Pilot-phase PET/CT study targeting integrin αvβ6 in pancreatic cancer patients using the cystine-knot peptide-based 18F-FP-R01-MG-F2

PURPOSE

A novel cystine-knot peptide-based PET radiopharmaceutical, 18F-FP-R01-MG-F2 (knottin), was developed to selectively bind to human integrin αvβ6 which is overexpressed in pancreatic cancer. The purpose of this study is to evaluate the safety, biodistribution, dosimetry, and lesion uptake of 18F-FP-R01-MG-F2 in patients with pancreatic cancer.

METHODS

Fifteen patients (6 men, 9 women) with histologically confirmed pancreatic cancer were prospectively enrolled and underwent knottin PET/CT between March 2017 and February 2021 (ClinicalTrials.gov Identifier NCT02683824). Vital signs and laboratory results were collected before and after the imaging scans. Maximum standardized uptake values (SUVmax) and mean SUV (SUVmean) were measured in 24 normal tissues and pancreatic cancer lesions for each patient. From the biodistribution data, the organ doses and whole-body effective dose were calculated using OLINDA/EXM software.

RESULTS

There were no significant changes in vital signs or laboratory values that qualified as adverse events or serious adverse events. At 1 h post-injection, areas of high 18F-FP-R01-MG-F2 uptake included the pituitary gland, stomach, duodenum, kidneys, and bladder (average SUVmean: 9.7-14.5). Intermediate uptake was found in the normal pancreas (average SUVmean: 4.5). Mild uptake was found in the lungs and liver (average SUVmean < 1.0). The effective dose was calculated to be 2.538 × 10-2 mSv/MBq. Knottin PET/CT detected all known pancreatic tumors in the 15 patients, although it did not detect small peri-pancreatic lymph nodes of less than 1 cm in short diameter in two of three patients who had lymph node metastases at surgery. Knottin PET/CT detected distant metastases in the lungs (n = 5), liver (n = 4), and peritoneum (n = 2), confirmed by biopsy and/or contrast-enhanced CT.

CONCLUSION

18F-FP-R01-MG-F2 is a safe PET radiopharmaceutical with an effective dose comparable to other diagnostic agents. Evaluation of the primary pancreatic cancer and distant metastases with 18F-FP-R01-MG-F2 PET is feasible, but larger studies are required to define the role of this approach.

TRIAL REGISTRATION

NCT02683824.

A Clinical PET Imaging Tracer ([18F]DASA-23) to Monitor Pyruvate Kinase M2-Induced Glycolytic Reprogramming in Glioblastoma

PURPOSE

Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain. We describe the development, validation, and translation of a novel PET tracer to study PKM2 in GBM. We evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and patients with GBM.

EXPERIMENTAL DESIGN

[18F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/μmol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next, we produced [18F]DASA-23 under FDA oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with glioma.

RESULTS

In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from surrounding healthy brain tissue and had a tumor-to-brain ratio of 3.6 ± 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In patients with GBM, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced MRI. The uptake of [18F]DASA-23 was markedly elevated in GBMs compared with normal brain, and it identified a metabolic nonresponder within 1 week of treatment initiation.

CONCLUSIONS

We developed and translated [18F]DASA-23 as a new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

Synthesis and Characterization of 9-(4-[18F]Fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)-6-oxopurine as a Novel PET Agent for Mutant Herpes Simplex Virus Type 1 Thymidine Kinase Reporter Gene Imaging

PURPOSE

[¹⁸F]FHBG has been used as a positron emission tomography (PET) imaging tracer for the monitoring of herpes simplex virus type 1 thymidine kinase (HSV1-tk), a reporter gene for cell and gene therapy in humans. However, this tracer shows inadequate blood-brain barrier (BBB) penetration and, therefore, would be limited for accurate quantification of reporter gene expression in the brain. Here, we report the synthesis and evaluation of 9-(4-[¹⁸F]fluoro-3-(hydroxymethyl)butyl)-2(phenylthio)-6-oxopurine ([¹⁸F]FHBT) as a new PET tracer for imaging reporter gene expression of HSV1-tk and its mutant HSV1-sr39tk, with the aim of improved BBB penetration.

PROCEDURES

[¹⁸F]FHBT was prepared by using a tosylate precursor and [¹⁸F]KF. The cellular uptake of [¹⁸F]FHBT was performed in HSV1-sr39tk-positive (+) or HSV1-sr39tk-negative (-) MDA-MB-231 breast cancer cells. The specificity of [¹⁸F]FHBT to assess HSV1-sr39tk expression was evaluated by in vitro blocking studies using 1 mM of ganciclovir (GCV). Penetration of [¹⁸F]FHBT and [¹⁸F]FHBG across the BBB was assessed by dynamic PET imaging studies in normal mice.

