Low Dose ICG for Near-infrared Fluorescence Imaging of Biliary Tract and Tumors
Phase: PHASE2
Conditions: Cholecystitis, Hepatocellular Carcinoma, Liver Metastases
Sponsor: University of Florida

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Low vs Standard Dose Indocyanine Green in the Identification of Biliary Anatomy Using Near-
Infrared Fluorescence Imaging: A Multicenter Randomized Controlled Trial 
 
NCT04942665 
 
12/9/2021 
 
 

 
1. Title: 
• Low dose ICG for near-infrared fluorescence imaging of biliary tract 
2. Investigators: 
 
• Ali Zarrinpar, MD, PhD (PI) 
• Tyler Loftus, MD (co-PI, PI proxy) 
• Alexandra Ladd, MD (co-Investigator) 
• Haley Stone (co-Investigator, medical student) 
• Curtis Warren (Study Coordinator) 
3. Abstract: 
 
We have a series of surgical cases in which we have been able to achieve excellent 
intraoperative biliary visualization with a greatly decreased (50-200X fold lower) dose 
of ICG than the previously published dose. Furthermore, this decreased dose was 
visible in about 15-20 minutes from the time of injection with low liver background 
fluorescence, a significant improvement that would make its utilization in the operating 
room more practical. We hypothesize that a lower dose will allow adequate visualization 
of the extrahepatic biliary tree, including the cystic, common hepatic, and common bile 
ducts. Confirmation of this hypothesis would mean that a lower dose of ICG can be 
administered on the same day of surgery in order to augment real-time intraoperative 
localization of the extrahepatic biliary tree, thereby providing a safe, feasible, and cost-
effective strategy for the surgical treatment of liver disease. 
We intend to test our hypothesis with the following specific aims: 
Aim: To compare the efficacy and utility of a low dose ICG (0.05 mg) protocol with a 
previously published dose (2.5 mg) in imaging the extrahepatic biliary tract. 
 
 

4. Background: 
 
Near-infrared fluorescence (NIRF) imaging after an intravenous injection of indocyanine 
green (ICG) allows for the intraoperative identification of biliary anatomy. ICG binds to 
plasma proteins and emits light with a peak wavelength around 830nm when illuminated 
with near-infrared light. ICG is exclusively excreted by the liver, and biliary excretion 
lasts from several minutes to 24 hours post-injection (1). NIRF imaging has been shown 
to be a safe, easy, fast, cost-effective strategy for delineating biliary anatomy because 
it decreases the risk of bile duct injury and does not require radiation (2)(3)(4). Research 
from our group, among others, has shown that visualization of the extrahepatic biliary 
tract is adequate at a dose on the order of 2.5 mg administered at least 15 minutes prior 
to visualization (5). 
Since the advent of NIRF, imaging technology has improved, with increasing sensitivity 
and improved intraoperative displays. Whether these improvements have resulted in 
increased sensitivity and utility has not yet been demonstrated, nor has the possibility 
of whether improved technology has decreased either the dose required for adequate 
visualization or the time interval prior to optimal visualization. 
5. Specific Aim: 
 
To compare the efficacy and utility of a low dose ICG (0.05 mg) protocol with a 
previously published dose (2.5 mg) in imaging the extrahepatic biliary tract.  
6. Research Plan: 
 
