Focal Prostate Stereotactic Body Radiation Therapy With Correlative Pathological and Radiographic-Based Treatment Planning

Introduction

Advances in multiparametric MRI (mpMRI) combining anatomic and functional imaging can accurately identify foci of adenocarcinoma within the prostate, offering the possibility of partial gland therapy. We performed tandem prospective pilot trials to investigate the feasibility of focal prostate SBRT (f-SBRT) based on correlating diagnostic mpMRI and biopsies with confirmatory pathology in treatment planning.

Materials and Methods

Patients with pathologic focal Gleason 6–7 disease and a corresponding PIRADS 4–5 lesion on mpMRI underwent targeted and comprehensive biopsies using MRI/ultrasound fusion under electromagnetic sensor navigation. After rigorous analysis for imaging biopsy concordance, five of 18 patients were eligible to proceed to f-SBRT. Chi-squared test was used for differences from expected outcomes, and concordance was estimated with binomial distribution theory and Wilson’s method.

Results

Six patients had Gleason 6 and 12 had Gleason 3 + 4 disease (mean PSA: 5.8 ng/ml, range: 2.2–8.4). Absolute concordance was 43.8% (95% CI: 0.20, 0.64). Patterns of discordance included additional sites of ipsilateral disease, bilateral disease, and negative target. Five were upstaged to a new NCCN risk category necessitating treatment escalation. The five patients with concordant pathology completed three-fraction f-SBRT with sparing of the surrounding normal structures (including contralateral neurovascular bundle), with no reported grade 2+ toxicities and favorable PSA responses (mean: 41% decrease).

Conclusions

On our pilot trials of f-SBRT planning using rigorous imaging and pathology concordance, image-guided confirmatory biopsies frequently revealed additional disease, suggesting the need for caution in partial-gland therapy. For truly focal disease, f-SBRT provided excellent dosimetry, minimal toxicity, and encouraging biochemical response. Clinical Trial Registration: www.clinicaltrials.gov, NCT02681614; NCT02163317.

Transforming UTE-mDixon MR Abdomen-Pelvis Images Into CT by Jointly Leveraging Prior Knowledge and Partial Supervision

Computed tomography (CT) provides information for diagnosis, PET attenuation correction (AC), and radiation treatment planning (RTP). Disadvantages of CT include poor soft tissue contrast and exposure to ionizing radiation. While MRI can overcome these disadvantages, it lacks the photon absorption information needed for PET AC and RTP. Thus, an intelligent transformation from MR to CT, i.e., the MR-based synthetic CT generation, is of great interest as it would support PET/MR AC and MR-only RTP. Using an MR pulse sequence that combines ultra-short echo time (UTE) and modified Dixon (mDixon), we propose a novel method for synthetic CT generation jointly leveraging prior knowledge as well as partial supervision (SCT-PK-PS for short) on large-field-of-view images that span abdomen and pelvis. Two key machine learning techniques, i.e., the knowledge-leveraged transfer fuzzy c-means (KL-TFCM) and the Laplacian support vector machine (LapSVM), are used in SCT-PK-PS. The significance of our effort is threefold: 1) Using the prior knowledge-referenced KL-TFCM clustering, SCT-PK-PS is able to group the feature data of MR images into five initial clusters of fat, soft tissue, air, bone, and bone marrow. Via these initial partitions, clusters needing to be refined are observed and for each of them a few additionally labeled examples are given as the partial supervision for the subsequent semi-supervised classification using LapSVM; 2) Partial supervision is usually insufficient for conventional algorithms to learn the insightful classifier. Instead, exploiting not only the given supervision but also the manifold structure embedded primarily in numerous unlabeled data, LapSVM is capable of training multiple desired tissue-recognizers; 3) Benefiting from the joint use of KL-TFCM and LapSVM, and assisted by the edge detector filter based feature extraction, the proposed SCT-PK-PS method features good recognition accuracy of tissue types, which ultimately facilitates the good transformation from MR images to CT images of the abdomen-pelvis. Applying the method on twenty subjects' feature data of UTE-mDixon MR images, the average score of the mean absolute prediction deviation (MAPD) of all subjects is 140.72 ± 30.60 HU which is statistically significantly better than the 241.36 ± 21.79 HU obtained using the all-water method, the 262.77 ± 42.22 HU obtained using the four-cluster-partitioning (FCP, i.e., external-air, internal-air, fat, and soft tissue) method, and the 197.05 ± 76.53 HU obtained via the conventional SVM method. These results demonstrate the effectiveness of our method for the intelligent transformation from MR to CT on the body section of abdomen-pelvis.

