Clinical usability of 3D gradient-echo-based ultrashort echo time imaging: Is it enough to facilitate diagnostic decision in real-world practice?

BACKGROUND: With recent advances in magnetic resonance imaging (MRI) technology, the practical role of lung MRI is expanding despite the inherent challenges of the thorax. The purpose of our study was to evaluate the current status of the concurrent dephasing and excitation (CODE) ultrashort echo-time sequence and the T1-weighted volumetric interpolated breath-hold examination (VIBE) sequence in the evaluation of thoracic disease by comparing it with the gold standard computed tomography (CT). METHODS: Twenty-four patients with lung cancer and mediastinal masses underwent both CT and MRI including T1-weighted VIBE and CODE. For CODE images, data were acquired in free breathing and end-expiratory images were reconstructed using retrospective respiratory gating. All images were evaluated through qualitative and quantitative approaches regarding various anatomical structures and lesions (nodule, mediastinal mass, emphysema, reticulation, honeycombing, bronchiectasis, pleural plaque and lymphadenopathy) inside the thorax in terms of diagnostic performance in making specific decisions. RESULTS: Depiction of the lung parenchyma, mediastinal and pleural lesion was not significant different among the three modalities (p > 0.05). Intra-tumoral and peritumoral features of lung nodules were not significant different in the CT, VIBE or CODE images (p > 0.05). However, VIBE and CODE had significantly lower image quality and poorer depiction of airway, great vessels, and emphysema compared to CT (p < 0.05). Image quality of central airways and depiction of bronchi were significantly better in CODE than in VIBE (p < 0.001 and p = 0.005). In contrast, the depiction of the vasculature was better for VIBE than CODE images (p = 0.003). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were significant greater in VIBE than CODE except for SNRlung and SNRnodule (p < 0.05). CONCLUSIONS: Our study showed the potential of CODE and VIBE sequences in the evaluation of localized thoracic abnormalities including solid pulmonary nodules.

Breath-Hold Diving Injuries - A Primer for Medical Providers.

ABSTRACT: Breath-hold divers, also known as freedivers, are at risk of specific injuries that are unique from those of surface swimmers and compressed air divers. Using peer-reviewed scientific research and expert opinion, we created a guide for medical providers managing breath-hold diving injuries in the field. Hypoxia induced by prolonged apnea and increased oxygen uptake can result in an impaired mental state that can manifest as involuntary movements or full loss of consciousness. Negative pressure barotrauma secondary to airspace collapse can lead to edema and/or hemorrhage. Positive pressure barotrauma secondary to overexpansion of airspaces can result in gas embolism or air entry into tissues and organs. Inert gas loading into tissues from prolonged deep dives or repetitive shallow dives with short surface intervals can lead to decompression sickness. Inert gas narcosis at depth is commonly described as an altered state similar to that experienced by compressed air divers. Asymptomatic cardiac arrhythmias are common during apnea, normally reversing shortly after normal ventilation resumes. The methods of glossopharyngeal breathing (insufflation and exsufflation) can add to the risk of pulmonary overinflation barotrauma or loss of consciousness from decreased cardiac preload. This guide also includes information for medical providers who are tasked with providing medical support at an organized breath-hold diving event with a list of suggested equipment to facilitate diagnosis and treatment outside of the hospital setting.

A comparative study in left-sided breast cancer treated with moderate deep inspiratory breath hold versus free breathing.

BACKGROUND: The moderate deep inspiratory breath hold (mDIBH) is a modality famed for cardiac sparing. Prospective studies based on this are few from the eastern part of the world and India. We intend to compare the dosimetry between mDIBH and free-breathing (FB) plans. METHODS: Thirty-two locally advanced left breast cancer patients were taken up for the study. All patients received a dose of 50 Gy in 25 fractions to the chest wall/intact breast, followed by a 10-Gy boost to the lumpectomy cavity in the case of breast conservation surgery. All the patients were treated in mDIBH using active breath coordinator (ABC). The data from the two dose volume histograms were compared regarding plan quality and the doses received by the organs at risk. Paired t-test was used for data analysis. RESULTS: The dose received by the heart in terms of V5, V10, and V30 (4.55% vs 8.39%) and mean dose (4.73 Gy vs 6.74 Gy) were statistically significant in the ABC group than that in the FB group (all p-values < 0.001). Also, the dose received by the LADA in terms of V30 (19.32% vs 24.87%) and mean dose (32.99 Gy vs 46.65 Gy) were significantly less in the ABC group. The mean treatment time for the ABC group was 20 min, while that for the free-breathing group was 10 min. CONCLUSIONS: Incorporating ABC-mDIBH for left-sided breast cancer radiotherapy significantly reduces the doses received by the heart, LADA, and left and right lung, with no compromise in plan quality but with an increase in treatment time.

