Abdominal MR Multitasking for radiotherapy treatment planning: A motion-resolved and multicontrast 3D imaging approach.

PURPOSE: Radiotherapy treatment planning (RTP) using MR has been used increasingly for the abdominal site. Multiple contrast weightings and motion-resolved imaging are desired for accurate delineation of the target and various organs-at-risk and patient-tailored planning. Current MR protocols achieve these through multiple scans with distinct contrast and variable respiratory motion management strategies and acquisition parameters, leading to a complex and inaccurate planning process. This study presents a standalone MR Multitasking (MT)-based technique to produce volumetric, motion-resolved, multicontrast images for abdominal radiotherapy treatment planning. METHODS: The MT technique resolves motion and provides a wide range of contrast weightings by repeating a magnetization-prepared (saturation recovery and T2 preparations) spoiled gradient-echo readout series and adopting the MT image reconstruction framework. The performance of the technique was assessed through digital phantom simulations and in vivo studies of both healthy volunteers and patients with liver tumors. RESULTS: In the digital phantom study, the MT technique presented structural details and motion in excellent agreement with the digital ground truth. The in vivo studies showed that the motion range was highly correlated (R2 = 0.82) between MT and 2D cine imaging. MT allowed for a flexible contrast-weighting selection for better visualization. Initial clinical testing with interobserver analysis demonstrated acceptable target delineation quality (Dice coefficient = 0.85 ± 0.05, Hausdorff distance = 3.3 ± 0.72 mm). CONCLUSION: The developed MT-based, abdomen-dedicated technique is capable of providing motion-resolved, multicontrast volumetric images in a single scan, which may facilitate abdominal radiotherapy treatment planning.

Validation of a Resectability Scoring System for Prediction of Pancreatic Adenocarcinoma Surgical Outcomes.

BACKGROUND: The most used pancreatic cancer (PC) resectability criteria are descriptive in nature or based solely on dichotomous degree of involvement (< 180° or > 180°) of vessels, which allows for a high degree of subjectivity and inconsistency. METHODS: Radiographic measurements of the circumferential degree and length of tumor contact with major peripancreatic vessels were retrospectively obtained from pre-treatment multi-detector computed tomography (MDCT) images from PC patients treated between 2001 and 2015 at two large academic institutions. Arterial and venous scores were calculated for each patient, then tested for a correlation with tumor resection and R0 resection. RESULTS: The analysis included 466 patients. Arterial and venous scores were highly predictive of resection and R0 resection in both the training (n = 294) and validation (n = 172) cohorts. A recursive partitioning tree based on arterial and venous score cutoffs developed with the training cohort was able to stratify patients of the validation cohort into discrete groups with distinct resectability probabilities. A refined recursive partitioning tree composed of three resectability groups was generated, with probabilities of resection and R0 resection of respectively 94 and 73% for group A, 61 and 35% for group B, and 4 and 2% for group C. This resectability scoring system (RSS) was highly prognostic, predicting median overall survival times of 27, 18.9, and 13.5 months respectively for patients in RSS groups A, B, and C (p < 0.001). CONCLUSIONS: The proposed RSS was highly predictive of resection, R0 resection, and prognosis for patients with PC when tested against an external dataset.

Factors Impacting Differential Outcomes in the Definitive Radiation Treatment of Anal Cancer Between HIV-Positive and HIV-Negative Patients.

BACKGROUND: Anal squamous cell carcinoma (ASCC) is uncommon, yet seen more frequently in the setting of the human immunodeficiency virus (HIV). Chemoradiotherapy is the definitive modality of treatment for patients with ASCC; this study examines factors impacting clinical outcomes in a large cohort of HIV-positive and HIV-negative patients. METHODS: A retrospective review was conducted of patients treated for nonmetastatic ASCC at a single institution between 2005 and 2018. Freedom from local recurrence (FFLR), freedom from distant metastasis, and overall survival (OS) were calculated using the Kaplan-Meier method, and univariate and multivariate analysis were performed using the Cox proportional hazards model. RESULTS: During the study period, 111 patients initiated definitive treatment for ASCC. Median age of the entire cohort was 56.7 years (interquartile range, 51.5-63.5), with 52 patients (46.8%) being HIV-positive. At median follow-up of 28.0 months, the 2- and 5-year FFLR were 78.2% (95% confidence interval [CI], 70.4-87.0) and 74.6% (95% CI, 65.8-84.5), respectively. Multivariate analysis revealed time from diagnosis to treatment initiation (median, 8 weeks; hazard ratio, 1.06; 95% CI, 1.03-1.10) to be significantly associated with worse FFLR and OS. HIV-positive patients had a trend toward worse FFLR (log-ranked p = .06). For HIV-positive patients with post-treatment CD4 less than 150 cells per mm3 , there was significantly worse OS (log-ranked p = .015). CONCLUSION: A trend toward worse FFLR was seen in HIV-positive patients, despite similar baseline disease characteristics as HIV-negative patients. Worse FFLR and OS was significantly associated with increased time from diagnosis to treatment initiation. Poorer OS was seen in HIV-positive patients with a post-treatment CD4 count less than 150 cells per mm3 . IMPLICATIONS FOR PRACTICE: Human immunodeficiency virus (HIV)-positive patients with anal squamous cell carcinoma can represent a difficult clinical scenario. Definitive radiation with concurrent chemotherapy is highly effective but can result in significant toxicity and a decrease in CD4 count that could predispose to HIV-related complications. As HIV-positive patients have largely been excluded from prospective clinical trials, this study seeks to provide greater understanding of their outcomes with radiation therapy, potential predictors of worse local control and overall survival, and those most at risk after completion of treatment.

