Image quality comparisons of coil setups in 3T MRI for brain and head and neck radiotherapy simulations

PURPOSE

MRI is increasingly used for brain and head and neck radiotherapy treatment planning due to its superior soft tissue contrast. Flexible array coils can be arranged to encompass treatment immobilization devices, which do not fit in diagnostic head/neck coils. Selecting a flexible coil arrangement to replace a diagnostic coil should rely on image quality characteristics and patient comfort. We compared image quality obtained with a custom UltraFlexLarge18 (UFL18) coil setup against a commercial FlexLarge4 (FL4) coil arrangement, relative to a diagnostic Head/Neck20 (HN20) coil at 3T.

METHODS

The large American College of Radiology (ACR) MRI phantom was scanned monthly in the UFL18, FL4, and HN20 coil setup over 2 years, using the ACR series and three clinical sequences. High-contrast spatial resolution (HCSR), image intensity uniformity (IIU), percent-signal ghosting (PSG), low-contrast object detectability (LCOD), signal-to-noise ratio (SNR), and geometric accuracy were calculated according to ACR recommendations for each series and coil arrangement. Five healthy volunteers were scanned with the clinical sequences in all three coil setups. SNR, contrast-to-noise ratio (CNR) and artifact size were extracted from regions-of-interest along the head for each sequence and coil setup. For both experiments, ratios of image quality parameters obtained with UFL18 or FL4 over those from HN20 were formed for each coil setup, grouping the ACR and clinical sequences.

RESULTS

Wilcoxon rank-sum tests revealed significantly higher (p < 0.001) LCOD, IIU and SNR, and lower PSG ratios with UFL18 than FL4 on the phantom for the clinical sequences, with opposite PSG and SNR trends for the ACR series. Similar statistical tests on volunteer data corroborated that SNR ratios with UFL18 (0.58 ± 0.19) were significantly higher (p < 0.001) than with FL4 (0.51 ± 0.18) relative to HN20.

CONCLUSIONS

The custom UFL18 coil setup was selected for clinical application in MR simulations due to the superior image quality demonstrated on a phantom and volunteers for clinical sequences and increased volunteer comfort.

Education in gynecological brachytherapy

Brachytherapy is an essential component in the curative treatment of many gynecological malignancies. In the past decade, advances in magnetic resonance imaging and the ability to adapt and customize treatment with hybrid interstitial applicators have led to improved clinical outcomes with decreased toxicity. Unfortunately, there has been a shift in clinical practice away from the use of brachytherapy in the United States. The decline in brachytherapy is multifactorial, but includes both a lack of exposure to clinical cases and an absence of standardized brachytherapy training for residents. In other medical specialties, a clear relationship has been established between clinical case volumes and patient outcomes, especially for procedural-based medicine. In surgical residencies, simulation-based medical education (SBME) is a required component of the program to allow for some autonomy before operating on a patient. Within radiation oncology, there is limited but growing experience with SBME for training residents and faculty in gynecological brachytherapy. This review includes single institutional, multi-institutional and national initiatives using creative strategies to teach the components of gynecological brachytherapy. These efforts have measured success in various forms; the majority serve to improve the confidence of the learners, and many have also demonstrated improved competence from the training as well. The American Brachytherapy Society launched the 300 in 10 initiative in 2020 with a plan of training 30 competent brachytherapists per year over a 10 year period and has made great strides with a formal mentorship program as well as externships available to senior residents interested in starting brachytherapy programs. Moving forward, these curricula could be expanded to provide standardized brachytherapy training for all residents. SBME could also play a role in initial certification and maintenance of certification. Given the burden of disease, it would be valuable to develop similar training for providers in low and middle income countries.

MR-guided prostate SBRT with daily online plan adaptation: Results of a prospective phase I trial and supplemental cohort

Purpose

Stereotactic magnetic resonance (MR)–guided adaptive radiation therapy (SMART) for prostate cancer allows for MR-based contouring, real-time MR motion management, and daily plan adaptation. The clinical and dosimetric benefits associated with prostate SMART remain largely unknown.

Methods and Materials

A phase 1 trial of prostate SMART was conducted with primary endpoints of safety and feasibility. An additional cohort of patients similarly treated with prostate SMART were included in the analysis. SMART was delivered to 36.25 Gy in 5 fractions to the prostate ± seminal vesicles using the MRIdian linear accelerator system (ViewRay, Inc). Rates of urinary and gastrointestinal toxic effects and patient-reported outcome measures were assessed. Dosimetric analyses were conducted to evaluate the specific benefits of daily plan adaptation.