Arterial Gas Embolism in Breath-Hold Diver.

An arterial gas embolism (AGE) is a potentially fatal complication of scuba diving that is related to insufficient exhalation during ascent. During breath-hold diving, an arterial gas embolism is unlikely because the volume of gas in the lungs generally cannot exceed the volume at the beginning of the dive. However, if a diver breathes from a gas source at any time during the dive, they are at risk for an AGE or other pulmonary overinflation syndromes (POIS). In this case report, a breath-hold diver suffered a suspected AGE due to rapidly ascending without exhalation following breathing from an air pocket at approximately 40 feet.

Dive Hazards: Barotrauma, Flora, Fauna, Equipment, and Free Diving.

ABSTRACT: Present-day diving comes in various forms, from utilizing sophisticated diving equipment to relying solely on one's ability to hold their breath. The diver and physician must be aware of the many common medical conditions and environmental considerations of this unique activity. While barotrauma remains the most common dive-related injury, injuries and accidents also are related to diving equipment-related accidents and exposure to marine flora and fauna. In addition, breath-hold diving, which includes free diving, snorkeling, and tasks, is an activity humans have done for thousands of years for recreation or survival. This article will update the dangers of diving and methods to prevent or treat injuries.

Experimental demonstration of real-time cardiac physiology-based radiotherapy gating for improved cardiac radioablation on an MR-linac.

BACKGROUND: Cardiac radioablation is a noninvasive stereotactic body radiation therapy (SBRT) technique to treat patients with refractory ventricular tachycardia (VT) by delivering a single high-dose fraction to the VT isthmus. Cardiorespiratory motion induces position uncertainties resulting in decreased dose conformality. Electocardiograms (ECG) are typically used during cardiac MRI (CMR) to acquire images in a predefined cardiac phase, thus mitigating cardiac motion during image acquisition. PURPOSE: We demonstrate real-time cardiac physiology-based radiotherapy beam gating within a preset cardiac phase on an MR-linac. METHODS: MR images were acquired in healthy volunteers (n = 5, mean age = 29.6 years, mean heart-rate (HR) = 56.2 bpm) on the 1.5 T Unity MR-linac (Elekta AB, Stockholm, Sweden) after obtaining written informed consent. The images were acquired using a single-slice balance steady-state free precession (bSSFP) sequence in the coronal or sagittal plane (TR/TE = 3/1.48 ms, flip angle = 48 ∘ $^{\circ }$ , SENSE = 1.5, field-of-view = 400 × 207 $\text{field-of-view} = {400}\times {207}$ mm 2 ${\text{mm}}^{2}$ , voxel size = 3 × 3 × 15 $3\times 3\times 15$ mm 3 ${\rm mm}^{3}$ , partial Fourier factor = 0.65, frame rate = 13.3 Hz). In parallel, a 4-lead ECG-signal was acquired using MR-compatible equipment. The feasibility of ECG-based beam gating was demonstrated with a prototype gating workflow using a Quasar MRI4D motion phantom (IBA Quasar, London, ON, Canada), which was deployed in the bore of the MR-linac. Two volunteer-derived combined ECG-motion traces (n = 2, mean age = 26 years, mean HR = 57.4 bpm, peak-to-peak amplitude = 14.7 mm) were programmed into the phantom to mimic dose delivery on a cardiac target in breath-hold. Clinical ECG-equipment was connected to the phantom for ECG-voltage-streaming in real-time using research software. Treatment beam gating was performed in the quiescent phase (end-diastole). System latencies were compensated by delay time correction. A previously developed MRI-based gating workflow was used as a benchmark in this study. A 15-beam intensity-modulated radiotherapy (IMRT) plan ( 1 × 6.25 ${1}\times {6.25}$ Gy) was delivered for different motion scenarios onto radiochromic films. Next, cardiac motion was then estimated at the basal anterolateral myocardial wall via normalized cross-correlation-based template matching. The estimated motion signal was temporally aligned with the ECG-signal, which were then used for position- and ECG-based gating simulations in the cranial-caudal (CC), anterior-posterior (AP), and right-left (RL) directions. The effect of gating was investigated by analyzing the differences in residual motion at 30, 50, and 70% treatment beam duty cycles. RESULTS: ECG-based (MRI-based) beam gating was performed with effective duty cycles of 60.5% (68.8%) and 47.7% (50.4%) with residual motion reductions of 62.5% (44.7%) and 43.9% (59.3%). Local gamma analyses (1%/1 mm) returned pass rates of 97.6% (94.1%) and 90.5% (98.3%) for gated scenarios, which exceed the pass rates of 70.3% and 82.0% for nongated scenarios, respectively. In average, the gating simulations returned maximum residual motion reductions of 88%, 74%, and 81% at 30%, 50%, and 70% duty cycles, respectively, in favor of MRI-based gating. CONCLUSIONS: Real-time ECG-based beam gating is a feasible alternative to MRI-based gating, resulting in improved dose delivery in terms of high γ -pass $\gamma {\text{-pass}}$ rates, decreased dose deposition outside the PTV and residual motion reduction, while by-passing cardiac MRI challenges.