Radiation Therapy in HCC: What Data Exist and What Data Do We Need to Incorporate into Guidelines?

Hepatocellular carcinoma (HCC) is a complex and diverse disease, with choice of treatment dependent on a patient's disease burden, location of disease, underlying liver function, and performance status. While radiation therapy (RT) was historically omitted from treatment algorithms, immense technological advances over the past several decades have enabled introduction of RT as an effective and safe treatment option for patients with HCC. Growing prospective and retrospective evidence supports the use of RT, particularly stereotactic body radiotherapy (SBRT), for a wide range of indications in HCC from locally advanced unresectable disease to bridge therapy for liver transplant candidates. SBRT is associated with excellent local control, even for patients refractory to or ineligible for other forms of locoregional therapy. Treatment is well-tolerated and associated with low rates of severe toxicity. Randomized trials are needed to define the role of SBRT in HCC treatment relative to other established locoregional treatments.

Mechanical stretch upregulates connexin43 in human trabecular meshwork cells.

BACKGROUND: Primary open angle glaucoma (POAG) patients have hallmark increases in intraocular pressure (IOP) and noted dysfunction of the trabecular meshwork (TM). Connexin43 (Cx43) is a gap junction widely expressed on the TM that is important for intercellular communication. The human gene is known as gap junction alpha-1 (GJA1). Since the role of Cx43 in the TM is not fully understood, we set out to determine the effect of excess mechanical stretch on cultured human trabecular meshwork cells (hTMCs) and to specifically investigate the effect of stretch on Cx43 expression and function. METHODS: Primary hTMCs were cultured and subjected to 48 hours of 15% cyclic mechanical stretch at a frequency of 1 Hz. Levels of apoptosis and necrosis secondary to stretch were investigated using colorimetric assays. The effect of stretch on gap junction Cx43 and GJA1 was investigated by RT-PCR, immunoblotting and immunofluorescence. The migration of Lucifer Yellow dye was used to assess intercellular communication. RESULTS: Stretch significantly increased the rates of apoptosis and necrosis in hTMCs. The increased rate of injury in stretched hTMCs was further associated with significant upregulation of GJA1 mRNA and Cx43 protein. Upregulation of Cx43 protein was concomitant to increased intercellular communication. CONCLUSIONS: We have shown stretch to increase GJA1 gene and Cx43 protein expression, as well as intercellular communication. We have further shown stretch to be injurious to hTMCs. Upregulation of Cx43 in the hTM subsequent to stretch is a novel finding, which may be useful in elucidating the mechanism of TM injury in POAG patients.

Quantification of liver function by linearization of a two-compartment model of gadoxetic acid uptake using dynamic contrast-enhanced magnetic resonance imaging.

Dynamic gadoxetic acid-enhanced magnetic resonance imaging (MRI) allows the investigation of liver function through the observation of the perfusion and uptake of contrast agent in the parenchyma. Voxel-by-voxel quantification of the contrast uptake rate (k1 ) from dynamic gadoxetic acid-enhanced MRI through the standard dual-input, two-compartment model could be susceptible to overfitting of variance in the data. The aim of this study was to develop a linearized, but more robust, model. To evaluate the estimated k1 values using this linearized analysis, high-temporal-resolution gadoxetic acid-enhanced MRI scans were obtained in 13 examinations, and k1 maps were created using both models. Comparison of liver k1 values estimated from the two methods produced a median correlation coefficient of 0.91 across the 12 scans that could be used. Temporally sparse clinical MRI data with gadoxetic acid uptake were also employed to create k1 maps of 27 examinations using the linearized model. Of 20 scans, the created k1 maps were compared with overall liver function as measured by indocyanine green (ICG) retention, and yielded a correlation coefficient of 0.72. In the 27 k1 maps created via the linearized model, the mean liver k1 value was 3.93 ± 1.79 mL/100 mL/min, consistent with previous studies. The results indicate that the linearized model provides a simple and robust method for the assessment of the rate of contrast uptake that can be applied to both high-temporal-resolution dynamic contrast-enhanced MRI and typical clinical multiphase MRI data, and that correlates well with the results of both two-compartment analysis and independent whole liver function measurements.

