Three-row MRI receive array with remote circuitry to preserve radiation transparency

Objective.Up to this point, 1.5 T linac-compatible coil array layouts have been restricted to one or two rows of coils because of the desire to place radiation-opaque circuitry adjacent to the coils and outside the window through which the linac beam travels. Such layouts can limit parallel imaging performance. The purpose of this work was to design and build a three-row array in which remotely located circuits permitted a central row of coils while preserving the radiolucent window.Approach.The remote circuits consisted of a phase shifter to cancel the phase introduced by the coaxial link between the circuit and coil, followed by standard components for tuning, matching, detuning, and preamplifier decoupling. Tests were performed to compare prototype single-channel coils with remote or local circuits, which were followed by tests comparing two and three-row arrays .Main results.The single-channel coil with the remote circuit maintained 85% SNR at depths of 30 mm or more as compared to a coil with local circuit. The three-row array provided similar SNR as the two-row array, along with geometry factor advantages for parallel imaging acceleration in the head-foot direction.Significance.The remote circuit strategy could potentially support future MR-linac arrays by allowing greater flexibility in array layout compared to those confined by local circuits, which can be leveraged for parallel imaging acceleration.

Regional shear wave speeds track regional axial stress in nonuniformly loaded fibrous soft tissues

Ligaments and tendons undergo nonuniform deformation during movement. While deformations can be imaged, it remains challenging to use such information to infer regional tissue loading. Shear wave tensiometry is a promising noninvasive technique to gauge axial stress and is premised on a tensioned beam model. However, it is unknown whether tensiometry can predict regional stress in a nonuniformly loaded structure. The objectives of this study were to (1) determine whether regional shear wave speed tracks regional axial stress in nonuniformly loaded fibrous soft tissues, and (2) determine the sensitivity of regional axial stress and shear wave speed to nonuniform load distribution and fiber alignment. We created a representative set of 12,000 dynamic finite element models of a fibrous soft tissue with probabilistic variations in fiber alignment, stiffness, and aspect ratio. In each model, we applied a randomly selected nonuniform load distribution, and then excited a shear wave and tracked its regional propagation. We found that regional shear wave speed was an excellent predictor of the regional axial stress (RMSE = 0.57 MPa) and that the nature of the regional shear wave speed-stress relationship was consistent with a tensioned beam model (R2 = 0.99). Variations in nonuniform load distribution and fiber alignment did not substantially alter the wave speed-stress relationship, particularly at higher loads. Thus, these findings suggests that shear wave tensiometry could provide a quantitative estimate of regional tissue stress in ligaments and tendons.

Methodology for small animals targeted irradiations at conventional and ultra-high dose rates 65 MeV proton beam

As part of translational research projects, mice may be irradiated on radiobiology platforms such as the one at the ARRONAX cyclotron. Generally, these platforms do not feature an integrated imaging system. Moreover, in the context of ultra-high dose-rate radiotherapy (FLASH-RT), treatment planning should consider potential changes in the beam characteristics and internal movements in the animal. A patient-like set-up and methodology has been implemented to ensure target coverage during conformal irradiations of the brain, lungs and intestines. In addition, respiratory cycle amplitudes were quantified by fluoroscopic acquisitions on a mouse, to ensure organ coverage and to assess the impact of respiration during FLASH-RT using the 4D digital phantom MOBY. Furthermore, beam incidence direction was studied from mice µCBCT and Monte Carlo simulations. Finally,in vivodosimetry with dose-rate independent radiochromic films (OC-1) and their LET dependency were investigated. The immobilization system ensures that the animal is held in a safe and suitable position. The geometrical evaluation of organ coverage, after the addition of the margins around the organs, was satisfactory. Moreover, no measured differences were found between CONV and FLASH beams enabling a single model of the beamline for all planning studies. Finally, the LET-dependency of the OC-1 film was determined and experimentally verified with phantoms, as well as the feasibility of using these filmsin vivoto validate the targeting. The methodology developed ensures accurate and reproducible preclinical irradiations in CONV and FLASH-RT without in-room image guidance in terms of positioning, dose calculation andin vivodosimetry.

Mini-GRID radiotherapy on the CLEAR very-high-energy electron beamline: collimator optimization, film dosimetry, and Monte Carlo simulations

Objective.Spatially-fractionated radiotherapy (SFRT) delivered with a very-high-energy electron (VHEE) beam and a mini-GRID collimator was investigated to achieve synergistic normal tissue-sparing through spatial fractionation and the FLASH effect.Approach.A tungsten mini-GRID collimator for delivering VHEE SFRT was optimized using Monte Carlo (MC) simulations. Peak-to-valley dose ratios (PVDRs), depths of convergence (DoCs, PVDR ≤ 1.1), and peak and valley doses in a water phantom from a simulated 150 MeV VHEE source were evaluated. Collimator thickness, hole width, and septal width were varied to determine an optimal value for each parameter that maximized PVDR and DoC. The optimized collimator (20 mm thick rectangular prism with a 15 mm × 15 mm face with a 7 × 7 array of 0.5 mm holes separated by 1.1 mm septa) was 3D-printed and used for VHEE irradiations with the CERN linear electron accelerator for research beam. Open beam and mini-GRID irradiations were performed at 140, 175, and 200 MeV and dose was recorded with radiochromic films in a water tank. PVDR, central-axis (CAX) and valley dose rates and DoCs were evaluated.Main results.Films demonstrated peak and valley dose rates on the order of 100 s of MGy/s, which could promote FLASH-sparing effects. Across the three energies, PVDRs of 2-4 at 13 mm depth and DoCs between 39 and 47 mm were achieved. Open beam and mini-GRID MC simulations were run to replicate the film results at 200 MeV. For the mini-GRID irradiations, the film CAX dose was on average 15% higher, the film valley dose was 28% higher, and the film PVDR was 15% lower than calculated by MC.Significance.Ultimately, the PVDRs and DoCs were determined to be too low for a significant potential for SFRT tissue-sparing effects to be present, particularly at depth. Further beam delivery optimization and investigations of new means of spatial fractionation are warranted.

Determination of thePrpand radial dose correction factor in reference dosimetry

Objectives.In an addendum to AAPM TG-51 protocol, McEwenet al, (DOI:10.1118/1.4866223) introduced a new factorPrpto account for the radial dose distribution of the photon beam over the detector volume mainly in flattening filter free (FFF) beams.Prpand its extension to non-FFF beam reference dosimetry is investigated to see its impact in a clinical situation.Approches.ThePrpwas measured using simplified version of Sudhyadhomet al(DOI:10.1118/1.4941691) for Elekta and Varian FFF beams with two commonly used calibration detectors; PTW-30013 and Exradin-A12 ion chambers after acquiring high resolution profiles in detectors cardinal coordinates. For radial dose correction factor, the ion chambers were placed in a small water phantom and the central axis position was set to center of the sensitive volume on the treatment table and was studied by rotating the table by 15-degree interval from -90 to +90 degrees with respect to the initial (zero) position.Main results.The magnitude ofPrpvaries very little with machine, detector and beam energies to a value of 1.003 ± 0.0005 and 1.005 ± 0.0005 for 6FFF and 10FFF, respectively. The radial anisotropy for the Elekta machine with Exradin-A12 and PTW-30013 detector the magnitudes are in the range of (0.9995±0.0011 to 1.0015±0.0010) and (0.9998±0.0007 to 1.0015±0.0010), respectively. Similarly, for the Varian machine with Exradin-A12 and PTW-30013 ion chambers, the magnitudes are in the range of (1.0004±0.0010 to 1.0018±0.0018) and (1.0006±0.0009 to 1.0027±0.0007), respectively.Significance.ThePrpis ≤ 0.3% and 0.5% for 6FFF and 10FFF, respectively. The radial dose correction factor in regular beams also does not impact the dosimetry where the maximum magnitude is ±0.2% which is within experimental uncertainty.