Current standard of care for this service is to administer 2.5 mg of ICG preoperatively 
to patients before surgical bile duct visualization. If there is any further need for 
anatomic information, then a combination of ultrasound and X-ray cholangiography is 
used. For this study, adult patients scheduled to undergo a laparoscopic hepatic or 
biliary operation will be randomized to two groups 1) low dose (0.05 mg) or 2) standard 
dose (2.5 mg) of ICG preoperatively on the day of surgery. Patients with a history of 
adverse reactions or known allergy to ICG, iodine, or iodine dyes will be excluded. 
Pregnant and/or lactating patients will also be excluded. Participants will receive a 
baseline assessment. Demographic information, including age, gender, ethnicity or 
race, body mass index, American Society of Anesthesiologists class, preoperative 
diagnosis, liver function, and complete medical history, will be collected. Case difficulty 
will be graded by the primary surgeon based on standardized 
criteria 
(https://pubmed.ncbi.nlm.nih.gov/29956029/). 
The 
PINPOINT 
Endoscopic 
Fluorescence Imaging System (Stryker Corporation, Kalamazoo, Michigan) will be 
used. This device enables the surgeon to simultaneously see real-time, high-definition 
visible-range and NIR fluorescence videos and to superimpose them. It is currently 
approved by the FDA for intraoperative near-infrared fluorescence imaging. Essentially, 
it is a standard laparoscopic device with an added excitation laser at 805 nm and a filter 
set to allow for visualization of ICG fluorescence. The visualization of the biliary tree will 
be recorded. 

Low 
dose 
or 
standard 
dose 
ICG 
will 
be 
administered by 
the 
anesthesiologist 
as guided by the 
study 
coordinator 
at 
the beginning of 
the case. The 
operating 
surgeon will be 
blinded to the 
dose given. At 
two 
points 
during 
the 
operation 
(1- 
prior 
to 
the 
dissection of the biliary tract and 2- upon completion of the dissection and establishment 
of the critical view of safety), a qualitative assessment will be made by the primary 
surgeon based on the quality of the intraoperative visualization of the extrahepatic 
biliary tree (being able to identify and distinguish the common bile duct, the common 
hepatic duct, and the cystic duct from the surrounding structures and from each other) 
on a scale of 1 to 5 (1 = no improvement/identification not confirmed; 2 = marginally 
improved; 3 = sufficiently improved; 4 = well improved; 5 = greatly improved/exceeds 
expectations). The recorded visualization will also be assessed by a blinded 
independent surgeon who will use the same scale. A quantitative assessment will also 
be performed on the recorded visualization using ImageJ (US National Institutes of 
Health, Bethesda, MD; http://imagej.nih.gov/ij/) by dividing the fluorescence intensity 
signal of the common bile duct by that of the surrounding fat or liver. These quantitative 
measurements will allow an independent measure of duct visualization. Both 
quantitative and qualitative scores will be compared to determine whether there are 
significant differences between the doses. A total of thirty patients (15 in each arm) will 
be required for more than a 90% power to detect a difference in the duct-to-liver ratio 
of 0.2 between the two groups, given an alpha of 0.05 and a standard deviation of 0.15. 
These estimates are based on our previously published results. (5) 
 
 
Patients who are not able to provide informed consent and have a history of sensitivity 
or allergy to shellfish, ICG, or iodine will be excluded from the study. 
 
Randomization: Identical envelopes will be made with a card marked either standard or 
low dose to be chosen in blocks of four. At the time of enrollment, an envelope will be 
selected at random from a box and the subject will be assigned to the corresponding 
arm. This envelope will then be discarded to allow for equal numbers in each group.   
Figure 1. Representative examples of intraoperative images of biliary tract.
GB, gallbladder; L, liver; CHD, common hepatic duct; Cys, cystic duct. 
(Zarrinpar et al, Surgical Innovation 2016)
Example 1
Near-infrared
Superimposed
Conventional
Example 2

 
For the purposes of the study, the recorded videos will be stored on a secure local 
server with access limited only to the study team. This will allow them team to 
perform the image analysis and related calculations. At the end of the study, the 
videos will be deidentified and maintained for possible future research. 
7. Possible Discomforts and Risks: 
 
