ICG videography facilitates interpretation of vascular supply and anatomical landmarks in intramedullary spinal lesions: two case reports

Use of Second Window ICG in spinal cord biopsy of a mildly contrast-enhancing lesion: Technical note and review of the literature

INTRODUCTION

Indocyanine green (ICG) is commonly used to visualize cerebral vasculature, particularly in the management of cerebral aneurysms. There have also been attempts to use ICG for visualization of tumors. Injection of ICG followed by immediate fluorescence microscopy is limited by the short time window for imaging and administration and restricted depth of imaging. Second Window Indocyanine Green (SWIG) addresses these issues by allowing for longer contrast times and the imaging of deeper regions of brain tissue. Biopsy of spinal cord lesions is often difficult for a variety of reasons, including the delicate nature of the tissue and differentiating normal from lesional tissue visually, especially in lesions with heterogeneous enhancement.

METHODS

In this case report, we describe the use of second window ICG to facilitate the visualization of a spinal cord lesion and subsequent biopsy of the lesion.

RESULTS

This patient is a 24-year-old female who had recurrence of a suprasellar germinoma. An MRI of the rest of the neuraxis was performed to assess for the presence of drop metastases. The spinal cord from C2-5 was expanded with areas of patchy enhancement; however, this lesion was asymptomatic. The patient's oncologist requested a biopsy of this lesion to help direct subsequent care of her recurrent germinoma. The day before surgery, the patient had an intravenous injection of ICG dye. She then underwent a C3-5 laminectomy for biopsy of her cervical intramedullary lesion. After opening of the dura, no visible abnormality of the spinal cord could be identified. A Stryker endoscope showed an area of ICG uptake in the cord at approximately the C3-4 level. A midline myelotomy was centered over the ICG demarcated area and several samples were taken for pathology. Final biopsy results determined the lesion to be spinal cord parenchyma with perivascular and intraparenchymal lymphocytes - not consistent with spinal cord tumor or germinoma.

CONCLUSION

Second Window ICG is effective in visualizing otherwise visually unremarkable spinal cord lesions. This technology can facilitate biopsy of these lesions and possibly their surgical resection.

Surgical Treatment of Intramedullary Hemangioblastomas: Current State of Problem (Review)

Intramedullary hemangioblastomas (HAB) refer to very rare highly vascularized vascular spinal cord tumors associated with various neurological disorders. Effective HAB therapy to a greater extent depends on diagnostic accuracy and the absence of intra- and postoperative complications.

The present study is a review of publications concerned with modern diagnostic and therapeutic techniques to control spinal HAB. The authors showed that perfusion computed tomography, computed tomographic angiography, and magnetic resonance angiography can be reasonably used for diagnosis and differentiation in a number of HAB due to their high vascularization. Preoperative embolization significantly reducing intraoperative bleeding risks is highly efficient. Some authors recommend this procedure in case of large lesions and high risks of intraoperative bleeding. The review also considered intraoperative imaging of a tumor and its feeding vessels using indocyanine green providing inspectability over the total tumor resection and clear imaging of tumor vascular architecture. The advantages and restrictions of the mentioned procedures were described.

Intraoperative surveillance of the vertebral artery using indocyanine green angiography and Doppler sonography in craniovertebral junction surgeries

OBJECTIVE

The authors sought to evaluate the usefulness of indocyanine green (ICG) angiography and Doppler sonography for monitoring the vertebral artery (VA) during craniovertebral junction (CVJ) surgery and compare the incidence of VA injury (VAI) between the groups with and without the monitoring of VA using ICG angiography and Doppler sonography.

METHODS

In total, 344 consecutive patients enrolled who underwent CVJ surgery. Surgery was performed without intraoperative VA monitoring tools in 262 cases (control group) and with VA monitoring tools in 82 cases (monitoring group). The authors compared the incidence of VAI between groups. The procedure times of ICG angiography, change of VA flow velocity measured by Doppler sonography, and complication were investigated.

