Development and Implementation of an Online Adaptive Stereotactic Body Radiation Therapy Workflow for Treatment of Intracardiac Metastasis

Cardiac metastases pose clinical challenges for radiation oncologists given the need to balance the benefit of local therapy against the risks of cardiac toxicity in the setting of cardiac motion, respiratory motion, and nearby organs at risk. Stereotactic magnetic resonance-guided adaptive radiation therapy has recently become more commonly used, conferring benefits in tumor visualization for setup, real-time motion management monitoring, and enabling plan adaptation for daily changes in tumor and/or normal tissues. Given these benefits, we developed and implemented a workflow for local treatment of metastatic disease within the heart using stereotactic magnetic resonance-guided adaptive radiation therapy.

Use of a healthy volunteer imaging program to optimize clinical implementation of stereotactic MR-guided adaptive radiotherapy

PURPOSE

MR-linacs (MRLs) have enabled the use of stereotactic magnetic resonance (MR) guided online adaptive radiotherapy (SMART) across many cancers. As data emerges to support SMART, uncertainty remains regarding optimal technical parameters, such as optimal patient positioning, immobilization, image quality, and contouring protocols. Prior to clinical implementation of SMART, we conducted a prospective study in healthy volunteers (HVs) to determine optimal technical parameters and to develop and practice a multidisciplinary SMART workflow.

METHODS

HVs 18 years or older were eligible to participate in this IRB-approved study. Using a 0.35 T MRL, simulated adaptive treatments were performed by a multi-disciplinary treatment team in HVs. For each scan, image quality parameters were assessed on a 5-point scale (5 = extremely high, 1 = extremely poor). Adaptive recontouring times were compared between HVs and subsequent clinical cases with a t-test.

RESULTS

18 simulated treatments were performed in HVs on MRL. Mean parameters for visibility of target, visibility of nearby organs, and overall image quality were 4.58, 4.62, and 4.62, respectively (range of 4-5 for all measures). In HVs, mean ART was 15.7 min (range 4-35), comparable to mean of 16.1 (range 7-33) in the clinical cases (p = 0.8963). Using HV cases, optimal simulation and contouring guidelines were developed across a range of disease sites and have since been implemented clinically.

CONCLUSIONS

Prior to clinical implementation of SMART, scans of HVs on an MRL resulted in acceptable image quality and target visibility across a range of organs with similar ARTs to clinical SMART. We continue to utilize HV scans prior to clinical implementation of SMART in new disease sites and to further optimize target tracking and immobilization. Further study is needed to determine the optimal duration of HV scanning prior to clinical implementation.

Feasibility of deploying a U.S. simulation-based gynecological brachytherapy educational workshop to an international setting

PURPOSE

A decline in brachytherapy (BT) use for cervical cancer has negatively affected cure rates in the United States and abroad. To improve trainee exposure to BT, a simulation-based educational curriculum incorporating a pelvic mannequin was developed and implemented at several U.S. residency programs. We sought to describe an initial experience with deployment of this curriculum to an international setting.

METHODS AND MATERIALS

The setting was in Israel, a middle eastern country with cervical cancer incidence of 5-8 cases per 100,000 women. Israel was selected for this pilot because of its desire to increase exposure to trainees, lack of mandatory BT case requirements, and few residencies nationally. In determining the feasibility of deployment to this setting, a partnership was formed between a U.S. and Israeli brachytherapist to understand cultural context and institutional and logistical needs. Feasibility was defined as successful completion of the workshop. Trainee comfort and knowledge with BT was assessed with preworkshop and postworkshop surveys, with changes compared.

RESULTS

The curriculum was incorporated into a 1-day course on gynecologic malignancies, with adaptation to local setting and routine. Among 15 attendees, eight were residents, from four programs. All completed the workshop. All domains assessed by the surveys improved and all respondents found the program to be helpful.

CONCLUSIONS

International deployment of the simulation-based educational BT curriculum was feasible and well-received. Further collaboration is needed to deploy and adapt the curriculum to countries of high cervical cancer incidence that could benefit from increased education.

A new development in ultrasound-compatible gynecologic brachytherapy simulators

PURPOSE

Gynecologic brachytherapy is an essential component in the curative treatment of cervical cancer. With the decline in brachytherapy utilization, gynecologic brachytherapy simulators are being used to provide a mechanism to enhance proficiency-based resident training. However, most models that have been used lack procedural fidelity as they are either repurposed from OB/GYN basic models or from physics phantoms. Therefore, we set out to develop a high-fidelity, ultrasound- and CT-compatible gynecologic brachytherapy training simulator.