Using a lower dose of ICG may lead to poorer visualization of the anatomy during 
surgery compared to the standard dose. The surgeons, however, routinely use other 
methods of visualization during surgery (such as ultrasound or x-rays) that would 
decrease the risks of poor visualization during the operation. The most commonly 
reported adverse reactions to ICG are typically mild and included pruritus, shortness 
of breath, and nausea. Less commonly reported events include bronchospasm (a 
condition wherein muscles lining the airways of the lungs constrict or tighten, reducing 
airflow), laryngospasm (a spasm of the vocal cords that temporarily makes it difficult 
to speak or breath), low blood pressure, and cardiac arrest. IVs are routinely used by 
clinicians and they are considered to be low risk. 
8. Possible Benefits: 
Decreasing the dose of ICG may lead to better visualization of the anatomy during 
surgery and also it may decrease the risk of side-effects. 
9. Conflict of Interest: 
 
The investigators have no real or potential conflict of interest with regard to this 
research project. 

10.  Data Safety and Monitoring Plan 
10.1 Data Integrity and Safety Committee 
 
This protocol summary will include a minimum of the following:  
• The UF IRB assigned protocol number, protocol title, PI name, data coordinator 
name or primary study coordinator, regulatory coordinator name, and statistician  
• Date of initial UF IRB approval, date of most recent consent UF IRB 
approval/revision, date of UF IRB expiration, study status, and phase of the study, 
study target accrual and study actual accrual.  
• Protocol objectives with supporting data and list of number of study participants who 
have met each objective.  
• 
Intraoperative measures 
• Summary of toxicities and protocol deviations.  
• Summary of any recent literature which may affect the safety or ethics of the trial.  
 
10.2 Site Monitoring  
 
10.3 Principal Investigator Responsibilities  
As part of the responsibilities assumed by conducting this study, the Principal 
Investigator (PI) agrees to maintain and have available for monitoring adequate case 
records (accurate source documents and CRFs) for the subjects treated under this 
protocol.  
 
The PI will be primarily responsible for monitoring of adverse events, protocol 
violations, and other immediate protocol issues. The study coordinator will collect 
information on subjects enrolled through the use of electronic or paper adverse event 
(AE) forms, CRFs, and Informed Consent forms. 
 
10.4 Interim Analyses & Stopping Rules 
As a phase II feasibility study, our goal is to establish clinical and operative 
expectations around the use of low-dose IV ICG.  Given the standard use of standard 
dose IV ICG, we are not concerned about safety, so a phase I study or safety run-in of 
low dose ICG is not felt to be needed. However, we will monitor and record any AEs 
related to the IV ICG administration in both arms of the study. 
 
Given the published safety data on intraoperative use of ICG, we do not anticipate 
any safety issues between the standard and low dose ICG, but will monitor AEs 
related to ICG administration in real time.  A pre-planned stopping rule for safety is not 
needed. 
 
Given the pilot and feasibility aspects of this study such that a primary efficacy 
difference is not being targeted along with the relatively small numbers of patients and 
short enrollment period, a stopping rule for efficacy is not appropriate. 

