Clinical characteristics and analysis of vestibular-evoked myogenic potentials in patients with sudden sensorineural hearing loss in different ages.

BACKGROUND: Numerous studies have found that patients experiencing sudden sensorineural hearing loss (SSHL), with or without accompanying vertigo, often show impaired vestibular function. However, there is a dearth of studies analyzing vestibular-evoked myogenic potentials (VEMPs) in SSHL patients across various age groups. AIM: To investigate vestibular condition in SSHL patients across various age demographics. METHODS: Clinical data of 84 SSHL patients were investigated retrospectively. Audiometry, cervical vestibular evoked myogenic potentials (c-VEMPs), and ocular vestibular evoked myogenic potentials (o-VEMPs) were conducted on these patients. Parameters assessed included the latencies of P1 and N1 waves, as well as the amplitudes of P1-N1 waves. Moreover, the study evaluated the influence of factors such as sex, affected side, configuration of hearing loss, and presence of accompanying vertigo. RESULTS: Among the 84 SSHL patients, no significant differences were observed among the three groups in terms of gender, affected side, and the presence or absence of vertigo. Group II (aged 41-60 years) had the highest number of SSHL cases. The rates of absent o-VEMPs in the affected ears were 20.83%, 31.58%, and 22.72% for the three age groups, respectively, with no statistically significant difference among them. The rates of absent c-VEMPs in the affected ears were 8.3%, 34.21%, and 18.18% for the three age groups, respectively, with significant differences. In the unaffected ears, there were differences observed in the extraction rates of o-VEMPs in the unaffected ears among the age groups. In the three age groups, no significant differences were noted in the three age groups in the latencies of P1 and N1 waves or in the amplitude of N1-P1 waves for c-VEMPs and o-VEMPs, either on the affected side or on the unaffected side, across the three age groups. CONCLUSION: The extraction rate of VEMPs is more valuable than parameters. Regardless of the presence of vertigo, vestibular organs are involved in SSHL. Notably, SSHL patients aged 41-60 appear more susceptible to damage to the inferior vestibular nerve and saccule.

Oropharyngeal Stenosis Caused by Significant Scar Hyperplasia Following Tonsillectomy: A Case Report.

Oropharyngeal stenosis (OPS) is a relatively rare long-term complication of tonsillectomy in children, resulting from the narrowing of the upper aerodigestive tract between the soft palate, pharyngeal sidewalls, and base of the tongue. This is the first reported case of OPS due to significant scar hyperplasia; however, whether it is as prone to recurrence as skin scar hypertrophy remains unknown. In this article, we present the case of a 5-year-old girl who presented to our otolaryngology clinic with sleep snoring and suffocation. Her medical history included tonsillectomy and adenoidectomy, performed 3 years prior to presentation. The patient underwent a combination of surgery and administration of triamcinolone injections, resulting in significant symptomatic improvement. To date, no signs of recurrence have been reported.

Polarization-Insensitive Metasurface Cloak for Dynamic Illusions with an Electromagnetic Transparent Window.

Artificial camouflage has garnered long-standing interest in both academia and industry. The metasurface-based cloak has attracted much attention due to the powerful capability of manipulating the electromagnetic wave, convenient multifunctional integration design, and easy fabrication. However, existing metasurface-based cloaks tend to be passive and of single function and monopolarization, which cannot meet the requirement of applications in ever-changing environments. So far, it is still challenging to realize a reconfigurable full-polarization metasurface cloak with multifunctional integration. Herein, we proposed an innovative metasurface cloak, which can simultaneously realize dynamic illusion effects at lower frequencies (e.g., 4.35 GHz) and specific microwave transparency at higher frequencies (e.g., X band) for communication with the outside environment. These electromagnetic functionalities are demonstrated by both numerical simulations and experimental measurements. The simulation and measurement results agree well with each other, indicating that our metasurface cloak can generate various electromagnetic illusions for full polarizations as well as a polarization-insensitive transparent window for the signal transmission to enable the communication between the cloaked device and the outside environment. It is believed that our design can offer powerful camouflage tactics to address the stealth problem in ever-changing environments.