Final results of a dose escalation protocol of stereotactic body radiotherapy for poor surgical candidates with localized renal cell carcinoma

BACKGROUND AND PURPOSE

We previously demonstrated the safety of doses up to 48 Gy in 4 fractions with stereotactic body radiotherapy (SBRT) in poor surgical candidates with localized renal cell carcinoma (RCC). In an additional expansion cohort, we aimed to assess the safety of further dose escalation to 48-60 Gy in 3 fractions.

MATERIAL AND METHODS

Patients were required to have localized RCC and be poor surgical candidates due to medical comorbidities. Dose-limiting toxicity (DLT) was defined as acute (<180 days) grade ≥3 gastrointestinal/genitourinary toxicity by CTCAEv4. Tumor response was assessed using RECIST 1.1 criteria measurements every 6 months for 3 years and optional percutaneous biopsy.

RESULTS

Groups of 4, 4, and 3 patients received 48, 54, and 60 Gy in 3 fractions, respectively from 2012 to 2016. Median follow-up was 34.3 months. Zero DLTs were observed. Acute toxicities were limited to grade 1 fatigue and nausea in 45.5% and 18.1%. Late grade 2+ and grade 3+ possibly treatment-related events occurred in 18.1% and 9.1%, respectively. Three-year local control was 90% by RECIST 1.1 criteria. Five of 5 post-treatment biopsies in the expansion cohort were positive by Hematoxylin and Eosin staining. Three of the 5 patients with positive biopsies have been observed for 1.2-3.9 years without evidence of progression.

CONCLUSION

Dose escalation to 60 Gy in 3 fractions was achieved without DLTs. Favorable local control rates were observed, and the interpretation of post-SBRT biopsies remains uncertain. Further studies comparing SBRT to percutaneous ablation for poor surgical candidates with RCC are warranted.

Adjusting to the new reality: Evaluation of early practice pattern adaptations to the COVID-19 pandemic

OBJECTIVE

We aim to define national practice patterns to assess current clinical practice, anticipated delays and areas of concern that potentially could lead to deviations from the normal standard of care.

METHODS

Anonymous surveys were emailed to members of the Society of Gynecologic Oncology (SGO). The spread of COVID-19 and its impact on gynecologic oncology care in terms of alterations to normal treatment patterns and anticipated challenges were assessed. The Wilcoxon rank sum test was performed to determine risk factors for COVID-19 infection.

RESULTS

We analyzed the responses of 331 gynecologic oncology providers. COVID-19 is present in 99.1% of surveyed communities with 99.7% reporting mitigation efforts in effect. The infection rate differs significantly between regions (p≪0.001) with the Northeast reporting the highest number of COVID-19 cases. Practice volume has dropped by 61.6% since the start of the pandemic with most cancellations being provider initiated. A majority of responders (52.8%) believed that ovarian cancer will be the most affected cancer by COVID-19. >94% of responders are proceeding with gynecologic cancer surgeries with exception of grade 1, endometrioid endometrial adenocarcinoma (36.3%). Surgical backlog (58.6%), delayed cancer diagnosis (43.2%) and re-establishing normal care with delayed patient (37.8%) were identified as the top 3 challenges after COVID-19 has abated.