RESULTS

There were 4 VAI cases in the control group, and the incidence of VAI was 1.5%. Meanwhile, there were no VAI cases in the monitoring group. The procedure time of ICG angiography was less than 5 minutes (mean [± SD] 4.6 ± 2.1 minutes) and VA flow velocity was 11.2 ± 4.5 cm/sec. There were several cases in which the surgical method had to be changed depending on the VA monitoring. The combined use of ICG angiography and Doppler sonography was useful not only to monitor VA patency but also to assess the quality of blood flow during CVJ surgery, especially in the high-risk group of patients.

CONCLUSIONS

The combined use of ICG angiography and Doppler sonography enables real-time intraoperative monitoring of the VA by detecting blood flow and flow velocity. As the arteries get closer, they provide auditory and visual feedback to the surgeon. This real-time image guidance could be a useful tool, especially for high-risk patients and inexperienced surgeons, to avoid iatrogenic VAI during any CVJ surgery.

Quantitative Analysis of Near-Infrared Indocyanine Green Videoangiography for Predicting Functional Outcomes After Spinal Intramedullary Ependymoma Resection

BACKGROUND

One of the most critical steps in surgery for spinal intramedullary ependymomas is the resection of small feeding arteries from the anterior spinal artery with anatomical preservation of the normal circulation of the ventral spinal cord.

OBJECTIVE

To quantitatively analyze the microcirculation of the ventral spinal cord by near-infrared indocyanine green videoangiography (ICG-VA) after the spinal intramedullary ependymoma resection.

METHODS

This retrospective study included 12 patients (7 male and 5 female; average age 55.2 years, range 36-79 years). Patients' neurological conditions were assessed based on the modified McCormick functional schema of grade 1 (neurologically normal) to 5 (severe deficit). Postoperative functional assessment was conducted at least 3 months after surgery. Quantitative analysis of vascular flow dynamics was carried out following spinal intramedullary ependymoma resection. Fluorescence intensities were measured and the indocyanine green (ICG) intensity-time curves were analyzed and compared with the functional outcomes after surgery.

RESULTS

Microscopically total or subtotal resection of the intramedullary ependymoma was achieved in all cases. Average peak time on ICG-VA was significantly shorter in the postoperative functional grade 1 to 2 group than in the postoperative functional grade 3 to 5 group, but there was no significant difference in average peak intensity between the 2 groups. Postoperative functional grade and the peak time of ICG, but not peak intensity, appeared correlated.

CONCLUSION

To the best of our knowledge, this is the first report showing that quantitative analysis of ICG-VA may predict functional outcomes after spinal intramedullary ependymoma resection.

Application of indocyanine green video angiography in vascular neurosurgery

Indocyanine green video angiography (ICG-VA) is a non-invasive, easy to use and very useful tool for various neurosurgical procedures. The first application was in neurovascular surgery, because it was born as an intravascular tracer for vessels visualization; this has been really useful in aneurysms, atero-venous malformations (AVMs) and dural fistulas surgery where identification, obliteration or patency of vessels is essential. Introduced in vascular neurosurgery since 2003, ICG-VA applications have broadened over time, both in vascular and in other neurosurgical fields. In 2003 Raabe et al. have been the first to describe the use of ICG-VA for intraoperative assessment of cerebral vascular flow, enabling visualization of vessel patency and aneurysm occlusion during aneurysm surgery. ICG-VA applications in vascular neurosurgery have significantly increased over time including complex aneurysms, bypass, atero-venous malformations (AVM) artero-venous fistulas (AVF), evaluation of cortical perfusion. The procedure can be easily repeated after 5-10 minutes. Adverse reactions are comparable to those of other types of contrast media, with frequencies of 0.05% (hypotension, arrhythmia, or, more rarely, anaphylactic shock) to 0.2% (nausea, pruritus, syncope, or skin eruptions. The aim of the present study was to systematically analyze ICG-VA applications in vascular neurosurgery, highlighting the reported advantages and disadvantages, and discussing future perspectives.