Comparison of fludarabine/melphalan (FluMel) with fludarabine/melphalan/BCNU or thiotepa (FBM/FTM) in patients with AML in first complete remission undergoing allogeneic hematopoietic stem cell transplantation - a registry study on behalf of the EBMT Acute Leukemia Working Party

Conditioning protocols for patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) are being developed continuously to improve their anti-leukemic efficacy and reduce their toxicity. In this study, we compared the conditioning protocol of fludarabine with melphalan 140 mg/m2 (FluMel) with conditioning protocols based on this same backbone but with an additional alkylating agent i.e., either fludarabine/BCNU (also known as carmustine)/melphalan (FBM), or fludarabine/thiotepa/melphalan (FTM) 110 mg/m2. We included 1272 adult patients (FluMel, n = 1002; FBM/FTM, n = 270) with acute myeloid leukemia (AML) with intermediate/poor cytogenetic risk in first complete remission (CR) from the registry of the EBMT Acute Leukemia Working Party. Despite patients in the FBM/FTM group were older (64.1 years vs. 59.8 years, p < 0.001) and had a worse Karnofsky performance score (KPS < 90, 33% vs. 24%, p = 0.003), they showed a better overall survival (OS) (2 y OS: 68.3% vs. 58.1%, p = 0.02) and less non-relapse mortality (NRM) (2 y NRM: 15.8% vs. 22.2%, p = 0.009) compared to patients treated with FluMel. No significant differences were observed in relapse incidence (RI) (2 y RI: 24.9% vs. 23.7%, p = 0.62). In conclusion, the addition of a second alkylating agent (BCNU/carmustine or thiotepa) to FluMel as FBM/FTM conditioning, improves OS in AML patients in first CR with intermediate/poor risk cytogenetics after allo-HCT.

Association Between Diverse Cell Death Patterns Related Gene Signature and Prognosis, Drug Sensitivity, and Immune Microenvironment in Glioblastoma

Glioblastoma (GBM) is the most invasive type of glioma and is difficult to treat. Diverse programmed cell death (PCD) patterns have a significant association with tumor initiation and progression. A novel prognostic model based on PCD genes may serve as an effective tool to predict the prognosis of GBM. The study incorporated 11 PCD patterns, namely apoptosis, necroptosis, pyroptosis, ferroptosis, cuproptosis, entotic cell death, netotic cell death, parthanatos, lysosome-dependent cell death, autophagy-dependent cell death, alkaliptosis, and oxeiptosis, to develop the model. To construct and validate the model, both bulk and single-cell transcriptome data, along with corresponding clinical data from GBM cases, were obtained from the TCGA-GBM, REMBRANDT, CGGA, and GSE162631 datasets. A cell death-related signature containing 14 genes was constructed with the TCGA-GBM cohort and validated in the REMBRANDT and CGGA datasets. GBM patients with a higher cell death index (CDI) were significantly associated with poorer survival outcomes. Two separate clusters associated with clinical outcomes emerged from unsupervised analysis. A multivariate Cox regression analysis was conducted to examine the association of CDI with clinical characteristics, and a prognostic nomogram was developed. Drug sensitivity analysis revealed high-CDI GBM patients might be resistant to carmustine while sensitive to 5-fluorouracil. Less abundance of natural killer cells was found in GBM cases with high CDI and bulk transcriptome data. A cell death-related prognostic model that could predict the prognosis of GBM patients with good performance was established, which could discriminate between the prognosis and drug sensitivity of GBM.

Development of a prognostic model for glioblastoma multiforme based on the expression levels of efferocytosis-related genes

Glioblastoma multiforme (GBM) is one of the most common and aggressive brain tumors. The microenvironment of GBM is characterized by its highly immunosuppressive nature with infiltration of immunosuppressive cells and the expression levels of cytokines. Efferocytosis is a biological process in which phagocytes remove apoptotic cells and vesicles from tissues. Efferocytosis plays a noticeable function in the formation of immunosuppressive environment. This study aimed to develop an efferocytosis-related prognostic model for GBM. The bioinformatic methods were utilized to analyze the transcriptomic data of GBM and normal samples. Clinical and RNA-seq data were sourced from TCGA database comprising 167 tumor samples and 5 normal samples, and 167 tumor samples for which survival information was available. Transcriptomic data of 1034 normal samples were collected from the Genotype-Tissue Expression (GTEx) database as a control sample supplement to the TCGA database. In the end, 167 tumor samples and 1039 normal samples were obtained for transcriptome analysis. Efferocytosis-related differentially expressed genes (ERDEGs) were obtained by intersecting 7487 differentially expressed genes (DEGs) between GBM and normal samples along with 1189 hub genes. Functional enrichment analyses revealed that ERDEGs were mainly involved in cytokine-mediated immune responses. Moreover, 9 prognosis-related genes (PRGs) were identified by the least absolute shrinkage and selection operator (LASSO) regression analysis, and a prognostic model was therefore developed. The nomogram combining age and risk score could effectively predict GBM patients' prognosis. GBM patients in the high-risk group had higher immune infiltration, invasion, epithelial-mesenchymal transition, angiogenesis scores and poorer tumor purity. In addition, the high-risk group exhibited higher half maximal inhibitory concentration (IC50) values for temozolomide, carmustine, and vincristine. Expression analysis indicated that PRGs were overexpressed in GBM cells. PDIA4 knockdown reduced efferocytosis in vitro. In summary, the proposed prognostic model for GBM based on efferocytosis-related genes exhibited a robust performance.

Depth-resolved method for attenuation coefficient calculation from optical coherence tomography data for improved biological structure visualization

Optical coherence tomography (OCT) is a promising tool for intraoperative tissue morphology determination. Several studies suggest that attenuation coefficient derived from the OCT images, can differentiate between tissues of different morphology, such as normal and pathological structures of the brain, skin, and other tissues. In the present study, the depth-resolved method for attenuation coefficient calculation was adopted for the real-world situation of the depth-dependent OCT sensitivity and additive imaging noise with nonzero mean. It was shown that in the case of sharp focusing (~10 μm spot full width at half maximum [FWHM] or smaller at 1.3 μm central wavelength) only the proposed method for depth-dependent sensitivity compensation does not introduce misleading artifacts into the calculated attenuation coefficient distribution. At the same time, the scanning beam focus spot with FWHM greater than 10 μm at 1.3 μm central wavelength allows one to use multiple approaches to the attenuation coefficient calculation without introducing noticeable bias. This feature may hinder the need for robust corrections for the depth-resolved attenuation coefficient estimations from the community.

Particular issues to be considered in small field dosimetry for TrueBeam STx commissioning

This study aims to report the relevant issues concerning small fields in the commissioning of a TrueBeam STx for photon energies of 6MV, 10MV, 6FFF, and 10FFF. Percent depth doses, profiles, and field output factors were measured according to the beam model configuration of the treatment planning system. Multiple detectors were used based on the IAEA TRS-483 protocol as well as EBT3 radiochromic film. Analytical Anisotropic and Acuros XB algorithms, were configured and validated through basic dosimetry comparisons and end-to-end clinical tests.

Can Optical Surface Imaging Replace Non-coplanar Cone-beam Computed Tomography for Non-coplanar Set-up Verification in Single-isocentre Non-coplanar Stereotactic Radiosurgery and Hypofractionated Stereotactic Radiotherapy for Single and Multiple Brain Metastases?

AIMS

To conduct a direct comparison regarding the non-coplanar positioning accuracy between the optical surface imaging system Catalyst HDTM and non-coplanar cone-beam computed tomography (NC-CBCT) in intracranial single-isocentre non-coplanar stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (HSRT).

MATERIALS AND METHODS

Twenty patients with between one and five brain metastases who underwent single-isocentre non-coplanar volumetric modulated arc therapy (NC-VMAT) SRS or HSRT were enrolled in this study. For each non-zero couch angle, both Catalyst HDTM and NC-CBCT were used for set-up verification prior to beam delivery. The set-up error reported by Catalyst HDTM was compared with the set-up error derived from NC-CBCT, which was defined as the gold standard. Additionally, the dose delivery accuracy of each non-coplanar field after using Catalyst HDTM and NC-CBCT for set-up correction was measured with SRS MapCHECKTM.

RESULTS

The median set-up error differences (absolute values) between the two positioning methods were 0.30 mm, 0.40 mm, 0.50 mm, 0.15°, 0.10° and 0.10° in the vertical, longitudinal, lateral, yaw, pitch and roll directions, respectively. The largest absolute set-up error differences regarding translation and rotation were 1.5 mm and 1.1°, which occurred in the longitudinal and yaw directions, respectively. Only 35.71% of the pairs of measurements were within the tolerance of 0.5 mm and 0.5° simultaneously. In addition, the non-coplanar field with NC-CBCT correction yielded a higher gamma passing rate than that with Catalyst HDTM correction (P < 0.05), especially for evaluation criteria of 1%/1 mm with a median increase of 12.8%.

CONCLUSIONS

Catalyst HDTM may not replace NC-CBCT for non-coplanar set-up corrections in single-isocentre NC-VMAT SRS and HSRT for single and multiple brain metastases. The potential role of Catalyst HDTM in intracranial SRS/HSRT needs to be further studied in the future.