Protocol of a phase II study to evaluate the efficacy and safety of deep-inspiration breath-hold daily online adaptive radiotherapy for centrally located lung tumours (PUDDING study).

BACKGROUND: Centrally located lung tumours present a challenge because of their tendency to exhibit symptoms such as airway obstruction, atelectasis, and bleeding. Surgical resection of these tumours often requires sacrificing the lungs, making definitive radiotherapy the preferred alternative to avoid pneumonectomy. However, the proximity of these tumours to mediastinal organs at risk increases the potential for severe adverse events. To mitigate this risk, we propose a dual-method approach: deep inspiration breath-hold (DIBH) radiotherapy combined with adaptive radiotherapy. The aim of this single-centre, single-arm phase II study is to investigate the efficacy and safety of DIBH daily online adaptive radiotherapy. METHODS: Patients diagnosed with centrally located lung tumours according to the International Association for the Study of Lung Cancer recommendations, are enrolled and subjected to DIBH daily online adaptive radiotherapy. The primary endpoint is the one-year cumulative incidence of grade 3 or more severe adverse events, as classified by the Common Terminology Criteria for Adverse Events (CTCAE v5.0). DISCUSSION: Delivering definitive radiotherapy for centrally located lung tumours presents a dilemma between ensuring optimal dose coverage for the planning target volume and the associated increased risk of adverse events. DIBH provides measurable dosimetric benefits by increasing the normal lung volume and distancing the tumour from critical mediastinal organs at risk, leading to reduced toxicity. DIBH adaptive radiotherapy has been proposed as an adjunct treatment option for abdominal and pelvic cancers. If the application of DIBH adaptive radiotherapy to centrally located lung tumours proves successful, this approach could shape future phase III trials and offer novel perspectives in lung tumour radiotherapy. TRIAL REGISTRATION: Registered at the Japan Registry of Clinical Trials (jRCT; https://jrct.niph.go.jp/ ); registration number: jRCT1052230085 ( https://jrct.niph.go.jp/en-latest-detail/jRCT1052230085 ).

3D whole heart k-space-based super-resolution cardiac T1 mapping using rotated stacks.

Objective. To provide three-dimensional (3D) whole-heart high-resolution isotropic cardiac T1 maps using a k-space-based through-plane super-resolution reconstruction (SRR) with rotated multi-slice stacks.Approach. Due to limited SNR and cardiac motion, often only 2D T1 maps with low through-plane resolution (4-8 mm) can be obtained. Previous approaches used SRR to calculate 3D high-resolution isotropic cardiac T1 maps. However, they were limited to the ventricles. The proposed approach acquires rotated stacks in long-axis orientation with high in-plane resolution but low through-plane resolution. This results in radially overlapping stacks from which high-resolution T1 maps of the whole heart are reconstructed using a k-space-based SRR framework considering the complete acquisition model. Cardiac and residual respiratory motion between different breath holds is estimated and incorporated into the reconstruction. The proposed approach was evaluated in simulations and phantom experiments and successfully applied to ten healthy subjects.Main results. 3D T1 maps of the whole heart were obtained in the same acquisition time as previous methods covering only the ventricles. T1 measurements were possible even for small structures, such as the atrial wall. The proposed approach provided accurate (P> 0.4;R2> 0.99) and precise T1 values (SD of 64.32 ± 22.77 ms in the proposed approach, 44.73 ± 31.9 ms in the reference). The edge sharpness of the T1 maps was increased by 6.20% and 4.73% in simulation and phantom experiments, respectively. Contrast-to-noise ratios between the septum and blood pool increased by 14.50% inin vivomeasurements with a k-space compared to an image-space-based SRR.Significance. The proposed approach provided whole-heart high-resolution 1.3 mm isotropic T1 maps in an overall acquisition time of approximately three minutes. Small structures, such as the atrial and right ventricular walls, could be visualized in the T1 maps.

High-resolution free-breathing hepatobiliary phase MRI of the liver using XD-GRASP.