RESULTS

The tosylate precursor reacted with [¹⁸F]KF using Kryptofix2.2.2 followed by deprotection to give [¹⁸F]FHBT in 10 % radiochemical yield (decay-corrected). The uptake of [¹⁸F]FHBT in HSV1-sr39tk (+) cells was significantly higher than that of HSV1-sr39tk (-) cells. In the presence of GCV (1 mM), the uptake of [¹⁸F]FHBT was significantly decreased, indicating that [¹⁸F]FHBT serves as a selective substrate of HSV1-sr39TK. PET images and time-activity curves of [¹⁸F]FHBT in the brain regions showed similar initial brain uptakes (~ 12.75 min) as [¹⁸F]FHBG (P > 0.855). Slower washout of [¹⁸F]FHBT was observed at the later time points (17.75 - 57.75 min, P > 0.207).

CONCLUSIONS

Although [¹⁸F]FHBT showed no statistically significant improvement of BBB permeability compared with [¹⁸F]FHBG, we have demonstrated that the 2-(phenylthio)-6-oxopurine backbone can serve as a novel scaffold for developing HSV1-tk/HSV1-sr39tk reporter gene imaging agents for additional research in the future.

Minicircles for a two-step blood biomarker and PET imaging early cancer detection strategy

Early cancer detection can dramatically increase treatment options and survival rates for patients, yet detection of early-stage tumors remains difficult. Here, we demonstrate a two-step strategy to detect and locate cancerous lesions by delivering tumor-activatable minicircle (MC) plasmids encoding a combination of blood-based and imaging reporter genes to tumor cells. We genetically engineered the MCs, under the control of the pan-tumor-specific Survivin promoter, to encode: 1) Gaussia Luciferase (GLuc), a secreted biomarker that can be easily assayed in blood samples; and 2) Herpes Simplex Virus Type 1 Thymidine Kinase mutant (HSV-1 sr39TK), a PET reporter gene that can be used for highly sensitive and quantitative imaging of the tumor location. We evaluated two methods of MC delivery, complexing the MCs with the chemical transfection reagent jetPEI or encapsulating the MCs in extracellular vesicles (EVs) derived from a human cervical cancer HeLa cell line. MCs delivered by EVs or jetPEI yielded significant expression of the reporter genes in cell culture versus MCs delivered without a transfection reagent. Secreted GLuc correlated with HSV-1 sr39TK expression with R² = 0.9676. MC complexation with jetPEI delivered a larger mass of MC for enhanced transfection, which was crucial for in vivo animal studies, where delivery of MCs via jetPEI resulted in GLuc and HSV-1 sr39TK expression at significantly higher levels than controls. To the best of our knowledge, this is the first report of the PET reporter gene HSV-1 sr39TK delivered via a tumor-activatable MC to tumor cells for an early cancer detection strategy. This work explores solutions to endogenous blood-based biomarker and molecular imaging limitations of early cancer detection strategies and elucidates the delivery capabilities and limitations of EVs.

BIMG-13. A NOVEL RADIOPHARMACEUTICAL ([18F]DASA-23) TO MONITOR PYRUVATE KINASE M2 INDUCED GLYCOLYTIC REPROGRAMMING IN GLIOBLASTOMA

BACKGROUND

Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain, making it an important biomarker of cancer glycolytic re-programming. We describe the bench-to-bedside development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. Specifically, we evaluated 1-((2-fluoro-6-[¹⁸F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([¹⁸F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients.

METHODS

[¹⁸F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/µmol and radiochemical purity >95%. We performed initial testing of [¹⁸F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [¹⁸F]DASA-23 under current Good Manufacturing Practices United States Food and Drug Administration (FDA) oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with gliomas.

RESULTS

In mouse imaging studies, [¹⁸F]DASA-23 clearly delineated the U87 GBM from the surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 ± 0.5. In human volunteers, [¹⁸F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [¹⁸F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [¹⁸F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it was able to identify a metabolic non-responder within 1-week of treatment initiation.

CONCLUSION

We developed and translated [¹⁸F]DASA-23 as a promising new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These encouraging results warrant further clinical evaluation of [¹⁸F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

Molecular Imaging of Chimeric Antigen Receptor T Cells by ICOS-ImmunoPET

PURPOSE

Immunomonitoring of chimeric antigen receptor (CAR) T cells relies primarily on their quantification in the peripheral blood, which inadequately quantifies their biodistribution and activation status in the tissues. Noninvasive molecular imaging of CAR T cells by PET is a promising approach with the ability to provide spatial, temporal, and functional information. Reported strategies rely on the incorporation of reporter transgenes or ex vivo biolabeling, significantly limiting the application of CAR T-cell molecular imaging. In this study, we assessed the ability of antibody-based PET (immunoPET) to noninvasively visualize CAR T cells.