11. References 
1.  
Ishizawa T, Tamura S, Masuda K, Aoki T, Hasegawa K, Imamura H, et al. 
Intraoperative fluorescent cholangiography using indocyanine green: a biliary road 
map for safe surgery. J Am Coll Surg. 2009 Jan;208(1):e1–4.  
2.  
Dip F, Roy M, Lo Menzo E, Simpfendorfer C, Szomstein S, Rosenthal RJ. 
Routine use of fluorescent incisionless cholangiography as a new imaging modality 
during laparoscopic cholecystectomy. Surg Endosc. 2015 Jun;29(6):1621–1626.  
3.  
Matsui A, Tanaka E, Choi HS, Winer JH, Kianzad V, Gioux S, et al. Real-time 
intra-operative near-infrared fluorescence identification of the extrahepatic bile ducts 
using clinically available contrast agents. Surgery. 2010 Jul;148(1):87–95.  
4.  
Ishizawa T, Bandai Y, Ijichi M, Kaneko J, Hasegawa K, Kokudo N. Fluorescent 
cholangiography illuminating the biliary tree during laparoscopic cholecystectomy. Br 
J Surg. 2010 Sep;97(9):1369–1377.  
5.  
Zarrinpar A, Dutson EP, Mobley C, Busuttil RW, Lewis CE, Tillou A, et al. 
Intraoperative Laparoscopic Near-Infrared Fluorescence Cholangiography to Facilitate 
Anatomical Identification: When to Give Indocyanine Green and How Much. Surg 
Innov. 2016 Aug;23(4):360–365.  
6.  
Aoki T, Yasuda D, Shimizu Y, Odaira M, Niiya T, Kusano T, et al. Image-
guided liver mapping using fluorescence navigation system with indocyanine green for 
anatomical hepatic resection. World J Surg. 2008 Aug;32(8):1763–1767.  
7.  
Inoue Y, Arita J, Sakamoto T, Ono Y, Takahashi M, Takahashi Y, et al. 
Anatomical Liver Resections Guided by 3-Dimensional Parenchymal Staining Using 
Fusion Indocyanine Green Fluorescence Imaging. Ann Surg. 2015 Jul;262(1):105–
111.  
8.  
Ishizawa T, Fukushima N, Shibahara J, Masuda K, Tamura S, Aoki T, et al. 
Real-time identification of liver cancers by using indocyanine green fluorescent 
imaging. Cancer. 2009 Jun 1;115(11):2491–2504.  
9.  
Kudo H, Ishizawa T, Tani K, Harada N, Ichida A, Shimizu A, et al. Visualization 
of subcapsular hepatic malignancy by indocyanine-green fluorescence imaging during 
laparoscopic hepatectomy. Surg Endosc. 2014 Aug;28(8):2504–2508.  
10.  
Gotoh K, Yamada T, Ishikawa O, Takahashi H, Eguchi H, Yano M, et al. A 
novel image-guided surgery of hepatocellular carcinoma by indocyanine green 
fluorescence imaging navigation. J Surg Oncol. 2009 Jul 1;100(1):75–79.  
11.  
Lim C, Vibert E, Azoulay D, Salloum C, Ishizawa T, Yoshioka R, et al. 
Indocyanine green fluorescence imaging in the surgical management of liver cancers: 
current facts and future implications. J Visc Surg. 2014 Apr;151(2):117–124.  

12.  
Satou S, Ishizawa T, Masuda K, Kaneko J, Aoki T, Sakamoto Y, et al. 
Indocyanine green fluorescent imaging for detecting extrahepatic metastasis of 
hepatocellular carcinoma. J Gastroenterol. 2013 Oct;48(10):1136–1143.  
13.  
van der Vorst JR, Schaafsma BE, Hutteman M, Verbeek FPR, Liefers G-J, 
Hartgrink HH, et al. Near-infrared fluorescence-guided resection of colorectal liver 
metastases. Cancer. 2013 Sep 15;119(18):3411–3418.  
14.  
Qi B, Crawford AJ, Wojtynek NE, Holmes MB, Souchek JJ, Almeida-Porada G, 
et al. Indocyanine green loaded hyaluronan-derived nanoparticles for fluorescence-
enhanced surgical imaging of pancreatic cancer. Nanomedicine. 2018 Jan 
9;14(3):769–780.  
15.  
Imamura H, Sano K, Sugawara Y, Kokudo N, Makuuchi M. Assessment of 
hepatic reserve for indication of hepatic resection: decision tree incorporating 
indocyanine green test.  J Hepatobiliary Pancreat Surg. 2005;12(1):16-22. doi: 
10.1007/s00534-004-0965-9 
16.  
Hope-Ross M, Yannuzzi LA, Gragoudas ES, Guyer DR, Slakter JS, Sorenson 
JA, Krupsky S, Orlock DA, Puliafito CA. Adverse reactions due to indocyanine green. 
Ophthalmology. 1994 Mar;101(3):529-33. doi: 10.1016/s0161-6420(94)31303-0.