PURPOSE: To evaluate the performance of high-resolution free-breathing (FB) hepatobiliary phase imaging of the liver using the eXtra-Dimension Golden-angle RAdial Sparse Parallel (XD-GRASP) MRI technique. METHODS: Fifty-eight clinical patients (41 males, mean age = 52.9 ± 12.9) with liver lesions who underwent dynamic contrast-enhanced MRI with a liver-specific contrast agent were prospectively recruited for this study. Both breath-hold volumetric interpolated examination (BH-VIBE) imaging and FB imaging were performed during the hepatobiliary phase. FB images were acquired using a stack-of-stars golden-angle radial sequence and were reconstructed using the XD-GRASP method. Two experienced radiologists blinded to acquisition schemes independently scored the overall image quality, liver edge sharpness, hepatic vessel clarity, conspicuity of lesion, and overall artifact level of each image. The non-parametric paired two-tailed Wilcoxon signed-rank test was used for statistical analysis. RESULTS: Compared to BH-VIBE images, XD-GRASP images received significantly higher scores (P < 0.05) for the liver edge sharpness (4.83 ± 0.45 vs 4.29 ± 0.46), the hepatic vessel clarity (4.64 ± 0.67 vs 4.15 ± 0.56) and the conspicuity of lesion (4.75 ± 0.53 vs 4.31 ± 0.50). There were no significant differences (P > 0.05) between BH-VIBE and XD-GRASP images for the overall image quality (4.61 ± 0.50 vs 4.74 ± 0.47) and the overall artifact level (4.13 ± 0.44 vs 4.05 ± 0.61). CONCLUSION: Compared to conventional BH-VIBE MRI, FB radial acquisition combined with XD-GRASP reconstruction facilitates higher spatial resolution imaging of the liver during the hepatobiliary phase. This enhancement can significantly improve the visualization and evaluation of the liver.

Effects of hyperventilation on repeated breath-holding while in a fasting state: do risks outweigh the benefits?

Breath-holding preceded by either an overnight fast or hyperventilation has been shown to potentiate the risk of a hypoxic blackout. However, no study has explored the combined effects of fasting and hyperventilation on apneic performance and associated physiological responses. Nine nondivers (8 males) attended the laboratory on two separate occasions (≥48 h apart), both after a 12-h overnight fast. During each visit, a hyperoxic rebreathing trial was performed followed by three repeated maximal static apneas preceded by either normal breathing (NORM) or a 30-s hyperventilation (HYPER). Splenic volume, hematology, cardiovascular, and respiratory variables were monitored. There were no interprotocol differences at rest or during hyperoxic rebreathing for any variable (P ≥ 0.09). On nine occasions (8 in HYPER), the subjects reached our safety threshold (oxygen saturation 65%) and were asked to abort their apneas, with the preponderance of these incidents (6 of 9) occurring during the third repetition. Across the sequential attempts, longer apneas were recorded in HYPER [median(range), 220(123-324) s vs. 185(78-296) s, P ≤ 0.001], with involuntary breathing movements occurring later [134(65-234) s vs. 97(42-200) s, P ≤ 0.001] and end-apneic partial end-tidal pressures of oxygen (PETO2) being lower (P ≤ 0.02). During the final repetition, partial end-tidal pressure of carbon dioxide [(PETCO2), 6.53 ± 0.46 kPa vs. 6.01 ± 0.45 kPa, P = 0.005] was lower in HYPER. Over the serial attempts, preapneic tidal volume was gradually elevated [from apnea 1 to 3, by 0.26 ± 0.24 L (HYPER) and 0.28 ± 0.30 L (NORM), P ≤ 0.025], with a correlation noted with preapneic PETCO2 (r = -0.57, P < 0.001) and PETO2 (r = 0.76, P < 0.001), respectively. In a fasted state, preapnea hyperventilation compared with normal breathing leads to longer apneas but may increase the susceptibility to a hypoxic blackout.NEW & NOTEWORTHY This study shows that breath-holds (apneas) preceded by a 12-h overnight fast coupled with a 30-s hyperventilation as opposed to normal breathing may increase the likelihood of a hypoxic blackout through delaying the excitation of hypercapnic ventilatory sensory chemoreflexes. Evidently, this risk is exacerbated over a series of repeated maximal attempts, possibly due to a shift in preapneic gas tensions facilitated by an unintentional increase in tidal volume breathing.

Intra-patient and inter-observer image quality analysis in liver MRI study with gadoxetic acid using two different multi-arterial phase techniques.