EXPERIMENTAL DESIGN

After analyzing human CAR T cells in vitro and ex vivo from patient samples to identify candidate targets for immunoPET, we employed a syngeneic, orthotopic murine tumor model of lymphoma to assess the feasibility of in vivo tracking of CAR T cells by immunoPET using the 89Zr-DFO-anti-ICOS tracer, which we have previously reported.

RESULTS

Analysis of human CD19-CAR T cells during activation identified the Inducible T-cell COStimulator (ICOS) as a potential target for immunoPET. In a preclinical tumor model, 89Zr-DFO-ICOS mAb PET-CT imaging detected significantly higher signal in specific bone marrow-containing skeletal sites of CAR T-cell-treated mice compared with controls. Importantly, administration of ICOS-targeting antibodies at tracer doses did not interfere with CAR T-cell persistence and function.

CONCLUSIONS

This study highlights the potential of ICOS-immunoPET imaging for monitoring of CAR T-cell therapy, a strategy readily applicable to both commercially available and investigational CAR T cells.See related commentary by Volpe et al., p. 911.

New synthesis of 6″-[18 F]fluoromaltotriose for positron emission tomography imaging of bacterial infection

6″-[¹⁸ F]fluoromaltotriose is a positron emission tomography tracer that can differentiate between bacterial infection and inflammation in vivo. Bacteria-specific uptake of 6″-[¹⁸ F]fluoromaltotriose is attributed to the targeting of maltodextrin transporter in bacteria that is absent in mammalian cells. Herein, we report a new synthesis of 6″-[¹⁸ F]fluoromaltotriose as a key step for its clinical translation. In comparison with the previously reported synthesis, the new synthesis features unambiguous assignment of the fluorine-18 position on the maltotriose unit. The new method utilizes direct fluorination of 2″,3″,4″-tri-O-acetyl-6″-O-trifyl-α-D-glucopyranosyl-(1-4)-O-2',3',6'-tri-O-acetyl-α-D-glucopyranosyl-(1-4)-1,2,3,6-tetra-O-acetyl-D-glucopyranose followed by basic hydrolysis. Radiolabeling of the new maltotriose triflate precursor proceeds using a single HPLC purification step, which results in shorter reaction time in comparison with the previously reported synthesis. Successful synthesis of 6″-[¹⁸ F]fluoromaltotriose has been achieved in 3.5 ± 0.3% radiochemical yield (decay corrected, n = 7) and radiochemical purity above 95%. The efficient radiosynthesis of 6″-[¹⁸ F]fluoromaltotriose would be critical in advancing this positron emission tomography tracer into clinical trials for imaging bacterial infections.

Maltotriose-based probes for fluorescence and photoacoustic imaging of bacterial infections

Currently, there are no non-invasive tools to accurately diagnose wound and surgical site infections before they become systemic or cause significant anatomical damage. Fluorescence and photoacoustic imaging are cost-effective imaging modalities that can be used to noninvasively diagnose bacterial infections when paired with a molecularly targeted infection imaging agent. Here, we develop a fluorescent derivative of maltotriose (Cy7-1-maltotriose), which is shown to be taken up in a variety of gram-positive and gram-negative bacterial strains in vitro. In vivo fluorescence and photoacoustic imaging studies highlight the ability of this probe to detect infection, assess infection burden, and visualize the effectiveness of antibiotic treatment in E. coli-induced myositis and a clinically relevant S. aureus wound infection murine model. In addition, we show that maltotriose is an ideal scaffold for infection imaging agents encompassing better pharmacokinetic properties and in vivo stability than other maltodextrins (e.g. maltohexose).

NIMG-36. EVALUATION OF [18F]DASA-23 FOR NON-INVASIVE MEASUREMENT OF ABERRANTLY EXPRESSED PYRUVATE KINASE M2 IN GLIOMA: FIRST-IN-HUMAN STUDY

OBJECTIVES

We developed 1-((2-fluoro-6-(fluoro-[18F])phenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) as a novel radiopharmaceutical to measure pyruvate kinase M2 levels by positron emission tomography (PET). PKM2 catalyzes the final step in glycolysis, the key process of tumor metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in the healthy brain, making it an important biomarker of cancer glycolytic re-programming. Here, we report the first evaluation of [18F]DASA-23 in human healthy volunteers and subjects with low-grade (LGG) and high-grade glioma (HGG).

