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Background: Pancreatic ductal adenocarcinoma (PDA) is the third leading cause of cancer-related death in the United States. However, early response assessment using the current approach of measuring changes in tumor size on computed tomography (CT) or MRI is challenging., Purpose: To investigate the feasibility of hyperpolarized (HP) [1- 13 C]pyruvate MRI to quantify metabolism in the normal appearing pancreas and PDA, and to assess changes in PDA metabolism following systemic chemotherapy., Study Type: Prospective., Subjects: Six patients (65.0 ± 7.6 years, 2 females) with locally advanced or metastatic PDA enrolled prior to starting a new line of systemic chemotherapy., Field Strength/sequence: 3-T, T1-weighted gradient echo, metabolite-selective 13 C echoplanar imaging., Assessment: Time-resolved HP [1- 13 C]pyruvate data were acquired before (N = 6) and 4-weeks after (N = 3) treatment initiation. Pyruvate metabolism, as quantified by pharmacokinetic modeling and metabolite area-under-the-curve ratios, was assessed in manually segmented PDA and normal appearing pancreas ROIs (N = 5). The change in tumor metabolism before and 4-weeks after treatment initiation was assessed in primary PDA (N = 2) and liver metastases (N = 1), and was compared to objective tumor response defined by response evaluation criteria in solid tumors (RECIST) on subsequent CTs., Statistical Tests: Descriptive tests (mean ± standard deviation), model fit error for pharmacokinetic rate constants., Results: Primary PDA showed reduced alanine-to-lactate ratios when compared to normal pancreas, due to increased lactate-to-pyruvate or reduced alanine-to-pyruvate ratios. Of the three patients who received HP [1- 13 C]pyruvate MRI before and 4-weeks after treatment initiation, one patient had a primary tumor with early metabolic response (increase in alanine-to-lactate) and subsequent partial response according to RECIST, one patient had a primary tumor with relatively stable metabolism and subsequent stable disease by RECIST, and one patient had metastatic PDA with increase in lactate-to-pyruvate of the liver metastases and corresponding progressive disease according to RECIST., Data Conclusion: Altered pyruvate metabolism with increased lactate or reduced alanine was observed in the primary tumor. Early metabolic response assessed at 4-weeks after treatment initiation correlated with subsequent objective tumor response assessed using RECIST., Level of Evidence: 2 TECHNICAL EFFICACY: Stage 2., (© 2023 International Society for Magnetic Resonance in Medicine.)

Background: Hyperpolarized 13 C MRI quantitatively measures enzyme-catalyzed metabolism in cancer and metabolic diseases. Whole-abdomen imaging will permit dynamic metabolic imaging of several abdominal organs simultaneously in healthy and diseased subjects., Purpose: Image hyperpolarized [1- 13 C]pyruvate and products in the abdomens of healthy volunteers, overcoming challenges of motion, magnetic field variations, and spatial coverage. Compare hyperpolarized [1- 13 C]pyruvate metabolism across abdominal organs of healthy volunteers., Study Type: Prospective technical development., Subjects: A total of 13 healthy volunteers (8 male), 21-64 years (median 36)., Field Strength/sequence: A 3 T. Proton: T 1 -weighted spoiled gradient echo, T 2 -weighted single-shot fast spin echo, multiecho fat/water imaging. Carbon-13: echo-planar spectroscopic imaging, metabolite-specific echo-planar imaging., Assessment: Transmit magnetic field was measured. Variations in main magnetic field (ΔB 0 ) determined using multiecho proton acquisitions were compared to carbon-13 acquisitions. Changes in ΔB 0 were measured after localized shimming. Improvements in metabolite signal-to-noise ratio were calculated. Whole-organ regions of interests were drawn over the liver, spleen, pancreas, and kidneys by a single investigator. Metabolite signals, time-to-peak, decay times, and mean first-order rate constants for pyruvate-to-lactate (k PL ) and alanine (k PA ) conversion were measured in each organ., Statistical Tests: Linear regression, one-sample Kolmogorov-Smirnov tests, paired t-tests, one-way ANOVA, Tukey's multiple comparisons tests. P ≤ 0.05 considered statistically significant., Results: Proton ΔB 0 maps correlated with carbon-13 ΔB 0 maps (slope = 0.93, y-intercept = -2.88, R 2  = 0.73). Localized shimming resulted in mean frequency offset within ±25 Hz for all organs. Metabolite SNR significantly increased after denoising. Mean k PL and k PA were highest in liver, followed by pancreas, spleen, and kidneys (all comparisons with liver were significant)., Data Conclusion: Whole-abdomen coverage with hyperpolarized carbon-13 MRI was feasible despite technical challenges. Multiecho gradient echo 1 H acquisitions accurately predicted chemical shifts observed using carbon-13 spectroscopy. Carbon-13 acquisitions benefited from local shimming. Metabolite energetics in the abdomen compiled for healthy volunteers can be used to design larger clinical trials in patients with metabolic diseases., Evidence Level: 2 TECHNICAL EFFICACY: Stage 1., (© 2022 International Society for Magnetic Resonance in Medicine.)

