Background and Aims Advances in cancer treatment have improved survival; however, local recurrence and metastatic disease—the principal causes of cancer mortality—have limited the ability to achieve durable remissions. Local recurrences arise from latent tumor cells that survive therapy and are often not detectable by conventional clinical imaging techniques. Local recurrence after transarterial embolization (TAE) of hepatocellular carcinoma (HCC) provides a compelling clinical correlate of this phenomenon. In response to TAE‐induced ischemia, HCC cells adapt their growth program to effect a latent phenotype that precedes local recurrence. Approach and Results In this study, we characterized and leveraged the metabolic reprogramming demonstrated by latent HCC cells in response to TAE‐induced ischemia to enable their detection in vivo using dynamic nuclear polarization (DNP) magnetic resonance spectroscopic imaging (MRSI) of 13carbon‐labeled substrates. Under TAE‐induced ischemia, latent HCC cells demonstrated reduced metabolism and developed a dependence on glycolytic flux to lactate. Despite the hypometabolic state of these cells, DNP‐MRSI of 1‐13C‐pyruvate and its downstream metabolites, 1‐13C‐lactate and 1‐13C‐alanine, predicted histological viability. Conclusions These studies provide a paradigm for imaging latent, treatment‐refractory cancer cells, suggesting that DNP‐MRSI provides a technology for this application.

◥Purpose: Targeted therapies for cancer have accelerated the need for functional imaging strategies that inform therapeutic efficacy. This study assesses the potential of functional genetic screening to integrate therapeutic target identification with imaging probe selection through a proof-of-principle characterization of a therapyprobe pair using dynamic nuclear polarization (DNP)-enhanced magnetic resonance spectroscopic imaging (MRSI).Experimental Design: CRISPR-negative selection screens from a public dataset were used to identify the relative dependence of 625 cancer cell lines on 18,333 genes. Follow-up screening was performed in hepatocellular carcinoma with a focused CRISPR library targeting imaging-related genes. Hyperpolarized [1-13 C]-pyruvate was injected before and after lactate dehydrogenase inhibitor (LDHi) administration in male Wistar rats with autochthonous hepatocellular carcinoma. MRSI evaluated intratumoral pyruvate metabolism, while T 2 -weighted segmentations quantified tumor growth.Results: Genetic screening data identified differential metabolic vulnerabilities in 17 unique cancer types that could be imaged with existing probes. Among these, hepatocellular carcinoma required lactate dehydrogenase (LDH) for growth more than the 29 other cancer types in this database. LDH inhibition led to a decrease in lactate generation (P < 0.001) and precipitated dose-dependent growth inhibition (P < 0.01 overall, P < 0.05 for dose dependence). Intratumoral alanine production after inhibition predicted the degree of growth reduction (P < 0.001).Conclusions: These findings demonstrate that DNP-MRSI of LDH activity using hyperpolarized [1-13 C]-pyruvate is a theranostic strategy for hepatocellular carcinoma, enabling quantification of intratumoral LDHi pharmacodynamics and therapeutic efficacy prediction. This work lays the foundation for a novel theranostic platform wherein functional genetic screening informs imaging probe selection to quantify therapeutic efficacy on a cancer-bycancer basis.

Purpose: To evaluate the utility of visualizing pre-procedure MRI in three-dimensional (3D) space using augmented reality (AR) prior to transarterial embolization (TAE) of hepatocellular carcinoma (HCC) in a preclinical model. Materials and Methods:A prospective study with a total of 28 rats with diethylnitrosamine (DEN)-induced HCC and tumors greater than 5 mm treated with TAE were included. In 12 rats, 3D AR visualization of the pre-procedure MRI was performed prior to TAE. Procedural metrics including catheterization time and radiation exposure were compared to a prospective cohort of 16 rats in whom TAE was performed without AR. An additional cohort of 15 retrospective cases were identified and combined with the prospective control cohort (n=31) to improve statistical power.Results: A reduction in fluoroscopy time was observed after AR when compared prospectively from 11.7 to 7.4 min (37%; p=0.12), which did not reach statistical significance; however, when compared to combined prospective and retrospective controls, the reduction in fluoroscopy time was significant from 14.1 to 7.4 min (48%; p=0.01). A reduction in total catheterization time was also observed after AR when compared prospectively from 42.7 to 31.0 min (27%; p=0.11), which did not reach statistical significance. No significant differences were seen in dose area product (DAP) or air kerma (AK) prospectively.Conclusions: 3D AR visualization of pre-procedural imaging may aid in the reduction of procedural metrics in a preclinical model of TACE. These data support the need for further studies to evaluate the potential of AR on endovascular oncologic interventions.

<p>(Rows 1 & 2) Parametric maps of intratumoral metabolite ratios, including lactate-to-pyruvate, alanine-to-pyruvate, and alanine-to-lactate before (row 1) and after (row 2) LDHi. These data demonstrate an increase in intratumoral pyruvate, a decrease in intratumoral lactate, and an increase in intratumoral alanine after LDHi. All maps were generated from the acquisition highlighted in Figure 2A. [P=pyruvate, L=lactate, A=alanine]</p>

<p>Schematic depicting metabolic pathways that can be analyzed with DNP probes. The background of the figure is a representation of the KEGG human global metabolism map (01100) that was generated in R using Pathview. As in Figure 1A, purple nodes correspond to previously polarized probes. Pink nodes correspond to intermediates that have either been (i) directly visualized after injection of a DNP probe or (ii) have not been directly identified but precede a downstream intermediate that has been directly visualized. Yellow nodes correspond to metabolites that may serve as future molecular imaging probes, as suggested by the data provided in Supplementary Table 1. Dashed lines correspond to an enzyme or group of enzymes connecting DNP-MRS probes and/or intermediates. Colored semi-circles correspond to cancer types that may be imaged with the subjacent, lettered DNP-MRS probe, as described in Supplementary Table 1.</p>