Benign paroxysmal positional vertigo with congenital nystagmus: A case report.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is a form of temporary vertigo induced by moving the head to a specific position. It is a self-limited, peripheral, vestibular disease and can be divided into primary and secondary forms. Congenital nystagmus (CN), an involuntary, rhythmic, binocular-symmetry, conjugated eye movement, is found at birth or within 3 mo of birth. According to the pathogenesis, CN can be divided into sensory-defect nystagmus and motor-defect nystagmus. The coexistence of BPPV and CN is rarely seen in the clinic. CASE SUMMARY: A 62-year-old woman presented to our clinic complaining of a 15-d history of recurrent positional vertigo. The vertigo lasting less than 1 min occurred when she turned over, sometimes accompanied by nausea and vomiting. Both the patient and her father had CN. Her spontaneous nystagmus was horizontal to right; however, the gaze test revealed variable horizontal nystagmus with the same degree when the eyes moved. The patient's Dix-Hallpike test was normal, except for persistent nystagmus, and the roll test showed severe variable horizontal nystagmus, which lasted for about 20 s in the same direction as her head movement to the right and left, although the right-side nystagmus was stronger than the left-side. Since these symptoms were accompanied by nausea, she was diagnosed with BPPV with CN and treated by manual reduction. CONCLUSION: Though rare, if BPPV with CN is correctly identified and diagnosed, reduction treatment is comparably effective to other vertigo types.

A Dynamic Thermal Camouflage Metadevice with Microwave Scattering Reduction.

With rapid development of radar and infrared (IR) surveillance technologies, the need for microwave-IR compatible camouflage is now more than ever. Here, a novel multispectral metadevice is proposed to simultaneously achieve microwave scattering reduction, dynamic IR camouflage, and low IR reflection. This metadevice is constructed by the coding thermoelectric elements with the properly designed phase arrangement, and the incident microwave energy can be redirected to the nonthreatening directions for specular reflection reduction. The dynamic IR camouflage with low IR reflection is realized by using the thermoelectric cooling and heating effect and high-IR-absorptivity surface. The above three functionalities are demonstrated by experimental measurement. The 10 dB scattering reduction can be realized at the microwave band of 10-16.1 GHz. In the IR region, the designed metadevice can not only dynamically modulate the surface temperature for matching different background temperatures, but also realize the pixel temperature control for adapting to a spatially varying thermal background. In addition, it reflects almost no surrounding thermal signals compared with the traditional low-emissivity IR stealth material. This study paves an effective way to achieve microwave-IR compatible camouflage, which may inspire the future researches and applications in multispectral camouflage and stealth fields.

Long-Term Outcomes of Patients with Self-Expandable Transcatheter Heart Valve Embolized in the Aorta.

This study assesses the long-term outcomes of patients who suffered from self-expandable transcatheter heart valve (THV) embolized in the aorta in transcatheter aortic valve implantation (TAVI).We retrospectively reviewed the patients with self-expandable THV embolized in the aorta. Follow-up computed tomography was performed to assess the THV migration, struct fractures, and device-related aortic complications.Of the 539 TAVI patients, 11 suffered from self-expandable THV embolized in the aorta. Two patients underwent open-heart surgery to remove the embolized THVs in the ascending aorta. Embolized THVs were repositioned in the aortic arch distal to the left subclavian artery (n = 3) and the thoracic descending aorta (n = 6). Three patients died during a median follow-up time of 40 months. The remaining eight survivors presented with New York Heart Association functional class I or II at the last follow-up. Degeneration of embolized prostheses with thick leaflets and rolled cusp edges was observed in three patients. There was no evidence of valve migration, strut fracture, prosthesis-associated aortic complication, and thrombosis attached on embolized valve for all patients with THVs repositioned in the aorta.Self-expandable THV embolization can be effectively managed in TAVI. Although some embolized valves exhibited leaflet degeneration, the long-term safety of repositioning embolized self-expandable THV in the aorta is assured.

Vessel structural stress mediates aortic media degeneration in bicuspid aortopathy: New insights based on patient-specific fluid-structure interaction analysis.

