hemorrhoids without rectal mucosal prolapsed. In our hands, no severe complications developed and minor complications could be handled with ease.

Full-beam performances of a PET detector with synchrotron therapeutic proton beams

Treatment quality assessment is a crucial feature for both present and next-generation ion therapy facilities. Several approaches are being explored, based on prompt radiation emission or on PET signals by [Formula: see text]-decaying isotopes generated by beam interactions with the body. In-beam PET monitoring at synchrotron-based ion therapy facilities has already been performed, either based on inter-spill data only, to avoid the influence of the prompt radiation, or including both in-spill and inter-spill data. However, the PET images either suffer of poor statistics (inter-spill) or are more influenced by the background induced by prompt radiation (in-spill). Both those problems are expected to worsen for accelerators with improved duty cycle where the inter-spill interval is reduced to shorten the treatment time. With the aim of assessing the detector performance and developing techniques for background reduction, a test of an in-beam PET detector prototype was performed at the CNAO synchrotron-based ion therapy facility in full-beam acquisition modality. Data taken with proton beams impinging on PMMA phantoms showed the system acquisition capability and the resulting activity distribution, separately reconstructed for the in-spill and the inter-spill data. The coincidence time resolution for in-spill and inter-spill data shows a good agreement, with a slight deterioration during the spill. The data selection technique allows the identification and rejection of most of the background originated during the beam delivery. The activity range difference between two different proton beam energies (68 and 72 MeV) was measured and found to be in sub-millimeter agreement with the expected result. However, a slightly longer (2 mm) absolute profile length is obtained for in-spill data when compared to inter-spill data.

INSIDE in-beam positron emission tomography system for particle range monitoring in hadrontherapy

The quality assurance of particle therapy treatment is a fundamental issue that can be addressed by developing reliable monitoring techniques and indicators of the treatment plan correctness. Among the available imaging techniques, positron emission tomography (PET) has long been investigated and then clinically applied to proton and carbon beams. In 2013, the Innovative Solutions for Dosimetry in Hadrontherapy (INSIDE) collaboration proposed an innovative bimodal imaging concept that combines an in-beam PET scanner with a tracking system for charged particle imaging. This paper presents the general architecture of the INSIDE project but focuses on the in-beam PET scanner that has been designed to reconstruct the particles range with millimetric resolution within a fraction of the dose delivered in a treatment of head and neck tumors. The in-beam PET scanner has been recently installed at the Italian National Center of Oncologic Hadrontherapy (CNAO) in Pavia, Italy, and the commissioning phase has just started. The results of the first beam test with clinical proton beams on phantoms clearly show the capability of the in-beam PET to operate during the irradiation delivery and to reconstruct on-line the beam-induced activity map. The accuracy in the activity distal fall-off determination is millimetric for therapeutic doses.

[Mucoprolassectomy with circular stapler: early results with a new device]

AIMS

Stapled transanal mucosectomy is widely used by a lot of surgeon and in RCT, when compared to other haemorrhoidectomy techniques, it didn't show a real primacy. We describe results obtained with a new device, the EEA™ 33-mm Hemorrhoid and Prolapse Stapler Set con DST Series™ (Covidien™), used on 65 patients.

PATIENTS AND METHODS

Sixty-five patients underwent a stapled transanal mucosectomy for grade III (n° 20), IV (n° 15) haemorrhois and rectal prolapse (n° 30). The operation were performed by two surgeons. Results. Resected tissue had a mean width of 4.2 cm (3.3-6.1 cm) and a mean weight of 11 g (8-21 g). Surgical time were 22 min (15-35 min). Bleeding of the suture line were observed in 5 cases (7.7%) and they required a mean of 2 haemostatic stitch (1-5) in adsorbable suture 2/0. Mucoprolapsectomy was considered excellent in 55 patients (84.7%), good in 8 patients (12.3%), bad in 2 patients (3%) by surgeons. There were no early and late complications like bleeding, abscesses, anastomotic dehiscence. We report two case of perianal haematoma that don't need any treatment and one case of anal stenosis treated with dilatation therapy. Post-operative pain, estimated with VAS, emphasized an excellent response to NSAIDs in first postoperative day, in 10 cases (15.4%) we prolonged analgesic therapy for 3 days, in one case (1.5%) for one week. After 6 month all patients were revaluated with physical examination and anoscopy. Only one patient (1.5%) had an asymptomatic recurrence of rectal prolapse.