Results

The cohort included 22 patients (n = 10 phase 1, n = 12 supplemental) treated in 110 fractions. Median follow-up was 7.9 months. Acute grade 2 urinary and gastrointestinal toxic effects were observed in 22.7% and 4.5%, respectively, and 4.5% and 0%, respectively, at last follow-up. No grade 3+ events were observed. Expanded Prostate Cancer Index-26 urinary obstructive scores decreased during SMART (mean, 9.3 points; P = .03) and returned to baseline by 3 months. No other significant changes in patient-reported outcome measures were observed. One-hundred percent of fractions required plan adaptation owing to exceeding organ-at-risk metrics (68%) or suboptimal target coverage (33%) resulting from anatomic changes. Minimum acceptable planning target volume, rectal, bladder, and urethra/bladder neck metrics were violated in 24%, 20%, 24%, and 33% of predicted plans, respectively; 0% of reoptimized plans violated metrics. Underlying causes for deficient dosimetry before reoptimization included changes in bladder filling, seminal vesicle position, prostate volume (median 4.7% increase by fraction 3; range, 0%-56%), and hotspots shifting into urethra/bladder neck.

Conclusions

Prostate SMART results in low risk of acute toxic effects with improvements in target and organ-at-risk dosimetry. The clinical benefits resulting from daily plan adaptation, including urethra/bladder neck protection, warrant further investigation.

Geographic differences in therapy for stage I non-small-cell lung cancer in older adults

BACKGROUND

Geographic and socioeconomic factors impact patient treatment choices for certain cancers. Whether they impact treatment in older adults with lung cancer is unknown. We investigated geographic differences in treatment for stage I non-small-cell lung cancer (NSCLC) in older adults in the United States.

METHODS

Using the Surveillance, Epidemiology and End Results Database 18th submission, a cohort of stage I NSCLC patients ≥60-years-old was created. Treatment differences (surgery or radiation alone) by geographic location and socioeconomic factors were analyzed.

RESULTS

Forty-three thousand three hundred and eighty-seven stage I NSCLC patients were analyzed. Demographics and socioeconomic factors varied across all 13 states (p < 0.001). Surgery was the most common treatment in all states (range 58.6% in AK to 86.5% in CT) (all p < 0.001). Our multivariable analysis found older individuals had higher odds of getting radiation as compared to surgery (odds ratio [OR]: 1.22 for 65-69 years-old to OR: 8.95 for 85+ years-old; p < 0.001). Multiple states (LA, HI, IA, MI, WA, NM) were associated with increased odds of radiation use (vs. surgery alone) (all p < 0.05). People with lower education level (OR: 0.98) and median income (OR: 0.99) and non-Black race (OR: 0.52 for "other" to OR: 0.68 for "White" race with respect to Black race) were associated with lower odds of radiation (p < 0.05).

CONCLUSIONS

Our study identified treatment differences for stage I NSCLC patients in the United States related to demographics, socioeconomic factors, and geographic location.

Surgical complications and clinical outcomes after dose-escalated trimodality therapy for non-small cell lung cancer in the era of intensity-modulated radiotherapy

BACKGROUND

Trimodality therapy (TMT) with preoperative chemoradiation followed by surgical resection is used for locally-advanced non-small-cell lung cancer (LA-NSCLC). Traditionally, preoperative radiation doses ≤54 Gy are used due to concerns regarding excess morbidity, but little is known about outcomes and toxicities after TMT with intensity-modulated radiotherapy (IMRT) to higher doses.

METHODS

A retrospective analysis of patients who received planned TMT with IMRT for LA-NSCLC at Brigham and Women's Hospital/Dana-Farber Cancer Institute between 2008 and 2017 was performed. Clinical and treatment characteristics, pathologic response, and surgical toxicity were assessed. Kaplan-Meier method and log-rank test was used for survival outcomes. Cox proportional-hazards regression was used for multivariable analysis.

RESULTS

Forty-six patients received less than definitive doses of <60 Gy and 30 patients received definitive doses ≥60 Gy. Surgical outcomes, pathologic complete response, and postoperative toxicity did not differ significantly between the groups. With median follow-up of 3.6 years (range: 0.4-11.4), three-year locoregional recurrence-free survival (78.0% vs. 68.3%, p = 0.51) and overall survival (OS) (61.0% vs. 69.4%, p = 0.32) was not significantly different between patients receiving <60 Gy and ≥60 Gy, respectively. On multivariable analysis, older age, clinical stage, and length of hospital stay (LOS) >7 days were associated with OS.

