Preclinical evaluation and validation of [18F]HX4, a promising hypoxia marker for PET imaging.

Hypoxia has been shown to be an important microenvironmental parameter influencing tumor progression and treatment efficacy. Patient guidance for hypoxia-targeted therapy requires evaluation of tumor oxygenation, preferably in a noninvasive manner. The aim of this study was to evaluate and validate the uptake of [(18)F]HX4, a novel developed hypoxia marker for PET imaging.

Residual metabolic tumor activity after chemo-radiotherapy is mainly located in initially high FDG uptake areas in rectal cancer.

Purpose: Recent literature suggests that tumor cells and areas within tumors with a high initial FDG uptake might be more resistant to (chemo)radiotherapy ((C)RT). This study was undertaken to test this hypothesis in rectal cancer using rigid and non-rigid image registration.

Patients And Methods: Twenty-eight patients, diagnosed with locally advanced rectal cancer and referred for pre-operative treatment with CRT were included in this study.

Repeated positron emission tomography-computed tomography and perfusion-computed tomography imaging in rectal cancer: fluorodeoxyglucose uptake corresponds with tumor perfusion.

Purpose: The purpose of this study was to analyze both the intratumoral fluorodeoxyglucose (FDG) uptake and perfusion within rectal tumors before and after hypofractionated radiotherapy.

Methods And Materials: Rectal cancer patients, referred for preoperative hypofractionated radiotherapy (RT), underwent FDG-positron emission tomography (PET)-computed tomography (CT) and perfusion-CT (pCT) imaging before the start of hypofractionated RT and at the day of the last RT fraction. The pCT-images were analyzed using the extended Kety model, quantifying tumor perfusion with the pharmacokinetic parameters K(trans), v(e), and v(p).

PET-based treatment response evaluation in rectal cancer: prediction and validation.

Purpose: To develop a positron emission tomography (PET)-based response prediction model to differentiate pathological responders from nonresponders. The predictive strength of the model was validated in a second patient group, treated and imaged identical to the patients on which the predictive model was based.

Methods And Materials: Fifty-one rectal cancer patients were prospectively included in this study.

FDG-PET provides the best correlation with the tumor specimen compared to MRI and CT in rectal cancer.

Purpose: To compare CT-, MR- and PET-CT based tumor length measurements in rectal cancer with pathology.

Patients And Methods: Twenty-six rectal cancer patients underwent both MR and PET-CT imaging followed by short-course radiotherapy (RT 5×5 Gy) and surgery within 3 days after RT. Tumor length was measured manually and independently by 2 observers on CT, MR and PET.

Development and external validation of a predictive model for pathological complete response of rectal cancer patients including sequential PET-CT imaging.

Purpose: To develop and validate an accurate predictive model and a nomogram for pathologic complete response (pCR) after chemoradiotherapy (CRT) for rectal cancer based on clinical and sequential PET-CT data. Accurate prediction could enable more individualised surgical approaches, including less extensive resection or even a wait-and-see policy.

Methods And Materials: Population based databases from 953 patients were collected from four different institutes and divided into three groups: clinical factors (training: 677 patients, validation: 85 patients), pre-CRT PET-CT (training: 114 patients, validation: 37 patients) and post-CRT PET-CT (training: 107 patients, validation: 55 patients).

PET imaging of hypoxia using [18F]HX4: a phase I trial.

Background And Purpose: Noninvasive PET imaging of tumour hypoxia could help in the selection of those patients who could benefit from chemotherapy or radiation with specific antihypoxic treatments such as bioreductive drugs or hypoxic radiosensitizers. In this phase I trial, we aimed to determine the toxicity of [(18)F]HX4, a member of the 2-nitroimidazole family, at different dose levels. The secondary aim was to analyse image quality related to the HX4 dose and the timing of imaging.

Blood glucose level normalization and accurate timing improves the accuracy of PET-based treatment response predictions in rectal cancer.

Purpose: To quantify the influence of fluctuating blood glucose level (BGLs) and the timing of PET acquisition on PET-based predictions of the pathological treatment response in rectal cancer.

Material And Methods: Thirty patients, diagnosed with locally advanced-rectal-cancer (LARC), were included in this prospective study. Sequential FDG-PET-CT investigations were performed at four time points during and after pre-operative radiochemotherapy (RCT).

Evaluation of early metabolic responses in rectal cancer during combined radiochemotherapy or radiotherapy alone: sequential FDG-PET-CT findings.

Background And Purpose: The purpose of this study was to prospectively investigate metabolic changes of rectal tumors after 1 week of treatment of either radiochemotherapy (28 x 1.8 Gy+Capecitabine) (RCT) or hypofractionated radiotherapy (5 x 5 Gy) alone (RT).

Materials And Methods: Fourty-six rectal cancer patients, 25 RCT- and 21 RT-patients, were included in this study.

Tumor perfusion increases during hypofractionated short-course radiotherapy in rectal cancer: sequential perfusion-CT findings.

Purpose: The purpose of this study was to investigate perfusion of rectal tumors and to determine early responses to short-course hypofractionated radiotherapy (RT).

Material And Methods: Twenty-three rectal cancer patients were included, which underwent perfusion-CT imaging before (pre-scan) and after treatment (post-scan). Contrast-enhancement was measured in tumor and muscle tissues and in the external iliac artery.

Comparison between perfusion computed tomography and dynamic contrast-enhanced magnetic resonance imaging in rectal cancer.

Purpose: To compare pretreatment scans with perfusion computed tomography (pCT) vs. dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rectal tumors.

Methods And Materials: Nineteen patients diagnosed with rectal cancer were included in this prospective study.

Accurate prediction of pathological rectal tumor response after two weeks of preoperative radiochemotherapy using (18)F-fluorodeoxyglucose-positron emission tomography-computed tomography imaging.

Purpose: To determine the optimal time point for repeated (18)F-fluorodeoxyglucose-positron emission tomography (PET)-CT imaging during preoperative radiochemotherapy (RCT) and the best predictive factor for the prediction of pathological treatment response in patients with locally advanced rectal cancer.

Methods And Materials: A total of 30 patients referred for preoperative RCT treatment were included in this prospective study. All patients underwent sequential PET-CT imaging at four time points: prior to therapy, at day 8 and 15 during RCT, and shortly before surgery.

Tumor delineation based on time-activity curve differences assessed with dynamic fluorodeoxyglucose positron emission tomography-computed tomography in rectal cancer patients.

Purpose: To develop an unsupervised tumor delineation method based on time-activity curve (TAC) shape differences between tumor tissue and healthy tissue and to compare the resulting contour with the two tumor contouring methods mostly used nowadays.

Methods And Materials: Dynamic positron emission tomography-computed tomography (PET-CT) acquisition was performed for 60 min starting directly after fluorodeoxyglucose (FDG) injection. After acquisition and reconstruction, the data were filtered to attenuate noise.