CONCLUSIONS

COVID-19 is widespread and has radically altered normal practice patterns. Despite COVID-19 related concerns, most gynecologic oncology care is proceeding. However, the steep decline in clinical volume shows there is a large group of patients who are not being diagnosed or are deferring care.

mDixon-Based Synthetic CT Generation for PET Attenuation Correction on Abdomen and Pelvis Jointly Using Transfer Fuzzy Clustering and Active Learning-Based Classification

We propose a new method for generating synthetic CT images from modified Dixon (mDixon) MR data. The synthetic CT is used for attenuation correction (AC) when reconstructing PET data on abdomen and pelvis. While MR does not intrinsically contain any information about photon attenuation, AC is needed in PET/MR systems in order to be quantitatively accurate and to meet qualification standards required for use in many multi-center trials. Existing MR-based synthetic CT generation methods either use advanced MR sequences that have long acquisition time and limited clinical availability or use matching of the MR images from a newly scanned subject to images in a library of MR-CT pairs which has difficulty in accounting for the diversity of human anatomy especially in patients that have pathologies. To address these deficiencies, we present a five-phase interlinked method that uses mDixon MR acquisition and advanced machine learning methods for synthetic CT generation. Both transfer fuzzy clustering and active learning-based classification (TFC-ALC) are used. The significance of our efforts is fourfold: 1) TFC-ALC is capable of better synthetic CT generation than methods currently in use on the challenging abdomen using only common Dixon-based scanning. 2) TFC partitions MR voxels initially into the four groups regarding fat, bone, air, and soft tissue via transfer learning; ALC can learn insightful classifiers, using as few but informative labeled examples as possible to precisely distinguish bone, air, and soft tissue. Combining them, the TFC-ALC method successfully overcomes the inherent imperfection and potential uncertainty regarding the co-registration between CT and MR images. 3) Compared with existing methods, TFC-ALC features not only preferable synthetic CT generation but also improved parameter robustness, which facilitates its clinical practicability. Applying the proposed approach on mDixon-MR data from ten subjects, the average score of the mean absolute prediction deviation (MAPD) was 89.78±8.76 which is significantly better than the 133.17±9.67 obtained using the all-water (AW) method (p=4.11E-9) and the 104.97±10.03 obtained using the four-cluster-partitioning (FCP, i.e., external-air, internal-air, fat, and soft tissue) method (p=0.002). 4) Experiments in the PET SUV errors of these approaches show that TFC-ALC achieves the highest SUV accuracy and can generally reduce the SUV errors to 5% or less. These experimental results distinctively demonstrate the effectiveness of our proposed TFCALC method for the synthetic CT generation on abdomen and pelvis using only the commonly-available Dixon pulse sequence.

Comparative analysis for renal stereotactic body radiotherapy using Cyberknife, VMAT and proton therapy based treatment planning

PURPOSE

We conducted this dosimetric analysis to evaluate the feasibility of a multi-center stereotactic body radiation therapy (SBRT) trial for renal cell carcinoma (RCC) using different SBRT platforms.

MATERIALS/METHODS

The computed tomography (CT) simulation images of 10 patients with unilateral RCC previously treated on a Phase 1 trial at Institution 1 were anonymized and shared with Institution 2 after IRB approval. Treatment planning was generated through five different platforms aiming a total dose of 48 Gy in three fractions. These platforms included: Cyberknife and volumetric modulated arc therapy (VMAT) at institution 1, and Cyberknife, VMAT, and pencil beam scanning (PBS) Proton Therapy at institution 2. Dose constraints were based on the Phase 1 approved trial.

RESULTS

Compared to Cyberknife, VMAT and PBS plans provided overall an equivalent or superior coverage to the target volume, while limiting dose to the remaining kidney, contralateral kidney, liver, spinal cord, and bowel.

CONCLUSION

This dosimetric study supports the feasibility of a multi-center trial for renal SBRT using PBS, VMAT and Cyberknife.

3T multiparametric MRI-guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PURPOSE

To evaluate the role of 3T-MRI-guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter.

METHODS AND MATERIALS

We retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups.

RESULTS

Seventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D₉₀ (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D_2cc (Gy) for organs at risk was comparable. No Grades 3-4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively.

CONCLUSIONS

The mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.