Doxorubicin and indocyanine green loaded superparamagnetic iron oxide nanoparticles with PEGylated phospholipid coating for magnetic resonance with fluorescence imaging and chemotherapy of glioma

Background

Glioma represents the most common malignant brain tumor. Outcomes of surgical resection are often unsatisfactory due to low sensitivity or resolution of imaging methods. Moreover, the use of traditional chemotherapeutics, such as doxorubicin (DOX), is limited due to their low blood-brain barrier (BBB) permeability. Recently, the development of nanotechnology could overcome these obstacles.

Materials and methods

Hydrophobic superparamagnetic iron oxide nanoparticles (SPIO NPs) were prepared with the use of thermal decomposition method. They were coated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG 2000) and DOX using a thin-film hydration method followed by loading of indocyanine green (ICG) into the phospholipid layers. Details regarding the characteristics of NPs were determined. The in vitro biocompatibility and antitumor efficacy were established with the use of MTT assay. In vivo fluorescence and magnetic resonance (MR) imaging were used to evaluate BBB penetration and accumulation of NPs at the tumor site. Antitumor efficacy was evaluated using measures of tumor size, median survival times, body weights, and H&E staining.

Results

The multifunctional NPs generated had an average diameter of 22.9 nm, a zeta potential of -38.19 mV, and were capable of providing a sustained release of DOX. In vitro experiments demonstrated that the SPIO@DSPE-PEG/DOX/ICG NPs effectively enhanced cellular uptake of DOX as compared with that of free DOX. In vivo fluorescence and MR imaging revealed that the NPs not only effectively crossed the BBB but selectively accumulated at the tumor site. Meanwhile, among all groups studied, C6 glioma-bearing rats treated with the NPs exhibited the maximal degree of therapeutic efficacy, including smallest tumor volume, lowest body weight loss, and longest survival times, with no obvious side effects.

Conclusion

These results suggest that the SPIO@DSPE-PEG/DOX/ICG NPs can not only function as a nanoprobe for MR and fluorescence bimodal imaging, but also as a vehicle to deliver chemotherapeutic drugs to the tumor site, to achieve the theranostic treatment of glioma.

Intraoperative FLOW 800 Analysis for Intramedullary Cystic Lesion: A Technical Case Report

BACKGROUND AND IMPORTANCE

During intramedullary lesion surgery, the lesion site and the posterior median sulcus (PMS) should be accurately identified prior to myelotomy to avoid severe injury of the posterior funiculus. However, intramedullary lesions are fundamentally invisible until the myelotomy is performed. Furthermore, the PMS location is frequently unclear due to lesion-induced swelling or distortion of the spinal cord. Intraoperative indocyanine green videoangiography (ICG-VA) followed by FLOW 800 analysis, which shows vascularization of the spinal parenchyma, may provide a solution for these problems in specific cases.

CLINICAL PRESENTATION

A 61-year-old woman suffering from claudication visited our department. Magnetic resonance imaging (MRI) revealed a cystic lesion at the level of Th11. A solid portion was not detected in the T1-weighted images following gadolinium administration. We made a diagnosis of ventriculus terminalis and performed a lesion resection. Prior to opening the PMS, ICG-VA was performed, which revealed an avascular area representing the intramedullary cyst. The PMS was the most avascular area observed in the time-intensity analysis executed using FLOW 800 software (Zeiss, Oberkochen, Germany). Thus, it was helpful in determining the site for myelotomy, which should be performed at the center of the extent of the lesion. The patient was discharged 23 days after the operation, ambulating independently.

CONCLUSION

Intraoperative ICG-VA followed by FLOW 800 analysis was applied to a case of intramedullary cystic lesion. This technique may be helpful in performing safer intramedullary cystic lesion surgery because it enables visualization of the lesion location and confirmation of the PMS.