This study aimed to assess the relationship between local mechanical stimuli and regional aortic tissue degeneration using fluid-structure interaction (FSI) analysis in patients with bicuspid aortic valve (BAV) disease. Nine patients underwent ascending aortic replacement were recruited. Tissues were collected to evaluate the pathology features in four regions, greater curvature (GC-region), posterior (P-region), anterior (A-region), and lesser curvature (LC-region). FSI analysis was performed to quantify vessel structural stress (VSS) and flow-induced parameters, including wall shear stress (WSS), oscillatory shear index (OSI), and particle relative residence time (RRT). The correlation between these biomechanical metrics and tissue degeneration was analyzed. Elastin in the medial layer and media thickness were thinnest and the gap between fibers was biggest in the GC-region, followed by the P-region and A-region, while the elastin and media thickness were thickest and the gap smallest in the LC-region. The collagen deposition followed a pattern with the biggest in the GC-region and least in the LC-region. There is a strong negative correlation between mean or peak VSS and elastin thickness in the arterial wall in the GC-region (r = -0.917; p = 0.001 and r = -0.899; p = 0.001), A-region (r = -0.748; p = 0.020 and r = -0.700; p = 0.036) and P-region (r = -0.773; p = 0.014 and r = -0.769; p = 0.015), and between mean VSS and fiber distance in the A-region (r = -0.702, p = 0.035). Moreover, strong negative correlation between mean or peak VSS and media thickness was also observed. No correlation was found between WSS, OSI, and RRT and aortic tissue degeneration in these four regions. These findings indicate that increased VSS correlated with local elastin degradation and aortic media degeneration, implying that it could be a potential biomechanical parameter for a refined risk stratification for patients with BAV.

Surgical Interventions Are Effective for Treating Unruptured Sinus of Valsalva Aneurysms.

Background: This study investigates the optimal management for unruptured sinus of Valsalva aneurysms (USVAs) combined with other cardiovascular lesions. Methods: This retrospective study examined 33 USVA patients who underwent surgical repair from February 1, 2007 to January 31, 2012. We analyzed the surgical procedures and the patients' quality of life after surgery. Additionally, echocardiography follow-up was performed before and after the operation. Results: Most USVAs (87.8%) originated in the right coronary sinus. Aside from one patient who was preoperatively misdiagnosed as having a ruptured sinus of Valsalva aneurysm (SVA). USVAs of the right coronary sinus were addressed by reinforcing this sinus with a Dacron patch through the right ventricle. USVAs were corrected by aortotomy using an autogenous pericardium patch when they originated in the non-coronary or left coronary sinus. Thirty patients (90.9%) were followed up for 22-119 months. No early death, residual fistula or SVA recurrence were found during the follow-up period. They all had a good quality of life and good heart function (New York Heart Association class I-II). Conclusions: Active surgical repair of an USVA can be achieved with satisfactory results in patients combined with other cardiovascular lesions.

Short-term assessment of radial artery grafts with multidetector computed tomography.

BACKGROUND: The clinical use of the radial artery (RA) in coronary artery bypass grafting (CABG) is still limited worldwide, although it has been recommended by several guidelines. Multidetector computed tomography (MDCT) is widely used to evaluate graft patency, as invasive coronary angiography could cause potentially serious risks including bleeding, dissection and stroke. This study aims to report the short-term results of the RA in CABG with MDCT. METHODS: The study population consists of 41 consecutive patients undergoing elective CABG with the RA graft between 2017 to 2018, with MDCT performed to evaluate graft patency during follow-up, and target vessels for the RA were non-left anterior descending coronary arteries with > 70% stenosis. RESULTS: A total of 150 grafts were assessed by MDCT during follow-up (mean, 8.9 ± 5.1 months). MDCT could clearly show the structure and patency of grafts, even for complex coronary artery revascularization. Graft patency of the left internal mammary artery was 92.9% (39/42), with the RA patency of 84.4% (38/45) and the patency of the saphenous vein graft of 81.1% (30/37). And the RA anastomosed to the left coronary artery system might have better patency than the RA anastomosed to the right coronary artery system (25/29, 86.2% vs 13/16, 81.3%, p = 0.686). CONCLUSIONS: The short-term patency rate of RA grafts is good, and the RA might be associated with better patency when anastomosed to the left but not the right coronary artery. MDCT could provide excellent visualization of grafts in CABG.

Short- and Long-Term Outcome after Emergent Cardiac Surgery during Transcatheter Aortic Valve Implantation.

