Clinical Feasibility Study of Prototype 1.5T & 3T Endorectal Coils

Prostate cancer is the most frequent non-cutaneous malignancy in the western
male population, with almost 200,000 newly diagnosed patients in the United
States in 2008 [1]. Due to widespread use of the prostate-specific antigen
(PSA) test and the lowered PSA threshold for biopsy, the number of newly
diagnosed Pca*s strongly increased [2]. Treatment selection depends on patient
age and general health, cancer stage and grade, morbidity and treatment
mortality, together with the preference of the patient and physician. Current
opinion is that localized prostate cancer can be treated successfully by
radical retropubic prostatectomy in the patient group with a life expectancy of
10 to 15 years or more.
Clinical assessment by digital rectal examination and measurement of
prostate specific antigen (PSA) level is not accurate in determining local
stage, with underestimations in as many as 40-60% of cases [3]. Accurate
staging with additional imaging methods is therefore an important issue for
correct management of prostate cancer patients. Among these imaging techniques,
transrectal ultrasound (TRUS) may enable correct assessment of locally advanced
tumors but is not sensitive enough to detect initial extraprostatic extension
across the capsule or into the seminal vesicles in clinically confined lesions
[4, 5].
Magnetic resonance (MR) imaging is considered to play an important role
in local staging of prostate cancer. Initially MR imaging was performed using a
conventional body coil with limited anatomical resolution. With the
introduction of new MR sequences, new coils and other technical developments
numerous studies have attempted to improve local staging. The diagnostic
capability of MR imaging in preoperative staging of prostate cancer is
currently being established.
The use of endorectal coils (eCoils) offers new possibilities in
prostate cancer imaging. Endorectal coils increase the signal-to-noise ratio
compared to pelvic phased array coils, which may lead to a higher spatial
resolution and subsequently better staging performance. The clinical available
endorectal coil is used over 15 years in our clinical practice (Radiology
Department of Radboud University Nijmegen Medical Centre). Recently, a new
prototype endorectal coil was developed with four receive channels compared to
1 receive channel in the current available endorectal coil. This new endorectal
coil allows for parallel imaging techniques which subsequently can lead to
decreased imaging time with similar image quality (compared to the clinical
available coil) or increased image quality with similar acquisition time.

To obtain data, images and feedback from the initial clinical use of
investigational four channel output eCoils designed for Siemens 1.5T and 3.0T
scanners compared to the current, commercially available single channel eCoils
for these field strengths and this MRI scanner.

This will be a prospective non-randomized single center study (RUNMC). A total
of 8 patients will be recruited and imaged with the current, commercially
available eCoil and the investigational four channel output eCoil at 1.5T and
3T (Four patients` will be imaged with the current commercially available eCoil
and the investigational eCoil at 1.5T and four patients will be imaged with the
current commercially available eCoil and the investigational eCoil at 3.0T.
Therefore each patient will have an additional endorectal MR examination (with
the prototype) direct after the diagnostic clinical endorectal MR examination.

MR imaging may cause some discomfort, such as feelings of claustrophobia and
discomfort due to loud sounds of the MR instrument during the study. Patients
are screened for prior claustrophobic symptoms using the same screening form
described above to search for metal device and foreign bodies. Earplugs are
provided to all patients in order to minimize the discomfort related to the
loud noise. The insertion of the endorectal coil may cause discomfort.
Lidocaine gel is inserted into the rectum for local anesthesia of the rectal
wall.