Transdural Indocyanine Green Videography for Superficial Temporal Artery-to-Middle Cerebral Artery Bypass-Technical Note

BACKGROUND

Neurosurgical application of indocyanine green (ICG) videography before performing a dural opening, known as transdural ICG videography, has been used during surgery of meningiomas associated with venous sinuses as well as cranial and spinal arteriovenous malformations. However, its use for a superficial temporal artery (STA)-to-middle cerebral artery (MCA) bypass has not been reported.

METHODS

We performed a retrospective analysis of medical records of patients who underwent transdural ICG videography during STA-MCA bypass performed between January 2012 and March 2015. The primary outcome was visualization of recipient cortical arteries; secondary outcomes were surgical modifications and complications as well as any adverse events associated with transdural ICG videography.

RESULTS

We analyzed 29 STA-MCA bypass procedures performed in 30 hemispheres with atherosclerotic steno-occlusive disease and found that the proper recipient was identified in 28 hemispheres. Subsequently modified procedures for those were a tailored dural incision and craniotomy correction. No complications associated with ICG administration were encountered; during the postoperative course, transient aphasia was noted in 1 case, chronic subdural hematoma was noted in 1 case, and subdural effusion was noted in 2 cases.

CONCLUSIONS

Transdural ICG videography for atherosclerotic steno-occlusive disease facilitates modifications during STA-MCA bypass procedures. Recognition of the proper recipient cortical arteries before a dural incision allows the neurosurgeon to perform a tailored dural incision and extension of the bone window, although the contribution to surgical outcome has yet to be determined.

Multimodal use of indocyanine green endoscopy in neurosurgery: a single-center experience and review of the literature

During the last 10 years, microscope-integrated indocyanine green fluorescence (m-ICG) has been widely used for assessing real-time blood flow during aneurysm surgery. More recently, an endoscope-integrated indocyanine green fluorescence (e-ICG) has been adopted as a versatile tool during different endoscopic neurosurgical procedures. The purpose of the present report is to evaluate multimodal applications of e-ICG during different endonasal, intraventricular, aneurysm and brain tumor surgeries and provide technical nuances. In addition, we reviewed the literature and identified and compare several overlapping case series of patients treated via an endoscopic integrated indocyanine green fluorescence technique. A total of 40 patients were retrospectively evaluated. Patients were divided into four main groups: (1) endoscopic endonasal approaches (n = 14); (2) ventricular endoscopic approach including patients undergoing third ventriculostomy (n = 8) and tumor biopsy (n = 1); (3) aneurysms surgery (n = 9); and (4) brain parenchymal tumors (n = 8). All patients were successfully treated using the e-ICG dynamic endoscopic visualization, and there were no perioperative complications. Such unique features open up a promising field of applications beyond the use of m-ICG in different surgical field due to the longer duration of e-ICG fluorescence up to 35 ± 7 min. E-ICG represents a new and effective technique for longer real-time visualization of vascular structures preserving normal tissues and functions during different transcranial and endonasal approaches. As the technology and e-ICG resolution improves, the technique has the potential to become a critical tool for different applications in neurosurgery.

Benefits and Limitations of Indocyanine Green Fluorescent Image-Guided Surgery for Spinal Intramedullary Tumors

BACKGROUND

Intraoperative image guidance using near-infrared indocyanine green videoangiography (ICG-VA) has been used to provide real-time angiographic images during vascular or brain tumor surgery, and it is also being used for spine surgery.

OBJECTIVE

To further investigate the benefits and limitations of ICG-VA image-guided surgery for spinal intramedullary tumors through retrospective study.

METHODS

ICG-VA was used in 48 cases that were treated surgically over the past 5 yr. The pathological diagnoses of the tumors included astrocytic tumor, ependymal tumor, cavernous malformation, and hemangioblastoma.