PURPOSE: To evaluate intra-patient and interobserver agreement in patients who underwent liver MRI with gadoxetic acid using two different multi-arterial phase (AP) techniques. METHODS: A total of 154 prospectively enrolled patients underwent clinical gadoxetic acid-enhanced liver MRI twice within 12 months, using two different multi-arterial algorithms: CAIPIRINHA-VIBE and TWIST-VIBE. For every patient, breath-holding time, body mass index, sex, age were recorded. The phase without contrast media and the APs were independently evaluated by two radiologists who quantified Gibbs artefacts, noise, respiratory motion artefacts, and general image quality. Presence or absence of Gibbs artefacts and noise was compared by the McNemar's test. Respiratory motion artefacts and image quality scores were compared using Wilcoxon signed rank test. Interobserver agreement was assessed by Cohen kappa statistics. RESULTS: Compared with TWIST-VIBE, CAIPIRINHA-VIBE images had better scores for every parameter except higher noise score. Triple APs were always acquired with TWIST-VIBE but failed in 37% using CAIPIRINHA-VIBE: 11% have only one AP, 26% have two. Breath-holding time was the only parameter that influenced the success of multi-arterial techniques. TWIST-VIBE images had worst score for Gibbs and respiratory motion artefacts but lower noise score. CONCLUSION: CAIPIRINHA-VIBE images were always diagnostic, but with a failure of triple-AP in 37%. TWIST-VIBE was successful in obtaining three APs in all patients. Breath-holding time is the only parameter which can influence the preliminary choice between CAIPIRINHA-VIBE and TWIST-VIBE algorithm. ADVANCES IN KNOWLEDGE: If the patient is expected to perform good breath-holds, TWIST-VIBE is preferable; otherwise, CAIPIRINHA-VIBE is more appropriate.

Effects of a 6-Week Repeated-Sprint Training With Voluntary Hypoventilation at Low and High Lung Volume on Repeated-Sprint Ability in Female Soccer Players.

PURPOSE: To investigate the effects of repeated-sprint training with voluntary hypoventilation at low (RSH-VHL) and high (RS-VHH) lung volume on repeated-sprint ability (RSA) in female athletes. METHODS: Over a 6-week period, 24 female soccer players completed 12 sessions of repeated 30-m running sprints with end-expiratory breath holding (RSH-VHL, n = 8), end-inspiratory breath holding (RS-VHH, n = 8), or unrestricted breathing (RS-URB, n = 8). Before and after training, a running RSA test consisting of performing 30-m all-out sprints until exhaustion was implemented. RESULTS: From before to after training, the number of sprints completed during the RSA test was increased in both RSH-VHL (19.3 [0.9] vs 22.6 [0.9]; P < .01) and RS-VHH (19.3 [1.5] vs 20.5 [1.7]; P < .01) but not in RS-URB (19.4 [1.3] vs 19.5 [1.7]; P = .67). The mean velocity and the percentage decrement score calculated over sprints 1 to 17 were, respectively, higher (82.2% [1.8%] vs 84.6% [2.1%] of maximal velocity) and lower (23.7% [3.1%] vs 19.4% [3.2%]) in RSH-VHL (P < .01), whereas they remained unchanged in RS-VHH and RS-URB. The mean arterial oxygen saturation recorded during training at the end of the sprints was lower in RSH-VHL (92.1% [0.4%]) than in RS-VHH (97.3% [0.1%]) and RS-URB (97.8% [0.1%]). CONCLUSIONS: This study shows that female athletes can benefit from the RSH-VHL intervention to improve RSA. The performance gains may have been limited by the short sprinting distance with end-expiratory breath holding, which provoked only moderate hypoxemia. The increase in the number of sprints in RS-VHH seems to show that factors other than hypoxia may have played a role in RSA improvement.

CD8+ T-cell metabolism is related to cerebrovascular reactivity in middle-aged adults.

Cerebrovascular reactivity (CVR) decreases with advancing age, contributing to increased risk of cognitive impairment; however, the mechanisms underlying the age-related decrease in CVR are incompletely understood. Age-related changes to T cells, such as impaired mitochondrial respiration, increased inflammation, likely contribute to peripheral and cerebrovascular dysfunction in animals. However, whether T-cell mitochondrial respiration is related to cerebrovascular function in humans is not known. Therefore, we hypothesized that peripheral T-cell mitochondrial respiration would be positively associated with CVR and that T-cell glycolytic metabolism would be negatively associated with CVR. Twenty middle-aged adults (58 ± 5 yr) were recruited for this study. T cells were separated from peripheral blood mononuclear cells. Cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR, a marker of glycolytic activity) were measured using extracellular flux analysis. CVR was quantified using the breath-hold index (BHI), which reflects the change in blood velocity in the middle-cerebral artery (MCAv) during a 30-s breath-hold. In contrast to our hypothesis, we found that basal OCR in CD8+ T cells (ß = -0.59, R2 = 0.27, P = 0.019) was negatively associated with BHI. However, in accordance with our hypothesis, we found that basal ECAR (ß = -2.20, R2 = 0.29, P = 0.015) and maximum ECAR (ß = -50, R2 = 0.24, P = 0.029) were negatively associated with BHI in CD8+ T cells. There were no associations observed in CD4+ T cells. These associations appeared to be primarily mediated by an association with the pressor response to the breath-hold test. Overall, our findings suggest that CD8+ T-cell respiration and glycolytic activity may influence CVR in humans.NEW & NOTEWORTHY Peripheral T-cell metabolism is related to in vivo cerebrovascular reactivity in humans. Higher glycolytic metabolism in CD8+ T cells was associated with lower cerebrovascular reactivity to a breath-hold in middle-aged adults, which is possibly reflective of a more proinflammatory state in midlife.

