Name: measurement of tissue oxygenation using near-infrared spectroscopy in patients undergoing hemodialysis
Uploaded: 2020-10-02T13:00:00
Description: Watch this Scientific Journal Video about Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis at JoVE.com

We thank the dialysis staffs and members of the department of nephrology in Saitama medical center of Jichi Medical University. We would like to thank Editage (www.editage.com) for English language editing.

All participants provided written informed consent. The study was approved by the Institutional Review Board of the Saitama Medical Center, Jichi Medical University, Japan (RIN 15&#8211;104).
1. Device for the monitoring of rSO2
<ol>
	<li>Prepare a NIRS device for measuring tissue oxygenation. This device has four channels and can perform measurement in up to four organs at the same time.</li>
	<li>Prepare a measurement sensor for NIRS monitoring, to evaluate rSO2 value...

<ol>
	<li>Nishiyama, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regional+cerebral+oxygen+saturation+monitoring+for+predicting+interventional+outcomes+in+patients+following+out-of-hospital+cardiac+arrest+of+presumed+cardiac+cause:+A+prospective,+observational,+multicentre+study.">Regional cerebral oxygen saturation monitoring for predicting interventional outcomes in patients following out-of-hospital cardiac arrest of presumed cardiac cause: A prospective, observational, multicentre study.</a> Resuscitation. 96, 135-141 (2015).</li><li>Kobayashi, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+associated+with+a+low+initial+cerebral+oxygen+saturation+value+in+patients+undergoing+cardiac+surgery.">Factors associated with a low initial cerebral oxygen saturation value in patients undergoing cardiac surgery.</a> Journal of Artificial Organs. 20 (2), 110-116 (2017).</li><li>Cruz, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+multimodal+computational+system+using+near-infrared+spectroscopy+predicts+the+need+for+ECMO+initiation+in+neonates+with+congenital+diaphragmatic+hernia.">A novel multimodal computational system using near-infrared spectroscopy predicts the need for ECMO initiation in neonates with congenital diaphragmatic hernia.</a> Journal of Pediatric Surgery. 53 (1), 152-158 (2018).</li><li>MacEwen, C., Sutherland, S., Daly, J., Pugh, C., Tarassenko, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+between+Hypotension+and+Cerebral+Ischemia+during+Hemodialysis.">Relationship between Hypotension and Cerebral Ischemia during Hemodialysis.</a> Journal of the American Socociety of Nephrology. 28 (8), 2511-2520 (2017).</li><li>Polinder-Bos, H. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+cerebral+oxygenation+and+cerebral+blood+flow+during+hemodialysis+-+A+simultaneous+near-infrared+spectroscopy+and+positron+emission+tomography+study.">Changes in cerebral oxygenation and cerebral blood flow during hemodialysis - A simultaneous near-infrared spectroscopy and positron emission tomography study.</a> Journal of Cerebral Blood Flow &amp; Metablism. 40 (2), 328-340 (2020).</li><li>Ookawara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differences+in+tissue+oxygenation+and+changes+in+total+hemoglobin+signal+strength+in+the+brain,+liver,+and+lower-limb+muscle+during+hemodialysis.">Differences in tissue oxygenation and changes in total hemoglobin signal strength in the brain, liver, and lower-limb muscle during hemodialysis.</a> Journal of Artificial Organs. 21 (1), 86-93 (2018).</li><li>Malik, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+ischemia+worsens+during+hemodialysis+in+end-stage+renal+disease+patients.">Tissue ischemia worsens during hemodialysis in end-stage renal disease patients.</a> The Journal of Vascular Access. 18 (1), 47-51 (2017).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+oxygenation+improvement+is+associated+with+hemoglobin+increase+after+hemodialysis+initiation.">Cerebral oxygenation improvement is associated with hemoglobin increase after hemodialysis initiation.</a> TheInternational Journal of Artificial Organs. , (2020).</li><li>Valerianova, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+responsible+for+cerebral+hypoxia+in+hemodialysis+population.">Factors responsible for cerebral hypoxia in hemodialysis population.</a> Physiological Research. 68 (4), 651-658 (2019).</li><li>Ookawara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Associations+of+cerebral+oxygenation+with+hemoglobin+levels+evaluated+by+near-infrared+spectroscopy+in+hemodialysis+patients.">Associations of cerebral oxygenation with hemoglobin levels evaluated by near-infrared spectroscopy in hemodialysis patients.</a> PLoS One. 15 (8), 0236720 (2020).</li><li>Kovarova, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low+Cerebral+Oxygenation+Is+Associated+with+Cognitive+Impairment+in+Chronic+Hemodialysis+Patients.">Low Cerebral Oxygenation Is Associated with Cognitive Impairment in Chronic Hemodialysis Patients.</a> Nephron. 139 (2), 113-119 (2018).