MR assessment of changes of tumor in response to hyperbaric oxygen treatment

Abstract

Enhancement of image intensity, using the T 1 -weighted spoiled gradient-echo (SPGR) sequence, was measured in SCC tumor implanted in the flank of C3H mice while they were subjected to several types of oxygenation challenges inside a hyperbaric chamber designed and constructed to fit in an MRI resonator. The central portions of the tumor gave a positive enhancement, while the periphery showed signal reduction during both normobaric (NBO) and hyperbaric (HBO) oxygen challenges. In the contralateral normal leg, nearly 70% of the region showed a decrease in intensity, and the rest showed a positive enhancement. The positive signal enhancement was markedly greater under HBO compared to NBO. Calculated R 1 , R 2 , and M 0 maps from multivariate fitting of images acquired by a multislice multiecho (MSME) sequence with variable TR before, during, and after HBO treatment confirm that the source of SPGR signal enhancement in the tumor is associated with shortening of T 1 . Magn Reson Med 56:240 -246,

Utility Decay Rates of T1-Weighted Magnetic Resonance Imaging Contrast Based on Redox-Sensitive Paramagnetic Nitroxyl Contrast Agents

“…31,32) Recent high-power magnet MRI instrumentation, such as 4.7 T, with a T 1 -weighted SPGR pulse sequence, has enabled us to examine T 1 enhancement sensitively, for example, T 1 enhancement under hyperbaric oxygenation in mice. 33) Scan parameters used in the phantom experiment in this paper were employed according to the parameters used in our previous paper. 33) Suitable values of these parameters were estimated by previous simulation, and then decided through practical experiments to detect T 1 enhancement by oxygen in vivo.…”

“…33) Scan parameters used in the phantom experiment in this paper were employed according to the parameters used in our previous paper. 33) Suitable values of these parameters were estimated by previous simulation, and then decided through practical experiments to detect T 1 enhancement by oxygen in vivo. When nitroxyl contrast agents were applied to the same T 1 -weighted pulse sequence scan, [27][28][29] a more pronounced contrast difference (DM%) was expected to be obtained.…”

Vatuximab(Trademark): Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

“…However, R1L1 and R0L0 both show growth rates considerably slower than control and greatly increased DCE response after 7 days. It is tempting to suggest that this represents vascular normalization as postulated by Rakesh Jain in his analysis of vascular targeting agents (38).…”

“…Following intravenous infusion, these reporter molecules are trapped in tissues in the absence of oxygen, very much like molecules such as pimonidazole and EF5 that are widely used in histological assessment of hypoxia (33). Many such reporter molecules have been developed for different modalities such as NMR (34)(35)(36), positron emission tomography (PET) (37)(38)(39)(40) and single photon emission computed tomography (SPECT) (41,42). The red shift of the fluorescence of green fluorescent protein (GFP) under hypoxic conditions has also been used to image hypoxia by fluorescence imaging (43).…”

Intracellular and Extracellular Redox Environments Surrounding Redox-Sensitive Contrast Agents under Oxidative Atmosphere

“…18,19) Therefore efforts to increase oxygen concentration and/or to change redox conditions in cancer/ tumor tissues have been attempted to enhance chemical and/ or radiation sensitivity in cancer/tumor tissues. 20,21) When animals breathe 100% oxygen, it is expected that the re-oxidation of hydroxylamines to the corresponding nitroxyl radicals may be easier, because increased oxygen concentration in blood and tissues may induce an oxidative atmosphere. In vivo redox reactions of nitroxyl contrast agents in bile and blood under an oxidative atmosphere were investigated using normal healthy Wistar rats.…”