Initial validation of a diaphragm tracking system for multiple breath-hold volumetric modulated arc therapy of abdominal tumors: A phantom study.

BACKGROUND: The breath-hold radiotherapy has been increasingly used to mitigate interfractional and intrafractional breathing impact on treatment planning and beam delivery. Previous techniques include body surface measurements or radiopaque metal markers, each having known disadvantages. PURPOSE: We recently proposed a new markerless technique without the disadvantages, where diaphragm was registered between DRR and fluoroscopic x-ray projection images every 180 ms during VMAT delivery. An initial validation of the proposed diaphragm tracking system (DiaTrak) was performed using a chest phantom to evaluate its characteristics. METHODS: Diaphragm registration was performed between DRR and projection streaming kV x-ray images of a chest phantom during VMAT delivery. Streaming data including the projection images and the beam angles were transferred from a linac system to an external PC, where the diaphragm registration accuracy and beam-off latency were measured based on image cross correlation between the DRR and the projection images every 180 ms. RESULTS: It was shown that the average of the beam-off latency was 249.5 ms and the average of the diaphragm registration error was 0.84 mm CONCLUSIONS: Initial validation of the proposed DiaTrak system for multiple breath-hold VMAT of abdominal tumors has been successfully completed with a chest phantom. The resulting beam-off latency and the diaphragm registration error were regarded clinically acceptable.

Spot-scanning proton therapy for early breast cancer in free breathing versus deep inspiration breath-hold.

BACKGROUND AND PURPOSE: Proton therapy for breast cancer is usually given in free breathing (FB). With the use of deep inspiration breath-hold (DIBH) technique, the location of the heart is displaced inferiorly, away from the internal mammary nodes and, thus, the dose to the heart can potentially be reduced. The aim of this study was to explore the potential benefit of proton therapy in DIBH compared to FB for highly selected patients to reduce exposure of the heart and other organs at risk. We aimed at creating proton plans with delivery times feasible with treatment in DIBH. MATERIAL AND METHODS: Sixteen patients with left-sided breast cancer receiving loco-regional proton therapy were included. The FB and DIBH plans were created for each patient using spot-scanning proton therapy with 2-3 fields, robust and single field optimization. For the DIBH plans, minimum monitor unit per spot and spot spacing were increased to reduce treatment delivery time. RESULTS: All plans complied with target coverage constraints. The median mean heart dose was statistically significant reduced from 1.1 to 0.6 Gy relative biological effectiveness (RBE) by applying DIBH. No statistical significant difference was seen for mean dose and V17Gy RBE to the ipsilateral lung. The median treatment delivery time for the DIBH plans was reduced by 27% compared to the FB plans without compromising the plan quality. INTERPRETATION: The median absolute reduction in dose to the heart was limited. Proton treatment in DIBH may only be relevant for a subset of these patients with the largest reduction in heart exposure.

Quantitative analysis of the impact of respiratory state on the heartbeat-induced movements of the heart and its substructures.

