Nicolas Peguret

Reduction of Respiratory Motion During PET/CT by Pulsatile-Flow Ventilation: A First Clinical Evaluation

Respiratory motion negatively affects PET/CT image quality and quantitation. A novel Pulsatile-Flow Ventilation (PFV) system reducing respiratory motion was applied in spontaneously breathing patients to induce sustained apnea during PET/CT. Methods: Four patients (aged 65 ± 14 y) underwent PET/CT for pulmonary nodule staging (mean, 11 ± 7 mm; range, 5–18 mm) at 63 ± 3 min after 18F-FDG injection and then at 47 ± 7 min afterward, during PFV-induced apnea (with imaging lasting ≥8.5 min). Anterior–posterior thoracic amplitude, SUVmax, and SUVpeak (SUVmean in a 1-cm-diameter sphere) were compared. Results: PFV PET/CT reduced thoracic amplitude (80%), increased mean lesion SUVmax (29%) and SUVpeak (11%), decreased lung background SUVpeak (25%), improved lesion detectability, and increased SUVpeak lesion-to-background ratio (54%). On linear regressions, SUVmax and SUVpeak significantly improved (by 35% and 23%, respectively; P ≤ 0.02). Conclusion: PFV-induced apnea reduces thoracic organ motion and increases lesion SUV, detectability, and delineation, thus potentially affecting patient management by improving diagnosis, prognostication, monitoring, and external-radiation therapy planning.

Linear-Endobronchial Ultrasound-guided Insertion of a Fiducial Marker: A New Tool for Tracking Central Lesions.

Stereotactic body radiotherapy (SBRT) is an effective method for the treatment of localized primary lung tumors. Cyberknife, a highly accurate SBRT technique, follows the target during respiratory cycles using a metallic fiducial marker (FM) previously inserted into the lesion. Various methods have been described for the placement of an FM in peripheral pulmonary lesions; however, none of these is appropriate for mediastinal or hilar tumors. The placement of FMs in central lesions to achieve accurate SBRT is particularly relevant due to their higher mobility during respiratory and cardiac cycles. Here, we describe the use of linear-endobronchial ultrasound for the insertion of an FM marker in a centrally located metastatic melanoma, thereby allowing subsequent treatment with Cyberknife.

Incidence of skin recurrence after breast cancer surgery.

In a study of interobserver variations in delineating the breast for treatment planning, Reed et al. reported that interobserver differences were smallest at the breast skin surface, owing to the use of an automatically generated external skin contour [1]. Accordingly, the RTOG breast atlas extends the breast/chest wall CTV to the skin [2]. However, including the skin into the breast CTV is in discrepancy with planning studies that reported cropping CTV [3] or PTV to 5 mm [4] or 6 mm under the skin surface [5]. On one hand, including the skin can impact on the need to use a bolus or a skin flash technique [6], with consequently increased risk of skin toxicity. On the other hand, excluding the skin could cause an unwanted underdosage. There is a need to discuss whether the breast’s skin should be a treatment target or not.

Chest-MRI under pulsatile flow ventilation: A new promising technique.

Objectives Magnetic resonance imaging (MRI) of the chest has long suffered from its sensitivity to respiratory and cardiac motion with an intrinsically low signal to noise ratio and a limited spatial resolution. The purpose of this study was to perform chest MRI under an adapted non invasive pulsatile flow ventilation system (high frequency percussive ventilation, HFPV®) allowing breath hold durations 10 to 15 times longer than other existing systems. Methods One volunteer and one patient known for a thymic lesion underwent a chest MRI under ventilation percussion technique (VP-MR). Routinely used sequences were performed with and without the device during three sets of apnoea on inspiration. Results VP-MR was well tolerated in both cases. The mean duration of the thoracic stabilization was 10.5 min (range 8.5–12) and 5.8 min (range 5–6.2) for Volunteer 1 and Patient 1, respectively. An overall increased image quality was seen under VP-MR with a better delineation of the mediastinal lesion for Patient 1. Nodules discovered in Volunteer 1 were confirmed with low dose CT. Conclusion VP-MR was feasible and increased spatial resolution of chest MRI by allowing acquisition at full inspiration during thoracic stabilization approaching prolonged apnoea. This new technique could be of benefit to numerous thoracic disorders.

Sparing healthy lung by focusing the radiation beam flow onto the emphysematous regions in the treatment of lung cancer

Currently, routine radiotherapy (RT) planning for locally advanced lung cancer (LC) does not take into consideration the functional state of the lung. The goal of this study was to determine if it is technically feasible to integrate the sites of pulmonary emphysema (PE) into the RT planning process.