</li><li>Miyazawa, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+cerebral+oxygenation+with+estimated+glomerular+filtration+rate+and+cognitive+function+in+chronic+kidney+disease+patients+without+dialysis+therapy.">Association of cerebral oxygenation with estimated glomerular filtration rate and cognitive function in chronic kidney disease patients without dialysis therapy.</a> PLoS One. 13 (6), 0199366 (2018).</li><li>Locatelli, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Haemodialysis+with+on-line+monitoring+equipment:+tools+or+toys.">Haemodialysis with on-line monitoring equipment: tools or toys.</a> Nephrology Dialysis Transplantation. 20 (1), 22-33 (2005).</li><li>Cordtz, J., Olde, B., Solem, K., Ladefoged, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Central+venous+oxygen+saturation+and+thoracic+admittance+during+dialysis:+new+approaches+to+hemodynamic+monitoring.">Central venous oxygen saturation and thoracic admittance during dialysis: new approaches to hemodynamic monitoring.</a> Hemodialysis International. 12 (3), 369-377 (2008).</li><li>Kamijo, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+monitoring+of+blood+pressure+by+analyzing+the+blood+flow+sound+of+arteriovenous+fistula+in+hemodialysis+patients.">Continuous monitoring of blood pressure by analyzing the blood flow sound of arteriovenous fistula in hemodialysis patients.</a> Clinical and Experimental Nephrology. 22 (3), 677-683 (2018).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+cerebral+oxygenation+in+hemodialysis+patients:+cerebral+oxygenation+associates+with+pH,+hemodialysis+duration,+serum+albumin+concentration,+and+diabetes+mellitus.">Factors affecting cerebral oxygenation in hemodialysis patients: cerebral oxygenation associates with pH, hemodialysis duration, serum albumin concentration, and diabetes mellitus.</a> PLoS One. 10 (2), 0117474 (2015).</li><li>Imai, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deterioration+of+Hepatic+Oxygenation+Precedes+an+Onset+of+Intradialytic+Hypotension+with+Little+Change+in+Blood+Volume+during+Hemodialysis.">Deterioration of Hepatic Oxygenation Precedes an Onset of Intradialytic Hypotension with Little Change in Blood Volume during Hemodialysis.</a> Blood Purification. 45 (4), 345-346 (2018).</li><li>Cho, A. R., Kwon, J. Y., Kim, C., Hong, J. M., Kang, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+sensor+location+on+regional+cerebral+oxygen+saturation+measured+by+INVOS+5100+in+on-pump+cardiac+surgery.">Effect of sensor location on regional cerebral oxygen saturation measured by INVOS 5100 in on-pump cardiac surgery.</a> Journal of Anesthesia. 31 (2), 178-184 (2017).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deterioration+of+cerebral+oxygenation+by+aortic+arch+calcification+progression+in+patients+undergoing+hemodialysis:+A+cross-sectional+study.">Deterioration of cerebral oxygenation by aortic arch calcification progression in patients undergoing hemodialysis: A cross-sectional study.</a> BioMed Research International. , 2852514 (2017).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+transfusion+during+haemodialysis+improves+systemic+tissue+oxygenation:+A+case+report.">Blood transfusion during haemodialysis improves systemic tissue oxygenation: A case report.</a> Nefrologia. 37 (4), 435-437 (2017).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+bilateral+lower-limb+muscle+oxygenation+by+low-density+lipoprotein+apheresis+in+a+patient+with+peripheral+artery+disease+undergoing+hemodialysis.">Improvement of bilateral lower-limb muscle oxygenation by low-density lipoprotein apheresis in a patient with peripheral artery disease undergoing hemodialysis.</a> Nefrologia. 39 (1), 90-92 (2019).</li><li>Kitano, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+tissue+oxygenation+in+response+to+sudden+intradialytic+hypotension.">Changes in tissue oxygenation in response to sudden intradialytic hypotension.</a> Journal of Artificial Organs. 23 (2), 187-190 (2020).</li><li>Lemmers, P. M. A., Toet, M. C., van Bel, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+patent+ductus+arteriosus+and+subsequent+therapy+with+indomethacin+on+cerebral+oxygenation+in+preterm+infants.">Impact of patent ductus arteriosus and subsequent therapy with indomethacin on cerebral oxygenation in preterm infants.</a> Pediatrics. 121, 142-147 (2008).</li><li>Ito, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sleep+apnea+syndrome+caused+lowering+of+cerebral+oxygenation+in+a+hemodialysis+patient:+a+case+report+and+literature+review.">Sleep apnea syndrome caused lowering of cerebral oxygenation in a hemodialysis patient: a case report and literature review.</a> Renal Replacement Therapy. 4, 54 (2018).</li><li>Minato, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+monitoring+of+changes+in+cerebral+oxygenation+during+hemodialysis+in+a+patient+with+acute+congestive+heart+failure.">Continuous monitoring of changes in cerebral oxygenation during hemodialysis in a patient with acute congestive heart failure.</a> Journal of Artificial Organs. , (2019).</li></ol>