PURPOSE: This study seeks to examine the influence of the heartbeat on the position, volume, and shape of the heart and its substructures during various breathing states. The findings of this study will serve as a valuable reference for dose-volume evaluation of the heart and its substructures in radiotherapy for treating thoracic tumors. METHODS: Twenty-three healthy volunteers were enrolled in this study, and cine four-dimensional magnetic resonance images were acquired during periods of end-inspiration breath holding (EIBH), end-expiration breath holding (EEBH), and deep end-inspiration breath holding (DIBH). The MR images were used to delineate the heart and its substructures, including the heart, pericardium, left ventricle (LV), left ventricular myocardium, right ventricle (RV), right ventricular myocardium (RVM), ventricular septum (VS), atrial septum (AS), proximal and middle portions of the left anterior descending branch (pmLAD), and proximal portion of the left circumflex coronary branch (pLCX). The changes in each structure with heartbeat were compared among different respiratory states. RESULTS: Compared with EIBH, EEBH increased the volume of the heart and its substructures by 0.25-3.66%, while the average Dice similarity coefficient (DSC) increased by - 0.25 to 8.7%; however, the differences were not statistically significant. Conversely, the VS decreased by 0.89 mm in the left-right (LR) direction, and the displacement of the RV in the anterior-posterior (AP) direction significantly decreased by 0.76 mm (p < 0.05). Compared with EIBH and EEBH, the average volume of the heart and its substructures decreased by 3.08-17.57% and 4.09-20.43%, respectively, during DIBH. Accordingly, statistically significant differences (p < 0.05) were observed in the volume of the heart, pericardium, LV, RV, RVM, and AS. The average DSC increased by 0-37.04% and - 2.6 to 32.14%, respectively, with statistically significant differences (p < 0.05) found in the right ventricular myocardium and interatrial septum. Furthermore, the displacements under DIBH decreased in the three directions (i.e.,- 1.73 to 3.47 mm and - 0.36 to 2.51 mm). In this regard, the AP displacement of the heart, LV, RV, RVM, LR direction, LV, RV, and AS showed statistically significant differences (p < 0.05). The Hausdorff distance (HD) of the heart and its substructures under the three breathing states are all greater than 11 mm. CONCLUSION: The variations in the displacement and shape alterations of the heart and its substructures during cardiac motion under various respiratory states are significant. When assessing the dose-volume index of the heart and its substructures during radiotherapy for thoracic tumors, it is essential to account for the combined impacts of cardiac motion and respiration.

Feasibility of surface-guidance combined with CBCT for intra-fractional breath-hold motion management during Ethos RT.

PURPOSE: High-quality CBCT and AI-enhanced adaptive planning techniques allow CBCT-guided stereotactic adaptive radiotherapy (CT-STAR) to account for inter-fractional anatomic changes. Studies of intra-fractional respiratory motion management with a surface imaging solution for CT-STAR have not been fully conducted. We investigated intra-fractional motion management in breath-hold Ethos-based CT-STAR and CT-SBRT (stereotactic body non-adaptive radiotherapy) using optical surface imaging combined with onboard CBCTs. METHODS: Ten cancer patients with mobile lower lung or upper abdominal malignancies participated in an IRB-approved clinical trial (Phase I) of optical surface image-guided Ethos CT-STAR/SBRT. In the clinical trial, a pre-configured gating window (± 2 mm in AP direction) on optical surface imaging was used for manually triggering intra-fractional CBCT acquisition and treatment beam irradiation during breath-hold (seven patients for the end of exhalation and three patients for the end of inhalation). Two inter-fractional CBCTs at the ends of exhalation and inhalation in each fraction were acquired to verify the primary direction and range of the tumor/imaging-surrogate (donut-shaped fiducial) motion. Intra-fractional CBCTs were used to quantify the residual motion of the tumor/imaging-surrogate within the pre-configured breath-hold window in the AP direction. Fifty fractions of Ethos RT were delivered under surface image-guidance: Thirty-two fractions with CT-STAR (adaptive RT) and 18 fractions with CT-SBRT (non-adaptive RT). The residual motion of the tumor was quantified by determining variations in the tumor centroid position. The dosimetric impact on target coverage was calculated based on the residual motion. RESULTS: We used 46 fractions for the analysis of intra-fractional residual motion and 43 fractions for the inter-fractional motion analysis due to study constraints. Using the image registration method, 43 pairs of inter-fractional CBCTs and 100 intra-fractional CBCTs attached to dose maps were analyzed. In the motion range study (image registration) from the inter-fractional CBCTs, the primary motion (mean ± std) was 16.6 ± 9.2 mm in the SI direction (magnitude: 26.4 ± 11.3 mm) for the tumors and 15.5 ± 7.3 mm in the AP direction (magnitude: 20.4 ± 7.0 mm) for the imaging-surrogate, respectively. The residual motion of the tumor (image registration) from intra-fractional breath-hold CBCTs was 2.2 ± 2.0 mm for SI, 1.4 ± 1.4 mm for RL, and 1.3 ± 1.3 mm for AP directions (magnitude: 3.5 ± 2.1 mm). The ratio of the actual dose coverage to 99%, 90%, and 50% of the target volume decreased by 0.95 ± 0.11, 0.96 ± 0.10, 0.99 ± 0.05, respectively. The mean percentage of the target volume covered by the prescribed dose decreased by 2.8 ± 4.4%. CONCLUSION: We demonstrated the intra-fractional motion-managed treatment strategy in breath-hold Ethos CT-STAR/SBRT using optical surface imaging and CBCT. While the controlled residual tumor motion measured at 3.5 mm exceeded the predetermined setup value of 2 mm, it is important to note that this motion still fell within the clinically acceptable range defined by the PTV margin of 5 mm. Nonetheless, additional caution is needed with intra-fractional motion management in breath-hold Ethos CT-STAR/SBRT using optical surface imaging and CBCT.

