Reproducibility of 3D ¹H MR spectroscopic imaging of the prostate at 1.5T

Abstract

Purpose: To determine the reproducibility of 3D proton magnetic resonance spectroscopic imaging ( 1 H-MRSI) of the human prostate in a multicenter setting at 1.5T. Materials and Methods:Fourteen subjects were measured twice with 3D point-resolved spectroscopy (PRESS) 1 H-MRSI using an endorectal coil. MRSI voxels were selected in the peripheral zone and combined central gland at the same location in the prostate in both measurements. Voxels with approved spectral quality were included to calculate Bland-Altman parameters for reproducibility from the choline plus creatine to citrate ratio (CC/C). The repeated spectroscopic data were also evaluated with a standardized clinical scoring system.Results: A total of 74 voxels were included for reproducibility analysis. The complete range of biologically interesting CC/C ratios was covered. The overall within-voxel standard deviation (SD) of the CC/C ratio of the repeated measurements was 0.13. This value is equal to the between-subject SD of noncancer prostate tissue. In >90% of the voxels the standardized clinical score did not differ relevantly between the measurements. Conclusion: Repeated measurements of in vivo 3D1 H-MRSI of the complete prostate at 1.5T produce equal and quantitative results. The reproducibility of the technique is high enough to provide it as a reliable tool in assessing tumor presence in the prostate. REGARDLESS OF MANY IMPROVEMENTS in diagnosis and treatment of prostate cancer that were achieved in the last decades, it is still estimated to be the second leading cancer-related cause of death in American men in 2010 (1). Prostate cancer can be suspected with either a positive traditional digital rectal examination (DRE) and/or when high levels of prostate-specific antigen (PSA) are present in the blood. For conclusive evidence of tumor presence the histopathologic confirmation determined from a biopsy specimen is required.In order to improve the noninvasive detection of cancer in the prostate, its location, heterogeneous extent, grade, and stage, several techniques have been and are being explored. Among these proton magnetic resonance spectroscopic imaging ( 1 H-MRSI) in combination with conventional magnetic resonance imaging (MRI) has shown promising results in several single-site studies and in one multicenter study (2-6). However, another multicenter trial did not report a benefit of combined 1 H-MRSI and MRI in the localization of prostate tumors (7). Lack of reproducibility data, a more qualitative rather than quantitative spectroscopic evaluation, and the lack of multicenter validation of the used technique obscured the exact reason for this outcome.With 1 H-MRSI 3D metabolic information is obtained in vivo in addition to the morphological data of MRI

Mapping of prostate cancer by 1H MRSI

“…Further improvement in the acquisition of MRSI data of the prostate is ongoing, in particular to make the method more robust in dealing with movement and field inhomogeneities; however, the major MR manufacturers now provide acquisition protocols at 3 T that allow successful and reproducible 3D MRSI measurements of the prostate . As the current lack of appropriate and automated processing and display of the results strongly hampers clinical routine application, we paid particular attention to these aspects of prostate MRSI in this review.…”

Prebiopsy magnetic resonance spectroscopy and imaging in the diagnosis of prostate cancer

“…High specificity of 3D‐MRSI to identify cancer can be used to improve the ability of MRI to detect cancer within the prostate. MRSI of the prostate have high reproducibility to use this technique as a reliable tool in assessing tumor probability in the prostate 33 . Scheidler et al.…”

“…MRSI of the prostate have high reproducibility to use this technique as a reliable tool in assessing tumor probability in the prostate. 33 Scheidler et al obtained 91% specificity with the use of combined MRI/3D-MRSI for detection of cancer, whereas high sensitivity (95%) was obtained when either test provided a positive result. 34 The accuracy of MRI and MRSI for detection of prostate cancer is similar to that of a sextant biopsy, except in the prostate apex.…”

Role of high‐field MR in studies of localized prostate cancer

“…The ratio of signal integrals of choline + creatine to citrate combines these effects and is used as a marker for prostate cancer. This quantitative marker can be analyzed separately or in combination with the choline‐to‐creatine ratio in the standardized threshold approach , providing a reproducible measure to be used to predict tumor presence and absence in both the peripheral as well as the transition zone, and it can help in determining prostate cancer aggressiveness .…”