Correlation of BOLD MRI with measures of tumor hypoxia in prostate cancer
Notice bibliographique
Résumé
Introduction: Tumor oxygen concentrations have prognostic and therapeutic implications in men with prostate cancer. A priori information on tumor oxygenation can be derived by using either Eppendorf measurements or taking additional biopsies after 2-nitroimidazole administration. However, widespread application of these techniques is limited as they are invasive and fail to provide spatial/volumetric information. Blood Oxygen Level Dependent (BOLD) MRI has been proposed for noninvasive three-dimensional characterization of oxygenation. This promising technique requires development and validation against gold-standard measures of tissue hypoxia. This preliminary study was conducted to explore the potential relationship between BOLD MRI, polarographic oxygen electrode measurements, and immunohistochemical evaluation of biopsy specimens. Material and Methods: 15 men with organ confined prostate cancer were enrolled in a prospective clinical trial of BOLD MRI acquisition. Nine men who received both BOLD MRI and Eppendorf measurements were evaluated, including 5 patients who also consented to additional needle-core biopsy immediately after the Eppendorf procedure. 2D gradient echo BOLD images were obtained (2DSPGR) using a torso phased array coil on a 1.5T MRI system with the following parameters: field of view 24cm, matrix 256×192, slice thickness/gap 8/2mm, TR/TE 100/5, 15, 25, 35 and 75ms, bandwidth 31.25kHz, flip angle 40°. From these an R2* map was generated. Using T2 weighted images an expert GU radiologist delineated regions of interest (ROI) suspicious for tumor. and the median R2* of the ROI was calculated. After MRI, transrectal ultrasound guided Eppendorf oxygen measurements were obtained from 4 different tracks within the tumor. Median pO2 and hypoxic fraction <5mm Hg (HP5) was measured. Spearman rho correlation was determined between median pO2, HP5 and R2*. Frozen biopsy tissue was immunostained for CA IX, HIF 1 alpha and GLUT 1 protein expression using antibody concentration of 1:100,1:100 and 1:1000 respectively. Protein expression was evaluated as a function of median pO2, HP5, and median R2*. Results: 8 out of 9 men had low-intermediate risk prostate cancer with median prostate volume of 44 cc (26–60 cc) and median PSA of 7ng/ml (5.5–16). A total of 756 pO2 measurements were obtained with a median pO2 of 8.3mm Hg (0–47.8mm Hg) and median HP5 of 21.4% (0–83.3%). The median R2* was 1712 (842–2307). Correlation was observed between HP5 and R2* (R2=0.80, p=0.01), and between pO2 and R2* (R2=–0.68, p=0.04). While GLUT 1 and HIF 1 expression was observed in all patients, CA IX was expressed only in one patient with the highest HP5 (77%), pO2 (1.40mm Hg), and second highest median R2* (1712). Discussion: In a preliminary evaluation, correlation between R2* and measures of tumor hypoxia (HP5, median pO2, and CAIX expression) is observed. These findings suggest that BOLD MRI may be a biomarker of hypoxia in prostate cancer, warranting further investigation. Future work will develop more robust and quantitative MRI methodologies, and validate such metrics with improved spatial-temporal registration of gold-standard measures of tissue hypoxia.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».