¹H MRS phantom studies of BNCT ¹⁰B‒carrier, BPA–F using STEAM and PRESS MRS sequences: Detection limit and quantification

Abstract

The quantification of boron neutron capture therapy (BNCT)10B‒carrier, L‒p‒boronophenylalanine‒fructose complex (BPA–F) was studied with phantoms using1H magnetic resonance spectroscopy sequences PRESS and STEAM at 1.5 and 3.0 T. The results show that typical attainable short echo times of clinical MRS sequences combined with long repetition time result in clinically acceptable quantification accuracy. However, the concentration ratios, which are essential for the treatment planning, can still be reliably measured by using small repetition times. Detection limits of BPA in aqueous phantoms at 1.5 and 3.0 T were evaluated using clinically acceptable measurement time of ~10 min, two typical voxel sizes (153and 203mm3) and PRESS and STEAM sequences. The detection limits of BPA in phantom conditions were 0.7 (3.0 T) and 1.4 mM (1.5 T) for PRESS sequence with 203mm3voxel.

Boronated Compounds for Imaging Guided BNCT Applications

“…One of the problems confronting the successful clinical implementation of BNCT is the difficulty of quantitatively mapping the distribution of the boron containing molecules in patients during the treatment. [57][58][59] Furthermore, the clinical efficacy of the therapy is only guaranteed if the boron is located inside a tumor cell at a concentration of at least 20-30 ppm.…”

“…One of the problems is that the uptake and distribution of 10 B varies among patients and that large uncertainties exist in the tumor-to-blood 10 B concentration ratio. 57,58,84 At the same time the selective delivery of the NCT agent becomes one of the crucial points for the success of the treatment and only two compounds (BPA and BSH) have been extensively tested in both pre-clinical and clinical trials. Only proper NCT agent design, based on an improved knowledge of how molecules enter healthy and diseased cells, could allow the minimal intracellular concentration, needed to make NCT an effective therapy to cure cancer, to be reached.…”

“…57 Bendel and coworkers performed MRSI of BPA biodistribution in a mouse kidney (Figure 8 ) by introducing, along with the spatially selective pulses, a chemical shift selective pulse focused on the spectral region of the aromatic BPA protons. 58 Figure 8 BPA concentration map derived from dividing the BPA from the water intensity map superimposed on the FSE kidney image (images reprinted with the permission of the editor, license number 2762501109022).…”

Optimized 1H MRS and MRSI methods for the in vivo detection of boronophenylalanine

“…The possibility of detecting the aromatic BPA protons was recognized previously and demonstrated on a patient using standard STEAM (TE = 30 ms) (3). Subsequent studies characterized the echo‐time dependence of the aromatic proton BPA signals in aqueous solutions for STEAM and PRESS sequences (4, 5). As expected, these studies demonstrated the considerable modulation of the signal due to J ‐coupling, causing both phasing and signal loss problems and stressing the need for efficient, short‐TE sequences.…”