OBJECTIVE: Our study aimed to evaluate short- and long-term outcomes of patients who required emergent conversion from transcatheter aortic valve implantation (TAVI) to open surgery. Besides, the reasons and procedural settings of emergent cardiac surgery (ECS) were also reported. METHODS: We retrospectively reviewed the patients who underwent TAVI in our institution between 2012 and 2019 and collected the clinical data of cases who converted from TAVI to bail-out surgery. Telephone and outpatient follow-ups were performed. RESULTS: Of 516 TAVI patients, 20 required ECS, and the bail-out surgery occurred less frequently with the increase in TAVI volume. The most common reason for conversion was left ventricular perforation (7/20, 35.0%). Thirty-day mortality was 35.0% in ECS patients. Kaplan-Meier survival curves showed that the cumulative survival rate was 65.0% at 1 year, 50.1% at 5 years in all ECS patients, and 77.1% at 5 years in patients who survived over 30 days after conversion. CONCLUSION: Although the bail-out operation was performed immediately after TAVI abortion, ECS still associated with high 30-day mortality. The long-term survival benefit was seen in patients surviving from bail-out surgery. An experienced TAVI team is of crucial importance in avoiding ECS-related life-threatening complications and providing effective salvage surgery.

Application of the descending branch of the lateral circumflex femoral artery in coronary artery bypass grafting.

OBJECTIVE: To investigate a technical method for harvesting and using the descending branch of the lateral circumflex femoral artery (DLCFA) in coronary artery bypass grafting (CABG). METHODS: Between January 2017 and January 2019, 40 patients (36 in the planed selection group and 4 in the temporary decision group) with mean age of 49.1 ± 7.5 years received DLCFA as an arterial conduit in CABG. In all patients, the DLCFA was successfully harvested via an anterior thigh incision. Depending on the location of the target vessel, the DLCFA was used as a free graft or a composite graft. RESULTS: Of the 44 patients in the planned selection group, DLCFA harvesting was abandoned in 8 patients because computed tomographic angiography revealed anatomical variation or stenosis of the superficial femoral artery. Of the 5 patients in the temporary decision group, harvesting was abandoned in 1 because of short length and thin caliber. On an average, 3.7 ± 0.9 distal anastomoses were created during CABG, with no adverse effects. The length of the harvested DLCFA was 9.9 ± 1.7 cm, with an average proximal lumen diameter of 3.4 ± 0.7 mm. The DLCFA was used as a free graft in 26 patients and as a "Y"-shape composite graft in 14 patients. Total arterial CABG was performed in 75% of the patients. CONCLUSIONS: The DLCFA is an alternative conduit for CABG. It can be harvested easily and safely. However, preoperative computed tomographic angiography examination is necessary for the smooth application of the DLCFA, and an appropriate strategy for graft establishment should be considered.

Comparison of Procedural and 1-Year Clinical Results of Transcatheter Aortic Valve Implantation Using Prostheses with Different Design of Support Frame.

Our study aimed to investigate whether the frame design of transcatheter heart valve (THV) affects the procedural and clinical results of transcatheter aortic valve implantation (TAVI).We retrospectively reviewed 163 patients with aortic stenosis who underwent TAVI using different types of THV (Edwards SAPIEN, n = 31; Venus-A, n = 63; and J-Valve, n = 69). The procedural outcomes and follow-up results for 1-year were compared among groups.The patients who underwent TAVI using J-Valve had a higher mean transaortic pressure gradient than those using SAPIEN or Venus-A after TAVI (1-year follow-up; P = 0.017, P < 0.001, respectively), whereas no difference was observed between the patients with SAPIEN and Venus-A prosthesis (P = 0.150). The incidence of permanent pacemaker implantation was highest in patients with Venus-A (19.0%), followed by SAPIEN (9.7%), and lowest in J-Valve (4.3%) (P = 0.025). No difference was observed in the 30-day mortality rate among the groups (P = 1.000). Moreover, Kaplan-Meier survival analysis revealed that there was no significant difference in the 1-year cumulative patient survival rate among three patient cohorts (log-rank, P = 0.850).The frame design of THVs could affect the valve-related hemodynamics and the incidence of permanent pacemaker implantation in TAVI, whereas it did not influence the survival rate of TAVI patients during 1-year follow-up period. All three THVs provided a convincing short-term outcome for TAVI patients.

Structural Valve Deterioration after Transcatheter Aortic Valve Implantation Using J-Valve: A Long-Term Follow-Up.

