Fiducial markers coupled with 3D PET/CT offer more accurate radiation treatment delivery for locally advanced esophageal cancer

Abstract

Background and aims The role of three-dimensional positron emission tomography/computed tomography (3 D PET/CT) in esophageal tumors that move with respiration and have potential for significant mucosal inflammation is unclear. The aim of this study was to determine the correlation between gross tumor volumes derived from 3 D PET/CT and endoscopically placed fiducial markers. Methods This was a retrospective, IRB approved analysis of 40 patients with esophageal cancer with fiducials implanted and PET/CT. The centroid of each fiducial was identified on PET/CT images. Distance between tumor volume and fiducials was measured using axial slices. Image features were extracted and tested for pathologic response predictability. Results The median adaptively calculated threshold value of the standardized uptake value (SUV) to define the metabolic tumor volume (MTV) border was 2.50, which corresponded to a median 23 % of the maximum SUV. The median distance between the inferior fiducial centroid and MTV was – 0.60 cm (– 3.9 to 2.7 cm). The median distance between the superior fiducial centroid and MTV was 1.25 cm (– 4.2 to 6.9 cm). There was no correlation between MTV-to-fiducial distances greater than 2 cm and the gastroenterologist who performed the fiducial implantation. Eccentricity demonstrated statistically significant correlations with pathologic response. Conclusions There was a stronger correlation between inferior fiducial location and MTV border compared to the superior extent. The etiology of the discordance superiorly is unclear, potentially representing benign secondary esophagitis, presence of malignant nodes, inflammation caused by technical aspects of the fiducial placement itself, or potential submucosal disease. Given the concordance inferiorly and the ability to more precisely set up the patient with daily image guidance matching to fiducials, it may be possible to minimize the planning tumor volume (PTV) margin in select patients, thereby, limiting dose to normal structures.

Elevated 18F-NaF uptake in cricoid cartilage in a patient with laryngeal carcinoma

“…Our case illustrates that there is a high uptake of 18 F-FDG in the region near the bone, which is uncertain whether there is any skeletal invasion, so 18 F-NaF PET/CT is critical for the diagnosis of skeletal invasion and 3D PET-CT images are helpful in locating invasion lesions and observing the scope of invasion visually at complex anatomic sites, resulting in further appropriate management [ 11 , 12 ] and that 18 F-NaF PET-CT and 3D PET-CT fusion may be useful to detect occult lesions, such as bone metastases, which have no bone changes. Therefore, 18 F-NaF PET-CT and 3D PET-CT fusion should be kept in mind for differential diagnosis of skeletal invasion.…”

Epidemiology, Diagnosis, Staging and Multimodal Therapy of Esophageal and Gastric Tumors

“…Stable fiducial markers improve the reliability of target volume delineation and assessment of respiratory tumor motion with four-dimensional CT (4D-CT) simulation as a direct visual correlate of tumor extent. Combined with fused PET/CT, fiducials reduce the margins for treatment planning due to improved confidence of accurately defined gross tumor volumes (GTVs) [ 82 ] and facilitate daily image-guided radiation therapy (IGRT) during treatment [ 83 ], see Figure 7 and Figure 8 . Moreover, 4D-CT imaging at simulation has a greater benefit in GEJ and gastric tumors due to the propensity of respiratory motion [ 84 ] and aids in internal target volume construction and planning target volume expansions during treatment planning.…”