Environmental force sensing helps robots traverse cluttered large obstacles

Robots can traverse sparse obstacles by sensing environmental geometry and avoiding contact with obstacles. However, for search and rescue in rubble, environmental monitoring through dense vegetation, and planetary exploration over Martian and lunar rocks, robots must traverse cluttered obstacles as large as themselves by physically interacting with them. Previous work discovered that the forest floor-dwelling discoid cockroach and a sensor-less minimalistic robot can traverse cluttered grass-like beam obstacles of various stiffness by transitioning across different locomotor modes. Yet the animal was better at traversal than the sensor-less robot, likely by sensing forces during obstacle interaction to control its locomotor transitions. Inspired by this, here we demonstrated in simulation that environmental force sensing helps robots traverse cluttered large obstacles. First, we developed a multi-body dynamics simulation and a physics model of the minimalistic robot interacting with beams to estimate beam stiffness from the sensed contact forces. Then, we developed a force feedback strategy for the robot to use the sensed beam stiffness to choose the locomotor mode with a lower mechanical energy cost. With feedforward pushing, the robot was stuck in front of stiff beams if it has a limited force capacity; without force limit, it traversed but suffered a high energy cost. Using obstacle avoidance, the robot traversed beams by avoiding beam contact regardless of beam stiffness, resulting in a high energy cost for flimsy beams. With force feedback, the robot determined beam stiffness, then traversed flimsy beams by pushing them over and stiff beams by rolling through the gap between them with a low energy cost. Stiffness estimation based on force sensing was accurate across varied body oscillation amplitude and frequency and position sensing uncertainty. Mechanical energy cost of traversal increased with sensorimotor delay. Future work should demonstrate cluttered large obstacle traversal using force feedback in a physical robot.

Small field output correction factors at 18 MV

BACKGROUND

The response of various detectors in the radiotherapy energy range has been investigated, especially for 6 and 10 MV energies for small fields, and is summarized in TRS-483. However, data for accelerator energies above 10 MV are sparse or unavailable for many detectors, especially for the energy of 18 MV. Small variations in field output factors for the commissioning of a treatment planning system can have a high impact on calculation of dose distributions.

PURPOSE

Many studies describe an energy dependence of the response for a large number of detectors. We wanted to close the gap for the 18 MV energy regime and determined field output correction factors for different detectors at 18 MV.

METHODS

An ELEKTA Versa HD accelerator at 18 MV was used together with a PTW MP3 water phantom at an SSD of 90 cm. The following detectors were examined: PTW Semiflex 31021, PinPoint 3D 31022, diode 60012, diode 60008 and microDiamond 60019, Sun Nuclear EDGE detector, IBA PFD, SFD, Razor Chamber, Razor Nano Chamber and Razor Diode, Standard Imaging Scintillator Exradin W2 1x3, W2 1x1 and Gafchromic EBT3 film. The dose response was determined at a depth of 10 cm for square fields between 0.5 and 10 cm side length. As reference data a composure of radiochromic film data for small fields (s ≤ 3 $s\le 3$  cm) and data of all compatible chambers for larger fields (s ≥ 3 $s\ge 3$  cm) was used. The effective field sizes of small fields were determined from profiles obtained on radiochromic film. The obtained field output correction factors obey the rules of the TRS-483 protocol.

RESULTS

The W2 1x1 scintillator and the Razor Chamber showed the smallest deviations from the reference curve. The shielded diodes (diode 60008, EDGE detector) showed the highest over-response at small fields, followed by PFD, microDiamond and the unshielded diodes (diode 60012, SFD). The ionization chambers exhibited the well-known volume effect, that is, strong under-response at small fields of up to 9% for the PinPoint 3D, 7% for the Razor Chamber and up to 30% for the Semiflex detector for the smallest studied field size. The small chambers showed a polarity effect in axial orientation, especially the Razor Nano Chamber. Corrections at 18 MV are generally larger than those provided by TRS-483, continuing the trend of increasing corrections between 6 and 10 MV also at a higher accelerator energy. Only the PinPoint 3D Chamber showed a slightly smaller correction.

CONCLUSIONS

Field output correction factors were determined for square field sizes between 0.5 and 10 cm at 18 MV. Most detectors needed a larger correction than at 6 and 10 MV. Thus, the use of correction factors will improve beam data for 18 MV.

Adjacent tissues modulate shear wave propagation in axially loaded tendons

Shear wave tensiometry is a noninvasive approach for gauging tendon loads based on shear wave speed. Transient shear waves are induced and tracked via sensors secured to the skin overlying a superficial tendon. Wave speeds measured in vivo via tensiometry modulate with tendon load but are lower than that predicted by a tensioned beam model of an isolated tendon, which may be due to the added inertia of adjacent tissues. The objective of this study was to investigate the effects of adjacent fat tissue on shear wave propagation measurements in axially loaded tendons. We created a layered, dynamic finite element model of an elliptical tendon surrounded by subcutaneous fat. Transient shear waves were generated via an impulsive excitation delivered across the tendon or through the subcutaneous fat. The layered models demonstrated dispersive behavior with phase velocity increasing with frequency. Group shear wave speed could be ascertained via dispersion analysis or time-to-peak measures at sequential spatial locations. Simulated wave speeds in the tendon and adjacent fat were similar and modulated with tendon loading. However, wave speed magnitudes were consistently lower in the layered models than in an isolated tendon. For all models, the wave speed-stress relationship was well described by a tensioned beam model after accounting for the added inertia of the adjacent tissues. These results support the premise that externally excited shear waves are measurable in subcutaneous fat and modulate with axial loading in the underlying tendon. The model suggests that adjacent tissues add inertia to the system, which in turn lowers shear wave speeds. This information must be considered when using tensiometry as a clinical or research tool to infer absolute tendon loading.

3D-conformal very-high energy electron therapy as candidate modality for FLASH-RT: A treatment planning study for glioblastoma and lung cancer

BACKGROUND

Pre-clinical ultra-high dose rate (UHDR) electron irradiations on time scales of 100 ms have demonstrated a remarkable sparing of brain and lung tissues while retaining tumor efficacy when compared to conventional dose rate irradiations. While clinically-used gantries and intensity modulation techniques are too slow to match such time scales, novel very-high energy electron (VHEE, 50-250 MeV) radiotherapy (RT) devices using 3D-conformed broad VHEE beams are designed to deliver UHDR treatments that fulfill these timing requirements.

PURPOSE

To assess the dosimetric plan quality obtained using VHEE-based 3D-conformal RT (3D-CRT) for treatments of glioblastoma and lung cancer patients and compare the resulting treatment plans to those delivered by standard-of-care intensity modulated photon RT (IMRT) techniques.

METHODS

Seven glioblastoma patients and seven lung cancer patients were planned with VHEE-based 3D-CRT using 3 to 16 coplanar beams with equidistant angular spacing and energies of 100 and 200 MeV using a forward planning approach. Dose distributions, dose-volume histograms, coverage (V95% ) and homogeneity (HI98% ) for the planning target volume (PTV), as well as near-maximum doses (D2% ) and mean doses (Dmean ) for organs-at-risk (OAR) were evaluated and compared to clinical IMRT plans.

RESULTS

Mean differences of V95% and HI98% of all VHEE plans were within 2% or better of the IMRT reference plans. Glioblastoma plan dose metrics obtained with VHEE configurations of 200 MeV and 3-16 beams were either not significantly different or were significantly improved compared to the clinical IMRT reference plans. All OAR plan dose metrics evaluated for VHEE plans created using 5 beams of 100 MeV were either not significantly different or within 3% on average, except for Dmean for the body, Dmean for the brain, D2% for the brain stem, and D2% for the chiasm, which were significantly increased by 1, 2, 6, and 8 Gy, respectively (however below clinical constraints). Similarly, the dose metrics for lung cancer patients were also either not significantly different or were significantly improved compared to the reference plans for VHEE configurations with 200 MeV and 5 to 16 beams with the exception of D2% and Dmean to the spinal canal (however below clinical constraints). For the lung cancer cases, the VHEE configurations using 100 MeV or only 3 beams resulted in significantly worse dose metrics for some OAR. Differences in dose metrics were, however, strongly patient-specific and similar for some patient cases.