Outcomes and toxicities in patients treated with definitive focal therapy for primary prostate cancer: systematic review

AIM

This systematic review summarizes the clinical data on focal therapy (FT) when used alone as definitive therapy for primary prostate cancer (PCa).

METHODS

The protocol is detailed in the online PROSPERO database, registration No. CRD42014014765. Articles evaluating any form of FT alone as a definitive treatment for PCa in adult male patients were included.

RESULTS

Of 10,419 identified articles, 10,401 were excluded, and thus leaving 18 for analysis. In total, 2288 patients were treated using seven modalities. The outcomes of FT in PCa seem to be similar to those observed with whole gland therapy and with fewer side effects.

CONCLUSION

Further research, including prospective randomized trials, is warranted to elucidate the potential advantages of focal radiation techniques for treating PCa. Prospero Registration Number: CRD42014014765.

k-space sampling optimization for ultrashort TE imaging of cortical bone: applications in radiation therapy planning and MR-based PET attenuation correction

PURPOSE

The ultrashort echo-time (UTE) sequence is a promising MR pulse sequence for imaging cortical bone which is otherwise difficult to image using conventional MR sequences and also poses strong attenuation for photons in radiation therapy and PET imaging. The authors report here a systematic characterization of cortical bone signal decay and a scanning time optimization strategy for the UTE sequence through k-space undersampling, which can result in up to a 75% reduction in acquisition time. Using the undersampled UTE imaging sequence, the authors also attempted to quantitatively investigate the MR properties of cortical bone in healthy volunteers, thus demonstrating the feasibility of using such a technique for generating bone-enhanced images which can be used for radiation therapy planning and attenuation correction with PET/MR.

METHODS

An angularly undersampled, radially encoded UTE sequence was used for scanning the brains of healthy volunteers. Quantitative MR characterization of tissue properties, including water fraction and R2(∗) = 1/T2(∗), was performed by analyzing the UTE images acquired at multiple echo times. The impact of different sampling rates was evaluated through systematic comparison of the MR image quality, bone-enhanced image quality, image noise, water fraction, and R2(∗) of cortical bone.

RESULTS

A reduced angular sampling rate of the UTE trajectory achieves acquisition durations in proportion to the sampling rate and in as short as 25% of the time required for full sampling using a standard Cartesian acquisition, while preserving unique MR contrast within the skull at the cost of a minimal increase in noise level. The R2(∗) of human skull was measured as 0.2-0.3 ms(-1) depending on the specific region, which is more than ten times greater than the R2(∗) of soft tissue. The water fraction in human skull was measured to be 60%-80%, which is significantly less than the >90% water fraction in brain. High-quality, bone-enhanced images can be generated using a reduced sampled UTE sequence with no visible compromise in image quality and they preserved bone-to-air contrast with as low as a 25% sampling rate.

CONCLUSIONS

This UTE strategy with angular undersampling preserves the image quality and contrast of cortical bone, while reducing the total scanning time by as much as 75%. The quantitative results of R2(∗) and the water fraction of skull based on Dixon analysis of UTE images acquired at multiple echo times provide guidance for the clinical adoption and further parameter optimization of the UTE sequence when used for radiation therapy and MR-based PET attenuation correction.

A Domain Constrained Deformable (DoCD) Model for Co-registration of Pre- and Post-Radiated Prostate MRI

External beam radiation treatment (EBRT) is a popular method for treating prostate cancer (CaP) involving destroying tumor cells with ionizing radiation. Following EBRT, biochemical failure has been linked with disease recurrence. However, there is a need for methods for evaluating early treatment related changes to allow for an early intervention in case of incomplete disease response. One method for looking at treatment evaluation is to detect changes in MRI markers on a voxel-by-voxel basis following treatment. Changes in MRI markers may be correlated with disease recurrence and complete or partial response. In order to facilitate voxel-by-voxel imaging related treatment changes, and also to evaluate morphologic changes in the gland post treatment, the pre- and post-radiated MRI must first be brought into spatial alignment via image registration. However, EBRT induces changes in the prostate volume and distortion to the internal anatomy of the prostate following radiation treatment. The internal substructures of the prostate, the central gland (CG) and peripheral zone (PZ), may respond to radiation differently, and their resulting shapes may change drastically. Biomechanical models of the prostate that have been previously proposed tend to focus on how external forces affect the surface of the prostate (not the internals), and assume that the prostate is a volume-preserving entity. In this work we present DoCD, a biomechanical model for automatically registering pre-, post-EBRT MRI with the aim of expressly modeling the (1) changes in volume, and (2) changes to the CG and PZ. DoCD was applied to a cohort of 30 patients and achieved a root mean square error of 2.994 mm, which was statistically significantly better a traditional biomechanical model which did not consider changes to the internal anatomy of the prostate (mean of 5.071 mm).