NIRS monitoring has been mainly used to evaluate cerebral rSO2, especially in cardiovascular or cerebrovascular surgeries, which require extracorporeal circulation. During extracorporeal circulation including HD therapy, some organs could show relative ischemia7,17,18; however, it remains unclear whether tissue oxygenation becomes low or not. Muscle cramps or abdominal pain during HD could be one of the prodromal symp...

Near-infrared spectroscopy (NIRS) has been used to evaluate regional oxygen saturation (rSO2), a marker of tissue oxygenation, especially cerebral oxygenation in various clinical settings1,2,3 and has recently been applied to patients undergoing hemodialysis (HD)4,5,6,7,8,9,10,11. Cerebral rSO2 is reportedly associated with cognitive function in patients undergoing HD or those with non-dialyzed chronic kidney disease (CKD)11,12. However, thus far, the use of NIRS monitoring has been limited in patients with CKD.
As NIRS monitoring is real-time and noninvasive, we assessed its usefulness as a monitoring device in patients undergoing HD. Although NIRS is mainly used to measure cerebral rSO2, we also investigated rSO2 values in other organs during HD. Specifically, the rSO2 measurement sensors were attached to the forehead, the right hypochondrium and the lower legs to evaluate rSO2 in the brain, liver and lower muscles, respectively. The results showed that NIRS monitoring could be a new approach to clarify changes in organ oxygenation during HD or factors affecting tissue oxygenation in CKD patients.
To date, continuous monitoring was performed during HD, blood volume monitoring, central venous oxygen saturation, thoracic admittance and electronic stethoscope-guided estimated blood pressure (BP) in clinical settings13,14,15; however, there are limitations for the prediction of hypotension or the wide use of devices. In contrast, the new noninvasive approach here could provide real-time information on intradialytic oxygen dynamics in individual organs. Therefore, this monitoring method may allow the detection of transient organ ischemia in the early phases of intradialytic hypotension and may also permit the safe performance of HD. This article describes a protocol to measure tissue oxygenation represented by rSO2, as applied in patients undergoing HD.

<table>
	<tbody>
		<tr>
			<td>DBB-100NX</td>
			<td>Nikkiso</td>
			<td>DBB-100NX</td>
			<td>Dialysis machine</td>
		</tr>
		<tr>
			<td>INVOS 5100c</td>
			<td>Covidien Japan</td>
			<td>INVOSTM 5100c</td>
			<td>tissue oxygenation device</td>
		</tr>
		<tr>
			<td>SOMASENSER</td>
			<td>Covidien Japan</td>
			<td>CV-SAFB-SM/INTL</td>
			<td>NIRS sensor</td>
		</tr>
	</tbody>
</table>

measurement of tissue oxygenation using near-infrared spectroscopy in patients undergoing hemodialysis