CONCLUSIONS

VHEE-based 3D-CRT may deliver conformal treatments to simple, mostly convex target shapes in the brain and the thorax with a limited number of critical adjacent OAR using a limited number of beams (as low as 3 to 7). Using such treatment techniques, a dosimetric plan quality comparable to that of standard-of-care IMRT can be achieved. Hence, from a treatment planning perspective, 3D-conformal UHDR VHEE treatments delivered on time scales of 100 ms represent a promising candidate technique for the clinical transfer of the FLASH effect.

Optimisation of exposure parameters using a phantom for thoracic spine radiographs in antero-posterior and lateral views

INTRODUCTION

To investigate the exposure parameters for thoracic spine/(TS) radiography that allows the image acquisition at the lowest dose possible, while maintaining an adequate image quality/(IQ) to identify all relevant anatomical criteria.

METHODS

An experimental phantom study was conducted, and 48 different radiographs of TS (24 AP/24 lateral) were acquired. The Automatic Exposure Control/(AEC) with the central sensor was used to select the beam intensity, while Source-to-Detector-Distance/(SDD) (AP:115/125 cm; Lateral:115/150 cm), tube potential (AP:70/81/90 kVp; Lateral: 81/90/102 kVp), use of grid/no grid and focal spot (fine/broad) were manipulated. IQ was assessed by observers with ViewDEX. Effective Dose (ED) was estimated using PCXMC2.0 software. Descriptive statistics paired with intraclass correlation coefficient (ICC) were applied to analyse data.

RESULTS

The ED increased with a greater SDD for lateral-view, presenting a significant difference (p = 0.038), however IQ was not affected. For both AP and lateral, the use of grid had a significant effect on ED (p < 0.001). Despite the images acquired without grid had lower IQ scores, the observers considered the IQ adequate for clinical use. A 20% reduction in ED (0.042mSv-0.033 mSv) was observed when increasing the beam energy from 70 to 90 kVp for AP grid in. The observers ICC ranged from moderate to good (0.5-0.75) in lateral and good to excellent (0.75-0.9) for AP views.

CONCLUSIONS

The optimised parameters in this context were 115 cm SDD, 90 kVp with grid for the best IQ and lowest ED. Further studies in clinical setting are necessary to enlarge the context and cover different body habitus and equipment.

IMPLICATIONS FOR PRACTICE

The SDD impacts on dose for TS; Higher kVp and grid are necessary to better image quality.

A hybrid method of correcting CBCT for proton range estimation with deep learning and deformable image registration

Objective. This study aimed to develop a novel method for generating synthetic CT (sCT) from cone-beam CT (CBCT) of the abdomen/pelvis with bowel gas pockets to facilitate estimation of proton ranges.Approach. CBCT, the same-day repeat CT, and the planning CT (pCT) of 81 pediatric patients were used for training (n= 60), validation (n= 6), and testing (n= 15) of the method. The proposed method hybridizes unsupervised deep learning (CycleGAN) and deformable image registration (DIR) of the pCT to CBCT. The CycleGAN and DIR are respectively applied to generate the geometry-weighted (high spatial-frequency) and intensity-weighted (low spatial-frequency) components of the sCT, thereby each process deals with only the component weighted toward its strength. The resultant sCT is further improved in bowel gas regions and other tissues by iteratively feeding back the sCT to adjust incorrect DIR and by increasing the contribution of the deformed pCT in regions of accurate DIR.Main results. The hybrid sCT was more accurate than deformed pCT and CycleGAN-only sCT as indicated by the smaller mean absolute error in CT numbers (28.7 ± 7.1 HU versus 38.8 ± 19.9 HU/53.2 ± 5.5 HU;P≤ 0.012) and higher Dice similarity of the internal gas regions (0.722 ± 0.088 versus 0.180 ± 0.098/0.659 ± 0.129;P≤ 0.002). Accordingly, the hybrid method resulted in more accurate proton range for the beams intersecting gas pockets (11 fields in 6 patients) than the individual methods (the 90th percentile error in 80% distal fall-off, 1.8 ± 0.6 mm versus 6.5 ± 7.8 mm/3.7 ± 1.5 mm;P≤ 0.013). The gamma passing rates also showed a significant dosimetric advantage by the hybrid method (99.7 ± 0.8% versus 98.4 ± 3.1%/98.3 ± 1.8%;P≤ 0.007).Significance. The hybrid method significantly improved the accuracy of sCT and showed promises in CBCT-based proton range verification and adaptive replanning of abdominal/pelvic proton therapy even when gas pockets are present in the beam path.

Multifaceted mirror array illuminator for fluorescence excitation-scanning spectral imaging microscopy

SIGNIFICANCE

Hyperspectral imaging (HSI) technologies offer great potential in fluorescence microscopy for multiplexed imaging, autofluorescence removal, and analysis of autofluorescent molecules. However, there are also associated trade-offs when implementing HSI in fluorescence microscopy systems, such as decreased acquisition speed, resolution, or field-of-view due to the need to acquire spectral information in addition to spatial information. The vast majority of HSI fluorescence microscopy systems provide spectral discrimination by filtering or dispersing the fluorescence emission, which may result in loss of emitted fluorescence signal due to optical filters, dispersive optics, or supporting optics, such as slits and collimators. Technologies that scan the fluorescence excitation spectrum may offer an approach to mitigate some of these trade-offs by decreasing the complexity of the emission light path.

AIM

We describe the development of an optical technique for hyperspectral imaging fluorescence excitation-scanning (HIFEX) on a microscope system.

APPROACH

The approach is based on the design of an array of wavelength-dependent light emitting diodes (LEDs) and a unique beam combining system that uses a multifurcated mirror. The system was modeled and optimized using optical ray trace simulations, and a prototype was built and coupled to an inverted microscope platform. The prototype system was calibrated, and initial feasibility testing was performed by imaging multilabel slide preparations.

RESULTS

We present results from optical ray trace simulations, prototyping, calibration, and feasibility testing of the system. Results indicate that the system can discriminate between at least six fluorescent labels and autofluorescence and that the approach can provide decreased wavelength switching times, in comparison with mechanically tuned filters.

CONCLUSIONS

We anticipate that LED-based HIFEX microscopy may provide improved performance for time-dependent and photosensitive assays.

Galactic cosmic ray simulation at the NASA space radiation laboratory - Progress, challenges and recommendations on mixed-field effects

For missions beyond low Earth orbit to the moon or Mars, space explorers will encounter a complex radiation field composed of various ion species with a broad range of energies. Such missions pose significant radiation protection challenges that need to be solved in order to minimize exposures and associated health risks. An innovative galactic cosmic ray simulator (GCRsim) was recently developed at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). The GCRsim technology is intended to represent major components of the space radiation environment in a ground analog laboratory setting where it can be used to improve understanding of biological risks and serve as a testbed for countermeasure development and validation. The current GCRsim consists of 33 energetic ion beams that collectively simulate the primary and secondary GCR field encountered by humans in space over the broad range of particle types, energies, and linear energy transfer (LET) of interest to health effects. A virtual workshop was held in December 2020 to assess the status of the NASA baseline GCRsim. Workshop attendees examined various aspects of simulator design, with a particular emphasis on beam selection strategies. Experimental results, modeling approaches, areas of consensus, and questions of concern were also discussed in detail. This report includes a summary of the GCRsim workshop and a description of the current status of the GCRsim. This information is important for future advancements and applications in space radiobiology.

Physicochemical stability of carmustine-containing medicinal products after reconstitution and after dilution to ready-to-administer infusion solutions stored refrigerated or at room temperature

INTRODUCTION

The aim of this study was to determine and compare the physicochemical stability of two carmustine-containing medicinal products licensed and marketed in Europe as Carmustin Obvius (Medac GmbH) and Carmubris (Tillomed Pharma GmbH). Reconstituted stock solutions and diluted ready-to-administer infusion solutions of the two products were investigated.

METHODS

Reconstituted carmustine stock solutions (3.3 mg/mL) and ready-to-administer infusion solutions (0.2 mg/mL, 1.0 mg/mL) prepared in prefilled 5% glucose injection solution PP/PE bags were stored at 22°C or 2-8°C over a maximum period of 66 hours protected from light. Samples were taken immediately after reconstitution or dilution and after 3.5, 6, 8.5 and 11 hours when stored at 22°C or after (12), 24, 48 and 60 hours when stored at 2-8°C, followed by 3- and 6-hour storage at 22°C (60+3 hours, 60+6 hours). Physicochemical stability was determined by reversed-phase high-performance liquid chromatography with UV detection, measurement of pH, osmolarity and inspection for visible particles or colour changes.