PURPOSE: Our study aimed to investigate the structural valve deterioration (SVD) after transcatheter aortic valve implantation (TAVI) using J-Valve. METHODS: In all, 14 patients with aortic stenosis (AS) and 4 patients with pure aortic regurgitation (PAR) were available in the study. Four-year follow-up was performed in all patients, and the clinical data and echocardiographic findings were recorded and analyzed. RESULTS: All patients survived at the 4-year follow-up. There was no evidence of morphological SVD or prosthetic valve thrombosis in enrolled patients. None of the hemodynamic SVD occurred in patients with PAR. Mean gradients decreased from 61.93 ± 15.42 mm Hg (pre-TAVI) to 19.64 ± 9.16 mm Hg (discharge) in patients with AS (p <0.001); subsequently, a slight increase was observed in the mean trans-aortic gradient throughout follow-up (p = 0.967). Overall, in patients with AS, six individuals suffered moderate (3/14, 21.4%) or severe (3/14, 21.4%) hemodynamic SVD at 4-year follow-up. CONCLUSIONS: The limited number of cases provides a preliminary indication of the long-term efficacy of TAVI using J-Valve in patients with PAR. In patients with AS, although the higher rate of SVD was observed, the overall transcatheter heart valve (THV) hemodynamics remained stable over time after prosthetic valve implantation and the long-term durability of J-Valve was convincing.

The Etiological Heterogeneity of Bicuspid Aortopathy between Ascending and Root Morphotype.

BACKGROUND: Valve-related hemodynamics and intrinsically regulated matrix proteases are 2 determined pathogenetic factors associated with medial elastin degeneration in bicuspid aortopathy. This study analyzed the association between elastic fiber deterioration and the 2 pathogenetic factors in ascending and root morphotypes, aiming to elucidate the etiological heterogeneity between the 2 morphotypes. METHODS: Four-dimensional flow cardiac magnetic resonance was used to measure the regional wall shear stress (WSS) on the ascending aorta, and matrix metalloproteinase (MMP) expression was assessed by immunoblotting. After histopathology analysis of aortic tissue, we assessed whether elevated regional WSS and increased MMP expression corresponded with medial elastin thinning. RESULTS: Increased regional WSS corresponded with medial elastin thinning in both morphotypes. Increased expression of different MMP isoforms corresponded with medial elastin degeneration in bicuspid aortopathy. The significantly increased expression of MMP-2 corresponded with a decrease of elastic fiber thickness in the ascending morphotype (P = .046), whereas elastic fiber thinning was associated with high levels of MMP-3 expression (P = .012) in the root morphotype. No association was observed between regional WSS and MMP expression. CONCLUSION: There is no difference in the effect of valve-related hemodynamics between ascending and root morphotype, and MMPs are not involved in the process of elastic fiber degeneration induced by increased WSS. The increased expression of different MMP isoforms was observed in the context of elastic fiber degeneration between the 2 morphotypes, implying that heterogeneity between them is revealed in the different intrinsic pathway of medial elastin degradation.

The Heterogeneous Phenotype of Bicuspid Aortopathy Attribute to Different Dominant Pathogenesis.

PURPOSE: Our study aimed to investigate the potential pathogenetic theories of different phenotype prevalence in bicuspid aortopathy. METHODS: A total of 407 bicuspid aortic valve (BAV) patients with aortic dilation were retrospectively reviewed. Association was determined between aortic valve lesion types and aortic configurations to confirm the homogeneous BAV subsets, and then, dominance analysis was used to evaluate the relative importance of two components of aortic valve lesion (BAV phenotype and valvular dysfunction) that associated with aortic configurations in each subgroup. RESULTS: Dominance analysis showed that Type-1 LR was the dominant contributor (79.0% and 79.6%) associated with the higher prevalence of the dilation of aortic root (AoR) and ascending aorta (AAo) in BAV patients with Type-1 LR and aortic regurgitation (AR) or aortic stenosis (AS) + AR. However, AS was the main contributor (60.0%) associated with the raised incidence of the dilation of AAo and proximal aortic arch (PArc) in Type-0 LAT and AS. CONCLUSIONS: Different dominant pathogenetic theory determined the phenotype of BAV aortopathy. In patients of Type-1 LR with AR, inherent disposition is mainly responsible for the higher frequency of AoR dilation. Valve-related hemodynamics determined greater prevalence of the dilation of AAo and PArc in patients of Type-0 LAT with AS.

Intraluminal thrombus attached to the lesser curvature of the aortic arch and cerebral ischemic stroke after its surgical removal.