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in clinical settings including cardiovascular and brain surgery, neonatal monitoring and prehospital medicine. The NIRS monitoring devices are real-time and noninvasive, and have mainly been used for evaluating cerebral oxygenation in critically ill patients during an operation or intensive care. Thus far, the use of NIRS monitoring in patients with chronic kidney disease (CKD) including hemodialysis (HD) has been limited; therefore, we investigated rSO2 values in some organs during HD. We monitored rSO2 values using a NIRS device transmitting near-infrared light at 2 wavelengths of attachment. The HD patients were placed in a supine position, with rSO2 measurement sensors attached to the foreheads, the right hypochondrium and the lower legs to evaluate rSO2 in the brain, liver and lower leg muscles, respectively. NIRS monitoring could be a new approach to clarify changes in organ oxygenation during HD or factors affecting tissue oxygenation in CKD patients. This article describes a protocol to measure tissue oxygenation represented by rSO2 as applied in HD patients.

Cerebral rSO2 values before HD were lower than those in healthy subjects and cerebral rSO2 in HD patients with diabetes mellitus (DM) were lower than those in HD patients without DM (Figure 1)16. Furthermore, although tissue oxygenation continues without a decrease of BP during HD, we incidentally observed changes in cerebral and hepatic rSO2 due to intradialytic hypotension (Figure 2). Due to the continuo...

Watch this Scientific Journal Video about Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis at JoVE.com

Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis

We present a protocol to measure regional oxygen saturation (rSO2) in hemodialysis (HD) patients by using a near-infrared spectroscopy monitor. The rSO2 value is an index of tissue oxygenation. This noninvasive and real-time monitoring could be useful for confirming changes in organ oxygenation during HD.

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in ...

Using this method, we can understand oxygen dynamics of organ during hemodialysis. Prior to the development of this protocol, we could not confirm changes in regional oxygen of each organ. This simple technique can evaluate regional oxygen saturation, non-invasive and in real-time.In dialysis patients, such monitoring might detect intradyalitic hypertension or length ischemia dry during HD.This neuro system has been used in several areas. Cardiovascular and cerebrovascular surgery, neonatal, intensive care, and prehospital emergency. We hope this monitoring will be used in other areas in the future.For example, diagnosis of cognitive impairment. Begin by preparing a near-infrared spectroscopy or NIRS device for measuring tissue oxygenation. This device has four channels and can perform measurement in up to four organs at the same time.In addition, prepare measurement sensors for NIRS monitoring to evaluate regional oxygen saturation values in each organ, by a transmitting near-infrared light at two wavelengths of attachment. Allow the patient to rest in a supine position for at least five minutes before hemodialysis. Then attach measurement sensors to the forehead, the right hypochondrium and lower legs to evaluate regional oxygen saturation in the brain, liver, and lower leg muscles, respectively.For cerebral regional oxygen saturation measurement, attach the sensors to the forehead of the dominant hemisphere. For hepatic measurements, measure the depth of the patient's liver from the body surface, and confirm that this measurement is within 20 to 30 millimeters. Next, attach the measurement sensors to the right hypochondrium.To monitor muscle oxygenation, attach measurement sensors to the right or bilateral lower legs. Connect each sensor to the leads from the device. Then, turn on the device and start measuring oxygenation.Puncture the patient's dialysis shunt to start hemodialysis therapy. Measure blood pressure using a digital blood pressure monitor equipped with the dialysis machine, and collect blood samples using syringes. After starting therapy, start monitoring the tissue oxygenation of the three organs.In addition to the usual monitoring performed during hemodialysis, observe changes in regional oxygen saturation values of each organ and measure blood pressure regularly. Confirm the attachment area and connection between the sensors and leads. Cerebral oxygen saturation values of hemodialysis patients before hemodialysis were lower than those of healthy subjects.The saturation values of hemodialysis patients with diabetes mellitus were lower than those in hemodialysis patients without diabetes. Although tissue oxygenation continues without a decrease of blood pressure during hemodialysis, changes in cerebral and hepatic regional oxygen saturation due to intradyalitic hypotension were observed. When attempting this protocol, it is important to compound the location measurement sensors and to apply the sensors'registry.The new system itself is not a new technique. However, the application of this monitoring system to hemodialysis is another and it is very useful to evaluate changes in organ oxygenation during hemodialysis.