RESULTS

Carmustin Obvius and Carmubris reconstituted stock solutions were physicochemically stable for at least 48 hours when stored at 2-8°C. Carmustin Obvius and Carmubris infusion solutions 0.2 mg/mL were physicochemically stable for at least 8.5 hours and 60 hours when stored at 22°C and 2-8°C, respectively. After subsequent storage of the 60-hour refrigerated test solutions for 3 hours at 22°C, the carmustine concentrations averaged the 90% limit and fell below the 90% limit after 6 hours. Carmustin Obvius infusion solutions 1.0 mg/mL were physicochemically stable for at least 8.5 hours when stored at 22°C and for 60 hours when stored at 2-8°C.

CONCLUSION

According to the physicochemical stability data, the shelf life (95% limit) of the refrigerated stock solutions is 48 hours and the shelf life (90% limit) of ready-to-administer infusion solutions (0.2 mg/mL, 1.0 mg/mL) is 60 hours at 2-8°C or 8.5 hours at 22°C under light protection. These results facilitate the use of both medicinal products in a pharmacy-based centralised cytotoxic preparation unit.

B-Cell Reconstitution After Autologous Hematopoietic Stem Cell Transplantation in Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Autologous hematopoietic stem cell transplantation (aHSCT) is increasingly used to treat aggressive forms of multiple sclerosis (MS). This procedure is believed to result in an immune reset and restoration of a self-tolerant immune system. Immune reconstitution has been extensively studied for T cells, but only to a limited extent for B cells. As increasing evidence suggests an important role of B cells in MS pathogenesis, we sought here to better understand reconstitution and the extent of renewal of the B-cell system after aHSCT in MS.

METHODS

Using longitudinal multidimensional flow cytometry and immunoglobulin heavy chain (IgH) repertoire sequencing following aHSCT with BCNU + Etoposide + Ara-C + Melphalan anti-thymocyte globulin, we analyzed the B-cell compartment in a cohort of 20 patients with MS in defined intervals before and up to 1 year after aHSCT and compared these findings with data from healthy controls.

RESULTS

Total B-cell numbers recovered within 3 months and increased above normal levels 1 year after transplantation, successively shifting from a predominantly transitional to a naive immune phenotype. Memory subpopulations recovered slowly and remained below normal levels with reduced repertoire diversity 1 year after transplantation. Isotype subclass analysis revealed a proportional shift toward IgG1-expressing cells and a reduction in IgG2 cells. Mutation analysis of IgH sequences showed that highly mutated memory B cells and plasma cells may transiently survive conditioning while the analysis of sequence cluster overlap, variable (IGHV) and joining (IGHJ) gene usage and repertoire diversity suggested a renewal of the late posttransplant repertoire. In patients with early cytomegalovirus reactivation, reconstitution of naive and memory B cells was delayed.

DISCUSSION

Our detailed characterization of B-cell reconstitution after aHSCT in MS indicates a reduced reactivation potential of memory B cells up to 1 year after transplantation, which may leave patients susceptible to infection, but may also be an important aspect of its mechanism of action.

Regulation of water access, storage, separation and release of drugs from the carbon nanotube functionalized by cytosine rich DNA fragments

We found that carmustine can be stored in the carbon nanotube (CNT) interior for a long time due to hydrophobic interactions. The access of water to carmustine phase in the CNT interior can be controlled by the state of cytosine rich DNA fragments covalently bound to the CNT tips and to the presence of doxorubicin molecules intercalated within bundles of DNA fragments. More effective control of water access and subsequent decomposition of carmustine due to the contact with water was observed when some small amount of doxorubicin molecules cork the CNT ends. Our analysis shows that carmustine decomposition products naturally separate when decomposition occurs within the CNT. The alkylating agent, chloroethyl carbonium cation, spontaneously escapes from the CNT but the carbamylation agent, chloroethyl isocyanate, is still kept within the nanotube interior. The separation process and release of the alkylating agent needs uncorking the nanotube by doxorubicin molecules. The latter process is likely to occur spontaneously at acidic pH when intercalation of doxorubicin within the DNA fragments becomes ineffective. The features of the proposed molecular model, obtained from molecular dynamics simulations, can be beneficial in design of novel smart drugs carriers to a tumor microenvironment revealing the reduced extracellular pH.

Supramolecular Hydrogel Based Post-Surgical Implant System for Hydrophobic Drug Delivery Against Glioma Recurrence

Purpose

The brain, protected by the cranium externally and the blood–brain barrier (BBB) internally, poses challenges in chemotherapy of aggressive brain tumors. Maximal tumor resection followed by radiation and chemotherapy is the standard treatment protocol; however, a substantial number of patients suffer from recurrence. Systemic circulation of drugs causes myelodysplasia and other side effects. To address these caveats, we report facile synthesis of a polyester-based supramolecular hydrogel as a brain biocompatible implant for in situ delivery of hydrophobic drugs.

Methods

Polycaprolactone-diol (PCL) was linked to polyethyleneglycol-diacid (PEG) via an ester bond. In silico modeling indicated micelle-based aggregation of PCL-PEG co-polymer to form a supramolecular hydrogel. Brain biocompatibility was checked in Sprague Dawley rat brain cortex with MRI, motor function test, and histology. Model hydrophobic drugs carmustine and curcumin entrapment propelled glioma cells into apoptosis-based death evaluated by in vitro cytotoxicity assays and Western blot. In vivo post-surgical xenograft glioma model was developed in NOD-SCID mice and evaluated for efficacy to restrict aggressive regrowth of tumors.

Results

20% (w/v) PCL-PEG forms a soft hydrogel that can cover the uneven and large surface area of a tumor resection cavity and maintain brain density. The PCL-PEG hydrogel was biocompatible, and well-tolerated upon implantation in rat brain cortex, for a study period of 12 weeks. We report for the first time the combination of carmustine and curcumin entrapped as model hydrophobic drugs, increasing their bioavailability and yielding synergistic apoptotic effect on glioma cells. Further in vivo study indicated PCL-PEG hydrogel with a dual cargo of carmustine and curcumin restricted aggressive regrowth post-resection significantly compared with control and animals with intravenous drug treatment.

Conclusion

PCL-PEG soft gel-based implant is malleable compared with rigid wafers used as implants, thus providing larger surface area contact. This stable, biocompatible, supramolecular gel without external crosslinking can find wide applications by interchanging formulation of various hydrophobic drugs to ensure and increase site-specific delivery, avoiding systemic circulation.

Morphological and Calcium Signaling Alterations of Neuroglial Cells in Cerebellar Cortical Dysplasia Induced by Carmustine

Cortical dysplasias are alterations in the organization of the layers of the brain cortex due to problems in neuronal migration during development. The neuronal component has been widely studied in experimental models of cortical dysplasias. In contrast, little is known about how glia are affected. In the cerebellum, Bergmann glia (BG) are essential for neuronal migration during development, and in adult they mediate the control of fine movements through glutamatergic transmission. The aim of this study was to characterize the morphology and intracellular calcium dynamics of BG and astrocytes from mouse cerebellum and their modifications in a model of cortical dysplasia induced by carmustine (BCNU). Carmustine-treated mice were affected in their motor coordination and balance. Cerebellar dysplasias and heterotopias were more frequently found in lobule X. Morphology of BG cells and astrocytes was affected, as were their spontaneous [Ca²⁺]ⁱ transients in slice preparation and in vitro.

Biocompatible copolymer formulations to treat glioblastoma multiforme

The treatment for glioblastoma multiforme (GBM) has not changed for more than 20 years while the prognosis for the patients is still poor and most of them survive less than 1 year after diagnosis. The standard of care for GBM is comprised of surgical resection followed by radiotherapy and oral chemotherapy with temozolomide. The placement of carmustine wafers in the brain after tumour removal is added in cases of recurrent glioma. Significant research is underway to improve the GBM therapy outcome and patient quality of life. Biomaterials are in the front line of the research focus for new treatment options. Specially, biocompatible polymers have been proposed in hydrogel-based formulations aiming at injectable and localized therapies. These formulations can comprise many different pharmacological agents such as chemotherapeutic drugs, nanoparticles, cells, nucleic acids, and diagnostic agents. In this manuscript, we review the most recent formulations developed and tested both in vitro and in vivo using different types of hydrogels. Firstly, we describe three common types of thermo-responsive polymers addressing the advantages and drawbacks of their formulations. Then, we focus on formulations specifically developed for GBM treatment.