Cost-effectiveness of Stereotactic Body Radiation Therapy versus Radiofrequency Ablation for Hepatocellular Carcinoma: A Markov Modeling Study.

Purpose To assess the cost-effectiveness of stereotactic body radiation therapy (SBRT) versus radiofrequency ablation (RFA) for patients with inoperable localized hepatocellular carcinoma (HCC) who are eligible for both SBRT and RFA. Materials and Methods A decision-analytic Markov model was developed for patients with inoperable, localized HCC who were eligible for both RFA and SBRT to evaluate the cost-effectiveness of the following treatment strategies: (a) SBRT as initial treatment followed by SBRT for local progression (SBRT-SBRT), (b) RFA followed by RFA for local progression (RFA-RFA), (c) SBRT followed by RFA for local progression (SBRT-RFA), and (d) RFA followed by SBRT for local progression (RFA-SBRT). Probabilities of disease progression, treatment characteristics, and mortality were derived from published studies. Outcomes included health benefits expressed as discounted quality-adjusted life years (QALYs), costs in U.S. dollars, and cost-effectiveness expressed as an incremental cost-effectiveness ratio. Deterministic and probabilistic sensitivity analysis was performed to assess the robustness of the findings. Results In the base case, SBRT-SBRT yielded the most QALYs (1.565) and cost $197 557. RFA-SBRT yielded 1.558 QALYs and cost $193 288. SBRT-SBRT was not cost-effective, at $558 679 per QALY gained relative to RFA-SBRT. RFA-SBRT was the preferred strategy, because RFA-RFA and SBRT-RFA were less effective and more costly. In all evaluated scenarios, SBRT was preferred as salvage therapy for local progression after RFA. Probabilistic sensitivity analysis showed that at a willingness-to-pay threshold of $100 000 per QALY gained, RFA-SBRT was preferred in 65.8% of simulations. Conclusion SBRT for initial treatment of localized, inoperable HCC is not cost-effective. However, SBRT is the preferred salvage therapy for local progression after RFA. © RSNA, 2017 Online supplemental material is available for this article.

Neoadjuvant stereotactic body radiation therapy, capecitabine, and liver transplantation for unresectable hilar cholangiocarcinoma.

Hilar cholangiocarcinoma (CCA) is a difficult malignancy to treat surgically because of its anatomical location and its frequent association with primary sclerosing cholangitis. Neoadjuvant chemoradiotherapy followed by liver transplantation in lymph node-negative patients has been advanced by select liver transplant centers for the treatment of patients with unresectable disease. This approach has most commonly used external-beam radiotherapy in combination with biliary brachytherapy and 5-fluorouracil-based chemotherapy. Our center recently embarked on a protocol using stereotactic body radiation therapy (SBRT) followed by capecitabine in lymph node-negative patients until liver transplantation. We, therefore, retrospectively determined the tolerability and pathological response in this pilot study. During a 3-year period, 17 patients with unresectable hilar CCA were evaluated for treatment under this protocol. In all, 12 patients qualified for neoadjuvant therapy and were treated with SBRT (50-60 Gy in 3-5 fractions over the course of 2 weeks). After 1 week of rest, capecitabine was initiated at 1330 mg/m(2) /day, and it was continued until liver transplantation. During neoadjuvant therapy, there were 35 adverse events in all, with cholangitis and palmar-plantar erythrodysesthesia being the most common. Capecitabine dose reductions were required on 5 occasions. Ultimately, 9 patients were listed for transplantation, and 6 patients received a liver transplant. The explant pathology of hilar tumors showed at least a partial treatment response in 5 patients, with extensive tumor necrosis and fibrosis noted. Additionally, high apoptotic indices and low proliferative indices were measured during histological examinations. Eleven transplant-related complications occurred, and the 1-year survival rate after transplantation was 83%. In this pilot study, neoadjuvant therapy with SBRT, capecitabine, and liver transplantation for unresectable CCA demonstrated acceptable tolerability. Further studies will determine the overall future efficacy of this therapy.

Pancreatic adenocarcinoma, version 2.2014: featured updates to the NCCN guidelines.

The NCCN Guidelines for Pancreatic Adenocarcinoma discuss the diagnosis and management of adenocarcinomas of the exocrine pancreas and are intended to assist with clinical decision-making. These NCCN Guidelines Insights summarize major discussion points from the 2014 NCCN Pancreatic Adenocarcinoma Panel meeting. The panel discussion focused mainly on the management of borderline resectable and locally advanced disease. In particular, the panel discussed the definition of borderline resectable disease, role of neoadjuvant therapy in borderline disease, role of chemoradiation in locally advanced disease, and potential role of newer, more active chemotherapy regimens in both settings.