RESULTS

Localization of normal spinal arteries and veins on the dorsal surface of the spinal cord helped the surgeons determine the length or point of myelotomy. Well-demarcated tumor stain was recognized in limited cases of anaplastic or highly vascularized tumors, whereas the location of cavernous malformation was recognized as an avascular area on the dorsal surface of the spinal cord. Feeding arteries and tumor stain were well differentiated from draining veins in dorsal hemangioblastomas, but not in intramedullary deep-seated or ventral tumors. The preservation of small perforating branches of the anterior spinal artery after successful resection of the tumor could be well visualized.

CONCLUSION

ICG-VA can provide real-time information about vascular flow dynamics during the surgery of spinal intramedullary tumors, and it may help surgeons localize the normal circulation of the spinal cord, as well as the feeding arteries and draining veins, especially in highly vascular tumors. However, the benefits of intraoperative ICG-VA might be limited for intramedullary deep-seated or ventral tumors.

Visualization of vascular structure of spinal hemangioblastoma using intraoperative indocyanine green videoangiography and temporary feeder occlusion

BACKGROUND AND PURPOSE

To more safely resect pathological lesions during spinal vascular lesion surgery, it is most important to understand local abnormal hemodynamics in detail. New devices or techniques that make out intraoperative local hemodynamics have been awaited. To introduce a resourceful method, we present a case of spinal hemangioblastoma for which temporary arterial occlusion during near-infrared intraoperative indocyanine green (ICG) videoangiography gives useful assessment of the main and minor feeders easily.

METHODS

A 36-year-old female suffered progressive paresthesia of both lower extremities for 12 months and gait disturbance for 2 weeks. A neurological examination revealed T10 myelopathy. Magnetic resonance imaging (MRI) of the thoracic spine showed an intramedullary tumor at the T8 level and severe spinal cord edema with a flow void in the extended dorsal spinal veins. Spinal angiography showed a hemangioblastoma at the T8 level, with two main feeders and minor feeders.

RESULTS

She underwent total resection of the tumor by a posterior approach. During the intraoperative ICG videoangiography, temporary arterial occlusion of the two main feeders and FLOW(®)800 analysis enabled clear understanding of the vasculature, especially of the two minor feeders. At the 9-month follow-up, her neurological manifestation was partially resolved, and post-operative MRI showed total removal of the tumor and disappearance of the spinal cord edema.

CONCLUSIONS

Temporary clipping of the main feeders during intraoperative ICG videoangiography is very useful for easily determining the minor feeding arteries, and helpful for maintaining normal perfusion of the spinal cord in spinal hemangioblastoma surgery. Furthermore, the FLOW 800 analysis, especially the false color-coded variation, increased our understanding of the hemodynamics.

Indocyanine green videoangiography methodological variations: review

Indocyanine green videoangiography (ICGVA) procedures have become widespread within the spectrum of microsurgical techniques for neurovascular pathologies. We have conducted a review to identify and assess the impact of all of the methodological variations of conventional ICGVA applied in the field of neurovascular pathology that have been published to date in the English literature. A total of 18 studies were included in this review, identifying four primary methodological variants compared to conventional ICGVA: techniques based on the transient occlusion, intra-arterial ICG administration via catheters, use of endoscope system with a filter to collect florescence of ICG, and quantitative fluorescence analysis. These variants offer some possibilities for resolving the limitations of the conventional technique (first, the vascular structure to be analyzed must be exposed and second, vascular filling with ICG follows an additive pattern) and allow qualitatively superior information to be obtained during surgery. Advantages and disadvantages of each procedure are discussed. More case studies with a greater number of patients are needed to compare the different procedures with their gold standard, in order to establish these results consistently.

