Delayed hepatic signal recovery on ferucarbotran-enhanced magnetic resonance images in a rat model with regional liver irradiation

Abstract

Superparamagnetic iron oxide-enhanced MR imaging could demonstrate signal recovery delay in irradiated areas of rat livers. It seems that the signal recovery delay in irradiated areas was due to SPIO-derived iron deposition. Hepatic signal recovery could be a novel diagnostic marker for delineation of irradiated areas.

Persistent T2*-hypointensity of the liver parenchyma after irradiation to the SPIO-accumulated liver: An imaging marker for responses to radiotherapy in hepatic malignancies

“…However, iron deposition persisted for more than 7 days in the liver parenchyma treated with high‐dose irradiation, and produced T2*‐weighted hypointense areas at 9.4 tesla, as previously reported in an animal study by Furuta et al This study attributed persistent hepatic iron deposition to the delayed clearance of SPIO particles from the irradiated liver, which have been due to radiation‐induced impairments in the exocytotic functions of KCs to SPIO particles. The results of the present study suggest that a similar mechanism gave rise to the T2*‐weighted hypointense areas in irradiated liver areas, and these areas were observable even at clinically‐relevant 3 tesla.…”

Magnetic Resonance-Based Visualization of Thermal Ablative Margins Around Hepatic Tumors by Means of Systemic Ferucarbotran Administration Before Radiofrequency Ablation

“…21,22 Hence, SPIO crystals rarely remain in the normal liver tissue even after 7 days in the condition under which Kupffer cells function well. Therefore, we deduce that SPIO degradation in the ablated liver tissue may be very different from that in the normal liver.…”

MR signal changes in superparamagnetic iron oxide nanoparticle‐labeled macrophages in response to X irradiation

“…Because R 2 ′ exponentially decreased with a coefficient of 0.3 in the 2 Gy irradiated J774A.1 samples, we estimated the duration at around 10 d for the intracellular SPIONs to be reduced to 5% of the baseline level (ln 20 divided by 0.3 yields 10.0 d). The estimated speed of intracellular SPION disappearance is slightly slower than that at approximately 1 week in normal macrophages (Kupffer cells) in the liver . X irradiation at a certain dose (2 Gy for J774A.1) may slow down, but not eliminate, the ability of macrophages to degrade SPIONs, even when cell growth is suppressed.…”

“…A possible application of this technique may be MRI of SPION‐labeled macrophages in the liver to visualize areas where the labeled macrophages are damaged by X irradiation. Furuta and coworkers have indeed revealed in their animal experiments that resident macrophages or Kupffer cells labeled with SPIONs and subsequently damaged by X irradiation can generate low T 2 *‐weighted signals for a longer duration than non‐irradiated cells . Consequently, X‐irradiated liver parenchyma was clearly delineated several days after X irradiation, presumably because the irradiated macrophages retained the intracellular SPION label for a certain period of time in vivo.…”

“…The estimated speed of intracellular SPION disappearance is slightly slower than that at approximately 1 week in normal macrophages (Kupffer cells) in the liver. 12,27 X irradiation at a certain dose (2 Gy for J774A.1) may slow down, but not eliminate, the ability of macrophages to degrade SPIONs, even when cell growth is suppressed.…”