Preclinical evaluation of radiosensitizing activity of Pluronic block copolymers

PURPOSE

Pluronic block copolymers are non-ionic surfactants with demonstrated sensitizing activity in chemotherapy and hyperthermia in various tumor cell lines. In the current study we investigated the potential activity of Pluronic as a radiosensitizing agent.

MATERIALS AND METHODS

As a possible mechanism, the effect of Pluronic on Hsp70 and Hsp90 was examined. Gli36 human glioma cells were treated with radiation alone as well as with a combination treatment of Pluronic and radiation.

RESULTS

Clonogenic cell survival assays show that Pluronic has an elevated effect on radiosensitization (50% high, p < 0.01), even with radiation doses as low as 2 Gy. The Hsp90 level was reduced 24 h after the combined treatment in both in vitro and in vivo. Similarly, Hsp70 levels were also decreased 24 h post treatment. When Gli36 cells were exposed to Pluronic before and during irradiation, DNA DSB: double-strand breaks repair was reduced, and elevated apoptosis was also seen in tumor xenografts.

CONCLUSION

Data suggest the potential use of L10 as a radiosensitizer. While the mechanism of sensitization requires additional investigation, the presented results indicate that the effect may be due, in part, to a decrease in Hsp90 and 70 levels and increased DNA damage.

Role of Pluronic block copolymers in modulation of heat shock protein 70 expression

PURPOSE

The goal of this study was to evaluate the relationship between previously demonstrated thermosensitising effects of the block copolymer, Pluronic, and heat shock protein 70 (Hsp70) expression in an experimental colorectal cancer model in vitro and in vivo.

MATERIALS AND METHODS

Rat colorectal carcinoma cells were treated with low-grade hyperthermia (43°C) alone or in combination with Pluronics L10 (3 mg/mL), L61 (0.3 mg/mL), or L64 (0.5 mg/mL) for 20 min. Adinosine triphosphate (ATP) levels and cell viability were determined using standard assays. Hsp70 expression was quantified by western blot for cells treated with L10, L61, and L64 at doses specified above and Pluronic P85 (10 mg/mL) alone and in combination with heat. BDIX rats with flank tumours were used to study the effect of L61 and hyperthermia on Hsp70 expression in vivo.

RESULTS

In vitro, treatment with L10, L61, and L64 plus low-grade hyperthermia lead to depletion of ATP levels to between 8 and 66% of untreated control after 24 h. Maximum expression of Hsp70 was observed at 9 h following hyperthermia alone. The combination of low-grade hyperthermia and Pluronic treatment reduced Hsp70 expression for up to 6 hours, and L10 appeared to completely inhibit the Hsp70 expression. In vivo, Hsp70 expression was increased 5 h after hyperthermia in BDIX rat tumour models and no Hsp70 expression was observed in L61 pre-treated and control groups.

CONCLUSION

Pluronic effectively improves hyperthermic and low-grade hyperthermic treatment in part due to reduction of Hsp70 expression.

Radiofrequency ablation induces antigen-presenting cell infiltration and amplification of weak tumor-induced immunity

PURPOSE

To evaluate the influence of subtotal radiofrequency (RF) ablation on a tumor-specific immune response in a murine tumor model and to explore the role of intratumoral dendritic cells (ITDCs) in mediating this effect.