Intraoperative indocyanine green video-angiography as an aid to the microsurgical treatment of spinal vascular malformations

AIMS AND OBJECTIVES. Intra-operative Indocyanine Green (ICG) video-angiography (ICG-VA) has become an established aid to cerebrovascular surgery. We describe our experience using this technique to define angio-architecture intraoperatively in a range of spinal vascular malformations. METHODS. A retrospective review of notes and imaging was carried out from a prospectively maintained database. Our series comprises 27 patients who underwent surgical treatment between September 2007 and August 2012. We carried out a retrospective review of data from a prospectively maintained database. RESULTS. For slow-flow Type 1 fistulae the ICG videoangiogram demonstrated conclusively that the arteriovenous shunt was obliterated. This is a consideration on the rare occasions where a second fistula is present, an example of which is included in this series. ICG-VA also helps to demonstrate normal vascular anatomy and distinguish these vessels from pathology. For Type II lesions it allowed orientation to the vascular anatomy as demonstrated by the pre-operative angiogram. In one of two cases in this series it ensured to the complete extirpation of a large arteriovenous malformation (AVM). However a second Type II case demonstrated its limitations, as a diffuse intramedullary component could not be identified. Two cases were explored where digital subtraction spinal angiography was not possible and incomplete understanding of the angio-architectures of the lesions were available from Time Resolved dynamic magnetic resonance angiography and/or multi-detector CT angiography. ICG-VA provided invaluable information on alterations in arterio-venous flow that allowed diagnosis and obliteration of the arteriovenous shunts in each case. DISCUSSION. ICG video-angiography is a time-efficient and safe alternative to intra-operative spinal angiography. It provided useful information on haemodynamic changes intraoperatively and completeness of treatment. We discuss its limitations and role in the management of these lesions.

Direct surgery for spinal arteriovenous fistulas of the filum terminale with intraoperative image guidance

STUDY DESIGN

A technical case report of direct surgery for spinal arteriovenous fistulas of the filum terminale.

OBJECTIVE

We present 2 cases of spinal arteriovenous fistulas of the filum terminale directly fed by the anterior spinal artery that were successfully obliterated with intraoperative image guidance such as digital subtraction angiography, intra-arterial dye injection technique, or indocyanine green video angiography.

SUMMARY OF BACKGROUND DATA

The goal of direct surgery for spinal arteriovenous fistulas is the complete obliteration of shunt vessels while preserving the normal circulation of spinal cord. Safe isolation of feeding arteries, nidus, and draining veins needs to be obtained first. Vascular flow or anatomical orientation of shunt vessels also needs to be ensured with intraoperative image guidance.

METHODS

Two cases are presented. The first patient (case 1) had the lesion with a nidus formation at the L2 spinal level supplied directly by the anterior spinal artery via left L1 segmental artery. The second patient (case 2) had a lesion at the L4-L5 spinal level also supplied directly by the anterior spinal artery via the left T11 intercostal artery. Standard exposure of the lesion followed intraoperative image guidance to achieve the appropriate vascular flow or anatomical orientation of the shunt vessels.

RESULTS

Complete obliteration of shunt vessels was successfully achieved without any complications in both cases.

CONCLUSION

Although intraoperative image guidance is certainly not a prerequisite, the concept of safe and minimally invasive surgery makes it indispensable. It can facilitate identification of crucial or important landmarks where anatomic structures may be distorted.

Intraoperative Near-infrared Fluorescence Imaging with Novel Indocyanine Green-Loaded Nanocarrier for Spinal Metastasis: A Preliminary Animal Study

Marginal resection during resection of a spinal metastasis is frequently difficult because of the presence of important tissues such as the aorta, vena cava, and dura mater, including the spinal cord adjacent to the vertebral body. Thus, there is an urgent need for novel intraoperative imaging modalities with the ability to clearly identify bone metastasis. We have proposed a novel nanocarrier loaded with indocyanine green (ICG) (ICG-lactosome) with tumor selectivity attributable to its enhanced permeation and retention (EPR) effect. We studied its feasibility in intraoperative near-infrared (NIR) fluorescence diagnosis with ICG-lactosome for imaging spinal metastasis. A rat model of subcutaneous mammary tumor and a rat model of spinal metastasis of breast cancer were used. Fluorescence emitted by the subcutaneous tumors and the spinal metastasis were clearly detected for at least 24 h. Moreover, imaging of the dissected spine revealed clear fluorescence emitted by the metastatic lesion in the L6 vertebra while the normal bone lacked fluorescence. This study was the first report on NIR fluorescence imaging of spinal metastasis in vivo. NIR fluorescence imaging with ICG-lactosome could be an effective intraoperative imaging modality for detecting spinal metastasis.