Background: MR enterography (MRE) is generally performed without bowel preparation, but the frequency and extent by which bowel contents affect bowel wall visualization are poorly described in the literature., Purpose: To evaluate MRE bowel wall visualization quality relative to bowel lumen contents and patient demographics., Study Type: Retrospective, single-center., Population: One hundred and four consecutive patients (mean age 29 years, range 5-76 years) without prior bowel resection who had undergone MRE., Field Strength/sequence: 3 T (N = 87) or 1.5 T (N = 17)/T2-weighted single-shot spin echo (T2WI) and fat-saturated T1-weighted gradient echo (T1WI) without and with gadolinium., Assessment: For the proximal and distal jejunum and ileum and colon, three readers independently categorized bowel lumen signal (water = bright T2 dark T1, T1-bright, or air = dark T2 and T1 signal) and scored distension (0 = poor, 1 = moderate, 2 = well) and wall enhancement (0 = unclear, 1 = perceptible, 2 = clear) based upon gadolinium enhanced T1WI for the 104 MRE exams). The bowel visualization score was the sum of the wall enhancement and distension scores and was considered adequate if ≥3., Statistical Tests: Wilcoxon signed-rank test., Results: The bowel lumen content was water signal in 93% (97/104 scans), 92% (95/104), 98% (102/104), and 93% (92/104) of the proximal and distal jejunum and proximal and distal ileum, respectively, but only in 12.5% (13/104) of the colon. There was adequate bowel visualization of 53.8%, 77.8%, 84.6%, 90.4% of the proximal and distal jejunum and proximal and distal ileum, respectively, but only 19.2% of the colon. In children (age < 18 years), the visualization score of the ileum was lower when the adjacent colon contained air (2.4 ± 0.97) compared to water (3.75 ± 0.29, P < 0.05) or T1-bright material (3.21 ± 0.82, P < 0.05)., Data Conclusion: Without bowel preparation, colon wall visualization was often unsatisfactory at MRE, and air-filled colon also degraded small bowel visualization, particularly in children., Level of Evidence: 4 TECHNICAL EFFICACY: Stage 1., (© 2021 International Society for Magnetic Resonance in Medicine.)

Purpose: To compare the apparent diffusion coefficient (ADC) of hyperpolarized (HP) [ 13 C, 15 N]urea to the ADC of endogenous water in healthy and fibrotic mouse liver., Materials and Methods: ADC measurements for water and [ 13 C]urea were made in agarose phantoms at 14.1T. Next, the ADC of water and injected HP [ 13 C, 15 N]urea were measured in eight CD1 mouse livers before and after induction of liver fibrosis using CCl 4 . Liver fibrosis was quantified pathologically using the modified Brunt fibrosis score and compared to the measured ADC of water and urea., Results: In cell-free phantoms with 12.5% agarose, water ADC was nearly twice the ADC of urea (1.93 × 10 -3 mm 2 /s vs. 1.00 × 10 -3 mm 2 /s). The mean ADC values of water and [ 13 C, 15 N]urea in healthy mouse liver (±SD) were nearly identical [(0.75 ± 0.11) × 10 -3 mm 2 /s and (0.75 ± 0.22) × 10 -3 mm 2 /s, respectively]. Mean water and [ 13 C, 15 N]urea ADC values in fibrotic liver (±SD) were (0.84 ± 0.22) × 10 -3 mm 2 /s and (0.75 ± 0.15) × 10 -3 mm 2 /s, respectively. Neither water nor urea ADCs were statistically different in the fibrotic livers compared to baseline (P = 0.14 and P = 0.99, respectively). Water and urea ADCs were positively correlated at baseline (R 2  = 0.52 and P = 0.045) but not in fibrotic livers (R 2  = 0.23 and P = 0.23)., Conclusion: ADC of injected hyperpolarized urea in healthy liver reflects a smaller change as compared to free solution than ADC of water. This may reflect differences in cellular compartmentalization of the two compounds. No significant change in ADC of either water or urea were observed in relatively mild stages of liver fibrosis., Level of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:141-151., (© 2017 International Society for Magnetic Resonance in Medicine.)

Purpose: To implement and evaluate combined parallel magnetic resonance imaging (MRI) and partial Fourier acquisition and reconstruction for rapid hyperpolarized carbon-13 ((13) C) spectroscopic imaging. Short acquisition times mitigate hyperpolarized signal losses that occur due to T1 decay, metabolism, and radiofrequency (RF) saturation. Human applications additionally require rapid imaging to permit breath-holding and to minimize the effects of physiologic motion., Materials and Methods: Numerical simulations were employed to validate and characterize the reconstruction. In vivo MR spectroscopic images were obtained from a rat following injection of hyperpolarized (13) C pyruvate using an 8-channel array of carbon-tuned receive elements., Results: For small spectroscopic matrix sizes, combined parallel imaging and partial Fourier undersampling resulted primarily in decreased spatial resolution, with relatively less visible spatial aliasing. Parallel reconstruction qualitatively restored lost image detail, although some pixel spectra had persistent numerical error. With this technique, a 30 × 10 × 16 matrix of 4800 3D MR spectroscopy imaging voxels from a whole rat with isotropic 8 mm(3) resolution was acquired within 11 seconds., Conclusion: Parallel MRI and partial Fourier acquisitions can provide the shorter imaging times and wider spatial coverage that will be necessary as hyperpolarized (13) C techniques move toward human clinical applications., (Copyright © 2013 Wiley Periodicals, Inc., a Wiley company.)