MATERIALS AND METHODS

Animal work was performed according to an approved protocol and in compliance with the National Cancer Institute Animal Care and Use Committee guidelines and regulations. A murine urothelial carcinoma (MB49) model expressing the male minor histocompatibility (HY) antigen was inoculated subcutaneously in female mice. Fourteen days later, splenic T cells were analyzed with enzyme-linked immunosorbent spot for HY immune response (n = 57). In subsequent experiments, mice were randomized into control (n = 7), RF ablation, ITDC (n = 9), and RF ablation + ITDC (n = 9) groups and monitored for tumor growth. Eleven days after treatment, tumors were harvested for histologic and immunohistochemical analysis. Animals demonstrating complete tumor regression were rechallenged in the contralateral flank.

RESULTS

Animals treated with subtotal RF ablation showed significant increases in tumor-specific class I and II responses to HY antigens and tumor regression. RF ablation, ITDC, and combined groups demonstrated similar levels of antigen-presenting cell infiltration; all groups demonstrated greater levels of infiltration compared with untreated controls. ITDC injection also resulted in tumor regression. However, combination therapy did not enhance tumor regression when compared with either treatment alone. Rechallenged mice in RF ablation, ITDC, and combination groups demonstrated significant tumor growth inhibition compared with controls.

CONCLUSION

Subtotal RF ablation treatment results in enhanced systemic antitumor T-cell immune responses and tumor regression that is associated with increased dendritic cell infiltration. ITDC injection mimics the RF ablation effect but does not increase immune responses when injected immediately after RF ablation.

Pulsed high-intensity focused ultrasound enhances apoptosis and growth inhibition of squamous cell carcinoma xenografts with proteasome inhibitor bortezomib

PURPOSE

To investigate whether combining pulsed high-intensity focused ultrasound (HIFU) with the chemotherapeutic drug bortezomib could improve antitumor activity against murine squamous cell carcinoma (SCC) tumors.

MATERIALS AND METHODS

All experiments were conducted with animal care and use committee approval. Murine SCC cells were implanted subcutaneously in C3H mice. When tumors reached 100 mm(3), mice were randomized to one of three groups for twice weekly intraperitoneal injections of 1.5 mg of bortezomib per kilogram of body weight, a proteasome inhibitor (n = 10); 1.0 mg/kg bortezomib (n = 11); or a control vehicle (n = 12). Within each group, half of the mice received pulsed HIFU exposure to their tumors immediately prior to each injection. The time for tumors to reach 650 mm(3) was compared among groups. Additional tumors were stained with terminal deoxynucledotidyl transferase-mediated dUTP nick end labeling and CD31 to assess apoptotic index and blood vessel density, respectively.

RESULTS

Tumors in the control group, pulsed HIFU and control group, and 1.0 mg/kg of bortezomib alone group reached the size end point in 5.2 days +/- 0.8 (standard deviation), 5.3 days +/- 0.8, and 5.6 days +/- 1.1, respectively. However, pulsed HIFU and 1.0 mg/kg bortezomib increased the time to end point to 9.8 days +/- 2.9 (P < .02), not significantly different from the 8.8 days +/- 2.1 in tumors treated with 1.5 mg/kg bortezomib alone (P > .05). Combination therapy was also associated with a significantly higher apoptotic index (P < .05).

CONCLUSION

Treatment of tumors with pulsed HIFU lowered the threshold level for efficacy of bortezomib, resulting in significant tumor cytotoxicity and growth inhibition at lower dose levels.

Pulsed-high intensity focused ultrasound and low temperature-sensitive liposomes for enhanced targeted drug delivery and antitumor effect

PURPOSE

To determine if pulsed-high intensity focused ultrasound (HIFU) could effectively serve as a source of hyperthermia with thermosensitive liposomes to enhance delivery and efficacy of doxorubicin in tumors.

EXPERIMENTAL DESIGN

Comparisons in vitro and in vivo were carried out between non-thermosensitive liposomes (NTSL) and low temperature-sensitive liposomes (LTSL). Liposomes were incubated in vitro over a range of temperatures and durations, and the amount of doxorubicin released was measured. For in vivo experiments, liposomes and free doxorubicin were injected i.v. in mice followed by pulsed-HIFU exposures in s.c. murine adenocarcinoma tumors at 0 and 24 h after administration. Combinations of the exposures and drug formulations were evaluated for doxorubicin concentration and growth inhibition in the tumors.