Efficacy of indocyanine green videography and real-time evaluation by FLOW 800 in the resection of a spinal cord hemangioblastoma in a child: case report

A 19-month-old child was gradually suffering from gait disturbance and was referred by his pediatrician to the authors' institution. Spinal MRI showed Gd-enhanced spinal cord tumor and congestive myelopathy. Intraoperatively the lesion was seen to be a hemangioblastoma. Because discrimination of the arterialized draining veins from the feeding arteries was difficult, indocyanine green videography was conducted to differentiate them. Real-time evaluation by FLOW 800 revealed that the slope of the average signal intensity in the feeding artery was steeper than that of the arterialized veins. The tumor was successfully resected, and postoperative indocyanine green videography showed total removal of the tumor as a signal-negative region; the circulation time between the feeding artery and the main draining vein was prolonged from 2.5 to 5.5 seconds. Indocyanine green videography and real-time evaluation by FLOW 800 were objective and effective for the excision of a tumor retaining the arteriovenous shunt. The patient recovered from congestive myelopathy and gait disturbance.

Malignancies of the spinal cord

The management of intramedullary spinal cord tumors (IMSCT) is primarily concerned with the preservation of existing neurologic function. To this end, clinical scientists are continually seeking tools and techniques to improve the safety and efficacy of tumor resection and control. Further advances in safety and efficacy can be proposed at each phase of management, from pre-operative screening to post-treatment monitoring. Innovations within the areas of molecular biology and genetics, intraoperative imaging and stereotactic radiosurgery offer exciting new options to explore in the management of IMSCT. This section will review the pathophysiology and epidemiology of IMSCT and the state-of-the-art management before delving into the promising new tools and techniques for each phase of management.

Photodynamic therapy with indocyanine green injection and near-infrared light irradiation has phototoxic effects and delays paralysis in spinal metastasis

OBJECTIVE

The purpose of this study was to investigate the phototoxic effects of photodynamic therapy (PDT) with indocyanine green (ICG) and near-infrared light irradiation on rat mammary adenocarcinoma cells, and its therapeutic efficacy in a rat model of spinal metastasis.

BACKGROUND DATA

Although PDT has been successfully used as a non-radiation treatment for many malignancies, it has not yet been clinically applied for treating spinal metastasis.

METHODS

For the phototoxicity study, CRL-1666 cells were treated with PDT and cell viability was measured by WST-1 assay. For the efficacy study, 26 female Fischer 344 rats with spinal metastasis in the L6 vertebra were divided into three treatment groups: PDT with local injection of ICG (9 rats), PDT with systemic injection of ICG (10 rats), and no treatment or control (7 rats). Both the PDT groups received near-infrared light irradiation with a total energy of 10 J (1 W for 10 sec). The light was delivered directly through a single silica probe which was set on the left side of the L6 vertebral body. Hindlimb motor function was monitored according to the Basso-Beattie-Bresnahan (BBB) scale. Further, the observation periods were calculated to determine the survival time.

RESULTS

The PDT exerted immediate and persistent phototoxic effects. Furthermore, the PDT with local injection of ICG as well as systemic injection of ICG delayed the deterioration of paralysis and prolonged the observation period.

CONCLUSIONS

PDT with ICG injection and near-infrared light irradiation could be an effective local adjuvant treatment for spinal metastasis.