Non-electrocardiogram-gated, free-breathing, off-resonance reduced, high-resolution, whole-heart myocardial T2 * mapping at 3 T within 5 min.

PURPOSE: Widely used conventional 2D T2 * approaches that are based on breath-held, electrocardiogram (ECG)-gated, multi-gradient-echo sequences are prone to motion artifacts in the presence of incomplete breath holding or arrhythmias, which is common in cardiac patients. To address these limitations, a 3D, non-ECG-gated, free-breathing T2 * technique that enables rapid whole-heart coverage was developed and validated. METHODS: A continuous random Gaussian 3D k-space sampling was implemented using a low-rank tensor framework for motion-resolved 3D T2 * imaging. This approach was tested in healthy human volunteers and in swine before and after intravenous administration of ferumoxytol. RESULTS: Spatial-resolution matched T2 * images were acquired with 2-3-fold reduction in scan time using the proposed T2 * mapping approach relative to conventional T2 * mapping. Compared with the conventional approach, T2 * images acquired with the proposed method demonstrated reduced off-resonance and flow artifacts, leading to higher image quality and lower coefficient of variation in T2 *-weighted images of the myocardium of swine and humans. Mean myocardial T2 * values determined using the proposed and conventional approaches were highly correlated and showed minimal bias. CONCLUSION: The proposed non-ECG-gated, free-breathing, 3D T2 * imaging approach can be performed within 5 min or less. It can overcome critical image artifacts from undesirable cardiac and respiratory motion and bulk off-resonance shifts at the heart-lung interface. The proposed approach is expected to facilitate faster and improved cardiac T2 * mapping in those with limited breath-holding capacity or arrhythmias.

The reliability and quality of YouTube videos as a source of breath holding spell.

BACKGROUND: Breath holding spells (BHS) are an important non-epileptic condition that is common in childhood and causes concern to families. YouTube is a powerful social media tool for accessing diseases and information such as BHS in child health. The aim of the study was to measure of the quality and reliability levels of the videos published in English on BHS uploaded on YouTube. METHODS: The key words "infant", "cry", "breath holding spells", holding spells" and "breath spells" were searched on the YouTube on November 14, 2022, in this study. Along with the general features of the videos, their quality and reliability were evaluated according to the global quality score (GQS), mDISCERN score. RESULTS: Fifty-five videos were evaluated. The mDISCERN and GQS scores of the videos in the useful group were higher than those in the misleading group (p < 0.001, p < 0.001). In the useful group, 87.5% of academic institutions and 93.3% of medical doctors (MDs) uploaded high-score GQS videos, while this rate was 16.7% in independent users (p = 0.005). The positive correlation was found between mDISCERN and GQS scores (p < 0.001). CONCLUSION: The majority of YouTube videos on BHS contained useful information with sufficient quality. Professional associations such as universities and academic institutes need to produce better quality videos to provide families/users with more accurate and up-to-date information about BHS. We emphasize that YouTube should analyse videos published in the field of health, especially in the field of pediatrics, such as BHS, with committees consisting of expert health professionals, and publish them after evaluation. YouTube should consider collaborating with professional pediatrics health organizations such as American Academy of Pediatrics (AAP), academic institutes and universities in the field of BHS to produce high-quality videos.

Present and Future Innovations in AI and Cardiac MRI.

Cardiac MRI is used to diagnose and treat patients with a multitude of cardiovascular diseases. Despite the growth of clinical cardiac MRI, complicated image prescriptions and long acquisition protocols limit the specialty and restrain its impact on the practice of medicine. Artificial intelligence (AI)-the ability to mimic human intelligence in learning and performing tasks-will impact nearly all aspects of MRI. Deep learning (DL) primarily uses an artificial neural network to learn a specific task from example data sets. Self-driving scanners are increasingly available, where AI automatically controls cardiac image prescriptions. These scanners offer faster image collection with higher spatial and temporal resolution, eliminating the need for cardiac triggering or breath holding. In the future, fully automated inline image analysis will most likely provide all contour drawings and initial measurements to the reader. Advanced analysis using radiomic or DL features may provide new insights and information not typically extracted in the current analysis workflow. AI may further help integrate these features with clinical, genetic, wearable-device, and "omics" data to improve patient outcomes. This article presents an overview of AI and its application in cardiac MRI, including in image acquisition, reconstruction, and processing, and opportunities for more personalized cardiovascular care through extraction of novel imaging markers.