RESULTS

In vitro incubations simulating the pulsed-HIFU thermal dose (42 degrees C for 2 min) triggered release of 50% of doxorubicin from the LTSLs; however, no detectable release from the NTSLs was observed. Similarly, in vivo experiments showed that pulsed-HIFU exposures combined with the LTSLs resulted in more rapid delivery of doxorubicin as well as significantly higher i.t. concentration when compared with LTSLs alone or NTSLs, with or without exposures. Combining the exposures with the LTSLs also significantly reduced tumor growth compared with all other groups.

CONCLUSIONS

Combining low-temperature heat-sensitive liposomes with noninvasive and nondestructive pulsed-HIFU exposures enhanced the delivery of doxorubicin and, consequently, its antitumor effects. This combination therapy could potentially produce viable clinical strategies for improved targeting and delivery of drugs for treatment of cancer and other diseases.

Initial experience in small animal tumor imaging with a clinical positron emission tomography/computed tomography scanner using 2-[F-18]fluoro-2-deoxy-D-glucose

The feasibility of small animal imaging using a clinical positron emission tomography/computed tomography (PET/CT) scanner with [F-18]-fluoro-2-deoxy-D-glucose (FDG) was evaluated. As tumor-bearing small animal models, rabbits with VX-2 liver tumors, rats with mammary tumors on the back, and mice with LS174T human colon tumor xenografts were prepared. Two-dimensional PET, CT, and fused PET/CT images were obtained and reconstructed with a combined PET/CT system using a conventional protocol for humans and dedicated high-resolution mode protocols specialized for each species. Estimated radioactivity concentrations in tumors and normal organs determined noninvasively on FDG-PET/CT were compared with the actual tissue radioactivity levels determined from gamma-counting after vivisection in rats. In addition, recovery-corrected radioactivity concentrations were calculated and evaluated using the tumor/normal organ sizes measured on CT. Tumors in rabbits and rats were clearly visualized by FDG-PET/CT in the dedicated protocols, and images were considered suitable for research purposes. With the aid of thin-slice CT-mapping images, FDG uptake was correctly localized in the viable tumor regions. In mice, increased FDG uptake in tumors with varying activity levels was observed, but detailed anatomical information was not optimally provided from the images, even using specialized protocols. The estimated radioactivity concentrations of tumors and normal organs were close to the actual radioactivity concentrations obtained by gamma-counting (r = 0.97, P < 0.001, the estimated/actual slope: 1) when recovery correction was applied using the sample sizes measured on CT. FDG-PET/CT imaging with a modern clinical scanner was demonstrated to be feasible, of excellent quality, and quite quantitatively accurate for research in rabbits or rats with tumors of appropriate size (>2 cm without recovery correction and >1 cm with recovery correction). Evaluation of FDG uptake within a tumor was possible with the aid of CT images. Dedicated small animal PET/CT scanner would be better suited for evaluating tumor-bearing mice and likely could enhance imaging smaller tumors in rabbits or rats. Although it has limitations, small animal imaging with a clinical PET/CT scanner may be quite adequate for sequential noninvasive imaging in oncology research because the CT is of high resolution, allowing for localization of PET findings and for more precise noninvasive estimation of radioactivity concentration through partial volume corrections.

Prompted voiding treatment of urinary incontinence in nursing home patients. A behavior management approach for nursing home staff

This study evaluated a treatment procedure in which 126 incontinent nursing home patients were checked on an hourly basis, asked if they needed toileting assistance (prompted), and socially reinforced for appropriate toileting. Urodynamic analysis (including cystometrogram), provocative stress test, and behavioral assessment revealed that the nursing home patients were severely debilitated, with 65% demonstrating bladder abnormalities, 87% incapable of independent toileting, and 25% failing to score on the Mini-Mental Status Exam (average score, 8.0). The treatment procedures were evaluated with a multiple baseline design in which subjects were randomly divided into immediate or delayed treatment groups after a baseline observation period. During treatment, the frequency of incontinence per 12 hours changed from a baseline average of 3.85 to a treatment average of 1.91. Three behavioral measures that can be easily collected by nursing staff significantly predicted continence levels during treatment (multiple R, 0.79) and change in incontinence during treatment (multiple R, 0.64). These prognostic criteria offer nursing staff a cost-effective method for selecting the most responsive patients for prompted-voiding treatment.

