Radiation exposure to surgical staff during F-18-FDG-guided cancer surgery

Practice and prospects for PET/CT guided interventions

During the past 10 years, performing real-time molecular imaging with positron emission tomography (PET) in combination with computed tomography (CT) during interventional procedures has undergone rapid development. Keeping in mind the interest of the nuclear medicine readers, an update is provided of the current workflows using real-time PET/CT in percutaneous biopsies and tumor ablations. The clinical utility of PET/CT guided biopsies in cancer patients with lung, liver, lymphoma, and bone tumors are reviewed. Several technological developments, including the introduction of new PET tracers and robotic arms as well as opportunities provided through acquiring radioactive biopsy specimens are briefly reviewed.

Liver Tumor Ablation Procedure Duration and Estimated Patient Radiation Dose: Comparing Positron Emission Tomography/CT and CT Guidance

PURPOSE

To compare procedure duration and patient radiation dose in positron emission tomography/computed tomography (PET/CT) and CT-guided liver tumor ablation procedures.

MATERIALS AND METHODS

In this retrospective, case-control study, 275 patients underwent 368 image-guided ablation procedures to treat 537 tumors. Radiologists used PET/CT guidance for 117 procedures and CT guidance for 251 procedures. PET/CT-guided procedures were performed by one radiologist (C: P.B.S.). All 3 radiologists (A: J.G.S., B: a radiologist who is not an author on this article, and C: P.B.S.) performed CT-guided procedures. Potential confounders included patient demographics, clinical and tumor characteristics, and procedural variables.

RESULTS

The mean duration and estimated patient radiation dose of PET/CT-guided procedures performed by radiologist C were 21.5 ± 4.9 minutes longer and 0.7 ± 2.8 mSv higher than CT-guided procedures performed by all radiologists in an unadjusted comparison. Adjusting for confounding, mean duration and estimated dose of PET/CT-guided procedures performed by radiologist C were 28.3 ± 3.8 minutes longer (P < .0001) and 6.2 ± 2.9 mSv higher (P = .03) than CT-guided procedures performed by the same radiologist. Comparing CT-guided procedures performed by all 3 radiologists, adjusted mean durations and estimated patient doses of procedures by the least experienced radiologist, radiologist A, and the second most experienced radiologist, radiologist B, were 24.2 ± 5.1 (P < .0001) and 18.1 ± 8.9 (P = .04) minutes longer and 13.1 ± 3.7 (P < .001) and 14.5 ± 6.4 (P = .02) mSv higher, respectively, than procedures performed by the most experienced radiologist, radiologist C.

CONCLUSIONS

PET/CT-guided liver ablations had a slightly longer duration with slightly higher estimated patient radiation dose than similar CT-guided liver ablations. Procedure duration and patient dose do not appear to be major impediments to the emerging field of PET/CT-guided tumor ablation.

Intraoperative biophotonic imaging systems for image-guided interventions

Biophotonic imaging has revolutionized the operation room by providing surgeons intraoperative image-guidance to diagnose tumors more efficiently and to resect tumors with real-time image navigation. Among many medical imaging modalities, near-infrared (NIR) light is ideal for image-guided surgery because it penetrates relatively deeply into living tissue, while nuclear imaging provides quantitative and unlimited depth information. It is therefore ideal to develop an integrated imaging system by combining NIR fluorescence and gamma-positron imaging to provide surgeons with highly sensitive and quantitative detection of diseases, such as cancer, in real-time without changing the look of the surgical field. The focus of this review is to provide recent progress in intraoperative biophotonic imaging systems, NIR fluorescence imaging and intraoperative nuclear imaging devices, and their future perspectives for image-guided interventions.