Loco-regional treatments in first-diagnosis glioblastoma: literature review on association between Stupp protocol and Gliadel

Loco-regional chemotherapy with carmustine wafers (Gliadel) positioned at surgery and followed by radiotherapy has been shown to prolong survival in first-diagnosis glioblastoma, as well as concomitant radiochemotherapy with temozolomide. The combination of Gliadel with the Stupp protocol has mostly been investigated in retrospective studies. objective of this study was to review the literature of efficacy and toxicities in patients with first-diagnosis glioblastoma treated with surgery, Gliadel, radiotherapy and temozolomide chemotherapy. The data in the literature regarding the combined use of Gliadel with chemotherapy, concomitant with radiotherapy and adjuvant temozolomide for glioblastoma was analyzed and compared. The results on survival and toxicity are summarized. The combination of Gliadel and radiotherapy with temozolomide is well tolerated and may increase survival without a substantial increase in major toxicity. However, only prospective comparative studies will be able to address the issue of true advantage in survival with this combination.

Pharmacokinetics of rituximab in patients with CD20 positive B-cell malignancies

BACKGROUND

In this study, we investigated the pharmacokinetics of rituximab in patients with CD20 positive non-Hodgkin lymphoma, to get more insight into the factors that influence the pharmacokinetics of rituximab. This may aid to understand variability of treatment outcome, in patients with a CD20 positive malignancy treated with rituximab.

METHODS

In this study, patients with a CD20 positive B-cell malignancy who were treated with rituximab containing regimens were included. Induction treatment schedules consisted of a combination of rituximab with chemotherapy for 4-8 cycles. Maintenance treatment consisted of a 2 or 3-monthly dose of 375 mg/m2 rituximab intravenously for 2 years. On the day of the treatment with rituximab, preinfusion blood samples were taken. Also, after the end of treatment, selected blood samples were taken. Rituximab levels were measured with a validated enzyme-linked immunosorbent assay (ELISA). An antigen binding assay was applied for determination of human-antibodies against chimeric-antibodies (HACAs).

RESULTS

Eight patients were on induction therapy. Rituximab levels of one patient on induction therapy remained very low after the first course. This patient had a chronic lymphoid leukemia with circulating tumor cells and a high tumor burden. Apart from one patient with mantle cell lymphoma, all patients on induction therapy had a complete response. Five patients were on maintenance therapy. Trough levels of 4 patients on three-monthly schedule maintenance therapy remained constant, with a median concentration of 6 mu g/mL (range 0.5-11.7 microg/mL). One patient had a relapse during his maintenance treatment. The elimination half-life at steady state of rituximab in all patients was estimated to be 19.2 (+/- 15.2%) days with a between-subject variability of 54%, indicating wide variability. Possible pharmacokinetic-pharmacodynamic relationship was observed as rituximab levels of the non-responders remained low compared to the rituximab levels of the responders. For all patients, concentration of HACAs remained below the quantification limit.

SUMMARY/CONCLUSION

Considerable inter-individual variability of rituximab levels was observed. Although the patient population was small, the results support the need for more research into the pharmacokinetics and factors that might influence the pharmacokinetic-pharmacodynamic relationships of rituximab in patients with non-Hodgkin lymphoma.

Comorbidities, not age, impact outcomes in autologous stem cell transplant for relapsed non-Hodgkin lymphoma

High-dose chemotherapy followed by autologous peripheral blood stem cell transplantation is a widely applied treatment for advanced non-Hodgkin lymphoma (NHL), but few studies have analyzed the tolerability and outcomes in older patients compared with younger patients treated in a homogeneous manner. We retrospectively reviewed 152 consecutive patients who underwent autologous stem cell transplantation (ASCT) following BEAM conditioning (carmustine, etoposide, cytarabine, and melphalan) for NHL from January 2000 through August 2004 at our institution. We compared 59 patients age > or =60 years and 93 patients age <60 years. Supportive care was identical for all patients. The frequency of comorbidities was similar between both groups. CD34+ cell doses, days to neutrophil recovery, and days to platelet count >20,000/mm3 were similar in younger and older patients, although days to platelet count >50,000/mm3 were longer in the older patients (median 30.0 days versus 22.5 days, P = .01). Patients over the age of 60 were more likely to develop grade III/IV mucositis than their younger counterparts (37.7% versus17.4%, P = .0063). Otherwise, the frequency of other grade III/IV toxicities were similar between younger and older patients. Treatment-related mortality (TRM) was similar between older and younger patients (8.5% versus 5.4%, P = .45). Although age was not associated with TRM, the Charlson Comorbidity Index Score was significantly correlated with TRM (P = .03). Median disease-free survival was similar between older and younger patients (21.8 months versus 29.9 months, P = .93), as was overall survival (OS) (47.7 months versus 62.5 months, P = .20). After controlling for age, the Charlson Comorbidity Index Score influenced OS [P = .013]. Overall, our cohort of patients with NHL over the age of 60 who underwent ASCT following BEAM conditioning experienced toxicities and survival similar to their younger counterparts. Comorbidities significantly influenced TRM and OS in this retrospective cohort. Future study should focus on improving tolerability of conditioning and careful prospective evaluation of comorbidities and their association with outcomes.

Intracavitary chemotherapy (Gliadel) and oral low-dose etoposide for recurrent anaplastic ependymoma

Anaplastic ependymoma is associated with a higher incidence of tumor recurrence and its prognosis still remains unsatisfactory. Consolidated therapy for ependymoma includes surgery followed by focal radiotherapy when resection is incomplete. In the case of relapse treatment, options are limited especially for patients who have already received radiotherapy. We sought to establish the feasibility of administering low-dose oral etoposide (50 mg/m(2)/day for 21 days) in combination with the implantation of intracavitary carmustine (BCNU) wafers (Gliadel) at the gross total resection for achieving synergistic treatment in three children affected by recurrent anaplastic ependymoma. All patients had Karnofsky performance scale (KPS) scores >80%. The therapy was tolerated safely and well in all patients without any post-surgery complications. After BCNU wafer implantation, all patients achieved radiological and clinical stabilization for an average period of 3 months. Two patients relapsed after 4 months as shown in brain MRIs. The other patient went to progression two months after the Gliadel implantation. This multimodal approach was not effective for the treatment of refractory anaplastic ependymoma and further studies are required in order to define the role of the combination of multidrug systemic chemotherapy with BCNU wafer implantation in children with high-risk brain tumors.

Neuroprotective effects of melatonin upon the offspring cerebellar cortex in the rat model of BCNU-induced cortical dysplasia

Cortical dysplasia is a malformation characterized by defects in proliferation, migration and maturation. This study was designed to evaluate the alterations in offspring rat cerebellum induced by maternal exposure to carmustine-[1,3-bis (2-chloroethyl)-1-nitrosoure] (BCNU) and to investigate the effects of exogenous melatonin upon cerebellar BCNU-induced cortical dysplasia, using histological and biochemical analyses. Pregnant Wistar rats were assigned to five groups: intact-control, saline-control, melatonin-treated, BCNU-exposed and BCNU-exposed plus melatonin. Rats were exposed to BCNU on embryonic day 15 and melatonin was given until delivery. Immuno/histochemistry and electron microscopy were carried out on the offspring cerebellum, and levels of malondialdehyde and superoxide dismutase were determined. Histopathologically, typical findings were observed in the cerebella from the control groups, but the findings consistent with early embryonic development were noted in BCNU-exposed cortical dysplasia group. There was a marked increase in the number of TUNEL positive cells and nestin positive cells in BCNU-exposed group, but a decreased immunoreactivity to glial fibrillary acidic protein, synaptophysin and transforming growth factor beta1 was observed, indicating a delayed maturation, and melatonin significantly reversed these changes. Malondialdehyde level in BCNU-exposed group was higher than those in control groups and melatonin decreased malondialdehyde levels in BCNU group (P<0.01), while there were no significant differences in the superoxide dismutase levels between these groups. These data suggest that exposure of animals to BCNU during pregnancy leads to delayed maturation of offspring cerebellum and melatonin protects the cerebellum against the effects of BCNU.

[Changes of expression of cation-chloride cotransporter genes in hippocampus of cortical dysplasia: experiment with rat]

OBJECTIVE

To investigate the roles of cation-chloride cotransporters-Na, K, 2Cl(-) cotransporter-1 (NKCC1) and K(+)-Cl(-) cotransporter-2 (KCC(2)) in the epileptogenesis of cortical dysplasia.

