Imaging Mouse Prostate Gland by 3 Tesla Clinical MRI System

Abstract

In vivo detection of prostate tumor in animal model will facilitate the investigations that deal with the efficacy of different treatment strategies in different experimental settings. Recently higher field strength dedicated animal MRI system has been used successfully to detect mouse prostate glands and its lesions, however, usefulness of clinical system has not been utilized to its fullest extent. In this short communication we show the advantages and disadvantages of different in vivo imaging parameters of MRI to acquire images of the mouse prostate gland using clinical strength MRI systems.

Fig. 1

Schematic illustration of mouse urogenital systems adapted from “The Anatomy of the Laboratory Mouse by Margaret J. Cook, M.R.C. Laboratory Animals Centre, Carshalton, Surrey, England Academic Press, 1965” with permission. Copyright Elsevier.

Fig. 2. Identification of mouse prostate gland on MRI

The images were obtained by a 3 tesla MRI system using 50×108 mm Litzcage volume coil by Doty Scientific, using following imaging parameters: fast spin echo FATSAT T2-weighted sequence, TR/TE = 2000/13–15 ms, 25 to 30 mm FOV, 128×128 matrices, NEX = 3, slice thickness 0.7 to 0.9 mm. (A) axial, (B,C) sagittal, (D,E) coronal sections are showing prostate gland (white arrows). b = urinary bladder, t = testes. White arrows indicate the prostate gland. Arrow heads (B,E) indicate the preputial gland.

Fig. 3. Advantage of T2-weighted over T1-weighted images

(A) Axial T1-weighted image obtained using following parameters: TR/TE = 300/10 ms, 40×40 mm FOV, 128×128 matrices, NEX = 2. (B) Axial FSE fatsat T2-weighted image obtained using following parameters: TR/TE = 1800/13 ms, 25×25 mm FOV, 128×128 matrices, NEX = 4, slice thickness 0.7 mm. Note the clear demarcation of prostate gland on T2-weighted image (white arrows). b = urinary bladder.

Fig. 4. Advantages of FATSAT and longer TE for T2-weighted images

(A) Axial FSE T2-weighted image obtained using following parameters: TR/TE = 3850/12 ms, 30×30 mm FOV, 128×128 matrices, NEX = 3, slice thickness 1.2 mm. (B) FATSAT axial FSE T2-weighted image obtained at the same plane using following parameters: TR/TE = 3850/12 ms, 30×30 mm FOV, 128×128 matrices, NEX = 3, slice thickness 1.2 mm. Note the clear demarcation of the prostate gland on FATSAT T2-weighted image (white arrow). (C) FATSAT T2-weighted image obtained with short TE (20 ms) and (D) longer TE (40 ms) using similar parameters indicated above in A and B. b = urinary bladder, t = testes. Arrow heads (C,D) indicate preputial gland.

Fig. 5. Detection of implanted tumor in the left dorsolateral lobe of prostate by in vivo MRI

Tumors are shown in axial (A, B), coronal (C, D) and sagittal (E,F) planes. FATSAT T2-weighted images were obtained with short TE (12–13 ms, A, C and E) and long TE (69–73 ms, B, D and F). Note the better demarcation of tumor on images with long TE (arrows). b = urinary bladder, t = testes. White arrows indicate the tumor in prostate gland. Arrow heads (D) indicate preputial gland.

Fig. 6. Measurement of tumor and prostate gland

Tumor is outlined on axial, sagittal and coronal plans (A-D) indicating accurate demacation of tumor from normal prostate gland. Length of prostate gland including tumor (8 mm), length (6.5 mm) and width (5 mm) of the implanted tumor alone are shown (E), which are comparable to the tumor bearing extracted gland (F).