Intraoperative Assessment of Tumor Resection Margins in Breast-Conserving Surgery Using 18F-FDG Cerenkov Luminescence Imaging: A First-in-Human Feasibility Study

In early-stage breast cancer, the primary treatment option for most women is breast-conserving surgery (BCS). There is a clear need for more accurate techniques to assess resection margins intraoperatively, because on average 20% of patients require further surgery to achieve clear margins. Cerenkov luminescence imaging (CLI) combines optical and molecular imaging by detecting light emitted by 18F-FDG. Its high-resolution and small size imaging equipment make CLI a promising technology for intraoperative margin assessment. A first-in-human study was conducted to evaluate the feasibility of 18F-FDG CLI for intraoperative assessment of tumor margins in BCS. Methods: Twenty-two patients with invasive breast cancer received 18F-FDG (5 MBq/kg) 45-60 min before surgery. Sentinel lymph node biopsy was performed using an increased 99mTc-nanocolloid activity of 150 MBq to facilitate nodal detection against the γ-probe background signal (cross-talk) from 18F-FDG. The cross-talk and 99mTc dose required was evaluated in 2 lead-in studies. Immediately after excision, specimens were imaged intraoperatively in an investigational CLI system. The first 10 patients were used to optimize the imaging protocol; the remaining 12 patients were included in the analysis dataset. Cerenkov luminescence images from incised BCS specimens were analyzed postoperatively by 2 surgeons blinded to the histopathology results, and mean radiance and margin distance were measured. The agreement between margin distance on CLI and histopathology was assessed. Radiation doses to staff were measured. Results: Ten of the 12 patients had an elevated tumor radiance on CLI. Mean radiance and tumor-to-background ratio were 560 ± 160 photons/s/cm2/sr and 2.41 ± 0.54, respectively. All 15 assessable margins were clear on CLI and histopathology. The agreement in margin distance and interrater agreement was good (κ = 0.81 and 0.912, respectively). Sentinel lymph nodes were successfully detected in all patients. The radiation dose to staff was low; surgeons received a mean dose of 34 ± 15 μSv per procedure. Conclusion: Intraoperative 18F-FDG CLI is a promising, low-risk technique for intraoperative assessment of tumor margins in BCS. A randomized controlled trial will evaluate the impact of this technique on reexcision rates.

Cerenkov luminescence imaging (CLI) for image-guided cancer surgery

Cerenkov luminescence imaging (CLI) is a novel molecular optical imaging technique based on the detection of optical Cerenkov photons emitted by positron emission tomography (PET) imaging agents. The ability to use clinically approved tumour-targeted tracers in combination with small-sized imaging equipment makes CLI a particularly interesting technique for image-guided cancer surgery. The past few years have witnessed a rapid increase in proof-of-concept preclinical studies in this field, and several clinical trials are currently underway. This article provides an overview of the basic principles of Cerenkov radiation and outlines the challenges of CLI-guided surgery for clinical use. The preclinical and clinical trial literature is examined including applications focussed on image-guided lymph node detection and Cerenkov luminescence endoscopy, and the ongoing clinical studies and technological developments are highlighted. By intraoperatively guiding the oncosurgeon towards more accurate and complete resections, CLI has the potential to transform current surgical practice, and improve oncological and cosmetic outcomes for patients.

[PET/CT-guided salvage surgery protocol. Results with ROLL Technique and PET probe]

OBJECTIVE

To assess the value of intraoperatory radioguided probe detection to guide surgical resection of malignant lesions previously detected by (18)F-FDG PET-CT.

MATERIAL

Twelve consecutive patients with suspected tumor recurrence detected by (18)F-FDG PET-CT considered resectable were enrolled in the study. Ultrasound guided fine needle aspiration (FNA) before surgery was performed in 6 patients and CT guided biopsy was performed in 1 patient. In 5 patients with accessible lesions, a radioguided occult lesion localization (ROLL) technique was performed after injection of (99m)Tc-colloid (1.7-2.4 mCi) inside the lesion under ultrasound or CT guidance, pre-operatively. Radioguided surgical detection was then carried out 19-24 hours afterwards using the gamma probe. In 7 patients with non-accessible needle lesions or multiple lesions, 9.5-10.5 mCi of (18)F-FDG were injected 3-5 hours before radioguided surgery using a PET-dedicated probe (Gamma locator DXI-GF&E).