CONCLUSIONS

With IMRT, there was no increased rate of surgical complications in patients receiving higher doses of radiation. Survival outcomes or LOS did not differ based on radiation dose, but increased LOS was associated with worse OS. Larger prospective studies are needed to further examine outcomes after IMRT in patients with LA-NSCLC receiving TMT.

Rates of invasive disease and outcomes in NSCLC patients with biopsy suggestive of carcinoma in situ

INTRODUCTION

Carcinoma in situ is a rare non-invasive histology of non-small cell lung cancer (NSCLC) with excellent survival outcomes with resection. However, management of lung biopsy suggestive of in situ disease remains unclear. To inform decision-making in this scenario, we determined the rate of invasive disease presence upon resection of lesions with an initial biopsy suggestive of purely in situ disease.

METHODS

The study included 960 patients diagnosed with NSCLC from 2003 to 2017 in the National Cancer Database whose workup included a lung biopsy suggestive of in situ disease. Among the cohort who proceeded to resection, we identified the rate of invasive disease discovered on surgical pathology along with significant demographic and clinical contributors to invasion risk. Survival outcomes were measured for the observed cohort that did not receive local therapy after biopsy.

RESULTS

Invasive disease was identified at resection in 49.3 % of patients. Lesion size was associated with risk of invasive disease: 35.7 % for ≤1 cm, 45.2 % for 1-2 cm, 55.7 % for 2-3 cm, and 87.5 % for 3-5 cm (p < 0.001). Of patients with squamous histology, 61.5 % had invasive disease versus 46.5 % with adenocarcinoma histology (p = 0.026). On multivariable logistic regression, invasive disease remained associated with tumor size (OR 1.9 per cm, 95 % CI 1.5-2.4, p < 0.001), and squamous histology (OR 1.8, 95 % CI 1.1-3.2, p = 0.028). Overall survival at 3 years was 51.5 % in the observed cohort.

CONCLUSION

Nearly half of patients with biopsy suggestive of in situ disease had invasive disease at resection. Tumor size and histology are strong predictors of invasive disease and may be used for risk stratification. However, the findings support the practice of definitive therapy whenever feasible.

Definitive radiotherapy for vaginal recurrence of early-stage endometrial cancer: survival outcomes and effect of mismatch repair status

OBJECTIVE

To evaluate clinical outcomes, prognostic factors, and toxicity in patients with vaginal recurrence of early-stage endometrial cancer treated with definitive radiotherapy.

METHODS

Retrospective review identified 62 patients with stage I-II endometrial cancer and vaginal recurrence treated with external beam radiotherapy and image-guided brachytherapy with definitive intent from November 2004 to July 2017. All patients had prior hysterectomy without adjuvant radiotherapy and >3 months follow-up. Mismatch repair (MMR) status was determined by immunohistochemical staining of the four mismatch repair proteins (MLH1, MSH2, PMS2, and MSH6) when available in the pathology record. Rates of vaginal control, recurrence-free survival, and overall survival were calculated by Kaplan-Meier. Univariate and multivariate analyses were performed by Cox proportional hazards.

RESULTS

Most patients had endometrioid histology (55, 89%), grade 1 or 2 tumor (53, 85%), and vaginal-only recurrence (55, 89%). With a median follow-up of 39 months (range, 3-167), 3- and 5-year rates of vaginal control, recurrence-free survival, and overall survival were 86% and 82%, 69% and 55%, and 80% and 61%, respectively. On multivariate analysis, non-endometrioid histology (HR 12.5, P<0.01) was associated with relapse when adjusted for chemotherapy use. Patients with non-endometrioid histology also had a 4.5-fold higher risk of death when adjusted for age (P=0.02). Twenty patients had known MMR status, all with grade 1-2 endometrioid tumors and 10 (50%) with MMR deficiency. The 3-year recurrence-free survival was 100% for MMR-proficient tumors and 52% for MMR-deficient (P=0.03). Late grade 2 and 3 gastrointestinal, genitourinary and vaginal toxicity was reported in 27% and 3%, 15% and 2%, and 16% and 2% of patients, respectively.

CONCLUSION

Definitive radiotherapy with image-guided brachytherapy resulted in 5-year local control rates exceeding 80% and late severe toxicity rates were under 3%. Distant recurrence was common and highest for those with grade 3 or non-endometrioid tumors and MMR deficient grade 1-2 disease.