Detection and quantification of small and low-uptake lesions for differentiated thyroid carcinoma using non-time-of-flight iodine-124 PET/MRI

IF 3.2 2区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Medical physics Pub Date : 2024-11-26 DOI:10.1002/mp.17535

Maike E. Lindemann, Walter Jentzen, David Kersting, Pedro Fragoso Costa, Alina Küper, Lale Umutlu, Ken Herrmann, Harald H. Quick

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引用次数: 0

Abstract

Background

124-iodine (¹²⁴I) is used for positron emission tomography (PET) diagnostics and therapy planning in patients with differentiated thyroid cancer (DTC). Small lesion sizes (<10 mm) and low ¹²⁴I uptake are challenging conditions for the detection of DTC lymph node lesions.

Purpose

The aim of this study was to systematically investigate the lesion detectability and quantification performance under clinically challenging imaging conditions using non-time-of-flight (TOF) PET/magnetic resonance imaging (MRI) in the clinical context of radionuclide therapy planning of DTC patients.

Methods

PET/MR measurements were performed on the Siemens Biograph mMR using a small lesion NEMA-like phantom (six glass spheres, diameters 3.7–9.7 mm). 60 min list-mode data were acquired for nine activity concentrations (AC) ranging from 25 kBq/mL to 0.25 kBq/mL using a sphere-to-background ratio of 20:1. PET list-mode data were divided into five timeframes (60, 30, 16, 8, and 4 min) and reconstructed using either ordered-subsets expectation maximization (OSEM) or OSEM+ point spread function (PSF) algorithm. For all reconstructions, the smallest detectable sphere size was investigated in a human observer study. Partial volume effect (PVE) corrected PET images (contour and oversize-based approach) were analyzed considering a ± 30% deviation range between imaged and true AC as acceptable. Clinical data of eight DTC patients with small lymph node lesions were evaluated to assess agreement between the PVE correction approaches.

Results

Longer PET acquisition times, higher ACs, and PSF reconstructions resulted in improved PET image quality and overall improved lesion detectability. The smallest 3.7 mm sphere was only visible under the best imaging conditions. Using a typical clinical ¹²⁴I whole-body PET/MRI protocol with an acquisition time of 8 min using OSEM reconstructions, all lesions of ≥ 6.5 mm in diameter could be detected and the quantification provided reliable results approximately above 5.0 kBq/mL. An accurate quantification of ACs in the 4.8 mm sphere was not feasible in this study. In the clinical evaluation of 10 lesions, a good agreement between oversize- and contour-based PVE corrections was observed (<15% deviation).

Conclusions

The results showed that a reliable quantification of ¹²⁴I uptake with PET/MRI is feasible and, therefore, could be used to perform radioiodine pre-therapy lesion dosimetry and individualized therapy planning in DTC patients.

Abstract Image

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利用非飞行时间碘-124 PET/MRI 检测和量化分化型甲状腺癌的小病灶和低摄取病灶。

背景：124碘（124I）用于分化型甲状腺癌（DTC）患者的正电子发射断层扫描（PET）诊断和治疗计划。目的：本研究的目的是系统研究在对 DTC 患者进行放射性核素治疗计划的临床背景下，使用非飞行时间 PET（TOF）/磁共振成像（MRI）在具有临床挑战性的成像条件下的病变可探测性和量化性能：PET/MR 测量是在西门子 Biograph mMR 上使用小病灶 NEMA 类模型（六个玻璃球，直径 3.7-9.7 毫米）进行的。使用 20:1 的球-背景比，采集了从 25 kBq/mL 到 0.25 kBq/mL 的九种活性浓度 (AC) 的 60 分钟列表模式数据。PET 列表模式数据分为五个时间段（60、30、16、8 和 4 分钟），并使用有序子集期望最大化（OSEM）或 OSEM+ 点扩散函数（PSF）算法进行重建。在所有重建中，人类观察者研究调查了可检测到的最小球体大小。对部分容积效应（PVE）校正 PET 图像（基于轮廓和超大尺寸的方法）进行了分析，认为成像与真实 AC 之间的偏差范围在 ± 30% 之间是可以接受的。评估了八名淋巴结病变较小的 DTC 患者的临床数据，以评估 PVE 校正方法之间的一致性：结果：更长的 PET 采集时间、更高的 AC 值和 PSF 重建提高了 PET 图像质量，并全面改善了病灶的可探测性。只有在最佳成像条件下才能看到最小的 3.7 毫米球体。采用典型的临床 124I 全身 PET/MRI 方案，使用 OSEM 重建，采集时间为 8 分钟，可检测到直径≥ 6.5 毫米的所有病灶，量化结果可靠，约高于 5.0 kBq/mL。本研究无法对 4.8 毫米球内的 AC 进行精确定量。在对 10 个病灶进行的临床评估中，观察到基于超大尺寸和轮廓的 PVE 校正之间存在良好的一致性（结论：结果表明，利用 PET/MRI 对 124I 摄取进行可靠的量化是可行的，因此可用于对 DTC 患者进行放射性碘治疗前病灶剂量测定和个体化治疗计划。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Medical physics 医学-核医学

CiteScore

6.80

自引率

15.80%

发文量

660

审稿时长

1.7 months

期刊介绍： Medical Physics publishes original, high impact physics, imaging science, and engineering research that advances patient diagnosis and therapy through contributions in 1) Basic science developments with high potential for clinical translation 2) Clinical applications of cutting edge engineering and physics innovations 3) Broadly applicable and innovative clinical physics developments Medical Physics is a journal of global scope and reach. By publishing in Medical Physics your research will reach an international, multidisciplinary audience including practicing medical physicists as well as physics- and engineering based translational scientists. We work closely with authors of promising articles to improve their quality.