METHODS

Six pregnant SD rats were given intraperitoneal injection of 1-3-bis-chloroethyl-nitrosourea (BCNU) on the embryonic day 17 (E17) and gave birth of 56 pups (experimental group) on the day P21. Five pregnant SD rats were given intraperitoneal injection of normal saline and gave birth of 48 pups (control group) on the day E21. Sixty days after birth the brains of 24 male pups in the experimental group and 22 male pups in the control group selected randomly were taken out to isolate the hippocampus. Cresyl-violet staining was applied to observe the histological alterations in the hippocampus. RT-PCR was used to detect the mRNA expression of NKCC1 and KCC2.

RESULTS

Cresyl-violet staining revealed heterotopic cell clusters within the hippocampus. RT-PCR showed that the ratio of NKCC1 to beta-actin of the experimental group was 0.70 +/- 0.13, significantly higher than that of the control group (0.48 +/- 0.09, P < 0.01); while the ratio of KCC2 to beta-actin of the experimental group was 0.54 +/- 0.10, significantly lower than that of the control group (0.80 +/- 0.15, P < 0.01).

CONCLUSION

The upregulation of NKCC1 mRNA and the concomitant downregulation of KCC2 mRNA may be deeply related to the mechanism of epileptogenicity in cortical dysplasias.

[What type of adjuvant chemotherapy should be proposed for the initial treatment of glioblastoma?]

Carmustine wafers (Gliadel) and temozolomide (Temodal) were recently approved for initial management of glioblastoma. Gliadel) is a polymer wafer containing carmustine. These wafers are designed to be placed in the surgical cavity after glioblastoma resection to deliver local chemotherapy. This treatment is intended for tumors for which gross total resection is possible. Temozolomide is administered concomitantly with radiotherapy for six weeks followed by six cycles of adjuvant temozolomide (EORTC 26981, also known as "Stupp's protocol"). Temozolomide administered according to this protocol produced a median survival benefit of 2 months in glioblastomas, and carmustine a similar benefit in high-grade gliomas. The two-year survival rate was 26.5% with radiotherapy plus temozolomide compared with 10.4% with radiotherapy alone. In patients with complete resection, two-year survival reached 38%. These two new treatments are essentially intended for patients younger than 70 years and with a Karnofsky index>70. Ongoing studies are evaluating the possible value of combining these two treatments.

A phase I trial of surgery, Gliadel wafer implantation, and immediate postoperative carboplatin in combination with radiation therapy for primary anaplastic astrocytoma or glioblastoma multiforme

Two types of chemotherapy used in the treatment of patients with malignant glioma are carboplatin and Gliadel wafer [(3.85% 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU)]. To date there have been no published data examining their concurrent use in this disease. The purpose of this study was to evaluate combination chemotherapy with Gliadel wafer and carboplatin in patients with high-grade, malignant glioma. In this prospective phase I study, 16 patients underwent surgery, Gliadel wafer implantation (up to 8 wafers), intravenous carboplatin given postoperatively (day 3 or 4) at a dose escalation range of area under the curve (AUC)=2-6, and external beam radiation. Median age was 55 years (range 27-66 years). Fourteen (88%) patients had glioblastoma multiforme and 2 (12%) had anaplastic astrocytoma. Performance status was as follows: Eastern Cooperative Oncology Group (ECOG)=0 (2 patients), ECOG=1 (13 patients), and ECOG=2 (2 patients). Three patients were treated at each dosing level (AUC=2-6), and 4 patients were treated at an AUC=5. Carboplatin was administered to all patients by postoperative day 4. Radiation was begun on day 14-36. No grade 3 or 4 toxicities were noted in this study. Median progression-free and overall survival was 266 and 679 days, respectively. We conclude that administering systemic carboplatin is safe and well tolerated in the postoperative period immediately following resection and implantation of Gliadel wafer for the treatment of malignant glioma. Further evaluation in a phase II setting, at maximal carboplatin dose to establish potential efficacy, with this combination is warranted.

Cloning and expression of canine O6-methylguanine-DNA methyltransferase in target cells, using gammaretroviral and lentiviral vectors

The human O(6)-methylguanine-DNA methyltransferase (MGMT) gene and its mutants have been used for in vivo selection of transduced hematopoietic stem cells with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) alone or in combination with O(6)-benzylguanine (BG). To allow similar in vivo selection in dogs, without the risk of inducing an immune response, we have cloned the canine MGMT drug resistance gene. Comparison of canine and human MGMT-coding regions indicates that there is about 62% amino acid identity and 78% similarity between the two MGMTs. The canine MGMT is also longer, by nine amino acids. Proline at position 140 and the surrounding amino acids of the human MGMT are highly conserved in the canine sequence. To determine whether mutation of the proline residue at position 144 to lysine in the canine MGMT would provide a similar advantage for selection of transduced cells as the human mutant, Moloney murine leukemia virus and human immunodeficiency type 1 vectors encoding the corresponding mutant MGMT were created and used to express separately canine and human MGMTs in cultured cells. Drug resistance assays using BCNU alone or BCNU with BG demonstrated that the wild-type and mutant canine MGMTs provided resistance to the selection agents that was comparable to the human MGMT counterparts.

A hybrid form of myeloid/NK-cell acute leukemia and myeloid/NK-cell precursor acute leukemia

Natural killer (NK)-cell leukemia/lymphoma is a rare entity that has been defined only in recent years. In the Revised European-American Lymphoma and World Health Organization classifications, only the mature NK-cell malignancies are included. However, at least 3 types of precursor NK-cell neoplasms have been reported in the literature. These include myeloid/NK-cell acute leukemia, myeloid/NK-cell precursor acute leukemia, and blastic NK-cell lymphoma/leukemia. These leukemias are characterized by the presence of blasts, which express CD56, in the peripheral blood, bone marrow, lymph nodes, and/or extranodal tissues. We report a case that is morphologically consistent with myeloid/NK-cell acute leukemia but immunologically is myeloid/NK-cell precursor acute leukemia. This case is unique in its cutaneous presentation without involvement of the peripheral blood. Extensive flow cytometric studies were performed on the skin biopsy and bone marrow aspirate specimens, which included many markers that had not been tested before in these entities. The clinical implications of these findings are discussed.

High-dose therapy in diffuse large cell lymphoma: results and prognostic factors in 452 patients from the GEL-TAMO Spanish Cooperative Group

BACKGROUND

The purpose of this study was to analyse the results and prognostic factors influencing overall survival (OS) and disease-free survival (DFS) in 452 patients diagnosed with diffuse large cell lymphomas (DLCL) treated with high-dose therapy (HDT) included in the Grupo Español de Linfomas/Trasplante Autólogo de Médula Osea (GEL-TAMO) Spanish registry.

PATIENTS AND METHODS

At transplantation, median age was 42 years (range 15-73), 146 patients (32%) were transplanted in first complete remission (1st CR), 19% in second CR (2nd CR) and 47% had active disease: sensitive disease in 157 (35%) patients [95 were in first partial remission (1st PR) and 62 in second PR (2nd PR)] and refractory disease in 55 (12%) patients. Age-adjusted International Prognostic Index (IPI) was 2 or 3 in 51 patients (12%). Conditioning regimen consisted of BEAM (carmustine, etoposide, cytarabine and melphalan) in 39% of patients, BEAC (carmustine, etoposide, cytarabine and cyclophosphamide) in 33%, CBV (carmustine, etoposide and cyclophosphamide) in 10% and cyclophosphamide plus total body irradiation (TBI) in 12%.

RESULTS

Estimated overall survival (OS) and disease-free survival (DFS) at 5 years were 53% and 43%, respectively. The transplant-related mortality was 11% (53 cases). By multivariate analysis three variables significantly influenced OS and DFS: number of protocols to reach 1st CR, disease status at transplant and TBI in the conditioning regimen. Age-adjusted IPI at transplantation also influenced OS.

CONCLUSIONS

Prolonged OS and DFS can be achieved in patients with DLCL after HDT and our results suggest that the best line of chemotherapy should be used up-front in patients considered as candidates for HDT in order to obtain an early CR. Resistant patients are not good candidates for HDT and they should be offered newer strategies. Finally, polichemotherapy conditioning regimens offer better results compared with TBI.

