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and was DCE-positive, with increased uptake and washout
of contrast agent, and MRSI-positive, with elevated choline
and reduced citrate on 1H MRSI. The overall Prostate
Imaging-Reporting and Data System v.2 score was 5.
A shows the HP 13C spectral array for the baseline
scan, with markedly elevated lactate peaks within tumor-
containing voxels. A color scale map of dynamic pyruvate-
to-lactate metabolic flux (kPL) values likewise shows
markedly elevated flux levels in the tumor compared to
adjacent normal tissue in the baseline HP [13C]-pyruvate
MRI.
At 6 wk after initiation of ADT, repeat imaging
demonstrated nearly complete abrogation of elevated HP
lactate peaks on HP 13C MRI B) and associated near
complete diminution of intratumoral kPL values on dynamic
imaging (k PL max 0.025 s 1 at baseline and 0.007 s 1 on
follow-up). Notably, there was negligible change in size of
tumor on T2-weighted MRI and only a modest change on
ADC imaging, supporting the ability of HP 13C MRI to detect
early metabolic responses before such a response can be
ascertained using standard radiographic criteria. Concor-
dant with these findings, the patient subsequently achieved
a marked clinical response, with an undetectable serum PSA
nadir at 6 mo after ADT initiation.
This first patient example illustrates the potential of HP
[13C]-pyruvate imaging as a metabolic biomarker of
response. Further clinical studies investigating the associa-
tion between metabolic changes on HP 13C MRI and
response and resistance to treatment are ongoing.
Conflicts of interest: The authors have nothing to disclose.
Acknowledgments: This work was supported by NIH [2_TD$DIFF]grants [3_TD$DIFF]
R01EB017449, [4_TD$DIFF]P41EB013598, [5_TD$DIFF]and [6_TD$DIFF]R01CA166655. [7_TD$DIFF]We [8_TD$DIFF]would [9_TD$DIFF]like [10_TD$DIFF]to [11_TD$DIFF]
acknowledge [12_TD$DIFF]the [13_TD$DIFF]following [14_TD$DIFF]for [15_TD$DIFF]their [16_TD$DIFF]contribution: [17_TD$DIFF]Robert[18_TD$DIFF]A. [19_TD$DIFF]Bok, [20_TD$DIFF]Peder [21_TD$DIFF]E.
Z. [22_TD$DIFF]Larson, [23_TD$DIFF]Jeremy [24_TD$DIFF]W. [25_TD$DIFF]Gordon, [26_TD$DIFF]Hsin-Yu [27_TD$DIFF]Chen, [28_TD$DIFF]Marcus Ferrone, [29_TD$DIFF]James B.
Slater, [21_TD$DIFF]Mark [30_TD$DIFF]van [31_TD$DIFF]Criekinge, [32_TD$DIFF]Lucas Carvajal, [33_TD$DIFF]Sarah J. Nelson, [21_TD$DIFF]Eric [34_TD$DIFF]J. [23_TD$DIFF]Small, [19_TD$DIFF]
Matt [35_TD$DIFF]Cooperberg, Pamela N. Munster, and Albert Chang.
References
[1]
[1_TD$DIFF]
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[2]
[3]
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[4]
University of California San Francisco, San Francisco, CA, USA
*Corresponding author. University of California San Francisco,
1600 Divisadero Street, San Francisco, CA 94131, USA.
Tel. +1 415 3539278; Fax: +1 415 3537779.
E-mail address: (R. Aggarwal).
July 19, 2017
[(Fig._1)TD$FIG]
Fig. 1 – Representative axial T2-weighted (T2W) anatomic image and corresponding water apparent diffusion coefficient (ADC) image and T2W image
with an overlaid pyruvate-to-lactate metabolic flux (kPL ) image and corresponding hyperpolarized (HP) 13C spectral array (SA) for a 52-yr-old prostate
cancer patient with extensive high-grade prostate cancer (A) before therapy and (B) 6 wk after initiation of androgen ablation and chemotherapy.
Before treatment, the region of prostate cancer can be clearly seen (red arrows) as a reduction in signal on the T2W and ADC images, and increased HP
lactate and associated kPL flux on HP 13 C MRI. After initiation of androgen deprivation therapy there was a significant reduction in reduction in HP
lactate and kPL to normal levels, with only a modest treatment effect on prostate volume and ADC.
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