METHODS AND MATERIALS

Based on prior experience with gynecologic training simulators on the market, we developed a wish list for an ultrasound-compatible brachytherapy training model. A custom simulator was developed based on an existing pelvic ultrasound trainer. Features included a cervical os and endometrial canal as well as a palpable and hypoechoic cervical tumor.

RESULTS

The model took about 3 months from the initial meeting with the developer to completion. The properties of the material were equivalent to water for ultrasound, CT, and also MRI and the model did not show signs of degradation after multiple tandem insertions.

CONCLUSIONS

A high-fidelity ultrasound-compatible simulator was effectively developed and utilized to improve resident training to perform brachytherapy implants with a derivative benefit in the long term of improving survival for women with advanced gynecologic malignancies through having access to more proficient brachytherapists. Future directions include enhancing the model to allow for repetitive needle insertion and suturing for interstitial training as well as creating variations in anatomy (e.g., retroverted uterus, bulky tumors, etc.) for more advanced technical training.

Simulation-based graduate medical education in MR-guided brachytherapy for cervical cancer

PURPOSE

Brachytherapy is critical for the curative treatment of locally advanced cervical cancer. Although brachytherapy use is declining in the United States (U.S.), novel interstitial or intracavitary applicators and advances in image guidance for applicator placement and treatment planning have allowed for tumor dose escalation while reducing normal tissue toxicity. Recent survey data have suggested insufficient brachytherapy training for radiation oncology trainees in the United States. This study aimed to address these gaps by developing and piloting a simulation-based education (SBE) workshop for MR-guided cervical cancer brachytherapy.

METHODS AND MATERIALS

An SBE workshop was developed for graduate medical education (GME) trainees focusing on MR-guided brachytherapy for cervical cancer. Four hands-on stations, simulating aspects of the procedure, were led by a team of gynecological brachytherapy experts. The learners were radiation oncology residents and fellows in a U.S. GME training program. The primary outcome was feasibility, assessed by completion of the workshop within the time constraints of the curriculum. Learners completed preworkshop and postworkshop surveys to provide information on efficacy.

RESULTS

The workshop was successfully completed in a 1-h block of GME didactic time. Ten trainees completed all four stations, and all completed preworkshop and postworkshop surveys, which showed improvements in knowledge and technical proficiency. Feedback was positive, and trainees requested additional learning opportunities.

CONCLUSIONS

This study showed that GME-focused SBE in MR-guided cervical cancer brachytherapy was feasible. SBE provided a nonclinical environment in which to practice aspects of MR-guided brachytherapy. Ongoing work includes collaboration with other U.S. institutions. Future studies should focus on international adaptation.

Severe metabolic acidosis due to acetazolamide intoxication in a dog

CASE REPORT

This case report describes the clinical signs and case management of a 1-year-old neutered male Siberian Husky that accidentally ingested 635 mg/kg of oral acetazolamide (a carbonic anhydrase inhibitor). The dog presented with severe tachypnoea due to the development of hyperchloraemic metabolic acidosis and associated hypokalaemia that persisted for 7 days. Clinical and biochemical changes resolved with intravenous and subsequent oral supplementation of sodium bicarbonate and potassium. Complete recovery occurred within 9 days of presentation.

CONCLUSION

To the authors' knowledge, this is the first case that reports overdosage of an oral carbonic anhydrase inhibitor in a dog and subsequent recovery with adequate supplementation and supportive care.

Clinical Characteristics Associated With Stuttering Persistence: A Meta-Analysis

Purpose The purpose of this meta-analytic study was to identify clinical characteristics, defined as child factors that can be assessed by a speech-language pathologist as part of a routine speech-language evaluation that may differentiate children who persist in stuttering from children who eventually recover from stuttering. Clinical characteristics explored included sex, age at onset, family history of stuttering, stuttering frequency and severity, speech-language skills, and temperament. Method Studies were identified through electronic databases, journals, and reference lists of relevant reports (e.g., research articles). Eligible studies followed young children who stutter (i.e., under 6 years old) for at least 24 months, assessed a potential clinical marker at study entry, and determined talker group classification (i.e., persistent or recovered) at study completion. Sex and family history differences were estimated using risk ratios; all other differences were estimated using Hedges's g. Heterogeneity and methodological differences among studies were evaluated. Results Eleven studies (41 reports) met eligibility criteria. Persistent children were older at stuttering onset and exhibited higher frequencies of stuttering-like disfluencies, lower speech sound accuracy, and lower expressive and receptive language skills than recovered children. Males and children with a family history of stuttering were also more likely to persist. Conclusions Clinical characteristics were identified that are associated with increased risk for stuttering persistence. Future studies have the potential to translate these clinical characteristics into prognostic markers for stuttering persistence risk.