Autologous stem cell transplantation for Hodgkin's lymphoma: results and prognostic factors in 51 high-risk patients

Autologous stem cell transplantation (ASCT) is largely employed in primary resistant or recurrent Hodgkin's Lymphoma (HL), while its role early in the course of the disease is still controversial. Our purpose was to analyse the results of 51 high-risk HL patients autografted at our Institution and the role of possible prognostic risk factors for the outcome. Twelve (23.5%) patients were in complete remission at transplant and were transplanted as having an high risk disease; 20 (39.5%) patients were in partial response and 19 (37.0%) were transplanted as primary induction failure. At a median time of 38 (6-111) months from ASCT, 36 (70.5%) patients are alive in complete remission, 8 (15.5%) patients are alive with disease and 7 (14.0%) died for progression. Thirty out of 32 (94.0%) patients transplanted with responsive disease (either complete or partial response) are alive without disease. Six out of 19 (32.0%) patients transplanted with resistant disease are alive in complete remission. The overall survival of the entire population is 77.0% at 60 (14-151) months from diagnosis. Disease free survival of the 22 patients that achieved a complete remission after ASCT (16 in partial response and 6 with resistant disease) is 100%. In our experience, more than 90% of patients transplanted with responsive but high risk disease, seem achieving and maintaining a durable complete remission, and more than 30.0% of patients submitted to ASCT with refractory disease can be potentially rescued by transplant.

Patients with mantle-cell lymphoma relapsing after autologous stem cell transplantation may be rescued by allogeneic transplantation

Two patients with disseminated mantle-cell lymphoma relapsed 24 and 13 months, respectively, after high-dose chemotherapy and autologous stem cell transplantation (autoSCT). Both patients had an HLA-identical sibling and received an allogeneic stem cell transplant (alloSCT) 32 and 18 months after autologous transplant, after conditioning with fractionated 12 Gy total body irradiation plus cyclophosphamide 120 mg/kg. They are both alive and in complete remission 24 months after transplant. Both patients have developed chronic graft-versus-host disease and their Karnofsky performance status is 90%. AlloSCT may offer a useful approach in a subgroup of patients with mantle-cell lymphoma who have relapsed after autologous transplantation.

Dementia improvement with cytotoxic chemotherapy. A case of Alzheimer disease and multiple myeloma

OBJECTIVES

To describe a patient with Alzheimer disease and multiple myeloma (with Bence Jones proteinuria) with improvement of both conditions following cytotoxic chemotherapy, and to present issues related to the pathogenesis and management of Alzheimer disease.

DESIGN

Report of a case.

SETTING

Progressive dementia and myeloma developed in a 64-year-old man. Cytotoxic chemotherapy for the myeloma resulted in maintained improvement of the dementia. Clinical, neuropsychological, pathological, and laboratory data are presented.

MAIN OUTCOME AND RESULTS

For 2 years, vincristine sulfate, carmustine, melphalan, cyclophosphamide, and prednisone were administered cyclically, and the patient's dementia and lambda light chain production improved. Severe dementia recurred before death and cessation of therapy, although light chain production remained decreased.

CONCLUSION

Dementia improvement with cytotoxic (ie, immunosuppressive, anti-inflammatory) therapy may offer insight into the pathogenesis and management of Alzheimer disease.

Intensified and high-dose chemotherapy with granulocyte colony-stimulating factor and autologous stem-cell transplantation support as first-line therapy in high-risk diffuse large-cell lymphoma

PURPOSE

In our previous study with MACOPB, we identified a high-risk group of patients with a poor 3-year survival rate of 29%. These patients were defined as having at diagnosis advanced-stage disease with high tumor burden (TB) and elevated lactate dehydrogenase (LDH) level or bone marrow (BM) involvement. A novel therapeutic scheme was investigated to improve the outcome of these patients.

PATIENTS AND METHODS

Fifty patients with high-risk diffuse large-cell lymphoma (DLCL) were enrolled. The therapeutic scheme includes three phases: induction with 8 weeks of MACOPB; intensification with a 3-day course of mitoxantrone 8 mg/m2 plus high-dose cytarabine (HDARA-C) 2 g/m2 every 12 hours plus dexamethasone 4 mg/m2 every 12 hours (MAD protocol) and granulocyte colony-stimulating factor (G-CSF) 5 microg/kg on days 4 to 17 to harvest peripheral-blood progenitor cells (PBPC); consolidation with carmustine (BCNU), etoposide, ARA-C, and melphalan (BEAM) regimen; plus autologous stem-cell transplantation (ASCT) with PBPC, marrow, or both.

RESULTS

Thirty-six patients (72%) achieved a complete response (CR), 11 (22%) showed no response (NR), and three (6%) died of toxicity. Among the 22 PRs or NRs after the induction phase, 56% of patients achieved a CR with subsequent intensified therapy. With a median follow-up duration of 32 months, the overall survival and failure-free survival rates were 56% and 50%, respectively. The disease-free survival rate is 69% at 32 months. Leukapheresis after MAD and G-CSF yielded a median of 32 x 10(6)/kg CD34+ cells and 80 x 10(4)/kg granulocyte-macrophage colony-forming units (CFU-GM). Thirty-nine patients were autografted and 11 did not undergo ASCT: six because of disease progression, four due to toxicity, and one because of patient refusal. The median times to achieve engrafment were 11 days (range, 7 to 19) to a neutrophil count greater than 0.5 x 10(9)/L and 12 days (range, 8 to 60) to a platelet count greater than 50 x 10(9)/L.

CONCLUSION

This sequential scheme with intensified and high-dose chemotherapy with ASCT is feasible with moderate toxicity and may improve the outcome in high-risk DLCL.

IN VIVO ANTIVIRAL ACTIVITY OF 1,3-BIS(2-CHLOROETHYL)-1-NITROSOUREA

A prolongation in the lives of Swiss mice inoculated intracerebrally with lymphocytic choriomeningitis virus (LCM) was observed after treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A variety of treatment schedules, including therapy once or twice daily up to 17 days and single treatments at various times after virus inoculation, were employed. Virus titers ranging to greater than 10(4) were detected in the blood and brains of surviving drug-treated animals. In three comparative studies in which different treatment schedules were used, BCNU was shown to exert a protective effect approximately equal to that of methotrexate in LCM virus-infected mice. Tests were also carried out to investigate the activity of BCNU in mice experimentally infected with eastern equine encephalomyelitis (EEE) virus, western equine encephalomyelitis virus, Semliki Forest (SF) virus, herpes simplex virus, influenza virus strain PR8, vaccinia virus strain WR, Rous sarcoma virus, Friend leukemia virus (FLV), and poliovirus. Slight increases in life span were observed in the treated EEE, SF, and influenza PR8 virus-infected animals. Significant reduction in splenomegaly in FLV-infected animals treated with BCNU was demonstrated. The possible mechanisms of LCM virus inhibition by BCNU, on the basis of these and other studies, were postulated to be either specific antiviral activity or inhibition of "lethal" immune response to the LCM virus. Each of these postulates is discussed.

High-dose therapy with peripheral blood progenitor cell transplantation in low-grade non-Hodgkin's lymphoma

It was the objective of our study to evaluate the efficacy of a sequential high-dose therapy with peripheral blood progenitor cell (PBPC) support in patients with low-grade non-Hodgkin's lymphoma (NHL). Since July 1991, 48 patients (23 male/25 female) with a median age of 43 years (range 26-55) were included in the study. At the time of entry, 28 patients were in first and seven in second or higher remission. Twelve patients had relapse of disease and one patient had tumor progression. PBPC were collected during granulocyte colony-stimulating factor (G-CSF)-enhanced leukocyte recovery following treatment with high-dose cytarabine and mitoxantrone (HAM). A median of two leukaphereses (range 2-7) resulted in 6.9 x 10(6) CD34+ cells/kg (median, range 2.1 x 10(6)-38.8 x 10(6)). A comparison was made between the harvests obtained from patients in first remission and those from patients in second remission, in relapse or progressive disease. Patients mobilized in first remission tended to have a greater collection efficiency for CD34+ cells comprising a significantly greater proportion of more primitive CD34+/Thy-1+ progenitor cells. Conversely, leukapheresis (LP) products collected during first remission contained a significantly smaller proportion of CD34+/CD45RA+ cells and CD34+/c-kit+ cells, subsets which reflect a more differentiated progenitor cell stage. Following high-dose therapy and PBPC autografting, the median time to reach platelets > or = 20 x 10(9)/l and neutrophils > or = 0.5 x 10(9)/l and 12 and 13 days, respectively. Two patients died of treatment-related toxic organ failure. Thirty-nine patients are alive in remission after a median follow-up time of 15 months (range 1-31), while seven patients relapsed between 5 and 29 months post-transplantation. Except for one patient autografted in first remission, the patients with relapse had a history of previous relapse or progressive disease. Since the probability of disease-free survival appears to be related to the disease status at the time of autografting, PBPC-supported high-dose therapy including total body irradiation should be investigated further for patients with low-grade NHL while they are in first remission.