METHODS

[18F]DASA-23 was synthesized under GMP conditions. Brain [18F]DASA-23 PET/MRI scans (3T) were performed in human healthy volunteers (n=5) and subjects with LGG (n=3) and HGG (n=2). The PET imaging duration was 60 min and standardized uptake value (SUV) calculations were performed on the 30–60 min summed images. The maximum SUV in the tumor (TumorSUVmax) and contralateral white matter (WMSUVmax) were calculated.

RESULTS

[18F]DASA-23 specific activity was 2961±873 mCi/µmol (n=10) with radiochemical purity >95%, injected mass of 1.8±0.7 mcg, and dose of 0.3±0.02 mcg per kg body weight. In healthy volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared through the bladder and also showed uptake in the gallbladder, liver, and intestines over time. [18F]DASA-23 was found to be intact in plasma up to 10 min post-injection and 75% intact at 30 min post-injection. In subjects with glioma, TumorSUVmax was significantly greater in HGG (2.2±0.4, n=2) compared to LGG (0.8±0.3m n=3), p=0.02. In this early human series, the normalized ratio of TumorSUVmax/WMSUVmax was not significantly different between subjects with HGG (2.0±0.6) and LGG (1.0±0.4), p=0.1.

CONCLUSION

[18F]DASA-23 is a promising new imaging agent for the non-invasive delineation of LGG and HGG based on aberrantly expressed PKM2. An ongoing study is evaluating the utility of this agent in additional patients with intracranial malignancies (NCT03539731).

Identifying Hypoperfusion in Moyamoya Disease With Arterial Spin Labeling and an [15O]-Water Positron Emission Tomography/Magnetic Resonance Imaging Normative Database

Background and Purpose- Noninvasive imaging of brain perfusion has the potential to elucidate pathophysiological mechanisms underlying Moyamoya disease and enable clinical imaging of cerebral blood flow (CBF) to select revascularization therapies for patients. We used hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) technology to characterize the distribution of hypoperfusion in Moyamoya disease and its relationship to vessel stenosis severity, through comparisons with a normative perfusion database of healthy controls. Methods- To image CBF, we acquired [¹⁵O]-water PET as a reference and simultaneously acquired arterial spin labeling (ASL) MRI scans in 20 Moyamoya patients and 15 age-matched, healthy controls on a PET/MRI scanner. The ASL MRI scans included a standard single-delay ASL scan with postlabel delay of 2.0 s and a multidelay scan with 5 postlabel delays (0.7-3.0s) to estimate and account for arterial transit time in CBF quantification. The percent volume of hypoperfusion in patients (determined as the fifth percentile of CBF values in the healthy control database) was the outcome measure in a logistic regression model that included stenosis grade and location. Results- Logistic regression showed that anterior ( P<0.0001) and middle cerebral artery territory regions ( P=0.003) in Moyamoya patients were susceptible to hypoperfusion, whereas posterior regions were not. Cortical regions supplied by arteries with stenosis on MR angiography showed more hypoperfusion than normal arteries ( P=0.001), but the extent of hypoperfusion was not different between mild-moderate versus severe stenosis. Multidelay ASL did not perform differently from [¹⁵O]-water PET in detecting perfusion abnormalities, but standard ASL overestimated the extent of hypoperfusion in patients ( P=0.003). Conclusions- This simultaneous PET/MRI study supports the use of multidelay ASL MRI in clinical evaluation of Moyamoya disease in settings where nuclear medicine imaging is not available and application of a normative perfusion database to automatically identify abnormal CBF in patients.

Ammonium [11C]thiocyanate: revised preparation and reactivity studies of a versatile nucleophile for carbon-11 radiolabelling

Herein we report the preparation of ammonium [¹¹C]thiocyanate via the reaction of [¹¹C]CS₂ with ammonia. The [¹¹C]SCN^- ion is demonstrated as a potent nucleophile that can be used to readily generate a range of ¹¹C-labelled thiocyanate molecules in high conversions. Furthermore, novel ¹¹C-labelled thiazolone molecules can be easily prepared from the intermediate α-thiocyanatophenones via an acid mediated cyclisation reaction.

Long-Delay Arterial Spin Labeling Provides More Accurate Cerebral Blood Flow Measurements in Moyamoya Patients: A Simultaneous Positron Emission Tomography/MRI Study

BACKGROUND AND PURPOSE

Arterial spin labeling (ASL) MRI is a promising, noninvasive technique to image cerebral blood flow (CBF) but is difficult to use in cerebrovascular patients with abnormal, long arterial transit times through collateral pathways. To be clinically adopted, ASL must first be optimized and validated against a reference standard in these challenging patient cases.