A review of the role of MRI in diagnosis and treatment of early stage lung cancer

Despite magnetic resonance imaging (MRI) being a mainstay in the oncologic care for many disease sites, it has not routinely been used in early lung cancer diagnosis, staging, and treatment. While MRI provides improved soft tissue contrast compared to computed tomography (CT), an advantage in multiple organs, the physical properties of the lungs and mediastinum create unique challenges for lung MRI. Although multi-detector CT remains the gold standard for lung imaging, advances in MRI technology have led to its increased clinical relevance in evaluating early stage lung cancer. Even though positron emission tomography is used more frequently in this context, functional MR imaging, including diffusion-weighted MRI and dynamic contrast-enhanced MRI, are emerging as useful modalities for both diagnosis and evaluation of treatment response for lung cancer. In parallel with these advances, the development of combined MRI and linear accelerator devices (MR-linacs), has spurred the integration of MRI into radiation treatment delivery in the form of MR-guided radiotherapy (MRgRT). Despite challenges for MRgRT in early stage lung cancer radiotherapy, early data utilizing MR-linacs shows potential for the treatment of early lung cancer. In both diagnosis and treatment, MRI is a promising modality for imaging early lung cancer.

Risk of Nephrogenic Systemic Fibrosis in Patients With Stage 4 or 5 Chronic Kidney Disease Receiving a Group II Gadolinium-Based Contrast Agent: A Systematic Review and Meta-analysis

IMPORTANCE

Risk of nephrogenic systemic fibrosis (NSF) to individual patients with stage 4 or 5 chronic kidney disease (CKD; defined as estimated glomerular filtration rate of <30 mL/min/1.73 m2) who receive a group II gadolinium-based contrast agent (GBCA) is not well understood or summarized in the literature.

OBJECTIVE

To assess the pooled risk of NSF in patients with stage 4 or 5 CKD receiving a group II GBCA.

DATA SOURCES

A health sciences informationist searched the Ovid (MEDLINE and MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citation, and Daily and Versions), Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Open Grey databases from inception to January 29, 2019, yielding 2700 citations.

STUDY SELECTION

Citations were screened for inclusion in a multistep process. Agreement for final cohort inclusion was determined by 2 blinded screeners using Cohen κ. Inclusion criteria consisted of stage 4 or 5 CKD with or without dialysis, administration of an unconfounded American College of Radiology classification group II GBCA (gadobenate dimeglumine, gadobutrol, gadoterate meglumine, or gadoteridol), and incident NSF as an outcome. Conference abstracts, retracted manuscripts, narrative reviews, editorials, case reports, and manuscripts not reporting total group II GBCA administrations were excluded.

DATA EXTRACTION AND SYNTHESIS

Data extraction was performed for all studies by a single investigator, including publication details, study design and time frame, patient characteristics, group II GBCA(s) administered, total exposures for patients with stage 4 or stage 5 CKD, total cases of unconfounded NSF, reason for GBCA administration, follow-up duration, loss to follow-up, basis for NSF screening, and diagnosis.

MAIN OUTCOMES AND MEASURES

Pooled incidence of NSF and the associated upper bound of a 2-sided 95% CI (risk estimate) for the pooled data and each of the 4 group II GBCAs.

RESULTS

Sixteen unique studies with 4931 patients were included (κ = 0.68) in this systematic review and meta-analysis. The pooled incidence of NSF was 0 of 4931 (0%; upper bound of 95% CI, 0.07%). The upper bound varied owing to different sample sizes for gadobenate dimeglumine (0 of 3167; upper bound of 95% CI, 0.12%), gadoterate meglumine (0 of 1204; upper bound of 95% CI, 0.31%), gadobutrol (0 of 330; upper bound of 95% CI, 1.11%), and gadoteridol (0 of 230; upper bound of 95% CI, 1.59%).

CONCLUSIONS AND RELEVANCE

This study's findings suggest that the risk of NSF from group II GBCA administration in stage 4 or 5 CKD is likely less than 0.07%. The potential diagnostic harms of withholding group II GBCA for indicated examinations may outweigh the risk of NSF in this population.

