TraceIT hydrogel, injected endoscopically under local anesthesia in an office setting, can be considered a feasible option to precisely map tumor location with margins to facilitate targeted RT. The precise delineation of tumor margins on cone beam CT (CBCT) obtained with TraceIT could significantly improve an oncological outcome with minimal side effects.
Neil F. Mariados, MD, Pat Campbell, PhD, Deborath Zehel, BSc, Christopher M. Pieczonka, MD, David M. Albala, MD, Vladimir Mouraviev, MD, PhD; Associated Medical Professionals of NY, PLLC; Augmenix
Background: Radiation oncologists often combine, or fuse, magnetic resonance (MR) and CT images to improve dose planning and accuracy. However, most markers do not have equivalent visibility on both CT and MR, creating a permanent image artifact in areas of particular interest and limiting their usefulness for image fusion. The TraceIT Tissue Marker (Augmenix, Waltham, MA) is an injectable polyethylene glycol-based hydrogel marker designed to be visible under CT, cone beam CT (CBCT), MR, and ultrasound imaging for 3 months after implantation and then absorbed within 7 months.
Methods: Two patients with muscle-invasive bladder tumor underwent endoscopic injections of TraceIT for tumor localization in preparation for radiotherapy. The first patient was an 80-year-old who had a history of left nephroureterectomy for upper tract urothelial carcinoma 1.5 years ago and was diagnosed with recurrent bladder cancer. Cystoscopy showed a large papillary tumor measuring more than 5 cm located on the posterior wall, which was resected by transurethral resection of bladder tumor (TURBT) and was found to be a high-grade muscle-invasive urothelial carcinoma with lymphatic invasion. Patient declined radical cystectomy and chose combination radiotherapy and chemotherapy. The second patient, a 75-year-old male, was diagnosed with a high-grade muscle-invasive urothelial carcinoma of the bladder located at the right posterior bladder wall. He also elected for chemotherapy combined with radiation therapy. Under local anesthesia (intraurethral 2% lidocaine gel and intravesical 1% lidocaine), a rigid 20 Fr. injection cystoscopy was introduced into the bladder, systematic cystoscopy was performed, and the tumor bed was localized. TraceIT was injected using a 23-gauge needle with 0.3 mL into six locations for the first patient and 0.2–0.3 mL into eight locations for the second patient, placed around the tumor resection bed within 1 cm from the cancer border. A total of 1.8 mL and 2.4 mL of TraceIT tissue marker was injected into the bladder wall for the first and second patients, respectively.
Results: Both patients tolerated the procedure well and immediately underwent a treatment planning CT scan following the injection. The patients were discharged following completion of the planning CT scan. Three days later, intensity-modulated radiation therapy (IMRT) was started on the Varian image-guided linear accelerator using RapidArc technology. The exact outlining of tumor margins on CBCT that was provided with TraceIT hydrogel allowed us to use a targeted boost IMRT regimen that led to cancer remission with minimal toxicity in both cases.
Conclusions: TraceIT hydrogel, injected endoscopically under local anesthesia in an office setting, can be considered a feasible option to precisely map tumor location with margins to facilitate targeted RT. The precise delineation of tumor margins on cone beam CT (CBCT) obtained with TraceIT could significantly improve an oncological outcome with minimal side effects.