METHODS

We compared standard-delay ASL (post-label delay=2.025 seconds), multidelay ASL (post-label delay=0.7-3.0 seconds), and long-label long-delay ASL acquisitions (post-label delay=4.0 seconds) against simultaneous [¹⁵O]-positron emission tomography (PET) CBF maps in 15 Moyamoya patients on a hybrid PET/MRI scanner. Dynamic susceptibility contrast was performed in each patient to identify areas of mild, moderate, and severe time-to-maximum (Tmax) delays. Relative CBF measurements by each ASL scan in 20 cortical regions were compared with the PET reference standard, and correlations were calculated for areas with moderate and severe Tmax delays.

RESULTS

Standard-delay ASL underestimated relative CBF by 20% in areas of severe Tmax delays, particularly in anterior and middle territories commonly affected by Moyamoya disease (P<0.001). Arterial transit times correction by multidelay acquisitions led to improved consistency with PET, but still underestimated CBF in the presence of long transit delays (P=0.02). Long-label long-delay ASL scans showed the strongest correlation relative to PET, and there was no difference in mean relative CBF between the modalities, even in areas of severe delays.

CONCLUSIONS

Post-label delay times of ≥4 seconds are needed and may be combined with multidelay strategies for robust ASL assessment of CBF in Moyamoya disease.

Carbon-11 radiolabelling of organosulfur compounds: (11) C synthesis of the progesterone receptor agonist tanaproget

Herein a new (11) C radiolabelling strategy for the fast and efficient synthesis of thioureas and related derivatives using the novel synthon, (11) CS2 , is reported. This approach has enabled the facile labelling of a potent progesterone receptor (PR) agonist, [(11) C]Tanaproget, by the intramolecular reaction of the acyclic aminohydroxyl precursor with (11) CS2 , which has potential applications as a positron emission tomography radioligand for cancer imaging.

Three-dimensional esophageal varix model quantification of variceal volume by high-resolution endoluminal US

BACKGROUND

The purpose of this study was to evaluate the accuracy and reproducibility of three-dimensional volume measurements by high-resolution endoluminal ultrasound in an esophageal varix model.

METHODS

An esophageal varix model was made by filling three esophageal dilatation catheters with various volumes of water. A 20 MHz ultrasonography transducer was then pulled along the length of the catheters at a constant rate (1.25 mm/sec) while videotaping the procedure. Cross-sectional surface area measurements of each catheter were taken every second and the cross-sectional surface area was multiplied by the length of each catheter, as determined by high-resolution endoluminal ultrasound, to determine the volume in each catheter. Interobserver variability was calculated, and three-dimensional reconstruction was performed.

RESULTS

The measured volumes corresponded closely with the actual volumes with an error ranging from 0% to 15.4%. The correlation between actual and measured volumes was r = 0.988. The interobserver variability ranged from r = 0.951 to r = 0.994. Actual esophageal varices were then imaged in a similar fashion to determine the feasibility of this method in patients with esophageal varices.

CONCLUSIONS

High-resolution endoluminal ultrasound is an accurate and reproducible method of measuring volumes in an esophageal varix model and can be used in a clinical setting to determine variceal volume. Volume studies are now underway in human subjects.

Role of flexible endoscopy in the evaluation of possible esophageal trauma after penetrating injuries

OBJECTIVE

In urban medical centers, penetrating injuries of the chest, neck, and head are frequently encountered due to the use of firearms and sharp weapons. Successful management of esophageal injury requires a high index of suspicion and prompt diagnosis. The role of flexible endoscopy, a readily available modality, has not been studied extensively in the management of potential esophageal injuries due to trauma.

METHODS

A retrospective chart review of 55 patients who underwent emergent flexible endoscopy for the evaluation of suspected penetrating esophageal injuries was performed to determine if endoscopy was safe and if it yielded information that altered patient management.

RESULTS

Flexible endoscopy was performed safely in all patients. It yielded a sensitivity of 100%, specificity of 92.4%, a negative predictive value of 100%, and a positive predictive value of 33.3% for detecting an esophageal injury. Although positive findings (prevalence, 3.6%) are infrequent, no esophageal injuries were missed. Endoscopy altered patient management in 38 (69.1%) patients.

CONCLUSIONS

Emergent flexible endoscopic examination of the esophagus is a safe and useful diagnostic tool in the early evaluation of penetrating injuries. Flexible endoscopy resulted in four negative surgical explorations, which was deemed acceptable by the Trauma Service, as the consequences of a missed esophageal injury is likely to be devastating.