measurement-tissue-oxygenation-using-near-infrared-spectroscopy

Research

JoVE Journal

Medicine

Dual-mode Imaging of Cutaneous Tissue Oxygenation and Vascular Function

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health disorders such as chronic wounds. We report the development of a dual-mode imaging system for non-invasive and non-contact imaging of cutaneous tissue oxygenation and vascular function. The imaging system integrated an infrared camera, a CCD camera, a liquid crystal tunable filter and a high intensity fiber light source. A Labview interface was programmed for equipment control, synchronization, image acquisition, processing, and visualization. Multispectral images captured by the CCD camera were used to reconstruct the tissue oxygenation map. Dynamic thermographic images captured by the infrared camera were used to reconstruct the vascular function map. Cutaneous tissue oxygenation and vascular function images were co-registered through fiduciary markers. The performance characteristics of the dual-mode image system were tested in humans.

A dual-mode imaging system was developed for non-contact assessment of cutaneous tissue oxygenation and vascular function.

Accurate assessment of cutaneous tissue oxygenation and vascular function is important for appropriate detection, staging, and treatment of many health ...

In vivo Near Infrared Fluorescence (NIRF) Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading to an accumulation of lipid-laden intra-luminal plaque, smooth muscle cell proliferation and progressive narrowing of the vessel lumen. The formation of such vulnerable plaques prone to rupture underlies the majority of cases of acute myocardial infarction. The complex molecular and cellular inflammatory cascade is orchestrated by the recruitment of T lymphocytes and macrophages and their paracrine effects on endothelial and smooth muscle cells.1
Molecular imaging in atherosclerosis has evolved into an important clinical and research tool that allows in vivo visualization of inflammation and other biological processes. Several recent examples demonstrate the ability to detect high-risk plaques in patients, and assess the effects of pharmacotherapeutics in atherosclerosis.4 While a number of molecular imaging approaches (in particular MRI and PET) can image biological aspects of large vessels such as the carotid arteries, scant options exist for imaging of coronary arteries.2 The advent of high-resolution optical imaging strategies, in particular near-infrared fluorescence (NIRF), coupled with activatable fluorescent probes, have enhanced sensitivity and led to the development of new intravascular strategies to improve biological imaging of human coronary atherosclerosis.
Near infrared fluorescence (NIRF) molecular imaging utilizes excitation light with a defined band width (650-900 nm) as a source of photons that, when delivered to an optical contrast agent or fluorescent probe, emits fluorescence in the NIR window that can be detected using an appropriate emission filter and a high sensitivity charge-coupled camera. As opposed to visible light, NIR light penetrates deeply into tissue, is markedly less attenuated by endogenous photon absorbers such as hemoglobin, lipid and water, and enables high target-to-background ratios due to reduced autofluorescence in the NIR window. Imaging within the NIR 'window' can substantially improve the potential for in vivo imaging.2,5
Inflammatory cysteine proteases have been well studied using activatable NIRF probes10, and play important roles in atherogenesis. Via degradation of the extracellular matrix, cysteine proteases contribute importantly to the progression and complications of atherosclerosis8. In particular, the cysteine protease, cathepsin B, is highly expressed and colocalizes with macrophages in experimental murine, rabbit, and human atheromata.3,6,7 In addition, cathepsin B activity in plaques can be sensed in vivo utilizing a previously described 1-D intravascular near-infrared fluorescence technology6, in conjunction with an injectable nanosensor agent that consists of a poly-lysine polymer backbone derivatized with multiple NIR fluorochromes (VM110/Prosense750, ex/em 750/780nm, VisEn Medical, Woburn, MA) that results in strong intramolecular quenching at baseline.10 Following targeted enzymatic cleavage by cysteine proteases such as cathepsin B (known to colocalize with plaque macrophages), the fluorochromes separate, resulting in substantial amplification of the NIRF signal. Intravascular detection of NIR fluorescence signal by the utilized novel 2D intravascular NIRF catheter now enables high-resolution, geometrically accurate in vivo detection of cathepsin B activity in inflamed plaque.
In vivo molecular imaging of atherosclerosis using catheter-based 2D NIRF imaging, as opposed to a prior 1-D spectroscopic approach,6 is a novel and promising tool that utilizes augmented protease activity in macrophage-rich plaque to detect vascular inflammation.11,12 The following research protocol describes the use of an intravascular 2-dimensional NIRF catheter to image and characterize plaque structure utilizing key aspects of plaque biology. It is a translatable platform that when integrated with existing clinical imaging technologies including angiography and intravascular ultrasound (IVUS), offers a unique and novel integrated multimodal molecular imaging technique that distinguishes inflammatory atheromata, and allows detection of intravascular NIRF signals in human-sized coronary arteries.