Some cases of thrombi at the ascending and descending aorta have been reported, but there are only a few reports of intraluminal aortic arch thrombi. Most intraluminal thrombi are associated with atherosclerotic lesions at the aortic wall. Here, we report a case of an intraluminal thrombus attached to the lesser curvature of the aortic arch. The thrombus was successfully and completely excised, and the pathologic study suggested no obvious atherosclerotic changes in the aortic wall. Two months after surgical removal of the thrombus, the patient suffered a severe cerebral ischemic stroke caused by a newly formed thromboembolism in the innominate artery.

Development of a macromolecular dual-modality MR-optical imaging for sentinel lymph node mapping.

OBJECTIVE: To evaluate the effectiveness of a dual magnetic resonance-near infrared fluorescence optical imaging agent, poly(l-glutamic acid)-DTPA-Gd-NIR813, for both preoperative and intraoperative visualization and characterization of sentinel lymph nodes (SLN) in mice. MATERIALS AND METHODS: Poly(L-glutamic acid) was conjugated with DTPA-Gd and NIR813 dye to obtain PG-DTPA-Gd-NIR813. To confirm drainage into the SLNs, this agent was injected subcutaneously into the front paw of nude mice followed by isosulfan blue (n = 6). Furthermore, PG-DTPA-Gd-NIR813 was injected subcutaneously at doses of 0.002 mmol Gd/kg (4.8 nmol eq. NIR813) and 0.02 mmol Gd/kg (48 nmol eq. NIR813) (n = 3/dose). To differentiate metastatic from nonmetastatic lymph nodes, nude mice bearing human oral squamous cell carcinoma (DM14) were injected intralingually with 0.02 mmol Gd/kg PG-DTPA-Gd-NIR813 (n = 3). Pre- and postcontrast images were taken using 4.7 T Bruker MRI scanner and Xenogen optical imaging system. The status of lymph nodes resected under the guidance of optical imaging was confirmed by histologic examinations. RESULTS: PG-DTPA-Gd-NIR813 colocalized with isosulfan blue, indicating drainage to the SLN. After subcutaneous injection, axiliary and branchial lymph nodes were clearly visualized with both T1-weighted MR and optical imaging within 3 minutes of contrast injection, even at the lowest dose tested (0.002 mmol Gd/kg). After intralingual injection in tumor-bearing mice, MR imaging identified 4 of the 6 superficial cervical lymph nodes, whereas near-infrared fluorescence (NIRF) optical imaging identified all 6 cervical nodes. The pattern of contrast enhancement of SLN visualized in MR images showed a characteristic ring-shaped appearance with a central filling defect, possibly resulting from nodal infiltration of metastatic lesions. Histopathologic examination of the SLNs resected under NIRF imaging guidance revealed micrometastases in all 6 SLNs identified by NIRF imaging. CONCLUSIONS: The dual modality imaging method demonstrated in this study represents an effective technique for localization and characterization of SLN.

A novel method for imaging in vivo degradation of poly(L-glutamic acid), a biodegradable drug carrier.

PURPOSE: To develop an L-PG-based imaging probe suitable for assessing the degradation of L-PG in vivo. MATERIALS AND METHODS: Conjugates of L-PG and a near-infrared fluorescence (NIRF) dye, NIR813, were characterized with regard to quenching efficiency and degradability by cathepsin B (CB) and other proteases. The kinetics of L-PG-NIR813's degradation and its degradation in orthotopic human U87/TGL glioma in nude mice after intravenous injection was assessed using NIRF optical imaging (n = 3). RESULTS: The fluorescence signal from L-PG-NIR813 was efficiently quenched and activated at NIR813 loadings of 8-10%. Upon exposure to CB, the fluorescence intensity of L-PG-NIR813 increased 10-fold. L-PG-NIR813 was also degraded by another cysteine protease cathepsin L, but not by MMP-2, cathepsin E, cathepsin D, and plasmin. A selective CB inhibitor blocked the fluorescence activation. After intravenous injection, the degradation of L-PG-NIR813 was visualized primarily in the liver, which peaked at 4 h postinjection. Activation of L-PG-NIR813 but not D-PG-NIR813 was clearly seen in U87/TGL tumors. CONCLUSION: Our results indicate that L-PG-NIR813 may be used to monitor the in vivo degradation of L-PG-based polymeric drugs, and that this agent may prove useful in noninvasive imaging of protease activity, particularly that of cysteine proteases.