Department of Radiology, Addenbrooke's Hospital and University of Cambridge School of Clinical Medicine, Box 218, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK.
Eur Radiol. 2022 Oct;32(10):7155-7162. doi: 10.1007/s00330-022-08929-7. Epub 2022 Jun 22.
Hyperpolarised [1-C]pyruvate MRI (HP-C-MRI) is an emerging metabolic imaging technique that has shown promise for evaluating prostate cancer (PCa) aggressiveness. Accurate tumour delineation on HP-C-MRI is vital for quantitative assessment of the underlying tissue metabolism. However, there is no consensus on the optimum method for segmenting HP-C-MRI, and whole-mount pathology (WMP) as the histopathological gold-standard is only available for surgical patients. Although proton MRI can be used for tumour delineation, this approach significantly underestimates tumour volume, and metabolic tumour segmentation based on HP-C-MRI could provide an important functional metric of tumour volume. In this study, we quantified metabolism using HP-C-MRI and segmentation approaches based on WMP maps, H-MRI-derived T-weighted imaging (T2WI), and HP-C-MRI-derived total carbon signal-to-noise ratio maps (TC-SNR) with an SNR threshold of 5.0. C-labelled pyruvate SNR, lactate SNR, TC-SNR, and the pyruvate-to-lactate exchange rate constant (k) were significantly higher when measured using the TC-SNR-guided approach, which also corresponded to a significantly higher tumour epithelial expression on RNAscope imaging of the enzyme catalysing pyruvate-to-lactate metabolism (lactate dehydrogenase (LDH)). However, linear regression and Bland-Altman analyses demonstrated a strong linear relationship between all three segmentation approaches, which correlated significantly with RNA-scope-derived epithelial LDH expression. These results suggest that standard-of-care T2WI and TC-SNR maps could be used as clinical reference tools for segmenting localised PCa on HP-C-MRI in the absence of the WMP gold standard. The TC-SNR-guided approach could be used clinically to target biopsies towards highly glycolytic tumour areas and therefore to sample aggressive disease with higher precision. KEY POINTS: • T2WI- and TC-SNR-guided segmentations can be used in all PCa patients and do not explicitly require WMP maps. • Agreement between the three segmentation approaches is biologically validated by their strong relationship with epithelial LDH mRNA expression. • The TC-SNR-guided approach can potentially be used to identify occult disease on H-MRI and target the most glycolytically active regions.
1-13 碳丙酮酸磁共振波谱成像（HP-C-MRI）是一种新兴的代谢成像技术，已显示出评估前列腺癌（PCa）侵袭性的潜力。在 HP-C-MRI 上准确勾画肿瘤对于评估潜在组织代谢至关重要。然而，目前还没有关于 HP-C-MRI 最佳分割方法的共识，而全器官病理学（WMP）作为组织学金标准仅适用于手术患者。虽然质子 MRI 可用于肿瘤勾画，但这种方法会显著低估肿瘤体积，而基于 HP-C-MRI 的代谢肿瘤分割则可以提供肿瘤体积的重要功能指标。在这项研究中，我们使用 HP-C-MRI 并基于 WMP 图谱、H-MRI 衍生的 T 加权成像（T2WI）和 HP-C-MRI 衍生的总碳信号与噪声比图谱（TC-SNR）进行分割，其中 SNR 阈值为 5.0。使用 TC-SNR 指导方法测量时，标记的丙酮酸 SNR、乳酸 SNR、TC-SNR 和丙酮酸到乳酸的代谢酶（乳酸脱氢酶（LDH））的交换率常数（k）明显更高，这也与 RNAscope 酶促丙酮酸到乳酸代谢成像上的肿瘤上皮表达明显更高相对应。然而，线性回归和 Bland-Altman 分析表明，所有三种分割方法之间具有很强的线性关系，并且与 RNA-scope 衍生的上皮 LDH 表达显著相关。这些结果表明，在缺乏 WMP 金标准的情况下，标准 T2WI 和 TC-SNR 图谱可作为 HP-C-MRI 局部 PCa 分割的临床参考工具。TC-SNR 指导的方法可在临床上用于将活检靶向到高度糖酵解的肿瘤区域，从而以更高的精度采样侵袭性疾病。关键点：
T2WI 和 TC-SNR 引导的分割可用于所有 PCa 患者，并且不需要明确的 WMP 图谱。
三种分割方法之间的一致性通过与上皮 LDH mRNA 表达的强烈关系得到生物学验证。
TC-SNR 指导的方法可用于识别 H-MRI 上的隐匿性疾病并靶向最具糖酵解活性的区域。