In vivo Near Infrared Fluorescence NIRF Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

We detail a new near-infrared fluorescence (NIRF) catheter for 2-dimensional intravascular molecular imaging of plaque biology in vivo. The NIRF catheter can visualize key biological processes such as inflammation by reporting on the presence of plaque-avid activatable and targeted NIR fluorochromes. The catheter utilizes clinical engineering and power requirements and is targeted for application in human coronary arteries. The following research study describes a multimodal imaging strategy that utilizes a novel in vivo intravascular NIRF catheter to image and quantify inflammatory plaque in proteolytically active inflamed rabbit atheromata.

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading ...

Near Infrared Optical Projection Tomography for Assessments of &beta;-cell Mass Distribution in Diabetes Research

By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen's (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)2; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction2 and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations3. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans.

Near Infrared Optical Projection Tomography for Assessments of &#946;-cell Mass Distribution in Diabetes Research

We describe the adaptation of optical projection tomography (OPT)1 to imaging in the near infrared spectrum, and the implementation of a number of computational tools. These protocols enable assessments of pancreatic &beta;-cell mass (BCM) in larger specimens, increase the multichannel capacity of the technique and increase the quality of OPT data.

By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of ...

Tissue-simulating Phantoms for Assessing Potential Near-infrared Fluorescence Imaging Applications in Breast Cancer Surgery

Inaccuracies in intraoperative tumor localization and evaluation of surgical margin status result in suboptimal outcome of breast-conserving surgery (BCS). Optical imaging, in particular near-infrared fluorescence (NIRF) imaging, might reduce the frequency of positive surgical margins following BCS by providing the surgeon with a tool for pre- and intraoperative tumor localization in real-time. In the current study, the potential of NIRF-guided BCS is evaluated using tissue-simulating breast phantoms for reasons of standardization and training purposes.
Breast phantoms with optical characteristics comparable to those of normal breast tissue were used to simulate breast conserving surgery. Tumor-simulating inclusions containing the fluorescent dye indocyanine green (ICG) were incorporated in the phantoms at predefined locations and imaged for pre- and intraoperative tumor localization, real-time NIRF-guided tumor resection, NIRF-guided evaluation on the extent of surgery, and postoperative assessment of surgical margins. A customized NIRF camera was used as a clinical prototype for imaging purposes.
Breast phantoms containing tumor-simulating inclusions offer a simple, inexpensive, and versatile tool to simulate and evaluate intraoperative tumor imaging. The gelatinous phantoms have elastic properties similar to human tissue and can be cut using conventional surgical instruments. Moreover, the phantoms contain hemoglobin and intralipid for mimicking absorption and scattering of photons, respectively, creating uniform optical properties similar to human breast tissue. The main drawback of NIRF imaging is the limited penetration depth of photons when propagating through tissue, which hinders (noninvasive) imaging of deep-seated tumors with epi-illumination strategies.

Near-infrared fluorescence (NIRF) imaging may improve therapeutic outcome of breast cancer surgery by enabling intraoperative tumor localization and evaluation of surgical margin status. Using tissue-simulating breast phantoms containing fluorescent tumor-simulating inclusions, potential clinical applications of NIRF imaging in breast cancer patients can be assessed for standardization and training purposes.

Inaccuracies in intraoperative tumor localization and evaluation of surgical margin status result in suboptimal outcome of breast-conserving surgery ...

