Investigations of (99m)Tc-labeled glucarate as a SPECT radiotracer for non-small cell lung cancer (NSCLC) and potential tumor uptake mechanism

A prospective study to compare the diagnostic accuracy of 99mTc-CNDG SPECT/CT and contrast-enhanced CT in staging of non-small cell lung cancer

OBJECTIVE

To explore the value of 99mTc-isonitrile deoxyglucosamine (CNDG) SPECT/CT in the staging and resectability diagnosis of non-small cell lung cancer (NSCLC) compared with contrast-enhanced CT (CECT).

METHODS

This research was approved by the hospital ethics review committee. Sixty-three patients with NSCLC received 99mTc-CNDG SPECT/CT, CECT and initial TNM staging before treatment. Thirty-three patients who underwent radical surgery underwent postoperative pathological TNM staging as the reference standard. Another thirty patients underwent radiochemotherapy; among them, the reference standard of 7 patients of N staging and 5 patients of M staging was based on biopsy pathology, and the diagnosis of the remaining lesions was confirmed by at least one different image or clinical imaging follow-up for more than 3 months. The McNemar test and receiver operating characteristic (ROC) curve analysis were used to compare the diagnostic accuracy of staging and resectability of 99mTc-CNDG SPECT/CT and CECT in NSCLC, respectively.

RESULTS

For all patients and surgical patients, the accuracies of 99mTc-CNDG SPECT/CT in diagnosing the T stage and N stage were higher than those of CECT (all patients: 90.5%, 88.9% vs. 79.4%, 60.3%; surgical patients: 81.8%, 78.8% vs. 60.6%, 51.5%), and the differences were statistically significant (all patients: T stage, P = 0.016; N stage, P = 0.000; surgical patients: T stage, P = 0.016; N stage, P = 0.004). For all patients, the accuracy of 99mTc-CNDG SPECT/CT in diagnosing the M stage was higher than that of CECT (96.8% vs. 90.5%), but the difference was not statistically significant (P = 0.289). ROC curve analysis showed that the accuracy of 99mTc-CNDG SPECT/CT in diagnosing the potential resectability of NSCLC was significantly better than that of CECT (P = 0.046).

CONCLUSION

This preliminary clinical study shows that 99mTc-CNDG SPECT/CT is of great value for accurate clinical staging of NSCLC compared with CECT and can significantly improve the accuracy of resectability diagnosis.

Untiring Pursuit for Glucarate-Based Molecular Imaging Probes

Glucarate, a physiologic end-product of the D-glucuronic acid pathway in mammals, is a six-carbon dicarboxylic acid with a wide range of uses. Glucarate-based molecular imaging probes including [^99mTc]glucarate and [¹⁸F]glucarate have been developed and demonstrated to have infarct/necrosis-avid and/or tumor-seeking properties, showing potential applications in early detection of myocardial infarction, evaluation of tissue viability, monitoring of therapeutic effectiveness, and noninvasive imaging of certain tumors including drug-resistant ones. The mechanism by which [^99mTc]glucarate localizes in acute necrotic tissues has been demonstrated to be largely attributable to its binding to the positively charged histones, which become accessible after the disruption of the cell and nuclear membranes as a result of irreversible damage, while the tumor-seeking mechanism of [^99mTc]glucarate has been found to be closely related to glucose transporter 5 expression. Moreover, the recently developed [¹⁸F]glucarate provides a new alternative probe for positron emission tomography imaging and may have potential advantages over [^99mTc]glucarate. In this review, we present the untiring pursuit for glucarate-based molecular imaging probes as infarct/necrosis-avid agent and/or tumor-seeking agent. Moreover, the limitations and the prospects for future research of glucarate-based molecular probes are also discussed.