CONCLUSION

We conclude that the new device makes easy and standardized surgery. The new device reduce a lot of difficult in patients with tight pelvis and a small distance between ischiatic tubers.

Stapled hemorrhoidopexy in the treatment of hemorrhoid disease. Our eight-year experience

AIM

Stapled hemorrohoidopexy using Longo technique (PPH) is accompanied by good postoperative outcomes. The aim of this study was to report the data regarding our experience with stapled hemorrhoidopexy, the results of the operations and the complications rate in comparison with those published in the literature.

METHODS

In our Department 127 patients with symptomatic hemorrhoids have been selected between November 2000 and December 2008 for PPH. This retrospective study included patients with a rectal prolapse from second to fourth degree.

RESULTS

Two patients had an anal bleeding on the day of surgery. All of them were returned to the operating theatre. A third patient had an anal bleeding that did not require a second surgical intervention. In one case a postoperative stenosis occurred that required a reoperation three days after the dismission from hospital. In one case an urgency occurred, with transitional fecal incontinence, spontaneously regressed two weeks after the intervention. No urinary retention occurred in our caseload. Pain was referred by 37 patients and was controlled by standard analgesia in all cases. No cases of chronic pain were detected. There were no cases of anal stenosis, permanent incontinence or deaths in this series.

CONCLUSION

Among the cases examined important complications occurred in five (3.9%), but reintervention was necessary only for three patients (2.4%). This study confirms that PPH, used on patients with a rectal prolapse from second to fourth degree, is feasible and safe.

[Proctological surgery: use of a salsobromoiodic gel solution in the post-operative period]

BACKGROUND

This study was aimed to demonstrate the advantages and the efficacy of a salsobromoiodic gel solution sponge to use in coloproctology after surgery for the most frequent pathologies of anal canal and of perineal region.

MATERIALS AND METHODS

The Authors have tested the salsobromoiodic gel solution (Fertomcidina U) in a consecutive series of patients referred to 5 coloproctological centers where they have been submitted to surgery for pathologies of anal canal and of perineal region. A total of 30 patients, 15 with clinico-instrumental diagnosis of III-IV degree haemorrhoids and 15 with diagnosis of chronic anal fissure entered in a clinical follow-up after an out-patient setting or surgery for the respective pathologies. The gel formulation is realized as a salsobromoiodic solution containing salicylic acid and magnesium biphosphate making a strong bactericide and fungicide action applicable on human skin for tissues reparation and their re-epithelization. The experimental treatment was performed on the duration of at least 10 days, with two topic applications.

RESULT

In 100% of the treated patients, the used gel has determined the prevention of infective complications, favouring a normal re-epithelization of tissue submitted to surgery or affected by previous anal mucosal lesions. The use of gel has not caused irritation and skin damage. No symptom and sign of toxicity were observed.

CONCLUSIONS

The use of salsobromoiodic gel solution has been useful to prevent infections and to contribute to the cicatrisation, healing and re-epithelization of anal mucosal lesions after surgery on a normal outpatients setting. The use of gel formulation resulted easy and satisfactory for the patients affected by the most frequent proctological pathologies which require a surgical treatment.

Palliative treatment of upper gastrointestinal obstruction using self-expansible metal stents

Gastric outlet obstruction is either a late event in the natural history of bilio-pancreatic tumors or the result of recurrent gastric or pancreatic tumors. Self-expansible metal stents, inserted under endoscopic and fluoroscopic control, can be used for palliative treatment. The present study was aimed at evaluating both the feasibility and the results of stenting in patients with malignant gastric outlet obstruction; in addition, some technical suggestions are presented. A total of 33 patients, who had a metal stent positioned, were retrospectively evaluated; 20 of them were women and 13 were men, aged from 45 to 94 years, with a mean age of 75 years. Twenty-seven patients had a pancreatic adenocarcinoma, 4 had a stricture of a gastrojejunal anastomosis due to recurrent pancreatic tumor, 2 had a stricture of a gastrojejunal anastomosis secondary to gastric cancer surgery. No postoperatory complications were observed. Improvement in the quality of life was obtained in all patients. Following the stenting procedure, the median duration of hospitalization was 8 days (range: 6-20 days), and the mean survival rate was 12 weeks (range: 2-66 weeks). Endoscopic stenting for the palliation of malignant gastric outlet obstruction is feasible and is well tolerated by most patients. In some cases a period of enteral nutrition had to be necessarily carried out; nonetheless, the insertion of the stent improved the quality of life.