Combined Near-infrared Fluorescent Imaging and Micro-computed Tomography for Directly Visualizing Cerebral Thromboemboli

Direct thrombus imaging visualizes the root cause of thromboembolic infarction. Being able to image thrombus directly allows far better investigation of stroke than relying on indirect measurements, and will be a potent and robust vascular research tool. We use an optical imaging approach that labels thrombi with a molecular imaging thrombus marker&#160;&#8212; a Cy5.5 near-infrared fluorescent (NIRF) probe that is covalently linked to the fibrin strands of the thrombus by the fibrin-crosslinking enzymatic action of activated coagulation factor XIIIa during the process of clot maturation. A micro-computed tomography (microCT)-based approach uses thrombus-seeking gold nanoparticles (AuNPs) functionalized to target the major component of the clot: fibrin. This paper describes a detailed protocol for the combined in vivo microCT and ex vivo NIRF imaging of thromboemboli in a mouse model of embolic stroke. We show that in vivo microCT and fibrin-targeted glycol-chitosan AuNPs (fib-GC-AuNPs) can be used for visualizing both in situ thrombi and cerebral embolic thrombi. We also describe the use of in vivo microCT-based direct thrombus imaging to serially monitor the therapeutic effects of tissue plasminogen activator-mediated thrombolysis. After the last imaging session, we demonstrate by ex vivo NIRF imaging the extent and the distribution of residual thromboemboli in the brain. Finally, we describe quantitative image analyses of microCT and NIRF imaging data. The combined technique of direct thrombus imaging allows two independent methods of thrombus visualization to be compared: the area of thrombus-related fluorescent signal on ex vivo NIRF imaging vs. the volume of hyperdense microCT thrombi in vivo.

This protocol describes the application of combined near-infrared fluorescent (NIRF) imaging and micro-computed tomography (microCT) for visualizing cerebral thromboemboli. This technique allows the quantification of thrombus burden and evolution. The NIRF imaging technique visualizes fluorescently labeled thrombus in excised brain, while the microCT technique visualizes thrombus inside living animals using gold-nanoparticles.

Direct thrombus imaging visualizes the root cause of thromboembolic infarction. Being able to image thrombus directly allows far better investigation of ...

Bioluminescence and Near-infrared Imaging of Optic Neuritis and Brain Inflammation in the EAE Model of Multiple Sclerosis in Mice

Experimental autoimmune encephalomyelitis (EAE) in SJL/J mice is a model for relapsing-remitting multiple sclerosis (RRMS). Clinical EAE scores describing motor function deficits are basic readouts of the immune-mediated inflammation of the spinal cord. However, scores and body weight do not allow for an in vivo assessment of brain inflammation and optic neuritis. The latter is an early and frequent manifestation in about 2/3 of MS patients. Here, we show methods for bioluminescence and near-infrared live imaging to assess EAE evoked optic neuritis, brain inflammation, and blood-brain barrier (BBB) disruption in living mice using an in vivo imaging system. A bioluminescent substrate activated by oxidases primarily showed optic neuritis. The signal was specific and allowed the visualization of medication effects and disease time courses, which paralleled the clinical scores. Pegylated fluorescent nanoparticles that remained within the vasculature for extended periods of time were used to assess the BBB integrity. Near-infrared imaging revealed a BBB leak at the peak of the disease. The signal was the strongest around the eyes. A near-infrared substrate for matrix metalloproteinases was used to assess EAE-evoked inflammation. Auto-fluorescence interfered with the signal, requiring spectral unmixing for quantification. Overall, bioluminescence imaging was a reliable method to assess EAE-associated optic neuritis and medication effects and was superior to the near-infrared techniques in terms of signal specificity, robustness, ease of quantification, and cost.

We show a technique for in vivo live bioluminescence and near-infrared imaging of optic neuritis and encephalitis in the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis in SJL/J mice.

Experimental autoimmune encephalomyelitis (EAE) in SJL/J mice is a model for relapsing-remitting multiple sclerosis (RRMS). Clinical EAE scores describing ...

A Quantitative Sensory Testing Paradigm to Obtain Measures of Pain Processing in Patients Undergoing Breast Cancer Surgery

Chronic pain following surgery, persistent postsurgical pain, is an important highly prevalent condition contributing to significant symptom burden and lower quality of life. Persistent postsurgical pain is relatively refractory to treatment hence generating a high need for preventive strategies and treatments. Therefore, the identification of patients at risk of developing persistent pain is an area of active ongoing research. Recently it was demonstrated that peri-operative disruptions in central pain processing may be able to predict persistent postsurgical pain at long term follow-up in breast cancer patients. The aim of the current report is to present a short protocol to obtain pain thresholds to different stimuli at multiple sites and a measure of endogenous analgesia in breast cancer patients. We have used this method successfully in a clinical context and detail some representative results from a clinical study.

