Abstract
Indocyanine green fluorescent image-guided surgery was developed to identify primary and metastatic nodules of various malignancies. However, currently, surgeons need to identify the fluorescent image on a monitor, which impedes surgical procedures. Herein, we developed a novel projection mapping device that can cast the real-time fluorescent image onto the surface of the targeted organ. We performed surgical resection of a lung metastasis of hepatoblastoma using this technique. The projection mapping technique clearly detected the pulmonary lesion, and no other lesions were identified in the ipsilateral thorax. The patient is well and free of recurrence 2 years after surgery.
INTRODUCTION
Indocyanine green (ICG) is a fluorescent dye that is preferentially taken up by several cancer tissues, such as hepatocellular carcinoma and hepatoblastoma [1]. These tumours can be detected based on the tumour-to-background uptake ratio, allowing them to be imaged with near-infrared light. However, the problem with ICG imaging is that the fluorescent image has to be cast on a separate monitor and requires the operating lights to be turned off, darkening the field. Image overlay surgery is a technique in which an organ map generated from a computed tomography scan is projected onto the body cavity being operated. We have previously used a technique in which images were projected onto the liver tissue, enabling hepatic resection [2]. Now, we, in association with Panasonic AVC Networks Company (Osaka, Japan), have developed a system, the Medical Imaging Projection System (MIPS), that can detect ICG fluorescence even with the operating lights turned on and can then project the image in visible light back onto the organ being operated. Herein, we report on a patient who successfully underwent surgical resection of lung metastases of hepatoblastoma with the MIPS guidance, which is the first use of the projection technique in lung resection.
CASE REPORT
A 3-year-old girl was diagnosed as having hepatoblastoma with multiple lung metastases. After intensive chemotherapy, the lung metastases shrank, and the patient underwent living-donor liver transplantation. However, 2 months later, the patient developed a solitary lung metastasis in the left lower lobe (Fig. 1). Preoperative chest computed tomography revealed a solitary mass; however, the existence of other small lesions in the lungs could not be completely ruled out. After informed consent was obtained from the patient’s parents, ICG fluorescent imaging was applied during the resection of the lung metastatic lesion using the MIPS (Fig. 1). Approximately 24 h before surgery, ICG (Diagnogreen, Daiichi Sankyo, Tokyo, Japan) was administered intravenously at a dosage of 0.5 mg/kg. Intraoperatively, the projection mapping technique clearly revealed the lesion, and no other lesions were detected in the left hemithorax. The MIPS projected the real-time fluorescent image onto the surface of the lung during the surgical procedure (Fig. 2). Left lower segmentectomy was performed with the guidance of ICG fluorescent imaging. The image was projected in real time and moved as the surgeon manipulated the lung. The MIPS also confirmed that no remnant tumour remained after resection. The cut surface of the tumour also emitted ICG fluorescence (Fig. 2). Currently, 2 years postoperatively, the patient is alive without evidence of recurrence.
Preoperative chest computed tomography showing a mass in the left lower lobe (arrow, A). The outlook (B) and the intraoperative view (C) of the new imaging device, the Medical Imaging Projection System.
The Medical Imaging Projection System projecting the real-time fluorescent image on the surface of the lung during surgery (left). The cut surface of the tumour also emitted indocyanine green fluorescence (right).
COMMENTS
The projection mapping technique has previously been introduced into the field of surgery; however, its use in combination with ICG fluorescent image-guided surgery has never been reported in thoracic surgery. In our patient, using this technique, we identified the lesion and project the real-time fluorescent image onto the surface of the lung during the surgical procedure. Furthermore, no other lesions were detected intraoperatively with the MIPS.
The use of ICG fluorescent imaging to detect primary and metastatic malignant tumours is dependent on the clearance of ICG by the tumours [3]. Therefore, it must be kept in mind that not all malignant tumours can be detected with ICG fluorescent imaging. ICG fluorescent imaging has only recently been introduced into video-assisted thoracoscopic surgery, and several clinical studies are being conducted; however, it would also be useful in thoracotomy, such as detection and resection of lung tumours with high avidity for ICG, similar to this case. We aim to replicate this technique in common lung tumours with less avidity for ICG. Although future studies with more cases are required, this system can find invisible and impalpable nodules and/or nodules not evident on computed tomography. Furthermore, this system would be applicable to pulmonary segmentectomy and detection of pulmonary metastasis.
In conclusion, we successfully performed complete surgical resection of a lung metastasis of hepatoblastoma using a new imaging device, the MIPS.
Conflict of interest: none declared.