Giant mesenteric fibromatosis

Mesenteric fibromatosis is a proliferative fibroblastic neoplasia of the small intestine mesentery which may occur as a unique or multiple formation. Mesenteric fibromatosis represents the 8% of all desmoid neoplasm. Giant mesenteric fibromatosis is uncommon by itself (2-4 case/milion/year). Since the rarity of this tumor and the difficulties in diagnostic and therapeutic ambit, we believe it justified to describe a case of giant mesenteric fibromatosis which came to our observation.

Palliative treatment for malignant jaundice: endoscopic vs surgical approach

In this retrospective, comparative study a total of 107 patients, presenting with malignant inoperable strictures of common bile duct, due to a pancreatico-biliary malignancy, underwent palliative treatments. In a group, consisting of 82 patients (76.64%), endoscopic stenting procedures were performed; polyethylene stents or self-expanding metal stents were applied in 37 and 45 patients, respectively. The prerequisites for a successful endoscopic stenting were a) accuracy of diagnosis and b) exclusion of patients presenting with tumors potentially treatable by a curative resection. In the other group, consisting of 25 patients (23.36%), biliary-enteric bypass procedures were performed. Endoscopic treatment was successful in 97.5% of the cases (80/82); complication rate was 7.3% (6 patients on 82), and mortality rate was 3.6% (3 patients on 82). Median hospital stay was 13.4 and 7.3 days in patients treated with plastic stents and metallic stents, respectively. Bypass surgery was successful in 99% of the cases (24/25); complication rate was 24% (6 patients on 25), and mortality rate was 16% (4 patients on 25). Median hospital stay was 26 days. For the patients in whom a curative resection could not be performed, both the above mentioned methods resulted in a high rate of immediate technical and therapeutic success. However, the surgical approach showed a significantly higher rate in procedure-related mortality and morbidity; in addition, the hospital stay lasted longer in surgically treated patients. The patients who are definitely unsuitable for curative resection are better managed by positioning a stent. The use of metal stents should be preferred in those less serious patients who may supposedly survive longer.

Rapidly destructive bilateral hip disease: a case report and review of the literature

We describe the case of an elderly woman with rapid destruction of the right hip followed by the same involvement of her left hip 10 months later. The clinical history, the physical examination and radiographic images suggested the diagnosis of rapidly destructive hip disease. This disease is a distinct entity, unilateral in 80%-90% of cases, which requires extensive investigation and special efforts for its identification. Essential elements for the differential diagnosis are discussed.

ERCP and acute pancreatitis

Acute biliary pancreatitis (ABP) is a serious complication of biliary stones disease and is associated with significant morbidity and mortality. The role of ERCP in the management of ABP has been the focus of discussion in recent years. In this report, we evaluated a protocol of emergency Endoscopic retrograde Cholangiopancreatography (ERCP) (within 24 hours) and early ERCP (within 72 hours). From July 1997 to July 2000, were observed 45 patients (19 man and 26 women) with acute biliary pancreatitis. Mean age of patients was 63.4 years (range 21-87 years). Diagnosis of ABP was based on anamnesis and clinical assessment and was confirmed by specific laboratory data (hyperamylasemia, hyperlipasemia, total and fractionated bilirubinemia, gamma-GT, transaminase, alkaline phosphatase, hypocalcemia, hyperglycemia, leukocytosis). Ultrasound scanning within 24 h of admission was performed in 45 patients (100%) and it revealed gallbladder stones and muddy bile in 39 patients (87%). Computed tomography (CT) performed in all patients, showed a severe acute pancreatitis in the second or subsequent week following admission. The severity of acute pancreatitis was established by Glasgow's criteria and by clinical details of patients. ERCP and Endoscopic Sphinterotomy (ES) was performed in all 45 patients with acute biliary pancreatitis. Twenty-six patients (57%) were classified as having a severe attack (> 4) 19 as having a mild attack by Glasgow's criteria. ERCP associated with ES was performed within 24 hours in 22 patients (49%), 11 (50%) showed a severe attack and 11 (50%) showed a mild attack. A total of 2 complications (4%) occurred and the mortality was of 2 patients (4%). In 23 patients (51%) ERCP and ES was performed within 72 hours after conservative therapy, 8 (35%) showed a mild attack and 15 (65%) showed a severe attack. A total of 5 complications (9%) occurred and the mortality was of 3 patients (6%). Our study showed that ERCP with endoscopic sphincterotomy can be performed safely by skilled endoscopist, without adverse consequences soon after the onset of acute biliary pancreatitis even within the first 24 hours and it showed that is better than ERCP within 72 hours after conservative therapy.