Behavioral management in the inpatient geriatric population

Urinary incontinence is a reversible problem in many nursing home patients. The types of patients that respond to nursing management procedures have been identified in this article. Specific diagnostic and rehabilitative assessments, as well as treatment procedures, have been described in a fashion that makes them usable by most nursing professionals in long-term care facilities. Two key issues remain to be addressed. The foremost issue is that, once patients are taught to request toileting assistance, the challenge remains to motivate staff to render that assistance over long periods of time. Second, a number of patients with urologic conditions (most notably, high residual urine volumes and low bladder capacities) do not respond well to nursing management. The type of medical or nursing treatment best suited for these patients has not yet been resolved. Nevertheless, this article has detailed techniques that positively affect incontinence in nursing home patients. Nursing implementation of prompted voiding can dramatically improve continence within the geriatric inpatient population.

Reduction of urinary incontinence in nursing homes: does it reduce or increase costs?

Labor and supply costs associated with the care of urinary incontinent patients in three nursing homes were measured. First, normal nursing home changing patterns and their associated costs were measured. Second, the costs were documented when patients were checked by research staff and changed on an hourly basis as needed. Nursing home staff changed patients significantly less frequently than patient voiding as detected by the hourly checking system. Thus, cost of incontinence during the hourly checking condition ($3.35) per 12-hour patient-day was significantly higher than the cost normally incurred in nursing homes ($1.52) per 12-hour patient-day. The cost of an incontinence rehabilitation program, which significantly reduced incontinence episodes, was contrasted to the cost of incontinence as measured under both of the previous conditions. The rehabilitation program produced significant labor and supply savings only when compared with the hourly checking and changing system. Maintaining patients in a more continent condition costs significantly more than the direct incontinence cost normally incurred by the nursing home. Quality of life and other second-order benefits must be considered if continence rehabilitation is to be judged cost-effective.

Behavioral covariation in the treatment of chronic pain

The successful use of operant procedures to alter behaviors associated with various medical conditions suggests that such behaviors may be learned and that the principles of learning may be applied not only to treatment but also to the study of the pathogenesis of illness behavior. The present study, conducted within an ongoing neuromuscular research project, assessed the covariation of behaviors associated with chronic pain within and across behavioral and drug approaches to treatment. Problems of screaming and five other behaviors (including self-reports of pain) were measured across conditions of varying behavioral contingencies (noncontingent reinforcement vs the removal of reinforcement contingent upon screaming) and varying administration (time since medication and dosage) of Parsidol during attempts to treat the muscle pain of a 24-year-old male with a severe, chronic neuromuscular disorder diagnosed as dystonia musculorum deformans (DMD). Results indicated that: (a) pain behaviors covaried during behavioral and drug conditions even though the behavioral intervention only targeted screaming; (b) effects were greater on nontargeted behaviors during periods that followed rather than preceded drug administration; (c) in contrast to behavioral observation data, physiological measures of neuromuscular activity (EMG) did not differ across conditions. These results suggest that functional response-response relationships exist in patients as the result of their illness experience.

Management of geriatric incontinence in nursing homes

A behavioral management system designed to reduce urinary incontinence was evaluated in two nursing homes with a pretest-posttest control group design with repeated measures. The primary components of the system were prompting and contingent social approval/disapproval which required approximately 2.5 minutes per patient per hour to administer. The frequency of correct toileting for experimental subjects increased by approximately 45%. The experimental groups were significantly different from the control groups on both incontinence and correct toileting measures. The results are discussed in view of the management issues inherent in nursing home settings.