European Society of Uroradiology (ESUR), American College of Radiology (ACR), and AdMetech Foundation guidelines recommend the use of an antiperistaltic agent such as intramuscular (IM) glucagon to reduce motion artifact from bowel peristalsis for improved magnetic resonance imaging (MRI) detection of prostate cancer.^1,2 However, there are no studies that have examined whether the additional time, cost, patient discomfort, and drug reaction risk incurred by administration of IM glucagon results in improved image quality in the setting of increased widespread use of prostate MRI.

After an institutional protocol change to discontinue IM glucagon administration to patients undergoing prostate MRI studies, we retrospectively identified with IRB approval 25 cases of patients who received 1 mg glucagon IM shortly prior to scanning and 26 cases of patients who did not receive IM glucagon. A multiparametric MRI protocol was performed for all patients on a 3.0 Tesla scanner (GE MR750, Waukeshaw) without an endorectal coil.

Imaging parameters include: Small field-of-view (sFOV) T2: FSE, 416 x 224 matrix, 3.6-mm slices, 20-cm FOV, TE 130 ms, TR 4100 ms. Scan time: 2.04 min. Diffusion weighted imaging (DWI): reduced field of view EPI, 160 x 80 matrix, 4.2-mm slices, TR 2000 ms, 24 x 12-cm FOV, NEX 2 (B0) or 64 (B1200). Time to acquire a slice: B0 image 4 sec, B1200 image 2.1 min. Dynamic contrast-enhanced (DCE): Multiphase post-contrast 3D Dual Echo SPGR with the first venous phase (“peak”) used.

Two radiologists with 9 and 3 years of experience interpreting prostate MRI studies blinded to patient identity, study date, and administration of IM glucagon, independently scored all 51 cases for motion-related blurring of pelvic organs including the bowel, lymph nodes/iliac vessels, and prostate on sFOV T2, peak DCE, and B0 and B1200 DWI sequences using a five-point Likert scale (Tables 1, 2). The null hypothesis of no significant difference in scores was assessed using a Wilcoxon rank sum test with a target alpha of 0.05 for each reader. A kappa statistic was used to evaluate for inter-observer agreement.

As inter-reader agreement indicated by the kappa statistic demonstrated a wide range from slight to substantial, results were assessed independently for each reader. No significant difference in scores was identified in all categories for visualization of pelvic structures in all sequences for both readers (Table 3). Representative images are shown in Figures 1-2.While prior studies have shown that administration of IM butylscopolamine^3,4 for prostate MRI at 1.5T and 3T did not result in significantly improved image quality compared to studies performed without butylscopolamine, no published studies to our knowledge have objectively evaluated the effect of IM glucagon on image quality for prostate MRI studies. No significant effect of IM glucagon administration on MR image quality was observed, suggesting that IM glucagon is not mandatory for 3T prostate MRI.