Sentinel node role in breast cancer surgery

Radical surgery of breast cancer includes lymphadenectomy of axilla as well as the dissection of the neoplastic tissue. However recently many works have raised doubts on the opportunity of performing routinary axillary dissection, which elevates morbidity risk, in absence of axillary metastases. However, unfortunately, information on axillary lymph node pathology, is not available with any other technique excluding complete dissection and istopathological examination. Sentinel node technique is a new methodology that consents evaluation of lymph node status in the operating theatre. It allows the surgeon to judge on the opportunity of carrying out the lymphadenectomy or not.

Conservative approach in the treatment of the biliary tract's iatrogenic lesions

Iatrogenic lesions of the biliary tract have always represented a problem of real actuality in the abdominal surgery. The incidence of post-cholecystectomy complications is from 0.1% to 0.25% and it's increased to 0.3-0.6% for laparoscopic surgery. Potential predisposing factors to iatrogenic biliary lesions are anatomic anomalies, acute and chronic phlogosis and technical mistakes. Anatomic anomalies are present in 6-25% of all cases according to different statistics; an incomplete knowledge of the biliary tract can predispose to a mistake legating or dissecting a wrong branch. This paper present a caseload of 27 patients admitted to our Service of Digestive Endoscopy owing to post laparoscopic cholecystectomy complications. Patients have been recruited in a period from two days to six months to the intervention. Detected complicances have been divided in "major", which comprehended biliary lesions (7 cases) and biliary stenosis (8 cases), and in "minor" which included biliary leakages (12 cases). CPRE, PTC, Ultrasound, CT and cholangio-MR were used to diagnose the biliary damage. Conservative approach has been resolutive in all patients with minor biliary lesions and in three cases of major lesions; in seven cases of biliary stenosis endoscopic-radiologic combined treatment has been successfully performed, in the other patients surgical operation was obliged choice. Comparing our results with literature we can affirm that conservative treatment represents the first choice in case of minor lesions (100% of successes), whereas in case of major biliary lesions it constitutes a valid alternative to the reparative surgery; when surgical option results impossible to defer, it can help the surgeon identifying the damage and draining the biliary tract.

Central venous catheter disruption and embolization: percutaneous retrieval. A case report

Disruption followed by intravasal embolization is a rare (0.5%) however possible complication secondary to the insertion of a central venous catheter. The carriers of these implantable systems are patients who, for their cure and at times even for their survival, require the chronic intravenous infusion of drugs and solutions. Therefore materials that can allow long-term insertion with a minimum of complications are the most suitable. There are several causes of disruption and embolization of cannulae. The most common are represented by the pinch-off syndrome and catheter disconnection from reservoir. The literature on the subject is illustrated and a personal case treated with intravascular retrieval is reported.

A multidisciplinary approach to the treatment of small-cell lung cancer: the role played by surgery

The authors report their data on 344 cases of small-cell lung cancer treated according to indications with combined chemoradiotherapy and in selected cases with surgical intervention. In patients with limited disease, the results of pharmacologic therapy significantly improve the prognosis only in association with surgery. The role of surgery has been reappraised in the treatment of small-cell lung cancer which appears, nowadays, multidisciplinary.