RESULTS

ROLL technique: All lesions injected with nanocolloid were resected (6 lesions in 5 patients, 1 patient with 2 lesions), and recurrence was histologically confirmed. PET probe: Fourteen out of 16 hypermetabolic lesions detected on the PET-CT were resected. One cervical and one mediastinal lymph node in different patients could not be excised. Histological recurrence was confirmed in 12 out of 14 lesions. In one patient, the 2 lymph nodes excised were inflammatory.

CONCLUSIONS

(18)F-FDG PET-CT can be key in deciding surgical approach and appropriate radioguided protocol. When lesions are solitary and easily accessible, ROLL technique seems the method of choice. PET probe is more adequate for less accessible lesions.

Intraoperative radiation exposure with the use of (18)F-FDG-guided thyroid cancer surgery

Radio-guided surgery is an established means for surgeons to identify a target of interest for biopsy or excision. This technique is used for a variety of malignancies as well as minimally invasive parathyroid surgery. The primary radionuclide used for these procedures is technetium-99m (Tc-99m), but others have been used. Use of (18)fluorine-fluorodeoxyglucose ((18)F-FDG) in oncology has proliferated. This has created the opportunity to use (18)F-FDG as a potential radio tracer in the operating room. A pilot study of three patients with non-iodine avid thyroid cancers undergoing (18)F-FDG-guided revision thyroid cancer surgery is reported. Radiation exposure to operating room personnel was measured. Radiation exposure to the surgeon and staff members of an operating room is well below the limits of the National Regulatory Commission. Therefore, utilization of this radiopharmaceutical intraoperatively should not be limited in the future because of concern regarding exposure of operating room personnel to radiation.

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.

Comprehensive evaluation of occupational radiation exposure to intraoperative and perioperative personnel from 18F-FDG radioguided surgical procedures

PURPOSE

The purpose of the current study was to comprehensively evaluate occupational radiation exposure to all intraoperative and perioperative personnel involved in radioguided surgical procedures utilizing (18)F-fluorodeoxyglucose ((18)F-FDG).

METHODS

Radiation exposure to surgeon, anesthetist, scrub technologist, circulating nurse, preoperative nurse, and postoperative nurse, using aluminum oxide dosimeters read by optically stimulated luminescence technology, was evaluated during ten actual radioguided surgical procedures involving administration of (18)F-FDG.

RESULTS

Mean patient dosage of (18)F-FDG was 699 +/- 181 MBq (range 451-984). Mean time from (18)F-FDG injection to initial exposure of personnel to the patient was shortest for the preoperative nurse (75 +/- 63 min, range 0-182) followed by the circulating nurse, anesthetist, scrub technologist, surgeon, and postoperative nurse. Mean total time of exposure of the personnel to the patient was longest for the anesthetist (250 +/- 128 min, range 69-492) followed by the circulating nurse, scrub technologist, surgeon, postoperative nurse, and preoperative nurse. Largest deep dose equivalent per case was received by the surgeon (164 +/- 135 microSv, range 10-580) followed by the anesthetist, scrub technologist, postoperative nurse, circulating nurse, and preoperative nurse. Largest deep dose equivalent per hour of exposure was received by the preoperative nurse (83 +/- 134 microSv/h, range 0-400) followed by the surgeon, anesthetist, postoperative nurse, scrub technologist, and circulating nurse.

CONCLUSION

On a per case basis, occupational radiation exposure to intraoperative and perioperative personnel involved in (18)F-FDG radioguided surgical procedures is relatively small. Development of guidelines for monitoring occupational radiation exposure in (18)F-FDG cases will provide reassurance and afford a safe work environment for such personnel.