TRIAL REGISTRATION

PROSPERO identifier: CRD42019123284.

Low-Dose Adjuvant Cylinder Brachytherapy for Endometrioid Endometrial Cancer

PURPOSE

Our purpose was to evaluate outcomes and sites of failure for women with early stage endometrial adenocarcinoma treated with adjuvant high-dose-rate (HDR) vaginal brachytherapy (VB) with a low dose scheme.

METHODS AND MATERIALS

Retrospective review identified 318 patients with International Federation of Gynecology and Obstetrics (FIGO) stage I-II endometrioid endometrial cancer who received adjuvant HDR VB to a dose of 24 Gray (Gy) in 6 fractions from 2005 to 2017. Patients with <6 months follow-up were excluded. Dose was prescribed to cylinder surface and computerized tomography (CT) imaging was performed before each fraction to assess cylinder placement. Rates of vaginal relapse (VR), pelvic nodal relapse, distant metastasis, recurrence-free survival, and overall survival were calculated by Kaplan-Meier method. Univariate analysis was performed by log rank test or Cox proportional hazards. Pretreatment CT images were analyzed for patients with VR.

RESULTS

Median follow-up was 42 months for 243 patients. The 3-year rates of VR, pelvic nodal relapse, distant metastasis, recurrence-free survival, and overall survival were 1.9%, 1.5%, 4.3%, 94.1%, and 98.9%, respectively. The 3-year VR rates by Gynecologic Oncology (GOG)-99 risk groups were 0%, 1.4%, and 3.2% for low risk, low-intermediate risk, and high-intermediate risk (HIR) disease (P = .5). By Post-operative Radiation Therapy in Endometrial Carcinoma (PORTEC) risk stratification, 3-year VR rate was 1.3% for HIR disease. On review of pretreatment CT images of the 6 patients with VR, 3 patients had relapse at the introitus outside of the treated vaginal length, and 3 had in-field recurrence at the vaginal apex. Higher body mass index (BMI) was associated with VR, with a 14% increase in risk per BMI unit (kg/m², P = .02). There were no reported grade 2 GI or any grade 3 toxicities.

CONCLUSIONS

Adjuvant HDR VB with a low-dose regimen results in excellent clinical outcomes for patients with early stage endometrioid endometrial cancer. Patients with higher BMI may be at increased risk of VR, and additional study is needed to optimize brachytherapy treatment parameters.

Development and Implementation of a Simulation-Based Educational Workshop on Gynecological Brachytherapy: Pilot Study at a National Meeting

PURPOSE

Despite the importance of brachytherapy in the curative treatment of locally advanced cervical cancer, reviews of practice patterns in the United States have identified a decline in brachytherapy use in clinically appropriate patient populations. A survey of radiation oncologists identified lack of time and lack of guidance as barriers. To address these barriers, the purpose of this study was to develop a simulation-based educational (SBE) gynecologic brachytherapy workshop.

METHODS AND MATERIALS

The SBE gynecologic brachytherapy workshop was developed with expertise from 2 institutions, combining procedural simulation with a practical discussion of brachytherapy applicator insertion techniques. The primary outcome was feasibility of workshop deployment, defined as completion of all workshop components in the time allotted. Preworkshop and postworkshop surveys were also administered to assess efficacy, a secondary outcome.

RESULTS

The workshop took place at a national radiation oncology meeting, and all workshop components were completed in the 2 hours allotted. SBE stations focused on (1) fiducial placement, (2-3) applicator selection, (4) suturing, and (5) pelvic examination and applicator placement. Fourteen participants completed surveys. Respondents included residents and attending physicians. More than 50% of respondents were from academic practices and practiced gynecologic brachytherapy weekly or more. Curricular objectives for this workshop were for ≥20% trainees to report increased confidence in practice and ≥20% of trainees to report increased familiarity with applicators. After participation in the workshop, confidence in applicator choice improved in 9 of 13 participants (69%), confidence in complication management improved in 8 of 13 participants (62%), and familiarity with applicators improved in 7 of 13 participants (54%). These differences were statistically significant at α = .05.

CONCLUSIONS

This study demonstrated feasibility in using simulation for gynecologic brachytherapy education at a national meeting. Although most respondents were experienced in brachytherapy, more than half reported increased confidence and familiarity with aspects of the procedure after the workshop. Future work should address interstitial needle placement and improved time management of workshop stations.