Persistent postsurgical pain may be related to changes in pain processing. By assessing pain in response to standardized stimuli, changes in pain processing can be elucidated. We present methods to obtain pain thresholds to different stimuli and a measure of endogenous analgesia in patients undergoing breast cancer surgery.

Chronic pain following surgery, persistent postsurgical pain, is an important highly prevalent condition contributing to significant symptom burden and ...

Skeletal Muscle Neurovascular Coupling, Oxidative Capacity, and Microvascular Function with 'One Stop Shop' Near-infrared Spectroscopy

Exercise represents a major hemodynamic stress that demands a highly coordinated neurovascular response in order to match oxygen delivery to metabolic demand. Reactive hyperemia (in response to a brief period of tissue ischemia) is an independent predictor of cardiovascular events and provides important insight into vascular health and vasodilatory capacity. Skeletal muscle oxidative capacity is equally important in health and disease, as it determines the energy supply for myocellular processes. Here, we describe a simple, non-invasive approach using near-infrared spectroscopy to assess each of these major clinical endpoints (reactive hyperemia, neurovascular coupling, and muscle oxidative capacity) during a single clinic or laboratory visit. Unlike Doppler ultrasound, magnetic resonance images/spectroscopy, or invasive catheter-based flow measurements or muscle biopsies, our approach is less operator-dependent, low-cost, and completely non-invasive. Representative data from our lab taken together with summary data from previously published literature illustrate the utility of each of these end-points. Once this technique is mastered, application to clinical populations will provide important mechanistic insight into exercise intolerance and cardiovascular dysfunction.

Here, we describe a simple, non-invasive approach using near-infrared spectroscopy to assess reactive hyperemia, neurovascular coupling and skeletal muscle oxidative capacity in a single clinic or laboratory visit.

Exercise represents a major hemodynamic stress that demands a highly coordinated neurovascular response in order to match oxygen delivery to metabolic ...

A New Best Practice for Validating Tail Vein Injections in Rat with Near-infrared-Labeled Agents

Intravenous (IV) administration of agents into the tail vein of rats can be both difficult and inconsistent. Optimizing tail vein injections is a key part of many experimental procedures where reagents need to be introduced directly into the bloodstream. Unwittingly, the injection can be subcutaneous, possibly altering the scientific outcomes. Utilizing a nanoemulsion-based biological probe with an incorporated near-infrared fluorescent (NIRF) dye, this method offers the capability of imaging a successful tail vein injection in vivo. With the use of a NIRF imager, images are taken before and after the injection of the agent. An acceptable IV injection is then qualitatively or quantitatively determined based on the intensity of the NIRF signal at the site of injection.

Here we present a method to validate tail vein injections in rats by utilizing near-infrared fluorescence imaging data from dyes incorporated into agents or biological probes. The tail is imaged before and after the injection, the fluorescent signal is quantified, and an assessment of the injection quality is made.

Intravenous (IV) administration of agents into the tail vein of rats can be both difficult and inconsistent. Optimizing tail vein injections is a key part ...

How to Administer Near-Infrared Spectroscopy in Critically ill Neonates, Infants, and Children

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated hemoglobin molecules. A probe placed on the skin emits light that is absorbed, scattered, and reflected by the underlying tissue. Detectors in the probe sense the amount of reflected light: this reflects the organ-specific ratio of oxygen supply and consumption - independent of pulsatile flow. Modern devices enable the simultaneous monitoring at different body sites. A rise or dip in the rSO2 curve visualizes changes in oxygen supply or demand before vital signs indicate them. The evolution of rSO2 values in relation to the starting point is more important for interpretation than are absolute values.
A routine clinical application of NIRS is the surveillance of somatic and cerebral oxygenation during and after cardiac surgery. It is also administered in preterm infants at risk for necrotizing enterocolitis, newborns with hypoxic ischemic encephalopathy and a potential risk of impaired tissue oxygenation. In the future, NIRS could be increasingly used in multimodal neuromonitoring, or applied to monitor patients with other conditions (e.g., after resuscitation or traumatic brain injury).

This protocol is designed to assist clinicians to measure regional tissue oxygenation at different body sites in infants and children. It can be used in situations where tissue oxygenation is potentially compromised, particularly during cardiopulmonary bypass, when using non-pulsatile cardiac-assist devices, and in critically ill neonates, infants and children.

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated ...